progress report of /bericht des applications”...

Report 7/2002 – 6/2005 of the International Graduate School (InterGK) Neurosensory Science

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Progress Report of /Bericht des

International Graduate School („InterGK“) 591 “Neurosensory science, systems and applications”

Reporting Period: 7/2002 – 6/2005

1 General Facts/ Allgemeine Angaben..................................................................................3 1.1 General theme ........................................................................................................................ 3 1.2 Applicants .............................................................................................................................. 3 1.3 Changes in the group of applicants........................................................................................... 7 1.4 Reporting period ..................................................................................................................... 8 1.5 Number of Ph.D. students, postdocs and qualification students .................................................. 8

2 Research Programme / Forschungsprogramm ..............................................................8 2.1 Implementation and further development of the underlying research idea ................................... 8 2.2 Survey of promotions / Ph.D. students of the InterGK holding a scholarship ............................. 11 2.3 Survey of promotions / Ph.D. students of the Graduate School (not holding a scholarship) ......... 14 2.4 Post-docs of the Graduate School (holding a scholarship) ........................................................ 17 2.5 Post-docs of the Graduate School (not holding a scholarship) .................................................. 18 2.6 Qualifying stipendiat............................................................................................................. 18 2.7 Statement about the hints given in the granting letter............................................................... 19

3 Study program / Studienprogramm................................................................................. 20 3.1 Regular classwork................................................................................................................. 20 3.2 Compact lab courses ............................................................................................................. 25 3.3 Seminar of the graduate school.............................................................................................. 25 3.4 Regular exchange seminar Groningen-Oldenburg ................................................................... 30 3.5 Monthly meetings of all EuroGK-members (Groningen and Oldenburg) ................................... 31 3.6 Summer schools and symposia ............................................................................................... 36

3.6.1 Symposium 2002 “Binaural Hearing at Cocktail Parties,” HWK Delmenhorst, 12-14th August 2002 ........................................................................................................37

3.6.2 Symposium: Pitch: Neural Coding and Perception", August 14 - 18, 2002, Hanse-Wissenschaftskolleg Delmenhorst .............................................................................37

3.6.3 Symposium 2002 “The Cognitive Neuroscience of Individual Differences - New Perspectives” HWK Delmenhorst, 7.-9. Nov 2002....................................................38

3.6.4 Summerschool 2003, September 4th – 6th in Odoorn, NL: Parallels in visual and auditory processing : Adaptation and localization............................................................38

3.6.5 Summerschool 19.-22. 8. 2004: Object formation in audition and vision: Bottom-up and top-down processing............................................................................................40

3.6.6 Symposium 23.-24. August 2004: First Hanse Workshop of HEARing Research at the HWK: Auditory scene analysis and speech perception by human and machine"41

3.6.7 Symposium 11.-13.August 2005: 2nd Hanse Workshop of HEARing Research at the HWK “Sensory worlds: a comparative view on sensory perception” .......................42

3.7 Courses for „soft skills“......................................................................................................... 42 3.8 Qualifying phase for qualification stipends ............................................................................. 42 3.9 Transition from the previous to the current generation of Ph. D. students.................................. 43

4 Mentoring concept / Betreuungskonzept...................................................................... 43 4.1 Advertisement of positions .................................................................................................... 43 4.2 Selection procedure............................................................................................................... 43 4.3 Supervision .......................................................................................................................... 43 4.4 Network of Ph.D. students..................................................................................................... 44

5 Guest scientist program /Gastwissenschaftlerprogramm........................................ 44


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6 Organizational structure of the InterGK / Organisationsstruktur des Graduiertenkollegs .............................................................................................................. 46

7 Structural and organizational pre-requisites for the graduate school/ Umfeld des Graduiertenkollegs .............................................................................................................. 46

7.1 Sonderforschungsbereich 517 “Neurokognition” (Bremen/Oldenburg):.................................... 46 7.2 SFB/Transregio 31 “Das aktive Gehör”:................................................................................. 47 7.3 Kompetenzzentrum HörTech:................................................................................................ 47 7.4 Bachelor/Master program “Hörtechnik und Audiologie”:......................................................... 47 7.5 Laboratory facilities in Oldenburg.......................................................................................... 48 7.6 Laboratory facilities in Groningen.......................................................................................... 48 7.7 Additional support by the University of Oldenburg ................................................................. 49

8 Concluding remarks / Zwischenbilanz ........................................................................... 49

Appendix I: Short Reports of the Graduates

Appendix II: Short reports of the contributing research groups


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1 General Facts/ Allgemeine Angaben 1.1 General theme

Neurosensory science, systems and applications: Measuring and modelling the processing of sensory information and its applications

Neurosensorik: Erfassung, Modellierung und Anwendung der neuronalen Verarbeitung von Sinneseindrücken

1.2 Applicants

Prof. Dr. rer. nat. Dr. med. Birger Kollmeier (Chairman/Sprecher) Institut für Physik, Medizinische Physik, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Tel.: (+49)-441-798-5470 Fax: (+49) -441-798-3902, e-mail: [email protected] http://medi.uni-oldenburg.de Prof. dr. Hendrikus Duifhuis (Vice chairman/ stellv. Sprecher until 6/05) Biomedical Technology, Graduate School of Behavioural and Cognitive Neurosciences, Rijksuniversiteit Groningen, Nijenborgh 4, NL - 9747 AG Groningen Tel.: (+31)-50 363-4732/33, e-mail: [email protected] Prof. Dr. Pim van Dijk (Vice chairman/ stellv. Sprecher starting 7/05) Dept. Of Otorhinolaryngology, University Medical Centre Groningen P.O. Box 30.001, 9700 RB Groningen, The Netherlands Email: [email protected]


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Name Institution Address Telephone/Fax E-Mail/Internet-address Research area Prof. Dr. Dr. Birger Kollmeier (Chairman/Sprecher)

Fakultät V, Institut für Physik, Medizinische Physik

Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg

(+49)-441-798-5470 (+49)-441-798-3902

[email protected] http://medi.uni-oldenburg.de

Psychoacoustics, Speech processing, auditory neurophysiology, hearing technology

Prof. Dr. Hendrikus Duifhuis (Vice chairman/ stellv. Sprecher)

Biomedical Technology, Graduate School of Behavioural and Cognitive Neurosciences

Rijksuniversiteit Groningen, BCN Neuro Imaging Center, Antonius Deusinglaan 2, 9713 AW Groningen, The Netherlands

(+31)-50-363-4733 (+31)-50-363-4740

[email protected] http://www.rug.nl/bcn/index

Cochlear mechanics, Speech recognition, auditory fMRI Neurocognition of visual perception and auditory processing

Prof. Dr. Hans Colonius Fakultät IV, Institut für Psychologie, Kognitionsforschung


(+49)-441-798-5158 (+49)-441-798-5158

[email protected] http://www.psychologie. uni-oldenburg.de/ kognition/-index.html

Mathematical psychology, auditory-visual interaction, psychoacoustics

Prof. Dr. Ulrike Feudel Fakultät V, Institut für Chemie und Biologie des Meeres, Theorie komplexer Systeme


(+49)-441-798-2790 (+49)-441-798-3404

[email protected] http://www.icbm.de/komplsyst

theory of complex systems, nonlinear dynamics, theoretical physics in biology

Prof. Dr. Mark Greenlee Institut für Experimentelle Psychologie

Universität Regensburg, D-93050 Regensburg

(+49)-941-943-3281

[email protected] http://www.psychologie. uni-regensburg.de/ Greenlee/-index1.html

Neuropsychology, fMRI, Vision research oculomotor function

Prof. Dr. Ritske de Jong Dept. Of Experimental and Work Psychology, Exp. Psychology

Rijksuniversiteit Groningen, Faculty of Psychology, Grote Kruistraat 2/1, NL-9712 TS Groningen

(+31)-50-363-6463

[email protected] http://www.rug.nl/-gmw/faculteit/medewerkers/-objecten/459

Experimental and occupational psychology, Information Processing and Task Performance

Prof. Dr. Georg Klump Fakultät V, Institut für Biologie und Umweltwissenschaften, Zoophysiologie und Verhalten


(+49)-441-798-3400 (+49)-441-798-5615

[email protected] http://www.uni-oldenburg.de/-zoophysiologie/

Auditory physiology & psychophysics, neuroethology


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Jun.-Prof. Dr. Jutta Kretzberg

Fakultät V, Institut für Biologie und Umweltwissenschaften, Sinnesphysiologie


(+49)-441-798-3314

[email protected] http://www.uni-oldenburg.de/-sinnesphysiologie/

Sensory physiology, computational neuroscience

Prof. Dr. Nico Leenders Neurology, Graduate School of Behavioural and Cognitive Neurosciences

Department of Neurology, Groningen University Hospital, Hanzeplein 1, NL-9700 RB Groningen

(+31)-50-361-2433

[email protected] http://www.rug.nl/umcg/-faculteit/disciplinegroepen/-medischeFysiologie/-stamcelcluster/-neurologypetcenter

Motor Systems and Control

Prof. Dr. Volker Mellert Fakultät V, Institut für Physik, Akustik


(+49)-441-798-3569 (+49)-441-798-3698

mellert@aku. physik.uni-oldenburg.de http://www.physik.uni-oldenburg.de/aku/

Acoustics, psychoacoustics, hearing technology, psychophysics of vibration

Prof. Dr. Alfred Mertins Fakultät V, Institut für Physik, Signalverarbeitung


(+49)-441-798-3610 (+49)-441-798-3902

[email protected] http://www.uni-oldenburg.de/-sigproc/

Audio and Video Signal processing, communication theory

Prof. Dr. Wolfgang Nebel Fakultät II, Department for Computer Science, Eingebettete Hardware- /Software-Systeme


(+49)-441-9722-280 (+49)-441-9722-282

[email protected] http://ehs.informatik.uni-oldenburg.de/de/

Low-power VLSI-design, embedded systems

Prof. Dr. Nikolay Petkov Computer Science Rijksuniversiteit Groningen, Institute of Mathematics and Computing Science, P.O. Box 800, NL-9700 AV Groningen

Tel: (+31)-50-363 7129 (+31)-50-363-3800

[email protected] http://www.cs.rug.nl/~petkov/

Visual pattern recognition, Intelligent Systems

Prof. Dr. Doekele Stavenga

Neurobiophysics, Graduate School of Behavioural and Cognitive Neurosciences

Rijksuniversiteit Groningen, Neurobiophysica, Nijenborgh 4, NL-9747 AG Groningen

(+31)-50-363-4785 (+31)-50-363-4740

[email protected] http://neuro.phys.rug.nl/

Physiology and biophysics of visual and mechanosensory systems, Behavioural Neurosciences


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Jun.-Prof. Dr. Jesko Verhey

Fakultät V, Institut für Physik, Neurosensorik


(+49)-441-798-3451 (+49)-441-798-3902

[email protected] http://www.physik.uni-oldenburg.de/ medi/projects/-neuro/index.html

psychoacoustics, auditory neuroscience

Prof. Dr. Reto Weiler Fakultät V, Institut für Biologie und Umweltwissenschaften, Neurobiologie


(+49)-441-798-2581 (+49)-441-798-3423

[email protected] http://www.uni-oldenburg.de/-neurobiologie/

Neurobiology of the retina

Prof. Dr. Frans Zwarts Linguistics, Center for language and cognition, Graduate School of Behavioural and Cognitive Neurosciences

Rijksuniversiteit Groningen, University Bureau, Postbus 72, NL-9700 AB Groningen

(+31)-50-363-5857

[email protected] http://www.rug.nl/bcn/index

Auditory cognitive processes


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1.3 Changes in the group of applicants

- Prof. Dr. Mark Greenlee received a prestigious call for a C4-professorship in Regensburg and Konstanz in 2002 which he accepted in 2003. He continued to supervise some of the graduates who had already started the Ph.D.-program within the InterGK (Ignacio Vallines Garcia, Riklef Weerda, qualification stipendiat Prashant D’Souza). However, since the whole group moved to Regensburg in 2003/2004, the input of this group to the InterGK faded out with one exception: Stipendiat Dipl.-Psych. Riklef Weerda continues his Ph.D. project in Oldenburg and is now supervised by Prof. Colonius.

- Prof. Dr. Wolfgang Nebel has been elected to be the chair of the universities adjunct institute Offis at the beginning of 2005. Even though he supervised several dissertations in the InterGK so far (stipendiat Dr. Laila Kabous, associated Ph.D. student Arne Schulz, stipendiat Bodhisatya Sarker) he decided not to actively participate in the next granting period because he will not be able to spend as much time on the InterGK as he would want to.

- Prof. Dr. Alfred Mertins accepted the call for a professorship for speech processing and communication in 2003. Since then, he has built up a research group and is supervising one dissertation project (stipendiat Stefan Strahl) from the InterGK. He is supplementing the expertise of the applicants with his background in audio and video signal processing and communication engineering. Before entering Oldenburg University, he was an Associate Professor at the University of Wollongong/Australia.

- Prof. Dr. Andreas Hein was appointed as a professor in the computer science department of Oldenburg University in 2003. His expertise is in the area of medical robotics and automation and he will supplement the applicants’ expertise in the field of neurosensory applications/biomedical engineering. Prof. Hein was former senior research associate in a Fraunhofer Institute in Berlin in the research group headed by Prof. Lüth.

- Junior-Prof. Dr. Jesko Verhey joined the institute of physics in 2003 on a newly created junior-professorship ”Neurosensorik” granted to the institute of physics by the administration of C.v.O. University in order to strengthen the newly created “Forschungszentrum Neurosensorik/research center for neurosensory science”. Formerly, he was a post-doc at the Centre for the Neural Basis of Hearing (CNBH) in Cambridge/UK and will supplement the applicants´ expertise in the area of psychoacoustics and both psychological and physiological models of hearing. He is currently supervising the Ph.D. project of stipendiat Dipl. Phys. Stephan Heise.

- Junior-Prof. Jutta Kretzberg entered the institute of biology of Oldenburg University in 2004. Before this appointment she had a post-doc position at the Salk Institute in La Jolla/California, USA (working with Prof. Sejnowski). She will supplement the applicants expertise in the area of neural sensory models and experiments, especially in the tactile and the visual domain.

- PD Dr. Hendrik Mouritsen was awarded the leadership of a VW-foundation-funded “Nachwuchsgruppe” (start-up grant for establishing a research group) “animal navigation” in 2002. In the upcoming granting period, he will cover the sensory domains of vision and magneto perception and thus expand the sensory domains of the InterGK.

- At the Rijksuniversiteit Groningen, Prof. Zwarts was elected president of the RUG and thus could no longer actively participate in the InterGK. Beginning at September 1st, 2002, Prof. ter Horst succeded him as scientific director of the


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graduate school of behavioural and cognitive neuroscience (bcn) which partially overlaps with the InterGK. Profs. Leenders and de Jong shifted their respective research focus to a different area and hence did not participate in the InterGK program. Dr. Harold Bekkering left RUG in 2003

- Prof. Roerdink received a full professorship the computer science department in Groningen in 2003 and decided to actively participate in the InterGK and to take over the InterGK involvement from Prof. Petkov who has been elected to be the chair of computer science in Groningen. Prof. Roerdink brings in his special expertise in image processing and medical imaging.

- Likewise, Prof. P.van Dijk joined the audiological center at the KNO-department at RUG in 2004 and immediately joined the activities of the InterGK. He will bring in his expertise in audiology and auditory neuroscience into the InterGK and will be the vice-chairman in the new granting period.

1.4 Reporting period 1.7. 2002 – 30.6. 2005 1.5 Number of Ph.D. students, postdocs and qualification students Ph.D. students Post-Docs Qualification

stipendiates with stipend financed by DFG

24 (basic rate) 1 BAT IIa/2

5 (age-dependent basic rate)

1 (basic rate)

without DFG- stipend (OL)

9 3 -

without DFG-stipend (GRO)

14 1

2 Research Programme / Forschungsprogramm 2.1 Implementation and further development of the underlying research idea Even though generations of researchers will have to find out all details of neurosensory processes in humans and animals as well as the application of this knowledge to tasks performed by machines, a significant progress has been made in the InterGK during the reporting period in the three areas “measuring neurosensory processes”, “models of the neurosensory processes” and “applications”: In the experimental part of the InterGK, a broad variety of experimental methods was successfully applied to the three main sensory domains vision, audition and touch where details of the neurosensory process could be characterized. One highlight were the successful experiments conducted with the new 1.5 T fMRI machine in Oldenburg and the newly formed imaging center in Groningen where both visual and auditory research work is performed. The fMRI method was primarily used to study the visual representation in the brain during saccades and during psychophysical trials (dissertations Vallines and Weerda). For studying audiovisual and auditory effects in fMRI, noise reduction techniques and appropriate sparse stimulation patterns were developed (dissertations Reemken, Hoiting). In order to study the underlying neurosensory processes in more detail, optical and (multi-)electrode recordings from nerve cells were obtained to detail the mechanisms of light/dark adaptation in the retina (dissertations Shelley, Schütte, Greschner, post-doc project Pottek,) and to study auditory scene segretation mechanisms (post-doc project Bee). More integrative analysis of neural representations at several stages of the brain were achieved with EEG methods that were used to characterize the relation between the


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outer acoustical environment and its internal spatial representation (dissertation Junius). However, the InterGK did not only study objective correlates of neurosensory processes but also developed new psychophysical tasks that were either applied to vibration perception (dissertation Oey), to spatial auditory perception in mice (dissertation Maier) and to timbre perception in humans (dissertation Emiroglu). In order to better understand the relation between the different experimental findings and the general principles of neurosensory processing, the second focal point of the InterGK consisted in modelling projects, that were primarily limited to the auditory domain and audiovisual interaction. A variety of model structures (from the single neuron to simple neural networks up to “effective” models of information processing) were successfully developed and tested. The optimality of auditory filters and possible computationally efficient alternatives were investigated by the dissertation projects Strahl and post-doc project Zhou. On a more central processing level, binaural noise reduction (i.e. the human ability to suppress noise from undesired noise sources) was studied in the dissertation projects Beutelmann and Nitschmann. Another mechanism which also is important for noise suppression, but is primarily involved in forming auditory objects by cluste ring auditory channels with similar modulations (“comodulation masking release”) was both studied in humans (dissertation project Heise) in mice (dissertation project Klink) and modelled with an auditory-nerve-inspired model (dissertation projects Dicke and Buschermöhle). Finally, the audiovisual and tactile interaction was measured and modelled in the dissertation by Akerfelt. Based on both the experimental and the modelling inputs several application areas were considered that both provided a test for the underlying concepts and also helped to develop new research questions for experiments and modelling approaches. In the area of imaging, the development of experimental methods (especially for the difficult task of auditory fMRI) had a high priority (see above, dissertation Hoiting, Reemken, qualification phase stipendiat De Souza). Another important application area is the subjective assessment of annoyance exerted from acoustical noise (such as, e.g. tire-road noise, dissertation project Buss) and vibration (such as, e.g. seating vibration in cars and aircrafts, dissertation Bellmann). Finally, the application of neurosensory science to overcome sensory impairment is one of the focal points of the InterGK: While parts of the retina research form the prerequisites for appropriate retina implants (dissertations Greschner, Shelley), most research effort has been put on hearing impairment: Both psychological and physiological methods have been used to characterize hearing impairment more precisely (dissertation projects Fobel, Emiroglu). As a consequence, preprocessing algorithms for hearing instruments were developed that aim at scene decomposition and noise reduction based on particle filters (dissertation projects Nix and Meyer). Finally, the usage of sensory aids and its implication for language development were a subject of the dissertation by Steinbrink. Hence, several application fields have benefited from the neurosensory research and the close interaction between measurement, models and application research. Taken together, a variety of methods, neurosensory systems and research questions have been covered in the InterGK in the current granting period in a multidisciplinary approach. Even though this makes communication between the contributing scientists and PhD students difficult (i.e., a cell physiologist does not speak the same “language” as a communication engineer), both the researchers and the graduates developed a common language and profited considerably from the interactions among the disciplines and methods employed here. Obviously, a better understanding between the contributing


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research groups was achieved in the current granting period than in the initial phase of the Graduate School. Nevertheless, the initial research question (“How do our sensory systems transform physical stimuli into the corresponding neural representations and how can we employ this knowledge for selected applications?”) is far from being answered completely. Hence, the results of the current granting period form a good basis for the envisaged prolongation period of the InterGK.

The reports from the Ph.D. students, postdoctoral fellows and from the respective research group leaders are given in the appendix.


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2.2 Survey of promotions / Ph.D. students of the InterGK holding a scholarship

Name Title of Ph.D. thesis Supervisor (expected) date

of promotion Grade Granting period

Place and date of first qualification

Page number in report

Akerfelt, Annika Visual-Tactile Stop Signal Inhibition

Colonius 7/2004 magna cum laude 01.09.00 – 31.08.03 GB, York 7/2000 3

Beutelmann, Rainer

Modelling binaural speech intelligibility in rooms for normal-hearing and hearing-impaired listeners

Kollmeier 2006 01.11.03 – 31.07.05 D, Oldenburg 9/2003 9

Buschermöhle, Michael

Neurosensory Modelling of Signal detection in comodulated stimuli

Feudel 5/2007 16.06.04 – 31.05.06 D, Göttingen 7/2003 16

Dicke, Ulrike Neural models of modulation frequency analysis

Kollmeier 12/2003 magna cum laude 01.06.00 – 31.05.03 D, Bremen 1997 24

Emiroglu, Suzan

Auditory object recognition in normal and hearing-impaired listeners - Psychoacoustic measurements and modeling

Kollmeier 9/2006 01.09.03 – 30.09.03 D, München 3/2003 28

Fobel, Sandra

Relation between sensorineural hearing impairment and steady-state amplitude modulation following responses

Kollmeier - 01.07.00 – 14.02.03 16.07.03 – 15.11.03 D, Oldenburg 6/2000 38


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Heise, Stephan

Spectral and temporal effects in modulation perception

Verhey 01.03.05 – 31.05.06 D, Köln 2/2005 47

Junius, Dirk

Temporal and spatial aspects of hearing as revealed by auditory evoked potentials

Kollmeier 7/2005 magna cum laude 01.06.00 – 31.05.03 D, Oldenburg 5/2000 49

Krajsek, Kai - Feudel - 01.08.03 – 15.12.03 D, Bonn 3/2003 57

Maier, Julia Mechanisms of sound localization in the gerbil

Klump 5/2007 01.06.04 – 31.05.06 D, München 4/2004 60

Meyer, Ronny - Kollmeier 16.09.04 – 31.12.04 D, Oldenburg 9/2004 63

Nitschmann, Marc

Modeling inattention and across-frequency processing in binaural signal processing

Kollmeier 16.01.04 – 15.01.06 D, Kiel 1/2004 64

Nix, Johannes

Localization and Separation of Concurrent Talkers based on Principles of Auditory Scene Analysis and Multi-Dimensional statistical Methods

Kollmeier 07.07.2005 magna cum laude 01.01.02 – 15.08.02 D, Oldenburg 3/1999 66

Oey, Handy

Development of a model of vibration perception based on psychophysics and physiology of the somatosensory system

Mellert 11/2005 16.10.01 – 15.10.04 D, Oldenburg 10/2001 69

Sarker, Bodhisatya Low power design techniques

Nebel - 01.07.02 – 30.09.03 IIT Bombay, M.S, 2000

72


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Schütte, Frank

Nachweis und Charakterisierung Retinsäure-bindender Proteine in der Fischretina

Weiler 14.02.2005 magna cum laude 01.04.01 – 31.03.04 D, Oldenburg 1995 78

Shelley, Jennifer

Spatial properties of horizontal cell responses in the mouse retina

Weiler 3/2006 01.03.03 – 28.02.06 D, Tübingen 11/2002 82

Steenken, Rike t. b. a. Colonius 3/2008 01.03.05 – 31.05.06 D, Oldenburg 1/2005 86

Steinbrink, Claudia

Phonologische und flexionsmorphologische Fehler in der Sprache normal Hörender und hörgeschädigter Kinder

Colonius/Szagun 5/2004 magna cum laude 01.12.03 – 31.12.03 D, Oldenburg 11/1998 89

Strahl, Stefan Efficient coding of natural sounds

Mertins 10/2006 16.08.03 – 15.08.05 GB, London 9/2000 92

Vallines Garcia, José I.

Modulation of neural activity in Human visual cortex during saccade programming

Greenlee 11/2005 01.10.01 – 31.01.04 E, Madrid 6/2001 96

Weerda, Riklef

The human primary visual cortex and its role in visual awareness and visual search

Greenlee, Colonius 6/2006 01.01.05 – 31.05.06 D, Oldenburg 9/2002 99

Zhou, Huan

H2 and H8 Optimal Design of Multirate Filter Bank Systems

Mertins 5/2004 01.02.04 - 31.05.04 China 7/1994 107

Zokoll, Melanie Auditory memory in songbirds and humans

Klump 12/2006 08.04.03 – 07.04.06 D, München 4/2003 109


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2.3 Survey of promotions / Ph.D. students of the Graduate School (not holding a scholarship)

Name Title of Ph.D. thesis

Supervisor (expected) date of promotion

Grade Granting period Place and date of first qualification


Ballan, Meltem

Wavelet based methods for the analysis of fMRI time series

Roerdink 12/2008 01.11.2004 – 31.10.2008 5

van den Berg, Ronald

Visualisation Roerdink, Cornelissen

6/2008 01.06.2004 – 31.05.2008 NL, Groningen 2003 7

Boucard, Joyce Cortical consequences of visual field defects

Cornelissen, Roerdink 4/2006

01.01.2002 – 30.04.2006 E, Barcelona 13

Buss, Sandra

Zeitliche und spektrale Analyse akustischer Signale durch Konturierung

Mellert 12/2005 - D, Oldenburg 7/1999 19

ten Caat, Michael

Interactive Visualization Techniques for the Interpretation of Functional Neuroimaging Data

Roerdink 8/2007 01.09.2003 – 31.08.2007 22

Dinklo, Theo

Mechano- and electrophysiological studies on cochlear hair cells and superficial lateral line cupulae

van Netten, Stavenga

1/2005 01.07.1998 – 31.12.2002 NL, Nijmegen 8/1997 26

van Es, Just Natural Colour Constancy

Cornelissen, Roerdink

7/2007 01.08.2003 – 31.07.2007 NL, Groningen 6/2003 31

Ewert, Stephan

Frequency selectivity in auditory processing of amplitude modulation

Kollmeier 12/2002 magna cum laude - D, Oldenburg 5/1999 34


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Greschner, Martin

Die Zeitstruktur retinaler Ganglienzellantwor-ten unter dem Einfluss natürlicher Stimuli, insbesondere von Augenbewegungen

Weiler 10/2005 - D, Oldenburg 12/2000 41

Hannus, Aave Visual Channels in Action

Cornelissen, Bekkering

12/2005 01.01.2002 – 31.12.2005 Tartu 6/2001 44

Kleinschmidt, Michael

Robust Speech Recognition based on Spectro-temporal Processing

Kollmeier 5/2002 Magna cum laude - D, Oldenburg 3/1999 52

Klink, Karin B.

The role of inhibition in auditory processing of the mouse

Klump 12/05 - D, Bielefeld 2/2002 54

Lanting, Chris Auditory fMRI van Dijk 2009 01.06.2005 – 31.05.2009 NL, Groningen 58

Rizzo, Carlos Spatial Distribution of the fMRI transfer function

Duifhuis 2/2008 01.03.2004-01.02.2008 71

Schoffelen, Rick

The mechanical response of the tectorial membrane in the inner ear of the frog

van Dijk 2009 01.01.2005 – 31.12.2008 NL, Eindhoven 73

Schubert, Timm

Characterization of coupled networks and calcium currents in the vertebrate retina

Weiler 05/05 magna cum laude - D, Oldenburg 9/1999 75

Schulz, Arne

Classification scheme for IP -componenents to enable power modelling

Nebel 2006 - D, Oldenburg 4/2000 80


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Segger-Junius, Mailin

Characterization of the dendritic localization of the shank1-mRNA

Weiler 6/2003 magna cum laude - D, Oldenburg 5/2000 81

Slabu, Lavina M. Imaging Subcortical Auditory Activity in Humans using fMRI

Duifhuis 10/2007 15.10.2003-15.10.2007 85

Tomaskovic, Sonja

Audio-visual Integration in Speech Perception: An fMRI Study using the McGurk Effect

Duifhuis 11/2005 01.10.2001-01.11.2005 95

Wink, Alle Meije


Roerdink 3/2004 01.01.2000 . 31.12.2003 NL, Groningen 1999 105


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2.4 Post-docs of the Graduate School (holding a scholarship)

Name Project / Subject Special functions in and for the Graduate

School Publications Granting period

Place and date of promotion


Akerfelt, Annika - Speaker of the Ph.D. students SS2003

see report 01.08.04 – 30.09.04 D, Oldenburg 7/2004 112

Bee, Mark Allen

Neural Mechanisms of Auditory Scene Analysis in the European Starling (Sturnus vulgaris)

Native American speaker/ proofreader for publications

see report 01.03.03 – 30.11.03 01.10.04 – 31.03.05

Columbia, Missouri, USA 5/2001 120

Hoiting, Gerke Active Noise Reduction for auditory fMRI

Transfer of knowledge from Groningen to Oldenburg

- 01.02.05 – 30.09.05 NL, Groningen 1/2005 123

Pottek, Mark

Retinoic acid as a retinal modulator, Hemichannels: a novel role for gap junctions in the retina Light-evoked activity of single neurons in the mouse retina

Organized contacts and transfer between visual and auditory domain

see report 01.08.00 – 31.07.02 D, Oldenburg 7/2000 127

Zhou, Huan Scalable audio coding scheme development

Contact person for asian students

see report 01.06.04 – 31.01.05 Singapur 5/2004 130


18

2.5 Post-docs of the Graduate School (not holding a scholarship)

Name Project / Subject Special functions in

and for the Graduate School

Publications Place and date of

promotion Page number in

report

Anemüller, Jörn

Across-frequency processing in convolutive blind source separation

see report D, Oldenburg 7/2001 113

Arndt, Petra

Bewegungs- und Aufmerksamkeitssteuerung bei multimodaler Stimulation

- see report D, Bochum 1993 115

Mauermann, Manfred

Fine Structure in Distortion Product Otoacoustic Emissions and Auditory Perception

see report D, Oldenburg 2/2004 124

2.6 Qualifying stipendiat

Name Supervisor first qualification Place and date of first qualification

Granting period Age upon entry into the Graduate School


DeSouza, Prashanth Greenlee M. Eng. D, Emden + Oldenburg 11/2001

01.06.03 – 31.05.04 27 131


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2.7 Statement about the hints given in the granting letter

According to the reviewers’ comments transmitted by the DFG in the granting letter, the following actions have been taken:

- The project “Role of inhibition for cortical auditory pattern processing” was not pursued as a PhD project in the current granting period (as requested by the reviewers).

- The excellent co-operation between the research groups Greenlee and Cornelissen could unfortunately only partly be pursued due to the move of Prof. Greenlee to Regensburg in 2003. However, the practical co-operation between Groningen and Oldenburg could be strengthened in the following areas:

o auditory fMRI: The considerable experience of the Groningen group (Duifhuis) in performing auditory fMRI experiments was very useful in building up the experiments in Oldenburg (Uppenkamp/Kollmeier group). This was further pursued by a post-doc project from Gerke Hoiting who did his PhD work in Groningen and continued his post-doc in Oldenburg.

o Prof. Pim van Dijk has been elected as professor of audiology in Groningen in 2004 and has very similar research interests as the audiological group in Oldenburg (B. Kollmeier, J. Verhey, Mauermann). Since collaborations already existed with Prof. van Dijk’s previous affiliation in Maastricht, it is expected that several projects will be performed in collaboration in the future. Therefore, Prof. van Dijk agreed to take over the vice chairmanship of the InterGK.

o Two new groups working on image processing have been added to the InterGk: Prof. Roerdink (computer science) in Groningen as well as Prof. Mertins (physics) in Oldenburg. It is expected that these more theoretically oriented groups that use similar methods will form an additional communication axis within the InterGK in the upcoming granting period.

- Several measures have been taken to promote the graduates’ abilities in scientific discourse:

o The seminar of the InterGK was always conducted in English with special discussion groups before or after the seminar (see guest researcher programme).

o A large number of summer schools and international conferences were organized in the previous granting period that promoted the work of the graduate students by giving them the chance to present their work with international renowned scientists and to discuss their respective projects with them.

o The graduates were encouraged to visit foreign labs and to visit international conferences. However, a high priority was given to keeping the duration of the overall dissertation project within the given limits, so that a prolonged stay at a laboratory abroad could not be achieved by all graduates.

- The organization structure of the InterGK was made more transparent and the self-initiative of the graduate students was more reinforced by introducing the position of a speaker of the graduates who participated in the board meetings (see organization structure). Nearly all suggestions provided by the graduates could be implemented.with respect to invited speakers for the InterGK, special courses and meetings, excursions and other topics.


20

- Dissertation format: The University of Oldenburg has created the possibility to have joint dissertation together with the University of Groningen and to submit the dissertation in English for all faculties during the renewal of the organizational structures of the University in 2003.

Additional support from the University and the State of Lower Saxony: According to the recommendations given by the reviewers, the State of Lower Saxony has granted a total amount of 100,000 Euro and the University of Oldenburg has granted an additional amount of 16,000 Euro to finance additional devices for the contributing working groups required for performing the research of the graduates. In addition, the positions of a lab assistant (part-time) and an administrative assistant (quarter-time) were granted by the University of Oldenburg to the InterGK. Also, the InterGK was given highest priority to take advantage out of the stipends from the “Graduiertenförderungsgesetz” of the State of Lower Saxony (one additional stipend granted to S. Emiroglu).

3 Study program / Studienprogramm The study program for each Ph.D. student was assembled individually for each student according to his/her previous course work, special interest, and requirements for the respective dissertation project. Typically, each Ph.D. student performed the following study program: 3.1 Regular classwork Regular classes from the main curriculum of the respective universities (i. e., selection of course work that was “missing” in the previous education history and/or that have to be studied in order to understand and perform better in the respective research project). A list of courses that have regularly been selected by the students is given below Courses from the regular curriculum suitable for InterGK-Studens, Summerterm 2002 „Synaptische Integration in den plexiformen Schichten der Retina“ Reto Weiler „Präattentive Mechanismen der neuronalen Objektsegmentierung im visuellen und auditorischen System“

Leo van Hemmen

„Zusammenhang zwischen psychoakustischen Modellgrößen und akustisch erzeugten evozierten Potentialen“

Torsten Dau

„Auditorische räumliche Abbildung und Mechanismen der Objektbildung beim Menschen“

Birger Kollmeier

„Funktionelle kernspintomographische Untersuchungen des visuellen Arbeitsgedächtnisses“

Mark Greenlee

„Auditorische Wahrnehmungsprozesse bei Mausmutanten mit veränderten inhibitorischen Mechanismen“

Georg Klump

Courses from the regular curriculum suitable for InterGK-Studens, Winterterm 2002/2003 Neurokognition Montag 10 – 12, W4 1-172

Lehrende des SFB 517

Physiologie der Tiere und des Menschen I (VL) Sinnesphysiologie, Neurophysiologie, Muskelphysiologie Montag 10 – 12, W4 1-162

Feigenspan/Weiler

Physikalische Prinzipien beim Hören, neuronale Kodierung und Modellbildung (SE, VL) Dienstag 16 – 18

Dau

Physik für Studierende der Biologie (VL) Montag 14 – 16

Dau


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Psychoakustik (VL) Weber Medizinische Physik (SE) Dienstag 10 – 12, W2 1-143

Kollmeier

Einführung in die Kognitiven Neurowissenschaften (VL) Dienstag 14 – 16, A6 2-212

Greenlee

Kognitive Neuropsychologie (SE) Mittwoch 16 – 18, A6 2-223

Greenlee

Neuropraktikum (UE) Dienstag 16 – 18, A6 2-212

Greenlee

Vertiefungspraktikum Neuro- und Verhaltensphysiologie 2. Triade

Langemann/ Klump

Seminar zum Praktikum Neuro- und Verhaltensphysiologie 2. Triade

Langemann/ Klump

Sinnesphysiologische Experimente im Selbstversuch (SE) Mittwoch, 15 – 17

Langemann/ Klump

Physiologie des Hörsystems Mittwoch 13 – 15

Klump

Courses from the regular curriculum suitable for InterGK-Studens, Summerterm 2003 Neurokognition (SE) Freitag 10-12, W4 1-172


Sinnesphysiologie (VL) Donnerstag 12-13, W4 1-162

Weiler

Konfokale und elektronenmikroskopische Neuroanatomie (PR) Block 2 Wochen, ganztägig, n. V. - Vorbesprechung s. Aushang

Weiler/ Schultz

Ionenkanäle (VL) Dienstag 15-16, W4 1-172

Feigenspan

Neurobiologisches Seminar (SE) Donnerstag 17-19, W4 1-162

Klump/ Richter-Landsberg/ Weiler

Physikalische Prinzipien beim Hören, neuronale Kodierung und Modellbildung (SE) Dienstags 16-18, W2 1-128

Dau

Medizinische Physik (SE, A) (ECTS: 2) Dienstag 10-12, W2 1-143

Kollmeier

Fortgeschrittenenpraktikum (Blockpraktikum) „Psychophysik, Neurosensorik, und auditorische Signalverarbeitung“ (PR, E) September 2003, 2 Wochen, ganztägig, Termin der verbindlichen Vorbesprechung: wird per Aushang bekanntgegeben.

Verhey/Kollmeier u.a.

Physikalische Aspekte der Neurokognition (SE, A) (ECTS: 2) Dienstag 16-18, W2 1-128

Hohmann/Verhey

Neurokognition (SE, A) (ECTS: 2) Dienstag 16-18, W2 1-128

Hohmann/Verhey

Bildgebende Verfahren (VL, A) (ECTS: 2) Mittwoch 8-10, W2 1-143

Hohmann/Uppenkamp

Einführung in die klinische Neuropsychologie (VL) Dienstag 14-16, A6 2-212

Greenlee

Interdisziplinäre Perspektiven auf das visuelle System (SE, POK) Mittwoch 18-20, A6 2-223

Knauff/Möckel/ Rehkämper/ Ammermüller/ Greenlee/Sukale

Klinische Neuropsychologie (SE) Mittwoch 16-18, A6 2-223

Greenlee/Özyurt

Methoden der funktionellen Bildgebung (SE) Dienstag 16-18, A6 2-223

Rutschmann

Kernspintomographie (Blockpraktikum) (PR) Termin nach Vereinbarung. Vorläufiger Termin. Besprechung im Seminar

Rutschmann

Mechanismen des Verhaltens (VL) Mittwoch 13-15, W4 1-162

Klump


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Informationsverarbeitung und Verhalten (Blockseminar) (SE) 5.5.-6.5.03, W4 0-098

Friedl/Klump/ Langemann

Übungen zur statistischen Analyse in Neurobiologie und Verhalten (Blockveranstaltung) (VL/SE) 1.4.-4.4.03, W4 1-162


Informationsverarbeitung und Verhalten (PR) 7.5.-20.5.03, ganztätgig, W4 0-107 Vorbesprechung: 7.4.03, 12-13, W4 0-098


Courses from the regular curriculum suitable for InterGK-Studens, Winterterm 2003/2004 Physiologie der Tiere und des Menschen I VL Sinnesphysiologie, Neurophysiologie, Muskelphysiologie Montag 10-12, W04 1-162

Weiler

Physiologie der Tiere und des Menschen II VL Hormonphysiologie, Kreislaufphysiologie, Atmungsphysiologie, Stoffwechselphysiologie Mittwoch 12-14, W04 1-162

Weiler

Neuroanatomie PR, SE PR: ganztägig, 05.-30.01.2004, W4 1-194 [18], SE: Montag und Freitag, 16-18, 2. Semesterhälfte, s. Aushang

Janssen-Bienhold / Weiler

Konfokale und elektronenmikroskopische Neuroanatomie PR 2 Wochen, ganztägig [6]

Weiler / Schultz

Neurobiologie SE Freitag 12-14, W04 1-171

Janssen-Bienhold / Ammermüllerr / Feigenspan / Weiler

Neurokognition SE Vortragskolloquium des Sonderforschungsbereiches Freitag 10-12, W04 1-172

SFB-Projektleiter

Neurobiologisches Seminar SE Donnerstag 17-19, W04 1-172

Weiler / Richter-Landsberg / Klump

Physiologie des Hörsystems VL Mittwoch 12-14, W04 0-098

Klump

Grundlagen akustischer Wahrnehmungsprozesse SE Dienstag 16-18, W04 0-098

Langemann / Klump

Neuro- und Verhaltensphysiologie SE, PR 2 Wochen in der Zeit vom 24.11.-19.12.2003

Langemann / Klump

Einführung in die Medizinische Physik VL Freitag 8-10, W02 1-156

Kollmeier

Medizinische Physik SE, A Dienstag 10-12, W02 1-143

Kollmeier

Signal- und Sprachverarbeitung VL Montag 14-16, W02 1-156

Kollmeier, Mertins

Physikalische Prinzipien beim Hören, neuronale Kodierung und Modellbildung SE Dienstag 16-18, W02 1-128

Hohmann

Aktuelle Aspekte der Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung SE Donnerstag 8-10, A01 0-008

Arndt / Özyurt

Kognitive Neuropsychologie SE Ergänzungsseminar zur Vorlesung "Einführung in die kognitiven Neurowissenschaften" Mittwoch 16-18, A06 2-223

Arndt / Rutschmann / Weerda

Einführung in die kognitiven Neurowissenschaften VL Dienstag 14-16, A06 2-212

Arndt / Özyurt / Rutschmann


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Courses from the regular curriculum suitable for InterGK-Studens, Summerterm 2004 Diagnostik und Therapie zerebraler Sehstörungen (Agnosien, Dyslexien) Do 18 - 20, A06 1-112

Hildebrandt, Helmut

Neurodidaktik S Do 14 - 16, A07 0-031

Arndt, Petra

Sensomotorische Integration S Do 8 - 10, A06 2-223

Arndt, Petra

Modellierung S Do 10 - 12, A06 2-223

Colonius, Hans

Klinische Neuroanatomie S Di 14 - 16, A07 0-031

Möckel, Wolfgang

Kognitionspsychologie II V Di 16 - 18, A07 0-025

Zaus, Michael

Tutorium "Allgemeine Psychologie I" S Do 18 – 20

Zaus, Michael

Sinnesphysiologie V Mo 14 - 15, W04 1-162

Weiler, Reto

Ionenkanäle V Di 15 - 16, W04 1-172

Feigenspan, Andreas

Neurokognition S Fr 10 - 12, W04 1-172


Übungen zur statistischen Analyse in Neurobiologie und Verhalten V, S Blockveranstaltung 30.03.04 - 02.04.04, 10 - 13, W04 1-162

Friedl, Thomas / Klump, Georg / Langemann, Ulrike

Neurobiologisches Seminar S Do 17 - 19, W04 1-162

Klump, Georg / Richter-Landsberg, Christiane / Weiler, Reto

Konfokale und elektronenmikroskopische Neuroanatomie PR Block, 2 Wochen, ganztägig

Weiler, Reto / Schultz, Konrad

Medizinische Physik POP Do 16 - 19, Haus des Hörens

Brand, Thomas

Fortgeschrittenenpraktikum Versuche 13 – 16 PR (Blockpraktikum) Psychophysik (E). Neurosensorik und auditorische Signalverarbeitung. Ganztägig. zweiwöchig im September 2004

Verhey, Jesko / Kollmeier, Birger / N. N.

Physikalische, technische und medizinische Akustik VL, A Di 8 - 10, W02 1-156, 14-täglich (u) Fr 8 - 10, W02 1-128

Kollmeier, Birger

Medizinische Physik SE, A Di 10 - 12, W02 1-143

Kollmeier, Birger

Neurokognition SE, E, A Mi 12 - 14, W02 1-125

Hohmann, Volker / Verhey, Jesko

Bildgebende Verfahren VL, E Mi 8 - 10, W02 1-143

Hohmann, Volker / Uppenkamp, Stefan

Courses from the regular curriculum suitable for InterGK-Studens, Winterterm 2004/2005 Anleitung zum wissenschaftlichen Arbeiten DiplomandInnen-Kolloquium KO 2 SWS Di 10 - 12, A06 2-223

Arndt

Aktuelle Aspekte der Aufmerksamkeitsdefizit-/ Hyperaktivitätsstörung (6 KP) [SG] S Do 10 - 12, A04 2-221

Arndt / Behlmer-Elster,/ Özyurt

Experimentelle Ansätze der Bewusstseinsforschung (4 KP) S 2 SWS Do 10 - 12, A06 2-223

Colonius

Physiologie der Tiere und des Menschen I Sinnesphysiologie, Neurophysiologie, Muskelphysiologie [SG] V Mo 10 - 12, W04 1-162

Weiler


24

Physiologie der Tiere und des Menschen II Hormonphysiologie, Kreislaufphysiologie, Atmungsphysiologie, Stoffwechselphysiologie V Mi 12 - 14, W04 1-162

Weiler

Physiologie des Hörsystems V Di 12 - 14, W04 0-098 Di 12 - 13, W04 1-162

Klump

Grundlagen akustischer Wahrnehmungsprozesse S Di 15 - 17, W04 0-098

Langemann / Klump

Neurobiologisches Seminar S Do 17 - 19, W04 1-172

Weiler / Richter-Landsberg / Klump

Neuroanatomie ganztägig [18]: PR Blockveranstaltung 10.01.05 - 04.02.05, W04 1-194 2. Semesterhälfte, s. Aushang: S Mo 16 - 18, Fr 16 - 18

Janssen-Bienhold / Weiler

Neuro- und Verhaltensphysiologie 2 Wochen in der Zeit vom 18.10.-12.11.2004 [9] S , PR n. V.

Langemann / Klump

Konfokale und elektronenmikroskopische Neuroanatomie 2 Wochen, ganztägig [6] PR n. V.

Weiler / Schultz

Neurobiologie S Fr 12 - 14, W04 1-171

Janssen-Bienhold / Ammermüller / Feigenspan / Weiler

Psychologische, physiologische und audiologische Akustik (8 KP) V , S , Ü Mo 14 - 16, W02 1-156 Di 16 - 18, W02 1-156 Fr 8 - 10, W02 1-156

Hohmann / Kollmeier / Verhey

Medizinische Physik (2 KP) Di 10 - 12, W02 1-143

Kollmeier

Wavelets und Zeit-Frequenz-Analyse: Theorie und Anwendungen (6 KP) V , Ü Mi 14 - 16, W01 1-118 Mi 10 - 12, W02 1-148

Mertins

Courses from the regular curriculum suitable for InterGK-Studens, Summerterm 2005 Mechanismen des Verhaltens V Do 14 - 16, W04 1-162

Klump / Bee

Ionenkanäle V Di 15 - 16, W04 1-172

Feigenspan

Blockseminar Informationsverarbeitung und Verhalten S n. V. W04 0-098

Friedl / Klump / Langemann

Übungen zur statistischen Analyse in Neurobiologie und Verhalten Ü, S ganztägig, Beginn jeweils: 9:00 c.t. Blockveranstaltung 29.03.05 - 01.04.05, W02 2-224


Konfokale und elektronenmikroskopische Neuroanatomie PR Block, 2 Wochen, ganztägig, Vorbesprechung s. Aushang

Weiler / Schultz

Informationsverarbeitung und Verhalten PR Voraussetzung ist die Teilnahme an VA 5.02.040 02.05. -13.05.2005 oder n.V., ganztägig, Vorbesprechung: 03.02.2005, 13:00, W04 0-098, n. V.


Fortgeschrittenenpraktikum Versuche 12 - 15 (Blockpraktikum) Psychophysik. Neurosensorik und auditorische Signalverarbeitung (PR, E). Die erfolgreiche Teilnahme entspricht vier Versuchen im F-Praktikum. Teilnehmerzahl: 12. Die Verteilung der Praktikumsplätze auch für die Blockpraktika findet am 1. Termin des Seminars zum F-Praktikum statt. Zwei Wochen ganztägig im September 2005. n. V.

Kollmeier / Uppenkamp / Verhey


25

Physikalische, technische und medizinische Akustik V, E, A Di 8 - 10, W02 1-156

Kollmeier

Einführung in die Medizinische Physik (Introduction to field of specialization - biomedical physics) V Fr 8 - 10, W02 1-148

Kollmeier

Medizinische Physik S, E Di 10 - 12, W02 1-143

Kollmeier

Bildgebende Verfahren V, E Mi 8 - 10, W02 1-128

Uppenkamp

Neurokognition S, E, A Di 16 - 18, W02 1-128

Uppenkamp / Verhey

Neurosensorik (Seminar des internationalen Graduierten-kollegs Neurosensory Science and Systems) S Fr 10 - 12, W02 1-143

Kollmeier u. Lehrende des Internationalen Graduiertenkollegs

3.2 Compact lab courses Compact lab course “Psychophysics and neurosensory signal processing” (institutes of physics, B. Kollmeier and J. Verhey): All InterGK graduate students from Oldenburg attend this two-week-intensive lab course that provides an introduction to psychoacoustics measurements and modelling techniques as well as some basic neurosensory experiments (e. g., EEG experiments with audio and video input, reaction time measurement, fMRI experiments). In the first week, the mornings are reserved for lecture/seminar (with ample time for discussion in a small group of students and direct interaction between the instructor and the students). The afternoon in the first week are reserved for pre-assembled experiments providing a broad overview of experimental techniques used in psychophysics and neurosensory research. The second week provides the opportunity to perform one from a list of six little projects each with two students and one or two supervisors in order to look a bit deeper into special domains. Typical projects are:

o FMRI contrast for melodic/not melodic auditory perception o The psychoacoustics of the auditory throne at the house of hearing o Psychoacoustical experiments on the sensitivity to spectro-temporal

receptive fields o Psychoacoustics of dynamic loudness perception o Binaural experiments and modelling o Psychoacoustics of auditory object binding mechanisms o Binaural EEG o Psychoacoustics of amplitude modulation o Otoacoustic emissions and fine structure of the absolute threshold o Phase effects in loudness perception of complex tones and it relation to

basilar membrane movements o Comparison of distortion-product-otoacoustic-emission (DPOAE) growth-

function with suppressor and loudness growth functions o Source separation of the two sources of the DPOAEs via latency windowing

3.3 Seminar of the graduate school Each Friday during the teaching term, the students were required to attend the seminar of the InterGK where either the graduates presented their work or external speakers were invite (see program encl.). In the latter case, a special discussion session is organized (mostly after the talk) where only the speaker and the graduates are allowed to participate (and not the heads of the respected departments in order to encourage lively discussions with the graduates). Both the talk and the discussion rounds are prepared by the graduates in a self organized manner: The graduate who invites and hosts the


26

speakerdistributes the most relevant literature related to the guest scientist’s work and also leads thei discussion in an internal seminar of the graduates. Hence, the graduates are well-prepared for the talk and for the subsequent discussion. Date Speaker Title 24-May 2002 Richard O. Duda, CIPIC

Interface Laboratory University of California, Davis

Structural HRTF Models for Spatial Sound Synthesis

06-Jun 2002 Dr. Thomas Euler, MPI für Medizin, Heidelberg

Direction-selective calcium signals in dendrites of starburst amacrine cells

19-Jun 2002 David Gelbart, ICSI Berkeley

Automatic Speech Recognition Without a Close Microphone

12-Jul 2002 Dr. Otto Gleich, HNO-Klinik, Universität Regensburg

Seminar: Entwicklung und altersbedingte Veränderungen im Hörsystem der Wüstenrennmaus

08-Aug 2002 Dr. Christian Leibold, HU Berlin

A theory on the neural representation of ITDs in small mammals based onsynaptic learning

21-Aug 2002 Prof. George Sperling, UC Irvine, USA

Three systems theory of human visual motion perception

25-Oct 2002 Hynek Hermansky , Oregon Health University, U.S.A.

Automatic speech recognition

01-Nov 2002 Stefan Uppenkamp fMRI of the auditory system 08-Nov 2002 Petra Arndt Intersensory interaction in eye and arm 14-Nov 2002 Jesko Verhey

Ulrike Langemann CMR - Human and animal psychophysics

15-Nov 2002 Ian Winter, CNBH, Cambridge/UK Georg Klump

Physiological bases of CMR

22-Nov 2002 José Ignacio Vallines Garcia

Is perisaccadic striate cortex activity due to shifting attention?

28-Nov 2002 Zoe Kourtzi, MPI Tübingen Shape processing in the monkey and the human brain

29-Nov 2002 Bodhisatya Sarker Low Power Design Methodology / Relation to Neurosensory Systems

10-Jan 2003 Mailin Segger-Junius, Uni Hamburg

Characterization of the dendritic transport of shank1 mRNA

17-Jan 2003 Erich Schröger, Univ. Leipzig

Zusammenhänge zwischen automatischer Veränderungsdetektion, Distraktion und Arbeitsgedächtnis

23-Jan 2003 Oliver Fobel Disputation: "Auditory brainstem and middle-latency responses with optimized stimuli: Experiments and models"

24-Jan 2003 Melanie Zokoll Wie hören Schleiereulen spektrale Muster?

31-Jan 2003 Miguel Angel Garcia Perez, U. Complutense, Madrid

Adaptive Bayesian Estimation


27

05-May 2003 Volker Hohmann Signalverarbeitung für Hörgeräte: Akustische Grundlagen und psychoakustische Modelle

08-May 2003 Manfred Radmacher, Universität Bremen

Untersuchung zellulärer und molekularer Prozesse im Kraftmikroskop

09-May 2003 Frank Bremmer, Univ. Marburg

Space representation in posterior parietal cortex

15-May 2003 Gabriele Grenningloh, Univerité de Lausanne

Dynamische Regulation des Zytoskeletts

16-May 2003 P. Heil, Leibnitz-Inst., Magdeburg

Time processing in the auditory system

28-May 2003 Frans Zwarts, RUG, Groningen

Current Status and Trends in Ph.D. Education in the Netherlands

06-Jun 2003 Richard Kempter, Humboldt-Universität Berlin

Neural models of the auditory system

13-Jun 2003 Bodhisatya Sarker Source code transformations 19-Jun 2003 Sabine Windmann, Ruhr -

Universität Bochum Top Down processes in perception and memory

20-Jun 2003 Frank Schütte Retinoic acid binding proteins in the retina

26-Jun 2003 Peter Narins, UCLA Los Angeles

Frequency-dependent acoustic pathways in the amphibian ear: Evidence from models, measurements and microseismic stimulation

27-Jun 2003 new scholarship holders short presentations 03-Jul 2003 Heinrich Bülthoff, MPI

Biokybernetik, Tübingen Virtuelle Welten: Ein neuer Weg zur Erforschung des Gehirns

04-Jul 2003 Johannes Nix Sequential Monte Carlo methods as model for multimodal integration

11-Jul 2003 Annika Akerfelt EEG stop signal experiment 17-Jul 2003 Carola Meier, Ruhr -

Universität Bochum Glial gap junction: Molecular make-up, ultrastructure, function and inhibition

18-Jul 2003 H. Maier, Univ. Hamburg Potassium recycling in the cochlea 17-Oct 2003 Steven Greenberg, ICSI

Berkeley, USA Whither Speech Technology? - A Twenty-First Century Perspective

24-Oct 2003 Melanie Zokoll Auditory memory in songbirds 31-Oct 2003 Claudia Steinbrink Phonological and inflectional errors in

German child language 6-Nov 2003 Maki Ikebuchi, Univ.

Bielefeld Behavioral and Neuroanatomical Studies of Auditory Memory in Birds

13-Nov 2003 Kirsten Wagener Speech Intelligibility in Noise (Disputation)

13-Nov 2003 Thomas Münte, Univ. Magdeburg

Attentive und präattentive Prozesse beim menschlichen Hören

14-Nov 2003 Reto Weiler Recent developments in visual prostheses

21-Nov 2003 Jesko Verhey et al. Spectro-temporal modulation processing


28

24-Nov 2003 M. Vorländer, RWTH Aachen

Raumakustische Simulationen – Möglichkeiten und Grenzen

28-Nov 2003 Georg Klump Neurosensory Science: quo vadis? 4-Dec 2003 Benedikt Grothe, LMU

München Erfahrungsabhängige Entwicklung von Mechanismen der Schallokalisation bei Säugern

11-Dec 2003 Marc Spehr, Univ. Bochum hOR17-4 - one receptor, dual capacity 12-Dec 2003 Hans Colonius Metric from discriminability 18-Dec 2003 Marten P. Smidt, Univ.

Utrecht Genetic factors involved in the development of the mesencephalic dopaminergic system

08-Jan 2004 Thomas Münch, University of California Berkely

Directional selectivity in the retina

9-Jan 2004 Riklef Weerda Neural correlates of visual attention 15-Jan 2004 Enrica Strettoi, CNR

Neurophysiology, Pisa, Italy

Remodeling of inner cells in Retinitis Pigmentosa: lessons from transgenics and knock out

16-Jan 2004 Volkmar Hamacher, RWTH Aachen/SAT Erlangen

Signalverarbeitungsmodelle des elektrisch stimulierten Gehörs

22-Jan 2004 Eckart Gundelfinger, IFN, Magdeburg

Transmitterfreisetzung aus Synapsen des Zentralnervensystems: Die molekulare Organisation der aktiven Zone

23-Jan 2004 Annika Akerfelt Inhibition of action 29-Jan 2004 A. Reichenbach, Paul-

Flechsig-Institut für Hirnforschung, Universität Leipzig

Die Rolle der Müllerzellen für Struktur und Funktion der Retina

30-Jan 2004 Miyuki Morioka Hand-arm vibration perception (to be confirmed)

05-Feb 2004 Christian Lohmann, MPI Neurobiologie, München

Wie Nervenzellen Kontakt aufnehmen: Regulation dendritischer Plastizität durch Calcium-Signale während der Synapsenbildung

6-Feb 2004 Karin Klink Discrimination of duration 23-Apr 2004 Stefan Strahl Efficient Representation of Natural

Sounds 29-Apr 2004 Suzan Emiroglu Similarity rating and JND measurements

on timbre perception in hearing-impaired and normal listeners

30-Apr 2004 R. Mühler , U. Magdeburg Auditory evoked potentials 7-May 2004 Julia Maier Directional hearing in Gerbils 14-May 2004 Suzan Emiroglu Timbre Perception and hearing loss 24-May 2004 SFB-Meeting 4-Jun 2004 Tübingen Excursion (Departure: 3-June) 11-Jun 2004 Sandra Buss Perception of tyre road noise 18-Jun 2004 O. Güntürkün, Univ.

Bochum From Vision to Emotion

25-Jun 2004 Jennifer Shelley Horizontal cells in the mouse retina 9-Jul 2004 Dirk Junius Binaurally evoked auditory potentials


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25-Aug 2004 Jutta Kretzberg, University of San Diego, California

Latenz-basierte retinale Kodierung visueller Stimuli bei Augenbewegungen

04-Sep 2004 Rüdiger Wehner, Zoologisches Institut der Universität Zürich, Schweiz

Navigation in insects

29-Oct 2004 Marc Nitschmann Modelling the Inattentive Observer 05-Nov 2004 Kajsa Danielsson, KTH

Stockholm Noise estimation in a speech recognition system using a-priori knowledge

05-Nov 2004 Ronny Meyer Short presentation of his diploma thesis 11-Nov 2004 Bernd Ronacher, HU Berlin Variability of spike trains: consequences

for the processing of acoustic signals in grasshoppers

18-Nov 2004 Dr. Marlene Bartos, Universität Freiburg

Shunting inhibition promotes synchronized gamma oscillations in hippocampal interneuron networks

25-Nov 2004 Melitta Schachner, Zentrum für Molekulare Neurobiologie, Hamburg

Recognition molecules and the rejuvenating nervous system

26-Nov 2004 Rainer Beutelmann Binaural Speech Intelligibility Prediction 03-Dez 2004 Udo Ernst, Univ. Bremen Principles of contour integration in the

human brain – one-way roads for neural activities?

09-Dez 2004 Prof. Dr. Roland Brandt, Neurobiologie, Universität Osnabrück

Zytoskeletale Mechanismen bei der Degeneration von Nervenzellen in der Alzheimerschen Krankheit

10-Dez 2004 Michael Buschermöhle Neuronal Mechanisms of Detection And Segregation of Modulated Auditory Signals

16-Dez 2004 Rainer Klinke, Universität Frankfurt

Angeborene Gehörlosigkeit: Das Erwecken des auditorischen Cortex durch Cochlea-Implantate

03-Jan 2005 Jesko Verhey Mechanismen bei der akustischen Objektbildung – oder warum man gleichzeitig verschiedene Dinge hören kann

07-Jan 2005 Daniel Pressnitzer, Ecole Nationale Superior, Paris

From pitch to timbre, in normal hearing and cochlear implant listeners

13-Jan 2005 Eckard Altenmüller, HMT Hannover

Processing of Emotions in Music

14-Jan 2005 Ronny Meyer Grundfrequenzerkennung mit SMC 20-Jan 2005 Alexander Borst, MPI für

Neurobiologie, München Behind the facette eyes: complex receptive fields of fly motion-sensitive neurons

21-Jan 2005 Erich Schröger, Univ. Leipzig

Pre-attentive deviance detection and its relation to auditory memory and distraction

27-Jan 2005 Christian Kaltschmidt, Institut für Neurobiochemie, Witten/Herdecke

Role of transcription factor NF-kB in the the nervous system


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28-Jan 2005 J. Esther C. Wiersinga-Post, RU Groningen

Missing fundamental vs. spectrally cued pitch. Psychophysics and brain imaging

01-Feb 2005 T. Marquardt, UC London How does the mammalian brain code for binaural information?

03-Jan 2005 K.-H. Smalla, Leibniz-Institut für Neurobiologie, Magdeburg

Association of neuroplastin-65 to postsynaptic densities depends on synaptic activity

04-Feb 2005 Jennifer Shelley Electrical Synapses in the Retina 10-Feb 2005 Peter Ahnelt, Universität

Wien Das Photorezeptormosaik der Säugetiere als Spiegel ihrer visuellen Evolution und Ökologie

11-Feb 2005 Christine Koeppl, TU München

Neural phase locking as a temporal code in sound localization: implications for the current discussion about neural processing of interaural time differences

10-Mar 2005 Séverine Durand, Smith-Kettlewell Eye Research Institute, San Francisco

Properties of response suppression in the primary visual cortex

29-Apr 2005 Suzan Emiroglu Similarity rating and JND measurements on timbre perception in hearing-impaired and normal listeners

13-May 2005 Sandra Buss Perception of tyre road noise 20-May 2005 Michael Buschermöhle A Review of Spike Sorting: Methods and

Applications 27-May 2005 John Dylan Hayns, UCL

London Consciousness in fMRI

27-May 2005 Gerke Hoiting Measuring MRI noise 03-Jun 2005 InterGK Meeting on InterGK continuation

request 10-Jun 2005 Peter König, Univ.

Osnabrück Sparse coding in vision

17-Jun 2005 Rike Steenken Project presentation 17-Jun 2005 Stefan Heise Project presentation 24-Jun 2005 + 01-Jul 2005

Julia Maier Melanie Zokoll Marc Nitschmann

Sound localization in impared systems Auditory short-term memory Spectral effects in binaural signal processing

08-Jul 2005 Stefan Strahl Sparse coding in audio 14-Jul 2005 Nils Brose, MPI Exp.

Medizin, Göttingen The role of Neuroligins in synaptogenesis and synapse function

3.4 Regular exchange seminar Groningen-Oldenburg On a regular monthly basis (usually the first Monday of each month) the joint Groningen/Oldenburg seminar took place in an alternating sequence between Oldenburg and Groningen. Each InterGk student was requested to attend this seminar. During the first half of the granting period, the seminar circulated among the different research groups participating in the InterGK, so that each research group had the chance to give an overview of their respective research activity, provide a lab visit, and give their respective


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Ph.D. students the chance to present their work in front of a comparatively large and knowledgeable audience. In the second half of the granting period the attempt was made to have more theme-oriented half-day-workshops (again hosted by the different research groups in a circulating manner) where both external talkers and talkers from the respective other university were invited. This provided a broad overview of the individual groups research activities and their prime collaborations in the field. A table of contents for the seminar is given below. 3.5 Monthly meetings of all EuroGK-members (Groningen and Oldenburg)

Date Location 24-Jun 2002 Lab Tour Zoophysiology & Behaviour Group (Oldenburg)

with an introductory lecture by Ulrike Langemann and Georg Klump: Animal models in auditory research: psychoacoustics and physiology

18-Nov 2002 Computer science department HPC/V - HuQ Speech recognition (Groningen) Welcome, introduction by Nicolai Petkov demonstration Reality Center (visualisation facilities) Peter van Hengel: Human quality speech recognition Michel Westenberg: contour detection in psychophysical experiments and its relation to non-CRF inhibition (psychophysics and computational modelling) Cosmin Grigorescu: improved automatic contour detection by employment of surround inhibition Remco Renken: Effectiveness of motion related "noise" reduction in fMRI. Alle Meije Wink: Denoising in functional neuroimaging: wavelet denoising as an alternative to Gaussian smoothing. Final discussion

9-Dec 2002 Day workshop "Spectro-temporal features - Physiology, Psychoacoustics and Applications" (Oldenburg) David Klein (ETH Zürich) Spectrotemporal auditory receptive fields in neurophysiology Christian Kaernbach (Universität Leipzig): "Spectro-temporal representations of elementary auditory percepts" Hynek Hermansky (OGI, Portland, Oregon) "Getting rid of bad-bad short-term spectral envelope in automatic speech recognition" Michael Kleinschmidt (Universität Oldenburg) "Spectro-temporal Gabor features for robust automatic speech recognition" Volker Hohmann (Universität Oldenburg) 'Modulation transfer functions of dynamic compression hearing aids'

10-Feb 2003 Lab Tour "PET Center" (Groningen) Introduction PET-Center (W.Vaalburg) PET-instrumentation (A.M.J. Paans) PET-Radiopharmaceutical preparation (P.H. Elsinga) DATA acquisition and modelling (A.T.M. Willemsen Receptor studies (A. van Waarde) Neuroimaging of language (L.A. Stowe)


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Clinical Neuro PET (J. Pruim) Pgp function in the blood brain barrier (N.H. Hendrikse) Gene therapy and brain tumors (E.F.J. de Vries) Visit PET-Center

10-Mar 2003 Lab Tour "Komplexe Systeme" and "House of Hearing" (Oldenburg) Welcome (U. Feudel, B. Kollmeier) U. Feudel: Dynamical transitions in complex systems: What have neurons and ecological systems in common? T. Brand: Modelling of speech perception in noise Tour ICBM and Coffee S. Uppenkamp: Representation of peripheral neural activity in the middle-latency evoked field from primary auditory cortex in humans. B. Kollmeier: Activities in the new "House of Hearing"

28-Apr 2003 Lab Tour "Speech and Hearing" (Groningen) Welcome by Gert ter Horst, director of BCN Gerke Hoiting: Predicting sound production in fMRI Peter Hengel: the use of features in incident-detection and speech recognition Sietze van Netten: Accuracy of mechano-electrical transduction in hair cells Emile de Kleine: the cochlear implant Labvisit KNO, Hero Wit

22-25 May 2003 Excursion of the InterGK to Kopenhagen 23-Jun 2003 Symposium (Groningen): "Brain plasticity and critical periods" 07-Jul 2003 Lab Tour fMRI (Oldenburg)

Mark Greenlee Welcome, opening remarks Roland Rutschmann Functional MRI and post-processing Ignacio Vallines Visual stimulation and eye-movements in fMRI Jale Özyurt fMRI of the saccadic system Guided tour of the MR facilities in Klinikum Oldenburg

04-07-Sep 2003 InterGK summer school in Odoorn/NL 06-Oct 2003 Lab Tour (Oldenburg) "Signal Processing in optical and acoustical

communication" Welcome and short Introduction (A.Mertins, B. Kollmeier) Prof. Dr. Alfred Mertins: "Engineering aspects of image and audio coding" Rainer Huber "PemoQ: Audio Quality assessment using an auditory model" Heiko Gölzer "Importance of early and late reflections for Automatic Speech Recognition" Poster Presentation Jun.-Prof. Dr. Jesko Verhey: "Signal Processing models of psychoacoustics and auditory physiology" Lab Tour Medical Physics/Acoustics/Signal Processing group

03-Nov 2003 Lab Tour Groningen, Animal Behaviour, Circadian rhythms research Prof. Serge Daan Introduction to circadian rhythms research in Groningen. Dr. Roelof A. Hut Circadian rhythms: the input pathway under investigation. Drs. Kamiel Spoelstra Circadian rhythms: current investigations on the clockwork.


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Dr. Peter Meerlo Circadian rhythms and stress: neurobiological aspects. Drs. Barbara Biemans Circadian rhythms in learning and memory: neurobiological aspects. Dr. Domien Beersma Circadian rhythms in behaviour: sleep regulation. Dr. Marijke Gordijn Circadian rhythms in humans: investigating advanced and delayed sleep phase syndromes.

01-Dec 2003 Lab Tour (Oldenburg) Psychophysics (Acoustics and Vibration): From Basic Research To Application Welcome from Volker Mellert "Sound and Vibration in the Aircraft Cabin" - Roland Kruse "Basic experiments on the perception of vertical whole-body vibrations" - Michael Bellmann Vibrotactile thresholds, Darren Whitehouse, guest speaker from Institute of Sound and Vibration Research University of Southampton "Equal Vibrations Level Contours at the fingertip and hand-palm" - Handy Oey Lab Visit of the acoustic group

12-Jan 2004 Lab Tour (Groningen) Measuring and Modelling Perception Just van Es (Ophthalmology, RUG, NIC) :fMRI of Brightness Perception Tony Vladusich (Ophthalmology, RUG, NIC): Modelling Brightness Perception Jeroen Benjamins (Psychonomics, UU): Parietal acti vations during judgements of brightness Nicolai Petkov (Institute of Mathematics and Computing Science, RUG): Non-classical receptive field inhibition and contour detection Hans van Hateren, (Neurobiophysics , RUG): Processing of natural temporal stimuli by retinal ganglion cells Esther Wiersinga, (Biomedical Engineering, RUG, NIC): Integration of auditory and visual information; psychophysics of the McGurk effect. Wei Ji Ma (Princeton): Humans integrate and segregate auditory and visual information in a statistically optimal fashion. Lab tour of the 3T MR and various EEG facilities

02-Feb 2004 Psychophysics and auditory modelling (Jesko Verhey, Oldenburg) "Introduction to the Perception of amplitude modulation" - Jesko Verhey " Neural model of amplitude modulation processing " - Ulrike Dicke " Modulation processing and auditory grouping " - Stephan Ewert (DTU, Kopenhagen) Lab Tour

01-Mar 2004 Hibernation, sleep and neuronal connectivity (Groningen) Dr. Roelof A. Hut, Animal Behaviour, Groningen: Hibernation and behavioural rhythms. Dr. Christian Bock, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven: Investigating brain energy supply during hibernation with NMR. Dr. Eddy A. van der Zee, Molecular Neurobiology, Groningen:


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Hibernation, Plasticity and Protein Kinases. Dr. Jens Stieler, Paul Flechsig Institute for Neuroanatomy, Leipzig: Hibernation as a model for Alzheimer’s disease.

17-May 2004 Auditory neurobiology (Georg Klump, Oldenburg) Frank Ohl (IFN Magdeburg): Neurodynamics in auditory cortex during category learning Mark Bee (Oldenburg): Sequential auditory stream segregation in the avian auditory forebrain "

05-Jul 2004 Visual Neuroscience (Reto Weiler, Oldenburg) Timm Schubert (UOL): Gap Junctional Coupling of Mouse Retinal Ganglion Cells is Mediated by Differential Expression of Connexins Frank Schütte (UOL):Retinoic Acid as a Modulator of Gap Junctional Coupling in the Retina Karin Dedek (UOL): Expression of Connexin45 in Bipolar Cells of the Mouse Retina Martin Greschner & Andreas Thiel (UOL): The Temporal Structure of Retinal Ganglion Cell Responses and Its Relation to Intraretinal Processing Silke Haverkamp (MPI Hirnforschung, Frankfurt) Diversity of Glycine Receptors in the Mouse Retina Thomas Euler (MPI Medizinische Forschung, Heidelberg): Two-Photon Chloride Imaging in ON-Type Bipolar Cells Expressing a Genetically Encoded Indicator

19-22 Aug 2004 Summerschool "Neurosensory Science and Systems" in Bad Zwischenahn

25-Oct 2004 Information visualisation, computer science, learning processes, image analysis and more, Computer Science (Groningen) Michael Wilkinson: Connectivity preserving filters in morphological image analysis Michael Biehl: Specialization and symmetry breaking in learning processes Michael ten Caat: EEG Visualization Drs. Ronald van den Berg: Perception-driven information visualization Prof. dr. Jos Roerdink: Brain connectivity analysis and visualization

08-Nov 2004 Audio and signal processing (Alfred Mertins, Oldenburg) Welcome and Introduction (Alfred Mertins, Oldenburg) Convolutive blind source separation for EEG data modeling (Jörn Anemüller, Oldenburg) Efficient basis representations for natural sounds (Stefan Strahl, Oldenburg) Audio Restoration (Markus Kallinger, Oldenburg) Scalable audio compression (Huan Zhou, Oldenburg)

06-Dec 2004 Butterfly vision (Doekele Stavenga, Groningen) Hair cells transduction in relation to hearing (Sietse van Netten, Groningen) Patch clamping mouse hair cells (Cecil Meulenberg, Groningen) Sensitivity regulation in the primate outer retina (Hans van Hateren, Groningen) Psychophysics of contrast gain control (Herman Snippe, Groningen)


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10-Jan 2005 Sensory Coding (Jutta Kretzberg and Jesko Verhey, Oldenburg) Jutta Kretzberg (Uni Oldenburg): "Population coding in the mechanosensory system of the leech" Anne Kathrin Warzecha (Unis Bielefeld / Muenster): "On the reliability of encoding visual motion information" Jan Benda (HU Berlin): "Spike-frequency adaptation separates transient communication signals from background oscillations in weakly-electric fish" Jesko Verhey (Uni Oldenburg) "Temporal representation of pitch on the level of the mammalian cochlear nucleus"

22-Mar 2005 – 24-Mar 2005

Visit from the Graduiertenkolleg GKKN Tübingen Georg Klump: Begrüßung + Vorstellung InterGK Oldenburg Henrik Mouritsen (Animal Navigation) Ulrike Langemann (Tier-Psychoakustik) Suzan Emiroglu (Mensch-Psychoakustik, Klangfarben) Stefan Uppenkamp + Riklef Weerda (FMRI) Petra Arndt (ADHS) Jennifer Shelley (Visuell, Retina) Michael Buschermöhle (Modellierung: Signal detection in comodulated noise) Volker Mellert (Health Effects in Aircraft Cabin Environment) Laborführungen in 2 -3 Gruppen (Biologie, Psychologie, Haus des Hörens)

04-Apr 2005 Hearing Research, CN Neuroimaging Center (Groningen) Auke Nutma, A new speech processing strategy for cochlear implants Wiebe Horst, Input-output relations of auditory nerve fibers with low spontaneous spike rate Gerke Hoiting, Measuring MRI noise Pim van Dijk, Passive and active hearing in the amphibian inner ear Short demonstration of the Carlos lab

30/31-May 2005 Mini-Symposium: Cochlea Modeling (Oldenburg) M. Mauermann, J. Verhey (Oldenburg): Welcome, Overview + Spectral fine structure of otoacoustic emissions and temporal properties of acoustic reflex, brain stem responses and psychoacoustics – explanations from local and global views on cochlear mechanics H. Duifhuis (Groningen): Cochlear Modeling – some open issues, base, apex, and ‘traveling wave’ N. Cooper (Keele): Cochlear nonlinearity – physiological measurements to test various cochlear models A. Kern (Zürich):Modeling of nonlinear hearing phenomena by Hopf amplifiers P. van Hengel (Groningen):Cochlea models in technical applications – the use of simplified cochlea models V. Hohmann (Oldenburg): A new approach of a nonlinear auditory filterbank – an alternative to physical/physiological based cochlea models? C. L. Talmadge (U. Mississippi): Cochlear Mechanics: Forward and


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reverse traveling waves in the cochlea. 13-June 2005 Eye-movements, visual search and the brain (F. Cornelissen,

Groningen) Ronald van den Berg (RUG): Feature hierarchy in visualization IWI/ OHK- Aave Hannus(RUG): Competition between features in visual search Sabine Hunnius (RUG): The development of visual scanning and disengagement of attention in infants Jale Özyurt (UOL): Eye-movements in fRMI with ADHD children performing go/nogo and memory tasks Ignace Hooge (U. Utrecht): Visual search and memory for inspected locations

04-Juli 2005 Neurosensory Information Processing: Phenomena and Models (ICBM, Oldenburg) U. Feudel (Uni Oldenburg) Welcome and Introduction J. Garcia-Ojalvo (Universitat Politecnica, Barcelona, Spain) Pitch Perception and Ghost Stochastic Resonance R. Schaette (HU Berlin) Hyperactivity through Homeostatic Scaling after Hearing Loss: A Model for the Development of Tinnitus N. Stocks (University of Warwick, UK) An Information-Theoretic and Stochastic Approach to Cochlear Implant Coding J. Freund (Uni Oldenburg) Information Processing of Noisy Neuronal Bursters

3.6 Summer schools and symposia During the current reporting period, two summer schools and several scientific meetings were organized by board members from the InterGK to provide the graduates both an intense and broad inside into the current research themes and also to encourage contacts between the graduates and international leading experts in their respective areas of research. The first summer school in Odorn/NL (September 2003) was intended as a “kick off”-meeting for the new granting period and for introducing the new graduate students to the faculty and colleagues of the InterGK. Besides talkers from both participating universities, only one external expert (Prof. David Mc Alpine, UCL London) participated. Further information is given below. The second summer school was held in Bad Zwischenahn in 2004 in connection with a symposium on “Object formation in audition and vision: Bottom-up and top-down processing”. This summer school was organized in the “classic” Oldenburg summer school format, i. e. the morning being reserved for tutorial talks by the international experts, the afternoons reserved for a poster session by the graduates or for workshops on specialized topics (6 – 8 graduates together with 2 – 4 experts discuss) or to organized lab tours (each graduate takes the most interesting international expert to his/her lab in order to discuss the research set up). The feedback both from the international experts and from the graduates were very positive. The program of the summer school is given below.

In addition, several multiple-day-workshops and scientific meetings were organized in Oldenburg, Delmenhorst or Groningen, respectively, where those graduates were invited to participate that work on closely related research items (see list below in chronological order).


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3.6.1 Symposium 2002 “Binaural Hearing at Cocktail Parties,” HWK Delmenhorst, 12-14th August 2002

(see http://www.biols.susx.ac.uk/HearNet/Hanse%20binaural/Binaural.html) (Organizers: John Culling, B. Kollmeier) Binaural displays Steven van de Par Cross-correlation versus equalization-cancellation (E-C) based

binaural displays Jeroen Breebaart A time-domain binaural model based on binaural excitation-

inhibition interaction Philip Joris Extending the binaural display John Culling Discriminating between correlations and between models David McAlpine Bending the Binaural Display Role of location Mike Akeroyd Binaural masked thresholds for complex tones and the

independence of ITD equalization at multiple frequencies Barrie Edmonds Is there a role for location in speech intelligibility in noise? Adelbert Bronkhorst Identification of features of synthetic vowels presented with and

without distracters. Doug Brungart Adaptation to Target Transitions in the Cocktail Party Problem Richard Freyman When does informational masking of speech occur and how can it

be overcome? Realistic listening environments and applications Barbara Shinn-Cunningham

Ignoring the speaker right in front of you: A natural cocktail party task.

Birger Kollmeier The simulated cocktail party for audiological purposes: Facts, Factors and Illusions

Ruth Litovsky The cocktail party in adults and children: Effects of competitor location and type

Modelling real listening Kalle Palomaki A binaural processor for missing data speech recognition in the

presence of noise and small-room reverberation Douglas Campbell Binaural sub-band adaptive noise cancellation - some results Volker Hohmann Cocktail party processing based on interaural parameters David Banks Some features of speech in a two channel voice localisation system Steve Holmes Effects of duration on double vowel identification

3.6.2 Symposium: Pitch: Neural Coding and Perception", August 14 - 18, 2002, Hanse-Wissenschaftskolleg Delmenhorst

(Organizers: Chris Plack, Andy Oxenham, Torsten Dau) Chris Plack Psychophysical studies of pitch Bill Hartmann Effects of mistuned harmonics Bill Yost Iterated ripple noise and the role of temporal fine structure in

auditory Processing Christian Kaernbach Pitch of unresolved harmonics: Evidence against autocorrelation Chris Darwin Pitch and grouping Brian Roberts Spectral fusion, global pitch, and partial pitch John Culling Binaural pitch Brian Moore Pitch perception in the hearing impaired Bob Carlyon Perception of pitch by cochlear implant users Bertrand Delgutte Physiology of pitch


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Ian Winter Periodicity tuning in the cochlear nucleus Benedikt Grothe Does the mammalian brain encode periodicity? A controversy Xiaoqin Wang Pitch representations in the primate auditory cortex Holger Schulze Periodicity coding in the gerbil auditory cortex and the perception

of pitch Alain de Cheveigné Models of pitch perception Ray Meddis A computational model of pitch extraction in the auditory brainstem Roy Patterson Time-interval models and the domain of musical pitch Shihab Shamma Place and template models of pitch William Shofner Comparative studies of pitch Tim Griffiths Functional imaging of pitch processing Robert Zatorre Pitch representations and musical imagery Evan Balaban & Aniruddh Patel

Dynamic neural correlates of human pitch and tone sequence perception recorded with magnetoencephalography (MEG)”

Emmanuel Bigand & Barbara Tillman

Effect of context on the perception of pitch structures in music

Daniel Levitin Understanding absolute pitch: An integrated review Eckart Altenmuller Physiological representations of music

3.6.3 Symposium 2002 “The Cognitive Neuroscience of Individual Differences - New Perspectives” HWK Delmenhorst, 7.-9. Nov 2002

(Organizers: Prof. Dr. Ivar Reinvang, Prof. Dr. Manfred Herrmann, Prof. Dr. Mark Greenlee)

Stein Andersson, Sunnaas Sykenhus, Nesoddtangen, Norway

ERP correlates od individual differences in neuropsychological function

Carles Escera, University of Barcelona, Spain

ERP and behavioural indices of healthy and impaired involuntary attention

John Fossella, Weill Medical College of Cornell University, New York

Genetic susceptibility to attentional deficits

Helge Nordby, University of Bergen, Norway

ERP correlates of individual differences in neuropsychological function

Ivar Reinvang, University of Oslo, Norway

ERP (P3) and neuropsychological performance – the role of attention

Kjetil Sundet, Rikshospitalet University Hospital, Oslo, Norway

ERP correlates of individual differences in neuropsychological function

3.6.4 Summerschool 2003, September 4th – 6th in Odoorn, NL: Parallels in visual and auditory processing : Adaptation and localization

(Organizers: Rob Visser, Diek Duifhuis, Birger Kollmeier) Thursday 11.00 (theme 1) Herman Snippe models of adaptation

in the sensory system 12.00 lunch 13.30 (theme 1) Felix Wichmann Contrast Transfer in

Human Vision


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14.30 workshop theme 1 (3 parallels) every group makes 7 questions/statements for the panel (3

parallels)

15.15 tea 15.45 workshop adaptation

• Weber-Fechner-law, adaptation and dynamics in audition and vision

• Modulation transfer function concept for assessing adaptation

• Biophysical and cellular mechanisms of adaptation in vision and audition

18.00 diner 19.30 evalution theme 1 paneldiscussion (panel with 2 phd’s or seniors from every

group)

21.00 bowling Friday 9.00 (theme 2) David Mc Alpine A new model of

sound localisation 10.00 coffee break 10.30 poster session 12.00 lunch 14.00 bicycle tour 18.00 diner 19.30 Jaap Korf perception in

psychiatric disorders Saturday 8.30 workshop localization

• Localization of movements in audition and vision • Head-centered and body-centered coordinate systems:

Localization features and computational properties of the visual and auditory system

• Neurobiology, psychophysics and models of localization in audition and vision

10.00 coffee 10.30 workshop theme 2 every group makes 7 questions/statements for the panel (3

parallels)

paneldiscussion (panel with 2 phd’s or seniors from every group)

11.00 panel discussion; conclusions 12.30 lunch 13.30 goodbye


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3.6.5 Summerschool 19.-22. 8. 2004: Object formation in audition and vision: Bottom-up and top-down processing Summerschool of the International Graduate School Neurosensory Science and Systems:

“Object formation in audition and vision: Bottom-up and top-down processing” Bad Zwischenahn, Germany, Bildungsstätte der Arbeitnehmerkammer Bremen, Zum Rosenteich 26, http://www.bildungsstaette-

badzwischenahn.de/html/anfahrtskizze.html Thursday, Aug. 19th Friday, Aug. 20th Saturday, Aug. 21st Sunday, Aug. 22nd

Time Visual and auditory processing: parallels and interaction

Binaural and spatial hearing Modulation and object perception Models & Applications

9.00 - 9.30B. Kollmeier Welcome&Introduction B. Shinn-Cunningham Bottom-up and

top-down influences of auditory spatial processing

H. Hermansky Beyond short-term analysis of dynamic acoustic signal

S. T. Neely Model of Auditory Perception

9.30 -10.00K. R. Gegenfurtner Processing of natural stimuli in the visual system

J. Culling Binaural unmasking in complex listening environments

M. Lewicki Theoretical models for the neural coding of natural sounds

N. Dillier Spectral and temporal compression for the hearing impaired using the sinusoidal speech model

10.00 -10.30T. Münte Event-related brain potentials and functional neuroimaging in the investigation of intramodal and crossmodal selective attention in audition and vision

P. Ungan Evoked Potential Studies on Sound Lateralization

D. McAlpine Dynamic coding of sound intensity

T. Irino Processing of Scale information in the Auditory System - Analogy to Visual Processing?

11.15 -11.45C. Büchel Crossmodal interactions investigated with functional neuroimaging

D. Tollin The psychophysical and physiological bases of the precedence effect and echo threshold

J. Verhey Comodulation masking release in the mammalian cochlear nucleus

J. M. Festen Review on speech perception in fluctuating noise

11.45 -12.15F. Wichmann Amplitude-modulated maskers in vision and hearing: parallels and differences

F. Ohl Neurodynamics In Auditory Cortex During Category Learning

J. Wouters Noise reduction approaches for improved speech perception

12.15 -12.45A. Kohlrausch Perceptual consequences of asynchrony in audio-visual stimuli

J. van Opstal Non-acoustic factors in human sound localization

Final Discussion and Moving to the House of Hearing

12.45 -14.30 Lunch Break & Discussions 14.30 -15.00Poster I: Graduates present their work Workshops II H. Schulze Periodicity coding in the auditory

cortex and its possible role in cocktail-party situations

Reception (with special acoustical effects) and Barbecue Party at the House of Hearing

15.00 -15.30Poster II B. Roberts Spectral pattern, grouping, and

the pitches of complexes and their components 15.30 -16.00Poster III 16.45 -17.15Workshops I: (Prepared) discussions

between graduates and invited guests Posters A. Rupp Auditory evoked fields mirror

psychoacoustic loudness scales, and simulated auditory nerve activity in masking period patterns of Schroeder phase complexes

17.15 -17.45 A. Oxenham Pitch perception and grouping in hearing-impaired and cochlear-implant patients

17.45 -18.15 T. Dau Effects of object formation in comodulation and binaural masking release

(Voluntary) visit of the Casino Boat tour & Eel dinner Evening without schedule


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3.6.6 Symposium 23.-24. August 2004: First Hanse Workshop of HEARing Research at the HWK: Auditory scene analysis and speech perception by human and machine"

(Organizers: Chris Darwin, John Culling) Harmonicity constraints in music and speech Anssi Klapuri, Tampere University, Finland

Pitch analysis of polyphonic music signals

Manuel Davy, IRCCYN, Nantes

Bayesian Harmonic models for music analysis

Christophe Micheyl, MIT, Cambridge MA

Segregating harmonic complexes from a harmonic or inharmonic background

John Culling, University of Cardiff

Evidence for a cancellation mechanism in perceptual segregation by differences in F0

Alain de Cheveigné, IRCAM, Paris

The case of the missing delay line

Spatial constraints and attention Barbara Shinn-Cunningham, Boston University

The role of spatial cues in segregating and understanding competing sources

Thomas Brand, Oldenburg

Modelling binaural speech intelligibility in rooms for normal-hearing and hearing-impaired listeners

Doug Brungart, WPAFB, Ohio

Acoustic factors that influence the informational masking of speech

Rhodri Cusak, MRC CBU, Cambridge, UK

Auditory scene analysis and attention

Poster session with refreshments Forming auditory objects Brian Roberts, University of Birmingham

Asynchrony and context in auditory grouping

Andrew Oxenham, MIT, Cambridge MA

The role of envelope fluctuations and fundamental frequency in speech perception and segregation using simulated cochlear-implant processing

Paris Smaragdis, MERL, Cambridge MA

Auditory object discovery using non-negativity constraints

Speech Recognition Martin Cooke, University of Sheffield

Glimpsing speech

Sam Roweis, University of Toronto

A Segmental Model of Speech Waveforms

DeLiang Wang, Ohio State University

Auditory segmentation and unvoiced speech segregation

Hynek Hermansky, IDIAP, Martigny

Linguistic code from probabilities of acoustic events

Birger Kollmeier, Oldenburg

Optimal features for speech recognition


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3.6.7 Symposium 11.-13.August 2005: 2nd Hanse Workshop of HEARing Research at the HWK “Sensory worlds: a comparative view on sensory perception”

(Organizer: G. Klump) Georg Klump Introduction to the workshop Christoph Schreiner

Coding of Dynamic Sounds in Primary Auditory Cortex: Maps and Mechanisms

Christian Machens

Flexible control of mutual inhibition: A neural model of two-stimulus-interval discrimination

Andreas Engel Possible role of fast oscillations in visual and auditory processing Marc de Lussanet Perceiving Biological Motion: From Visual Integration to Understanding

a Motor Act Poster session Silke Sachse Odor coding and processing in the honeybee antennal lobe André Fiala Dissection of a sensory circuit: olfaction and olfactory learning in

Drosophila Andreas Herz Testing the Efficiency of Sensory Coding with Optimal Stimulus

Ensembles Ben Godde Coding principles, dynamics, and adaptivity of somatosensory cortical

processing David McAlpine Population coding for sound level adapts with stimulus context Andrew King Neural coding for auditory space: from maps to spike timing Clifford Keller Localization and identification of concurrent sounds in the owl’s

auditory space map John Middlebrooks

Auditory Spatial Representation by Opponent Populations of Panoramic Neurons

Bertrand Delgutte Neural representations of pitch: Simultaneous complex tones Georg Klump Auditory streaming in the songbird brain Andrej Kral Deprivation and Development: The organization of a naive auditory

cortex 3.7 Courses for „soft skills“ The students were encouraged to participate in the following courses:

- Two-day Workshop on team development in projects of the contents: moderation of groups and meetings, roles in teams and communication. The training included theoretical aspects and exercises in form of role-playing games. The Workshop has been carried out by the part-time coach Ronny Meyer.

- Medien- und Kommunikationstraining “Das Wissen der Forschung – verständlich für Laien”, Hamburg, 19. – 20.07.2005, Dr. Ludwig Kürten, with support from the DFG

3.8 Qualifying phase for qualification stipends According to the grant proposal, the qualification stipends were requested to allow students of the bachelor/master study program “engineering physics” to enter the InterGK (first year of the previous granting period) and students from the new bachelor/master program (before: FH-Diplom-) program to qualify directly from the bachelor (or FH-Diplom) for the Ph. D. phase by attending additional courses. This stipend should allow the


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stipendiat within one year to have approximately the same level as a master student/Diplom-Student who enters the dissertation phase after passing the master exam/Diplom. Since the master program both in engineering physics and in “Hörtechnik und Audiologie” is already well structured and available, it was advisable that the qualification stipends should primarily attend those courses from the master program that are mostly required for the individual, but still have a fair distribution of the courses across subjects. The first qualification stipend, Prashant D’Souza, finished this phase by passing the master of science exam with a very high success. The other qualification stipends (to be granted in the third year of the current report period) could not be filled earlier than August, 2005 (i. e. after the current report deadline) because the study program “Hörtechnik und Audiologie” did not finish its last term until July, 2005. Even though there is no experience with this type of qualification stipend process, it is expected that no special problems will occur since – again – a well-structured master of science curriculum is available for these students from which they will select the most appropriate courses. 3.9 Transition from the previous to the current generation of Ph. D. students Due to the limited amount of stipends and a large number of associated Ph. D. students and Ph. D. students who only temporarily are awarded a stipend from the InterGK, there is no synchrony across the Ph. D.-Students with respect to beginning of their thesis work and the respective granting period of the InterGK. Only such a synchronicity in the InterGK would justify any special courses or seminars to be performed when ever a new generation of Ph. D.-Students enters the InterGK. Instead, the introduction to the InterGK took place individually for each new Ph. D.-student (primarily by the prospected supervisor of the thesis and the prospective colleagues). Even though all Ph.D.-Students are required to attend many meetings and courses during the regular lecture period, it was still possible to spend some time with the new stipendiat in order to introduce him/her into the respective lab and to show him/her the “tricks of the trade”. Hence, no special problems were reported from the transition between Ph. D.-Students generation.

4 Mentoring concept / Betreuungskonzept 4.1 Advertisement of positions The stipends were advertised in the national newspaper „Die Zeit“ with a specialized advertisement section for universities. In addition, the stipends were advertised on the web sites of the InterGK, the contributing research groups and on specialized web sites for job openings in the academic world. 4.2 Selection procedure The selection of stipendiates was performed by the board of the applicants based on the written application and – if the written application looked promising – by an oral presentation of the applicant about her/his previous scientific work and its prospects within the InterGK. Priority was given to an even distribution of positions across topics and across contributing research groups. 4.3 Supervision Each graduate was assigned to one primary supervisor and a secondary supervisor (mostly from a different, but adjacent field). The graduates performed most of their research work within the research groups of the primary supervisor and thus were very well connected to other graduate students and the technical and scientific stuff. However, the graduates from the InterGK were also very well connected within each other due to the


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regular meeting within the InterGK and the regular excursions (both to the partner university and to other university sites and special events). Also, they had a closer contact to most of the applicants/professors who also participated in the special events of the InterGK. A special role in promoting the students to become part of international networks were the summer schools that included special poster sessions where the graduates presented their work and special discussion sessions where the students were able to intensively discuss with the international experts the most relevant questions in their research work. These contacts also helped to promote the publications by the graduates either by giving additional language support (due to the presence of a native English speaker as a post-doc or due to the established connection to international experts who volunteered to pre-review the manuscripts of the graduates) or due to special issues/publications that resulted from some of the meetings and summer schools of the InterGK (e.g. summer school 2004 with an envisaged special issue of Acta acustica united with Acustica)). 4.4 Network of Ph.D. students An important part played the informal dinner meetings, which were monthly organized by the graduates in Oldenburg. In a relaxed atmosphere a strong network between the students has developed, which was very helpful for discussing new ideas, scientific problems and working conditions. Through this supportive network short questions from the fields of mathematics, computer science, physiology and alike could be directed to the student familiar to the topic and thereby quickly answered. For more difficult questions short courses have been organized (e.g. statistics and matlab). The exchanges with the Tübinger graduate school (June 2004 and March 2005) also led to a close scientific exchange between both student groups.

5 Guest scientist program /Gastwissenschaftlerprogramm Within the InterGK, there are three types of guest researcher visits:

a) Short visits (1 - 3 days): Typically, a talk is presented at the common seminar of the InterGK or at a specialized workshop organized under the auspices of the InterGK. In addition, the invited talker visits one or more research groups from the InterGK in order both to demonstrate the scientific work within the graduate school and to get into close discussion with the guest researcher. Also, there is a special discussion session organized (mostly after the talk) where only the guest scientist and the graduates are allowed to participate (and not the heads of the respected departments in order to encourage lively discussions with the graduates). Both the talk and the discussion rounds are prepared by the graduates in a self organized manner: The graduate with closest link to the invited talker distributes the most relevant literature related to the guest scientist’s work and also hosts an internal seminar of the graduates were these papers are reviewed and discussed. Hence, the graduates are well-prepared for the talk and for the subsequent discussion. Both the graduates and the applicants have made very good experiences with this kind of structured guest talker program. Even though it requires additional activity from the graduates, it pays off at the end. The name of the guest researchers can be seen from the seminar topic list (see 4. Study program).

b) Mid-term-stays (3 days up - 1 week, typically in connection with a special event, like a summer school or a series of lectures): Only a few distinguished scientists are invited to stay for an extended period of up to one week if they both are of special interest for possibly a large number of InterGK graduates and who are willing to


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spend some time with the graduates of the InterGK. In a typical summer school set up, the guest scientists give a lecture about their work in the morning (incl. Discussion), discuss the graduates´ work by inspecting and discussing the posters prepared by the graduates, and by attending special workshops/discussion groups that are focused across a certain topic. Depending on the size of the summer school, between two and twenty international guest researchers are invited to participate together with the graduates and some additional guests. This period of intense interaction between the graduates and the distinguished guest scientists has been praised a lot both by the graduates and by the guest researchers as being a very efficient and motivating way of interaction. At least one summer school and one additional event is plan for each year of the funding period. The names of the guest researchers can be seen from the programs of the respective summer schools and symposia (see Sec. 4).

c) Long-term-research-stays (1 week up to 9 months, usually associated with a stay at

the Hanse-Wissenschafts-Kolleg): Guest researchers that choose to cooperate very closely with one of the research groups associated with the InterGK have the opportunity to stay primarily with the Hanse-Wissenschafts-Kolleg in Delmenhorst which is oriented towards neuroscience and sensory systems– in addition to three other topics. This arrangement helps the guest researcher both to get support for the practical stay in the Oldenburg area (e. g. desk work environment, housing, arrangements for spouses and children, transportation) and also helps to financially support the guest scientist during his/her research stay (usually by implementing a “no loss no gain” salary arrangement, i. e. HWK pays to the guest researcher approximately the same salary as he/she would get at home). This in combination with the attractive research activities of the associated groups in the InterGK were key elements to attract very respected researcher to spend a sabbatical or parts of it at the HWK and in Oldenburg. This gives the graduates the opportunity to collaborate and discuss closer with internationally reknown guest researchers and to established a good working relation. The following fellows stayed for these long-term-research stays:

7-12/2002, 8/2004 John Culling, Cardiff Univ., Großbritannien

Binaural and spatial Hearing

10-12/2002 Hynek Hermansky, Oregon Health Univ., USA

Speech Recognition

4/2002, 10-12/2003 James P. Thomas, UCLA, USA

Cortical processing of visual information

10/ 2003 Steven Greenberg, ICSI, Berkeley, USA

Speech Technology

5-8/2004 Andrew Oxenham, MIT, USA

Auditory temporal processing

6-8/2004, 6-8/2005 David Mc Alpine, UCLondon, Großbritannien

Neuronal binaural processing

10/2004-6/2005 Galina V. Paramei, U. Magdeburg

Response time model

Typically, there are about 50 short-term-visits per year to the InterGK, 4 – 20 mid-term research stays and 1 – 3 long-term research stays per year at the InterGK.


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6 Organizational structure of the InterGK / Organisationsstruktur des Graduiertenkollegs

The Organization of the InterGK is maintained by the following bodies: a) Board of the applicants (organizational meetings of all applicants/professors of the

InterGK together with the graduates speaker (see d)): This body “rules” the InterGK and makes decisions about, e. g. acceptance or rejection of applicants for a scholarship, inclusion or exclusion of applicants/professors, coarse distribution of the budget

b) Chairman of the InterGK: Chairs the board meetings, takes care that the decisions of the board are implemented, decides about the daily business affairs within the InterGK (e. g. travel money or consumable expenditures asked for by a graduate or by a contributing group/professor).

c) General assembly ob the InterGK: Assembly of the applicants plus graduates plus associated graduates plus associated supervisors/post-docs: Council to discuss general issues of the InterGK, such as, e. g., topics for summer schools, guest researchers to be invited, special courses and workshops to be organized, excursions of the InterGK.

d) Assembly of the graduates and speaker of the graduates: The graduates meet informally to discuss, e.g., suggestions for topics for workshops, topics for special courses, topics and guest researchers to be invited to the seminar and to summer schools. These and more suggestions about the organization of the InterGK are easier to be discussed without the respective group leaders/professors. The speaker of the graduates is elected by the assembly of the graduates. Her/his task is to maintain the information flow between the graduates and the board and the speaker of the InterGK. This is done, e.g., by participating in the board meetings where he/she has the same vote as the applicants/professors (in case that the votes need to be counted).

The organization is supported by the administrative assistant (i.e. Susanne Garre) who helps and supports both the graduates, the board members and the chairman in all organizational and practical aspects. The current experience of this organizational structure from the first two granting periods is very positive.

7 Structural and organizational pre-requisites for the graduate school/ Umfeld des Graduiertenkollegs

The InterGK forms the “backbone” of the interdisciplinary “Forschungszentrum Neurosensorik” (central research organization for neural sensory science and systems) which was created during the organizational reform of the university Oldenburg in 2003: Apart from the five faculties (with the faculty II (computer science and economics) and V (mathematics and natural sciences) contributing to the InterGK), the structure of a “Forschungszentrum” allows scientists to collaborate across disciplines, institutes and across faculties under one organizational roof. Currently, there are two Sonderforschungsbereiche (SFB, i. e. special funded research initiatives) associated with the Forschungszentrum Neurosensorik:

7.1 Sonderforschungsbereich 517 “Neurokognition” (Bremen/Oldenburg):


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This SFB looks both at neurosensory processes (visual and auditory domain, mostly performed by research groups in Oldenburg) and more centrally located, neurocognitive functions involved in, e. g. emotions and action control (mostly represented by research groups in Bremen). This very successful SFB will end after its 10th year at the end of 2005. 7.2 SFB/Transregio 31 “Das aktive Gehör”: All auditory groups within the InterGK and the ”Zentrum für Neurosensorik” are also part of the newly established SFB/TR (together with the Universität Magdeburg und Leibnitz-Institut für Lern- und Gedächtnisforschung, Magdeburg). One of the research aims is to clarify the relation between bottom-up and top-town processes in evaluating the information from the auditory input. The speaker of the SFB/TR, Prof. G. Klump, is also the key person for the area “object perception” in the current InterGK prolongation proposal. In addition to the two projects conducted by G. Klump, further projects within the SFB/TR are headed by the following applicants from the InterGK: B. Kollmeier (2 projects), A. Mertins, J. Verhey , as well as projects from Dr. Ulrike Langemann (senior research associate in the Klump group) and Dr. Volker Hohmann (senior research associate in the Kollmeier group). 7.3 Kompetenzzentrum HörTech: The Kompetenzzentrum “Hörgeräte-Systemtechnik (HörTech)” at the Universität Oldenburg is funded by the BMBF and the Land Niedersachsen since 1/2002 (speaker: B. Kollmeier). This funding is the result of a national competition organized by the BMBF to grant a total of eight national centres of excellence in the area of biomedical technology. The aim of HörTech is to bundle the expertise of the universities, clinics and the industry in audiology and hearing technology with the regional focal point in Oldenburg and to perform pre-competitive research in close collaboration among these institution. Thus, a synergy exists between the fundamental research and academic training performed within the InterGK and the application-oriented research and development within the Kompetenzzentrum and its associated companies. Students entering the InterGK may come early into contact with real-world applications (which is attractive for students) and the companies might eventually offer attractive R & D positions to successful applicants of the InterGK, because they had an early encounter (which is attractive for companies). By this mechanisms, already several of the former Ph. D. students of the InterGK have meanwhile taken an attractive job offer at one of the hearing aid companies (such as, e.g., Dirk Junius, R.P.Derleth, Heike Heuermann,….). 7.4 Bachelor/Master program “Hörtechnik und Audiologie”: As a support for the special orientation at Oldenburg university into hearing research (both basic science and applied research), a cooperative Bachelor/Master program “Hörtechnik und Audiologie” has been set up across the Fachhochschule Oldenburg/Ostfriesland/Wilhelmshaven (Institut für Hörtechnik und Audiologie) and the Universität Oldenburg. The aim of the study program is to bridge technical and medical education by providing a comprehensive curriculum with all aspects of hearing within the bachelor program (managed primarily by the university of applied sciences/Fachhochschule). The best students from the bachelor program who are more oriented towards basic science may then enter the master study program (primarily managed by the Universität Oldenburg). The master in Hörtechnik und Audiologie qualifies for the promotion phase and hence is an excellent prerequisite for entering the international graduate school neurosensory science and systems. In the previous granting period, two students from this study program have been awarded a


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“Qualifizierungsstipendium” (qualifying stipend to go directly from a bachelor/FH-Diplom into the promotion phase with one year of extra course work).

7.5 Laboratory facilities in Oldenburg

Due to the institutions contributing to the InterGK listed above and due to financial support for these research institutions at Oldenburg university (both from the state of Lower Saxony and from third-party-money) the InterGK has excellent experimental facilities, e. g.: - Large anechoic room and several acoustically treated listening rooms for

performing psychoacoustical experiments - “Kommunikations-Akustik-Simulator” (communication acoustics simulator), i. e.,

a room with variable acoustics/reverberation/ apparent acoustical room size which allows to switch between different ambient acoustics conditions (such as, e. g. a cafeteria and a train station). This room at the “house of hearing” was finished in 2004 and can be used to study acoustic communication under controlled adverse acoustical conditions. It has been used in the context of the InterGK, e.g., for studying and modelling speech perception under (spatial) background noise conditions (dissertation project R. Beutelmann).

- fMRI (1,5 Tesla) at the Klinikum Oldenburg: This functional MR-scanner was acquired in 2003 and provides an adequate access for members of the InterGk to modern imaging technology. The cooperation agreement between university, Hanse-Wissenschaftskolleg and Klinikum Oldenburg allows the researchers from the Forschungszentrums Neurosensorik to access the scanner weekdays from 16 p.m. to 6 a.m. and during the weekends whole day.

- MR compatible optical position measurement system integrated into the fMRIscanner at the Klinikum Oldenburg allows the tracking of the head position during a scan and the determination of noise intensity within the scanner.

- Specialized electrophysiological labs: In the groups of Prof. Klump, Prof. Weiler and Jun.Prof. Kretzberg several electrophysiological setups for performing auditory, retina and mechanosensory physiology are available.

- Animal psychophysics: AG Klump performs animal psychoacoustics in several acoustically treated measurement rooms. The animal navigation group disposes of a special wooden building equipped with experimental setups surrounded by magnetic coils to control the magnetic field in experiments with migratory birds.

- Animal care facility: A new “Tierhaus” has been granted to the Universität Oldenburg and will be completed in 2006. It will provide adequate and efficient facilities for the biology groups in Oldenburg to take care of those animals that are to be involved in the experiments.

- The new Oldenburg Flight Simulator (Mellert et al., 2005) is capable to create the virtual reality for both cabin and cockpit environment and can establish the environmental conditions for the investigation of long-haul flights (up to 12 hours). It is possible to change environmental conditions in the Flight Simulator - including motion - within a realistic range of parameters, except reduced pressure.

7.6 Laboratory facilities in Groningen The international graduate school overlaps with the neurosensory part of the graduate school for behavioural and cognitive neuroscience (BCN) in Groningen. This provides synergy effects both for the InterGK (i. e., utilize and perhaps further develop structures and experiences from BCN) and for BCN (i. e., increase contacts and mobility across


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national boarders as well as increase the spectrum of scientific expertise). The following special facilites are available in Groningen:

- Groningen Neuroimaging Centre: fMRI, PET-centre - Neurophysiological and biophysics labs - Biological centre Haaren: Circadian rhythm research isolation station - Computer graphics and visualization centre - Clinical and Neuroscience Research Facilities at the Dept. of Otorhinolaryngology

(Audiology), UMCG. These include: o Animal research laboratory for electrophysiology and histology o Testing facilities for human psychoacoustic including an anechoic

chamber

7.7 Additional support by the University of Oldenburg The University of Oldenburg supports the International Graduate School “Neurosensory Science, Systems and Applications” with several measures, including:

- Additional means for investments (116,000 Euro in the previous granting period including funds from the MWK) and coordination means (one quarter administrative assistant, one lab assistant for 18 hours/month)

- Also, the InterGK was given highest priority to take advantage out of the stipends from the “Graduiertenförderungsgesetz” of the State of Lower Saxony (one additional stipend granted to S. Emiroglu).

- Since most of the research groups have other third-party-funded projects, most of the graduates have no problems to obtain another position within the respective research group to finish their PhD project after the end of their stipend.

- The University of Oldenburg has been awarded the certificate “Familiengerechte Hochschule” by an auditing team due to several measures for increasing the attractiveness of the University of Oldenburg for students with children.

- Support for foreign students is organized by the International Students Office which organizes special events and helps the international students on practical terms. However, most of the international students within the InterGK are closely connected to their respective research groups so that the aid by the International Students Office is not required by these advanced students.

- Teaching load (Lehrdeputat): Currently, the study programme of the University of Oldenburg is completely renewed due to the complete introduction of Bachelor/Master study structures. Within these structures it is foreseen to have some additional teaching capacity for post-graduate education. However, at the moment only a teaching load of two SWS have been granted to the InterGK for the total of all professors. This is effectively used to supervise the common seminar of the InterGK. It is the explicit goal of the University of Oldenburg to support graduate schools with an adequate teaching capacity from the contributing professors.

8 Concluding remarks / Zwischenbilanz The International Graduate School “Neurosensory Science, Systems and Applications” has – at least in the opinion of the applicants – achieved its goal to become an international-oriented, interdisciplinary and high-quality-oriented research platform for PhD students in the area of neurobiology, applied physics, theoretical physics and communication engineering, psychology, and computer science. Due to the generous support from the State of Lower Saxony and the University of Oldenburg, it was possible to add several new, dynamic groups (mostly headed by young researchers) to the staff of the InterGK in Oldenburg. Similarly, the staff from Groningen could be significantly strengthened by adding new, active research professors and their respective graduate


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students. This – together with the active and enthusiastic participation of the funded and associated graduates – constitutes the dynamic spirit of the InterGK which makes it to one of the prominent activities of the contributing Universities of Oldenburg and Groningen. Special highlights of these activities are the summer schools organized by the InterGK, the international conferences connected to the InterGK, and the fact that all ex-graduates of the InterGK have had until now no problems in finding an adequate job when leaving the university. However, the broad scope of the InterGK and the international nature requires more activity than a usual research programme due to the usual friction across disciplines and across nationalities. In addition, it seems to be nearly impossible to fulfil all requirements put on the graduates of the InterGK simultaneously, such as, e.g.: research stay of several months abroad, participation in all extra courses and activities of the InterGK, excellent outcome of the dissertation with at least three internationally peer-reviewed papers as well as a duration of the dissertation project of less than three years. Also, it is quite difficult to find the appropriate candidates for stipends who take the challenge of trying to fulfil all these requirements at a payment rate that is below the standard BAT IIa/2 rate for “regular” third-party-sponsored research projects. Hence, the InterGK “Neurosensory Science, Systems and Applications” has tried to make the best out of these requirements and has tried to support the graduates as much as possible without putting too much pressure on them with regard to stay abroad and duration of the dissertation projects. Even though these negative points outlined above exist, the applicants as well as the graduates feel that the general outcome of the InterGK is definitely worth the extra effort. Hence, the hope is expressed that the reviewers find the work of the InterGK documented so far to be as positive as the members of the InterGK perceive it and that the basis for a successful prolongation period is provided by this.

InterGK 591: Short Reports of the Graduates Reporting Period 7/2002-6/2005

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International Graduate School (InterGK) 591 “Neurosensory science, systems and applications”

Appendix I: Short Reports of the Graduates (Reporting Period 7/2002-6/2005)

Dr. Annika Åkerfelt, Carl von Ossietzky Universität Oldenburg ................................................3 Drs. Meltem Ballan, Rijksuniversiteit Groningen .......................................................................5 Drs. Ronald van den Berg, Rijksuniversiteit Groningen ............................................................7 Dipl.-Phys. Rainer Beutelmann, Carl von Ossietzky Universität Oldenburg .............................9 Lic. Psychol. (Joyce) C.C. Boucard, Rijksuniversiteit Groningen............................................13 Dipl.-Phys. M. Sc. Michael Buschermöhle, Carl von Ossietzky Universität Oldenburg..........16 Dipl.-Phys. Sandra Buss, Carl von Ossietzky Universität Oldenburg .....................................19 Drs. ir. Michael ten Caat, Rijksuniversiteit Groningen .............................................................22 Dr. Ulrike Dicke, Carl von Ossietzky Universität Oldenburg....................................................24 Dr. Theo Dinklo, Rijksuniversiteit Groningen...........................................................................26 Dipl.-Geophys. Suzan Emiroglu, Carl von Ossietzky Universität Oldenburg ..........................28 Drs. Just J. van Es, Rijksuniversiteit Groningen......................................................................31 Dr. Stephan Ewert, Carl von Ossietzky Universität Oldenburg ...............................................34 Dipl.-Phys. Sandra Fobel, Carl von Ossietzky Universität Oldenburg ....................................38 LA Biol. Martin Greschner, Carl von Ossietzky Universität Oldenburg ...................................41 Aave Hannus, MsC, Rijksuniversiteit Groningen.....................................................................44 Dipl.-Phys. Stephan Heise, Carl von Ossietzky Universität Oldenburg ..................................47 Dr. Dirk Junius, Carl von Ossietzky Universität Oldenburg .....................................................49 Dr. Michael Kleinschmidt, Carl von Ossietzky Universität Oldenburg.....................................52 Dipl.-Biol. Karin B. Klink, Carl von Ossietzky Universität Oldenburg ......................................54 Dipl.-Phys. Kai Krajsek, Carl von Ossietzky Universität Oldenburg........................................57 Ir. Cris Lanting, Rijksuniversiteit Groningen.............................................................................58 Dipl.-Biol. Julia Maier, Carl von Ossietzky Universität Oldenburg...........................................60 Dipl.-Phys. Ronny Meyer, Carl von Ossietzky Universität Oldenburg ....................................63 Dipl.-Phys. Marc Nitschmann, Carl von Ossietzky Universität Oldenburg..............................64 Dr. Johannes Nix, Carl von Ossietzky Universität Oldenburg .................................................66 Dipl.-Phys. Handy Oey, Carl von Ossietzky Universität Oldenburg ........................................69 Carlos Rizzo, Rijksuniversiteit Groningen................................................................................71 M. Sc. Bodhisatya Sarker, Carl von Ossietzky Universität Oldenburg....................................72 Ir. Rick L. M. Schoffelen, Rijksuniversiteit Groningen..............................................................73 Dr. Timm Schubert, Carl von Ossietzky Universität Oldenburg ..............................................75 Dr. Frank Schütte, Neurobiologie, Carl von Ossietzky Universität Oldenburg........................78 Dipl.-Inform. Arne Schulz, Carl von Ossietzky Universität Oldenburg ....................................80 Dr. Mailin Segger-Junius, Carl von Ossietzky Universität Oldenburg .....................................81 Jennifer Shelley, M.S., Carl von Ossietzky Universität Oldenburg .........................................82 Lavina M. Slabu, Rijksuniversiteit Groningen ..........................................................................85 Dipl.-Psych. Rike Steenken, Carl von Ossietzky Universität Oldenburg.................................86 Dr. Claudia Steinbrink, Carl von Ossietzky Universität Oldenburg .........................................89 Dipl-Math MSc Stefan Strahl, Carl von Ossietzky Universität Oldenburg...............................92 Sonja Tomaskovic, Rijksuniversiteit Groningen ......................................................................95 Lic. Psychol. Ignacio Vallines, Carl von Ossietzky Universität Oldenburg..............................96 Dipl.-Psych. Riklef Weerda, Carl von Ossietzky Universität Oldenburg .................................99 Dr. ir. Alle Meije Wink, Rijksuniversiteit Groningen ...............................................................105 Dr. Huan Zhou, Carl von Ossietzky Universität Oldenburg ...................................................107 Dipl.-Biol. Melanie Zokoll, Carl von Ossietzky Universität Oldenburg...................................109


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REPORT OF POSTDOCTORAL FELLOWS.........................................................................112 Dr Annika Åkerfelt, Carl von Ossietzky Universität Oldenburg .............................................112 Dr. Jörn Anemüller, Carl von Ossietzky Universität Oldenburg ............................................113 Dr. Petra Arndt, Carl von Ossietzky Universität Oldenburg...................................................115 Dr. Mark Allen Bee, Carl von Ossietzky Universität Oldenburg ............................................120 Dr. ir. Gerke Hoiting, Carl von Ossietzky Universität Oldenburg...........................................123 Dr. rer. nat. Manfred Mauermann, Carl von Ossietzky Universität Oldenburg .....................124 Dr. Mark Pottek, Neurobiology, University of Oldenburg.......................................................127 Dr. Huan Zhou, Carl von Ossietzky Universität Oldenburg ...................................................130 REPORT OF QUALIFICATION STIPENDIATE.....................................................................131 Prashanth D’Souza, M.Eng., Universität Oldenburg .............................................................131


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Dr. Annika Åkerfelt, Carl von Ossietzky Universität Oldenburg

Visual-Tactile Stop Signal Inhibition

Thesis supervisors: Hans Colonius, Abteilung Kognitionsforschung, Carl v. Ossietzky Universität Oldenburg, Adele Diederich, IU Bremen

Summary This study investigated voluntary inhibition of programmed movements upon infrequent presentation of visual or tactile stop signals. Participants were to perform fast saccadic or manual responses to a visual or tactile target, but to cancel the response on the 25% of trials in which a stop signal of the other sensory modality was additionally presented. Reaction times were measured in each of the three experiments reported. Additionally, in two of these amplitudes of saccadic movements were collected, and event-related potentials on inhibition of manual responses were recorded in the third. The data was compared with predictions made by the race model proposed by Logan & Cowan (1984).

Tactile stimuli were successfully utilized both as go and as stop signals. Participants’ inhibition success was related to the delay of stop signal presentation. About half of the participants resorted to strategic responding in a subconscious attempt to increase stopping success. In each experiment, the reaction times of some participants showed small violations of the race model assumptions. The saccadic amplitude data from the failed inhibition trials exhibited strongly hypometric eye movements relative to responses on go trials, and the size of this effect increased with the duration of concurrent processing of the go and stop signals. This influence of the stop processing on the go response was interpreted as a contradiction to the context-independent processing supposed by the race model. No conclusive evidence was obtained on the effects of varying the spatial position of the stop signal in the horizontal plane.

Stop signal equivalents of the no-go enhancements were found in the eventrelated potentials. Their latencies and amplitudes differed greatly between successful and failed inhibition trials, but not across conditions with different stop signal timing. The effects were assumed to be a reflection of a prior decision to inhibit, rather than the manifestation of this decision.

Thesis period: September 2000 - August 2003, Thesis defence: July 2004

Publications and lectures: Invited speaker at colloquium of BioCog (Leipzig, Germany), January 2001, title of talk "Using Tactile

Stop Signals in Countermanding Experiments"

Publications in preparation: Åkerfelt, A., Colonius, H., Diederich, A. (submitted). "Visual-tactile saccadic inhibition", Experimental

Brain Research Åkerfelt, A., Sams, M., Jääskeläinen, I., Klucharev, V. (in preparation) "Evoked responses to visual-

tactile stop signal inhibition"

Cooperation with and/or relation to other projects: Binaural hearing (R.Beutelmann), EEG recordings (D.Junius)


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Participation in the study program (attended lectures, courses and conferences):

Conferences Oral Presentations 8/2003 12th European Conference on Eye Movements (Dundee, UK)

Posters 6/2004 5th Annual Meeting of the International Multisensory Research Forum

(Barcelona, Spain) 8/2003 34th European Mathematical Psychology Group Meeting (Madrid, Spain) 1/2003 Second Finnish Symposium for Eye-Movement Research (Helsinki, Finland) 8/2002 34th European Mathematical Psychology Group Meeting (Bremen, Germany) 12/2001 The 13th BOMG Annual Meeting (London, UK)

Other Activities 6/2004 International Graduate College visit to Tübingen 9/2003 BCN & BCN & Inter-GK Summer School on parallels in visual and auditory

processing (Oodorn, the Netherlands) 5/2003 International Graduate College visit to Copenhagen 3/2003 Erasmus Seminar on Mathematical Psychology (Debrecen, Hungary) 9/2002 – 3/2003 Visiting researcher at the Laboratory of Computational Engineering,

Helsinki University of Technology (Espoo, Finland) 1/2002 Erasmus Seminar on Mathematical Psychology (Stade, Germany) 9/2001 Helsinki Summer School in Cognitive Neuroscience (Lammi, Finland) 8/2001 EGK Summer School on the central auditory system (Bad Zwischenahn,

Germany) 3/2001 NeuroNord course on Neural Modelling (Bremen, Germany) 1/2001 Erasmus Seminar on Mathematical Psychology (Leuven, Belgium) 2000 – 2004 Various visits, events and lectures in Oldenburg and Groningen (the

Netherlands)

Teaching/supervision/ counseling within the graduate school: Student representative, SS 2003

List of stays abroad: 09/02 - 03/03 Laboratory of Computational Engineering, Helsinki University of

Technology, Espoo, Finland Regular meetings with the Groningen members of the international graduate school

Age when entering the graduate school: 22

Occupation after leaving the graduate school: Science Editor, GreenFacts asbl/vzw, Brussels, Belgium Public Relations Manager, GreenFacts asbl/vzw, Brussels, Belgium


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Drs. Meltem Ballan, Rijksuniversiteit Groningen


Thesis supervisors: Prof. dr. Jos B.T.M Roerdink, Institute for Mathematics and Computing Science, University of Groningen, Dr. M.M. Lorist, Experimental and Work Psychology, University of Groningen Dr. ir. Natasha M. Maurits, Department of Neurology, University Medical Center Groningen

Summary Different methods are available to study different aspects of human information processing. On the behavioural level, cognitive processes can be quantified in terms of speed and accuracy of task performance. Overt task performance, however, reflects the end product of a chain of information processing activities, taking place both before and after the presentation of relevant information. Event-related brain potentials (ERPs) can be used to investigate the timing and organisation of specific cognitive processes, especially during those times that no overt behaviour can be registered (e.g., when humans plan and prepare for upcoming actions). Recording event-related activity provides excellent temporal resolution (tenths of milliseconds). However, this method provides poor spatial resolution for establishing structure-function mapping. Functional magnetic resonance imaging (fMRI) is perfectly suitable to provide information about where activity is occurring in the brain while it is performing cognitive tasks.

The simultaneous measurement of behaviour, ERP and fMRI, possible at the Neuroimaging Center of the Groningen University, seems an important step forward concerning the integration of both functional and structural knowledge about human information processing. However, elucidating the relations between specific cognitive functions and brain structures which are active during the execution of mental processes is complicated, and data collected using different measurement techniques sometimes show inconsistent results.

An alternative method to study cognitive processes and the related neuronal bases of behaviour is the additive-factor method (AFM; Sanders, 1983; Sternberg, 1969, 2001, 2003). The rationale underlying this method is that by systematically changing a task variable in a quantitative way, differential effects on function specific processes can be traced. Thus, using the AFM, the task and the processes involved are kept constant. The processes that are carried out, however, differ in quantitative respect. Because task variables are related to specific processes, the observed effects can be interpreted more precisely in terms of function or related structure. If manipulation of two task variables shows additive effects (i.e. if they do not interact) they are assumed to influence different processes. Because the AFM seems to have many advantages compared to the subtraction method we would like to be able to use this method within the setting of the Neuroimaging Center. To implement this method we first want to replicate part of the results of Pinel and colleagues (2001). They observed clear effects of numerical distance in specific brain areas. Moreover, we want to extend these findings by adding an additional task variable: degradation of the visual stimulus. Manipulations of a task variable (e.g., stimulus quality or numeral distance) are expected to affect specific functions and brain areas in a quantitative way.


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Thesis period: December 2004- December 2008

Publications and lectures: none so far

Publications in preparation: M. Ballan et al., An ERP Study on a Number Comparison Task.

Cooperation with and/or relation to other projects: Discussion in seminars and group meetings with the members of the Neuroimaging Center Groningen.

Participation in the study program (attended Lectures, courses and conferences): 10/2004: InterGK Meeting, Groningen (organised by JBTM Roerdink) 02/2005: InterGK Meeting, Groningen (organised by FW Cornelissen) Regular attendance at BCN (mini-) symposia Regular attendance at Computer Science colloquia (Groningen) Compulsory BCN courses (BCN Orientation course, BCN poster presentation, BCN

PhD retreat, BCN symposium, BCN master class, BCN lectures, Project Management, BCN Statistics, Publishing in English)



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Drs. Ronald van den Berg, Rijksuniversiteit Groningen

Feature perception in visualisation

Thesis supervisors: Prof. dr. Jos B.T.M Roerdink, Institute for Mathematics and Computing Science, University of Groningen, Dr. Frans W. Cornelissen, Lab Experimental Ophthalmology & BCN Neuro-imaging Center, University of Groningen

Summary Advances in science and technology resulted in the production of data sets that are huge and that still seem to be growing at an almost exponential rate. Information visualisation is a research area that aims at developing methods for effective communication of these data. Such methods can be viewed as transformations from sets of numbers into images that provide the user with the information s/he is looking for, e.g., patterns or oddities in the data or relationships between different data dimensions. Effective transformations seem trivial for small data sets of low dimensionality (e.g., xy-graphs for two-dimensional data), but pose a serious problem for data sets with many data points divided over multiple dimensions and often even over multiple layers. Typical examples of the latter are neuroimaging data and genetic networks.

Most of today's visualisation problems allow a nearly infinite number of data-to-image mappings, of which usually only a few appear to be effective. In the past decades, information visualisation (or 'perceptualisation') has received broad attention from both the industry and research community and one of the main research themes currently concerns the finding of general principles that distinguish effective mappings from non-effective ones.

Since it is the human brain that has to interpret the images, it is generally assumed that these general principles are to a large extent determined by how information processing in the human visual system works. As a result, information visualisation is more and more becoming an interdisciplinary and experimental research area. It combines knowledge and methodology from areas as broad as perception and cognition research, art, and computing science. Information visualisation practices that are driven by knowledge of human perception is often referred to as 'perceptual visualisation', 'information psychophysics', or 'perception-based visualisation'.

In my project, this relationship between visualisation and perception plays a central role. We strive after an approach in which novel visualisation methods are (i) inspired by knowledge of perception and (ii) formally evaluated on effectiveness. A subject directly related to the latter concerns the concept of quality metrics, i.e., objective measures (predictions) of the perceptual effectiveness of a given visualisation.

Thesis period: 1.6.2004-1.6.2008

Publications and lectures: Conference Abstracts: Van den Berg R, Hannus A, Roerdink JBTM, Cornelissen FW (2005). A colour-size processing

asymmetry in visual conjunction search. Poster presented at ECVP05, August 2005. Van den Berg R, Cornelissen FW, Hannus A, Roerdink JBTM (2005). Simultaneous colour search

renders other object features less salient. Poster presented at APGV05, August 2005.


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Publications in preparation: Van den Berg R, Cornelissen FW, Roerdink JBTM (2005). An assessment of feature interference and

hierarchy in visual search, in preparation


Participation in the study program (attended lectures, courses and conferences): 07/2004: International Conference on Information Visualization (IV04), London 10/2004: InterGK Meeting, Groningen, Netherlands (organised by JBTM Roerdink) 02/2005: InterGK Meeting, Groningen, Netherlands (organised by FW Cornelissen) 08/2005: ECVP 2005, A Coruna, Spain 08/2005: APGV 2005, A Coruna, Spain



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Dipl.-Phys. Rainer Beutelmann, Carl von Ossietzky Universität Oldenburg

Modelling the Influence of Room Acoustics on Speech Intelligibility in Noise for Hearing Impaired Subjects

Thesis supervisor: Prof. Dr. Dr. Birger Kollmeier, Medizinische Physik

Understanding speech is an everyday task, but is often made difficult by various interferences, such as all kinds of noise, other talkers, and reverberation. Adding to this, hearing impairment decreases intelligibility substantially.

Among the strategies employed by listeners in order to extract as much useful infor-mation as possible, binaural hearing is one of the most important ones. By using the spatial information encoded in the different delays and amplitudes of acoustic signals from different directions due to the distance between the ears and the head shadow-ing effect, speech and noise can be segregated and the interference can be sup-pressed.

A binaural model, capable of predicting speech intelligibility under the influence of noise, reverberation, and hearing loss, may help understanding the underlying mechanisms of binaural hearing and may assist in the development and fitting of hearing aids.

Model of binaural speech intelligibility The model, which is being investigated and enhanced in the course of this disserta-tion project, is based on an approach by vom Hövel (1984). It combines binaural equalization-cancellation (EC) processing (Durlach, 1963) with the monaural speech intelligibility index (SII; ANSI, 1997).

The model processes speech and noise signal waveforms, which have to be avail-able separately. Two uncorrelated internal masking noises accounting for the individ-ual hearing thresholds of the two ears are added to the noise signal prior to dividing the binaural input signals into frequency bands. Independent EC stages in each band with artificial errors, which simulate human inaccuracy, calculate residual monaural signals consisting of speech and noise, respectively, with the best possible signal-to-noise ratio in each frequency band. The artificial EC processing errors have been derived from binaural masking level difference data using pure tones. The signals are resynthesized into each a broadband speech and noise signal, and with the aid of the SII, a speech reception threshold (SRT) is computed.

Reverberation effects are treated implicitly in the binaural part of the model. The monaural disturbance of speech is so far neglected, but shall be incorporated by using the speech transmission index (STI; IEC, 1998), which is suitable for monaural reverberated speech. No model parameter has been fitted to SRT data.

Evaluation of the model First evaluations showed that such a straightforward functional model is able to pre-dict binaural speech intelligibility under realistic conditions such as spatial sound source configuration, reverberation and hearing loss (Beutelmann and Brand, 2005). Particular attention was paid to which kind of the listeners' individual parameters (such as the pure tone audiogram) were necessary for accurate predictions. Model


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predictions were compared to observed SRT values for various combinations of noise source azimuths, room acoustic conditions and hearing losses. As a com-promise between realistic situations and easy handling, measured manikin head related transfer functions including room impulse responses have been used.

So far, the model has been evaluated using speech intelligibility measurements with eight normal-hearing and 15 hearing-impaired listeners. SRT data have been col-lected for three different room acoustic conditions (anechoic, office room, cafeteria hall) and eight directions of a single noise source (speech in front). The overall cor-relation coefficient between predicted and observed SRT values was 0.92. The de-pendence of the SRT of an individual listener on the noise direction and on room acoustics was predicted with a mean correlation coefficient of 0.88. The effect of individual hearing impairment was predicted with a mean correlation coefficient of 0.93. However, for mild hearing losses the decrease of release from masking was underestimated.

Preliminary measurements and predictions with (simulated) hearing aids show, that the influence of (linear) hearing aids on binaural speech intelligibility can be predicted by the model described here.

State of the dissertation project The development and evaluation of the model described above represents about one third of the dissertation project. The main goal for this part was to include an individual hearing threshold into the model and to show that it can predict binaural SRT values for a broad range of hearing-impaired subjects.

The planned further work covers two main tasks. The first and more important is to investigate the limits of the model in respect to room acoustics and to expand it in order to overcome them. As mentioned earlier, this may require the use of monaural measures for the influence of reverberation on speech, for example the STI (IEC, 1998). For this purpose, measurements with far field speech and noise have already been prepared.

The second task is to carry on with measurements and predictions of the effect of hearing aids on binaural speech intelligibility. It is theoretically even possible to feed the signals of compressive hearing aids into the model, if the gain parameters and time constants are known. The ability of the model to predict SRT values for these kinds of signals will be examined.

Some work will also be done to improve the model on a rather technical level. The aim is on one hand to make the model calculations faster and more efficient and on the other hand to make it easier to exchange data with and to test hypotheses on rather psychoacoustical models.

References: ANSI (1997). „Methods for the Calculation of the Speech Intelligibility Index,“ American National

Standard S3.5-1997, Standards Secretariat, Acoustical Society of America. Durlach, N. I. (1963). „Equalization and Cancellation Theory of Binaural Masking-Level Differences,“ J.

Acoust. Soc. Am. 35(8), 1206-1218. IEC (1998) “Sound system equipment - Part 16: Objective rating of speech intelligibility by speech

transmission index,” International Standard IEC 60268-16 (1998). vom Hövel, H. (1984). „Zur Bedeutung der Übertragungseigenschaften des Außenohrs sowie des

binauralen Hörsystems bei gestörter Sprachübertragung,“ Dissertation, Fakultät für Elektrotechnik, RTWH Aachen.


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Thesis period: Oct 2003 – Jul 2005

Publications and Lectures:

Articles: Beutelmann R, Brand T, Kollmeier B (2003). „Sprachverständlichkeit in räumlichen

Störgeräuschsituationen“, Zeitschrift für Audiologie, Suppl. 6, in press Beutelmann R, Brand T, Kollmeier B (2004). „Sprachverständlichkeit in räumlichen

Störgeräuschsituationen“, Zeitschrift für Audiologie, Suppl. 7, on CD Beutelmann R, Brand T (2005). „Prediction of speech intelligibility in spatial noise and reverberation for

normal-hearing and hearing-impaired listeners”, J. Acoust. Soc. Am., submitted

Talks: Beutelmann R, Brand T, Kollmeier B (2003). „Sprachverständlichkeit in räumlichen

Störgeräuschsituationen“, 30. Erlanger Kolloquium audiologisch tätiger Physiker und Ingenieure, Erlangen, 6.2.2003

Beutelmann R, Brand T, Kollmeier B (2003). „Sprachverständlichkeit in räumlichen Störgeräuschsituationen“, 6. Jahrestagung der DGA, Würzburg, 26.3.2003

Beutelmann R, Brand T, Kollmeier B (2004). „Sprachverständlichkeit in räumlichen Störgeräuschsituationen – Teil 2: Schwerhörende“, 7. Jahrestagung der DGA, Leipzig, 11.3.2004

Beutelmann R, Brand T (2005). „Der Einfluss von Hörgeräten auf das binaurale Sprachverstehen – Messungen und Modellvorhersagen“, 8. Jahrestagung der DGA, Göttingen, 24.02.2005

Poster: Beutelmann R, Brand T (2004). „Modelling binaural speech intelligibility in rooms for normal-hearing

and hearing-impaired listeners”, Poster

Cooperation with and/or relation to other projects: Within the InterGK: Cooperation with studies related to psychcoacoustical binaural

modeling, particularly with Marc Nitschmann and Jesko Verhey Kompetenzzentrum HörTech, influence of hearing aids on speech intelligibility Integrated Project HearCom “Hearing in the Communication Society”, room acoustics

and speech intelligibility

Participation in the study program (attended lectures, courses and conferences): InterGK seminar, weekly during semester, Oldenburg, including regular presentation

of own work InterGK meetings, monthly, Groningen/Oldenburg 08/2002: “Binaural Hearing at Cocktail Parties”, HWK Delmenhorst, Germany 02/2003: 30. Erlanger Kolloquium audiologisch tätiger Physiker und Ingenieure,

Erlangen, Germany. (own talk) 03/2003: 6. Jahrestagung der Deutschen Gesellschaft für Audiologie, Würzburg,

Germany. (own talk) 06/2003: Workshop “Spatial and Binaural Hearing”, Utrecht, The Netherlands 03/2004: 7. Jahrestagung der Deutschen Gesellschaft für Audiologie, Leipzig,

Germany. (own talk) 06/2004: Symposium with the GK „Kognitive Neurobiologie“, Tübingen, Germany

(short presentation of own work) 08/2004: Summerschool „Object formation in audition and vision: Bottom-Up and

Top-Down processing“, Bad Zwischenahn, Germany. (poster presentation) 08/2004: Hanse Workshop in Hearing Research “Auditory scene analysis and speech

perception by human and machine”, HWK Delmenhorst, Germany. (poster presentation)


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02/2005: 8. Jahrestagung der Deutschen Gesellschaft für Audiologie, Göttingen, Germany. (own talk)

Teaching/supervision/counseling within the graduate school: Student project supervision “Binaurale Experimente und Modellierung” within the lab

course “Neurosensorik”, 27.09.2004 – 01.10.2004 Implementation of a semi-automatic mouse head orientation tracker tool in MATLAB

for Julia Maier

List of stays abroad: Regular meetings with the Groningen members of the international graduate school



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Lic. Psychol. (Joyce) C.C. Boucard, Rijksuniversiteit Groningen

fMRI of brightness induction in human visual cortex

Thesis supervisor: Frans W Cornelissen

One of the fundamental questions in visual science is whether the brightness of a surface, i.e. its perceived luminance, is explicitly represented in early visual cortical areas. In the powerful brightness induction illusion (where a grey surface on a bright background appears to be darker than the same surface on a dark background, fig.1), the perceptual experience of brightness is dissociated from the actual physical stimulation. It provides thus an elegant manner to study this issue.

We used fMRI to study the phenomenon. While being scanned, subjects viewed centre-surround displays in which either centre- or surround-luminance was modulated in time. In both cases, subjects perceive similar brightness changes in the central surface. In the region of visual cortex encoding this central surface, both modulations evoked comparable fMRI responses. However, the surround modulation signal showed a considerable delay relative to the onset of the brightness percept (fig.2).

We conclude that the human retinotopically organised visual cortex does not explicitly represent brightness. Yet, we did observe delayed fMRI signal suggesting that those areas might play a more indirect role in the perception of surface brightness. Finally, our results emphasize that in spatial fMRI tasks, it is important to consider the magnitude of activations as well as their temporal characteristics.

Fig. 1. Brightness induction. A grey surface on a bright background appears to be darker than the same surface on a dark background.

Fig. 2. Time-course of the fMRI signal in the foveal ROI for both centre and surround modulations and in the peripheral ROI for the surround modulation. Note the delay of at least 3 s for the signal onset in the foveal ROI during surround modulation relative to the other two conditions.


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Thesis period: 01.01.2002 – 30.04.2006, State of the Dissertation Project: expected dissertation end april 2006., University of Groningen (NL)

Publications and lectures: Boucard CC, Mostert JP, Cornelissen FW, De Keyser J, Oudkerk M, Sijens PE. Visual Stimulation, 1H

MR Spectroscopy and fMRI of the Human Visual Pathways. Eur Radiol. 2005 Jan;15(1):47-52. Boucard CC, van Es JJ, Maguire RP, Cornelissen FW. Functional Magnetic Resonance Imaging of

Brightness Induction in the Human Visual Cortex. Neuroreport. 2005 Aug 22;16(12):1335-8. Boucard CC, Maguire RP, Roerdink JBTM, Jansonius NM, Hooymans JMM, Cornelissen FW. Neuro-

Imaging of Changes in Occipital Cortical Structure Related with Retinal Visual Field Defects. In preparation

Cooperation with and/or relation to other projects: This dissertation project has a relationship concerning the studied questions as well as the employed methods to the projects of Prof. Dr. Greenlee (Oldenburg, projects of R. Weerda & I. Vallines). Parts of the project “fMRI of brightness induction” were carried out in collaboration with Prof. Mark W. Greenlee (Oldenburg; student project of Jeroen Benjamins).

Participation in the study program (attended Lectures, courses and conferences):

Courses 28/02-04/04: BCN orientation course, RUG, Groningen (NL) 02-08/04/2002: BCN fMRI course, RUG, Groningen (NL) 17-18/04/2002: BCN PhD retreat, Doorwerth (NL) 16-21/05/2002: SPM course, London (UK) 23-28/6/2002: Tool-kit Neuroscience course, Nijmegen (NL) 04/09 – 20/11/2002: Presentation in english course, RUG, Groningen (NL) 21-22/11/2002: Project Management course, RUG, Groningen (NL) 02/12/2002-21/03/2003: Head & neck and brain anatomy course, RUG, Groningen

(NL) 16/04/2003: BCN retreat, Doorwerth (NL) 21/06/2004-09/07/2004: writing in English course, RUG, Groningen (NL) 20/09 – 26/09/2004: Brain and Mind IV, Dubrobnik (HR) 14/04/2005: BCN retreat, Odoorn (NL)

Conferences 04/12/2002: NeuroNord conference, Cognitive and Emotional Neuroscience;

Delmenhorst, Germany. (talk: fMRI of cortical brightness induction in early human visual cortex)

25/01/2003: OOG; Paterswolde, The Netherlands. (talk: Neuro-imaging of cortical reorganisation and degeneration following visual field defects and fMRI of cortical brightness induction in early human visual cortex)

30/01/2003: Poster day BCN; Groningen, The Netherlands. (poster: fMRI of cortical brightness induction in early human visual cortex)

10/02/2003: Fac. Psychology UB; Barcelona, Spain. (talk: Neuro-imaging of cortical reorganisation and degeneration following visual field defects and fMRI of cortical brightness induction in early human visual cortex)

16/04/2003: BCN retreat 2003; Doorwerth, The Netherlands. (talk: fMRI of cortical brightness induction in early human visual cortex)


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22/05/2003: EuroGK mini-symposium; Copenhagen, Denmark. (poster: fMRI of cortical brightness induction in early human visual cortex)

10-15/07/2003: IBRO 2003; Praha, Czech Republic. (poster: fMRI of cortical brightness induction in early human visual cortex)

01-05/09/2003: ECVP 2003; Paris, France. (talk: fMRI of cortical brightness induction in early human visual cortex)

19/09/2003: BCN mini-symposium fMRI course; Groningen, The Netherlands. (talk: fMRI of cortical brightness induction in early human visual cortex and problematic issues)

29/01/2004: poster day BCN; Groningen, The Netherlands. (poster: Visual Stimulation, 1H MR Spectroscopy and fMRI of the Human Visual Pathways)

17/04/2004: public day BCN - NeuroImaging Centre; Groningen, The Netherlands. (poster: Neuro-imaging of cortical reorganisation and degeneration following visual field defects)

20-26/09/2004: Mind & Brain IV, Images of the working brain; Dubrovnik, Croatia. (talk: Neuro-imaging of cortical reorganisation and degeneration following visual field defects)

List of stays abroad: August 2005: Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (USA)


Occupation after leaving the graduate school (if applicable): Post-doc at RIKEN (JAP)


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Dipl.-Phys. M. Sc. Michael Buschermöhle, Carl von Ossietzky Universität Oldenburg

Neurosensory Modeling of Signal Detection in Comodulated Stimuli

Thesis supervisors: Prof. Dr. Ulrike Feudel, Theoretical Physics/ Complex Systems, Dr. Jan Freund, Theoretical Physics/ Complex Systems

In a wide range of natural auditory environments, the structure of typical sounds can be described as comodulated, which refers to common amplitude modulations across different frequency regions. These sounds often act as noise impairing the detection of signals. It has been shown that signal detection in the presence of comodulated noise may be improved compared to uncorrelated noise conditions (Verhey et al., 2003). Understanding and modeling the neurosensory mechanisms leading to these kinds of effects is the main goal of the dissertation project.

One well known example for improved signal detection in comodulated noise is the comodulation detection difference (CDD, McFadden 1987), which denotes a differing detection threshold for narrowband noise in the presence of masking noise bands that are either coherently modulated with the signal band or modulated in a differing fashion. In cooperation with the zoophysiology and behaviour group (G. Klump, M. Bee), neuronal response data to CDD stimuli was collected and analyzed for possible neural codes leading to CDD. After originally applying spike sorting algorithms and making use of symbolic dynamics to quantify the neural responses to these stimuli, we came to the conclusion that a satisfying explanation for CDD may already be found in the time and population averaged firing rates of the recorded neurons encoding the compressed envelope of the filtered stimulus. In agreement with previous publications (e.g. B. Moore and S. Borrill, 2002), we proposed a within-channel explanation for CDD that incorporates a simple and convincing model reproducing the neuronal response data with good numerical agreement (cf. Fig. 1) while depending on very few parameters that may be determined independently of the CDD experiments (Buschermöhle et al., 2005).

Further analysis of the model and application to the varying recording sites is currently done in order to determine the exact extent to which CDD can be explained by the model (paper in preparation). Additionally, a comparison with the starling’s behavioral CDD results is possible (U. Langemann et al, 2005). As soon as the model has been adequately described, predictions about neural responses to novel stimuli will be possible that may be validated by experiments.

A second paper that is currently in preparation is a survey of the literature on CDD and related effects in order to compare human psychophysical data with our model


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predictions. Preliminary results are very promising but need further consolidation before publication.

Future research will focus on two main points: Firstly, our analysis of comodulated noise hints at possible usage for stochastic resonance (SR). To our knowledge, comodulated noise has not yet been examined with respect to SR despite its wide spread appearance in nature. For investigating SR with comodulated noise, collaboration with J. Verhey is planned in order to perform psychophysical experiments alongside the theoretical work. Secondly, we plan an extension of the within-channel model to allow for multi-channel processing such that psychophysical phenomena that are assumed to be due to across-channel processes can as well be modeled.

Only one year after its start, the dissertation project has made considerable progress and already produced interesting results. The two papers currently in preparation will prospectively be ready for submission within the next six months, such that there will be a good chance of finishing the planned future research within the projected duration of the dissertation project.

References: J.L. Verhey, D. Pressnitzer, and I.M. Winter, Exp. Brain Res. 153, 405 (2003). D. McFadden, J. Acoust. Soc. Am. 81, 1519 (1987). B.C.J. Moore and S.J. Borrill, J. Acoust. Soc. Am. 112, 2099 (2002). M. Buschermöhle, U. Feudel, M.A. Bee, G.M. Klump, and J.A. Freund, submitted to Phys. Rev. Lett. (2005) U. Langemann, M.A. Bee, and G.M. Klump, in ARO 28th Annual Midwinter Research Meeting (2005).

Thesis period: 06/2004-05/2007 (projected), scholarship period: 06/2004-05/2006


Publications: Buschermöhle M., Feudel U., Bee M.A., Klump G.M., and Freund J.A. (2005) “Signal Detection

Enhanced by Comodulated Noise”, submitted to Physical Review Letters Buschermöhle M., Whittet D.C.B., Chrysostomou A., Hough J.H., Lucas P.W., Adamson A.J., Whitney

B.A., and Wolff M.J. (2005) “An Extended Search for Circularly Polarized Infrared Radiation from the OMC-1 region of Orion”, Astrophysical Journal 624, 821-826

Lectures/ Talks: ”Modeling CDD: Detection of Signals in Comodulated Noise“, talk held on June 8, 2005 at the

Theoretical Neuroscience Lab of the Institute for Theoretical Biology at the Humboldt University Berlin

”Signal Detection in Comodulated Noise: A Simple Model of the CDD-Effect“, talk held on June 7, 2005 at the seminar of the Statistical Physics and Nonlinear Dynamics group at the Humboldt University Berlin

“A Review of Spike Sorting: Methods and Applications”, talk held on May 20, 2005 at the Seminar of the International Graduate School for Neurosensory Science and Systems at the Carl-von-Ossietzky University Oldenburg

”Signal Detection in Comodulated Noise: A Simple Model of the CDD-Effect“, talk held on March 23, 2005 at the meeting with members from the Graduiertenkolleg Kognitive Neurobiologie (Eberhard-Karls University Tübingen) at the Carl-von-Ossietzky Unive rsity Oldenburg

“Neuronal Mechanisms of Detection and Segregation of Modulated Auditory Signals”, talk held on December 10, 2004 at the Seminar of the International Graduate School for Neurosensory Science and Systems at the Carl-von-Ossietzky University Oldenburg

Publications in preparation: Bee M.A., Buschermöhle M., Feudel U., Freund J.A., and Klump G.M. (in preparation) “Comodulation

detection differences in starlings: II. Neural mechanisms for segregating modulated signals from modulated noise”, to be submitted to European Journal of Neuroscience


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Buschermöhle M., (in preparation) “Peripheral Within-Channel Processes Accounting for Comodulation Detection Differences”, to be submitted to Journal of the Acoustical Society of America

Cooperation with and/or relation to other projects:

This dissertation project is carried out in close collaboration with the zoophysiology and behaviour group (M. Bee, G. Klump, U. Langemann). Fruitful discussions have been going on with the neurosensory science group (J. Verhey, S. Ernst). Future psychoacoustical measurements parallel to theoretical SR work are planned with the Neurosensory Science Group (J. Verhey, S. Ernst, S. Heise).


Lectures: Psychological, physiological, and audiological acoustics, Lecture, 2004, Oldenburg Physiology of the auditory system, Lecture, 2004, Oldenburg Stochastic processes and their applications in modeling, Lecture, 2005, Oldenburg Regular attendance at the seminar of the international graduate school for

neurosensory science and systems. Regular attendance at the physical colloquium. Regular attendance at the seminar theoretical physics/ complex systems.

Courses: 06/2005: Workshop on Moderation of Discussions 09/2004: “Practical: psychophysics, neurosensory sciences, and auditory signal

processing“, Oldenburg, Germany

Conferences: 05/2005: Mini-Symposium: Cochlea Modeling, Oldenburg, Germany (attended) 08/2004: Summer school of the international graduate school for neurosensory

science and systems (object formation in audition and vision: bottom-up and top-down processing), Bad Zwischenahn, Germany (poster contribution)

Teaching/supervision/counseling within the graduate school: Organization of one of the monthly meetings of the international graduate school:

Neurosensory Information Processing: Phenomena and Models (07/2005)

List of stays abroad: Regular meetings with the Groningen members of the international graduate school



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Dipl.-Phys. Sandra Buss, Carl von Ossietzky Universität Oldenburg

Temporal and spectral analysis of acoustical signals by calculating contours

Thesis supervisor: Prof. Dr. Volker Mellert, Arbeitsgruppe Akustik, Institut für Physik

Introduction In order to improve tyres, subjective evaluations of tyre/road noise are carried out. In search of a correlation between subjective assessments and objective signal parameters, tyre/road noises with systematic variations of their spectra are evaluated concerning the pattern noise strength. Thereby it is focussed on pattern noise, a tonal component of the tyre/road noise generated by the tread pattern hitting the road surface due to a disadvantageous pattern geometry. Objective parameters are calculated from the order spectra and correlated with the subjective evaluation of pattern noise.

The method of calculating contours was developed in order to find tonal components in noise. Here the calculation of contours is used to find tonal components in tyre/road noise. Parameters calculated from the contours are also correlated with the evaluation of pattern noise.

Objective signal parameters correlated with pattern noise It is known that pattern noise is related to the first pitch harmonics (around the 60th order of the tyre revolutions). A subjective test is carried out in order to find signal parameters correlated with pattern noise. From previous tests it is known that the pattern noise strength is related to the level and the spectral shape of the first pitch harmonics. An increasing level or an increasing tonality of the first pitch harmonics lead to an increasing pattern noise strength.

In a paired comparison test tyre/road noises with systematically varied level and spectral shape of the first pitch harmonics are evaluated concerning the pattern noise strength. The results of the former experiments are reproduced: when leaving the spectral shape of the first pitch harmonics constant, an increasing level of the first pitch harmonics leads to an increasing pattern noise strength. Also an increasing pattern noise strength with increasing tonality of the first pitch harmonics is found when leaving the level of the first pitch harmonics constant. But overall both parameters are not able to sufficiently measure the perceived pattern noise strength. The parameter showing the highest correlation with the pattern noise evaluation is the difference between the level of the first pitch harmonics and the level of the low order range.

Calculating contours In the next step contours are calculated from the tyre/road noises. The calculation of contours is based on the procedure developed by Mummert (Mummert, M. (1998). Sprachkodierung durch Konturierung eines gehörangepaßten Spektrogramms und ihre Anwendung zur Datenreduktion. Dissertation, München, VDI-Fortschrittberichte, Reihe 10, VDI-Verlag, Düsseldorf). Contour points are maxima of the level at certain points in time in the spectrogram. Contour points at successive points in time and close together in level and frequency are combined to lines. Long lines, the contours, represent perceivable tones in the signal. Therefore, the calculation of contours is an aurally adequate signal analysis. From the contours an order spectrum is calculated.


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The level of the first pitch harmonics of the contours is a parameter related to the level and the tonality of the first pitch harmonics. It is a measure for the level of the tonal components of the first pitch harmonics. This parameter is highly correlated with the evaluated pattern noise strength. Also applied to the previous experiments concerning a variation of the level or the spectral shape of the first pitch harmonics, the level of the first pitch harmonics of the contours is a good measure for the perceived pattern noise strength. The correlation between the level of the first pitch harmonics and the pattern noise evaluation is much increased when calculating this parameter from the contours instead of the unprocessed order spectrum.

Conclusion In order to find an objective parameter related to the subjective rating of pattern noise, it’s strength is evaluated in subjective tests. An increasing level of the first pitch harmonic or an increasing tonality of the first pitch harmonics lead to an increasing pattern noise strength. But if both parameters are varied together, both parameters alone do not measure the perceived pattern noise strength.

An aurally adequate signal analysis, the calculation of contours, is applied to the signals. Contours correspond to perceivable tonal components of the signal. The level of the first pitch harmonics of the contours is a parameter related to the level and the tonality of the first pitch harmonics. It correlates best with the evaluated pattern noise strength even if the level as well as the spectral shape of the first pitch harmonics are varied.

Thesis period: 10/1999 – 2005 (expected)

Publications and Lectures: Buss, S., Weber, R., and Liederer, W. (2002). Objektivierung des subjektiv wahrgenommenen

Profilgeräuschs in Reifen-Fahrbahn-Geräuschen. DAGA 2002, Bochum, Germany. DEGA e.V., Oldenburg.

Buss, S., Weber, R., and Liederer, W. (2003). Wahrnehumg des Profilgeräuschs in Reifen-Fahrbahn-Geräuschen. DAGA 2003, Aachen, Germany. DEGA e.V., Oldenburg.

Baumann, I., Bellmann, M., Buss, S., Faulhaber, P., Freese, N., Groll-Knapp, E., Hallmann, S., König, C., Kruse, R., Leitmann, T., Mellert, V., Remmers, H., Röder, A., Schulte-Fortkamp, B., Trimmel, M., and Weber, R. (2003). HEACE: Simulation von Schall, Vibrationen und anderer Umgebungsvariablen im Kabinensimulator. DAGA 2003, Aachen, Germany. DEGA e.V., Oldenburg.

Baumann, I., Bellmann, M., Buss, S., Freese, N., Groll-Knapp, E., Hallmann, S., König, C., Kruse, R., Leitmann, T., Mellert, V., Remmers, H., Schulte-Fortkamp, B., Trimmel, M., and Weber, R. (2003). HEACE: Versuchsdesign zur Erfassung der Belastung, der Beanspruchung und des Komforts von Passagieren und der Crew in einem Kabinensimulator. DAGA 2003, Aachen, Germany. DEGA e.V., Oldenburg.

Baumann, I., Bellmann, M., Buss, S., Freese, N., Groll-Knapp, E., Hallmann, S., König, C., Kruse, R., Leitmann, T., Meixner-Pendleton, M., Mellert, V., Remmers, H., Schöls, M., Schulte-Fortkamp, B., Trimmel, M., and Weber, R. (2003). The assessment of load, strain and comfort of flight crew and cabin crew in a cabin simulator – test design. Euronoise 2003, Naples, Italy.

Buss, S., and Weber, R. (2004). Subjective and objective characterisation of tonal components in tyre/road noise. CFA/DAGA ’04, Strassbourg, France.

Weber, R., Baumann, I., Freese, N., Buss, S., König, C., and Mellert, V. (2004). Effects of noise on the comfort of cabin crew studied in an aircraft cabin simulator. ICA 2004, Kyoto, Japan.

Buss, S., and Weber, R. (2004). Perception of Tonalness of Tyre/Road Noise and Objective Correlates. Internoise 2004, Prague, Czech Republic.

Buss, S., Kruse, R., and Weber, R. (2005). Einfluss des Schalls und anderer Umgebungsvariablen auf das Komfortempfinden in der Flugzeugkabine. DAGA 2005, München, Germany. DEGA e.V., Oldenburg.


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Publications in preparation: Buss, S., and Weber, R. (2005). Subjektive Wahrnehmung des Profilgeräuschs, eines tonalen Anteils

des Reifen/Fahrbahn-Geräuschs, und seine objektive Charakterisierung. In preparation for “Subjektive Fahreindrücke sichtbar machen III”, Essen, Germany, December 8-9, 2005, to be published by Expert Verlag, Renningen, Germany.

Cooperation with and/or relation to other projects: The work was carried out in cooperation with the tyre manufacturer Continental AG, Hannover, Germany in the project “Prädiktion von subjektiven akus tischen Qualitätsurteilen über Reifen/Fahrbahngeräusche auf der Basis von gemessenen akustischen und Psychoakustischen Signalparametern (prediction of subjective assessment of quality metrics for tyre-/roadsurface noise on basis of measured acoustic and psychoacoustic parameters”.

Close cooperation was carried out in the InterGK with projects related to psychoacoustics, in particular with S. Ewert (modeling), S. Emirogly (object recognition), M. Nitschmann (inattentive observer) and S. Heise (modulation perception).

Participation in the study program (attended lectures, courses and conferences): 3/2002: DAGA 2002, Bochum, Germany 3/2002: Aircraft interiors Expo 2002, Hamburg, Germany 2/2003: Aircraft interiors Expo 2003, Hamburg, Germany 3/2003: DAGA 2003, Aachen, Germany 3/ 2004: CFA/DAGA 2004, Strasbourg, Germany 8/2004: Summerschool of the International Graduate School Neurosensory Science

and Systems “Object formation in audition and vision: Bottom-up and top-down processing”, Bad Zwischenahn, Germany

8/2004: Inter-noise 2004, Prague, Czech Republic 2/2005: DAGA 2005, Munich, Germany Weekly Seminar of the International Graduate School Neurosensory Science and

Systems, 2002-2005, Oldenburg

Teaching/supervision/ counseling within the graduate school: Supervision of lab course “Psychoacoustics”, 10/2003-2/2004, Oldenburg

List of stays abroad: Regular meetings with the Groningen members of the international graduate school Conferences CFA/DAGA 2004, Strasbourg, France, and Inter-noise 2004, Prague,

Czech Republic.



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Drs. ir. Michael ten Caat, Rijksuniversiteit Groningen

Interactive Visualization Techniques for the Interpretation of Functional Neuroimaging Data

Thesis supervisors: Prof. dr. Jos B.T.M Roerdink, University of Groningen, Dr. ir. Natasha M. Maurits, Department of Neurology, University Medical Center Groningen

Summary In many different fields, people have to deal with data containing more information than they can easily comprehend. To support the interpretation of the data in those fields, Scientific Visualization tries to extend a helping hand. It can provide methods that are capable of displaying data more conveniently.

Our intended application areas have in common that they both study the functioning of the brain. More precisely, it is our goal to develop improved visualization techniques that can be applied to data collected by electroencephalography (EEG) and to functional Magnetic Resonance Imaging (fMRI) data. Using EEG, electrical potential differences are detected at a number of electrodes attached to different positions at the scalp surface. These potential differences are a direct consequence of the electrical activity of large groups of neurons within the brain. The potentials are measured about a thousand times per second, sometimes for hours in a row. With an fMRI scanner on the other hand, a value is measured that is related to the blood flow towards the active parts of the brain. Using fMRI, measurements can be performed at tens of millions of specified positions within the brain.

So, although both EEG and fMRI can be used as tools to study brain functioning and they both generate large quantities of data, they possess clearly different qualities. The main distinction is found in their spatial and temporal sensitivity. Although EEG cannot exactly find the spatial location of the brain activity, it can determine the timing of the activity very accurately. On the contrary, fMRI can quite accurately give the location of the source of the activity within the brain, but its temporal sensitivity stays far under the level of EEG.

In our project, we would like first of all to come up with new or improved visualization techniques for EEG researchers. They have been fed with increasing amounts of information by technological improvements in the past few years; more electrodes can nowadays be attached to the scalp than can be analyzed properly. Apart from that, EEG and fMRI can now be recorded simultaneously. To optimally combine the spatially accurate fMRI-information with the temporally accurate EEG-information, a new approach needs to be found to visually assist the human interpreter.

In conclusion, we want to serve two different general aims. In the first place, the new visualization techniques are meant to be appropriate for clinical assessment. Secondly, research fields with data types related to EEG and/or fMRI might also benefit from newly developed methods.

Thesis period: September 2003 - August 2007


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Publications and lectures: M. ten Caat, N.M. Maurits, J.B.T.M. Roerdink, “Tiled Parallel Coordinates for the Visualization of Time-

Varying Multichannel EEG Data”, oral presentation at EuroVis, Leeds UK, 2005

Publications in preparation: M. ten Caat, N.M. Maurits, J.B.T.M. Roerdink, “Tiled Parallel Coordinates for the Visualization of Time-

Varying Multichannel EEG Data”, IEEE Transactions on Visualization and Computer Graphics (user evaluation in progress)

Cooperation with and/or relation to other projects: Discussion in seminars and group meetings with the members of the Scientific Visualization & Computer Graphics group (Groningen). Discussions with clinical EEG experts.

Participation in the study program (attended Lectures, courses and conferences): 10/2004: InterGK Groningen (presentation) 06/2005: InterGK Groningen (attendant) Regular attendance at BCN (mini-) symposia Regular attendance at symposia organized by University Medical Center Groningen Biweekly EEG meetings (BCN Neuroimaging Center, Groningen) Regular attendance at Computer Science colloquia (Groningen) Compulsory BCN courses (BCN Orientation course, BCN poster presentation, BCN


EEG course, BCN fMRI course, BCN Neuroimaging Center

Teaching/supervision/ counseling within the graduate school: Member BCN PhD Student Council

List of stays abroad: 06/2005 EuroVis conference, Leeds, UK



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Dr. Ulrike Dicke, Carl von Ossietzky Universität Oldenburg

Neural models of modulation frequency analysis

Thesis supervisor: Prof. Dr. Dr. Birger Kollmeier (Medizinische Physik, Universität Oldenburg), Prof. Dr. Torsten Dau (Center for Applied Hearing Research, Danish Technical University, DTU)

The thesis aimed at understanding the processing of amplitude modulated (AM) acoustic stimuli in the mammalian auditory system. A biologically motivated neural model of AM processing was developed. The first main component of the model allows for simulating the response properties of cochlear nucleus ideal onset units, a neuron type that is known to encode the modulation frequency of AM stimuli by its distinct temporal responses. The second model component consists of a neural circuit that transforms temporal AM information, provided by the ideal onset model, into a rate-based representation of AM information. This rate -based representation is given by modulation-frequency selective neurons exhibiting bandpass shaped rate modulation transfer functions with different best modulation frequencies. The neural model allows for encoding the modulation content of a variety of AM stimuli. In the third part of the thesis, the model was further extended in order to compare the simulation results to the amplitude modulation filter concept derived from recent psychoacoustical data. Overall, the biologically motivated neural model has been found to be in line with results from both neurophysiological recordings and psychoacoustic concepts and might therefore provide an important step towards a better quantitative understanding of the AM processing principles in the mammalian auditory system.

Thesis period: 01.06.2000 – 17.12.2003 Förderzeitraum im Graduiertenkolleg: 01.06.2000 – 01.06.2003

Publications and Lectures: Dicke, U. (2004) „Neural models of modulation frequency analysis”, Berichte aus der Medizinischen

Physik (Dissertation), Shaker Verlag Aachen. Dicke, U., Dau, T. (accepted) „A functional point-neuron model simulating cochlear nucleus ideal onset

responses“, Journal of Computational Neuroscience

Publications in preparation: Dicke, U., Dau, T., Ewert, S. D., Kollmeier, B. „A neural circuit transforming temporal periodicity

information into a rate-based representation in the mammalian auditory system“, in preparation for Journal of the Acoustical Society of America

Cooperation with and/or relation to other projects: Modulation perception (S.Ewert), Neural coding (M.Bee), EEG from modulated signals (D. Junius)

Participation in the study program (attended lectures, courses and conferences): 6/2004 International Graduate College visit to Tübingen 9/2003 BCN & BCN & Inter-GK Summer School on parallels in visual and auditory

processing (Oodorn, the Netherlands) 5/2003 International Graduate College visit to Copenhagen 8/2001 EGK Summer School on the central auditory system (Bad Zwischenahn,

Germany)


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3/2001 NeuroNord course on Neural Modelling (Bremen, Germany)

Teaching/supervision/ counseling within the graduate school: 2000 – 2005: Supervision in the lab course Psychophysics, Medizinsche Physik,

Universität Oldenburg 10.2002: Lecture in the Neuroscience Seminar, Medizinsche Physik, Universität

Oldenburg 04.2004: Lecture in the Course Auditory Signal Processing and Perception, Center

for Applied Hearing Research, Danish Technical University, DTU. 06.2004: Lecture in the Neuroscience Seminar, Medizinsche Physik, Universität

Oldenburg

List of stays abroad: 2002-2003: Multiple visits at the Center for Applied Hearing Research, Danish

Technical University, DTU, Denmark


Occupation after leaving the graduate school (if applicable): 2004: Research associate, Medizinische Physik, Universität Oldenburg 2005: Unternehmensberatung, Frankfurt


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Dr. Theo Dinklo, Rijksuniversiteit Groningen

Mechano- and electrophysiological studies on cochlear hair cells and superficial lateral line cupulae.

Thesis supervisors: Prof. Dr. D.G. Stavenga, Neurobiophysics, Dr. S.M. van Netten, Neurobiophysics

A fluid jet-producing device has been used to obtain high-resolution measurements of the hydrodynamic behaviour of superficial neuromast cupulae in zebrafish (Danio rerio) larvae. The jet-producing device has been developed consisting of a pressurised fluid-filled container combined with a glass pipette having a microscopically sized tip acting as an orifice. Using a simple mechanical model describing experimental data the key elements of the device are explored showing that the tip resistance is the prime parameter influencing the output response. In addition a calibration method is presented, which allows for the determination of the fluid jet’s frequency dependent characteristics, which can subsequently be used to correct the measured frequency responses of mechanosensory structures for stimulus device artifacts. The fluid jet stimulus was used to vibrate the cupula in zebrafish larvae within a range of frequencies while a laser interferometer is used to measure the resulting displacements with sub-micrometer accuracy. This way frequency responses of the cupula have been obtained. A model previously used to describe the hydrodynamic behaviour of canal neuromasts, fails to provide an accurate description of the superficial neuromast frequency responses. Because of the limited height (~45 µm) with which these cupulae protrude in the surrounding water, they are mainly located within the boundary layer of the skin under the stimulus conditions used. The existing cupula model was therefore extended with frequency-dependent boundary layer properties and compared to the measured data. Further, the detection properties of the superficial neuromasts including the boundary layer effects are compared to canal neuromasts in terms of sensitivity and signal-to-noise ratio.

The signal processing properties of sensory hair cells have been investigated by applying information and estimation theory on measured characteristics of the transducer channel in mouse cochlear hair cells. Instead of determining the current response to a certain bundle deflection, we reversed the point of view and tried to define what the optimal accuracy is with which can estimate the bundle deflection based on the transducer current through a single transducer channel. Besides the channel noise, also the noise produced by the gating spring is taken into account. The optimal accuracy in estimating the hair bundle’s position is found to be 6.5 nm within the 5 kHz bandwidth over which was measured. A surprising finding, bearing in mind that at the threshold of hearing the estimated hair bundle displacement range from fractions of nanometers up to a few nanometer. Possible explanations as to how the hearing organ can reach its exquisite displacement sensitivity even though its individual detection instruments are poorer estimators are discussed.

Thesis period: 06/1998-12/2003, Thesis defense: January 2005


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Publications and lectures:

Publications: Dinklo, T., Van Netten, S.M., Marcotti, W., Kros, C.J. (2003) Signal processing by transducer channels

in mammalian outer hair cells. IN: Biophysics of the cochlea: from molecules to models. Eds. A.W. Gummer, E. Dahlhoff, M. Nowotny, M.P. Scherer. World Scientific. Pp. 73-79.

Van Netten, S.M., Dinklo, T., Marcotti, W., Kros, C.J. (2003) Channel gating forces govern accuracy of mechano-electrical transduction in hair cells. Proc. Natl. Acad. Sci. USA 100, 15510-15515.

” Signal processing by transducer channels in mammalian outer hair cells “, talk held July, 2003 at the International Symposium “Biophysics of Hearing” in Titisee, Germany

Publications in preparation: Dinklo, T and van Netten, S.M. Design and calibration of a fluid jet-producing stimulus device Dinklo, T and van Netten, S.M Superficial neuromast mechanics in the zebrafish (Danio Rerio)

Cooperation with and/or relation to other projects: Regular interaction with the Biomedical Technology group (H. Duifhuis) about research on audiological, hearing and acoustical problems.

Participation in the study program (attended Lectures, courses and conferences): Bcn seminar, weekly during semester, Groningen, including regular presentation of

own work InterGK meetings, monthly, Groningen/Oldenburg International Symposium “Biophysics of Hearing” in Titisee, Germany Mitwintermeeting Association of Research in Otolaryngology 2002, St. Petersburg, Fl,

USA 3 months visit to the lab of Dr. Kros (University of Bristol, UK) to study

electrophysiological techniques

Teaching/supervision/counseling within the graduate school: Teaching courses on neurophysiology and practical courses on electrophysiology (patch-clamping)



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Dipl.-Geophys. Suzan Emiroglu, Carl von Ossietzky Universität Oldenburg

Auditory object recognition in normal (NH) and hearing-impaired listeners (HI) - Psychoacoustic measurements and modeling

Thesis supervisor: Prof. Dr. Dr. B. Kollmeier, Medizinische Physik

The interpretation of auditory scenes in a real acoustical environment is a complex, poorly understood performance of the auditory system, which is significantly disturbed in HI. Therefore, psychoacoustic experiments try to characterise the effective signal processing of the hearing process and to model it quantitatively. A better understanding of the auditory processing deficit in HI can serve as a basis for the enhancement of “intelligent” hearing aids. The aim of the thesis is to contribute substantially to this comprehension by applying and modelling psychoacoustic measurements on timbre perception as one attribute of object discrimination.

Former studies on neurosensory transformation in HI Most of the models that describe hearing processing quantitatively refer only to certain attributes, such as loudness, pitch and binaural hearing. Others, such as PEMO (Göttingen/Oldenburg’s perception model; Dau et al., 1997), are able to describe the effective signal processing of masking and discrimination experiments (Kollmeier, 2002). Most of the existing hearing models assume a non-linear neurosensory transformation of the acoustic signal into an “internal representation”, the details of which are analysed by appropriate stimuli. In the model an “optimal detector” identifies or separates on this internal representation the desired hearing objects, limited by an internal noise. One problem here is the absent “object linearity” (Kollmeier & Derleth, 2001): The cognitive segregation of several acoustic objects requires that the internal representation of one object does not change, if a second is added. This is only valid if the neurosensory processing is approximately linear and time-invariant. The discriminability of hearing objects is closely connected to the linearity of the neurosensory transformation, i.e. a value that is significantly changed in HI. So far the hearing models for sensorineural HI are not further developed. While the negative influence of a sensorineural hearing-loss on nearly all psychoacoustically ascertainable hearing functions is optimally verified (e.g. Moore, 1998), the systematic dependency of the individual hearing functions onto each other is still quite vague. The role of time and frequency resolution is also still controversial (Moore 1998, Launer et al. 1997). The aforesaid effective linearity of object representation is probably violated in HI, because the compressive cochlear processing is disturbed. This absent effective linearity would explain, why sensorineural HI particularly have problems separating desired speech information from undesired background noise in a cocktail party (Kollmeier & Derleth 2001).

Timbre perception as an attribute of scene analysis The interaction of peripheral and neurosensory non-linearity to a resulting effective linearity, which is necessary for object separation, has not yet been sufficiently studied. This is required for a general understanding of object perception in NH and HI, and shall be improved in the framework of the thesis. For this purpose psychoacoustic measurements were and will be performed, which will subsequently be simulated by models. As hearing attribute the timbre of musical instruments is


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studied. Because timbre itself is composed of various temporal and spectral overlaps of sinusoidal tones, HI suffer from a timbre distortion (due to the frequency-dependent hearing loss and possibly the absent object linearity mentioned above). Modelling the experiments with pre-filtered stimuli can show if this timbre distortion is only a secondary factor and is produced by the frequency-dependent hearing loss. On the other hand, still unknown details of the aforesaid effective non-linearity can be elaborated. In order to parameterise the stimuli and thereby acquiring possible differences between HI and NH in terms of (non-)linear perception, synthetic sounds are generated as follows: By linear interpolation of spectral parameters, sounds of musical instruments are cross-faded along several temporal and spectral dimensions, by the stimulus continua are generated between natural instruments.

Procedure and state of the dissertation project The dissertation project started in September 2003 and is currently within its second year. In the first year, after the orientation phase, the procedures and signal processing methods for “morphing” musical instruments were developed by modifying appropriate schemes from the literature. In addition, differences between NH and HI subjects were identified with a pilot experiment in which the subjects rated the similarity of sounds. The experiment showed similar judgments by NH and HI, but some HI seem to have problems in distinguishing certain instrument continua. In the second year, alternative-forced-choice experiments have been carried out, which determine a just-noticeable difference (JND) along several timbre dimensions. They determined that timbre JNDs of HI for certain musical instruments are significantly higher than those of NH. This holds for the instrument continuum where the main physical difference is the spectral centroid. On the other hand, in the continuum where the sounds differ mainly in temporal fluctuation no significant JND differences were found. Because of these instrument-dependent differences, in the next experiments spectral and temporal timbre JND shall be quantifiably separated by stimuli with synthetically imposed spectra. JND measurements in the presence of background noise and possible further experiments will follow. The most important experimental results shall be compared with results by existing hearing models (PEMO), between the end of the second until middle of the third year. The expected discrepancies can give information about the details of the object (non-)linearity with which the models get extended and improved. Finally in the third year, the dissertation shall be finalised as contributions in international peer-reviewed journals.

References: Dau, T. et al. (1997). “Modeling auditory processing of amplitude modulation: I. Detection and masking

with narrow-band carriers.” JASA 102: p. 2892-2905. Kollmeier, B. (2002). “Cocktail-Parties und Hörgeräte: Biophysik des Gehörs.” Physik Journal 1: 39-45. Kollmeier, B., Derleth, R.-P. (2001). “How linear is the auditory system? A model of compression and

expansion based on psychoacoustics for normal and hearing impaired listeners.” In: Proc. of the 12th ISH 2000, Shaker, p. 18-27.

Moore, B.C.J. (1998). “Cochlear hearing loss.” Whurr Publishers, London. Launer, S. et al. (1997). “Modeling loudness growth and loudness summation in hearing-impaired

listeners.” In: Jesteadt & Mahwah (eds) Modeling sensorineural hearing loss. Lawrence Erlbaum Assoc., p.175-185.

Thesis period: September 2003 - September 2006 (projected)

Publications and Lectures: Emiroglu, S., Petersen, N., Rey, D. (2003). “Magnetic properties of sediment in the Ría de Arousa

(Spain): dissolution of oxides and formation of sulfides”, Phys. Chem. Earth (A/B/C), Vol. 29, No. 13-14, p. 947-959.


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Rey, D., Pérez-Guerra, A., Fernández Dávila, A., Mohamed, K. J., Rubio, B., Méndez, G., Emiroglu, S. (2001). “Vicus Magnetofolia - preliminary results.” MAGazine 04: p.2-3.

Emiroglu, S., Kollmeier, B. (2005): “Ähnlichkeits- und JND-Messungen mit gemorphten Stimuli zur Klangfarbenwahrnehmung bei Schwer- und Normalhörenden”, In: Proceedings DAGA 2005, München, in press.

Publications in preparation: Emiroglu, S. and Kollmeier, B. (2005 in prep.). “Morphing as a Method to Determine Just-Noticeable

Differences (JNDs) of Timbre”, in preparation for JASA.

Cooperation with and/or relation to other projects: Cooperation with Dr. D. Pressnitzer (Paris, France), who is working on pitch and

timbre perception in normal hearing and cochlear implant listeners. Cooperation with dissertation project R. Beutelmann (Binaural speech perception in

hearing-impaired listeners). Collaboration and discussions in seminars and group meetings with the members of

the Medical Physics group (Oldenburg, Germany), about 30 scientists who work on measurements and modeling of the auditory system.

Participation in the study program (attended lectures, courses and conferences): 09/03-07/05 attending the regular graduate program, including weekly seminars of

the graduate school and of the medical physics group in Oldenburg (incl. one talk per semester), monthly day seminars of the graduate school in Oldenburg and Groningen (NL) and two summer schools of the graduate school in Odoorn (NL) and Bad Zwischenahn.

03/04 meeting of the German Society of Audiology “DGA”, Leipzig, Germany. 03-05/04 10 week internship at “Hörzentrum”, Oldenburg, Germany. 06/04 visit to the graduate school “Cognitive Neurobiology”, Tübingen, Germany. 06/04 consensus conference for “objective determination of acoustical quality of

(hearing aid) algorithms” by HörTech, Oldenburg, Germany. 08/04 intern. conference “Auditory Scene Analysis and Speech Perception by Human

and Machine” by Hanse Wissenschaftskolleg, presented poster “Psychoacoustic Measurements on Timbre Perception with Morphed Musical Stimuli”, Delmenhorst, Germany.

03/05 counter-visit of the graduate school “Cognitive Neurobiology” from Tübingen (organisation and realisation with talks and lab tour), Oldenburg, Germany.

03/05 winter school “Medical Acoustics and Audiology”, Pichl, Austria. 08/05 meeting of the German Society of Acoustics “DAGA 2005”, given talk:

“Similarity- and JND-Measurements on Timbre Perception in hearing-impaired and normal listeners”, Munich, Germany.

Teaching/supervision/counseling within the graduate school: 02/04 one week tutoring the project “Transfer of speech signals with LPC” in the

advanced lab course “Digitale Signalverarbeitung”. 09/04 two days tutoring psychoacoustic measurements in the advanced lab course

“Neurosensorik”. 10/04-07/05 speaker of the Ph.D. students in the graduate school.

List of stays abroad: Regular meetings with the Groningen members of the international graduate school. 03/05 winter school “Medical Acoustics and Audiology”, Pichl, Austria. 07/05 meeting with Dr. D. Pressnitzer and the group “Perception auditive”, Paris.



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Drs. Just J. van Es, Rijksuniversiteit Groningen

Colour constancy; retina or cortex?

Thesis supervisors: dr. F.W. Cornelissen, dr. T.L. Valdusich, prof. dr. A.C. Kooijman, prof. dr. J.M.M. Hooijmans

Colour constancy is the tendency for colours to look the same despite different illumination conditions. Many psychophysical studies have shown that perceptual colour constancy is only a weak phenomenon, with perceived colours changing in the direction of an illumination shift. Subjects are however able to correctly attribute the cause of a perceived colour change, which is either a change in the material viewed (reflectance change) or a change in the illumination. This attribution is made based on information offered by spatial colour relations within a scene, such as cone-contrast ratios, and is therefore known as relational colour constancy.

In a functional Magnetic Resonance Imaging (fMRI) experiment we tested how the Blood Oxygen Level Dependent (BOLD) signal in colour sensitive areas in visual cortex is influenced by these two types of colour constancy. Subjects viewed sequentially presented pairs of radial colour checkerboards (fig. 1A). The first stimulus was simulated to be under a neutral reference spotlight covering the radial colour pattern; the second stimulus was simulated to be under a coloured test spotlight. Presented in a classical block design, subjects were either instructed to judge whether the colour of the ring remained the same across the illumination interval (equal colour judgement) or whether the perceived change in ring colour was consistent with a change in the colour of the spotlight (illuminant consistent judgement). The first task measures perceptual colour constancy, the second task measures both perceptual and relational colour constancy. As a control task, subjects viewed exactly the same stimuli, but now with an overlay of letters on which they performed a letter task that drew attention away from the actual colour of the stimuli. Subjects performed all tasks for colour and luminance stimuli.

Colour constancy indices showed that colour constancy was around 20% when subjects made local colour judgements during the equal colour judgement task, and that it increased to about 60% when subjects made relational colour judgements during the illuminant consistent judgement task. Colour constancy was equal across colour and luminance stimuli.

During the fMRI data-analysis, clusters in visual cortex were selected that showed colour sensitivity, which meant a stronger fMRI signal during all tasks with coloured stimuli, compared with all tasks with luminance stimuli (see fig. 1B for an example). Using this classical delineation technique in each subject separately, Regions of Interest (ROIs) were successfully delineated in 12 out of 18 hemispheres (9 subjects). The average level of activation within these ROIs during all tasks was then subjected to statistical testing. In figure 1C can be seen that for both colour and luminance stimuli, there was a significant increase in fMRI signal strength when subjects performed one of the two judgement tasks (equal colour judgement or illuminant consistent judgement) compared to the letter control task. There was however no difference between the two types of judgement, both for colour and luminance stimuli. The BOLD signal was equally strong regardless whether subjects judged local colour or whether subjects made relational colour judgements.


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Preliminary results of brain areas outside visual cortex (data not shown) seem to suggest that relational colour judgements are more mediated by parietal brain regions, while local colour judgements are more mediated by medial frontal brain regions.

Thesis period: August 2003 – July 2007

Publications: Boucard, C.C., Van Es, J.J., Maguire, R.P., Cornelissen, F.W. (2005). Functional magnetic resonance

imaging of brightness induction in the human visual cortex. Neuroreport, 16(12):1335-1338 Van Es, J.J., Vladusich, T.L., Cornelissen, F.W. (in preparation). Local and relational judgement of

surface colour. Van Es, J.J., Vladusich, T.L., Cornelissen, F.W. (in preparation). Fast local and global judgements of

surface colour; an fMRI-study of the effect of relational colour constancy on the BOLD signal in human visual cortex.

Cooperation with and/or relation to other projects: Projects with R. van den Berg of the Roerdink/Petkov group on monitor calibration and 3-D colour constancy paradigms. This dissertation project has a relationship concerning the studied questions as well as the employed methods to the projects of Prof. Dr. Greenlee (Oldenburg, projects of R. Weerda & I. Vallines).


Courses Brain Voyager 2003 at the University of Maastricht. Motor Control for vision Scientist 2004 Lunteren


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Conferences 28th European Conference on Visual perception (2005), (oral presentation) 27th European Conference on Visual perception (2004), (poster presentation) 26th European Conference on Visual perception (2003)



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Dr. Stephan Ewert, Carl von Ossietzky Universität Oldenburg

Auditory spectro-temporal processing in the envelope-frequency domain: Experiments and models

Thesis supervisor: Prof. Dr. Dr. Birger Kollmeier, Carl von Ossietzky Universität Oldenburg, Medizinische Physik, D-26111 Oldenburg, Germany

The main goal of the thesis was to obtain a deeper understanding of the basic mechanisms and coding principles underlying the processing and perception of envelope fluctuations. The experimental paradigms presented in the different chapters addressed specific aspects of envelope processing that allowed for a step-by-step characterization of these mechanisms.

Basic studies of the processing of spectral components in the audio-frequency domain have often been associated with questions related to the frequency selectivity of the peripheral auditory system, intensity coding, and combined spectro-temporal effects when more complex sounds were analysed. In analogy, the current thesis attempted to characterize the processing of the envelope of sounds in terms of i) envelope-frequency selectivity, ii) the coding of amplitude-modulation depth, and iii) the processing of complex modulations. Quantitative model predictions were obtained in the different chapters. It was shown that modulation masking, detection and discrimination, as well as the processing of complex envelope waveforms can be successfully accounted for by a relatively simple functional model that used only a very small number of parameters.

Characterizing frequency selectivity for envelope fluctuations Three detection experiments were performed to directly derive the bandwidth and the shape of auditory modulation filters in terms of a critical band concept in the envelope-frequency domain. The experimental paradigms were adopted from classical studies in the audio-frequency domain and were transposed to the envelope-frequency domain. The data were compared to predictions of the envelope power spectrum model (EPSM) which is defined in this chapter. The parameters of bandpass modulation filters were adjusted to account for the various modulation detection and masking data.

External and internal limitations in amplitude-modulation processing The role of internal and external limitations in amplitude-modulation (AM) detection and discrimination was addressed. The effects of external noise (as introduced by stochastic stimuli such as random-noise carriers) can be separated from effects of internal-noise processes that limit resolution in conditions with deterministic stimuli (such as pure-tone or frozen-noise carriers). AM-depth discrimination and AM detection with random and deterministic carriers were investigated. In addition, AM masking was investigated in conditions where the degree of variability of a noise masker was changed, such that conditions ranging from entirely frozen to entirely random were tested. The experimental data were described in terms of the envelope power spectrum model established in the first chapter of the thesis and compared to predictions obtained with the signal processing model by Dau et al. [J. Acoust. Soc. Am. 102, 2892–2905. (1997)].


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Spectro-temporal processing in the envelope-frequency domain Modulation masking was investigated with different stimulus types for the signal and the masker in order to examine whether beats between modulations play the same role in tone-in-noise, noise-in-tone and tone-in-tone masking as they do in corresponding masking experiments in the audio-frequency domain. The new concept of the ``venelope'' was introduced which is defined as the envelope of the (ac-coupled) envelope of the stimuli, and is useful to describe the effect of beats between concurrent envelope components of an arbitrary waveform. In addition, the question to what extent envelope and venelope fluctuations interact with each other when they lie in a similar range of frequencies was addressed. Based on the experimental data, a general model structure for the processing of envelope and venelope fluctuations was proposed.

Modulation masking produced by complex tone maskers The processes underlying the extraction of the venelope in the auditory system was further investigated. Venelope-phase sensitive experiments were conducted in normal-hearing and sensorineural hearing-impaired listeners. The experiments are motivated by an earlier study by Moore et al. [J. Acoust. Soc. Am. 106, 908-918. (1999)] where the non-linear processing in the healthy cochlea was suggested as the possible origin for a demodulation of envelope beats to the envelope-frequency domain. Since cochlear damage is assumed to result in a reduction or loss of the compressive nonlinearity in the input-output function of the basilar membrane, the experiment provided a critical test for the role of the cochlear nonlinearity in complex envelope processing.

Mechanisms of envelope-frequency selectivity It was tried to clarify the nature of frequency selectivity in envelope processing. The remaining question was whether the frequency selectivity observed in all the different modulation detection and masking experiments reflected a ``true'' limited-resolution spectral decomposition of the stimulus envelope, or whether it simply reflected a selective process that is tuned to different repetition rates in the envelope. This question was addressed by measuring detection thresholds for a sinusoidal signal modulation in the presence of a squarewave or a sinusoidal masker modulation, both having the same rate of repetition but different content in the envelope spectrum.

State of the dissertation project: completed 12/2002

Thesis period: 05/1999 – 12/2002, Associate member of the "European Graduate School for Neurosensory Science, Systems and Applications“ 05/2000 – 06/2003


Peer reviewed Articles: Stein, A., Ewert, S. D., and Wiegrebe, L. (2005). “Interaction between pitch and modulation perception

in broadband stimuli: A test of the autocorrelation and modulation filterbank model,” J. Acoust. Soc. Am., in press.

Füllgrabe, C., Moore, B. J. C., Demany, L., Ewert, S. D., Sheft, S., and Lorenzi, C. (2005). “Modulation masking produced by second-order modulators,” J. Acoust. Soc. Am. 117, 2158-2168.

Oxenham, A. J., and Ewert, S. D. (2005). “Estimates of auditory filter phase response at and below characteristic frequency (L),” J. Acoust. Soc. Am. 117, 1713-1716

Ewert, S. D., and Dau, T. (2004). “Internal and external limitations in amplitude-modulation processing,” J. Acoust. Soc. Am. 116, 478-490.

Verhey, J. L., Ewert, S. D., and Dau, T. (2003). “Modulation masking produced by masker modulation tone complexes,” J. Acoust. Soc. Am. 114, 2135-2146.


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Ewert, S. D., Verhey, J. L., and Dau, T. (2002). “Spectro-temporal processing in the envelope-frequency domain,” J. Acoust. Soc. Am. 108, 2921-2931.

Ewert, S. D., and Dau, T. (2000). "Characterizing frequency selectivity for envelope fluctuations," J. Acoust. Soc. Am. 108, 1181-96.

Conference proceedings and book chapters: Dau, T., Ewert, S. D., and Oxenham, A. J. (2005). "Effects of concurrent and sequential streaming in

comodulation masking release,” in Auditory Signal Processing – Physiology, Psychoacoustics, and Models, edited by D. Pressnitzer, A. de Cheveigne, S. MacAdams, and L. Collet., 335-343.

Ewert, S., Verhey, J., and Dau, T. (2000). "Across-channel processing of amplitude modulation," Fortschritte der Akustik DAGA 2000, 328--329.

Verhey, J., Ewert, S., and Dau, T. (2000). "Modulationsverarbeitung im Gehör: Autokorrelation versus Filterbank," Fortschritte der Akustik DAGA 2000, 296--299.

Ewert, S. D., and Dau, T. (1999). "Psychophysical tuning in auditory AM processing,” in Psychoacoustics, Physiology and Models of Hearing, edited by T. Dau, V. Hohmann, and B. Kollmeier (World Scientific, Singapore), 73-76.

Conference talks: Verhey, J. L., Ewert, S. D., and Dau, T. (2004). "The processing of complex envelopes in the normal-

hearing and the hearing-impaired auditory system," Joint CFA/DAGA Convention. Dau, T., Ewert, S. D., and Oxenham, A. J. (2004). "Effects of concurrent and sequential streaming in

comodulation masking release," Joint CFA/DAGA Convention. Ewert, S. D., and Dau, T. (2004). “Envelope Processing in the auditory system: Spectral

decomposition or Temporal Periodicity Analysis," Assoc. Res. Otolaryngol. Abs.: 805. Ewert, S. D., Verhey, J., Kollmeier, B., and Dau, T. (2000). „Across-channel processing of amplitude

modulation," J. Acoust. Soc. Am. 107, 2899.

Conference abstracts and posters: Hau, O., Ewert, S. D., and Dau, T. (2005). “A unified view of the temporal-window and the adaptation-

loop model in conditions of forward- and simultaneous masking,“ J. Acoust. Soc. Am. 117, 2536. Piechowiak, T., Ewert, S. D., and Dau, T. (2005). “Modeling comodulation masking release using an

equalization cancellation mechanism,” J. Acoust. Soc. Am. 117, 2536. Nelson, P. C., Ewert, S. D., Carney, L. H., and Dau, T. (2005). “Comparison of intensity discrimination,

increment detection, and comodulation masking release in the envelope and audio-frequency domains,” J. Acoust. Soc. Am. 117, 2535

Füllgrabe, C., Moore, B. J. C., Demany, L., Ewert, S. D., Sheft, S., and Lorenzi, C. (2004). “Modulation masking produced by 2nd-order AM: Effects of AM Carrier Frequency and 2nd-order AM Phase,” Assoc. Res. Otolaryngol. Abs.: 836.

Verhey, J. L., Ewert, S. D., and Dau, T. (2003). "Processing of Complex Amplitude Modulation in Normal-Hearing and Hearing-Impaired Listeners,'' Assoc. Res. Otolaryngol. Abs.: 1482.

Ewert, S. D., and Dau, T. (2003). “External and Internal Limitations in Amplitude-Modulation Processing,” Assoc. Res. Otolaryngol. Abs.: 1484.

Ewert, S. D., and Oxenham, A. J. (2002). “Effects of Masker Phase Curvature for On- and Off-Frequency Simultaneous and,” Assoc. Res. Otolaryngol. Abs.: 72.

Ewert, S. D., Dau, T., Verhey, J.L., and Kollmeier, B. (2001). “Asymmetry of masking in the envelope-frequency domain," J. Acoust. Soc. Am. 109, 2466.

Verhey, J. L., Ewert, S. D., and Dau, T (2001). “Modulation masking produced by masker modulation tone complexes,” J. Acoust. Soc. Am. 109, 2466.

Ewert, S. and Dau, T. (1999). "Frequency selectivity in amplitude-modulation processing," J. Acoust. Soc. Am. 105, 1234.

Publications in preparation: Ewert, S. D. and Bellman, M. A. (2005). “Frequency selectivity in vertical whole-body vibration

detection,” for J. Acoust. Soc. Am. Ewert, S. D. (2005) “Envelope Processing in the auditory system: Spectral decomposition or Temporal

Periodicity Analysis,” for J. Acoust. Soc. Am.

Cooperation with and/or relation to other projects: Oxenham, A. J., “Estimates of auditory filter phase response at and below

characteristic frequency,” Massachusetts Institute of Technology, Cambrigde, MA, USA.


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Stein, A., Wiegrebe, Lutz, “Interaction between pitch and modulation perception in broadband stimuli: A test of the autocorrelation and modulation filterbank model,” LMU München.

Dicke, U., “Neural models of modulation frequency analysis in the auditory system”, University of Oldenburg.

Bellman, M. A., “Frequency selectivity in vertical whole-body vibration detection”, University of Oldenburg.

Participation in the study program (attended lectures, courses and conferences): attending the regular graduate program, including weekly seminars of the graduate school and of the medical physics group in Oldenburg (incl. one talk per semester), monthly day seminars of the graduate school in Oldenburg and Groningen (NL) and a summer school of the graduate school in Bad Zwischenahn.

Teaching/supervision/ counseling within the graduate school: Contribution and teaching at lab courses for advanced students of physics at the

University of Oldenburg: “Physical Measurements and Digital Signal Processing” and “Psychophysics, Neurosensory and Auditory Signal Processing”, 1999-2003.

Counseling/Co-supervision of PHD thesis: Ulrike Dicke, “Neural models of modulation frequency analysis in the auditory system”, University of Oldenburg, 2003.

List of stays abroad: 3/2001 - 6/2001 Visiting Scientist at the Research Lab of Electronics at the

Massachusetts Institute of Technology, Cambrigde, MA, USA. Collaboration with Dr. A. Oxenham.


Occupation after leaving the graduate school (if applicable): 07/2005-current Research associate “Wissenschaftlicher Angestellter” at the

University of Oldenburg. 07/2003-06/2005 Assistant Professor at the Centre for Applied Hearing Research,

Oersted DTU, Technical University of Denmark, Lyngby, Denmark. 05/2002-06/2003 Research associate “Wissenschaftlicher Angestellter” at the

University of Oldenburg.


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Dipl.-Phys. Sandra Fobel, Carl von Ossietzky Universität Oldenburg

Relation between sensorineural hearing impairment and steady-state amplitude modulation following responses

Thesis supervisor: Prof. Dr. Dr. Birger Kollmeier, Dr. Torsten Dau, Medical physics group

Among other problems, a sensorineural hearing loss is usually associated with:

• A reduced dynamic range, which is known as ‘recruitment phenomenon’. The hearing-impaired listener cannot hear low-level sounds but perceives high-level sounds as loud as a normal-hearing listener. This distortion effect is caused mainly by the loss of the active amplification (produced by outer hair cells in the cochlea) which enhances low-level sounds but have no effect on high-level sounds.

• The deterioration of binaural processing which causes the ‘cocktail party effect’, where the ability to understand speech in a noisy environment is markedly reduced.

The aim of the current project is both a more profound understanding of the impairment in auditory adaptation and spatial perception and a better objective method to quantify them, i.e. by using evoked potentials in electroencephalography (EEG). The results may enable better hearing aid fitting especially when feedback from the patients is not obtainable. This is particularly important for newborns and infants with hearing problems.

The first part of this thesis is concerned with the recruitment phenomenon. Loudness perception is usually measured psychoacoustically by methods like loudness scaling or magnitude estimation. Since infants and very young children cannot perform these tasks, an objective method is needed, e.g. auditory brainstem potentials (ABR). They arise up to ten milliseconds after stimulus presentation and are often used for estimating hearing impairment. However there seems to be no direct relation between loudness and the amplitude or phase of the auditory brainstem potentials (e.g. Wegner, O., Dau, T., Verhey, J., and Kollmeier, B. (1998), "Untersuchungen zu Lautheits-Korrelaten in akustisch evozierten Potentialen," in Fortschritte der Akustik - DAGA 98 (Deutsche Gesellschaft für Akustik e.V., Zürich), pp. 308.).

A more promising method for objectively assessing loudness perception seems to be the recording of the ‘amplitude modulation following response’ (AMFR), which is evoked by a continuously presented sinusoidally modulated stimulus. The recorded response follows the modulation frequency of the stimulus but is evoked by neurons tuned to the carrier frequency. This allows an objective and frequency-specific assessment of the hearing threshold (Kuwada, 1986, Hearing Research, 21, p. 179-192; Griffiths et al., 1991, Ear and Hearing, 12(4), p. 235-241.). The existing literature is for the most part concerned with the general dependence of the AMFR on experimental parameters such as level, carrier frequency and so forth for normal-hearing listeners. Kuwada (1986, Hearing Research, 21, p. 179-192) showed that for hearing-impaired listeners an increased level results in an abnormally high amplitude rise in the area where the hearing impairment is greatest. Since the loudness function for hearing-impaired listeners is steeper in frequency regions of hearing loss than in


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regions with better hearing, a correlation between loudness perception and AMFR might exist. This relationship will be investigated in the current study.

Five normal-hearing and five hearing-impaired listeners participated in this study, which consisted of three experiments:

In standard audiological testing pure tones are used to estimate the hearing threshold. However, amplitude-modulated (AM) tones are used to measure the AMFR. Thus, it is of interest, whether pure tones and AM tones have the same hearing threshold. In the first experiment, the respective hearing threshold was determined using a three-interval, three-alternative forced-choice paradigm. The threshold of AM tones with carrier frequencies of 0.5, 1, 2, 4, and 8 kHz, modulated with 40 and 80 Hz, were compared with the threshold of the corresponding pure tones. The results showed no significant differences between the hearing thresholds for the two signal groups.

Third-octave narrow-band noises are typically used as stimuli in loudness-scaling experiments to assess the loudness function. Therefore, it is important to assess the loudness function for both, third-octave narrow-band noises and AM tones to be able to investigate a possible correlation between loudness perception and AMFR. The adaptive categorical loudness scaling (Brand and Hohmann, 2002, J. Acoust. Soc. Am., 112(4), p. 1597-1604) was used to assess the perceived loudness as a function of level. The resulting loudness functions of AM tones with carrier frequencies of 0.5, 1, 2, 4, and 8 kHz, modulated with 40 and 80 Hz, were compared with the ones of third-octave noise bands using the corresponding centre frequencies. The results showed no systematic differences between the loudness functions of AM tones and third-octave narrow-band noises.

The results of the first two experiments indicate that a direct comparison of the psychophysical data (hearing threshold and loudness function) with the AMFR data is valid. In the third experiment the AMFR were measured using the same AM parameters as in the first two experiments. The levels were equally spaced between the hearing threshold and the highest level accepted by the individual subject. The 40-Hz AMFR were detectable down to the hearing threshold and generally had higher amplitudes than the 80-Hz AMFR. For each subject it was possible to fit the amplitude-level function of the 40-Hz AMFR to the corresponding loudness function using a linear transformation. The lower amplitude of the 80-Hz AMFR data resulted in a very poor detectability. Thus, the correlation between the amplitude-level function of the AMFR and the loudness function was much lower for the 80-Hz AMFR data. However, since the basic EEG noise of the different subjects is quiet different, a general prediction of recruitment just based on AMFR amplitude-level function is not possible right now. Another problem is the large difference in the AMFR amplitude between different subjects. This "standardisation problem" still has to be solved to be able to get reliable information about the loudness perception just using AMFR measurement.

Thesis period: 01.07.2000 – 15.11.2003. Stipend received from the EuroGK : 01.07.2000 – 15.02.2003, 16.07.2003-15.11.2003 Abort of thesis project due to maternship/ family founding

Cooperation with and/or relation to other projects: Cooperation with dissertation project D. Junius (evoked potentials)


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Collaboration and discussions in seminars and group meetings with the members of the Medical Physics group (Oldenburg, Germany) who work on measurements and modeling of the auditory system.


Attended conferences: DGA, 27.02.2002 – 02.03.2002, Zuerich, Switzerland Summerschool "Psychophysics, physiology and models of the central auditory

system",12.08.2001-16.08.2001, Bad Zwischenahn, Germany Start-up symposium of the EuroGK, 08./09.09.2000, Kloosterburen, Netherlands.

(Own talk has been given)

Attended seminars: • Non-regular: Einführungskurs “Medienkompetenz für WissenschaftlerInnen“, 20.09.2001-

22.09.2001, Berlin, Germany DFG Seminar “Das Wissen der Forschung – verständlich für Laien” 17.07.2001-

18.07.2001, Kiel, Germany. XIII. Winterschule für Medizische Physik: Audiologie und Medizinische Akustik,

15.01.2001-19.01.2001, Pichl/Steiermark, Austria. Practical course on neuroscience, 18.-29.09.2000, Oldenburg, Germany - (Own talk

has been given) Summerschool BCN, 5.07.2000, Groningen, Netherlands • Regular: Seminar of the EuroGK, Fridays, 10-12,Oldenburg, Germany - (Own talk has been

given) ‘Monday meetings’, once a month, alternating between Oldenburg, Germany and

Groningen, Netherlands – (Own talk has been given)

Teaching/supervision/ counseling within the graduate school: Lab course on neuroscience, September 2001, Oldenburg, Germany Lab course on neuroscience, September 2002, Oldenburg, Germany

List of stays abroad: Research stays 12/2000, Centre for the Neural Basis of Hearing, Cambridge, Great Britain



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LA Biol. Martin Greschner, Carl von Ossietzky Universität Oldenburg

The temporal structure of retinal ganglion cell activity during natural stimulation, especially during eye movements.

Thesis supervisor: apl. Prof. Dr. Josef Ammermüller, Prof. Dr. Reto Weiler, Neurobiology

Recognition of visual stimulus features depends on the flow of action potentials from retinal ganglion cells to the brain. The basic features of time-varying stimuli can be estimated from the activity of the ganglion cell population by using artificial neural networks, linear decoders or discrimination analyses (1, 2). With increasing numbers of incorporated cells the reconstruction results of time-varying stimuli saturate at a low level when only rate information is included. By contrast, stimulus estimation is nearly perfect when an external reference signal temporally locks the estimation procedure to the time intervals following each stimulus change (2). With this time-locked procedure, latency differences and the initial spike rate are included into each single estimation. However, external reference signals are not available with the possible exception of efference copies at saccades. Another possibility to integrate the spike timing into the estimation is the usage of internal reference signals and thereby the usage of relative latency.

During phases of fixation, while conscious controllable body and eye movements are almost completely missing, small fixational eye movements are still present. These fixational eye moments therefore produce a permanent but small movement of the optical picture on the retina. We have measured fixational eye and head movements of the turtle, and determined their effects on the activity of retinal ganglion cells by simulating the movements on the isolated retina. We showed that ganglion cells respond mainly to components of periodic eye movements that have amplitudes of roughly the diameter of a photoreceptor, whereas drift or small head movements have little effect. Cells that are located along contrast borders are synchronized, which reliably signals a preceding movement. In an artificial neural network, the estimation of spatial frequencies for various square wave gratings improves when time-locked to this synchronization. This could potentially improve stimulus feature estimation by the brain.

Many ganglion cell types also respond to a simple contrast step with a complex time structure. These ganglion cells do not respond with continuous modulation of the spike frequency, instead they react with several distinct spike bursts. These burst patterns are described as oscillatory or rhythmic patterns in cold and warm blooded species (3). The pattern changes in a systematic way in number and timing of the bursts as a function of intensity. Especially the relative latency between the bursts

Fig. 1. Histogram of a turtle ganglion cell response to a drifting contrast border in comparison to the same drift with a superimposed periodic eye moment (tremor).


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could be shown to be potentially useful in stimulus estimation. To study the mechanisms leading to this rhythmic ganglion cell activity, we designed two computational models of different abstraction levels. Warland DK., Reinagel P, Meister M (1997). Decoding visual information from a population of retinal

ganglion cells. J. Neurophysiol. 78, 2336-2350. Fernandez E, Ferrandez JM, Ammermüller J, Normann RA. (2000). Population coding in spike trains

of simultaneously recorded retinal ganglion cells. Brain Res. 887, 222-229. Ariel M, Daw NW, Rader RK (1983). Rhythmicity in the rabbit retinal ganglion cell responses. Vision

Res. 23, 1485-1493. The dissertation project is in its final state.

Thesis period: 15.12.2000-1.10.2005 (projected), 15.12.2000-31.3.2001 (stipend received)


Conference Abstracts: Thiel A, Greschner M, Ammermüller J (2005). Retinal ganglion cell burst patterns are reproduced by a

computational model of intraretinal processing. In Proceedings of the 6th Meeting of the German Neuroscience Society, eds: H. Zimmermann and K. Krieglstein, Neuroforum 2005, 1 Suppl.:165B

van Ahrens L, Ahlers MT, Greschner M, Gundelfinger ED, Brandstätter JH, Brauner D, Ammermüller J (2005). Comparison of retinal ganglion cell responses from Bassoon deficient and wild type mice. In Proceedings of the 6th Meeting of the German Neuroscience Society, eds: H. Zimmermann and K. Krieglstein, Neuroforum 2005, 1 Suppl.:166B

Ammermüller J, Greschner M, Thiel A (2004). Interburst intervals in temporally structured responses of retinal ganglion cells improve stimulus intensity estimation. In FENS Forum Abstracts, Vol. 2. Federation of European Neuroscience Societies. Abstract A194.2.

Thiel A, Greschner M, Ammermüller J (2004). A retina model generating ganglion cell burst sequences with realistic temporal structure and intensity dependence. In FENS Forum Abstracts, Vol. 2. Federation of European Neuroscience Societies. Abstract A194.32.

Thiel A, Greschner M, Ammermüller J (2003). The temporal structure of retinal ganglion cell responses and its relation to intraretinal processing. In 2003 Abstract Viewer, Society for Neuroscience.

Ammermüller J, Greschner M, Thiel A, Voges N, Bongard M, Fernández E (2003). Temporal structure of signal processing in the retina. In Europ Biophys J; 32(3):180.

Greschner M, Thiel A, Ammermüller J (2003). Temporal structure of retinal ganglion light responses improves stimulus estimation. In Proceedings of the 29. Göttingen Neurobiology Conference; Thieme; Stuttgart.

Thiel A, Greschner M, Eurich CW, Ammermüller J (2003). Stimulus velocity reconstructed from retinal ganglion cell activity using Bayes' method. In Proceedings of the 29. Göttingen Neurobiology Conference; Thieme; Stuttgart.

Publications in preparation: Greschner M, Thiel A, Ammermüller J (2005). The temporal structure of retinal ganglion cell light

responses improves intensity estimation., in preparation Thiel A, Greschner M, Ammermüller J (2005). Retinal ganglion cell burst patterns are reproduced by a

computational model of intraretinal processing., in preparation

Cooperation with and/or relation to other projects: Cooperation with dissertation projects: Tim Schubert, Jennifer Shelley, Mark Pottek Collaboration and discussions in seminars and group meetings with the members of

the retina neurobiology group (Oldenburg) and the vision physiology group (Groningen).

Participation in the study program (attended lectures, courses and conferences): 06/2002-07/2005: attended the regular graduate program, including weekly seminars

of the graduate school and of the Neurobiology lab in Oldenburg 06/2002-07/2005: regularly attended monthly meetings Groningen and Oldenburg


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02/2005: 6th Meeting of the German Neuroscience Society, Göttingen 06/2004: FASEB meeting "Retinal Neurobiology", Saxtons River, VT, USA 07/2004: 4th International Meeting Substrate-Integrated MEAs, Reutlingen 10/2003: Society for Neuroscience 33rd Annual Meeting, New Orleans, LA,USA 09/2003 InterGK Workshop in Klosterbuuren, Odoorn, Netherlands 06/2003: 5th Meeting of the German Neuroscience Society, Göttingen

List of stays abroad: Regular meetings with the Groningen members of the international graduate school.



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Aave Hannus, MsC, Rijksuniversiteit Groningen

Interactions of top-down and bottom-up information in visual search

Thesis supervisor: Frans W. Cornelissen, Harold Bekkering (Radboud University Nijmegen)

While searching for objects in environment, we have to combine information from multiple visual modalities such as color and orientation. While it is generally assumed that features are first processed independently prior to an integration stage, physiological findings suggest existence of mechanisms tuned to more than one modality. Presently, little is known about the role such mechanisms play in visual search. As a first step towards answering this question, we test to what extent features are processed independently in conjunction search.

Participants searched for objects that combined color and orientation information while their eye-movements were recorded. Prior to main experiment, we matched color and orientation discriminability; for each participant, we made sure that in feature search 70% of the saccades were likely to go to correct target stimulus independent of the feature to be searched. In contrast to this symmetric single feature discrimination performance, the conjunction search task showed an asymmetry in feature discrimination performance (Fig. 1). We found that in conjunction search similar percentage of saccades went to correct color as in feature search, but much less often to correct orientation. Accuracy of orientation discrimination is thus contingent on whether simultaneous color discrimination is required as well, a finding in conflict with independent feature processing. Similar results were obtained for color and size combinations. We propose that during the search for combinations of features, saccade targets are selected using information from visual channels conjunctively tuned for color and orientation/size. Therefore, important change in presently dominant visual search models may be necessary.

Fig. 1. Mean response accuracy (N = 6) plotted as a function of the search task. In Conjunction Ssearch the orientation discrimination accuracy decreased significantly

Single Feature Search Conjunction SearchTask

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Colour Correct Orientation Correct


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compared to Single Feature Search, while color discrimination accuracy remained approximately equal in both search tasks.

Thesis period: Start 01.01.2002, expected end 01.01.2006

Publications and lectures: Hannus, A., Cornelissen, F. W., Lindemann, O. Bekkering, H. (2005). Selection-for-action in visual

search. Acta Psychologica, 118, 171-191. Hannus, A., Neggers, S.F.W., Cornelissen, F.W. & Bekkering, H. (2005). Selective attention for action: New evidence from visual search studies. In G. Humphreys & J. Riddoch (Eds.), Attention and performance: Attention in action (pp.131-149).

Psychology Press Raudsepp L, Kais K, Hannus A. (2004). Stability of physical self-perceptions during early adolescence.

Pediatric Exercise Science, 16, 138-146. Raudsepp, L., Liblik, R., & Hannus, A. (2002). Children's and adolescents’ physical self-perceptions as

related to moderate to vigorous physical activity and physical fitness. Pediatric Exercise Science, 14, 97-106.

Podar, I., Hannus, A. & Allik, J. (1999). Personality and affectivity characteristics associated with eating disorders: A comparison of eating disordered, weight-preoccupied, and normal samples. Journal of Personality Assessment, 73, 133-147.

Published conference theses: Hannus, A., Bekkering, H., & Cornelissen, F.W. (2005). Effects of feature precuing in the conjunction

search of colour and orientation. Perception (suppl) 34, 155. Van den Berg, R., Hannus, A., Roerdink, J. B. T. M., & Crnelissen, F. W. (2005). A colour – size

processing asymmetry in visual conjunction search. Perception (suppl) 34, 132. Hannus, A., Bekkering, H., Drost, E., Bontjer, R., & Cornelissen, F. (2004). Feature processing

asymmetry in a colour and orientation conjunction-search task. Perception (suppl) 33, 13. Hannus, A., Cornelissen, F.W., & Bekkering, H. (2003). Action related intentional effects in a visual

search task. Perception (suppl) 32, 65. Hannus, A. & Allik, J. (2002). Developmental changes in performing visual-search tasks. Perception

(suppl) 31, 172. Allik, J., Toom, M., Kreegipuu, K., & Hannus, A. (2000). A new powerful method for the study of

feature binding in conjunction visual search. Perception (suppl) 29, Suppl. S, 12.

Cooperation with and/or relation to other projects: Project R. van den Berg, psychophysical measurement, statistical analysis (groups F. Cornelissen and J. Roerdink).


Courses BrainVision Analyzer (EEG) (2004), F. C. Donders Centre for Cognitive Neuroimaging, The Netherlands. Tool-kit of Cognitive Neuroscience 2003, F. C. Donders Centre for Cognitive Neuroimaging, The Netherlands. MatLab 6.0, (2002), University of Groningen, The Netherlands. Functional MRI (2002), University of Groningen, The Netherlands. InterGK meeting in Groningen, June 2005, The Netherlands.

Conferences Hannus, A., Cornelissen, F. W., & Bekkering. H. Action related intentional effects in visual search. Poster presentation. 14th conference of European Society for

Cognitive Psychology, August-September 2005, the Netherlands. Hannus, A., Bekkering, H., & Cornelissen, F.W. Efects of feature precuing in the

conjunction search of colour and orientation. Poster presentation. 28th European Conference on Visual Perception, August 2005, Spain.


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Van den Berg, R., Hannus, A., Roerdink, J. B. T. M., & Crnelissen, F. W. A colour – size processing asymmetry in visual conjunction search. Poster presentation. 28th European Conference on Visual Perception, August 2005, Spain.

Hannus, A., Bekkering, H., & Cornelissen, F.W. Competition between features in visaul search. Oral Presentation. InterGK meeting in Groningen, June 2005, The Netherlands.

Hannus, A., Bekkering, H., & Cornelissen, F.W. Competition between colour and orientation: effects of precuing in the search for visual features. 4th Annual Conference of Estonian Centre of Behavioural and Health Sciences, May 2005, Pärnu, Estonia.

Hannus, A., Cornelissen, F. W., & Bekkering. H. Action related intentional effects in visual search. Poster presentation. 3rd BPS Seminar “Action and Perception”, October 2004, Birmingham, UK.

Hannus, A., Bekkering, H, Drost, E., Bontjer, R., & Cornelissen, F.W. Feature detection asymmetry in the conjunction search of colour and orientation Oral presentation. 27th European Conference on Visual Perception, August 2004, Budapest, Hungary.

Hannus, A., Bekkering, H, & Cornelissen, F.W. Not all are equal: Feature processing asymmetry in the conjunction search of colour and orientation. Oral presentation. 3 rd Annual Conference of Estonian Centre of Behavioural and Health Sciences, May 2004, Võru, Estonia.

Hannus, A., Cornelissen, F.W., & Bekkering, H. Action related intentional effects in a visual search task. Poster presentation. 9 th Annual Conference of Dutch Psychonomics Society, December, 2003, Egmond aan Zee, Netherlands.

Hannus, A., Cornelissen, F.W., & Bekkering, H. Action related intentional effects in a visual search task. Poster presentation. 26th European Conference on Visual Perception, September 2003, Paris, France.

Hannus, A., Cornelissen, F.W., & Bekkering, H. Action related intentional effects in visual search. Oral presentation. 2nd Annual Conference of Estonian Centre of Behavioural and Health Sciences, June 2003, Pühajärve, Estonia.

Hannus, A. Cornelissen, F.W., & Bekkering, H. Effects of action intention on visual perception”. Oral presentation. NeuroNord Conference 2002: Cognitive and Emotional Neuroscience. December 2002, Hanse Institute of Advanced Study, Delmenhorst, Germany.


Occupation after leaving the graduate school (if applicable): Research assistant at the University of Tartu, Estonia.


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Dipl.-Phys. Stephan Heise, Carl von Ossietzky Universität Oldenburg

Spectral and temporal effects in modulation perception

Thesis supervisor: J. Verhey, AG Neurosensorik

The amplitude of many sounds in everyday life changes over time, and it seems reasonable to assume that the patterns of these changes are used by the auditory system to analyze the acoustic environment. Yet the processing of those amplitude modulations (AMs) by the auditory system is far from fully understood.

An important question in this context is to what extent the sensitivity of our ears to AMs is due to temporal or spectral cues, respectively. I want to investigate this issue by making use of an often observed periodicity in the hearing threshold, usually referred to as the hearing threshold fine structure. If AMs are processed spectrally, then the modulation detection threshold of a sinusoidally amplitude modulated sinusoid should depend on whether the carrier frequency is placed in a fine structure minimum and the spectral sidebands fall into a fine structure maximum or vice versa. In order to perform these experiments, first of all the fine structure has to be measured, which is usually time consuming if classical procedures are used. I am currently evaluating several screening strategies together with Dr. M. Mauermann from the medical group, with the goal to find a method that is reliable but also time-efficient in order to be suitable for clinical use.

In a second project I want to examine how the envelope of an amplitude modulated signal is extracted. Measurements of the modulation detection thresholds of a test modulation in the presence of a complex masker modulation which consists of two spectral components beating at the test modulation frequency fTM reveal a dependency of these thresholds on the relative phase ϕ between test modulation and beating component. The left panel of the figure shows own results which in general agree with recent data in the literature (e.g. Verhey et al., 2003). Thresholds for the

Figure: Detection thresholds of a 30-Hz test modulation in the presence of a complex masker modulation as a function of the signal phase different subjects as indicated by different symbols and line styles. The carrier was a 5-kHz sinusoid presented at 70 dB SPL. Left: The masker modulation consisted of two components (fMM1 = 90 Hz and fMM2 = 120 Hz) beating at 30 Hz. Right: The masker modulation consisted of three components with fMM1 – fMM2 – fMM3 = 30 Hz. Horizontal lines indicate modulation detection thresholds without a masker modulation.


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in-phase condition (ϕ = 0°) are about 15 dB lower than for the out-of-phase condition (ϕ = 180°). The data clearly demonstrate that the stage responsible for envelope extraction is nonlinear, producing a distortion product at the difference frequency of the masker modulations (which equals fTM). Verhey et al. (JASA 114, 2003) tested several nonlinear mechanisms to describe the presented results, the one fitting their data best being an extraction of the envelope of the envelope (referred to as venelope). In order to investigate this further, a similar experiment is being carried out. Preliminary results, shown in the right panel of the figure, indicate a phase dependency that resembles the one in the previous experiment. Here however, the masker modulation consisted of three components, none of which beat at fTM, but whose difference frequency fMM1 – fMM2 – fMM3 was set to fTM. Despite the similar phase effect, none of the nonlinearities tested by Verhey et al. produce a component at fTM, which is large enough to explain these results. This may indicate that a different type of nonlinearity may be responsible for the processing of higher order AMs. The aim of this project is to find a model for the extraction of a signal's envelope which can explain all data consistently.

Thesis period: started March 2005

Cooperation with and/or relation to other projects: Cooperation with dissertation projects M. Buschermöhle Collaboration and discussions in seminars and group meetings with the members of

the Medical Physics group (Oldenburg, Germany) who work on measurements and modeling of the auditory system.

Exchange with Stefan Strahl on spectro-temporal filters found by an information theoretic approach.


Attended lectures: SS 2005: Lectures „Einführung in die Medizinische Physik“ and „Physikalische,

technische und medizinische Akustik“, and seminar „Neurokognition“ at the University of Oldenburg

List of attended courses: 03/2005:Winterschool of the „Deutsche Gesellschaft für Medizinische Physik“ on

„Medizinische Akustik und Audiologie“, Pichl, Austria Seminars of the InterGK in Groningen and Oldenburg Seminars of the medical physics group at the University of Oldenburg Seminars of the acoustic group at the University of Oldenburg


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Dr. Dirk Junius, Carl von Ossietzky Universität Oldenburg

Temporal and spatial aspects hearing as revealed by auditory evoked potentials


In this dissertation project the influence of realistic spatial acoustic stimuli on the generation of auditory evoked potentials (AEPs) was investigated. An optimized chirp stimulus was used, yielding responses with an improved signal-to-noise ratio compared to a click. The hypothesis of an “externalization detector” and a “localization detector”, providing enhanced and distinct neural activation for realistic combinations of ITD and ILD across frequency, was tested at various levels of the auditory pathway.

In the first part of the project, some fundamental (monaural) properties of the chirp were elucidated. Responses to long-duration stimuli with embedded chirps and responses obtained with single chirps were virtually indistinguishable for levels up to about 40 dB HL. For these conditions, the across-frequency integration of neural activity does not depend on the acoustic context and behaves linearly. At higher stimulation levels (50 dB HL and above), differences between the responses obtained in the two stimulation paradigms occurred and are probably caused by effects of neural saturation. Furthermore, with regard to temporal processing, the influence of the within-train repetition rate on wave-V latency and amplitude was examined for the click and the chirp. While wave-V latency increased with the temporal position in the train for all within-train rates (47.6, 95.2, 250 Hz), wave-V amplitude was only affected at the highest within-train rate tested (250 Hz). Wave-V latency therefore probably reflects a more sensitive indicator of neural synchronization than wave-V amplitude. The experimental results demonstrate the importance of cochlear processing for the formation of ABRs, with interesting implications for clinical applications: For studies evaluating wave-V amplitude, the stimulus-train paradigm allows higher mean stimulus rates than the traditional single-stimulus paradigm. The findings not only provide constraints on future models of peripheral and brainstem processing, but also emphasize the advantage of the chirp over the click for the follow-up chapters.

The following parts of the dissertation project investigated the dependence of chirp-evoked multi-channel AEPs on the spatial location of a sound source. A sound presentation with virtual acoustics, based on individual head related impulse responses (HRIRs), provided realistic, externalized auditory objects that varied in both azimuth and elevation. The second part focused on ABRs and middle latency responses (MLRs), corresponding to neural generators in the brainstem and primary auditory cortices, respectively. Both binaural potentials and binaural difference potentials (BDs) were examined. Response amplitudes did not benefit from using the externalized stimuli when compared to the diotic reference stimulus. For the ABR, the experimental findings showed a prominent dependence on stimulus laterality, i.e., the azimuthal distance from the midsagittal plane. This effect was prominent in binaural potentials, BDs, and the moment trajectories of a single rotating dipole that served as a source model. The sound elevation did not affect the ABRs. For the MLRs, stimulus laterality was only reflected in the latencies of the BDs. The source analysis of two


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fixed dipoles exhibited a greater activation of the dipole contralateral to the azimuthal position of the sound source compared to the ipsilateral dipole. With respect to elevational cues, the MLR right dipole source showed a slightly stronger activation for stimuli off the horizontal plane.

The third part of the project extended the experimental findings of the preceding part highlighting the binaural processes at more central stages of the auditory pathway. Late auditory evoked potentials (LAEPs) were recorded in response to a subset of stimulus conditions used in the second part. The classical oddball paradigm was used, in which a frequent standard from the front was randomly substituted by five rare deviants with other sound locations. The analysis of LAEP components and dipolar sources revealed a strong influence of the stimulus laterality. Varying the elevation of the sound did not exhibit any systematic effects. By subtracting the response to the standard from the responses to the deviants, differences curves (DCs) according to the mismatch negativity (MMN) paradigm were obtained. Amplitudes, latencies, and dipolar sources of the MMN components showed a dependence on stimulus azimuth, but not on elevation.

Overall, the results of the parts two and three indicate that sound azimuth is encoded at all levels of the auditory pathway up to the generators producing the LAEPs and the MMN components. Influences of sound elevation are only weakly and not systematically reflected in the MLRs evoked by transient stimuli such as the chirp. Since in the second part the response amplitudes to externalized stimuli are not higher than those to the diotic stimulus and in the last two parts no systematic influence of sound elevation on the potentials was found, the hypothesis of a specific “externalization detector” or “localization detector”, integrating neural activity for realistic combinations of ITD, ILD, and spectral cues, must be rejected for the investigated stages of the auditory pathway. This fact suggests that the integration of interaural and spectral cues might take place at levels subsequent to the sources generating the LAEP and MMN components investigated here.

Thesis period: June 2000 to July 2005, Scholarship from June 2000 until May 2003

Publications and Lectures: Junius, D., Riedel H., Kollmeier, B. (2005). „Is there an externalization detector at early stages of the

auditory system? A chirp-evoked auditory evoked potential study“, Hearing Research, submitted Junius, D. and Dau, T. (2005). „Influence of cochlear traveling wave and neural adaptation on auditory

brainstem responses“, Hearing Research, in press Junius, D., Riedel H., Kollmeier, B. (2003). „Binaural auditory evoked potentials with virtual acoustics”,

In Proceedings of the International Conference on Auditory Cortex, Magdeburg, p58. Junius, D., Riedel, H. Kollmeier, B. (2003): “Binaural auditory evoked potentials with virtual acoustics”,

Assoc Res Otolaryngol Abs 26 (abstract 162): p42

Publications in preparation: Junius, D., Riedel H., Kollmeier, B. (2005). „Influence of spatial position on chirp-evoked potentials:

Test of the localization detector hypothesis at central auditory processing stages“, in preparation for Hearing Research

Cooperation with and/or relation to other projects: Cooperation with dissertation projects J. Maier (Localization), R. Beutelmann (binaural interaction)

Collaboration and discussions in seminars and group meetings with the members of the Medical Physics group (Oldenburg, Germany) who work on measurements and modeling of the auditory system.


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Participation in the study program (attended lectures, courses and conferences): Regular participation in the weekly seminar of the graduate school Regular participation in the monthly meetings with the Groningen group 09/2003: Summer school “Parallels in visual and auditory processing”, Oodorn, NL 08/2004: Summer school “Object formation in audition and vision”, Bad Zwischenahn 05/2005: Mini-Symposium “Cochlea Modeling”, Oldenburg

Teaching/supervision/ counseling within the graduate school: 09/2002: Block course “Neurosensory Sciences”, supervisor of the project

“Frequency specific binaural interaction” 09/2003: Block course “Neurosensory Sciences”, supervisor of the project “Binaural

gap detection”

List of stays abroad: Regular meetings with the Groningen groups


Occupation after leaving the graduate school (if applicable): Scientist and Engineer in Audiology, Siemens Audiologische Technik, Erlangen, Germany


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Dr. Michael Kleinschmidt, Carl von Ossietzky Universität Oldenburg

Robust speech recognition based on spectro-temporal processing


In this thesis, novelle spectro-temporal feature extraction techniques are evaluated for enhancing the robustness of automatic speech recognition systems (ASR) in adverse acoustical conditions. Recent physiological and psychoacoustical findings indicate that spectro-temporal processing plays an important role in human speech perception. Therefore, sigma-pi cells and Gabor filter functions are investigated as secondary feature extraction methods based on spectro-temporal representation. Especially the Gabor features are versatile enough to include cepstral features and purely temporal filtering as special cases, while additionally aiming at combined spectro-temporal modulations. A data driven feature selection method is applied for feature set optimization. For small vocabularies, both types of features are shown to increase the robustness of ASR systems. Sigma-pi cells also allow for estimating the speech-to-noise ratio of an input signal solely based on low spectro-temporal modulation. The Gabor based Tandem feature sets increase the performance of the Qualcomm-ICSI-OGI system for the Aurora task, when concatenating the two streams.

Thesis can be downloaded at:

http://docserver.bis.uni-oldenburg.de/publikationen/dissertation/2002/klerob02/klerob02.html)

Thesis period: April 1999 to September 2002

Publications and lectures: Kleinschmidt, M., Hohmann, V.; 2003, Sub-band SNR estimation using auditory feature processing.

Speech Communication, 39(1-2), p. 47-64. Kleinschmidt, M.; 2002 Methods for Capturing Spectro-Temporal Modulations in Automatic Speech

Recognition. Acustica united with acta acustica, 88(3), p. 416-422. Kleinschmidt, M., Tchorz, J., Kollmeier, B.; 2001 Combining Speech Enhancement and Auditory

Feature Extraction for Robust Speech Recognition. Speech Communication, 34(1-2: Special Issue on Robust ASR), p. 75-91.

Kleinschmidt, M.; 2002 Spectro-temporal Gabor features as a front end for automatic speech recognition. In 3rd European Congress on Acoustics - Forum Acusticum 2002, editors: Calvo-Manzano, Perez -Lopez, Santiago, Sociedad Espanola de Acustica, p. CD-ROM, 6 pages.

Kleinschmidt, M., Gelbart, D.; 2002 Improving Word Accuracy with Gabor Feature Extraction. In International Conference on Speech and Language Processing (ICSLP), p. 4.

Kleinschmidt, M., Hohmann, V.; 2000 Perzeptive Vorverarbeitung und automatische Selektion sekundärer Merkmale zur robusten Spracherkennung. In Fortschritte der Akustik - DAGA 2000, editor: Sill, DEGA e. V., Oldenburg, p. 382-383.

Kleinschmidt, M., Marzinzik, M., Kollmeier, B.; 1998 Combining monaural noise reduction algorithms and perceptive preprocessing for robust speech recognition. In Psychophysics, Physiology, and Models of Hearing, editors: Dau, Hohmann, Kollmeier, World Scientific, Singapore, Oldenburg, p. 267-270.

Kleinschmidt, M., Tchorz, J., Wittkop, T., Hohmann, V., Kollmeier, B.; 1998 Robuste Spracherkennung durch binaurale Richtungsfilterung und gehörgerechte Vorverarbeitung. In Fortschritte der Akustik - DAGA 1998, editor: Sill, DEGA eV, Oldenburg, p. 396-397.


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Cooperation with and/or relation to other projects: Cooperation with dissertation projects J.Nix (noise reduction), R. Beutelmann

(speech perception) Collaboration and discussions in seminars and group meetings with the members of

the Medical Physics group (Oldenburg, Germany) and the Duifhuis group (Groningen) with respect to robust speech recognition

Participation in the study program (attended Lectures, courses and conferences): Regular participation in the weekly seminar of the graduate school Regular participation in the monthly meetings with the Groningen group Organization of the InterGK workshop on Dec. 9th, 2002 on “Spectro-temporal

features - Physiology, Psychoacoustics and Applications”

List of stays abroad: Oct. 2001- March 2002, International Computer Science Institute, Berkeley, CA


Occupation after leaving the graduate school (if applicable): Postdoctoral scientist, Universität Oldenburg (until 30.9.2003) DFG Geschäftsstelle, Bonn (since 1.10.2003)


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Dipl.-Biol. Karin B. Klink, Carl von Ossietzky Universität Oldenburg

The role of inhibition in auditory processing of the mouse

Thesis supervisor: Prof. Dr. Klump, Zoophysiologie & Verhalten

Various laboratory strains of the house mouse (Mus musculus) have developed into model organisms for the study of auditory processing. The availability of mutant mouse strains in combination with the knowledge of the mouse genome offers the possibility to study the genetic basis of the mechanisms underlying hearing. The aim of my project is to analyse the influence of inhibition on auditory perception in mice. Inhibition plays a major role in the processing of auditory stimuli in the vertebrate brain. Through a complex interaction of inhibition and excitation, nerve cells are able to "sharpen" their response to acoustical stimuli, therefore the reduction or increase of inhibition should be seen in the neural or behavioral response to specific stimuli. One way to study the role of inhibition is by using pharmacological manipulation (e.g. applying the glycine antagonist strychnine).

The first step in this research was to establish a suitable psychoacoustical testing method for mice. Using operant conditioning (Go/NoGo paradigm) with food rewards, the subjects’ performance in a tone detection task employing an adaptive-tracking and a constant-stimuli procedure was compared. The animals (mice of the NMRI strain) had lower and less variable thresholds using the constant-stimuli procedure than using the adaptive-tracking procedure (Klink, Bendig & Klump, in press), therefore the constant-stimuli procedure could be established as the procedure of choice for further experiments.

The constant-stimuli procedure was then applied to a duration discrimination task in which the NMRI mice were trained to report an increase in duration of a tone signal for three different reference durations (50 ms, 100 ms, 200 ms). The subjects showed an increased performance with longer reference durations; the avarage Weber fractions of the threshold ranging from 1.18 and 1.23 to 0.97, respectively (Klink & Klump, 2004, J. Comp. Physiol. A 190, 1039ff). When testing the animals using pharmacological manipulation with strychnine, there was no significant difference between subjects manipulated with strychnine and control animals (Klink & Klump, 2005, ARO abstract, p. 255). It seems that glycinergic inhibition does not play an important role in duration discrimination in mice. The performance of the subjects can be explained by using solely excitatory processes similar to those seen in long-pass neurons of the mouse inferior colliculus (Brand et al, 2000, J. Neurophysiol. 84, 1790ff).

The role of inhibition can also be seen in comodulation masking release (CMR) experiments. In these experiments, the detection of a tone in two narrowband noise maskers can be improved if the envelopes of both maskers are correlated across frequencies. CMR is attributed to synchronous auditory processing across different auditory channels; synchronous firing seems to be mediated by inhibitory interneurons which are coupled by gap juctions (e.g. Buhl et al., 2003, J. Neurosci. 23, 1013ff). The release from masking has already been shown in neuronal populations of the ventral and dorsal cochlear nucleus (e.g. Neuert et al., 2004, J. Neurosci. 24, 5789ff; Pressnitzer et al., 2001, J. Neurosci. 21, 6377ff). A simple neural circuit involving wideband inhibition of narrowband units seems to be the basis


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of the physiological mechanism underlying across-channel processes. Using an experimental paradigm applied by Schooeneveldt and Moore (e.g. 1987, JASA 82, 1944ff), the amount of masking release within and across auditory channels can be studied. Furthermore, the role of inhibition on across-channel processing can also be tested by using knock-out animals showing a reduced synchrony across different auditory channels.

Thesis period: 01.06.2002 – 31.12.2005 (projected)

Publications and lectures: Klink, K.B., Bendig, G., Klump, G.M. (2003). “Methods for mouse psychoacoustics”, in: Elsner N.,

Zimmermann, H. (Eds.), The Neurosciences from basic research to therapy - Proceedings of the 29th Göttingen Neurobiology Conference and the 5th Meeting of the German Neuroscience Society, Thieme, p. 460

Klink, K.B., Bendig, G., Klump, G.M. (2004). “Operant methods for mouse psychoacoustics”, in: Abstracts of the the twenty-seventh annual midwinter research meeting of the Assiociation for Research in Otolaryngology, volume 27, p. 104

Klink, K.B., Bendig, G., Klump, G.M. (in press). “Operant methods for mouse psychoacoustics”, Behavior Research Methods, Instruments, & Computers - Manuscript ID BR-Org-04-028

Klink, K.B., Klump, G.M. (2004). “Duration discrimination in the mouse (Mus musculus)”, Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology 190, pp. 1039 – 1046

Klink, K., Klump, G. (2005). “Duration discrimination in the mouse (Mus musclulus)”, in: Abstracts of the twenty-eighth annual midwinter research meeting of the Assiociation for Research in Otolaryngology, volume 28, p. 255

Weik, V., Klink, K.B., Klump, G.M. (2005). “Comodulation masking release in the house mouse (Mus musculus)”, in: Elsner N., Zimmermann, H. (Eds.), Proceedings of the 30th Göttingen Neurobiology Conference and the 6th Meeting of the German Neuroscience Society, p. 101B

Lectures: 02/2004 Klink: „Discrimination of duration” (06.02.04)

Cooperation with and/or relation to other projects: Cooperation with the PhD project of Marc Nitschmann on modeling inattention in

mice. Exchange of experimental methods and software development amongst other psychoacoustics projects (Julia Maier, Melanie Zokoll).

Participation in the study program (attended lectures, courses and conferences): Lecture “Physiologie des Hörsystems”, 2003, University of Oldenburg Lecture “Physikalische Akustik”, 2004/05, FH Oldenburg Regularly: Seminar of the international graduate school „Neurosensory science and

systems“, Oldenburg, Germany and Groningen, Netherlands Regularly: Seminar of the zoophysiology and behavior group, Oldenburg, Germany Non regularly: Neurobiological seminar of the institute of biology and environmental

sciences, Oldenburg, Germany 06/2003: 29th Göttingen Neurobiology conference, Göttingen, Germany 09/2003: BCN EGK Summerschool „Parallels in visual and auditory processing”,

Odoorn, Netherlands (poster presented) 09/2003: Blockpraktikum „Psychophysik und Neurosensorik”, Oldenburg, Germany 02/2004: 27th annual midwinter research meeting of the Assiociation for Research in

Otolaryngology, Daytona Beach, Florida, USA 06/2004: Meeting with the Tübinger GKKN, Tübingen, Germany 03/2005: Meeting with the Tübinger GKKN, Oldenburg, Germany (poster presented) 08/2005: Summerschool „Object formation in audition and vision: Bottom-up and top-

down processes”, Bad Zwischenahn, Germany (Poster presented)


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02/2005: 28th annual midwinter research meeting of the Assiociation for Research in Otolaryngology, New Orleans, Louisiana, USA

Teaching/supervision/ counseling within the graduate school: Supervision of the diploma thesis of Garnet Bendig (2002-2003) and Verena Weik

(2004) on mouse psychoacoustics Supervision of the practical course “Tierphysiologie“ (2002)

List of stays abroad: Bimonthly: Seminar of the international graduate school „Neurosensory science and

systems“ in Groningen, Netherlands 09/2003: BCN EGK Summerschool „Parallels in visual and auditory processing”,

Odoorn, Netherlands (poster presented) 02/2004: 27th annual midwinter research meeting of the Assiociation for Research in

Otolaryngology, Daytona Beach, Florida, USA 02/2005: 28th annual midwinter research meeting of the Assiociation for Research in

Otolaryngology, New Orleans, Louisiana, USA



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Dipl.-Phys. Kai Krajsek, Carl von Ossietzky Universität Oldenburg

Classification of the neuronal response to complex acoustic signals

Thesis supervisor: Prof. Ulrike Feudel, ICBM, Theoretische Physik/Komplexe Systeme

The aim of this project was to find a classification of the neuronal responses to complex acoustic input signals measured in starlings by the zoophysiology group (Prof. G. Klump) at the University of Oldenburg. Kai Krajsek started to analyse the neuronal signals from the extracellular recordings to identify the spike trains from different neurons. This spike sorting was the necessary first step to prepare the data for applying complexity measures from information theory in order to distinguish neuronal responses of different complexity. During this analysis it turned out that the signal-to-noise ratio of the considered data was too low to perform a reliable spike sorting. Since Kaj Krajsek left the University of Oldenburg after a short time to start a PhD in some other area of science, this project has not been finished. Michael Buschermöhle has then continued this project with a slightly different objective (see the report by Michael Buschermöhle).

Thesis period: 1.8.03-15.12.03 The project has been started in August 2003. Kaj Krajsek left the EuroGK in December 2003. He found a fully paid position (BAT IIa) in the Institute of Informatics at the University of Frankfurt (Main) and preferred to work on his PhD in this field.

Cooperation with and/or relation to other projects: Analysis of the extracellular recordings by the group of G. Klump at the University of Oldenburg

Participation in the study program (attended lectures, courses and conferences): 09/2003: BCN EGK Summerschool „Parallels in visual and auditory processing”,

Odoorn, Netherlands (poster presented) 09/2003: Blockpraktikum „Psychophysik und Neurosensorik”, Oldenburg, Germany


Occupation after leaving the graduate school (if applicable): PhD position at the University of Frankfurt (Main) in the Institute of Informatics


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Ir. Cris Lanting, Rijksuniversiteit Groningen

fMRI correlates of tinnitus

Thesis supervisor: Prof. Dr. Pim van Dijk, Dept. of Otorhinolaryngology, University Medical Center Groningen.

Tinnitus is an auditory phantom sensation (ringing of the ears) experienced when no external sound is present. Many people have experienced such a sensation for example after listening to loud music. However in 5-15 % of the general population the tinnitus is persistent. In 1-3 % of the population the tinnitus sensation is sufficiently loud to affect the quality of life.

The aim of this project is to get insight in the origin of tinnitus using functional MRI (fMRI) and if it is possible to use fMRI to quantify tinnitus using objective measures.

The project is divided into several parts:

1. The areas of interest are the auditory nuclei in the brainstem and midbrain. This is a difficult area to image with MRI because of susceptibility artefacts and movement artefacts. The susceptibility artefact is due to air-tissue boundaries at cavities. Movement of the brainstem can be explained by the basilar and vertebral arteries, which are located adjacent to the brainstem. Pulsatile movement of these arteries can cause the brainstem to move periodically. A second cause can be found in CSF fluid moving from the third to the fourth ventricle next to the brainstem. This might also be correlated to the beating of the heart.

The first step is to measure the motion of the brainstem by applying a magnetic grid, which modulates the amplitude of the underlying tissue. Movement now causes deformation of this grid, which can be tracked in time. This sequence is triggered on the heartbeat either by using ECG electrodes or a peripheral pulse unit connected to one digit of the hand. At each RR-wave a trigger is received after which a grid is applied. Right after this, 15-25 images are acquired during one heartbeat.

The analysis method is essentially developed for measurements of movement of the heart but can easily implemented using the brainstem as input. By applying a grid, each material-point receives a certain phase. By now tracking this phase in time, the motion can be calculated.

2. The second step is to determine –based on the amplitude of the movement- if it is necessary to correct for this motion by gating the acquisition of the images based on the heartbeat. Pilot measurements both with and without cardiac triggering have been performed.

3. The first functional MR imaging study involves subjects with unilateral tinnitus. Using dynamic ripples the asymmetry in the auditory brainstem is investigated to localise the affected nuclei. fMRI experiments are being prepared

4. A second study involves the “residual inhibition” which is the (temporarily) masking of the tinnitus percept by sound. fMRI experiments are being prepared

References: Axel et al (1989). MR imaging of motion with spatial modulation of magnetization. Radiology (171)

841-845


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Osman et al (2000). Imaging heart motion using harmonic phase MRI. IEEE Trans Med Imaging (19) 186-202

Osman et al (2000). Visualizing myocardial function using HARP MRI. Phys Med Biol (45) 1665-1682. Langers et al (2003). Spectrotemporal features of the auditory cortex: the activation in response to

dynamic ripples. Neuroimage (20) 265-275

Thesis period: Graduation started 06-2005 and will be finished in 05-2009

Participation in the study program (attended Lectures, courses and conferences): Every 2 weeks: BCN Journal Club July 4, 2005 InterGK Meeting: “Neurosensory Information Processing:

Phenomena and Models”. August 29, 2005 Lecture Alex Nimmerjahn : “imaging of single cells in the brain of

living and free moving animals”. September 6, 2005 Masterclass Peter Dallos



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Dipl.-Biol. Julia Maier, Carl von Ossietzky Universität Oldenburg

Mechanisms of sound localization in the Mongolian Gerbil (Meriones unguiculatus)

Thesis supervisor: G. Klump, Zoophysiologie und Verhalten

The localization of azimuth sound sources in the low frequency range is primarily based upon interaural time differences (ITD) in the sound reaching the ears (Rayleigh 1907). The prevailing view concerning how ITDs are processed in the auditory system is that neurons sensitive to ITDs code the azimuthal position of a sound source by their maximal discharge rate (Jeffress 1948). These neurons respond maximally within the physiologically-relevant range of ITDs that results from the physical dimensions of the head. However, recent investigations of ITD processing (Brand et al., 2002) in the medial superior olive (MSO) of the Mongolian gerbil suggest an alternative model of ITD coding. Brand et al. discovered that the ITDs to which neurons in the MSO respond maximally lie beyond the physiological range. Within the physiological range, the neurons' response functions show steep slopes. This is consistent with different ITDs being represented in the form of a rate code, rather than by different neurons responding maximally to a specific ITD. The ITD tuning is assumed to be mediated by prominent glycinergic inhibitory inputs onto the somata of MSO-neurons. Because of the central role of the MSO I am studying behavioral sound localization in a normal and a modified circuit. In a 2AFC paradigm with food rewards, I test the accuracy of sound localization of the Mongolian gerbil, a species with well-developed low-frequency hearing (thresholds are similar to those of humans in the range from 1 to 10 kHz, see Ryan, 1976). Their task is to report if stimuli are presented to them from the left or the right side by choosing the appropriate direction in a y-maze. Stimuli are broad-band noise as well as tones and narrow-band noise of several frequencies.

A major goal of my work was to determine the accuracy of azimuth sound localization in normal gerbils, which can distinguish between sound sources separated by 22° (Maier & Klump, submitted). In order to examine the mechanisms of sound localization in gerbils, I will carry out additional experiments in modified systems using three approaches. First, I plan to conduct experiments similar to those conducted by Maier & Klump (submitted) using elderly animals as subjects. Age related changes in the auditory pathway are known to result in severe damage to the medial nucleus of the trapezoid body (Gleich & Strutz 2001), which provides inhibitory input to MSO neurons. Preliminary data from a three-year-old animal show decreased accuracy of sound localization compared to younger controls. Second, I intend to apply strychnine, the antagonist of the inhibitory transmitter glycine, which seems to play a crucial role in binaural computation (Brand et al. 2002). Finally I am examining sound localization in gerbils reared in an omnidirectional sound field consisting of white noise. This treatment alters the arrangement of inhibitory glycinergic synapses on the soma of MSO neurons (Kapfer et al. 2002). The distribution of these inputs over soma and dendrites, rather than restricted simply to the soma, is hypothesized to reduce the ability to localize sound sources. To study further the neurophysiological basis of sound localization, I intend to spend a six month period in the Spatial Hearing Laboratory, headed by Prof. David McAlpine, at University College London.


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References: Brand, A., Behrend, O., Marquardt, T., McAlpine, D., Grothe, B. (2002): Precise inhibition is essential

for microsecond interaural time difference coding. Nature 417, 543-547. Gleich, O., Strutz, J. (2002): Age dependent changes in the medial nucleus of the trapezoid body in

gerbils. Hear. Res. 164, 166-178. Jeffress, L. A. (1948): A place theory of sound localization. J. Comp. Physiol. Psychol. 41, 35-39. Maier, J., Klump, G. (in review): „Accuracy of azimuth sound localization in the Mongolian gerbil

(Meriones unguiculatus)“, JASA Kapfer, C., Seidl, A., Schweizer, H., Grothe, B. (2002): Experience-dependent refinement of inhibitory

inputs to auditory coincidence-detector neurons. Nature Neurosci. 5 (3), 247-253. Rayleigh, L. (1907): On our perception of sound direction. Phil.Mag. 13, 214-232. Ryan, A. (1976): Hearing sensitivity of the mongolian gerbil, Meriones unguiculatus. J. Acoust. Soc.

Am. 59 (5), 1222-1226.

Thesis period: 01.06.2004 – 31.05.2007

Publications and Lectures: 11/2004: Invited seminar at the Spatial Hearing Laboratory, University College, London, UK Maier, J., Klump, G., (2005): „Directional hearing in the gerbil. Abstr. Asoc. Res. Otolaryngol. 954, 334. Maier, J., Klump, G.: submitted. „Accuracy of azimuth sound localization in the Mongolian gerbil

(Meriones unguiculatus)“, JASA

Publications in preparation: Maier, J., Klump, G.: „Influence of rearing in omnidirectional white noise on the accuracy of azimuth

sound localization in the Mongolian gerbil (Meriones unguiculatus)“, in preparation for JASA

Cooperation with and/or relation to other projects: To investigate if the gerbils use a closed- or an open-loop mechanism for localizing sound sources, Stefan Strahl and Rainer Beutelmann developed a semi-automatic MATLAB tool for tracking the gerbils’ head orientation.

Exchange of experimental methods and software development amongst other psychoacoustics projects (Karin Klink, Melanie Zokoll)

Participation in the study program (attended lectures, courses and conferences): Physikalische Akustik, 2004/2005, FH Oldenburg Weekly: Seminar of the international graduate school “Neurosensory Science and

Systems” Weekly: Seminar of the zoophysiology and behavior group Irregularly: Neurobiological seminar of the groups molecular neurobiology,

neurobiology and zoophysiology and behavior 09/2003: Block course “Psychophysik und Neurosensorik”, Oldenburg, Germany 06/2004: Meeting with “GKKN Tübingen”, Tübingen, Germany 03/2005: Meeting with “GKKN Tübingen”, Oldenburg, Germany 08/2005: Summerschool “Object formation in audition and vision: Bottom-up and top-

down processes”, Bad Zwischenahn, Germany (poster presented) 02/2005: ARO, New Orleans, LA, USA

Teaching/supervision/ counseling within the graduate school: 10/2005: Supervision of a two-week practical course of measuring head-movements

in the gerbil

Stays abroad: 11/2004: Invited seminar at the Spatial Hearing Laboratory, University College,

London, UK 02/2005: ARO, New Orleans, LA, USA


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Dipl.-Phys. Ronny Meyer, Carl von Ossietzky Universität Oldenburg

Models for localization and separation of sound signals based on statistics of binaural and monaural signal features.

Thesis supervisor: Dr. Volker Hohmann, Prof. Dr.Dr. Birger Kollmeier, Medizinische Physik, Universität Oldenburg

The human auditory system combines several monaural and binaural features for spatial localization, identification and separation of sound signals. The auditory system takes the mixture of sound that it derives from a complex natural environment and sorts it into packages of acoustic evidence in which each package probably has arisen from a single source of sound. The aim of the dissertation is the modeling of this process by using statistical methods of sourcecoding – and separation. First work was done in my diploma thesis, in which the tracking of the fundamental frequency with stochastic methods was examined.

Thesis period: Thesis period: September 2004 – Juni 2005 (Abort because of choice of employment in industry) InterGK period: September 2004 – Dezember 2004

Publications and Lectures: R. Meyer, J. Nix, V. Hohmann, „Sequentielle Monte-Carlo-Verfahren zur Grundfrequenzerkennung

überlagerter realer und synthetischer Vokale”, Jahrestagung für Akustik DAGA 2005 (in press)

Cooperation with and/or relation to other projects: Cooperation with dissertation projects J. Nix (SMC algorithm), R. Beutelmann

(localization) Collaboration and discussions in seminars and group meetings with the members of

the Medical Physics group (Oldenburg).

Participation in the study program (attended lectures, courses and conferences): Blockpraktikum „Digital signal processing“, 2/2004, Oldenburg Summerschool "Neurosensory Science and Systems" in Bad Zwischenahn, 8/2004 Regularly: Medical Physics Seminar, Oldenburg

Teaching/supervision/ counseling within the graduate school: Training: Softskill 1.0 : Die eigene Teamkompetenz steigern (two day workshop on

teamdevelopment)


Occupation after leaving the graduate school (if applicable): Project manager for R&D projects in wind energy research, Firma ems


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Dipl.-Phys. Marc Nitschmann, Carl von Ossietzky Universität Oldenburg

Modeling inattention and across-frequency processing in binaural signal processing

Thesis supervisor: Prof. Dr. Dr. Birger Kollmeier and Jun. Prof. Dr. Jesko L. Verhey

Modeling the inattentive observer Inattentive listeners can alter the results of psychophysical experiments considerably. This problem is especially difficult to handle with when performing psychophysical experiments with animals that cannot be asked explicitly about their state of attention. To develop and test models of inattention data of mice (Mus musculus) in a tone duration discrimination experiment were used, which were collected by Karin Klink. I adapted a model by Green (1995) to her experiment and extended it assuming a changing state of attention over time. The inattention of the animal in a certain trial is estimated from a number of preceding trials using maximum likelihood estimation. Preliminary simulations indicate that attention has to be accounted for by a time varying factor rather than a constant as assumed in Green (1995).

Across-frequency processing in binaural signal processing Van de Par and Kohlrausch (1999) proposed that across-frequency integration of the information has to be considered in binaural experiments but only for narrowband maskers at the signal frequency. In contrast, across-frequency can be disregarded if the masker prevents the usage of off-frequency channels such as in the case of broadband maskers or in the notched noise experiment. Assuming that the monaural threshold is determined by the masker energy in the peripheral channel at the signal frequency the benefit of the binaural processing - i.e. the binaural masking level difference (BMLD) - should be the same for the broadband masker and the notched noise masker with the same monaural or diotic threshold. In order to test this hypothesis I measured thresholds in the notched noise experiment for different notch width and for broadband maskers with different levels in the diotic condition (N0S0) and the dichotic condition (NoS?). The figure below shows the NoS? thresholds of the notched noise experiment (triangles) and the broadband masking experiment (squares) as a function of the corresponding N0S0 thresholds. The BMLD is the vertical distance between the dashed diagonal and the respective threshold curve. The data is in contrast to the predictions of the hypothesis by van de Par and Kohlrausch since the BMLDs for the broadband and notched noise masker differ considerably especially at low N0S0 thresholds. Thus, models that assume a mechanism as in van de Par and Kohlrausch (e.g. Zerbs, 2000) fail to predict the notched noise data.

References: Green, D.M. (1995). Maximum-likelihood procedures and the inattentive observer. J. Acoust. Soc. Am.

97, 3749-3760 Van de Par, S. and Kohlrausch, A. (1999). Dependency of binaural masking level differences on

center frequency, masker bandwidth, and interaural parameters. J. Acoust. Soc. Am. 106, 1940-1947

Zerbs, C. (2000). Modelling the effective binaural signal processing in the auditory system. PhD thesis, Universität Oldenburg


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Thesis period: 01.02.2004-31.01.2007 (projected)

Cooperation with and/or relation to other projects: Cooperation with the PhD projects of Karin Klink (see above), Rainer Beutelmann & Julia Maier (binaural hearing)

Participation in the study program (attended lectures, courses and conferences): Blockpraktikum „Digital signal processing“, 2/2004, Oldenburg Blockpraktikum „Psychophysik und Neurosensorik“, 9/2004, Oldenburg Lecture „Physikalische, technische und medizinische Akustik“, 2004, Oldenburg Summerschool "Neurosensory Science and Systems" in Bad Zwischenahn, 8/2004 Regularly: Medical Physics Seminar, Oldenburg InterGk Seminar, Oldenburg Visits of the different research groups in Groningen and Oldenburg

Teaching/supervision/counseling within the graduate school: Blockpraktikum „Digital signal processing“, 2/2005, Oldenburg


Figure: Dichotic (NoSπ) thresholds as a function of the corresponding diotic (N0S0) thresholds in the notched noise (triangles) and broadband masking (squares) experiment. Diamonds indicate predicted notched noise thresholds with a model that only considers on-frequency information.


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Dr. Johannes Nix, Carl von Ossietzky Universität Oldenburg

Localization and Separation of concurrent Talkers based on Principles of Auditory Scene Analysis and multi-dimensional Statistical Methods

Thesis supervisor: Birger Kollmeier, Volker Hohmann, AG Medizinische Physik

Problem statement and approach Noise suppression for speech in nonstationary noises, as for example needed in digital hearing aids, remains a difficult challenge. So far, two lines of strategies were investigated: First, directional filtering, and second, spectral estimation. Directional filtering has shown limited success, while spectral estimation approaches failed to improve speech intelligibility in nonstationary noise. The human auditory system has far more successful strategies which also deal with underdetermined, masked, and unreliable data, including directional information. So far, quantitative models of this accomplishment do not exist. The project aimed to integrate directional filtering and statistical methods with strategies known from auditory processing of directional information, and auditory scene analysis. As basic parameters which carry directional information, interaural parameters, namely interaural phase and level differences, were used.

Parts of the project: Methods and results The project was divided in three parts: The first investigated the influence of real world noise environments on interaural parameters and whether a statistical description of these parameters is sufficient to explain sound localization in noise. For this, the statistics of interaural parameters in several environments was evaluated. Strong alterations of the parameter statistics were found for signal-to-noise ratios between -5 and 5 dB. The signal-to-noise ratio has a large impact on the parameter statistics. In contrast, there is relatively little dependency from the noise environment.

The second part used this knowledge of parameter statistics to implement a technical usable algorithm for sound localization in noise. This statistical algorithm was tested extensively. The results show that the algorithm can localize single talkers robustly even in high levels of noise, and can partly distinguish even directions on the median plane and on the so-called „cones of confusion“. It is also able to localize several concurrent talkers precisely and robustly. Further, a frequency-domain description of statistical processing of interaural parameters can explain a surprisingly large part of the sound localization capabilities of humans. Based on the statistical estimation approach, a speech enhancement algorithm was developed, which uses directional filtering controlled according to the estimated directions to suppress specific talkers. High suppressions and little distortions were reached with low computational effort.

The third part tackles the problem of under-determinedness of the noise-disturbed, partially masked input, by including additional information on spectro-temporal dynamics of speech. To implement this new approach, a stochastic state-space model was developed. So far, such models have not been treatable because of their enormous complexity and the combination of nonlinear and stochastic properties. An extensive search on statistical methods showed up recently developed approaches, so-called „Sequential Monte Carlo Methods“, which allow to realize very complex estimation tasks, and go along with current hypotheses on neural processing. Based on these methods, a novel on-line algorithm which performs talker localization and


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voice separation based on spectro-temporal and directional features was implemented. It was shown that this concept is able to separate voices under commonly used conditions, with excellent localization accuracy and with extremely small convergence times. Moreover, the flexibility of the approach allows to incorporate further aspects of scene analysis, and statistical knowledge about sound sources into noise reduction algorithms.

Publication of results The project was documented in a PhD thesis which is written as a collection of three research articles. The first part has been accepted for publication in the Journal of the Acoustical Society of America, the second part is being prepared to be published in the same journa l, and the third part has been submitted to a special issue of the IEEE Transactions on Speech and Audio Processing. As citations of conference contributions, e.g. by Gandhi and Hasegawa-Johnson (ICSLP 2004), or Rennie, Achan, Frey, and Aarabi (Aistats 2005) show, the results are picked up and stimulate similar research in the field. Further research on statistical methods and scene analysis is planned in collaboration with researchers working on signal processing, auditory models, and neurobiology.

Thesis period: 04/1999 – 05/2005; Date of defense: 07/2005; Time of scholarship 03/1999 -12/2001

Publications and Lectures: Meyer, R. Nix, J. and Hohmann, V. (2005) „Sequentielle Monte-Carlo-Verfahren zur

Grundfrequenzerkennung überlagerter realer und synthetischer Vokale“, Proc. DAGA 2005 Nix, J., Hohmann, V. (2005) „Sound source localization in real sound fields based on empirical

statistics of interaural parameters“, Journal of the Acoustical Society of America (accepted for publication)

Nix, J., Kleinschmidt, M. and Hohmann, V., (2003) „Computational auditory scene analysis by using statistics of high-dimensional speech dynamics and sound source direction“, Proc. Eurospeech, 1441-1444

Nix, J., Kleinschmidt, M., Hohmann, V. (2003) „Computational scene analysis of cocktail-party situations based on sequential Monte Carlo methods“, Proc. of the Thirty-Seventh Asilomar Conference on Signals, Systems, & Computers (1), 735 -739

Hohmann, V. ,Nix, J., Grimm, G., Wittkop, T., (2002) „Cocktail party processing based on interaural parameters“, Acta acustica united with acustica 88, 1-6

Nix J., Hohmann V. (2001) „Verallgemeinerbarkeit von Referenzen in einem Lokalisationsmodell und Auswirkungen auf Robustheit und Generalisierungsvermögen“, Proc. DAGA 2001

Nix, J. and Hohmann, V., (2000) „Robuste Lokalisation im Störgeräusch auf der Basis statistischer Referenzen“, Proc. DAGA 2000, 384-385

Nix, J. and Hohmann, V. (2001) „Enhancing sound sources by use of spatial cues“, Proc. of the Eurospeech 2001 Workshop on Consistent and Reliable Acoustical Cues (CRAC), 1-4

Nix, J. and Hohmann, V. (1999) „Statistics of binaural parameters and localization in Noise“, in: „Psychophysics, Physiology and Models of Hearing“ (Dau., T., Hohmann, V. Kollmeier, Eds.), 263-266

Hohmann, V., Albani, S. Nix, J. (1999) Application of localization models to noise suppression in hearing aids, ACUSTICA - acta acustica 85, S225

Publications in preparation: Nix, J., Hohmann, V. (2006) „Combined estimation of spectral envelopes and sound source direction

of concurrent voices by multidimensional statistical filtering“, submitted to the IEEE Transactions on Speech and Audio Processing

Nix, J., Hohmann, V., Kollmeier, B. „Application of noise-robust binaural sound localization for the identification and the seperation of concurrent voices“, in preparation for the Journal of the Acoustical Society of America

Cooperation with and/or relation to other projects: Part of the work was done in collaboration with the Ph.D. projects „Robust speech recognition based on spectro-temporal processing“ (M. Kleinschmidt) and „Across-


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frequency processing in convolutive blind source separation“ (J. Anemüller) and with the project R. Meyer.

Teaching/supervision/ counseling within the graduate school: J. Nix participated in the supervision of the diploma thesis of Dirk Siemer (Evaluation of beamforming methods for hearing aids) and Ronny Meyer (Application of Sequential Monte Carlo Methods to tracking formant frequencies of concurrent voices). Further, he participated in teaching laboratory courses on digital signal processing. In collaboration with J. Anemüller and M. Kleinschmidt, Several special seminars and tutorials were given on Kalman filtering, support vector machines, and sequential Monte Carlo Methods.

List of stays abroad: International conference attendance, regular meetings of the InterGK with Groningen


Occupation after leaving the graduate school (if applicable): Research associate at the University of Oldenburg


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Dipl.-Phys. Handy Oey, Carl von Ossietzky Universität Oldenburg

Development of a model of vibration perception based on psychophysics and physiology of the somatosensory system

Thesis supervisor: Volker Mellert, Akustik

Summary Vibration perception is becoming a more important issue in different research areas with diverse objects. Investigations range from investigation of high-level whole-body vibrations in a workplace environment including health issues to low-level hand-finger vibrations as feedback for tactile displays or to improve virtual reality. Although intensively investigated almost all research is closely linked to a specific application or generic to neurology in particular focused on tactile perception.

This study investigates the perception of vibrations at two different parts of the human hand, the fingertip and the palm providing some basic psychophysical research. In combination with knowledge from the physiology of the human somato sensory system the objective is to model and broaden the view on the perception of tactile vibration.

A extensive literature research has been done to collect current knowledge about the human somatosensory system in order to provide a layout for a human response model. In addition psychophysical measurements have been made investigating the vibration threshold, equal-level vibrations and just noticeable difference in frequency for the finger tip and the palm. Three of the four mechanoreceptors can be distinguished in those psychophysical measurements and certain properties of the data can be related to the individual properties of the respective neurological mechoreceptors. Based on these results and the collated neuro-physiological data a three-receptor human response model was programmed mimicking the neurological behaviour of the somatosensory system.

Current structure of thesis • Vibration perception thresholds and equal level vibrations at the fingertip and

palm. • Just noticeable differences in frequence for vibrations at the fingertip and

palm. • Modeling the physiology of the somatosensory system • A human response model for tactile vibration based on physiology and

psychophysics.

Currently the thesis is in its final stage.

Thesis period: September 2001-3/2006, funded 09. 2001 - 09. 2004

Publications and lectures: Oey, H., (2001). „Neuvermessung der Normalkurven gleicher Pegellautstärke mit einem interleaved 2-

AFC-Verfahren“, DAGA Proceedings 2001 Oey, H., (2001). „Neuvermessung der Normalkurven gleicher Pegellautstärke mit einem interleaved 2-

AFC-Verfahren“, Diplomarbeit Oey, H., (2004). „Vibration Threshold And Equal Vibration Levels At The Human Fingertip And Palm“,

ICA Proceedings 2004,


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Oey, H., (2004)., „Modeling Mechanosensors“, InterGK seminar Objectformations in audition and vision,

Publications in preparation: Oey, H., (2005). „Development of a model of vibration perception based on psychophysics and

physiology in the somatosensory system.“, in preparation

Cooperation with and/or relation to other projects: Cooperation with

• Juniorprofessor J. Kretzberg on tactile perception and modelling • Dr. M. Bellmann (former graduate from Graduate School) on vibration

processing and experimental set-up • S. Buss (associate to Graduate School with thesis submitted) on modelling

effective signal processing in perception Continuous collaboration and discussion in seminars and group meetings with the members of the Acoustics group (Oldenburg).

Participation in the study program (attended Lectures, courses and conferences): Seminar of the InterGK, 2001-2004, Oldenburg, Germany Kolloquium zur Akustik, Medizinischen Physik und Signalverarbeitung, 2001-2004,

Oldenburg, Germany 08/2000: Internoise, Nizza, France 03/2001: DAGA 01, Hamburg Harburg, (Land) 09/2003: 38th UK Conference on Human Response to Vibration, Gosport, UK 03/2004: SFA/DAGA 2004, Strassburg, France 04/2004: ICA, Kyoto, Japan 07/2004: Summerschool: Objectformations in audition and vision, Bad Zwischenahn,

Germany

Teaching/supervision/ counseling within the graduate school: Betreuung des Fortgeschrittenen-Praktikums: Physik des Gehörs II: Maskierung



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Carlos Rizzo, Rijksuniversiteit Groningen

Spatial Distribution of the fMRI transfer function

Thesis supervisor: H. Duifhuis, Biomedical Engineering, RU Groningen

Functional magnetic resonance imaging (fMRI) is one of the techniques widely used in cognitive neuroimaging studies, these studies are based on brain activation under different kind of tasks, including the auditory response from the brain. Therefore, it is of great interest to quantify, characterise, and be able to predict the acoustical noise this machine produces and the effect of the walls, floor and ceiling inside the scanner room.

This can be done by finding the spatial distribution of the impulse transfer function H(w) of the fMRI scanner inside and outside the bore by using a pulse train stimulation in the gradient current coils of the scanner. After the acoustic noise is produced by the scanner recordings in different locations inside and outside the bore are taken using magnetically compatible microphones.

Ultimately, the calculations of the sound levels in different scales are also calculated inside and outside the bore for different frequencies.

Thesis period: 01.03.2004-01.02.2008


Dissertation projects Remken, Hoiting

Participation in the study program (attended Lectures, courses and conferences): Monthly meetings of the InterGK Inter GK Conference on Auditive Encourage and Voice Insight, 2004


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M. Sc. Bodhisatya Sarker, Carl von Ossietzky Universität Oldenburg

Design of low power hearing aid chip

Thesis supervisor: Prof. W. Nebel, Embedded Hardware Software group

The work was based on designing low power hearing aid chip. It involved various low power techniques both at the system level and the back end stage of the design.

My Scholarship was terminated after 16 months.

Thesis period: Start: July 2002, Terminated: August, 2003

Publications and Lectures: B. Sarker, M Schulte, W. Nebel, "Low Power Optimisation techniques in Overlap Add algorithm",

International Conference on Computer, Communication and ControlTechnologies (CCCT '03), Orlando, USA, July 31-Aug 2, 2003.

B. Sarker, M. Schulte, M. Hillers, W. Nebel, "Memory Power Optimisation in an Application Specific Algorithm", Dresdner Arbeitstagung Schaltungs - und Systementwurf (DASS´2003), Dresden, Pg. 25-30, May 8-9, 2003.

B. Sarker, W. Nebel, “Experimental Application of Source Code Transformations for Power Reduction in Hearing Aids”, EUROMICRO Conference, Turk ey, Sept. 2003.

S. Frimont, G. Schumacher, W. Nebel, B. Sarker “A simulation approach for the analysis of real-time systems on single processors”, EUROMICRO conference, Turkey, Sept. 2003


Occupation after leaving the graduate school (if applicable): Working in a chip design company in India.


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Ir. Rick L. M. Schoffelen, Rijksuniversiteit Groningen

The mechanical response of the tectorial membrane in the inner ear of the frog

Thesis supervisor: Prof. Dr. Pim van Dijk (UMCG, Dpt. Of Otorhinolaryncology)

Mammals and amphibians, both members of the order of vertebrates, are generally supposed to have a common ancestor. However, the evolutionary path of the different classes is not yet agreed on (Fay and Popper [1999], Wever [1985], Lewis et al. [1985]).

The ear of anuran amphibians (frogs and toads) is used in hearing research as an animal model for the mammalian ear. Many of the important features are shared, like mechano-sensitive transduction through hair cells, the tympanum, and the middle ear transmission. On the other hand, vast differences in the inner ear structure cause the mammalian cochlea either to be viewed as a more derived state of the vertebrate inner ear (Bergeijk [1957]), or an entirely different evolutionary solution to the problem of translating pressure waves into neural signals. Though, insights gained from the anuran ear about the evolution of the mammalian ear may be different depending on the outcome of this discussion, the physiological and neurobiological model provided by the anuran ear remains valuable because of both its similarities and its dissimilarities.

In my project I want to record the motion in the tectorial membrane of the both auditory end-organs in the frogs inner ear, providing insight in the way the membrane aids the haircells in detecting sound stimuli.

The recording is done using an optical microscope and a CCD camera, after which computer algorithms are used to determine motion from the images. The specific set-up we use allows us to create 3D-T-images of the membrane in motion, without any (mechanical or chemical) changes to the membrane itself. Similar measurements have been conducted at the lizard’s ear (Aranyosi [2002]).

State of the dissertation project

In the past 6 months the entire set-up needed for data-acquisition has been built, including the photo-microscope and the image-acquisition software. Also the dissection techniques for preparing the specimen have been developed and tested. We can now quickly get access to one of the auditory end-organs, the basilar papilla.

Currently the focus is very much on developing way to apply the stimulus to the specimen in a controlled way and on the processing of the images.

After these issues have been solved, the entire measurement process will be largely completed. The next step, then, will be to acquire data from the basilar papilla, followed by an effort to gain access to the other end organ, the amphibian papilla.

References A. Aranyosi. Measuring sound-induced motions of the al ligator lizard cochlea. PhD thesis,

Massachutsetts Institute of Technology, June 2002. W. Bergeijk. Observations on models of the basilar papilla of the frog’s ear. J.Acoust.Soc.Am., 29-

11:1159–1162, 1957. R. Fay and A. Popper. Comparative hearing: fish and amphibians. Springer, 1999. E. Lewis, E. Leverenz, and W. Bialek. The vertebrate inner ear. CRC Press, 1985. E. Wever. The amphibian ear. Princeton University Press, 1985.


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Thesis period: started 01-2005, planned end date 12-2008.

Cooperation with and/or relation to other projects: We do have working relationships with the research group of Dr. S.M. van Netten (Neurobiophysics, University of Groningen, Groningen, The Netherlands), and with Dr. A.J. Aranyosi (Massachusettes Institute of Technology, Boston (MIT, Mass., USA) in the field of image analysis.

Participation in the study program (attended Lectures, courses and conferences): BCN Journal Club Every two weeks 30 – May – 2005 Symposium Cochlea Modeling (Oldenburg) 04 – April – 2005 InterGK Meeting (Groningen)



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Dr. Timm Schubert, Carl von Ossietzky Universität Oldenburg

Different retinal neural networks express distinct connexins

Thesis supervisor: Prof. Dr. Reto Weiler, AG Neurobiologie

Recent investigations have brought new insight in functional implications of electrical coupling in the mouse retina. Electrical coupling is mediated by proteins of the connexin (Cx) family. Connexins are channel forming proteins that build up hexameric hemichannels in membranes of apposed cells to form intercellular gap junction channels. Each member of this connexin family has very specific biophysical properties. Therefore an identification of the connexin that mediates the coupling of a certain neuron type is essential because this pore-forming protein determines the properties of the whole network. Especially for the rod pathway, detailed knowledge of the involved connexins and their role in synaptic transmission has been achieved. In contrast, other connexins of gap junctionally coupled lateral networks (horizontal-, amacrine- and ganglion cells) have not been analyzed in detail. Horizontal cells modulate the signal transfer from the light-catching photoreceptors to bipolar cells by providing lateral inhibitory feedback to the photoreceptors. These neurons form an very extensively coupled network which points to an integration of visual signals from a large area of the retina. Synchronization of ganglion cell responses, based on electrical coupling among ganglion cells, has been favoured to provide additional information for visual signal processing in higher brain regions. However, in ganglion cells as in horizontal cells, the identity of the expressed connexins and the putative implications for the network properties remain unclear. Consequently, identification of the connexins involved in horizontal cell - and ganglion cell coupling will provide more insight and deepen the understanding of gap junction function for visual perception.

A major advantage of studying visual processes in the mouse retina is the increasing number of available transgenic mouse strains. We want to examine tracer coupling in retinae obtained from mice with modified connexin coding regions. The gap junction permeable tracer Neurobiotin will be injected in horizontal – and ganglion cells of the flattened retina and intercellular spread of Neurobiotin will be visualized with Streptavidin-Cy3. The extent of tracer diffusion through the networks can be documented with a 568 nm line in a confocal microscope.

We want to focus on three ganglion cell types (alpha-ganglion cells and two types of bistratified ganglion cells) and the horizontal cells that are known to be tracer coupled in the mouse retina. The experiments will be performed in retinae obtained from several transgenic mouse lines: The use of connexin deficient mouse lines (Cx36-/- -, Cx45fl/fl:Nestin-Cre -, and Cx57lacZ/laZ-mice) will reveal the significance of Cx36, Cx45 and Cx57 for the gap junctional coupling of the studied neuron types. Cx36+/lacZ-, Cx45+/lacZ and Cx57lacZ/lacZ mouse strains in combination with the ß-gal method will visualize the Cx36, Cx45 and Cx57 expression in the cells. Membrane insertation of Cx36 can be detected by the fusion protein Cx36-EGFP.

A major advantage of studying visual processes in the mouse retina is the increasing number of available transgenic mouse strains. We examined tracer coupling in retinae obtained from mice with modified connexin coding regions. The gap junction permeable tracer Neurobiotin was injected in horizontal – and ganglion cells of the flattened retina and intercellular spread of Neurobiotin was visualized with


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Streptavidin-Cy3. The extent of tracer diffusion through cells of the retina was documented with a 568 nm line in a confocal microscope.

We focused on horizontal cells and three ganglion cell types (alpha-ganglion cells and two types of bistratified ganglion cells) that revealed tracer coupling in the mouse retina. Whereas OFF-alpha-ganglion-cells showed tracer spread to other ganglion cells and amacrine cells, ON-alpha-ganglion-cells were only heterologously coupled. Both subtypes expressed Cx36 which was shown by using Cx36EGFP -, Cx36+/lacZ- and Cx36-/- -mouse lines. Two different types of bistratified ganglion (BSGCs) cells were found to be homologously coupled. Injections in Cx45fl/fl:Nestin-Cre retinae revealed a significantly reduced number of coupled cells. The expression of Cx45 in BSGCs was confirmed by tracer injections in Cx45+/lacZ mice in combination with ß-gal staining. Thus Cx45 plays a prominent role mediating electrical coupling of these two BSGC types. In Cx57lacZ/laZ retinae, tracer spread within the horizontal cell network was completely abolished. The presumption that Cx57 mediates horizontal cell coupling. was supported by the finding of Cx57 expression in the same mouse strain.

These data demonstrate a neuron type specific expression of different connexins. This suggests that horizontal- and ganglion cell networks which base on different connexins have distinct functional properties.

Dissertation is finished, defence was on 11.05.2005.

Thesis period: 10.1999 – 05.2005, associated member of the InterGK: 12.2000-05.2005 (travel grants)

Publications and Lectures: Schubert T., Maxeiner S., Krüger O., Willecke K. and Weiler R. (2005) “Bistratified ganglion cell

coupling is mediated by connexin45”. J. Comp. Neurol. (in press) Schubert T., Degen J., Willecke K., Hormuzdi S.G., Monyer H. and Weiler R. (2005) “Connexin36

mediates gap junctional coupling of alpha-ganglion cells in mouse retina”. J. Comp. Neurol. 485:191-201

Hombach S., Janssen-Bienhold U., Söhl G., Schubert T., Büssow H., Ott T., Weiler R. and Willecke K. (2004) “Connexin57 (Cx57) deficient mice with lacZ reporter gene reveal functional expression exclusively in horizontal cells of mouse retina”. Eur. J. Neurosci. 19: 2633-2640

Schubert T. and A. Akopian (2004) “Actin filaments regulate voltage-gated ion channels in salamander retinal ganglion cells”. Neuroscience 125: 583-590

Publications in preparation: Schubert T., Weiler R.and Feigenspan A. (2005). “Intracellular calcium is regulate by different

pathways in horizontal cells of the mouse retina“, for the Journal of Neuroscience Shelley J., Schubert T., Dedek K., and Weiler R. (2005) “Spatial Properties of Horizontal Cell

Responses in the Wildtype and Cx57-deficient Mouse Retina“, in preparation for the Journal of Neuroscience

Cooperation with and/or relation to other projects: Cooperation with dissertation projects M. Greschner, F. Schütte, Jennifer Shelley,

Mark Pottek Collaboration and discussions in seminars and group meetings with the members of

the retina neurobiology group (Oldenburg) and the vision physiology group (Groningen).

Participation in the study program (attended lectures, courses and conferences): 02/2005: Göttinger NeurobiologenTagung 09/2004: Vision Down Under meeting, Fraser Island,Australia


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09/2004: ICER meeting, Sydney, Australia 09/2003: Neuroscience meeting, New Orleans, USA 06/2003: Göttinger NeurobiologenTagung 06/2002: FASEB retina meeting, Vermont, USA 06/2002: Neuroscience meeting, Paris 07/2001: ARVO, Ft.Lauderdale, USA 06/2001: Göttinger NeurobiologenTagung

Teaching/supervision/ counseling within the graduate school: 05/06/2004 Visual Neuroscience lecture

List of stays abroad: 06/2001 stay in Dr. Abram Akopian’s lab, New York, USA 09/2003 stay in Prof Dr. Steve Massey’s lab, Houston, USA 09/2004 stay in Prof Dr. David Vaney’s lab, Brisbane, Australia 09/2005 stay in Prof Dr. Rachel O.Wong’s lab, St.Louis, USA


Occupation after leaving the graduate school (if applicable): 05-08.2005 Postdoc in Prof. Dr. Reto Weiler’s lab 08.2005-08.2007 Postdoc in Prof. Rachel O. Wong’s lab, Washington University,

USA, funded by DFG Postdoc stipend


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Dr. Frank Schütte, Neurobiologie, Carl von Ossietzky Universität Oldenburg

Identification and characterization of retinoic acid-binding proteins in the fish retina

Thesis supervisor: Apl. Prof. Dr. U. Janssen-Bienhold , Prof. Dr. R. Weiler, Neurobiology

During light adaptation the retinal light sensitivity adapts to the respective ambient light conditions. Different neuromodulators, whose synthesis or releases correlate with the ambient light conditions, mediate the underlaying processes of light adaptation. Previous studies have shown that RA mimics effects of continuous light exposure on the physiology and morphology of horizontal cells in the fish retina (Weiler et al., 1998; Pottek & Weiler, 2000). Although it was demonstrated that the uncoupling effect on horizontal cells is mediated by an external membrane-bound RA receptor-like binding site and a nongenomic pathway, the exact molecular mechanisms of this effect were still unknown (Zhang & McMahon, 2000). Thus the aim of this dissertation project was to characterize and identify at least one RA-binding protein that could be involved in the RA pathway.

To demonstrate and characterize RA-binding sites in the carp retina a binding assay was developed. In addition, a photoaffinity labeling assay (modified from Bernstein et al., 1995) was used to partially characterize RA-binding proteins. To analyze the distribution of retinoic acid receptor (RAR)-like proteins in the carp retina, an antibody was tested, that was directed against the human RAR alpha 1.

The binding assay revealed the existence of at least one high-affinity RA binding site (KD = 36 nM) in the membrane fraction of the carp retina. This binding site showed a unique pharmacology compared to other known RA-binding sites. Two anti-RARα-immunoreactive membrane-associated proteins (43 kDa and 46 kDa) were detected in horizontal cell fractions of the carp retina. RARα-immunoreactivity was primarily localized at the dendritic tips and the region in and around the nucleus of cone horizontal cells.

Proteins of a membrane fraction of the carp retina were separated by means of preparative gel electrophoresis (PGE) and subsequently subjected to a photoaffinity labeling assay. In a PGE fraction, containing the anti-RARα-immunoreactive 43 kDa protein, tritiated RA-binding by a 43 kDa protein could be demonstrated. In contrast, no RA-binding by a 46 kDa protein was detectable in a PGE fraction, containing the 46 kDa RARα-immunoreactive protein. Tritiated RA-binding by the 43 kDa protein was partially inhibited by unlabeled RA as well as by the RARα antibody. The anti-RARα-immunoreactive 43 kDa protein was therefore isolated by means of two-dimensional gel electrophoresis and identified as an enolase-like protein by mass spectroscopy (MudPIT). Since no interaction between RA and enolase has yet been described, a lot of further experiments would be necessary to proof the involvement of enolase in the RA pathway.

References: Bernstein, PS, Choi, SY, Ho, YC, Rando, RR (1995). Photoaffinity labeling of retinoic acid-binding

proteins. Proc Natl Acad Sci 92: 654-658.


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Pottek, M & Weiler, R (2000). Light -adaptive effects of retinoic acid on receptive field properties of retinal horizontal cells. Eur J Neurosci 12: 437-445.

Weiler, R, Schultz, K, Pottek, M, Tieding, S, Janssen-Bienhold, U (1998). Retinoic acid has light-adaptive effects on horizontal cells in the retina. Proc Natl Acad Sci 95: 7139-7144.

Zhang, DQ & McMahon, DQ (2000). Direct gating by retinoic acid of retinal electrical synapses. Proc Natl Acad Sci 97: 14754-14759.

Thesis period: 01.04.2001 – 14.02.2005 (scholarship period: 01.04.2001 – 31.03.2004)

Publications and lectures: Schütte, FH, Janssen-Bienhold, U, Weiler, R (2003). Identification and characterization of retinoic

acid-binding proteins in the carp retina. Proceedings of the 29th Göttingen Neurobiology Conference and the 5th Meeting of the German Neuroscience Society2003. Elsner, N & Zimmermann, H (eds). Thieme, Stuttgart, New York: p 514.

Schütte, FH, Janssen-Bienhold, U, Weiler, R, (2003). Identification and characterization of retinoic acid-binding proteins in the carp retina. IOVS 44: E-Abstract 3513.

Schuette, F, Janssen-Bienhold, U, Weiler, R (2002). Identification and characterization of retinoic acid-binding proteins in the fish retina. 3rd Forum of European Neuroscience: p. 296.

Cooperation with and/or relation to other projects: Cooperation with dissertation projects M. Greschner, Jennifer Shelley, Mark Pottek,

Timm Schubert. Collaboration and discussions in seminars and group meetings with the members of the retina neurobiology group (Oldenburg) and the vision physiology group (Groningen).

Participation in the study program: Attended courses: Seminars of the graduate school, 2001, 2001/2002, 2002, 2002/2003, 2003,

2003/2004, Oldenburg; own talks given June 2003 and July 2004 Monthly meetings in Groningen/NL and Oldenburg, 2001, 2001/2002, 2002,

2002/2003, 2003 Neurobiological seminars, 2001-2004, Oldenburg

Attended conferences: July 13-17, 2002: 3rd Forum of European Neuroscience (FENS); Paris, France Dec 04-06, 2002: NEURONORD Conference; Delmenhorst, Germany May 04-09, 2003: Meeting of the Association for Research in Vision and

Ophthalmology (ARVO); Fort Lauderdale, USA June 12-15, 2003: 29th Göttingen Neurobiology Conference / 4th Meeting of the

German Neuroscience Society; Göttingen, Germany



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Dipl.-Inform. Arne Schulz, Carl von Ossietzky Universität Oldenburg

Classification scheme for IP-componenents to enable power modelling

Thesis supervisor: Prof. Dr.-Ing W. Nebel, Fak. II, Dep. für Informatik, AG EHS

In the current embedded systems design one crucial part is the complexity of the designs which increases the critical time-to-market. Therefore great effort has been spent to bridge this design gap. Besides the automated design flow and the design entry on higher abstraction levels one very promising approach is the use of so called IP components. These Intellectual Property (IP) components can represent different grades of complexity ranging from simple combinatorial functions up to sophisticated implementations of complex algorithms. They can be available as in-house IP for the reuse of previously designed functions or as commercially available IP products.

For the efficient reuse a very good documentation and standardization is necessary. Even though IPs are already used for some time, the standardization is still in progress.

All currently known attempts lack of a well defined power description. This is caused by the fact, that the power consumption is depending on static and dynamic (simulation) data and therefore static analysis allown using a formula in the datasheet doesn't fit the needs in this point, while it may be sufficient e.g. for timing analysis.

The dissertation is currently in an early stage of completion. In the past year some good results could have been achieved which are currently to be published in well known conferences.

Thesis period: 7/ 2006

Publications and Lectures: Schulz, A. (2000).“ Rekonfigurierbare Hardware in der Praxis“, c’t Nr. 17/2000 Schulz, A. (2002).“ PRO-DASP: High Level Power Estimation for IP -Modules and Interconnect”, VIVA

Grundlagen und Verfahren verlustarmer Informationsverarbeitung. 3. Kolloquium des Schwerpunktprogramms der Deutschen Forschungsgemeinschaft. 18.-19.März 2002, TU Chemnitz

Publications in preparation: Schulz, A., (2005). „A High Level Constant Coefficient Multiplier Power Model for Power Estimation on

High Levels of Abstraction”, to appear in Proc. of PATMOS 2005 Schulz, A. (2005). „Verlustleistungsabschätzung und -optimierung auf hohen Abstraktionsebenen:

Modellierung von Funktionskomponenten und Leistungslängenabschätzung”, to appear in Proc. of INFORMATIC 2005

Cooperation with and/or relation to other projects: Prof. Dr. Dr. Birger Kollmeier: AG MEDI (Th. Rohdenburg, Dr. V. Hohmann) Prof. Dr. Alfred Mertins

Age when entering the graduate school: 30 Years (5 years ass. Member in 2005)


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Dr. Mailin Segger-Junius, Carl von Ossietzky Universität Oldenburg

Characterization of the dendritic localization of the shank1-mRNA

Thesis supervisor: Prof. Dr. Reto Weiler, Neurobiologie

Synaptic plasticity seems to be a key event for learning and memory formation. Long-lasting forms of synaptic plasticity require a new synthesis of specific proteins, which may occur locally in the dendrite. Components of the translational machinery as well as specific mRNAs have been identified in dendrites. One of these dendritic transcripts is the mRNA of one of the major scaffolding proteins of the postsynaptic density, Shank1. In this dissertation the dendritic localiziation of the Shank1-mRNA has been examined. In particular the cis-acting dendritic translocation element (DTE) in the mRNA has been identified. A comparison of the expression pattern of different splice variants of Shank1 has shown that the dendritic localiziation of the Shank1-mRNAs appears to be independent of the complex alternative splice events. In a cellular expression system the cis-acting DTE has been identified in the 3'UTR of the mRNA. It consists of the first 126 nucleotides of the 3'UTR. As a trans-factor of the dendritic localiziation of the Shank1-mRNA the RNA-binding protein Staufen has been identified.

Thesis period: July 2000 until June 2003

Publications and lectures: Böckers, T. M., Segger-Junius, M., Iglauer, P., Böckmann, J., Gundelfinger, E. D., Kreutz, M. R.,

Richter, D., Kindler, S., Kreienkamp, H. J. (2004). „Differential expression and dendritic transcript localization of Shank family members: identification of a dendritic targeting element in the 3' untranslated region of Shank1 mRNA”, Mol Cell Neurosci 26(1): 182-90.

Cooperation with and/or relation to other projects: Institute for Cell Biochemistry and Clinical Neurobiology, Hans-Jürgen Kreienkamp


Occupation after leaving the graduate school (if applicable): High school teacher education


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Jennifer Shelley, M.S., Carl von Ossietzky Universität Oldenburg

Horizontal Cells in the Mouse Retina: Physiology and Function

Thesis supervisor: Prof. Dr. Reto Weiler, AG Neurobiologie

Spatial Properties of Horizontal Cell Responses in the Mouse Retina Horizontal cells are coupled by gap junctions: the extensive coupling of the horizontal cells is reflected in their large receptive fields, which extend far beyond the dendritic arbor of the individual cell. In the mouse retina, horizontal cells express connexin57 (Cx57). Dye coupling of horizontal cells in Cx57-deficient mice is impaired, which suggests that the receptive field size of Cx57-deficient horizontal cells might be similarly reduced. To test this hypothesis we measured the receptive fields of horizontal cells from wildtype and Cx57-deficient mice. First, we examined the synaptic connections between horizontal cells and photoreceptors: no major morphological alterations were found. Moreover, horizontal cell spacing and dendritic field size were unaffected by Cx57 deletion. To characterize horizontal cell receptive field properties we used intracellular recordings. Length constants were computed for each cell using the cell’s responses to concentric spots of light of increasing diameter. We found that the receptive field size depends on the intensity of the stimulus used to measure it: increasing the stimulus intensity reduced the length constant. Deletion of Cx57 significantly reduced the receptive field size of horizontal cells. Dark resting potentials were strongly depolarized and response amplitudes reduced in Cx57-deficient horizontal cells compared to the wildtype. However, feedback was intact in Cx57-deficient horizontal cells, suggesting that Cx57-containing hemichannels are not involved in negative feedback of horizontal cells onto cones. These data thus provide the first quantification of mouse horizontal cell receptive field size and confirm the unique role of Cx57 in horizontal cell coupling.

Figure 1. Comparison of length constants from wildtype (filled circles; n = 17) and Cx57 lacZ/lacZ (open circles; n = 5) horizontal cells. Length constants were measured at several different intensities for each cell. Increasing stimulus intensity reduced the length constant. Cx57-deficient horizontal cells demonstrated smaller receptive fields than those from wildtype mice.

References Hombach S, Janssen-Bienhold U, Söhl G,

Schubert T, Büssow H, Ott T, Weiler R and Willecke K (2004) EJN 19:2633-2640.

Lamb (1976) J Physiol 263:239-255.

Adaptation in the Outer Retina of the Mouse The coupling of the horizontal cell network shows a bell-shaped relationship to the ambient light level: at high and low levels of ambient light, horizontal cell coupling is reduced, while at intermediate light levels, coupling is at its maximum (Xin and


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Bloomfield 1999). The mechanism underlying this phenomenon is not clear. Several factors have been shown to modulate horizontal cell coupling, including dopamine, retinoic acid and nitric oxide. How the various modulating factors work together to produce the bell-shaped relationship is not yet understood.

Presumably, the modulation begins with a signal from the light-sensitive cells: the rods, which make up 97% of the photoreceptors, and the cones, which make up the remaining 3%. Preliminary studies carried out in our lab showed that the bell-shaped relationship between horizontal cell coupling and ambient light is maintained in mice lacking functional rod photoreceptors. These surprising results suggest that 3% of the photoreceptors are sufficient to maintain this adaptive mechanism. To determine the extent to which the cones are required for modulation of horizontal cell coupling, we plan to examine the coupling patterns in mice whose cones are functionless due to deletion of the cyclic nucleotide-gated channel subunit A3 (Biel et al. 1999).

References Biel M, Seeliger M, Pfeifer A, Kohler K, Gerstner A, Ludwig A, Jaissle G, Fauser S, Zrenner E, Hofmann F (1999)

Proc Natl Acad Sci U S A. 96(13):7553-7. Xin D and Bloomfield SA (1999) J Comp Neurol 405:75-87.

Thesis period: 03/2003 – 03/2006 (projected); stipend received 03/2003 – 02/2006

Publications and lectures: Shelley, J, Dedek, K, and Weiler, R (2005) “Effects of Connexin57 Deletion on Horizontal Cell

Receptive Field Size in the Mouse Retina” Invest. Ophthal. Vis. Sci. 46:E-abstract 600. Shelley, J, Dedek, K, Schultz, K, Dirks, P, Schuldt, A, Janssen-Bienhold, U, and Weiler, R (2005)

“Expression of Connexins in Horizontal Cells of the Mouse Retina” Proceedings of the 6th Meeting of the German Neuroscience Society/ 30th Göttingen Neurobiology Conference 2005 eds. H. Zimmerman and K. Krieglstein Neuroforum 2005, 1 Suppl. abstract 167B.

Shelley, J (10/2004) the Jackson Laboratory Workshop “The Laboratory Mouse in Vision Research” presentation: “Morphology of the Cx57-lacZ mouse retina”

Publications in preparation: Shelley, J, Dedek, K, Schubert, T, Schultz, K, Hombach, S, Willecke, K, and Weiler, R (2005)

Horizontal Cell Receptive Fields Are Reduced in the Connexin57 Knockout Mouse, in preparation for The Journal of Neuroscience.

Cooperation with and/or relation to other projects: This project is built upon the work of Mark Pottek. Dr. Pottek established in our laboratory the intracellular recording and tracer injection techniques in the mouse retina. In addition, the initial experiments for the project “Adaptation in the Outer Retina of the Mouse” were performed by Dr. Pottek.

The project “Spatial Properties of Horizontal Cell Responses in the Mouse Retina” aims to prove that horizontal cells are coupled by Cx57; this was first demonstrated by Timm Schubert (Hombach et al. 2004). Dr. Schubert is closely involved in this project, performing intracellular dye injections to examine the morphology of horizontal cells from connexin57-deficient mice. In addition, Dr. Schubert is contributing tracer coupling data to the project “Adaptation in the Outer Retina of the Mouse.”

The project of Frank Schütte focused on the molecular mechanism of modulation of horizontal cell coupling by retinoic acid. Our projects therefore both attempt to understand light adaptation in the outer retina but approach the problem from different angles: Dr. Schütte examined the molecular mechanisms, while the current project explores the neuronal pathways.


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In addition to these straightforward collaborations, this project profits from continuous discussion and cooperation with other members of the retinal neurobiology laboratory (R. Weiler, Oldenburg) and the sensory physiology laboratory (J. Kretzberg, Oldenburg).

Participation in the study program (attended lectures, courses and conferences): 03/03-07/05: attending the regular graduate school program, including weekly

seminars of the graduate school and of the Neurobiology lab in Oldenburg (incl. one talk per semester)

06/2005: InterGK Statistics course, Prof. Dr. Hans Colonius 05/2005: Annual Meeting of the Association for Research in Vision and

Ophthalmology, Fort Lauderdale, FL, USA 03/2005: Visit by the graduate school "Cognitive Neurobiology" Tübingen, in

Oldenburg, oral presentation 02/2005: 6th Meeting of the German Neuroscience Society, Göttingen, Germany,

poster presentation 10/2004: Jackson Laboratory Workshop “The Laboratory Mouse in Vision Research,”

Bar Harbor, ME, USA, oral and poster presentations 08/2004: Summer school “Neurosensory Science and Systems” Bad Zwischenahn,

Germany 06/2004: FASEB meeting “Retinal Neurobiology” Saxtons River, VT, USA, poster

presentation 06/2004: visit to the graduate school "Cognitive Neurobiology" Tübingen, Germany. 09/2003: InterGK Workshop in Klosterbuuren, Odoorn, Netherlands



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Lavina M. Slabu, Rijksuniversiteit Groningen

Imaging Subcortical Auditory Activity in Humans using fMRI

Thesis supervisor: H. Duifhuis, Dept of Biomedical Engineering, Univ of Groningen, BCN NeuroImaging Center, The Netherlands

Although auditory information is processed in several subcortical nuclei, most auditory fMRI studies focus on auditory cortex and do not take the brainstem responses into account. One of the reasons for this is that at the brainstem level functional imaging is complicated due to heart beat related motion.

In a series of fMRI experiments we tried to measure auditory activation at the level of the inferior colliculus, an important brainstem area involved in auditory information processing. BOLD contrast images were acquired at a 3 Tesla MRI system with gradient echo planar imaging. Each volume comprised 41 slices with a thickness of 2 mm each. Long repetition times were used (12 s) in a sparse sampling design to minimize the influence of the echoplanar noise. No cardiac gating was applied. The imaging plane was chosen such that the inferior colliculi as well as the auditory cortex were scanned. Two different plane orientations were used. In 4 experiments the plane of orientation was transverse, while in 7 experiments a coronal orientation was applied.

Results indicate that a coronal imaging plane should be preferred when activity in the colliculi has to be imaged.

Thesis period: 15.10.2003-15.10.2007

Cooperation with and/or relation to other projects: fMRI-projects with auditory stimulation in the bcn (Duifhuis, Roerdink) and in Oldenburg (Uppenkamp/Kollmeier

Participation in the study program (attended Lectures, courses and conferences): Cochlea Modelling, Oldenburg, 2005 EGK symposium on sensory coding, Oldenburg, 2005


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Dipl.-Psych. Rike Steenken, Carl von Ossietzky Universität Oldenburg

Psychophysical investigation of unconscious cross-modal priming

Thesis Supervisor: Prof. Dr. Hans Colonius (Institut für Kognitionsforschung)

This dissertation project aims at contributing to controversial debates concerning the existence of unconscious perception. Here we investigate the effect of a subliminal stimulus of one modality (audition) on performance in a discrimination task in another modality (vision). In general, unconscious (or, implicit) perception is understood as perception occurring in the absence of awareness. The debate concentrates on the question if these implicit processes have an impact on cognitive functions like perceptions or actions. Despite decades of behavioural research leading to a more sophisticated understanding of the theoretical and empirical difficulties, the discussion about the existence of implicit perception and how to gauge it adequately still persists (Hannula, Simons & Cohen, 2005). Cheesman & Merikle (1984) propose to differentiate between measuring a subjective and an objective threshold. As a subjective measure of awareness, subjects are simply asked if they can perceive the stimulus. Unconscious perception is assumed when they report no awareness. The basic strategy is to systematically degrade the stimulus conditions until the subjects state not to have an experience of the stimulus anymore. The threshold is defined in terms of the minimal stimulus conditions necessary for someone to perceive the presented stimulus consciously. On the other hand, in an objective threshold condition the stimuli are degraded until subjects can no longer discriminate between two stimulus states better than chance using the SDT (Merikle & Daneman, 2000).

To prove perceptual processing in the absence of awareness many studies have an underlying assumption called the dissociation paradigm indicating two indices of perceptual processing. One index is presumed to indicate the stimulus information available to awareness, while a second is presumed to indicate the availability of stimulus information independent of the access to awareness. In this dissociation paradigm a demonstration of perception without awareness requires on the one hand unequivocal evidence that nothing is consciously processed proven by a direct measure of perception, and on the other hand that the information is nevertheless processed influencing cognitive functions. This influence would be indicated by a second, indirect index of perceptual processing. Although widely used, controversies still remain of what is an appropriate direct measure of awareness and if it exhaustively and exclusively measures all aspects of the conscious percept (Reingold & Merikle, 1988). Further evidence for the existence of unconscious perception would be to show qualitative differences in conscious and unconscious processes. If such a difference could not be measured and the two processes vary in the same way, it could be argued that there is only one basic underlying process and the “unconscious” only reflects a weak form of the conscious mechanism (Hannula et. al, 2005).

Generally, cross-modal perception enables a faster spatial localisation of objects in the environment, when the stimuli share spatial features (Frens, Van Opstal & Van der Willigen, 1995). The question addressed here is whether a subliminal stimulus (or stimulus feature) modulates the conscious percept (e.g., location of a supra-threshold


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stimulus) and/or facilitates an upcoming motor action (e.g., saccadic eye movement), respectively.

References: Cheesman, J. & Merikle, P. M. (1984). Priming with and without awareness. Perception &

Psychophysics, 36 (4), 387-395. Frens, M. A., Van Opstal, A. J., & Van der Willigen, R. F. (1995). Spatial and temporal factors determine auditory-visual interaction in human saccadic eye movements. Perception &

Psychophysics, 57 (6), 802-816. Hannula, D. E., Simons, D. J. & Cohen, N. J. (2005). Imaging implicit perception: promise and pitfalls.

Nature Reviews Neuroscience, 6, 247-255. Merikle, P. M. & Danemann, M. (2000). Conscious vs. Unconscious Perception. In: Gazzaniga, M.S.

(Ed.), The new cognitive Neurosciences (second edition) (1295-1303). Cambridge, Mass.: MIT Press.

Reingold, E. M. & Merikle, P. M. (1988). Using direct and indirect measures to study perception without awareness. Perception & Psychophysics, 44, 563-575.

State of the dissertation project Two experiments are intended to investigate the question mentioned above. In the first experiment, we seek to replicate the visual-auditory spatial congruence effect. An auditory noise (white) is presented over loudspeakers at the beginning of each trial (occurrence of central fixation point). Subjects are instructed to direct their gaze away from fixation toward a (weak) visual stimulus occurring either on top or bottom of a screen. Simultaneously (or with a certain time delay) a click is presented either on top or bottom. In the congruent condition (click and visual stimulus from the same direction) we expect saccadic RT facilitation, in the incongruent condition either inhibition or no effect.

In the second experiment the intensity of the click is set at d-prime= 0 level of recognizing the direction (top or bottom). This level is determined separately using the same eye movement task but with the subjects indicating, by button press, whether the click came from the top or from the bottom. The first experiment is then repeated with the auditory stimulus intensity at the d-prime= 0 level. A saccadic RT facilitation under these conditions would support the initial hypothesis of a subliminal stimulus effect.

Thesis period: 01.03.05-31.05.06

Cooperation with and/or relation to other projects: This dissertation project has a strong relationship to the project of Riklef Weerda based on the studied questions of conscious perception as well as on the employed model to engage perceptual sensitivity (SDT). Moreover there is a fertile interaction with Melanie Zokoll concerning homologous and analogous structures for perceptions and memory systems in man and animal.

List of attended courses: regularly: InterGK-seminar Oldenburg and Groningen; talk is given in June 2005

“Psychophysical investigation of unconscious cross-modal priming”. regularly: seminar: „Ausgewählte Methoden der Kognitionsforschung“ in Oldenburg. 22-24. March 05: Meeting with the Tübinger GK in Oldenburg. 24. June 05 statistic-course in Oldenburg.

List of attended conferences: 07-11. March 2005: Winterschule „Medizinische Physik und Audiologie“ in

Pichl/Steiermark, Austria.


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Dr. Claudia Steinbrink, Carl von Ossietzky Universität Oldenburg

Phonological and inflectional errors in the spontaneous speech of children with impaired and unimpaired hearing

Thesis supervisor: Prof. Dr. Gisela Szagun, Prof. Dr. Hans Colonius, Institut für Psychologie, Universität Oldenburg

Aims: The aims of this dissertation project were twofold. One aim was to evaluate the effect of impaired processing of auditory information on children`s spoken language competencies. This was achieved by comparing normal-hearing and hearing-impaired children with regard to frequencies of phonological and inflectional errors in spontaneous speech. The second aim was to investigate the influence of the stability of children`s phonological systems on their productions of inflectional morphemes. Therefore, relations between phonological and inflectional error frequencies in children´s language were studied.

Method: Phonological and inflectional errors in the spontaneous speech of normal-hearing children, moderately hearing-impaired children with hearing aids and deaf children with cochlear implants were analysed. Per group, 13 children participated. Children were monolingual speakers of German and were matched in mean length of utterance in morphemes (MLU): All children had an MLU between 3.0 and 4.5, which means that they produced multiword utterances. Two hundred utterances per child (mean: 1500 phonemes) were used for phonological analysis. Phonological errors consisted of the omission, substitution or addition of phonemes without function for inflection. Inflectional morphemes were analysed for the total speech samples (mean: 450 inflections). Inflectional errors were defined as omission, substitution or addition of inflections. Inflections were viewed as phonemes expressing inflection, allowing to analyse phonological as well as inflectional errors with respect to categories commonly used for phonological analysis (e.g. error type, word position of error, errors in consonant clusters, erroneous phoneme). For each error category, relative frequencies of phonological and inflectional errors were computed.

Results and Discussion: Analyses of variance showed that children with cochlear implants tended to produce more errors than the other two groups, but only few group differences were significant. Thus, although children with severe hearing impairment tend to produce more errors, there is no clear connection between hearing status and frequencies of phonological and inflectional errors in spontaneous speech. The lack of group differences seems to stem from children`s equivalent MLU levels. Hence, once children´s language development has progressed to multiword utterances, impaired processing of speech may not affect phonological and inflectional error frequencies in spoken language. In most error categories, phonological and inflectional error frequencies correlated significantly. This suggests that children´s phonological and inflectional systems are built up together. Moreover, this may indicate that inflectional errors are influenced by phonological shortcomings.

State of the dissertation project: finished; defense of dissertation in May 2004


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Thesis period: December 1998 – May 2004

Grant of the International Graduate School for Neurosensory Science and Systems received for December 2003

Publications and Lectures: Bitz, U., Gust, K., Vogt, K., Steinbrink, C. & Hille, K. (2005). Auswirkungen des AUDILEX-

Trainingsprogramms auf die Lese-Rechtschreibleistung von Grundschülern der 2. Klasse. Nervenheilkunde, 24 (3), 184-189.

Steinbrink, C. & Szagun, G. (1999). Der Einfluß überdeutlichen Sprechens auf den Sprach-erwerb von Kindern mit Cochlea-Implantat. Sprache - Stimme - Gehör, 23, 213-217.

Steinbrink, C. (2004). Phonologische und flexionsmorphologische Fehler in der Sprache normalhörender und hörgeschädigter Kinder. Dissertation, Universität Oldenburg. Elektronische Ressource: http://docserver.bis.uni-oldenburg.de/publikationen/dissertation/2004/stepho04/stepho04.html.

Szagun, G., Fogel-Rosen, A., Ziehm, A., Ricken, A., Steinbrink, C. & Greenbaum, C. (2003). Häusliche Umwelt und Kindergarten in der Entwicklung hörgeschädigter Kinder mit Cochlea-Implantat und Hörgeräten und normal hörender Kinder. Hörgeschädigte Kinder - Erwachsene Hörgeschädigte, 3/2003, 115-127.

Szagun, G. & Steinbrink, C. (2004). Typikalität und Variabilität in der frühkindlichen Sprachentwicklung: eine Studie mit einem Elternfragebogen. Sprache - Stimme - Gehör, 28, 137-145.

Szagun, G, Steinbrink, C., Franik, M. & Stumper, B. (in press). Development of vocabulary and grammar in young German-speaking children assessed with a German language development inventory. First Language.

Publications in preparation: Riecker, A., Ackermann, H., Wilke, M., Schmitz, B. Vogt, K. & Steinbrink, C. (2005). Bilateral language

function in collosal agenesis: An fMRI and DTI case study. Manuscript submitted for publication.

Cooperation with and/or relation to other projects: Hearing Instrument research group (B. Kollmeier/V.Hohmann)

Participation in the study program (attended lectures, courses and conferences): Regular attendance at Oldenburg seminar (2001 – April 2004) Regular attendance at research colloquium of the Institut für Kognitionsforschung / Abteilung Kognitionsforschung (till April 2004) Modeling in Cognitive Neurosciences. 5th Summer School in Behavioral and Cognitive Neurosciences, Groningen (The Netherlands), July 3 - 7, 2000. Brain Plasticity and Critical Periods. Symposium at the School of Behavioral and Cognitive Neurosciences, Groningen (The Netherlands), June 23, 2003.

List of stays abroad: Participation in the regular exchange seminar Oldenburg-Groningen Participation in International Conferences: Steinbrink, C. (2001). Phonological errors in the language of German-speaking

children and their relations to morphology. Poster presented at the Child Language Seminar, Hertfordshire (England), July 9-11, 2001.

Steinbrink, C. & Szagun, G. (2001). Phonological and morphological errors in the spontaneous speech of children with cochlear implants and with normal hearing. Poster presented at Xth European Conference on Developmental Psychology, Uppsala (Sweden), August 22-26, 2001.

Steinbrink, C. & Szagun, G. (2002). Relations between phonological and inflectional errors in German-speaking children with cochlear implants and with unimpaired hearing. Poster presented at IXth International Congress for the Study of Child Language, Madison (Wisconsin, USA), July 16 - 21, 2002.


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Occupation after leaving the graduate school (if applicable): Research associate at Transfer Center for Neuroscience and Learning, University of Ulm, Germany


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Dipl-Math MSc Stefan Strahl, Carl von Ossietzky Universität Oldenburg

Efficient coding of natural sounds

Thesis supervisor: Prof. Dr.-Ing. Alfred Mertins, Signal Processing Group

Environmental sound, speech and music are highly structured signals, and there is reason to believe that the auditory system is highly adapted to capture such structure. In my work I try to characterise this manifold of natural sounds. With the learned structure, improvements can be achieved in e.g. audio compression or feature extraction for speech recognition.

The main concept is to mimic the evolutionary optimization that took place in the neurosensory system of the (human) brain. The auditory pathway has learned to solve the problems of information, computational and energy bottlenecks [1]. It has been shown that the mammalian brain achieves this by finding representations with reduced redundancy in comparison to the primary sensory signal [2].

Mathematical Background Coding the signal according to its most important components can be done by using Principle Component Analysis (PCA), Independent Component Analysis (ICA) and more recently by Sparse Coding [3,4]. All of these methods, however, work on a fixed time grid, correlating the basis functions with the signal at fixed time locations. Recent time-frequency decompositions (Matching/Basis Pursuit) have been proposed, which work with overcomplete basis functions and which can include functions at arbitrary positions. These methods fit basis functions to the best possible time location and it has been shown that the learned coding filters resemble the gamma-tone filters found in the cochlear [5].

An audio signal x can be represented as x = As where A is the basis and s the basis coefficients or the internal representation in the context of neurosensory systems. Algorithms reducing the redundancy in the basis coefficients s can thereby mimic the optimisation that the auditory system learned. In this dissertation, methods to find the optimal basis A for a given data set are addressed and possible improvements of this efficient representation for audio compression and speech recognition will be investigated.

State of the dissertation project A Matlab toolbox has been developed that can learn a data-dependent basis A for a given sound corpus x and various algorithms using on-line and off-line learning. Different ICA algorithms (noisy overcomplete ICA, fastICA, JADE, relative Newton method,CICAAR,…) and sparse coding algorithms (Matching Pursuit, Basis Pursuit,…) have been implemented. For evaluation, different sound corpora (TIMIT, bird songs, tonal speech, SQAM, pop music,…) have been set up. At the moment, evaluations of the different algorithms on the whole sound corpora are computed.

As in the overcomplete case, finding the sparsest representation (minimise L0-Norm) is NP-hard, this evaluation is computationally very expensive. But latest results in the field of sparse coding [6] have shown that the problem of finding the sparsest representation can, under some side conditions, be reformulated as an Lp-Problem


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with p=1 resulting in a convex problem. So as a next step, these results will be incorporated in the toolbox reducing the computation time significantly.

As the first example application, audio compression has been chosen. To benefit from the predominant zeros in the sparse representation, a significance trees / zero tree coding scheme from image coding has been adopted to audio coding (CSTQ). As the sparse representation has a different structure than e.g. MDCT coefficients, CSTQ has been extended to arbitrary significance trees, and a learning algorithm finding the optimal set of significance trees for sparse coefficients will be implemented.

A second application will be automatic speech recognition (ASR) where the efficient signal representation will be evaluated with existing ASR systems. Barlow, H.B. Possible principles underlying the tranformation of sensory messages

Sensory Communication, ed. WA Rosenblith, pp. 217-34 Cambridge, MA: MIT Press (1961) Atick, J.J What does the retina know about natural scenes? Neural Comput. 4:196-210 (1992) Abdallah, S.A. Plumbley, M.D. If edges are the independent components of natural images,

what are the independent components of natural sounds? Proceedings of ICA2001, San Diego, pp. 534-539 (2001)

Lewicki, M.S. Efficient coding of natural sounds Nature Neurosci. 5(4):356-363 (2002) Smith,E. Lewicki, M.S. Efficient coding of natural sounds using spikes predicts cochlear filters

Neural Information Processing Systems conference December 15, Vancouver, Canada (2004) Donoho,D. Tsaig,Y. Recent Advances in Sparsity-driven Signal Recovery

Proceedings of ICASSP2005, Philadelphia, USA (2005)

Thesis period: Graduation started 08-2003 and will be finished in 08-2006

Publications and Lectures: Zhou,H. Mertins,A. Strahl,S. An Efficient, Fine-Grain Scalable Audio Compression Scheme 118th

Audio Engineering Society Convention, Barcelona Spain (2005), Preprint No. 6435.

Publications in preparation Strahl,S. Zhou,H. Mertins,A. An Adaptive Tree-Based Progressive Audio Compression Scheme IEEE

Workshop on Applications of Signal Processing to Audio and Acoustics, New Paltz, NY (2005) – submitted & accepted

Cooperation with and/or relation to other projects: Stefan Heise: exchange on spectro-temporal filters found by a psychoacoustic

approach Julia Maier: with Rainer Beutelmann development of a scene analysis and pattern

recognition tool for semi-automatic gerbil head orientation tracking Georg Klump: analysis und discussion of the learned overcomplete dictionaries in the

context of their biological resemblance / evidence Jutta Kretzberg: fertile interaction on questions of biological evidence of progressive

coding in neurosensory systems Jesko Verhey: analysis und discussion of the learned overcomplete dictionaries in

context of their time-frequency resolution and neurophysiological resemblance Huan Zhou: conjoint development of an progressive audio coding algorithm using

significance trees Melanie Zokoll: MATLAB tool generating randomly distributed experiment setups with

additional side conditions

Participation in the study program (attended lectures, courses and conferences): InterGK seminar, weekly during semester, Oldenburg InterGK meetings, monthly, Groningen/Oldenburg


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4.-6.9.2003 Summerschool Odorn 10-13.3.2004 DGA’04, , Leipzig, Deutschland 19.8.04 Summerschool Bad Zwischenahn (poster presented) 18.-23.03.2005 ICASSP’05, Philadelphia, USA (special session ‘sparse coding’

attended) 28.-31.05.2005 118th AES Convention, Barcelona,Spain (talk given) 16.-19.10.2005 2005 IEEE Workshop on Applications of Signal Processing to

Audio and Acoustics (lecture given)

Teaching/supervision/ counseling within the graduate school: WS 03/04 Block course „Psychophysik und Neurosensorik”, Oldenburg, Germany WS 03/04 Betreuung Physikpraktikum WS 03/04 Talk presenting Michael Lewickis work SS 04 Talk on “TikiWiki as a Groupware Tool” SS 04 Betreuung Neurosensorik Blockpraktikum: fMRI WS 04/05 Talk on “Efficient coding of natural sounds” WS 04/05 Betreuung DSP Blockpraktikum: Feature Extraction with GMMs WS 04/05 Lecture on “ICA in Audio” WS 04/05 Talk on “Sparse Coding of Audio Data” Installing and training for groupware tool TikiWiki (http://www.tikiwiki.org) Maintaining of Webpages of graduate school Setting up of a videoconference system for graduate school General matlab / computer science consulting for other graduates

List of stays abroad: 18.-23.03.2005 ICASSP’05, Philadelphia, USA 28.-31.05.2005 118th AES Convention, Barcelona,Spain 16.-19.10.2005 WASPAA05, New Paltz, NY, USA



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Sonja Tomaskovic, Rijksuniversiteit Groningen

Audio-visual Integration in Speech Perception: An fMRI Study using the McGurk Effect

Thesis supervisor: H. Duifhuis, Department of Biomedical Engineering, University of Groningen, BCN NeuroImaging Center, Groningen, The Netherlands

In speech perception both auditory and visual information is important. Especially in a noisy environment visual information can improve speech intelligibility. How auditory and visual information is combined is largely unknown. To investigate this process we use the McGurk effect. This effect is a useful tool for studying audio-visual (AV) integration, since, in the McGurk effect, the auditory perception is changed due to AV integration. E.g., when the speech sound /aba/ is presented while a moving mouth pronouncing the sound /aga/ is shown, hearing /ada/ indicates AV integration. In psychophysical experiments the strength of the McGurk effect was studied as a function of AV synchronicity. AV time shifts ranging from -620 ms to +420 ms were used. Based on psychophysical data fMRI stimuli for minimum, intermediate or maximal strength of the McGurk effect were selected. The sparse sampling technique was used to record the fMRI data. Given the assumption that the strength of the McGurk effect reflects the strength of AV integration, we expected to find a correlation in brain activation and AV synchronicity of areas involved in AV integration.

Thesis period: 01.10.2001-01.11.2005

Publications and lectures: Renken, R., Wiersinga-Post, J. E. C., Tomaskovic, S., and Duifhuis, H. (2004). 'Dominance of missing fundamental versus spectrally cued pitch: Individual differences for complex tones with unresolved harmonics,' J.Acoust. Soc. Am. *115* (5), 2257-2263.

Cooperation with and/or relation to other projects: fMRI-projects with auditory stimulation in the bcn (Duifhuis, Roerdink) and in Oldenburg (Uppenkamp/Kollmeier

Participation in the study program (attended Lectures, courses and conferences): - regular participation in the monthly InterGK meetings - Neuro Noord Conference 2002 - Mind and Brain III 2003 & IV 2004 - Human Brain Mapping, Toronto, 2005 - EuroGK, Copenhagen, 2003 - auditory Cortex Meeting 2003 - ARO conference 2004 & 2005


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Lic. Psychol. Ignacio Vallines, Carl von Ossietzky Universität Oldenburg

Modulation of neural activity in Human visual cortex during saccade programming

Thesis supervisor: Mark W. Greenlee

Psychophysical data have shown that the decrease in visual sensitivity experienced during the execution of saccades starts approx. 75 ms before the onset of the eye movement. The perception of briefly presented stimuli during the presaccadic interval is impaired despite the fact that these stimuli are projected onto the stationary retina. Main goal of this dissertation project is to measure BOLD responses to retinotopically-localized stimuli inmediately before the onset of a horizontal eye movement to a visual target, and observe if signals arriving to primary visual cortex are already suppressed. This would mean they never reach higher processing areas.

In order to increase the probability of presenting these stimuli immediately before the eye movement onset, a predictive algorithm with an online saccadic detection routine was developed and used throught the fMRI experiments. In our event related design, the stimulus onset asynchrony (SOA: time distance between the onset of the stimulus and the onset of the eye movement) is parametrically correlated to the BOLD signal produced by the stimuli in V1. The BOLD-signal’s amplitude elicited in V1 by flashed stimuli significantly decreased with decreasing SOA. Event though their retinal images were identical, stimuli presented very close to the saccadic onset were often not perceived. Our findings clearly suggest that saccadic suppression is evoked at a subcortical level, before stimulus-driven activity reaches visual cortex.


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Thesis period: 01.10.2001 – 12/ 2005

Granting period: 01.10.2001-31.01.2004 (continuation at Univ. Regensburg)

Publications and Lectures: Vallines, I., Rutschmann, R.M., Özyurt, J., Bodis-Wollner, I.G., Greenlee, M.W. Primary visual cortex

activation during intentional saccadic eye movements and shifts in spatial attention. (currently under review).

Weerda, R., Vallines, I., Thomas, J.P., Greenlee, M.W. Nonspatial selective and divided attention to subtle difference in color and shape: psychophysics and fMRI. (submitted for publication).

Weerda, R., Vallines, I., Thomas, J. P. & Greenlee, M. W. (2003). Individual Differences in Cognitive Strategies and Attentional Effects During Stimulus Uncertainty: Evidence from Psychophysics and fMRI. In: Reinvang, I., Greenlee, M. W. & Herrmann, M. (Eds.) The Cognitive Neuroscience of Individual Differences - New Perspectives. Hanse Advanced Studies, Vol IV.

Vallines I, Bodis-Wollner IG, Nagengast B, Özyurt J, Rutschmann RM, Greenlee MW (2002). Saccades in the dark: fMRI evidence for separate cortical control of intentional eye movements. Perception, Vol.31, Suppl., 178.

Özyurt J, Rutschmann RM, Vallines I, Greenlee MW (2002). Event-related fMRI of saccadic response inhibition. Perception, Vol.31, Suppl., 177.

Thomas, J. P., Weerda, R., Vallines, J. I., & Greenlee, M. W. (2002). Comparison of fMRI responses during discrimination under certainty and uncertainty conditions. Journal of Vision, 2(10), 5a.

Vallines I, Thomas J P, Greenlee M W (2001). Concurrent judgments of colour and shape. Perception, Vol.30, Suppl., 14.

Weerda R, Thomas J P, Vallines I, Greenlee M W (2001). Neocortical areas underlying shape and colour discriminations as assessed by fMRI. Perception, Vol.30, Suppl., 14

Cooperation with and/or relation to other projects: Project R. Weerda,fMRI-techniques (S. Uppenkamp/group B. Kollmeier, groups D. Duifhuis, J. Roerdink)


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Participation in the study program (attended lectures, courses and conferences): Courses Statistical Parametric Mapping SPM2 at the Universitätsklimikum Hamburg-

Eppendorf. Brain Voyager QX/2002 at the University of Maastricht. Brain Imaging (fMRI/MEG/EEG) at the Otto-von Guericke Universität Magdeburg.

Conferences Early Stage Research Mobility in Europe (ERSM2004). February 24-27, 2004.

Lisbon, Portugal. Brain Plasticity and Critical Periods. June 23rd 2003 Groningen. Holland. Metting of the European Graduate School for Neurosensory Science and Systems

and the Graduate School of Neuroscience. May 24-26 2003, Copenhagen. Denmark.

Vision Sciences Society annual meeting (VSS). May 10-15, 2003 Sarasota, Florida, USA.

BCN- School of Behavioral and Cognitive Neuroscience Retreat. April 16-17 2003, Doorwerth. Ho lland.

NeuroNord Conference on Cognitive and emotional neuroscience. December 4-6, 2002. Hanse Institute for Advanced Study Delmenhorst, Germany.

International Conference on the Cognitive Neuroscience of Individual Differences - New Perspectives. November 7 - 10, 2002, Hanse-Wissenschaftskolleg Delmenhorst, Germany.

European Conference on Visual Perception (ECVP). August 25-29, 2002. Glasgow, Scotland.

Neurosensory Science, Systems and Applications meeting. February 20-22, 2002. Groningen, Holland.

European Conference on Visual Perception (ECVP). August 26-30, 2001. Kusadasi, Turkey.

List of stays abroad: State University of New York (USA). Research fellow, working on a joint project on

fMRI and electro-physiology at the department of Neurology (Downstate Medical Center). (Invited by Professor Bodis-Wollner, December 2002).

Kantonspital Basel (Switzerland). Collaboration in a fMRI-Oculomotor project with schizophrenic patients (at the department of Neuroradiology invited by Professor Radü, March 2003).


Occupation after leaving the graduate school (if applicable): Wiss. Mitarbeiter Universität Regensburg


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Dipl.-Psych. Riklef Weerda, Carl von Ossietzky Universität Oldenburg

The Human Primary Visual Cortex and its Role in Visual Awareness and Visual Search

Thesis Supervisor: Prof. Dr. Hans Colonius, Section of Cognitive Research, Department of Psychology, School of Humanities and Social Sciences, Carl von Ossietzky University Oldenburg Prof. Dr. Mark W. Greenlee, former affiliation: Section of Cognitive Research, Department of Psychology, School of Humanities and Social Sciences, Carl von Ossietzky University Oldenburg, present affiliation: Department of Experimental Psychology, University of Regensburg

Introduction The primary visual cortex (V1) is one of the most intensely studied parts of the (human) brain, so that we know more about the function of its neurons than about hardly any other cortical neurons. Nevertheless there is still substantial debate concerning the role of V1 in conscious visual perception. One of the predominant opinions is that it makes a direct and necessary contribution to the emergence of conscious visual perception. The other major opinion is that it is more like a relay station passing information to higher visual cortical areas that are capable of complex enough processing of visual information to be part of the neuronal correlate of visual awareness. This issue was and is studied with a multitude of different approaches, ranging from single unit measurements in animals and lesion studies to EEG and functional imaging techniques. The answers found by these different studies are controversial (see Tong, 2003, and Rees et al., 2002, for reviews).

In a recent study in this context, Ress & Heeger (2003) used a near-threshold contrast detection task in combination with the method of event-related functional magnetic resonance imaging (efMRI), which provides an indirect measure of neuronal activity by the measurement of the blood oxygenation level and the calculation of BOLD (Blood Oxygenation Level Dependent) contrasts. They arrived at the conclusion that the retinotopic activity in V1 correlates more with the percept than with the actual stimulus intensity, which is a hint towards a direct contribution to visual awareness by V1.

Given the fact that the strength of a neuronal response to a certain stimulus is always perturbed by noise of different sources and therefore variable within a certain range, it would be interesting to dissociate as far as possible the physical intensity of a stimulus from the percept it causes, since this would make it possible to determine more precisely which of these two correlates more with the activity of V1 neurons.

Methods It turned out to be quite difficult to find a stimulus context in which relatively large differences in luminance contrast remain undetected and which is compatible to the constraints of an efMRI experiment. In the first experiment, an uncertainty paradigm was used in which subjects are uncertain about the spatial location of the target stimulus. In each trial four stimuli were presented against a uniform grey background simultaneously for 200 ms on a 6° radius around the fixation point, which were identical in size and mean luminance. Each stimulus was a random block pattern of a certain luminance contrast. The three distractors had a contrast of 10 %, whereas the


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contrast of the target was adjusted to the subjects’ individual detection threshold within this stimulus context. Typical values were 12.5% contrast for a detection probability of p = 0.6 and 14.5% percent contrast for a detection probability of p = 0.8 (chance level was at p = 0.25). The subjects had to permanently fixate the central fixation cross and determine via button press after each stimulus presentation, at which of the four possible locations the target stimulus was presented. Before the main experiment, subjects were extensively trained on the task in order to avoid any learning effects during the main experiment and after this training the threshold of every subject was measured in order to adjust the luminance contrast levels of the target. Data of four subjects (three female, one male; mean age 23.9) were collected, where each performed 2,016 trials in the main experiment.

Provided the subject responded correctly, the neuronal activity in the part of V1 that retinotopically corresponded to the target stimulus was that during a hit, whereas that one in the parts of V1 corresponding to the distractors matched correct rejections. In the reverse case, the neuronal equivalents of a miss (at the actual target location), a false alarm (at the erroneously assumed target location) and again two correct rejections (at the other two distractor locations) were measured. Since the activity of neurons in V1 generally increases with increasing luminance contrast (Wandell et al., 1999; Goodyear & Menon, 1998), it was then possible to determine whether the neuronal activity in V1 correlates more with the actual stimulus intensity or with the conscious percept by analysing the collected efMRI data in terms of the response categories of the signal detection theory and comparing the neuronal activity during hits, misses, false alarms and correct rejections, where the latter served as baseline.

The employment of two different target stimulus intensities (yielding 60% and 80% correct responses, respectively) provided the opportunity to test if this parameter of stimulus intensity influences the correlation between neuronal activity in V1 and conscious perception.

In addition to the efMRI measurements carried out during the main experiment and to a high-resolution anatomical scan, further measurements were performed for the functional determination of the regions of interest (ROIs) within V1 which retinotopically correspond to the four stimulus locations. This enabled the subsequent ROI analysis of the efMRI data collected in the main experiment and was necessary to ensure that the possible effects are retinotopically specific. High-contrast checkerboard stimuli that were contrast-reversing at a rate of 5 Hz were presented sequentially at each of the four stimulus locations alternating with presentations of the uniform grey background.

During all measurements, the eye movements of the subjects were controlled with an MR-Eyetracker (CRS Ltd., Rochester, UK) in order to control fixation. Trials during which subjects did not hold fixation properly were excluded from the statistical data analysis, which was performed with the standard analysis software SPM2 developed by the Functional Imaging Laboratory at the University College London (http://www.fil.ion.ucl.ac.uk/spm/). This method employs the general linear model and multiple t-tests to calculate linear regressions for the analysis of time series of fMRI data.

In the second experiment, a change blindness paradigm is used, where relatively large changes in stimulus intensity can be introduced during a short (500 ms) blank period between stimulus presentations. The methods will be similar to that described above for the first experiment, except that stimuli are presented two times for 1,500 ms, separated by a blank period of 500 ms. The luminance contrast of one of the four


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different stimuli will be increased from the first to the second presentation. Since larger differences in stimulus intensity can be used while still keeping the same detection probabilities, even more obvious results are expected than in the first experiment.

Results Exemplary results of the first experiment are shown in fig. 1 for one subject and one of the four ROIs. As can be seen in this graph, the neuronal activity in V1 correlates much more with perception than with the physical stimulus intensity. This is especially clarified by the fact that the activity during false alarms is comparable to that one during hits and clearly stronger than during misses.

The abovementioned effect is modulated by the contrast intensity of the target stimulus, as is demonstrated in fig. 2. The stronger the intensity of the target stimulus, the stronger is the BOLD response during hits and false alarms and the weaker it is during misses, respectively. This parallels the different stimulus intensity differences between target and distractor stimuli. The stronger the intensity of the target stimulus, the stronger the neural activity at the retinotopic location corresponding to a false alarm has to be to enable this erroneous response and the weaker it has to be at the retinotopic location corresponding to a miss to prevent the target from being detected.

Taken together these results support the notion that V1 is part of the neuronal correlate of conscious visual perception. This finding will be further examined with the second experiment using the aforementioned change blindness paradigm.

Fig. 1: Mean event-related BOLD responses of one of the four subjects in one of the four ROIs during hits, false alarms and misses (correct rejections = baseline)

Fig. 2: Parametric modulation of the retinotopic BOLD responses during hits, false alarms and misses by the luminance contrast intensity of the target stimulus


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References Goodyear, B. G., Menon, R. S. (1998). Effect of luminance contrast on BOLD fMRI Response in

human primary visual areas. Journal of Neurophysiology, 79, 2204-2207. Rees, G., Kreiman, G., Koch, C. (2002). Neural correlates of consciousness in humans. Nature

Reviews Neuroscience, 3, 261-270. Ress, D., Heeger, D. J. (2003). Neuronal correlates of perception in early visual cortex. Nature

Neuroscience, 6, 414-420. Tong, F. (2003). Primary visual cortex and visual awareness. Nature Reviews Neuroscience, 4, 219-

229. Wandell, B. A., Poirson, A. B., Newsome, W. T., Baseler, H. A., Boynton, G. M., Huk, A., Gandhi, S.,

Sharpe, L. T. (1999). Color signals in human motion-selective cortex. Neuron, 24, 901-909.

State of the Dissertation Project Right now, the project is in the state of data collection for the second experiment. Apart from the extensive search for experimental settings suitable for the aims of this project, several other steps have been completed before.

All of the necessary steps in the development, purchasing and installation of the apparatus have been completed. This includes the purchasing and installation of the necessary computer hardware for experimental control, data collection and eye movement controlling and its adequate synchronisation with the MR scanner. A suitable MR-compatible button press system (LUMITouch, Photon Control Inc., Burnaby, Canada) for the collection of the behavioural data had to be found, purchased and installed. Furthermore, I measured the luminance functions of the CRT display used for the training of the subjects and of the LCD projector used with the MR scanner to perform gamma corrections of the stimuli.

Additionally, I worked with and tested different programming environments for the development of experimental control (E-Prime, Presentation, Psychophysics Toolbox) and tested their temporal precision. The experimental control was then programmed with E-Prime and the stimuli were generated with MatLab.

In the context of other projects in our working group, I participated in a variety of other fMRI experiments to deepen my knowledge of the method and to gather practical experience. This enabled me to identify and fine-tune the best suitable experimental parameters for the collection of fMRI data within my dissertation project.

Finally, I expanded my knowledge concerning the fundamentals and possible applications of the data analysis software packages SPM2 and BrainVoyager. This included the attendance of courses at the University of Maastricht (BrainVoyager) and the Universitätsklinikum Eppendorf in Hamburg (SPM2).

Thesis Period July 2003 - June 2006

Funding period within the International Graduate School: • as associated member: February 1st 2004 – December 31st 2004 • as scholarship holder: January 1st 2005 – May 31st 2006

Publications and Lectures

Publications: Weerda, R., Vallines, I., Thomas, J. P., Rutschmann, R. M., Greenlee, M.W. (submitted). Effects of

nonspatial selective and divided visual attention on fMRI BOLD responses. Submitted for publication in Experimental Brain Research.

Weerda, R. Vallines, I., Thomas, J. P., Greenlee, M. W. (2003). Individual differences in cognitive strategies and attentional effects during stimulus uncertainty: evidence from psychophysics and fMRI. In: Reinvang, I., Greenlee, M. W., Herrmann, M. (Eds., 2003). The Cognitive


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Neuroscience of Individual Differences – New Perspectives. Hanse Studies, volume 4. Oldenburg: Bibliotheks- und Informationssystem der Universität Oldenburg.

Weerda, R., Vallines García, J. I., Thomas, J. P., Greenlee, M. W. (2003). Individuell unterschiedliche kognitive Strategien während Reizunsicherheit - Psychophysik und fMRT. 45. Tagung experimentell arbeitender Psychologen. In: Experimentelle Psychologie. Golz, J., Fraul, F., Mausfeld, R. (Eds., 2003). Lengerich: Pabst Science Publishers, p. 227.

Weerda, R., Vallines, I., Thomas, J. P., Greenlee, M. W. (2002). Untersuchung der neuronalen Korrelate von Farb- und Formunterscheidungen mittels fMRT. 44. Tagung experimentell arbeitender Psychologen. In: Experimentelle Psychologie. Baumann, M., Keinath, A., Krems, J. F. (Eds., 2002). Regensburg: Roderer, p. 232.

Özyurt, J., DeSouza, P., West, P., Weerda, R., Rutschmann, R. M., Greenlee, M. W. (2002). Kortikale Aktivität und okulomotorisches Verhalten bei visuell geleiteten und gedächtnisgeleiteten Sakkaden. 44. Tagung experimentell arbeitender Psychologen. In: Experimentelle Psychologie. Baumann, M., Keinath, A., Krems, J. F. (Eds., 2002). Regensburg: Roderer, p. 175.

Thomas, J. P., Weerda, R., Vallines, J. I., Greenlee, M. W. (2002). Comparison of fMRI responses during discrimination under certainty and uncertainty conditions [Abstract]. Journal of Vision, 2, 5a.

Weerda, R., Thomas, J. P., Vallines, J. I., Greenlee, M. W. (2001). Neocortical areas underlying shape and colour discriminations as assessed by fMRI. 24th European Conference on Visual Perception, Perception, 30, Suppl., 114.

Lectures: Weerda, R., Vallines, I., Thomas, J. P., Greenlee, M. W. (2002). Individual differences in cognitive

strategies and attentional effects during stimulus uncertainty: evidence from psychophysics and fMRI. Poster talk at the international workshop ”The Cognitive Neuroscience of Individual Differences – New Perspectives”, Hanse Wissenschaftskolleg, Delmenhorst, Germany.

Cooperation with and/or relation to other projects: This dissertation project has strong relationships concerning the studied questions as well as the employed methods to the projects of Ignacio Vallines (group of Prof. Dr. Mark W. Greenlee), Rike Steenken (group of Prof. Dr. Hans Colonius), Dr. Petra Arndt (Oldenburg) and Dr. Frans Cornelissen (Groningen). Cooperation in methodological questions concerning fMRI takes place with Dr. Stefan Uppenkamp (group of Prof. Dr. Dr. Birger Kollmeier). Cooperation with projects from outside the InterGK is going on with Dipl.-Psych. Jale Özyurt (Oldenburg), Dr. John-Dylan Haynes (University College London, UK) and Prof. Dr. James P. Thomas (University of California, Los Angeles, USA).

Participation in the study programme (attended lectures, courses and conferences): weekly colloquium of the InterGK, Oldenburg monthly meetings of the InterGK in Groningen and Oldenburg summer school of the InterGK “Object perception: physiology, psychophysics and

models”, 2004, Bad Zwischenahn weekly colloquium „Anleitung zum wissenschaftlichen Arbeiten“, Oldenburg weekly neurobiology colloquium, Oldenburg seminar „Experimentelle Ansätze der Bewußtseinsforschung“, 2004, Oldenburg seminar „Ausgewählte Themen der Kognitionsforschung“, 2004/2005, Oldenburg seminar „Einführung in MatLab“, 2004, Oldenburg course „SPM 2004 – 7. Kurs zur funktionellen Bildgebung (Intensiv)“, 2004, Hamburg June 2004, visit at the graduate school „Kognitive Neurobiologie”, Tübingen,

Germany March 2005, visit of the graduate school „Kognitive Neurobiologie”, Tübingen, in

Oldenburg

Teaching/supervision/ counselling within the graduate school: “Kognitive Neuropsychologie”, Seminar, winter term 2003/2004


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List of stays abroad: bimonthly meetings of the InterGK in Groningen



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Dr. ir. Alle Meije Wink, Rijksuniversiteit Groningen


Thesis supervisor: Prof. dr. Jos B.T.M Roerdink, Institute for Mathematics and Computing Science, University of Groningen

Summary This project concerned the application of wavelet methods for denoising and improved statistical analysis of fMRI time series data. MR images are generally magnitude images, and if the (complex) noise is Gaussian distributed, its magnitude is Rician distributed. Most fMRI analysis methods, however, assume Gaussian distributed noise, without mentioning the Rician distribution of MR data. The difference between two images containing Rician noise, with the same underlying image and the same signal-to-noise ratio (SNR) is, to close approximation, Gaussian distributed. We find that the probability density function of this difference (i) approximates a Gaussian very well, and (ii) actually decays faster to zero than a Gaussian. A number of wavelet-based denoising schemes was tested in the context of functional MR time series analysis, and compared to Gaussian smoothing. Wavelet-based denoising methods are shown to improve

the SNR beyond higher input values than Gaussian smoothing. In addition, the activation patterns found after denoising remain closer, in terms of false positives and false negatives, to the original images.

A new method to extract a HRF from an fMRI data set was developed by adapting the Fourier Wavelet Regularized Deconvolution (ForWaRD) method (Neelamani et

al. 2004) to extract the HRF from fMRI time series. The extracted HRF coefficients are used to fit a novel HRF model, which can be used in the analyses of other data sets. Combining the new model with the extracted HRFs proves to yield a powerful analysis tool in subsequent ANCOVAs of similar data sets. The ForWaRD-based HRF extraction routine was extended to support families of wavelet basis functions which do not have compact support in the time domain.

An efficient algorithm to compute the shift-invariant discrete wavelet transform (SI-DWT) in the frequency domain was developed. Comparisons of the computation times of the time-domain SI-DWT and the frequency-domain SI-DWT show that the frequency-domain version is much faster for long signals.

Thesis period: January 2000- March 2004

Publications and lectures: Wink, A. M. and Roerdink, J. B. T. M. (2002), Enhancing functional neuroimages: wavelet denoising as

an alternative to Gaussian smoothing, in ‘Proc. International Conference on Computer Vision and Graphics’, Vol. 2, pp. 787 792.

Wink, A. M. and Roerdink, J. B. T. M. (2003), The effect of image enhancement on the statistical analysis of functional neuroimages: Wavelet-based denoising and Gaussian smoothing, in ‘Proc. SPIE: Medical Imaging’, Vol. 5032, pp. 1320–1330.

Wink, A. M. and Roerdink, J. B. T. M. (2004), ‘Denoising functional MR images: a comparison of wavelet denoising and Gaussian smoothing’, IEEE Transactions on Medical Imaging 23(3), 374–387.


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Publications in preparation: Wink, A. M. and Roerdink, J. B. T. M. (2005). Extracting the Haemodynamic Response Function using

Fourier-Wavelet Regularised Deconvolution. Wink, A. M. and Roerdink, J. B. T. M. (2005). Polyphase decompositions and shift-invariant wavelet

transforms in the frequency domain. Wink, A. M. and Roerdink, J. B. T. M. (2005). BOLD noise assumptions in fMRI.


Participation in the study program (attended Lectures, courses and conferences): 11/2002: InterGK Groningen (attendant) 7/2003: InterGK Oldenburg (attendant) 11/2003: InterGK Groningen (attendant) Regular attendance at BCN (mini-) symposia Regular attendance at Computer Science colloquia (Groningen) Compulsory BCN courses (BCN Orientation course, BCN poster presentation, BCN




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Dr. Huan Zhou, Carl von Ossietzky Universität Oldenburg

H2 and H8 Optimal Design of Multirate Filter Bank Systems

Thesis supervisor: Prof. Lihua Xie; EEE School, Nanyang Technological University, Singapore

InterGK supervisor: Prof. Alfred Mertins, Univ. Oldenburg

A systematic approach to a multi-objective filter bank design has been exploited. Different from conventional filter bank design approaches, the filter bank systems are studied from a novel periodic system viewpoint. We studied channel deconvolution (channel equalization) issue in noisy communication channels. In addition, subband coding systems, which are commonly used for the spectral decomposition in audio coding, are mainly investigated. In addition to satisfying performance on signal fidelity, additional requirements on linear phase and noise shaping, etc. can also be satisfied simultaneously. The results are further extended to robust multi-user communication system design.

Thesis period: 2000-2004

Financial Aid in Nanyang Technological University (Singapore): Mar. 2000 ~ Sep.2003, Financial Aid in International Graduate School: Feb. 2004 ~ May.2004 (Ph.D. stipend), June 2004 – Jan. 2005 (PostDoc stipend)

Publications and Lectures: Zhou,H. Mertins,A. Strahl,S. An Efficient, Fine-Grain Scalable Audio Compression Scheme 118th

Audio Engineering Society Convention, Barcelona Spain (2005), Preprint No. 6435. H. Zhou (2003), “Optimal Bit-Rate Allocation and Synthesis Filter Bank Design for Multirate Subband

Coding Systems”, Proc. IEEE ICASSP, VI_105-VI_108. H. Zhou (2002) “A Direct Approach to H2 Optimal Deconvolution of Periodic Digital Channels”, IEEE.

Trans. on Signal Processing. Vol.50, 1685-1698 H. Zhou (2001) “H2 Optimal Deconvolution of Periodic IIR Channels: an LMI Approach”, Proc. IEEE

ISSPA, Vol.1, 76-79. H. Zhou (2001) “Optimal Deconvolution of Periodic Systems with Application to Multirate Filter Bank

Design”, Proc. ICICS, Vol.1, 13-16.. Strahl,S. Zhou,H. Mertins,A. An Adaptive Tree-Based Progressive Audio Compression Scheme IEEE

Workshop on Applications of Signal Processing to Audio and Acoustics, New Paltz, NY (2005) – submitted/accepted

Publications in preparation: H. Zhou, “Design of Transmultiplexer Systems with Crosstalk Attenuation Constraint”, accepted, to

appear on EURASIP Journal on Applied Signal Processing. H. Zhou, “Robust and Optimal Mixed H2 /H? Design of Transmultiplexer Systems”, submitted to IEEE

Trans. On Communications (under revision). H. Zhou, “Joint Optimization of Bit-Rate Allocation and Synthesis Filter Bank for Multirate Subband

Coding Systems”, submitted to IEEE Trans. on Circuits and System I. Theory & System (under revision).


Dissertation project Stephan Strahl, Hearing Aid Algorithm research (group B. Kollmeier)


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Participation in the study program (attended lectures, courses and conferences): Jul. ~ Dec. Digital Signal Processing weekly colloquium of the InterGK, Oldenburg monthly meetings of the InterGK in Groningen and Oldenburg summer school of the InterGK “Object perception: physiology, psychophysics and

models”, 2004, Bad Zwischenahn


Occupation after leaving the graduate school (if applicable): Postdoctoral Fellow (InterGK)/ R&D Engineer, Audio Video Systems Team, Panasonice Singapore Laboratories Pte Ltd, Singapore


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Dipl.-Biol. Melanie Zokoll, Carl von Ossietzky Universität Oldenburg

Auditory memory in songbirds and humans

Thesis supervisor: Georg Klump, Ulrike Langemann, Zoophysiologie und Verhalten

To evaluate a sequence of acoustic communication signals it is necessary to keep the previous elements in memory. This not only applies to the analysis of speech by a human observer, but also to the analysis of a long sequence of elements in the song of a bird. Female European starlings (Sturnus vulgaris), for example, base their mate choice on the diversity of elements that an individual male sings (Eens et al. 1991). To access the diversity of elements that a female hears in a song she needs to store information about the elements in short-term memory. Thus, starlings should be suitable models to investigate the role and mechanisms of auditory short-term memory. The aim of my dissertation project is to measure the persistence and capacity of auditory short-term memory stores in the European starling and to compare these data with self collected human data, obtained under similar conditions. These animal experiments can thereby contribute to clarify the universal validity of existing (short-term) memory concepts, which are often explicitly language-related (e.g. Baddeley, 2003).

In experiments completed to date, I have applied a delayed-non-matching-to-sample (DNMTS) paradigm to estimate the persistence of the short-term memory stores. The starlings were trained in a Go/NoGo procedure. After initiating a trial by pecking an observation key, the birds are presented with a series of up to 6 identical sample tones and a final test tone with random inter-stimulus intervals. The characteristics of the test tone are either the same as those of the sample tones (NoGo-Stimulus) or they are different (Go-Stimulus). With presentation of a Go-stimulus the starling has to peck a report key, which results in a food reward. Memory performance can be obtained as the proportion of correct responses in relation to the total number of pairs of sample and test stimuli that have been presented with a specific delay (e.g. Kojima, 1985; Kowalska, 1997). The persistence of short-term memory is measured as a function of the delay between the last sample and the test. Completed experiments with sinusoidal stimulus signals resulted in short-term memory persistence times of between 4 and 20 s. In comparison to other bird species the European starling seems to have rather long auditory short-term memory persistence times (e.g. Budgerigar (Melopsittacus undulates): Downing et al. 1988: approximately 0.45 s) and seem to be in a similar range as observed in humans (e.g. Clément et al. 1999; Cowan, 1997). I also found a positive interrelation between short-term memory performance and sample series size as well as short-term memory performance and salience of the difference between sample and test stimulus. The results of these experiments are currently being written up for publication.

I am also investigating the possible dependence of the starlings’ short-term memory duration on stimulus complexity in two additional experiments. In the first of these experiments, the stimuli consist of complex amplitude-modulated broadband noise stimuli and will provide for a direct comparison to the results of the previously described experiment, which used simple, sinusoidal tones as stimuli. In the second experiment I will use biologically meaningful and information-carrying song motifs. Because song is the primary form of communication in songbirds, the results of this


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experiment will provide a basis for comparisons to human studies of short-term auditory memory for speech sounds. These two experiments will result in independent publications.

In an additional part of my doctoral thesis I will measure the capacity of the starlings’ auditory memory using a serial probe recognition task. The birds will be trained to compare a sequence of different sample stimuli with an additional test stimulus presented with certain delays, and to indicate in a Go/NoGo procedure if the test stimulus has been presented in the recently attended sequence or not.

References: Baddeley, A (2003) „Working memory: looking back and looking forward”, Nat. Rev. Neurosci. 4: 829-

839 Clément S, Demany L, Semal C (1999) „Memory for pitch versus memory for loudness”, J. Acoust.

Soc. Am. 106: 2805-2811 Cowan, N (1997) „Attention and memory: An integrated framework”, Oxford U.P., NY Downing JD, Okanoya K, Dooling RJ (1988) „Auditory short-term memory in the budgerigar

(Melopsittacus undulatus)”, Anim. Learn. Behav. 16: 153-156 Eens M, Pinxten, R, Verheyen RF (1991) „Male song as a cue for mate choice in the European

starling”, Behav. 116: 210-238 Kojima, S (1985) „Auditory short-term memory in the Japanese monkey”, Intern. J. Neurosci. 25: 255-

262 Kowalska, DM 1997 „The method of training dogs in auditory recognition memory tasks with trial-

unique stimuli”, Acta Neurobiol. Exp. 57: 345-352

Thesis period: April 8th, 2003 – April 7th, 2006 (projected)

Publications and Lectures: Langemann U, Zokoll MA, Klump, GM (in press) „Analysis of spectral shape in the barn owl auditory

system”, J. Comp. Physiol. A. Zokoll, MA, Langemann, U, Klump, GM (2004) „Profile analysis in the barn owl (Tyto alba)”, Abstr.

Assoc. Res. Otolaryngol. 27 Zokoll, MA, Langemann, U, Klump, GM (2005) „Auditory short-term memory for tonal signals in a

songbird”, Abstr. Assoc. Res. Otolaryngol. 28

Publications in preparation: Zokoll, MA, Langemann, U, Klump, GM (2006) „Auditory short-term memory for tonal signals in a

songbird“, in preparation for J. Acoust. Soc. Am.

Cooperation with and/or relation to other projects: There is an exchange of experimental methods and software development amongst other psychoacoustics projects (Karin Klink, Julia Maier). Stefan Strahl programmed a MATLAB tool that produces the matrices for the experiments in this project. Moreover there is a fertile interaction with Rike Steenken concerning the basic theories of cognitive functions.

Participation in the study program (attended lectures, courses and conferences): Physikalische Akustik, 2004/05, FH Oldenburg Regularly: Seminar of the international graduate school „Neurosensory science and

systems“ , Oldenburg, Germany and Groningen, Netherlands Regularly: Seminar of the zoophysiology and behavior group, Oldenburg, Germany Non regularly: Neurobiological seminar of the institute of biology and environmental

sciences, Oldenburg, Germany 09/2003: Block course „Psychophysik und Neurosensorik”, Oldenburg, Germany


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05/2003: „Meeting of the European Graduate School for Neurosensory Science and Systems and the Graduate School of Neuroscience”, Copenhagen, Denmark (Poster presented)

06/2004: Meeting with Tübinger GKKN, Tübingen, Germany (Poster presented) 09/2003: BCN EGK Summerschool „Parallels in visual and auditory processing”,

Odoorn, Netherlands (Poster presented) 03/2005: Meeting with Tübinger GKKN, Oldenburg, Germany (Poster presented) 08/2005: Summerschool „Object formation in audition and vision: Bottom-up and top-

down processes”, Bad Zwischenahn, Germany (Poster presented) 06/2003: 29th Göttingen Neurobiology conference, Göttingen, Germany 02/2004: ARO, Daytona Beach, FL, USA 02/2005: ARO, New Orleans, LA, USA

Teaching/supervision/ counseling within the graduate school: 10-11/2004: Advanced internship (V-Praktikum) „Einfluß von Stimuluswieder-

holungen in Kurzzeitgedächtnis-Aufgaben bei Staren (Sturnus vulgaris)“ 05-08/2005: Participation in the Risearch Internships in Science and Engeneering

(RISE)-program of the German Academic Exchange Service (DAAD) „Memory Project”



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REPORT OF POSTDOCTORAL FELLOWS

Dr Annika Åkerfelt, Carl von Ossietzky Universität Oldenburg

Visual-Tactile Stop Signal Inhibition

Description of college-specific tasks: Preparation of articles for publication, Speaker of the Ph.D. students SS2003

Publications and lectures:

Publications in preparation: Åkerfelt, A., Colonius, H., Diederich, A. (submitted). "Visual-tactile saccadic inhibition", Experimental

Brain Research Åkerfelt, A., Sams, M., Jääskeläinen, I., Klucharev, V. (in preparation) "Evoked responses to visual-

tactile stop signal inhibition"

List of stays abroad:


Occupation after leaving the graduate school: Science Editor, GreenFacts asbl/vzw, Brussels, Belgium


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Dr. Jörn Anemüller, Carl von Ossietzky Universität Oldenburg

Blind Source Separation in speech, EEG, and fMRI

In July 2001, I finished my Ph.D. studies in the medical physics group, University of Oldenburg, with a thesis on independent component analysis applied to speech signals, entitled "Across-frequency processing in convolutive blind source separation".

After a brief postdoc period in Oldenburg, I moved to the United States where I worked as a postdoctoral scholar from November 2001 to September 2004 at the Computational Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, and at the Swartz Center for Computational Neuroscience, University of California San Diego, La Jolla, California.

During this time, I was supported by the Salk Institute for Biological Studies, the German Academic Exchange Service (DAAD), the German Research Council (DFG), and the Swartz Foundation.

The focus of my work moved from speech signal processing to analysis of brain signals, in particular electroencephalographic (EEG) and functional magnetic resonance imaging (fMRI) data.

Analysis of these neuroscience data was carried out using statistical signal processing algorithms that I developed and which were based on the work during my Ph.D. studies.

The desire to make use of such signal processing techniques in the field of neuroscience required a significant further development of the algorithms, while at the same time using an understanding of the underlying biological processes to identify the relevant parts of information that should be modeled quantitatively and to evaluate the plausibility and compatibility of numerical results obtained with known physiology.

This goal could only be achieved by closely collaborating with experimental practitioners, which I was fortunately given the opportunity to do.

During this time, I took great advantage of the knowledge that I had acquired through the graduate school in Oldenburg, which introduced me not only to my own field of signal analysis, but also brought me in contact with graduates of other disciplines.

In particular, the grasp of EEG and fMRI experiments I acquired within the graduate school was of large value when searching for a postdoctoral position and when starting research in the neuroscience field.

Therefore, I am very grateful to the successful interdisciplinary approach to learning and thinking within the graduate school.

Since October 2004, I am working as a member of the scientific staff in the medical physics group, University of Oldenburg, conducting research in statistical data analysis with a focus on speech modeling, speech recognition and neuroscience data.

Publications and lectures: J. Anemüller, J.-R. Duann, T. J. Sejnowski, and S. Makeig. Spatio-temporal dynamics in fMRI

recordings revealed with complex independent component analysis, Neurocomputing, accepted for publication, 2005.


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J. Anemüller, J.-R. Duann, T. J. Sejnowski, and S. Makeig. Unraveling spatio-temporal dynamics in fMRI recordings using complex ICA. 5th International Conference on Independent Component Analysis and Blind Signal Separation, pages 1103-1110 , Granada, Spain, September 2004.

J. Anemüller, T. J. Sejnowski, and S. Makeig. Reliable Measurement of Cortical Flow Patterns using Complex Independent Component Analysis of Electroencephalographic Signals. 5th International Conference on Independent Component Analysis and Blind Signal Separation, pages 1009-1016, Granada, Spain, September 2004.

J. Anemüller, T. J. Sejnowski, and S. Makeig. Complex independent component analysis of frequency-domain electroencephalographic data. Neural Networks, 16:1311-1323, 2003.

J. Anemüller, T. J. Sejnowski, and S. Makeig. Complex spectral-domain independent component analysis of electroencephalographic data. In Proceedings of the fourth international workshop on independent component analysis and blind signal separation, pages 47-52, Nara, Japan, 2003.

J. Anemüller and B. Kollmeier. Adaptive separation of acoustic sources for anechoic conditions: A constrained frequency domain approach. Speech Communication, 39(1-2):79-95, Jan 2003.

List of stays abroad: USA 2001 - 2004


Occupation after leaving the graduate school (if applicable): Postdoctoral fellow, The Salk Institute for Biological Studies, La Jolla, California,

Research associate, Medizinische Physik, Universität Oldenburg


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Dr. Petra Arndt, Carl von Ossietzky Universität Oldenburg

Movement control under multisensory stimulation

My postdoctoral research aims to find an explanation for the principles of sensory-motor integration under multimodal stimulation and thus to contribute to an understanding of the involved processes. We selected two different motor systems to avoid a too restricted structure-centered view on sensory-motor processes. Our examination has included saccadic eye movement and goal-directed hand movement (pointing movements as a rule). An accordance of the underlying neuronal mechanisms in the sense of a common motor control of spatial and/or temporal movement parameters is controversially discussed. The investigation of this issue is a main purpose of my studies.

The current literature reveals a number of inconsistent experimental findings. The experimental studies I have carried out differ from those conducted by other working groups, because we used multimodal, visual-auditory stimuli. A comparison of the rules underlying intersensory interaction in the control of saccades and directed movements permits to draw conclusions on the likelihood of common control processes. The experiments reported here investigate different aspects of the mechanisms we investigate.

Intersensory interaction and sensory-motor integration, effects of spatio-temporal stimulus arrangement The effects of multisensory, visual-auditory integration processes on eye and arm movement control are analyzed in order to gain further insight in the respective motor control processes. If eye and arm movements share processes based on the same multimodal representation of sensory stimuli, then experimental manipulations of the bimodal stimulus arrangement should reveal equivalent effects for both movements. The basis for this approach is, that in the superior colliculus, a central structure in eye movement control, multimodal, visual-auditory neurons were found as well as arm-movement-related neurons (Meredith & Stein, (1986),Werner et al., 1997b).

We conducted psychophysical experiments using a focussed attention paradigm. Subjects were asked to respond to a visual target stimulus with a saccadic eye movement, a goal directed hand movement or both and to ignore an accessory auditory stimulus. Latencies and error rates were used as measure of visual-auditory interaction. In a first experiment the temporal and spatial relationship between target and accessory stimulus were varied. Visual targets (white dots) were presented on a black computer screen at eccentricities of 15. or 25. to the left or to the right of the .xation point. Broadband noise signals were presented as auditory accessory stimuli 30 ms prior to the visual stimulus, simultaneously, or 60 or 120 ms after the onset of the visual target. The noise signal was presented at five different spatial positions (straight ahead, 15. or 30. to the left or to the right) in a virtual acoustic environment.

The dependence of latencies on spatio-temporal stimulus arrangement was similar for eye and arm movements. Latencies were reduced by accessory auditory stimulation for both movement types. The reduction was the stronger the earlier the accessory was presented and the smaller the spatial distance between target and accessory. However, hand movement latencies showed a markedly stronger dependence particularly on spatial stimulus variation. Moreover we observed


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markedly more directional errors in hand movements compared to eye movements - even when both movements had been performed simultaneously.

Our results suggests a stronger influence of the auditory stimulus on manual latencies and therewith contradict the hypothesis that eye and arm movements share common motor commands.

Intersensory interaction and sensory-motor integration, effects of stimulus intensity As a further test for this interpretation of our data we varied the intensity of the accessory stimulus in a second experiment. Given the e.ect of the auditory on manual reaction times is stronger than on eye movements we expect a stronger dependence of the former on intensity variation. Auditory stimulus intensities were presented at three different intensity levels separated by steps of 6 dB. The absolute intensity was determined individually for each subject. As in the first experiment white dots and broadband noise signals were used as stimuli. Possible stimulus positions were 25 deg. to the left and to the right of the fixation point for both stimuli and additionally straight ahead for the auditory stimulus. Visual target and auditory signal were always presented simultaneously.

As in the first experiment the spatial variation in stimulus arrangement led to stronger effects on manual latencies compared to saccadic latencies. However, the latencies for both types of movement decreased with increasing auditory intensity in a similar manner. There was no evidence of a stronger effect of auditory intensity on arm movements.

Dynamic sensory processing is mirrored in multisensory interaction The apparent contradiction may be evoked by the fact that manual latencies are longer (by about 100 ms) than saccadic latencies. This might allow for a longer processing of the auditory signal resulting in different spatio-temporal effects. While the position of a visual signal is derived from retinal coordinates relatively directly, the localization of an auditory signal requires the processing of small interaural time and intensity differences. This process is time consuming and it is assumed that first a rough estimate of auditory position is made which is re.ned subsequently (Hofmann and Van Opstal, 1998). In contrast to the location the intensity on an auditory stimulus is available to the auditory system early on. Thus possibly manual movements and saccades rely in fact on a shared representation of the visual-auditory environment, but due to the differences in latencies the point in time when the spatial information is retrieved differs between both movements. During this time the localization of the auditory signal may be improved leading to a finer ”spatial tuning”.

To test this hypothesis we varied the temporal stimulus arrangement over a wide range (300ms). To avoid any unwanted effects of the virtual acoustical environment 1 we decided to conduct these experiments under free field conditions. Three loudspeakers were positioned 1 m in front of the subject at ear level.

Horizontal distance was 15deg. Red LEDs were mounted on top of the loudspeakers. The central LED served as fixation target. The auditory stimulus was presented at seven possible stimulus onset asynchronies (SOA) ranging between 50 ms prior to the visual onset up to 250 ms after the visual stimulus. Again the effects of spatio-temporal stimulus arrangement were different for hand compared to eye movements. Latency reduction for both movements was strongest when the auditory signal was given prior to the visual and approached the level of reaction times under unimodal, visual stimulation with increasing SOA. However, the facilitating effect of the


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accessory on eye movements levels of 100 to 150 ms earlier than for hand movements. Similarly the spatial effect diminishes with increasing SOA for saccades 50 to 100 ms earlier than for manual latencies. The latency curves appear ”shifted” with respect to each other.

These results provide support for the assumption that hand and eye movements are based on the same visual-auditory representation.

The spatial representation of stimuli again depends on dynamic localization processes and thus is not stable over time. This is particularly obvious in the auditory system, where detection, localization of horizontal position, and localization of vertical position are separate and independent processes. As a consequence the perceived position of an audito ry signal changes during the time course of auditory processing.

Our findings indicate that visual-auditory interaction is not based on completely processed unimodal stimuli. Rather the dynamic processes within the sensory systems are mirrored in the multisensory interaction directly.

Temporal decoupling in eye-hand coordination: Effects of task and stimulus. (in cooperation with Sandra Tabeling) It is known from the literature that directed pointing movements are more closely connected with eye movements than are reactions given by keypress, even if the task is designed in a way so that the keypress response presupposes a localization of the goal stimulus. To see whether this coherence is caused by either the larger amplitude of the pointing movement or the variability in the movement execution (trajectories), or whether – as postulated by Bekkering et al. (1995) – it is actually to be traced back to the fact that a goal-directed movement is carried out, we tested this question by using the following setting : The LEDs which we used as stimuli were positioned at a distance of about 3 cm from the marked resting position of the forefinger of the right and left hand. So the pointing movement to be given as response by which the LED was to be touched was similar to the normally used measurements through keypress. The test person was asked either to make an eye movement or the above mentioned pointing movement or the two movements at the same time.

The findings show clearly that even with very short, stereotype pointing movements the interference effects which are typical for the simultaneous execution of eye and pointing movements do occur: For all the test persons, saccadic latency is longer if a simultaneous hand movement is required. Additionally, for a proportion of the test persons pointing movements accompanied by saccades show significantly longer latencies than pointing movements without saccades which are simultaneously to be carried out. The interference effects between eye and hand, as known from the literature, are not caused by the fact that pointing movements are performed with high amplitude and an accordingly great liberty in the movement trajectory, but occur even with strongly restricted movements.

From our results we conclude that saccadic latencies decrease when the performance of the hand movement can be improved by prior fixation of the target whereas in other cases (e.g. large targets, auditory targets) a latency increase may appear. This increase in mean saccadic latency may be caused by those saccades which are elicited after the hand movements are executed.

Target modality affects rules of multisensory integration


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As can be seen from behavioural data the rules of multisensory integration are task dependent (Corneil und Munoz 1996, Arndt 2002). One example is the effect of target modality on intersensory integration. Behavioural data like reaction times and error rates change depending on target modality. As a possible neural basis for this task dependency van Opstal and Munoz (in press) discuss responses of fixation neurons in SC under different fixation conditions. However, this type of neurons is specific for the oculomotor system. Hence the task dependency in other motor systems, e.g. limb movements can be expected to differ from that in saccades if fixation neurons are involved in task dependency in the saccadic system.

To test this hypothesis we measured saccadic eye movements and goal directed hand movements towards visual and auditory target stimuli. Visual and auditory targets were presented either alone or with an auditory resp. visual accessory stimulus. Spatial and temporal relationship between target and accessory were varied. Three different response types, eye movements alone, hand movements alone and concomitant eye and hand movements, were measured in separate blocks in every session.

Strong intersensory facilitation effects have been found for visual target stimuli combined with accessory auditory stimuli. This holds true even if the auditory stimulus is presented after the visual stimulus. For these data sets a test for violation of the horse race inequality gave evidence for intersensory integration processes in eye movement but not in hand movement control. However, due to the structure of the test this does not rule out the possiblilty of intersensory integration in hand movements. In neither case intersensory inhibition was found, although physiological data from anaesthetised animals revealed strong inhibitory effects for spatially separate presentation of visual and auditory stimuli.

In contrast to visual target stimuli intersensory facilitation effects are weak for auditory targets in combination with visual accessory stimuli. Reductions of reaction times can be observed only if both stimuli are presented at the same spatial position and if the visual stimulus is presented before or at the same time as the auditory target stimulus. Further analysis is necessary to control whether this reduction may be evoked by erroneous responses towards the accessory stimulus. In all other spatial and temporal combinations intersensory inhibitions was found, similar as suggested by physiological data from SC (Meredith & Stein, 1993). The same overall pattern of inhibition and facilitation were found for saccadic eye movements and for limb movements when these movements were executed separately. This casts a significant role of eye fixation neurons in task dependency into doubt.

Preliminary conclusion The results of the first experiments seem to be as contradictory as the findings of several other investigators. However, more elaborated experimental designs made clear that the underlying mechanisms are based on dynamic processes. Taking this dynamics into account the contradiction can be resolved.

Taken together our results indicate that eye and arm movements are based on dynamic maps. Certain environmental factors like small targets, high precision requirements etc. lead to a fixed temporal order and to strong temporal coupling between both movements. In these cases dynamic processes play a minor role in the guidance of behaviour. In contrast more relaxed task requirements lead to lower temporal correlation of the movements Therewith dynamic processes influencing spatial aspects have the opportunity to influence behavioural parameters.


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Although this interpretation of the data explains the findings qualitatively, a quantitative description of the mechanisms described above is desirable. The next step in my project is to develop a model allowing for such a quantitative description.

Publications and lectures (last 5 years): Arndt, P.A. (2004). „Target Modality Affects Rules of Visual-Auditory Integration.” In: Dynamic

Perception, Uwe J. Ilg, Heinrich H. Bülthoff, Hanspeter A. Mallot (Hrsg.), Akademische Verlagsgesellschaft Aka, Berlin, S. 83-88

Arndt, P.A., Colonius, H. (2003). “Two stages in crossmodal saccadic integration: evidence from a visual-auditory focused attention task .” Exp Brain Res, 150, 417-426

Özyurt, J., Colonius, H., Arndt, P.A. (2003), “Countermanding saccades: Evidence against independent processing of go and stop signals.” Perception & Psychophysics 65: 420-428

Arndt, P.A. (2002). “Intersensory Interaction in Eye and Arm Movements.” In: Dynamic Perception, Rolf P. Würtz, Markus Lappe (Hrsg.), Akademische Verlagsgesellschaft Aka, Berlin, S. 303-308

Colonius, H., Arndt, P.A., (2001). “A Two-Stage Model For Visual-Auditory Interaction in Saccadic Latencies.” Perception and Psychophysics 63(1): 126-147

Colonius, H., Özyurt, J., Arndt, P.A.(2001). “Countermanding saccades with auditory stop signals: testing the race model.” Vision Research 41: 1951-1968

Colonius, H., Arndt, P.A. (1999). “The effect of auditory distractors on saccades to visual targets.” A comment on “A model of saccade generation based on parallel processing and competitive inhibition” by J. M. Findlay & R. Walker. Behavioral and Brain Science 22: 677-678.

Publications in preparation: Arndt, P.A., Tabeling, S. (in Vorbereitung). Are saccades facilitated or inhibited by concomitant arm

movements?


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Dr. Mark Allen Bee, Carl von Ossietzky Universität Oldenburg

Object Perception: Neural Mechanisms of Auditory Scene Analysis in the European Starling (Sturnus vulgaris)

The principal objective of my work has been to identify low-level, pre-attentive auditory processes that contribute to the formation of perceptual auditory objects and the segregation of these objects from background masking noise. The project has focused on electrophysiological experiments in a songbird model system, the European starling (Sturnus vulgaris). I used radio telemetry to record neural activity in the auditory forebrains (field L2) of awake starlings in response to stimulus conditions for which perceptual data from this species are already available to address two major goals.

One goal of this project was to identify low-level, pre-attentive mechanisms involved in the perceptual segregation of simple interleaved tone sequences, which has been studied in humans and starlings using sequences of two alternating tones differing in frequency (e.g., ABA-ABA-ABA-. . .). The segregation of A and B tones into separate auditory streams (the so-called “streaming effect”) is believed to be promoted by pre-attentive auditory processes that increase the separation of excitation patterns along a tonotopic gradient. We have tested the hypothesis that frequency selectivity and forward masking operate as two pre-attentive processes in sequential stream segregation by recording neural responses in the auditory forebrain of awake starlings to repeated ABA-… or ABAB… sequences in which we varied the frequency separation (? F) between the A and B tones and various timing intervals between tones (Bee and Klump, 2004, in press). At present, our physiological results are not entirely consistent with expectations from human psychophysical data on the streaming effect, although these differences may reflect the operation of different segregation versus integration processes occurring at different levels of the auditory system. Additional psychophysical studies of starlings and humans, and perceptual and physiological studies in other species, such as primates, will be necessary to determine the source of these inconsistencies.

A second goal of the project has been to investigate the sensory mechanisms of masking release by determining how low-level auditory processes segregate temporally modulated signals from temporally modulated maskers. One example of this phenomenon involves an “asymmetry of masking” that is related to relative differences in the bandwidths of signals and maskers. Signals and maskers that differ in bandwidth also differ in the frequencies of temporal fluctuations in their amplitude envelopes. Detection of a signal with a particular center frequency is improved when its bandwidth exceeds that of a masker with the same center frequency compared to a condition in which bandwidths of the signal and masker are reversed, even when the bandwidths of both the signal and masker are less than the width of the critical-band filter centered at the frequency of the signal and masker. Such findings have led to the suggestion that the auditory system can rely on differences in the temporal modulation frequencies of signals and maskers to improve signal detection. I have investigated the neural correlates of asymmetry of masking using signals and maskers with center frequencies that were the same as the CF of the recording site and had the same bandwidths (4 Hz and 256 Hz, fully factorial design) that were used in a perceptual study of asymmetry of masking in starlings by Langemann and Klump (submitted). Our findings suggest that the neural


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responses thresholds are lower for detecting a 256-Hz-wide noise in a 4-Hz-wide masker than for the opposite condition of detecting a 4-Hz-wide noise in a 256-Hz-wide masker. In other words, auditory forebrain neurons exhibit a similar asymmetry of masking as found in perceptual studies of both starlings and humans. I am currently working with Jesko Verhey (Carl von Ossietzky Universität) to incorporate these results into a general model of temporal modulation processing (Bee et al. in preparation a).

A second example of the importance of temporal modulation processing comes from studies of comodulation detection difference (CDD), a phenomenon in which temporal correlations across the frequency spectrum of a masker can be exploited to improve the detection of signals that are not spectrally masked but have different temporal envelopes than masker flanking bands. In the case of CDD, humans and starlings (Langemann & Klump in preparation) have lower signal detection thresholds for detecting an amplitude modulated narrow-band noise when separate flanking noise bands at different parts of the spectrum have temporally correlated envelopes that differ from that of the signal compared to conditions in which the signal and flanking bands all have the same envelope or different envelopes. In other words, the auditory system is better able to perceptually segregate a signal from noise when the noise has temporally correlated, or “comodulated” envelopes across the spectrum that differ from that of the signal.

My work with Prof. Dr. Georg Klump seeks to explain the perceptual CDD effect known from humans and starlings at the level of neural mechanisms. I have recently found that starling auditory forebrain neurons exhibit similar patterns of CDD as demonstrated in starling perceptual tests (Bee et al. in preparation b). Our data suggest that the CDD effect can be explained largely by the operation of within-channel temporal processing mechanisms. This result is of some theoretical importance, because there is ongoing debate about the relative contributions of within-channel and across-channel processing in studies of CDD. Based on my work, and in collaboration with Michael Buschermöhle, Jan Freund, and Ulrike Feudel, we are developing a theoretical model (Buschermöhle et al., submitted; Bee et al. in preparation b) that seeks to explain our physiological findings in as widely an applicable model as possible based on a peripheral non-linearity and peripheral filtering.

Description of college-specific tasks: Native American speaker/ proofreader for publications

Publications and lectures: (a) Invited Book Chapters and Contributions to Edited Volumes Gerhardt H.C. and Bee M.A. (in press) “Recognition and localization of acoustic signals” In: Hearing

and Sound Communication in Amphibians (eds. Feng AS and Narins PM), Springer Handbook of Auditory Research. Springer: New York.

Bee M.A. (in press) “Animal communication: Social and individual recognition in animal species.” In: The Encyclopedia of Language and Linguistics: Volume 2 (section editor, Naguib M), Elsevier Science.

(b) Peer-reviewed Publications Bee M.A. and Klump G.M. (in press) “Auditory stream segregation in the songbird forebrain: Effects

of time intervals in responses to interleaved tone sequences” Brain, Behavior and Evolution. Bee M.A. and Klump G.M. (2004) “Primitive auditory stream segregation: A neurophysiological study

in the songbird forebrain” Journal of Neurophysiology, 92, 1088-1104. (c) Published Abstracts Langemann U., Bee M.A., and Klump G.M. (2005) “Comodulation effects in a songbird:

Comodulation detection difference” Association for Research in Otolaryngology Abstract: 721.


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Bee M.A., Langemann U., and Klump G.M. (2004) “Asymmetry of masking: A psychophysical and physiological study in the European starling” Association for Research in Otolaryngology Abstract: 314.

Klump G.M., Bee M.A., Hofer S.B., and Langemann U. (2004) “Mechanisms of Auditory Scene Analysis” In: 7th Tübingen Perception Conference (Bülthoff HH, Mallot HA, Ulrich RD, and Wichmann FA, eds) Knirsch Verlag, Kirchentellinsfurt.

(d) Invited Symposium Presentations Bee M.A. and Klump G.M. (2005) “Auditory stream segregation: Neurophysiological perspectives

from the songbird forebrain” 31st Deutsche Jahrestagung für Akustik, DAGA '05, Munich, Germany, March 14-17, 2005.

(e) Invited Seminars Universität Bielefeld Universität Hannover Universität Tübingen North Carolina State University University of Minnesota University of Newcastle Upon Tyne Humboldt-Universität zu Berlin University of Cambridge Dartmouth College

Publications in preparation: Buschermöhle M., Feudel U., Bee M.A., Klump G.M., and Freund J. (submitted) “Signal detection in

comodulated noise” Physical Review Letters Bee M.A. Verhey J.L., and Klump G.M. (in preparation a) “Asymmetry of masking in the European

starling: II. Neural auditory thresholds” To be submitted to Nature Neuroscience. Bee M.A., Buschermöhle M., Feudel U., Freund J., and Klump G.M. (in preparation b) “Comodulation

detection differences in starlings: II. Neural mechanisms for segregating modulated signals from modulated noise” To be submitted to European Journal of Neuroscience.

Miller C.T. and Bee M.A. (in preparation) “Animal vocal communication: From signals to systems” To be submitted to Animal Behaviour


Occupation after leaving the graduate school (if applicable): Assistant Professor Department of Ecology, Evolution and Behavior University of Minnesota


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Dr. ir. Gerke Hoiting, Carl von Ossietzky Universität Oldenburg

Active noise reduction in MRI

The goal of this project is to reduce the acoustic noise from the MRI scanner through active noise cancellation (ANC). With a headphone, the noise from the scanner is played in anti-phase. In a perfect situation, the sounds from headphone and scanner cancel out.

Until this point, a firm theoretical background is laid on this topic including a mathematical approach. Pitfalls and oppurtunities are characterised and preliminary results are obtained. Although promising results are obtained in a laboratory setting, the results in the scanner environment still pose difficulties. Further development of apparatus has to be done and improving accuracy (amplitude and phase characteristics) of the ANC system will lead to better results.

While the subject is lying in the sound source (the MRI scanner), the bone conduction may play an important role. This has to be explored further.

Description of college-specific tasks: Transfer of knowledge from Groningen to Oldenburg

Publications in preparation: Hoiting, G, and Duishuis, H (2005). „Predicting Sound Pressure Levels in MRI“, in preparation for IEEE

Transactions on Medical Imaging Hoiting, G, and Duishuis, H (2005). „Reducing Sound Pressure Levels in MRI – a review”

List of stays abroad: 4/2005 –4/2005 Rijksuniversiteit Groningen, Groningen, The Netherlands


Occupation after leaving the graduate school (if applicable): Postdoctoral fellow, RU Groningen


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Dr. rer. nat. Manfred Mauermann, Carl von Ossietzky Universität Oldenburg

Fine Structure in Distortion Product Otoacoustic Emissions and Auditory Perception

Thesis supervisor: Prof. Dr. Dr. Birger Kollmeier, Medizinische Physik)

Otoacoustic emissions (OAE) are sounds emitted from a healthy ear and can be recorded in the sealed ear canal. The measurement of otoacoustic emissions is well established as a tool for hearing screening. However, until now OAE measurements allow no precise individual prediction of hearing status. The aim of the dissertation project was to increase the basic understanding of distortion-product-otoacoustic-emission (DPOAE) generation and so to increase the value of DPOAE measurements as a diagnostic tool. In two chapters the results from experiments and modeling of properties of DPOAE-fine structure in normal hearing and hearing impaired subjects give strong evidences for a second DPOAE source within the cochlea. Additional results showed that the influence of the second source increases with decreasing stimulation level. Furthermore, it is shown that the variability of DPOAE I/O functions and predictions of hearing thresholds, derived from these, is drastically reduced if the second DPOAE source is cancelled out. Finally the psychoacoustical side of the problem was investigated. Pure tone thresholds and loudness perception of sinusoids show a pronounced fine structure across frequency with level difference of up to 15 dB. These results are relevant for the comparison of DPOAE and psychoacoustical measurements as well as for the basic understanding of loudness perception near threshold in principle.

State of the dissertation project: completed

Thesis period: Start of graduation: Jan. 1998; Defense of thesis: Feb. 2004; Interception of graduation project from Jan. 2001 - Feb. 2002 (during this period: position as “wissenschaftlicher Mitarbeiter“ at the University of Applied Science OOW)

Project: Temporal properties of loudness perception -differences in loudness of tone complexes with positive und negative Schroeder phase Tone complexes with positive (m+) and negative Schroeder phase (m-) have an identical long-term spectrum, the same temporal envelope but are inverted in time. They show large differences in masking efficiency most probably being related to a different cochlear representation. The current study investigates to which extent loudness perception is affected similarly by the different phase characteristic of m+/m- stimuli. In normal hearing subjects the m+ stimuli for certain fundamental frequencies need a 6 dB higher level to be perceived as equally loud as the respective m- stimuli. The largest differences in loudness between m+ and m- were found for levels between 40-60 dB, clearly reduced for higher and lower levels – indicating a different influence of compression on the different cochlear representation of the stimuli.

Project: Psychophysics and audiology of cochlear-fine structure – basic principles and applications for the early detection of hearing loss


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The threshold in quiet show a pronounced spectral fine structure in most normal hearing subjects, i.e., the threshold level varies quasi-periodically across frequencies with up to 15 dB. The fine structure of hearing threshold is vulnerable to high doses of Aspirin. Similar, fine structure in distortion product otoacoustic emissions is highly sensitive to cochlear damage after a sudden hearing loss. The first topic of the current project focuses on details of the influence of threshold fine structure on several psychoacoustic tasks like modulation detection, compression, loudness summation and integration. The second topic is to clarify whether cochlear fine structure is an indicator for a healthier and more sensitive cochlea or a highly vulnerable/pre-damaged ear. Furthermore it will be investigated if certain psychoacoustical or otoacoustic-emission measurements of fine structure related effects can be used as tool to distinguish vulnerable/pre-damaged from healthy cochleae.

Description of college-specific tasks: Co-supervisor of Stephan Heise (PhD student).

Publications (2002-2005): Dissertation Mauermann, M. (2004), "Fine Structure in Distortion Product Otoacoustic Emissions and Auditory

Perception." Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.

Journal articles Mauermann, M., Long, G. R., Kollmeier, B. (2004), "Fine structure of hearing threshold and loudness

perception." J. Acoust. Soc. Am., 116, p. 1066-1080. Mauermann, M., Kollmeier, B. (2004), "Distortion product otoacoustic emission (DPOAE) input/output

functions and the influence of the second DPOAE source." J. Acoust. Soc. Am., 116, p. 2199-2212.

Müller-Wehlau, M., Mauermann, M., Dau, T., Kollmeier, B. (2005), "The effects of neural synchronization and peripheral compression on the acoustic-reflex threshold." J. Acoust. Soc. Am. 117, p. 3016-3027

Proceedings Mauermann, M., Kollmeier, B. (2003), "Wachstumsfunktionen lantenzgefilterter DPOAE bei

Normalhörenden." In 6. Jahrestagung der Deutschen Gesellschaft für Audiologie - Abstracts (DGA), März 2003, Würzburg, p. 17

Mauermann, M., Kollmeier, B. (2004), "Input-Output Functions from single Source Distortion Product Otoacoustic Emissions." Assoc Res Otolaryngol Abs, 27, p. 33.

Mauermann, M., Hohmann, V. (2005), "Differences in loudness of tone complexes with positive and negative Schroeder phase" J. Acoust. Soc. Am., 117, p. 2597.

Mauermann, M. (2005), "Vergleich von Methoden zur Messung der Hörschwelle mit hoher Frequenzauflösung." In 8. Jahrestagung der Deutschen Gesellschaft für Audiologie - Abstracts (DGA), Februar 2003, Göttingen, p. 82.

Mauermann, M., Hohmann, V. (2005), "Unterschiede in der Lautheitswahrnehmung von Tonkomplexen mit positiver und negativer Schroederphase." In 8. Jahrestagung der Deutschen Gesellschaft für Audiologie - Abstracts (DGA), Februar 2003, Göttingen, p. 84.

Mauermann, M., Kollmeier, B. (2005), "Einfluss der Kalibriermethode auf Wachstumsfunktionen otoakustischer Verzerrungsprodukte." In 8. Jahrestagung der Deutschen Gesellschaft für Audiologie - Abstracts (DGA), Februar 2003, Göttingen, p. 110.

Müller-Wehlau, M., Mauermann, M., Kollmeier, B. (2002), "Auswertealgorithmen zur Niedrigpegel-Reflexaudiometrie." In Fortschritte der Akustik - DAGA 2002, editor: Jekosch, DEGA e.V., Oldenburg, Bochum, p. 52-53.

Müller-Wehlau, M., Mauermann, M., Dau, T., Kollmeier, B. (2003), "Änderung der Stapediusreflexschwelle bei Kompensation der Basilarmembrandispersion durch Stimulation mit phasenoptimierten Tonkomplexen." In 6. Jahrestagung der Deutschen Gesellschaft für Audiologie (DGA), März 2003, Zeitschrift für Audiologie/Audiological Acoustics, Würzburg, p. 81.

Müller-Wehlau, M., Mauermann, M., Dau, T., Kollmeier, B. (2004), "Acoustic reflex thresholds obtained with chirp stimuli compensating for cochlear dispersion." Assoc. Res. Otolaryngol. Abs., 27, p. 309.


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Publications in preparation: Mauermann, M., Hohmann, V. (2005), "Differences in loudness of tone complexes with positive and

negative Schroeder phase" in preparation for J. Acoust. Soc. Am. Mauermann, M., Kollmeier, B. (2005), “Acceptable suppressor levels to eliminate the second DPOAE

source” in preparation for J. Acoust. Soc. Am.

Cooperation with and/or relation to other projects Inter GK Dr. J. Verhey, Universität Oldenburg (fine structure) Dr. V. Hohmann, Universität Oldenburg (temporal properties of loudness perception) Prof. H. Duifhuis, RUG, Groningen, Netherlands (cochlear modeling)

External Prof. Long, G. R., City University, New York, USA (DPOAE, fine structure) Dr. Carrick Talmadge, University of Mississippi, Oxford, USA (cochlear modeling) Dr. H. Maier, Uni-Klinikum Eppendorf, Hamburg (acoustic reflex, fine structure) Dr. U. Baumann, LMU, München, (acoustic reflex, fine structure)

Age when entering the graduate school:

32 (as associate member)

Occupation after leaving the graduate school (if applicable): Research associate (wissenschaftlicher Mitarbeiter) at the “Medizinische Physik“ group, Universität Oldenburg.


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Dr. Mark Pottek, Neurobiology, University of Oldenburg

Adaptational processes of the mammalian retina

(1) Retinoic acid as a retinal neuromodulator

The visual system exerts a suitable sensitivity over an extended range of light intensities which is achieved by a fine tuning of the neuronal pathways. Thereby, adaptation of the retinal circuits is attained by chemical messengers whose endogenous presence depends on the respective ambient light conditions. Yet, the properties of the known messengers are not sufficient to explain the full range of processes observed during retinal adaptation to changing light levels. This nourishes the search for additional modulators. Due to its well-known bioactivity (Dräger & McCaffery, 1997, Prog. Retinal Eye Res., 16, 323-351; Hyatt & Dowling, 1997, Invest. Ophthalmol. Vis. Sci., 38, 1471-1475) and its synthesis in the course of the phototransduction cascade (McCaffery et al., 1996, Proc. Natl. Acad. Sci. USA, 93, 12570-12574), retinoic acid is a promising candidate for mediating light adaptational processes. It was therefore examined whether retinoic acid could influence those physiological properties of retinal cells that are modulated by the ambient light levels.

The experiments were performed in the fish retina which is best studied with respect to the adaptational processes. Intracellular recordings of light-induced responses were obtained from horizontal cells, and the effect of exogenously applied retinoic acid on the response properties was studied in the dark-adapted retina. Retinoic acid modulated the receptive field size, the overall responsiveness, and the spectral response characteristics of horizontal cells in a way identical to the situation when a previously dark-adapted retina was subjected to light adaptation. The effects were elicited within a few minutes introducing a new property of retinoic acid which is hitherto only known for its long-lasting effects in developmental processes.

These findings invoke retinoic acid as a novel modulator mediating light adaptation in the retina.

(2) A novel role for gap junction proteins in the retina

Gap junctions are specialized intercellular contact sites representing the morphological correlate of electrical synapses. They consist of channels being composed of two hexameric membrane-spanning halves (hemichannels) each provided by one of the adjacent cells at a time. Recent findings in the fish retina propose the existence of such hemichannels, but not of a functional gap junction, at the terminal dendrites of horizontal cells, which are part of the cone synaptic complex (Janssen-Bienhold et al., 2001, Vis. Neurosci., 18, 169-178). These hemichannels are composed of the protein connexin26 and are suggested to mediate the inhibitory feedback from horizontal cells to cone photoreceptors (Kamermans et al., 2001, Science, 292, 1178-1180), which is a crucial step at the first level of synaptic integration in the neuronal cascade of vision, but yet not fully understood. Since the feedback action was first described in the turtle retina where it is a prominent feature, a multi-method approach based on molecular, anatomical, and electrophysiological techniques was performed to look for evidences of an involvement of hemichannels in the turtle feedback action.

Connexin26 mRNA as well as protein were detected in the turtle retina. The connexin protein revealed a prominent localization in horizontal cell dendritic membranes near the photoreceptor synapse, a location evidentially being devoid of gap junctions and


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well-suited for interfering with the feedback action. To investigate the physiological implications of these findings, light-evoked responses from horizontal cells were intracellularly recorded in the intact retina, while hemichannels were chemically blocked. In these experiments, horizontal cells displayed changes of the resting membrane potential and light response characteristics that were in accordance with a suppression of the feedback.

Feedback in the fish retina is suggested to work via a nonsynaptic, so-called ephaptic, mechanism involving connexin26 hemichannels (Kamermans et al., 2001). The actual findings from the turtle retina support this mechanism which therefore might be a common feature at the first visual synapse in vertebrates.

(3) Light-evoked activity of single neurons in the intact mouse retina

In the past decades, intracellular recordings from retinal neurons have eminently contributed to the understanding of the retinal physiology of cold -blooded animals. Besides that, successful attempts have been performed to extend this method to the mammalian species. But unfortunately, this is mostly lacking for the mouse, which on the other hand is a favored experimental animal due to its easy accessibility to the transgenic techniques. Therefore, this project was aimed at closing this gap.

The superfused eyecup preparation successfully used with cold-blooded animals was adapted to the mouse. In this kind of preparation, the retina retains contact with the pigment epithelium prolonging their viability and enabling changes of the adaptational condition with respect to the ambient illumination. At present, a few minutes lasting intracellular recordings of light-evoked activity could be performed from ganglion cells and horizontal cells. Recordings from horizontal cells were used to study the impact of rod photoreceptor absence on light adaptational properties.

The findings obtained by recording and tracer injection lead to the conclusion that light responsiveness and gap junctional communication of mouse horizontal cells are regulated by ambient light conditions in a manner similar to cold-blooded vertebrates. Surprisingly, this impact of ambient illumination persisted even in the absence of the vast majority of photoreceptors.

Description of college-specific tasks: Participation in seminars of the graduate school and the SFB „Neurocognition“,Organized contacts and transfer between visual and auditory domain

Workshops: July 17–18, 2001: »Das Wissen der Forschung – verständlich für Laien« organized

by the Deutsche Forschungsgemeinschaft; Kiel, Germany Nov 29, 2001: Junior Scientists Workshop, Oldenburg; oral presentation given

concerning the representation of the graduate school Mar 10–16, 2002: Tutorial in the EMBO practical course »Electrical coupling in the

retina«, Oldenburg

Attended conferences: Apr 29–May 04, 2001: Meeting of the Association for Research in Vision and

Ophthalmology (ARVO); Fort Lauderdale, USA June 07–10, 2001: 28th Göttingen Neurobiology Conference / 4th Meeting of the

German Neuroscience Society; Göttingen, Germany July 13–17, 2002: 3rd Forum of European Neurosciences by the Federation of

European Neurosciences (FENS); Paris, France


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Publications and lectures: Pottek, M. & Weiler, R. (2000). Light-adaptive effects of retinoic acid on receptive field properties of

retinal horizontal cells. Eur. J. Neurosci., 12, 437-445. Weiler, R., Pottek, M., He, S. & Vaney, D.I. (2000). Modulation of coupling between retinal horizontal

cells by retinoic acid and endogenous dopamine. Brain Res. Rev., 32, 121-129. Weiler, R., Pottek, M., Schultz, K. & Janssen-Bienhold, U. (2001). Retinoic acid, a neuromodulator in

the retina. Prog. Brain Res., 131, 309–318. Pottek, M., Hoppenstedt, W., Janssen-Bienhold, U., Schultz, K., Perlman, I. & Weiler, R. (2003).

Contribution of connexin26 to electrical feedback inhibition in the turtle retina. J. Comp. Neurol., 466, 468–477.

Conference presentations: Pottek, M., Schultz, K., Janssen-Bienhold, U. & Weiler, R. (2001). Physiological and anatomical

evidence for an involvement of connexin26 in the negative feedback loop between horizontal cells and cones in the turtle retina. Invest. Ophthalmol. Vis. Sci., 42, S671.

Pottek, M., Schultz, K., Janssen-Bienhold, U. & Weiler, R. (2001). Involvement of connexin26 hemichannels in the feedback pathway of the outer retina in fish and turtle. In: The Neurosciences at the Turn of the Century. Proceedings of the 4th Meeting of the German Neuroscience Society 2001, Volume I (Elsner, N & Kreutzberg, G.W., eds.) p. 80, Georg Thieme Verlag, Stuttgart, New York.

Pottek, M., Hoppenstedt, W., Schultz, K., Janssen-Bienhold, U. & Weiler, R. (2002). Connexin26 hemichannels in the feedback loop of the turtle outer retina. FENS Abstracts Volume I, A017.24.

Weiler, R., Pottek, M., Seeliger, M. & Humphries, P. (2003). Dynamics of horizontal cell coupling in wild type and rhodopsin knockout mouse retina. Invest. Ophthalmol. Vis. Sci., 44, eAbstract 4174.

Pottek, M. & Weiler, R. (2003). Light-dependent properties of retinal horizontal cells in wild type and rhodopsin knockout mice. In: The Neurosciences from Basic Research to Therapy. Proceedings of the 5th Meeting of the German Neuroscience Society 2003 (Elsner, N & Zimmermann, H., eds.) p. 589, Georg Thieme Verlag, Stuttgart, New York.


Occupation after leaving the graduate school: Research associate at Max Planck Institute for Polymer Research, Mainz, Germany


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Dr. Huan Zhou, Carl von Ossietzky Universität Oldenburg

Progressive Compression of Audio Signals

Scalable 1-D signal compression issue has been explored. A fine-grain scalable audio compression scheme has been developed, based on proposed novel combined significance tree mapping technique. Such a scheme shows much higher compression efficiency than existing algorithms in the same style, and achieves competitive performance compared to the state-of-the-art MPEG AAC and BSAC schemes.

Description of college-specific tasks: Assist Prof. Jesko Verhey on Matlab simulation, Contact person for asian students.

Publications and lectures: H. Zhou, A. Mertins, S. Strahl (2005) “An Efficient, Fine-Grain Scalable Audio Compression Scheme”,

AES. Preprint 6435

Publications in preparation: H. Zhou, A. Mertins, “A New Tree-based Scalable Compression Scheme with Application on Audio

Coding”, submitted to IEEE. Trans. On Speech and Audio Processing (under the 2nd revision).


Occupation after leaving the graduate school (if applicable): R&D Engineer, Panasonic Singapore Lab. Pte Ltd


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REPORT OF QUALIFICATION STIPENDIATE

Prashanth D’Souza, M.Eng., Universität Oldenburg

Cortical Mechanisms of oculomotor control

Group Leader: Prof. Dr.Mark W. Greenlee

In connection to the on-going projects at the lab, an analysis program for eye-tracking protocols was developed. The program was written in Delphi, and was maily suitable for off-line analysis of eye-movement protocols, although the algorithms developed are suitable for online analysis as well. Contributions were made to other projects at the lab as well, particularly, in simulations of oculomotor models in MATLAB and visual stimulus generation.

Auditory fMRI

Group Leader: Dr. Stefan Uppenkamp

Setting up and running the MR scanner and a compatible head phone system, and in finding solutions to technical problems related to stimulus generation/timing and data acquisition.

Thesis period: Qualifizierungsstipendium June 2003 – May 2004 (1year)

Publications and lectures: Özyurt, J., DeSouza, P., West, P., Weerda, R., Rutschmann, R. M., Greenlee, M. W. (2002). Kortikale

Aktivität und okulomotorisches Verhalten bei visuell geleiteten und gedächtnisgeleiteten Sakkaden. 44. Tagung experimentell arbeitender Psychologen. In: Experimentelle Psychologie. Baumann, M., Keinath, A., Krems, J. F. (Eds., 2002). Regensburg: Roderer, p. 175.

Greenlee, M. W., Özyurt, J., DeSouza, P., West, P., Weerda, R., Rutschmann, R. M. (2001). Comparison of cortical activity and oculomotor performance in gap, step and memory-guided tasks. Society for Neuroscience Abstracts. http://sfn.scholarone.com/itin2001/


Occupation after leaving the graduate school (if applicable): PhD. Student at the Institute of Neuroinformatics, ETH Zurich.


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Short reports of the contributing research groups

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International Graduate School for Neurosensory Science, Systems and Applications

Appendix II: Short reports of the contributing research groups Reporting period 7/2002 – 6/2005

Short report H. Colonius .........................................................................................................3 Short report H. Duifhuis ..........................................................................................................5 Short report U. Feudel.............................................................................................................7 Short report M. W. Greenlee ..................................................................................................9 Short report A. Hein...............................................................................................................11 Short report B. Kollmeier ......................................................................................................13 Short report J. Kretzberg ......................................................................................................17 Short report V. Mellert...........................................................................................................20 Short report A. Mertins ..........................................................................................................25 Short report J. B. T. M. Roerdink .........................................................................................28 Short report D. G. Stavenga.................................................................................................31 Short report J. L. Verhey.......................................................................................................36 Short report R. Weiler ...........................................................................................................39


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3

Short report H. Colonius

Research contributions to the topics of the InterGK

Multisensory object perception

The integration of stimulus information from different modalities to build a coherent representation of the outside world is a central problem for any organism. At an early level of processing, it critically depends on the spatiotemporal contiguity of the stimulus information received by the separate sensory channels. In Colonius & Diederich (2004a), we have presented a time-window-of-integration (TWIN) model that accounts for multisensory integration effects observed in the measurement of saccadic eye movements within a general theoretical framework (see also Diederich & Colonius, 2004a). Diederich & Colonius (2004b) and Arndt & Colonius (2003) have studied the specific effects of stimulus intensity and temporal stimulus configuration in bimodal and trimodal (visual-auditory-tactile) situations. In particular, we found behavioural evidence for a trimodal enhancement effect beyond the well-known bimodal interaction effects. In Diederich & Colonius (u. rev.), we developed specific versions of the TWIN model to account for the spatial effects of stimulus laterality and eccentricity (see also Diederich et al., 2003). A Bayesian model for the effects of stimulus intensity and signal-to-noise ratio on the detection of multisensory stimuli at the neural level was proposed in Colonius & Diederich (2004b) and in Colonius & Diederich (2002). Kirchner & Colonius (2004, in press-a, in press-b) investigated the specific role of interstimulus contingencies on saccadic eye movements. In Akerfelt et al. (in press) and in Özyurt et al. (2003) we studied the effect of tactile and auditory stop signals, respectively, in a saccadic countermanding task and we found evidence against a common model for saccadic inhibition.

Interactions with the remainder of the InterGK

Interactions in the form mutual discussions and consultations have taken place with several groups of the InterGK. In particular, with the psychoacoustics group (Kollmeier, Mellert) on spatial localization in visual-auditory eye movement control; with the psychology/ neuropsychology groups (Bekkering, Greenlee) on oculomotor function; and with the theoretical physics/biophysics groups (Feudel, Dau) on psychophysical modeling. More recently, interaction in terms of developing common methods of data analysis has begun with the group of G Klump (auditory psychophysics/neuroethology).

Publications within the topics of the InterGK (7/2002-7/2005)

Peer reviewed journal articles and book chapters

Akerfelt, A., Colonius, H., & Diederich, A. (in press-a). Visual-tactile saccadic inhibition. Experimental Brain Research

Kirchner, H., & Colonius, H. (in press-b). Cognitive control can modulate intersensory facilitation: Speeding up visual antisaccades with an auditory distractor. Experimental Brain Research (Special issue on multisensory processing)

Kirchner, H., & Colonius, H. (in press). Interstimulus contingency facilitates saccadic responses in a bimodal go/no-go task. Cognitive Brain Research


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Colonius H, Diederich A (2004a) Multisensory interaction in saccadic reaction time: A time-window-of-integration model. Journal of Cognitive Neuroscience 16 (6): 1000-1009

Colonius H, Diederich A (2004b) Why aren't all deep superior colliculus neurons multisensory? A Bayes' Ratio Analysis. Cognitive, Affective, and Behavioral Neuroscience 4(3), 344-353

Diederich A, Colonius H (2004a) Modeling the time course of multisensory interaction in manual and saccadic responses. In: Calvert G, Spence C, Stein BE (eds) Handbook of multisensory processes, MIT Press, Cambridge, MA, pp.395-408.

Diederich, A. & Colonius, H. (2004b). Bimodal and trimodal multisensory enhancement of reaction time: Effects of stimulus onset and intensity. Perception & Psychophysics, 66 (8), 1388-1404

Kirchner, H., & Colonius, H. (2004). Predictiveness of a visual distractor modulates saccadic responses to auditory targets. Experimental Brain Research, 155, 257-260.

Arndt, P.A. & Colonius, H. (2003). Two stages in crossmodal saccadic integration: Evidence from a visual-auditory focused attention task. Experimental Brain Research, 150, 417-426.

Özyurt, J., Colonius, H., & Arndt, P.A.(2003) . Countermanding saccades: Evidence against independent processing of go and stop signal. Perception & Psychophysics, 65, 420-428.

Diederich, A., Colonius, H., Bockhorst, D., & Tabeling, S. (2003). Visual-tactile interaction in saccade generation. Experimental Brain Research, 148, 328-337.

Colonius, H., & Diederich, A. (2002). A maximum-likelihood approach to modeling multisensory enhancement. In: T.G. Dietterich, S. Becker, & Z. Ghahramani, Advances in Neural Information Processing Systems 14, Cambridge: MIT Press.

Submitted journal articles

Diederich, A. & Colonius, H. (u.rev.). Modeling spatial effects in visual-tactile saccadic reaction time. Perception & Psychophysics.

Colonius H, Diederich A (submitted). The race model inequality: Interpreting a geometric measure of the amount of violation. Psychological Review.


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Short report H. Duifhuis


Cochlear modelling (see Duifhuis, 2004, Duifhuis et al., 2003, Duifhuis, 2002)

Psychophysics and physiology of pitch perception

• Dissertation project R. Renken (see Renken et al., 2005,) on auditory fMRI analysis: -motion-REST-auditory perception and brain response

• Dissertation project S. Tomaskovic on psychophysical and fMRI pitch experiments and audio-visual experiments (McGurk, lip reading), to be finished end of 2005

Speech and auditory object processing

• Based on the thesis on speech recognition employing a biophysical cochlear model by Tjeerd Andringa (22 Feb 02), a spin-off company “Soundident” was founded (together with former Ph.D. students Peter v.Hengel and Tjeerd Andringa) that is currently working on sound incidence detection.

• Dissertation project Lavinia M. Slabu, Analysis of the role of multimodal components in speech perception using psychophysical and fMRI techniques, to be finished end of 2007

Research methods for acoustic experiments with fMRI

• Dissertation project G. Hoiting on Measuring MRI noise,' finished 2005

• Dissertation project Carlos Rizzo on Minimizing acoustic artefacts in fMRI applications in cognitive neuroscience, to be finished 4/2007

Crosslinks and collaborations within the InterGK

Group Kollmeier/Mauermann/Uppenkamp (Cochlear modelling, Speech processing, auditory fMRI methods) Group Klump and Group v.Dijk (Psychophysics) Group Stavenga/van Netten/van Hateren (Receptor biophysics) Group Roerdink (Imaging)


Published journal articles and book contributions

Muresan, L., Renken, R., Roerdink, and J. B. T. M., and Duifhuis, H. (2005). ‘Automated Correction of Spin-History Related Motion Artefacts in fMRI: Simulated and Phantom Data,’ IEEE Transactions on Biomedical Engineering 52(8), 1450–1460.

Renken, R., Wiersinga-Post, J. E. C., Tomaskovic, S., and Duifhuis, H. (2004). ‘Dominance of missing fundamental versus spectrally cued pitch: Individual differences for complex tones with unresolved harmonics,’ J. Acoust. Soc. Am. 115 (5), 2257–2263.


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Duifhuis, H. (2004).‘Comment on “An approximate transfer function for the dual-resonance nonlinear filter model of auditory frequency selectivity” [J. Acoust. Soc. Am. 114, 2112–2117],’ J. Acoust. Soc. Am. 115(5), 1889–1890.

H. Duifhuis, J. M. Kruseman, and P. W. J. van Hengel (2003)‘An Improved Cochlea Model with a General User Interface,’ In: ‘The Biophysics of the Cochlea; from Molecules to Models’, edited by A.W. Gummer a.o. (World Scientific, Singapore), pp. 376-382.

H. Duifhuis (2003) Comment on: 'Active Amplification by Critical Oscillations, by F. Julicher, S. Camalet, J. Prost and T.A.J. Duke' In: 'The Biophysics of the Cochlea; from Molecules to Models', edited by A.W. Gummer a.o. (World Scientific, Singapore), pp. 24-25.

H. Duifhuis (2003) Comment on: ‘Cochlear Mechnical Distortion Products for Complex Stimuli in Response to Sound Stimulation, by A.J. Aranyosi and D.M. Freeman.’ In: ‘The Biophysics of the Cochlea; from Molecules to Models,’ edited by A.W. Gummer a.o. (World Scientific, Singapore), p. 88.

H. Duifhuis (2003) Comment on: ‘Measured and Modeled Motion of Free-Standing Hair Bundles in the Chinchilla Basal Region, by W.S. Rhode and A. Recio.’ In: ‘The Biophysics of the Cochlea; from Molecules to Models,’ edited by A.W. Gummer a.o. (World Scientific, Singapore), p. 227.

H. Duifhuis (2003) Comment on E. de Boer's comment on: ‘Response to Amplitude Modulated Waves in the Apical Turn of the Cochlea, by S.M. Khanna.’ In: ‘The Biophysics of the Cochlea; from Molecules to Models,’ edited by A.W. Gummer a.o. (World Scientific, Singapore), p. 259.

H. Duifhuis (2003) Comments in: Discussion Session. In: ‘The Biophysics of the Cochlea; from Molecules to Models’, edited by A.W. Gummer a.o. (World Scientific, Singapore), pp. 567, 577, 584, 591.

L. Muresan, R. Renken, J.B.T.M. Roerdink and H. Duifhuis (2002).‘Position-history and spin-history artifacts in fMRI time-series.’ In: ‘Proc. Medical Imaging 2002: Physiology and Function from Multidimensional Images’, A. V. Clough and C.-T. Chen (eds.), Proc. SPIE vol. 4683, 2002, pp. 444-451.

Supervised dissertations within the InterGK

R.J. Rencken (3 Sep 2004) 'Topics in auditory fMRI analysis: -motion-REST-auditory perception and brain response-' RUG

G.J. Hoiting (27 May 2005) 'Measuring MRI noise'


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Short report U. Feudel


Object perception in the auditory system

The aim of our project was to model neuronal responses to acoustic stimuli. To this end we started with a time series analysis of neuronal recordings from experiments with starlings concerning the comodulation detection difference (CDD). These experiments performed by the group of G Klump in Oldenburg use signals masked by comodulated noise which means that a narrowband sound signal is presented together with noise in different frequency bands, and the signal as well as the noise are modulated by coherent or incoherent amplitude fluctuations. It has been shown that the presence of comodulated noise can improve the detection of sounds compared to the case where uncorrelated noise is used to mask the signal (e.g. Verhey et al., 2003). We found that already the analysis of the time and population averaged firing rates of the neurons encoding the compressed envelope of the filtered stimulus yields an explanation of the CDD effect. Our model proposes a within-channel mechanism for the detection of the signal. Despite the simplicity of our model, which does not use any higher level neuronal processing, the results are in good agreement with the experiments (Buschermöhle et al., 2005). This interesting result has been achieved mainly by M Buschermöhle who joined the InterGK only one year ago and JA Freund who works as a senior scientist in my group.

Our model is currently further analysed by taking into account varying recording sites in order to determine the exact extent to which the CDD effect can be explained by our simple model. Currently we prepare a further paper comparing human psychophysical data taken from the literature with our model predictions. These studies are not completed yet.

According to our original aim of finding a relationship between the temporal neural coding and the acoustic input signal we also tried to analyse the neuronal response itself using spike sorting algorithms. This has been initially done by the PhD student K Krajsek, who joined the InterGK only for a few months and left due to an employment as a PhD student with a full BAT IIa payment in the Informatics department at Frankfurt University. It turned out that the available spike sorting algorithms do not perform sufficiently reliable because the signal-to-noise ratio of the currently used extracellular multi-unit recordings is far too low. Resulting spike sequences were thus not trustworthy enough to analyse them for spike patterns. We have postponed the originally planned investigations until recordings with a higher signal-to-noise ratio (or more efficient sorting algorithms) will be available.

Crosslinks and collaborations within the InterGK

The work of our group is strongly related with the work of other groups in the InterGK, in particular with the group of G Klump. We use the experimental data collected by this group (M Bee, U Langemann) and discuss regularly physiological and experimental issues to link our results to the experimental findings as closely as possible. This close collaboration leads to joint publications of our results. We have also benefited a lot from discussions with J Verhey who studied effects similar to CDD in psychophysical experiments. The latter connection will be even strengthened


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in future since we have planned joint experiments with the group of J Verhey concerning the investigation of stochastic resonance with comodulated noise.


Published journal articles

Tetzlaff T, Buschermöhle M, Geisel T, Diesmann M “The spread of rate and correlation in stationary cortical networks”, Neurocomputing 52-54 (2003), 949-954


Buschermöhle M, Feudel U, Bee MA, Klump GM, Freund JA “Signal detection enhanced by comodulated noise“ submitted to Phys. Rev. Lett.

Liepelt S, Freund JA, Schimansky-Geier L, Neiman A, Russel DF: “Information Processing in Noisy Burster Models of Sensory Neurons”, accepted for publication in J.Theor.Biol.


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Short report M. W. Greenlee


Functional magnetic resonance imaging in the Human visual and oculomotor system

The group is interested in the interplay between the human visual and oculomotor systems. The experimental paradigms range from simple saccade and pursuit tasks to more complex visual search and attention tasks. Healthy subjects perform these tasks in the MR scanner while T2*-weighted images of the entire brain are collected every 2 seconds. We have developed a technique to monitor eye movements with high spatial and temporal resolution inside of the magnet. In event-related designs, we can trace brain activity related to correctly performed eye movements and compare these to trials on which the subjects make errors. We also apply signal-detection theory to identify processes related to criterion setting and sensory-based decision making.

In Vallines et al. (under review), we dissociated the processes of attention shifting, saccade programming and execution and found contralateral activity in area V3 correlated with saccade programming. The process of saccadic suppression was examined in another study of Vallines et al. (submitted). The results suggest that saccadic suppression emerges from subcortical processes before stimulus-related activity reaches primary visual cortex. The shorter the SOA between stimulus presentation and beginning of saccade execution is, the weaker is the retinotopic BOLD response in primary visual cortex evoked by the stimulus.

In Weerda et al. (under review), we studied the influence of nonspatial visual selective and divided attention on the activity in extrastriate visual cortex. We found a mild effect of the attended stimulus feature on neuronal activity in cortical areas known to be specialised in the processing of the respective feature. The extent to which primary visual cortex contributes directly to the emergence of conscious visual percepts is examined in another study by Weerda et al. The present results suggest that the activity of primary visual cortex is much more correlated with perception than with the actual stimulus intensity, which supports the notion of a direct contribution of primary visual cortex to visual awareness.


Interactions in the form mutual discussions and consultations have taken place with several groups of the InterGK. In particular, with the psychoacoustics group (Kollmeier) on functional brain imaging of auditory processing and with the neuroimaging/ psychology groups (Cornelissen, Colonius) on oculomotor function.


Knauff, M. Mulack, T., Kassubek, J., Salih, H.R., Greenlee, M.W. Spatial imaging in deductive reasoning: a functional MRI study. Cogn. Brain Res. 13, 203-212 (2002).

Büchert, M. Greenlee, M.W., Rutschmann, R.M., Kraemer, F.M. Luo, F. Hennig, J. fMRI Evidence for binocular interactions in Human visual cortex, Exp Brain Res 145(3): 334-9 (2002)


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Cornelissen FW, Kimmig H, Schira M, Rutschmann RM, Maguire RP, Broerse A, Den Boer JA, Greenlee MW. Event-related fMRI responses in the human frontal eye fields in a randomized pro- and antisaccade task.Exp Brain Res. 145(2):270-4 (2002).

Reinvang, I., Magnussen, S., Greenlee, M.W. Hemispheric asymmetry in visual discrimination and memory: ERP evidence for the spatial frequency hypothesis. Exp Brain Res. 144(4):483-95 (2002).

Greenlee, M.W., Schira, M.M., Kimmig, H. Coherent motion pops out during smooth pursuit. NeuroReport 19;13(10):1313-6 (2002).

Magnussen, S. Greenlee, M.W. Aslaksen, P.M., Kildebo, O.O. High-fidelity perceptual long-term memory revisited – and confirmed. Psych. Science, 14, 74-76 (2003).

Müller, R., Bochmann, G. Greenlee, M.W., Göpfert, E. (2003) Relationship between motion VEP and perceived velocity of gratings: effects of stimulus speed and adaptation Doc Ophthalmol. 107(2):115-26.

Rutschmann, R.M., Greenlee, M.W. (2004) BOLD response in dorsal areas varies with relative disparity level. NeuroReport, 22, 615-619.

Müller, R., Göpfert, E., Leineweber, M., Greenlee, M.W (2004) Effect of adaptation direction on the motion VEP and perceived speed of drifting gratings. Vision Res, 44, 2381-92.

Pasternak, T., Greenlee, M.W., (2005) Working memory in primate sensory systems Nature Neurosc Rev, 6, 97-107.

Book chapters

Greenlee, M.W. Sehen, Visuelle Aufmerksamkeit. In: Birbaumer, N., Elbert, T. (Hrsg.) Enzylopädie der Psychologie, Band: Biologische Psychologie. Biologische Grundlagen der Psychologie. pp. 125 – 247. Hogrefe: Göttingen (2002).

Greenlee, M.W. Functional magnetic resonance imaging and positron emission tomography studies of motion perception, eye movements and reading. In: Fahle, M., Greenlee, M.W. Neuropsychology of Vision. Oxford University Press (2004).

Weerda, R., Vallines, I., Thomas, J. P. & Greenlee, M. W. (2003). Individual Differences in Cognitive Strategies and Attentional Effects During Stimulus Uncertainty: Evidence from Psychophysics and fMRI. In: Reinvang, I., Greenlee, M. W. & Herrmann, M. (Eds.) The Cognitive Neuroscience of Individual Differences - New Perspectives. Hanse Advanced Studies, Vol IV.

Under review

Vallines, I., Rutschmann, R.M., Özyurt, J., Bodis-Wollner, I.G., Greenlee, M.W. Visual cortex activation during intentional saccadic eye movements and shifts in spatial attention. (under review).

Knauff, M. Fangmeier, T. Raabe, M. Greenlee, M.W. the neural correlates of social cooperation in Humans (under review).

Weerda, R., Vallines, I., Thomas, J.P., Rutschmann, R.M., Greenlee, M.W. Effects of Nonspatial Selective and Divided Visual Attention on fMRI BOLD Responses. Exp Brain Res. (under review).

Vallines, I., Greenlee, M.W. Saccadic suppression of retinotopically localized stimuli in Human primary visual area V1 (under review).

Özyurt, J., Rutschmann, R.M., Greenlee, M.W. Cortical Activation during Visually guided and Memory guided Saccadic Eye Movements as measured by fMRI (under review)


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Short report A. Hein


Functional and diagnostic imaging

The improvement of imaging techniques is one main topic of my research. Up to now, the research was focused on the intraoperative integration of image modalities as CT (Albrecht et al., 2000), x-ray projective imaging and 3d reconstruction (Szymanski et al., 2003; Hein and Kirschstein, 2004), ultrasonsic imaging (Lüth et al., 2005) and surface scanning (Rose et al., 2004). The combination of imaging systems with exact position measurement (navigated imaging) and correction algorithms was used to acquire relevant images during a surgical intervention.

First preliminary experiments have been carried out to determine the spatial deformation of MR images taken with a BOLD sequence. Using a geometrically known phantom it have been shown that local deviations between distances from the CAD model and distances measured in the image are within a range of a view millimetre. Because of that, the detection of the brain activity and the reconstruction of the brain geometry are erroneous. Statistical methods that not only interpret the time series of measurements as a signal measured at a fixed position and calibration algorithms are under development. In addition, a position measurement system (Polaris, NDI, Canada) has been integrated into the MRI to determine the spatial position of the head of the patient/test person. In this way the spontaneous movement of the head can be detected independently and can be used for motion correction.

Applications

Another main topic of my research is the integration of partially automated assistant systems into operating rooms. The development of their human-machine interfaces is focused on haptic feedback for the interactive control of robotic systems (Hein and Lüth, 2000, 2001a and 2001b) and the intuitive visual feedback by navigated viewing (Weber et al., 2003a and 2003b). An additional information channel through vibration is planned to investigate within one proposed research / dissertation topic.

As a basis for the optimal detection of the neuronal processing of acoustic stimulus by functional MR imaging a system for active noise cancellation has been projected and first preliminary measurement s of the position dependent noise within the MR scanner have been carried out.


Because of the short time since I am member of the InterGK the interactions are limited to the identification of potential co-operation topics. Interactions already exist with the group of Birger Kollmeier and Volker Mellert in the field of active noise cancellation in the MRI and the processing of fMRI data (mentioned above). Additional links have been identi fied to the group of Jutta Kretzberg and Volker Mellert in the field of technical applications of tactile / vibratory information processing.


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Peer reviewed journal articles and patents

Hein, A., T. Lüth (2001a): Architektur und Anwendungen eines zugelassenen Medizinroboters. at (Automatisierungstechnik), Schwerpunktheft "Teleautomation", Vol. 49, 7:2001, pp. 320-328

Lueth, T.; Hein, A.; Jank, E.; Klein, M.; Hoppe, F. (2005): Device and method for the reproducible positioning of an object relative to an intracorporeal area. PCT WO-Patent WO 2005/032376, Date of publication: 14.04.2005

Proceedings

Hein, A.; U. Kirschstein (2004): Navigated Imaging for Angiography - Concept and Calibration. IEEE Int. Conf. on Mechatronics and Robotics, Aachen, Germany, Sept. 13-15, pp. 1409-1414

Rose, A.; Hein, A.; Lüth, T. (2004): An optically based tactile system for interacti ve gradual surface scanning. CARS 2004, Chicago, USA, June 23-26, pp. 573-578

Weber, S.; Klein, M.; Hein, A.; Krueger, T.; Lüth, T.; Bier, J. (2003a): Application of Different Visualization Concepts in the Navigated Image Viewer. IROS – Int. Conf. on Intelligent Robots and Systems, Las Vegas, USA, 27.-31.11.2003, pp. 779-784

Weber, S.; Klein, M.; Hein, A.; Krueger, T.; Lüth, T.; Bier, J. (2003b): The Navigated Image Viewer – Evaluation in Maxillofacial Surgery. MICCAI – Int. Conf. on Medical Image Computing and Computer-Assisted Interventions, Montreal, Canada, 4.-7.11.2003, pp. 762-769

Szymanski, D.; Hein, A.; Lüth, T. (2003): NAVI-X A Planning and Treatment System for Dental Implantology Based on Navigated Projection Images. CARS 2003, London, England, June 25.-28. 2003, pp. 1243-1249

Hein, A., T.C. Lueth (2001b): Control Algorithms for Interactive Shaping. ICRA IEEE Int. Conf. on Robotics and Automation, Seoul, Korea, May, 2001, pp. 2025-2030

Hein, A., T. Lüth (2000): Architektur einer interaktiv bedienbaren Robotersteuerung für chirurgische Anwendungen. Robotik 2000, Berlin, Germany, 29.-30. June. In VDI-Berichte; 1552, VDI Verlag, pp. 403-408

Albrecht, J., A. Hein , T. Lueth (2000): Measurement of the Slice Distance Accuracy of the Mobile CT Tomoscan. CARS 2000, Computer Assisted Radiology and Surgery, San Francisco, USA, June 28 - July 1, pp. 651-655


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Short report B. Kollmeier


Adaptation in the auditory system

A characterization of the auditory neurosensory transformation was performed with brainstem-evoked responses using chirp stimuli and frequency-following responses (dissertation Fobel, 2003), distortion-product otoacoustic emissions (Mauermann & Kollmeier, 2004) and the low-level stapedius reflex (Müller-Wehlau et al., 2005). The results reflect the role of compressive, active mechanisms in the cochlea whereas the response at the brainstem level and primary auditory cortex appears to be surprisingly linear and time-invariant.

Time-dependent properties of Loudness perception and appropriate loudness models were studied by considering the relation between different subjective loudness scales (Blum et al., 2002), the dependence of loudness summation on the duration of a stimulus (Verhey & Kollmeier, 2002) and by developing and comparing appropriate time-dependent loudness models for normal and hearing-impaired listeners (dissertation Appell, 2002).

Finally, the relation between perceived loudness and objective quantities was studied using subjective loudness estimates, the fine structure of the absolute hearing threshold, and the spectral fine structure of (objective) otoacoustic emissions (Mauermann et al., 2004, dissertation Mauermann, 2004).

Object perception in audition

In order to better understand the role of Modulation processing & perception as a prerequisite for auditory object perception, the “effective” modulation frequency resolution was determined (dissertation Ewert, 2002) and a neural model for modulation processing was developed that is based on the interaction between very few neural units (dissertation Dicke, 2003).

Binaural interaction as another prerequisite for object perception and segregation was studied by considering acoustically evoked electrical recordings from the scalp (EEG) that result for lateralization and localization tasks including “time-intensity trading” conditions (Riedel & Kollmeier, 2002a,b,c, Riedel & Kollmeier 2003, Kollmeier & Riedel, 2005, dissertation Riedel, 2002), tasks using individual HRTFs to study the processing of natural localization cues (dissertation Junius, 2005) and the human electrophysiology of the precedence effect using a mismatch negativity paradign (Damaschke et al., 2005, dissertation Damaschke, 2004). The results indicate that a rough lateralization/localization image (with a direct trading of interaural time- and intensity differences and no correlate of the precedence effect) is accessible at the brainstem level, whereas a more refined auditory image (with a separate time- and intensity “image” and an objective correlate of the precedence effect) is built up at the cortical level.

More complex properties of object perception were studied with Speech perception/speech intelligibility studies. The design and validation of efficient methods for determining the speech intelligibility in noise was described by Brand & Kollmeier, (2002) and the “Oldenburg Sentence test” was shown to be a valid tool for clinical audiology (Wagener & Kollmeier, 2004, dissertation Wagener, 2003).,


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Applications

The application of auditory models to audio and speech quality prediction was demonstrated by an approach to estimate signal-to-noise ratio based on the modulation spectrogram (i.e., two-dimensional representation of center frequency vs. modulation frequency, Tchorz & Kollmeier, 2002). Likewise, several auditory-model based methods for predicting the performance of noise reduction in hearing aids were developed and compared (Marzinzik & Kollmeier, 2003). Finally, an objective prediction of audio quality degradation by nonlinear processing (such as, e.g., audio codecs) was developed and tested in the dissertation R. Huber (2003).

A related application of auditory model is robust speech recognition (Kollmeier, 2003) which could considerably be improved by using second-order auditory cues (e.g., Gabor-patterns in the time-frequency domain) motivated by physiological and psychoacoustical findings (dissertation Kleinschmidt, 2002).

As a practical application, signal processing & Noise reduction for hearing aids was considered (Kollmeier, 2002) using various techniques: Marzinzik & Kollmeier (2002) employed a monaural spectral subtractions scheme, Tchorz & Kollmeier (2003) used the estimated SNR from the modulation spectrogram (see above) to steer a Wiener filter. A binaural/two channel approach was employed by Anemüller & Kollmeier (2003) who developed a blind sound source separation algorithm, and by the dissertation Nix (2005) who employed a computationally expensive sequential Monte Carlo method.


Psychoacoustics: Research groups J. Verhey, V.Mellert, H. Colonius, G.Klump

Auditory neurophysiology: Research groups G.Klump, H. Duifhuis, D. Stavenga

Signal processing: Research groups A. Mertins, A. Hein

Modelling: Research groups H. Duifhuis, U. Feudel, H.Colonius, G. Klump



Blum R, Hohmann V, Appell JE, Kollmeier B (2002) Modellierung der Kategoriallautheit. Z Audiol 41: 76-89

Brand T, Kollmeier B (2002) Efficient adaptive procedures for threshold and concurrent slope estimates for psychophysics and speech intelligibility tests. Journal of the Acoustical Society of America 111: 2801-2810

Kollmeier B (2002) Cocktail-Parties und Hörgeräte: Biophysik des Gehörs. Physik Journal 1: 39-45

Marzinzik M, Kollmeier B (2002) Speech pause detection for noise spectrum estimation by tracking power envelope dynamics. IEEE Transactions on Speech and Audio Processing 10: 109-118

Riedel H, Kollmeier B (2002a) Auditory brain stem responses evoked by lateralized clicks: Is lateralization extracted in the human brainstem? Hearing Research 163: 12-26


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Riedel H, Kollmeier B (2002b) Comparison of binaural auditory brain stem responses and the binaural difference potential evoked by chirps and clicks. Hearing Research 169: 85-96

Riedel H, Kollmeier B (2002c) Auditory brain stem responses evoked by lateralized clicks: Is lateralization extracted in the human brainstem? Hearing Research 163: 12-26

Tchorz J, Kollmeier B (2002) Estimation of signal-to-noise ratio with amplitude modulation spectrograms. Speech communication 38: 1 - 17

Verhey J, Kollmeier B (2002) Spectral loudness summation as a function of duration. Journal of the Acoustical Society of America 111 : 1349-1358

Anemüller J, Kollmeier B (2003) Adaptive separation of acoustic sources for anechoic conditions: A constrained frequency domain approach. Speech Communication 39: 79-95

Marzinzik M, Kollmeier B (2003) Predicting the subjective quality of noise reduction algorithms for hearing aids. Acta acustica/Acustica 89: 521-529

Riedel H, Kollmeier B (2003) Dipole source analysis of auditory brain stem responses evoked by lateralized clicks. Zeitschrift für Medizinische Physik 13: 75-83

Tchorz J, Kollmeier B (2003) SNR Estimation based on amplitude modulation analysis with applications to noise suppression. IEEE Trans. Speech & Audio Processing 11: 184-192

Kollmeier B (2003) Auditory principles in speech processing: Do computers need silicon ears?. In Proceedings of the 8th European Conference on Speech Communication and Technology (Eurospeech invited plenary talk), ICSA International Speech Communication Association:5-8.

Mauermann M, Kollmeier B (2004) Distortion product otoacoustic emission (DPOAE) input/output functions and the influence of the second DPOAE source. J. Acoust. Soc. Am. 116: 2199-2212

Mauermann M, Long GR, Kollmeier B (2004) Fine structure of hearing threshold and loudness perception. J. Acoust. Soc. Am., 116: 1066-1080

Wagener K, Kollmeier B (2004) Göttinger und Oldenburger Satztest. Zeitschrift für Audiologie/ Audiological Acoustics, 134

Kollmeier B, Riedel H (2005) What can auditory evoked potentials tell us about binaural processing in humans?. In Auditory signal processing: Physiology, psychoacoustics, and models - 13th International Symposium on Hearing, editors: Pressnitzer, Cheveigne, McAdams, Collet, Springer Verlag, New York, p. 362-369

Müller-Wehlau M, Mauermann M, Dau T, Kollmeier B (2005) The effects of neural synchronization and peripheral compression on the acoustic-reflex threshold. Acoustical Society of America, vol 117(5), pp 3016-3027,

Damaschke J, Riedel H, Kollmeier B (2005) Neural correlates of the precedence effect in auditory evoked potentials. Hearing Research, 205, p. 157-171


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Supervised dissertations 2002-2005

Appell, J.-E. (2002) Loudness Models for rehabilitative Audiology. Dissertation, Universität Oldenburg, Physics, Oldenburg.

Ewert, S. (2002) Auditory spectro-temporal processing in the envelope-frequency domain. Dissertation, University of Oldenburg, Medical Physics, Oldenburg.

Kleinschmidt, M.(2002) Robust speech recognition based on spectrotemporal processing. Dissertation, Carl von Ossietzky Universität, Physics, Oldenburg.

Riedel, H.(2002) Analysis of early auditory evoked potentials elicited by stimuli with directional information. Dissertation, University Oldenburg, Medical Physics, Oldenburg.

Dicke, U. (2003) Neural models of modulation frequency analysis in the auditory system. Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.

Fobel, O. (2003) Auditory brainstem and middle-latency responses with optimized stimuli: Experiments and models. Dissertation, University of Oldenburg, Medical Physics, Oldenburg.

Huber, R.(2003) Objective assessment of audio quality using an auditory processing model. Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.

Wagener, K.(2003) Factors Influencing Sentence Intelligibility in Noise. Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.

Damaschke, J. (2004) Towards a neurophysiological correlate of the precedence effect: from psychoacoustics to electroencephalography. Dissertation, Univ. Oldenburg, Oldenburg.

Mauermann, M.(2004) Fine Structure in Distortion Product Otoacoustic Emissions and Auditory Perception. Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.

Junius, D. (2005) Temporal and spatial aspects of hearing as revealed by auditory evoked potentials. Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.

Nix, J. (2005) Localization and Separation of Concurrent Talkers based on Principles of Auditory Scene Analysis and Multi-Dimensional Statistical Methods, Dissertation, University of Oldenburg, Physics, Oldenburg, Germany.


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Short report J. Kretzberg


Adaptation in the visual system

In recent years, one of the main topics of my research was to analyze sensory coding in the visual system of the fly. Using a phenomenological model of spike generation we could show that the time structure of a visual interneuron’s (H1) spike responses depend critically on the dynamics of the underlying membrane potential which is determined both by the stimulus dynamics and by signals that are not time locked to the stimulus (“noise”). Accurate time locking of spike responses to sensory stimuli is only possible if they reliably lead to high-frequency fluctuations of the membrane potential (Egelhaaf et al. 2002 & 2003). In order to determine the main source for the membrane potential noise that limits reliability and precision of coding, we compared the effects of external photon noise to effects of noise intrinsic to the fly visual system. This experimental study revealed that neuronal noise sources intrinsic to the visual system account for the majority of noise in fly visual interneurons (Grewe et al. 2003). Further modelling showed that an important aspect limiting the reliability of the interneuron’s responses is the number of excitatory and inhibitory synaptic inputs and correlations between them (Kretzberg et al. 2003).

After moving to Oldenburg in October 2004, I took the opportunity to start a close cooperation with the group of Prof. Reto Weiler and Apl. Prof. Josef Ammermüller to study population coding in the vertebrate retina. In June 2005, Dr. Andreas Thiel, who worked as a postdoc in Prof. Ammermüllers lab before, joined my lab. Based on multi electrode recordings from retinal ganglion cells (RGCs) of the turtle retina obtained by Martin Greschner (InterGK PhD student), he developed a detailed model of retinal information processing (Thiel et al., 2002, 2003a, 2004, 2005). This model is able to reproduce exact spike patterns of RGC responses to visual stimulation, including adaptation effects. With this model, he could show that network interactions of amacrine cells are essential for shaping RGC responses. In my lab, Dr. Thiel plans to do a combined experimental and modelling study about retinal population coding. The goal of this project is to investigate whether populations of RGCs could use latency differences to encode the spatial structure of visual stimuli.

Adaptation in the mechanosensory system

To study fundamental effects of neural coding of mechanosensory stimuli, I chose the nervous system of the leech as a model system. When the skin of a leech is touched lightly, the animal performs a well defined behavior the so called “local bend”. This behavior is controlled by a small neuronal network consisting of ~ 40 mostly identified neurons organized in three layers (mechanosensors, interneurons and motorneurons) that is localized in each of the leech body segments. When I worked in the lab of Prof. William Kristan at UCSD, I investigated electrophysiologicaly the properties of synaptic contacts between the interneuron and the motorneuron layer. My main findings were that the synaptic connection between interneuron and motorneuron layer does – in contrast to synapses between cells in the motorneuron layer of the local bend circuit – require presynaptic action potentials for transmitter release and show strong activity dependent effects (Kretzberg et al. 2004 & 2005).


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For my new lab in Oldenburg, I bought and established two electrophysiological setups for intracellular double recordings, one of them also equipped with tactile stimulation and video supervision of muscle movements. I have also developed custom-made software for stimulation, data acquisition and analysis. Experimental projects to investigate coding properties of the leech mechanosensory system are sufficiently prepared now, I am currently looking for students to join my lab.


As mentioned before, I am cooperating very closely with the groups of Prof. Reto Weiler and Apl. Prof. Josef Ammermüller. The links between our groups are so strong that we share equipment, teach together in several lectures and lab courses and that my group joins their lab meeting. Our common research interest is the dynamics of retinal information processing. With Prof. Weiler focussing mainly cellular, synaptical and molecular aspects, Apl. Prof. Ammermüller investigating network interactions and population responses and myself having a keen interest in coding principles, our views on retinal processing complement each other very well.

Since I share my interest in sensory coding with Jun. Prof. Jesko Verhey we are exchanging our ideas about this topic regularly. These discussions have led to a co-organized InterGK symposium on the topic of sensory coding in January 2005. For the future, we plan a concrete cooperation in regard of computational models for sensory coding on a single cell level.

To foster cooperation within the InterGK regarding future investigations of the mechanosensory system Prof. Volker Mellert, Prof. Andreas Hein and I got in touch recently. Since both Prof. Hein and I are still in the process of building up new labs and became members of the InterGK only a short time ago, a close cooperation of the mechanosensory groups in Oldenburg was not started yet, but is planned for the near future.



Kretzberg J, Warzecha A-K, Sejnowski T, Egelhaaf M (2003) Variability of postsynaptic responses depends non-linearly on the number of synaptic inputs. Neurocomputing 52-54, 313-320

Egelhaaf M, Böddeker N, Kern R, Kretzberg J, Lindemann JP, Warzecha A-K (2003) Visually guided orientation in flies: Case studies in computational neuroethology. J Comp Physiol A 189, 401-409

Grewe J, Kretzberg J, Warzecha A-K, Egelhaaf M (2003) Impact of photon noise on the reliability of a motion-sensitive neuron in the fly's visual system. J Neurosci 23, 10776-10783

Thiel A, Schwegler H, and Eurich CW (2003). Complex dynamics is abolished in delayed recurrent systems with distributed feedback times. Complexity, 8:102-108.

Egelhaaf M, Kern R, Krapp H., Kretzberg J, Kurtz R, Warzecha A-K (2002) Neural encoding of behaviourally relevant visual-motion information in the fly. Trends Neurosci 25, 96-102


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Thiel A, Wilke SD, Eurich CW, Greschner M, Bongard M, Ammermüller J, and Schwegler H (2002). Temporally faithful representation of salient stimulus movement patterns in the early visual system. In V. Cantoni, M. Marinaro, and A. Petrosino, eds., Visual Attention Mechanisms, pp. 93-100. Kluwer, New York.

Proceedings

Kretzberg J, Marin-Burgin A, Kristan WB (2005) Characterization of a central synapse in the local bend circuit of the leech. In: Zimmermann H and Krieglstein K (Eds.) Proceedings of the 6th Meeting of the German Neuroscience Society / 30th Göttingen Neurobiology Conference 2005. Neuroforum 2005, 1 Suppl.: 294B

Thiel A, Greschner M, and Ammermüller J (2005). Retinal ganglion cell burst patterns are reproduced by a computational model of intraretinal processing. In H. Zimmermann and K. Krieglstein, eds., Proceedings of the 30th Göttingen Neurobiology Conference, Neuroforum 2005, 1 Supplement. Abstract 165B.

Kretzberg J, Egelhaaf M, Kristan W, Sejnowski T (2004) Transmitting more than spikes. In: Proceedings of Cosyne Meeting

Ammermüller J, Greschner M, and Thiel A (2004). Interburst intervals in temporally structured responses of retinal ganglion cells improve stimulus intensity estimation. In FENS Forum Abstracts, vol. 2. Federation of European Neuroscience Societies. Abstract A194.2.

Thiel A, Greschner M, and Ammermüller J (2004). A retina model generating ganglion cell burst sequences with realistic temporal structure and intensity dependence. In FENS Forum Abstracts, vol. 2. Federation of European Neuroscience Societies. Abstract A194.32.

Kretzberg J, Warzecha A-K, Sejnowski TJ, Egelhaaf M (2003) Do fly motion-sensitive neurons receive spike-triggered or graded synaptic input? In: Elsner N, Zimmermann H (Eds.) Proceedings 29th Göttingen Neurobiology Conference, Thieme, Stuttgart, Abstract 1052.

Grewe J, Kretzberg J, Warzecha A-K, Egelhaaf M (2003) Impact of photon-noise on the reliability of a motion sensitive neuron in the visual system of the blowfly Lucilia. In: Elsner N, Zimmermann H (Eds.) Proceedings 29th Göttingen Neurobiology Conference, Thieme, Stuttgart, Abstract 481.

Ammermüller J, Greschner M, Thiel A, Voges N, Bongard M, and Fernández E (2003). The temporal structure of signal processing in the retina. European Biophysics Journal, 32:180. Proceedings of 4th European Biophysics Congress.

Greschner M, Thiel A, and Ammermüller J (2003). Temporal structure of retinal ganglion light responses improves stimulus estimation. In N. Elsner and H. Zimmermann, eds., Proceedings of the 29th Göttingen Neurobiology Conference, pp. 594-595. Thieme, Stuttgart.

Thiel A, Greschner M, Eurich CW, and Ammermüller J (2003b). Stimulus velocity reconstructed from retinal ganglion cell activity using Bayes' method. In N. Elsner and H. Zimmermann, eds., Proceedings of the 29th Göttingen Neurobiology Conference, pp. 588-589. Thieme, Stuttgart.

Thiel A, Greschner M, and Ammermüller J (2003a). The temporal structure of retinal ganglion cell responses and its relationship to intraretinal processing. In Annual


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Meeting Abstract Viewer/Itinerary Planner. Society for Neuroscience, Washington DC. Program No. 264.21.

Kretzberg J, Sejnowski TJ, Warzecha A-K, Egelhaaf M (2002) Variability of postsynaptic responses to spike-mediated and graded synaptic input. Society for Neuroscience Abstract 848.8.

Short report V. Mellert


Vibration perception

Vibration perception is becoming a more important issue in various research areas, which cover the range from high-level whole-body vibrations in a workplace environment including health issues to low-level hand-finger vibrations as feedback for tactile displays or to improve applications in virtual reality. Although intensively investigated almost all research is closely linked either to a specific application or to basic neurology, in particular focused on tactile perception of roughness.

The studies in the InterGK relate to the perception of vibrations at two different parts of the human hand, the fingertip and the palm providing some basic psychophysical insight. In combination with knowledge from the physiology of the human somatosensory system the objective is to model and broaden the view on the perception of tactile vibration.

A extensive literature research has been done to collect current knowledge about the human somatosensory system in order to derive a layout for a human response model. In addition psychophysical measurements have been made investigating the vibration threshold, equal-level vibrations and just noticeable difference in frequency for the finger tip and the palm. Three of the four mechanoreceptors can be distinguished in these psychophysical measurements and certain properties of the data can be related to the individual neurological properties of the respective mechanoreceptor. Based on these results and the collated neuro physiological data a three-receptor human response model was programmed mimicking the neurological behaviour of the somatosensory system.

The basic psychophysical investigation of the perception of vibration with finger and palm was complimented by applied research related to travel comfort, i.e. by whole-body perception of vibration in seats, in particular for the automotive field and in the aircraft. The relation to comfort levels was derived and principal levels of equal perception with respect to frequency and just-noticeable differences in whole-body vibrations were determined. It turned out that numerous basic psychophysical parameters (e.g. sensitivity, equal-level contours, masking) are not yet reported in literature, and a comprehensive model of perception of (whole-body) vibration is not available up to-date.

Acoustic features in technical sound

Tonality, tone, ring, spectral shapes etc. in technical sound from cars bears information on certain aspects of quality of the sound source (e.g. engine, tyre), of malfunctions and of higher cognitive aspects like e.g. sportiness or luxury. Basic psychoacoustic parameters (loudness, sharpness etc.) are only partly adequate to characterise the subjective impression. Investigations were carried out with respect to


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tyre noise. Certain feature of the sound could be identified with a modified procedure for spectral contours after MUMMERT. These features correlate very well with an acoustic quality-control for tyres. Since most of the technical sounds are not stationary, procedures must be developed to compensate for dependency on time. This is easy for engine noise of cars. The order-analysis allows for modifications in the spectral content without changing the typical sound of an accelerating or decelerating car. Relations to characteristic subjective impressions of car noise were discovered.


Links to several other groups of the InterGk are established and will be extended: • The tactile perception and the perception of vibration is investigated

psychophysically in the Acoustics Group and in parallel (electro-) physiologically in the group of J. Kretzberg. It is planned to use comparable physical stimulations and experimental settings for the subjective and the animal-model measurements. Applications to improve a human-machine interaction in appropriate interfaces are constructed in cooperation with the group of A. Hein.

• Psychoacoustic application with regard to the perception of tonal components in machinery or environmental noise is developed in close cooperation with the group of J. Verhey.

• Low-frequency perception and impact of infrasound will be investigated in an animal model with support of the group of J. Kretzberg and with psychoacoustic methodology in cooperation with the medical physics group (B. Kollmeier).

Publications and conference proceedings within the topics of the InterGK (2001-2005)

Baumann, I., M. A. Bellmann, V. Mellert, and R. Weber (2001), Wahrnehmungs- und Unterschiedsschwellen von Vibrationen auf einem Kraftfahrzeugsitz, DAGA 2001, Hamburg-Harburg, Deutschland, 2001. ISBN: (3-9804568-9-7), pp. 292/ 293. DEGA e.V., Oldenburg.

Bellmann, M. A., Baumann, I., Hillebrand, P., Mellert, V., Weber, R. (2001), Methoden zur Verbesserung der objektiven Beschreibung subjektiver Qualitätsurteile der Sitz- und Lenkradvibrationen, DAGA 2001, Hamburg-Harburg, Deutschland, 2001. ISBN: (3-9804568-9-7), pp. 294/ 295. DEGA e.V., Oldenburg, http://www.physik.uni-oldenburg.de/Docs/aku/staff/michaelB/MA_Bellmann_ DAGA2001.pdf

Bellmann, M. A., Baumann, I., Hillebrand, P., Mellert, V., Weber, R. (2001), Comfort inside cars: Effects of seat and steering -wheel vibrations, 36th United Kingdom Group Conference on Human Response to Vibration, Centre for Human Sciences, Farnborough, England, 2001. ISBN: ( 0-9541283-0-3), pp. 245 – 257, http://www.physik.uni-oldenburg.de/Docs/aku/staff/michaelB/Paper_ISVR2001_ Michael_Bellmann.pdf

Buss, S., R. Weber, W. Liederer, and V. Mellert (2001), Charakterisierung von Reifengeräuschen mit Geräuschbegriffen, DAGA 2001, Hamburg-Harburg,


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Deutschland, 2001. ISBN: (3-9804568-9-7), pp. 296/ 297. DEGA e.V., Oldenburg.

Buss, S., R. Weber, W. Liederer, and V. Mellert (2001), Subjective and objective characterization of tyre noise. INTER-NOISE 2001, Den Haag, 2001. ISBN: (90-806554-2-2), pp. 2411 - 2414. Nederlands Akoestisch Genootschap (NAG).

Podlaszewski, N., and V. Mellert (2001), Lokalisationsversuche für virtuelle Realität mit einer 6-Mikrofonanordnung, DAGA 2001, Hamburg-Harburg, Deutschland, 2001. ISBN: (3-9804568-9-7), pp. 278/ 279. DEGA e.V., Oldenburg.

Sato, S., Y. Ando, and V. Mellert (2001), Cues for localization in the median plane as extracted from the auto-correlation function, Journal of Sound and Vibration 241(1):53-56.

Atagi, J., R. Weber, and V. Mellert (2002), Effect of modulated delay time of reflection on autocorrelation function and perception of echo, Journal of Sound and Vibration 258(3):pp. 443-450, <Go to ISI>://000179523300005

Buss, Sandra, Reinhard Weber, and Werner Liederer (2002), Objektivierung des subjektiv wahrgenommenen Profilgeräuschs in Reifen-Fahrbahn-Geräuschen, DAGA 2002, Bochum, Deutschland, 2002. ISBN: (3-9804568-6-2), pp. 186/ 187. DEGA e.V., Oldenburg.

Mellert, V., I. Baumann, N. Freese, R. Kruse, R. Weber, H. Remmers, and M. Bellmann (2002), Psychophysical analysis of sound and vibration in the cabin of passenger aircrafts, J. Acoust. Soc. Am. 112(5):pp. 2243, http://ojps.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JASMAN000112000005002243000002&idtype=cvips

Weber, R., and M. Bellmann (2002), Vergleich des Booming Indexes nach hatano und Hashimoto mit anderen objektiven Signalparametern zur Charakterisierung der subjektiven Dröhnstärke, DAGA 2002, Bochum, Deutschland, 2002. ISBN: (3-9804568-6-2), pp. 180/ 181. DEGA e.V., Oldenburg.

Baumann, I., M. Bellmann, S. Buss, N. Freese, E. Groll-Knapp, S. Hallmann, Ch. König, R. Kruse, T. Leitmann, M. Meixner-Pendleton, V. Mellert, H. Remmer, M. Schöls, B. Schulte-Fortkamp, M. Trimmel, and R. Weber (2003), The assessment of load, strain and comfort of flight crew and cabin crew in a cabin simulator - test design, Euronoise 2003, Neapel, 2003. ISBN: (88-88942-00-9), pp. 1-6; paper ID: 486-IP.

Baumann, I., M. Bellmann, S. Buss, N. Faulhaber, N. Freese, E. Groll-Knapp, S. Hallmann, Ch. König, R. Kruse, T. Leitmann, V. Mellert, H. Remmers, A. Röder, B. Schulte- Fortkamp, M. Trimmel, and R. Weber (2003), HEACE: Simulation von Schall, Vibrationen und anderer Umgebungsvariablen im Kabinensimulator, DAGA 2003, Aachen, Deutschland, 2003. ISBN: (3-9808659-0-8), pp. 250/ 251. DEGA e.V., Oldenburg.

Baumann, I., M. Bellmann, S. Buss, N. Freese, E. Groll-Knapp, S. Hallmann, Ch. König, R. Kruse, T. Leitmann, V. Mellert, H. Remmers, B. Schulte- Fortkamp, M. Trimmel, and R. Weber (2003), HEACE: Versuchsdesign zur Erfassung der Belastung, der Beanspruchung und des Komforts von Passagieren und der Crew in einem Kabinensimulator, DAGA 2003, Aachen, Deutschland, 2003. ISBN: (3-9808659-0-8), pp. 252/ 253. DEGA e.V., Oldenburg.


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Bellmann, M., and H. Remmer (2003), Evaluation of vibration perception in passenger vehicles and aircrafts, Euronoise 2003, Neapel, Italien, 2003. ISBN: (88-88942-00-9), pp. 1 -6; paper ID: 489-IP.

Buss, Sandra, Reinhard Weber, and Werner Liederer (2003), Wahrnehmung des Profilgeräuschs in Reifen-Fahrbahn-Geräuschen, DAGA 2003, Aachen, Deutschland, 2003. ISBN: (3-9808659-0-8), pp. 244/ 245. DEGA e.V., Oldenburg.

Mellert, V., E. Groll-Knapp, H. Remmers, B. Schulte- Fortkamp, M. Trimmel, and R. Weber (2003), Komfort im Flugzeug - Forschungs- und Entwicklungsbedarf der EU am Beispiel HEACE, DAGA 2003, Aachen Deutschland, 2003. ISBN: (3-9808659-0-8), pp. 248/ 249. DEGA e.V., Oldenburg.

Weber, R., I. Baumann, N. Freese, R. Kruse, and V. Mellert (2003), Psychoacustic analysis of sound in the cabin of passenger aircrafts, Euronoise 2003, Neapel, 2003. ISBN: (88-88942-00-9), pp. 1-6; paper ID: 457-IP.

Bellmann, M., V. Mellert, H. Remmer, and R. Weber (2004), Influence of frequency and magnitude on the perception of vertical whole -body vibration, CFA/ DAGA '04, Strassburg, Frankreich, 2004. ISBN: (2-9521105-2-2) II, pp. 1117/1118. Société Francaise d'Acoustique, Deutsche Gesellschaft für Akustik e.V.

Bellmann, M., and H. Remmers (2004), Evaluation of vibration perception in passenger cabin, CFA/ DAGA '04, Strassburg, Frankreich, 2004. ISBN: (2-9521105-1-4) II, pp. 597/598. Société Francaise d'Acoustique, Deutsche Gesellschaft für Akustik e.V.

Bellmann, M., H. Remmers, and V. Mellert (2004), Grundlegende Experimente zur Wahrnehmung von vertikalen Ganzkörpervibrationen, Basic Experiments on the Perception of vertical Whole-Body Vibrations, In Humanschwingung (VDI - Bericht 1821). pp. 251-270. Darmstadt, Deutschland: VDI.

Buss, S., and R. Weber (2004), Subjective and objective characterisation of tonal components in tyre/ road noise, CFA/ DAGA '04, Strassburg, Frankreich, 2004. ISBN: (2-9521105-1-4) I, pp. 495/496. Société Francaise d'Acoustique, Deutsche Gesellschaft für Akustik e.V.

Hansen, H., R. Weber, T. Matsui, S. Kuwano, and S. Namba (2004), Evaluation of sound quality a.ected by tonal components in Germany and Japan, CFA/ DAGA '04, Strassburg, Frankreich, 2004. ISBN: (2-9521105-2-2) II, pp. 755/756. Société Francaise d'Acoustique, Deutsche Gesellschaft für Akustik e.V.

Kubo, N., V. Mellert, R. Weber, and J. Meschke (2004), Categorisation of Engine Sound, Inter Noise 2004, Prag, Tschechien, 2004. ISBN: (5-7325-0816-3), pp. 8 pages.

Kubo, N., V. Mellert, R. Weber, and J. Meschke (2004), Engine sound perception - Apart from so-called order analysis, CFA/ DAGA '04, Strassburg, Frankreich, 2004. ISBN: (2-9521105-2-2) II, pp. 867/868. Société Francaise d'Acoustique, Deutsche Gesellschaft für Akustik e.V.

Mellert, V., I. Baumann, N. Freese, and R. Weber (2004), Investigation of noise and vibration impact on aircraft crew, studied in an aircraft simulator, Inter Noise 2004, Prag, Tschechien, 2004. ISBN: (5-7325-0816-3), pp. 8 pages.

Mellert, V. (2004), Development of human response models of comfort, health and performance, Aircraft Interiors 2004, Hamburg, Deutschland, 2004. ISBN, pp.


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Oey, H., and V. Mellert (2004), Vibration thresholds and equal vibration levels at the human fingertip and palm, ICA 2004, Kyoto, Japan, 2004. ISBN: (4-9901915-4-4) 4, pp. 3227-3230.

Weber, R., I. Baumann, N. Freese, S. Buss, Ch. König, and V. Mellert (2004), Effects of noise on the comfort of cabin crew studied in an aircraft cabin simulator, ICA 2004, Kyoto, Japan, 2004. ISBN: (4-9901915-2-8) 2, pp. 1499-1502.

Bastian, J. (2005), Passagierkomfort in der Flugzeugkabine - Psychologische Erfassung komfortrelevanter Faktoren (2/2), DAGA '05, München, Deutschland, 2005. ISBN, pp. 2 Seiten.

Bellmann, M., J. Bastian, and R. Weber (2005), Passagierkomfort in der Flugzeugkabine(1/2) - physikalische Messung komfortrelevanter Umgebungsfaktoren, DAGA '05, München, Deutschland, 2005. ISBN, pp. 2 Seiten.

Buss, S., R. Kruse, and R. Weber (2005), Einfluss des Schalls und anderer Umgebungsvariablen auf Komfortempfinden in der Flugzeugkabine, DAGA '05, München, Deutschland, 2005. ISBN, pp. 2 Seiten.

Hansen, H., R. Weber, and U. Letens (2005), Subjektive Bewertung der Tonhaltigkeit in der Fahrzeugakustik, DAGA '05, München, Deutschland, 2005. ISBN, pp. 2 Seiten.

Kubo, N., V. Mellert, R. Weber, and J. Meschke (2005), Anwendung der Musiktheorie auf Geräuschdesign, DAGA '05, München, Deuschland, 2005. ISBN, pp. 2 Seiten.

Liebing, R., and R. Weber (2005), Subjektive Bewertung von instationären Funktionsgeräuschen in der Fahrzeugakustik, DAGA '05, München, Deutschland, 2005. ISBN, pp. 2 Seiten.


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Short report A. Mertins


Applications

The human auditory system is well adapted to analyze speech, music, and environmental sounds, and there is reason to believe that a double matching occurs, where the hearing system is matched to such common sounds and the sounds (especially speech) are matched to the hearing system. We studied this phenomenon by developing methods for the analysis and representa tion of natural sounds, with essentially two aims. The first one is to derive new technical solutions for the efficient coding of natural sounds, and the second one is to compare the found structures for the optimal representation of natural sounds with those found in the hearing system.

The generation of optimal bases and atomic decompositions for the representation of sound has been the research topic of Stefan Strahl. In these works, we used the technique of independent component analysis (ICA) to find optimal (overcomplete) basis systems for signal representation. In particular, we were interested in extending the existing results from the literature, which only look at block-wise coding, to coding with overlapping blocks. The works are in progress, and the expected outcome is a set of oversampled filterbanks that are capable of decomposing an audio stream into a number of (nearly) statistically independent sub-streams that are easy to encode and transmit through a capacity-limited channel. A second approach taken is the sparse coding in overcomplete bases using the matching and basis pursuit paradigms. In contrast to the ICA-based methods, which yield sparse coding in a statistical sense, these techniques deliver the best sparse representation for a given sample function of a random sound process and a given overcomplete basis.

A second research theme, on which Huan Zhou has been working during her postdoctoral stay, is the actual encoding of sound signals into embedded bitstreams. Here we developed a progressive coding scheme, called combined significance tree quantization (CSTQ), which is capable of efficiently dealing with the many zero-valued samples in a sparse overcomplete representation and yields a fully scalable compression scheme whose performance is comparable to non-scalable state-of-the-art techniques like MPEG’s mp3. In listening tests and in objective tests, the CSTQ coder proved to be superior to the MPEG4-BSAC scheme, which is the only standardized coder with similar functionalities. These tests with the CSTQ coder have still been done with more conventional basis representations, and current works address the combination of CSTQ with the optimal representations developed by Stefan Strahl. Moreover, ongoing works address the incorporation of auditory models into the way in which different components of an audio signal are embedded.


There are strong links between our group and the groups of Birger Kollmeier and Georg Klump. With Birger Kollmeier, we have joint projects on speech recognition and audio coding, and in particular within the InterGK, we look at the incorporation of new psychoacoustic/auditory models into audio compression and speech recognition, respectively. Moreover, with Stefan Uppenkamp we made first tests on the incorporation of independent component analysis methods into the analysis of fMRI data. The object-binding mechanisms investigated by Georg Klump’s group will form


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a basis for future work on object extraction and source separation. Moreover, we cooperated in the development of a mouse-head position tracking system, and we have developed a basic system for crosstalk cancellation of audio signals, which will be adapted to Gerbils and tested in free-field measurements.



Audio and speech coding: Zhou,H. Mertins,A. Strahl,S. An Efficient, Fine-Grain Scalable Audio Compression

Scheme 118th Audio Engineering Society Convention, Barcelona Spain (2005), Preprint No. 6435.

Strahl,S. Zhou,H. Mertins,A. An Adaptive Tree-Based Progressive Audio Compression Scheme IEEE Workshop on Applications of Signal Processing to Audio and Acoustics, New Paltz, NY (2005) - submitted

M. Raad, I. Burnett, and A. Mertins, "Multi-rate extension of the scalable to lossless PSPIHT audio coder," in Proc. Eurospeech'03, Geneva, Switzerland, Sept. 2003, pp. 1117–1120.

M. Raad, A. Mertins, and I. S. Burnett, "Scalable to lossless audio compression based on perceptual set partitioning in hierarchical trees (PSPIHT)," in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing (ICASSP2003), Hong Kong, April 2003, vol. 5, pp. 624-627, reprinted in Proc. Fourth International Conference on Multimedia and Expo (ICME 2003), Baltimore, vol. 3, pp. 393-396, July 2003.

M. Raad, I. Burnett, and A. Mertins, "Multi-rate and multi-resolution scalable to lossless audio compression using PSPIHT," in Proc. Seventh International Symposium on Signal Processing and its Applications (ISSPA 2003), Paris, France, July 2003, vol. 2, pp. 121–124.

M. Raad, A. Mertins, and I. Burnett, "Audio coding based on the modulated lapped transform (MLT) and set partitioning in hierarchical trees," in Proc. 6th World Multiconference on Systemics, Cybernetics and Informatics (SCI 2002), Orlando, FL, USA, July 2002, vol. 3, pp. 303-306.

M. Raad, A. Mertins, and I. Burnett, "Audio compression using the MLT and SPIHT," in Proc. 6th Int. Symposium on Digital Signal Processing for Communication Systems, Sydney, NSW, Australia, Jan. 2002, pp. 128-132.

M. Raad, C. Ritz, I. Burnett, and A. Mertins, "The analysis of speech codecs using psychoacoustic measures," in Proc. of the 2002 IEEE Workshop on Speech Coding (SCW2002), Tsukuba, Japan, Sept. 2002, pp. 108-110.

M. Raad and A. Mertins, "From lossy to lossless audio coding," in Proc. of the 5th Int. Conference on Digital Audio Effects (DAFx-02), Hamburg, Germany, Sept. 2002, pp. 245-250.

M. Raad, A. Mertins, and I. S. Burnett, "A scalable to lossless audio compression scheme," in Proc. 1st Workshop on the Internet, Telecommunications and Signal Processing, Wollongong, NSW, Australia, Dec. 2002, pp. 167-172.

Source Separation: I. T. Russell, J. Xi, and A. Mertins, Time domain blind separation of nonstationary

convolutively mixed signals. In Signal Processing for Telecommunications and


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Multimedia, Series: Multimedia Systems and Applications, Wysocki T, Honary B, Wysocki B (Eds.), vol. 27, pp. 15–30, Springer, 2005.

Iain Russell, Jiangtao Xi, Alfred Mertins, and Joe Chicharo, “Blind source separation of nonstationary convolutively mixed signals in the subband domain,” in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing, Montreal, Canada, May 2004, pp. V–481–V–484.

I. Russell, J. Xi, A. Mertins, and J. Chicharo, ``Integration of {DFT} and cosine-modulated filter banks with blind separation of convolutively mixed non-stationary sources,''

in Proc. 3rd IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM2004), Barcelona, Spain, July 2004.

A. Mertins and I. Russell, "An extended ACDC algorithm for the blind estimation of convolutive mixing systems," in Proc. Seventh International Symposium on Signal Processing and its Applications (ISSPA 2003), Paris, France, July 2003, vol. 2, pp. 527–530.

I. Russell, A. Mertins, and J. Xi, “Time domain optimization techniques for blind separation of non-stationary convolutive mixed signals,” in Proc. 9th IASTED Int. Conf. on Signal and Image Processing, Honolulu, Hawaii, USA, Aug. 2003.

Iain Russell, Jiangtao Xi, Alfred Mertins, and Joe Chicharo, “Blind separation of nonstationary convolutively mixed signals in the time domain,” in Proc. 7th International Symposium on DSP for Communication Systems (DSPCS03), Coolangatta, Qld, Australia, Dec. 2003, pp. 93–98.


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Short report J. B. T. M. Roerdink


fMRI time series analysis

The project “Wavelet based methods for the analysis of fMRI time series” (Ph.D. student: A.M. Wink, supervisor: J.B.T.M. Roerdink) was completed. A wavelet denoising study was published as “Denoising functional MRI time series: a comparison of wavelet denoising and Gaussian smoothing”, IEEE Trans. Medical Imaging, vol. 23. The Matlab software developed been accepted as an SPM plug-in, cf. http://www.fil.ion.ucl.ac.uk/spm/ext/#spm_wavelet. The actual distribution of the noise in fMRI data was studied. Statistical tests, analytical results and numerical computations have shown that the distribution of the difference between two images whose intensities follow a Rice distribution, can be very well approximated by a Gaussian. This study also proposed a new protocol for fMRI studies which guarantees the noise to have a normal distribution. Third, a method has been developed to extract the HRF from an fMRI time series using the Fourier-wavelet regularised deconvolution (ForWaRD) method, resulting in improved statistical significance in the analysis of fMRI time series. Wink obtained his Ph.D. degree on September 10, 2004, and is now working at the Brain Mapping Unit, University of Cambridge. A collaboration between this institute and the Neuroimaging Center Groningen on brain connectivity analysis and visualization has been initiated by Roerdink.

Visualization of multichannel EEG data

In the project “Interactive Visualization Techniques for Interpreting Functional Neuroimaging Data” (Ph.D. student: Michael ten Caat, supervisors: N.M. Maurits, J.B.T.M. Roerdink) a new visualization technique for time-varying multichannel EEG data was developed (Proc. Eurographics 2005). This method is based on parallel coordinates and a two-dimensional spatial layout based on tiles. It can be applied to arbitrary numbers of time-steps and the maximum number of channels used currently in practice, and it should be widely applicable to other time-varying multivariate data types.

Perceptual visualization

A project “Multimodal perception and visualization” (Ph.D. student: Ronald van den Berg, supervisors: F. Cornelissen, J.B.T.M. Roerdink) was started in 2004. The goal is to study general designs of visual, non-visual and multisensory transfer functions for multidimensional data, and to develop a task-related evaluation methodology based on perception-based quality metrics. As a first test case, we started a study on perceptual aspects of graph visualization techniques. These are for example relevant for two- and threedimensional visualization of biological networks, such as genetic networks and brain connectivity networks. First results have been presented at the ECVP05 and APGV05 conferences, August 2005.

Study of number processing by functional neuroimaging

Another project was started, called “A study of number processing in the brain using functional neuroimaging and the additive factor method” (Ph.D. student Meltem Ballan, supervisors: M. Lorist, N.M. Maurits, J.B.T.M. Roerdink). The objective of the


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project is to obtain a better understanding about a specific type of cognitive task, i.e. number processing, by simultaneous 32-channel EEG and fMRI registration and the Additive Factor Method (AFM). The unique combination of this method and different measurement techniques in an event-related design will increase our knowledge about methodological issues concerning experimental design and the relation between results observed with different measurement techniques.


Interactions in the form mutual discussions and consultations have taken place with several groups of the InterGK. In particular, with the biomedical engineering group (Duifhuis, Renken) on correction of spin-history artefacts in MRI data; with the ophthalmology group (Cornelissen) on visual perception and visualization; and with several of the Oldenburg groups during various InterGK meetings.



M.A. Westenberg and J.B.T.M. Roerdink (2000), Frequency Domain Volume Rendering by the Wavelet X-ray Transform, IEEE Trans. Image Processing, 9 (7), 1249-1261.

M.A. Westenberg and J.B.T.M. Roerdink (2000), X-ray volume rendering through two-stage splatting, Machine Graphics & Vision, 9 (1/2), 307-314.

M.A. Westenberg and J.B.T.M. Roerdink (2001), An Extension of Fourier-Wavelet Volume Rendering by View Interpolation, J. Math. Imag. Vision, 14 (2), 103-115.

M.H.F. Wilkinson, A.C. Jalba, E.R. Urbach and J.B.T.M. Roerdink (2002), Identification by mathematical morphology, In: Automatic Diatom Identification, Du~Buf, J. M. H. and Bayer, M. M. (eds.), Ch. 11, 221-244.

M.A. Westenberg and J.B.T.M. Roerdink (2002), Mixed-method identifications, In: Automatic Diatom Identification, Du Buf, J. M. H. and Bayer, M. M. (eds.), Ch. 12, 245-257.

J.B.T.M. Roerdink (2003), Multiresolution Maximum Intensity Volume Rendering by Morphological Adjunction Pyramids, IEEE Trans. Image Processing, , 12 (6), 653-660,

A.C. Jalba, M.H.F. Wilkinson and J.B.T.M. Roerdink (2004), Morphological hat-transform scale spaces and their use in pattern classification, Pattern Recognition, 37 (5), 901-915,

Wink, A.M. and J.B.T.M. Roerdink (2004), Denoising functional MR images: a comparison of wavelet denoising and Gaussian smoothing, IEEE Trans. Med. Imaging, 23 (3), 374-387.

A.C. Jalba, M.H.F. Wilkinson and J.B.T.M. Roerdink (2004), CPM: A Deformable Model for Shape Recovery and Segmentation Based on Charged Particles, ieeetpami, 26 (10), 1320-1335.

A.C. Jalba, M.H.F. Wilkinson and J.B.T.M. Roerdink (2004), Automatic segmentation of diatom images for classification, Microscopy Research and Technique, 65 (1-2), 72-85.


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J.B.T.M. Roerdink (2005), Morphological Pyramids in Multiresolution MIP Rendering of Large Volume Data: Survey and New Results, J. Math. Imag. Vision, 22, 143-157.

L. Muresan, R. Renken, J.B.T.M. Roerdink and Hendrikus Duifhuis (2005), Automated Correction of Spin-History Related Motion Artefacts in fMRI: Simulated and Phantom Data, IEEE Transactions on Biomedical Engineering, 52 (8), in press .

A.C. Jalba, M.H.F. Wilkinson and J.B.T.M. Roerdink (in press), Shape representation and recognition through morphological curvature scale spaces, IEEE Trans. Image Processing.

A.C. Jalba, M.H. F. Wilkinson, J.B.T.M. Roerdink, Micha M. Bayer and Stephen Juggins (in press), Automatic Diatom Identification using Contour Analysis by Morphological Curvature Scale Spaces, Machine Vision and Applications, in press.

A. Pizurica, A.M. Wink, E. Vansteenkiste, W. Philips and J.B.T.M. Roerdink (in press), A review of wavelet denoising in MRI and ultrasound brain imaging, Current Medical Imaging Reviews.


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Short report D. G. Stavenga


Adaptation in the visual system/Visual photoreceptors

Visual systems sample the optical information of the environment with their retinal array of photoreceptors. We investigated this retinal array in butterflies by combining optical, electrophysiological and computational methods. We have clarified the extreme regionalization of butterfly eyes. Especially, we have demonstrated for the first time that the photoreceptors are combined in specific spectral sets, the so-called ommatidia, and that an eye contains a number of different classes of ommatidia, dependent on the eye region. The classes are locally randomly distributed. We have developed a novel large-aperture epi-illumination microscope, which has allowed visualization and mapping of the ommatidial heterogeneity in different butterfly species. The heterogeneity in spectral characteristics is strongly correlated with colour processing, showing differences between different viewing directions and their expected spectral composition (e.g., upwards a bluish sky, and downwards a greenish earth). We have provided strong evidence that colour contrast is enhanced by a combination of optical mechanisms, including multilayer interference filters and pigments surrounding the photoreceptors.

Visual photoreceptors need to be tuned to intensity variations encountered during natural behaviour. This was studied by recording natural time series of intensities in a natural environment, and playing these series back in the laboratory whilst recording from fly photoreceptors and second-order neurons. We found that these cells are very well tuned to the wide dynamic range of natural stimuli, and we were able to develop a nonlinear systems model adequately describing their behaviour. To this end a new information theoretical method was developed for identifying neurophysiological systems and quantifying their performance.

Light adaptation and contrast gain control were also studied in the human visual system, using psychophysical techniques. The model developed in the course of these studies is at the moment probably the most adequate one in existence for the earliest stages of the human visual system. The first stage of this model is (mathematically) identical to the one developed for fly photoreceptors. This suggests that similar strategies have been developed independently by very different organisms in response to a similar challenge: how to perform gain control of widely and quickly varying light levels, under the condition of retaining as much information about the surroundings as possible.

Adaptation in the mechanosensory system/Mechanoreceptors

Considerable progress has been made in understanding signal transduction by the mechanoreceptors in the fish lateral line. Shaping of mechanical signals by the hydrodynamics of the lateral line canal organ and its accessory structures is now understood in great detail. Using our micro-laser interferometer combined with electrophysiological methods, we have shown that the mechanical filtering due to fluid-structure interactions is precisely matched to electrical filtering by the hair cells. Using the lateral line organ as a model system, we have explained some of the fundamental causes of the adverse effects that some antibiotics (aminoglycosides) have on hearing in relation to Ca++ influx.


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In addition to mechanotransduction in lateral line hair cells, we also investigated transduction in outer cochlear hair cells of mice. We have demonstrated that molecular forces involved in activation of mechano-sensitive ion channels can be directly determined from electrophysiological measurements. Using the thermodynamic properties of ionic channels a general applicable method was developed to calculate free energies and related gating forces of transducer channels in hair cells. Based on this method we have developed a detailed kinetic model for mechanical gating that is, to date, the most accurate in describing mechano-electrical transduction in mammalian hair cells.

Using mutant mouse cochlear hair cells we have demonstrated the functional role of a molecular motor molecule (Myosin 7A) in adaptation of evoked transduction current to prolonged stimulation, and proposed a mechanism to explain the relation to certain types of deafness (Usher syndrome) when the motor molecule is absent.

One of the most important achievements of the past period is the identification of a fundamental limit imposed on the accuracy of hearing by stochastic properties of mechano-transducer channels in cochlear hair cells. In combined experimental and theoretical studies we have shown that a single hair cell can transduce displacement information with an accuracy of a few nanometers. We identified the molecular gating force as the pivotal physical quantity gouverning this accuracy and demonstrated that the related mechanical nonlinearity (gating compliance) of the gating machinery is a prerequisite for mechanical information transfer, a property that is degraded in proportion to the thermal energy.

Object perception /Natural stimuli and neural processing

The statistical properties of natural images were investigated in several studies. Power spectra of natural images were shown to be inversely proportional to the square of the spatial frequency, indicative of scale invariance. Such power spectra play an important role in recent theories of vision that aim to predict properties of early vision from first principles, using information theory. In one of the largest computational studies in the field of vision research to date, we performed independent component analysis of natural images and natural image. These studies predict receptive fields similar to those found in the visual cortex of the mammalian brain. The natural images we measured for these projects constitute at the moment the largest publicly accessible database of calibrated natural images available to the vision research community. This database is utilized at present by a considerable number of investigators.

The properties of the input to an eye are not only determined by the visual environment, but also by the way the body of the organism moves, and how the head and eyes move relative to the body. In order to get access to this type of information, we developed a setup that makes it possible to follow the movements of a fly and its eyes in all degrees of freedom during (almost) free flight in a cage. From the flight path and the interior of the cage, the optical input to the eye can then be reconstructed with unprecedented detail. This is used in a recent project, where we presented the optic flow in a dedicated flight simulator to blowflies whilst recording from visual motion sensitive neurons (measurements carried out in Bielefeld in collaboration with Egelhaaf and Kern). These experiments provide essential new insight into how flying insects acquire information on self-motion from the optic flow field, and show the important role of eye movements (saccades) in that process.


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The group has a long-standing interaction with the Biomedical Technology group (H. Duifhuis) about research on audiological, hearing and acoustical problems. The group shares interests with the group of R. Weiler, partly through joint collaborations with the group of Kamermans in Amsterdam. H. van Hateren regularly interacts with the team of N. Petkov. Further interactions have been built up between Hermann Snippe and Hans v. Hateren with the physics groups in Oldenburg (Kollmeier, Verhey, Feudel) about parallels in auditory and visual processing



C.J. Kros, W. Marcotti, S.M. van Netten, T.J. Self, R.T. Libby, S.D.M. Brown, G.P. Richardson, K.P. Steel, “Reduced climbing and increased slipping adaptation in cochlear hair cells of mice with Myo 7a mutations”, Nature Neuroscience 5, 41-47 (2002)

J.E.C. Wiersinga-Post, S.M. van Netten, “Calcium influences the mechanical properties of hair cell bundles”, Bioacoustics 12, 153-156 (2002)

S.M. van Netten, J.E.C. Wiersinga_Post, ”Matched peripheral filtering in the lateral line organ and relation to temperature”, Bioacoustics 12, 156-158 (2002)

D.G. Stavenga, “Colour in the eyes of insects”, J. Comp. Physiol. A 188, 337-348 (2002a)

D. G. Stavenga, “Reflections on colourful ommatidia of butterfly eyes”, J. Exp. Biol. 205, 1077-1085 (2002b)

X. Qui, K.A.J. Vanhoutte, D.G. Stavenga, K. Arikawa, “Ommatidial heterogeneity in the compound eye of the male small white butterfly, Pieris rapae crucivora”, Cell Tiss. Res. 307, 371-379 (2002)

K.J.A. Vanhoutte, B.J.L. Eggen, J.J.M. Janssen, D.G. Stavenga, “Opsin cDNA sequences of a UV- and green rhodopsin of the satyrine butterfly Bicyclus anynana”, Insect Biochem. Molec. Biol. 32,1383-1390 (2002)

J.H. van Hateren, L. Ruttiger, H. Sun, B.B. Lee, “Processing of natural temporal stimuli by macaque retinal ganglion cells”, J. Neurosci. 22, 9945-9960 (2002)

S.M. van Netten, T. Dinklo, W. Marcotti, C.J. Kros, “Channel gating forces govern accuracy of mechano-electrical transduction in hair cells”, Proc. Natl. Acad. Sci. USA 100, 15510-15515 (2003)

K.J.A. Vanhoutte, K.F.L. Michielsen, D.G. Stavenga, “Analyzing the reflections from single ommatidia in the butterfly compound eye with Voronoi diagrams”, J. Neurosci. Methods 131, 195-203 (2003)

D.G. Stavenga, “Angular and spectral sensitivity of fly photoreceptors. I. Integrated facet lens and rhabdomere optics”, J. Comp. Physiol. A 189, 1-17 (2003)

D.G. Stavenga, “Angular and spectral sensitivity of fly photoreceptors. II. Dependence on facet lens F-number and rhabdomere type in Drosophila”, J. Comp. Physiol. A 189, 189-202 (2003)


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K. Arikawa, S. Mizuno, M. Kinoshita, D.G. Stavenga, “Coexpression of two visual pigments in a photoreceptor couses an abnormally broad spectral sensitivity in the eye of the butterfly Papilio xuthus”, J. Neurosci. 23, 4527-4532 (2003)

H.P Snippe, J.H. van Hateren, “Recovery from contrast adaptation matches ideal-observer predictions”, J. Opt. Soc. Am. A 20, 1321-1330 (2003)

J.P. Lindemann, R. Kern, C. Michaelis, P. Meyer, J.H. van Hateren, M. Egelhaaf, “FliMax, a novel stimulus device for panoramic and highspeed presentation of behaviourally generated optic flow”, Vision Res. 43, 779-791 (2003)

T. Dinklo, S.M. van Netten, W. Marcotti, C.J. Kros, “Signal processing by transducer channels in mammalian outer hair cells”, in: The biophysics of the cochlea: From molecules to Models, ed. A. Gummer, World Scientific, Singapore, 73-80 (2003)

Wakakuwa M, Stavenga DG, Kurasawa M, Arikawa K, “A unique visual pigment expressed in green, red and deep-red receptors in the eye of the small white butterfly, Pieris rapae crucivora”. J Exp Biol 207, 2803-2810 (2004)

D.G. Stavenga, S. Stowe, K. Siebke, J. Zeil, K. Arikawa, “Butterfly wing colours: scale beads make pierid wings brighter”, Proc. Roy. Soc. B 271, 1577-1584 (2004)

D.G. Stavenga, “Visual acuity of fly photoreceptors in natural conditions – dependence on UV sensitizing pigment and light-controlling pupil”, J. Exp. Biol. 207, 1703-1713 (2004)

D.G. Stavenga, “Angular and spectral sensitivity of fly photoreceptors. III. Dependence on the pupil mechanism”, J. Comp. Physiol. A 190,115-129 (2004)

H.P. Snippe, L. Poot, J.H. van Hateren, “Asymmetric dynamics of adaptation after onset and offset of flicker”, J. Vision 4, 1-12 (2004)

G. Blaj, J.H. van Hateren, “Thorax and head movements of walking flies”, J. Comp. Physiol. A 190, 861-868 (2004)

B.Curcic-Blake, S. M. van Netten, “Rapid responses of the cupula in the lateral line of ruffe (Gymnocephalus cernuus)”, J. Comp. Physiol. A 191, 393-401 (2004)

K. Arikawa, M. Kinoshita, D.G. Stavenga, “Color vision and retinal organization in butterflies”. In: Complex worlds from simpler nervous systems, ed. C. Prete, MIT Press (2004)

D.G. Stavenga, “Modern tools for studying insect eyes”. In: Advances in Insect Sensory Neuroscience, pp 159-184 ed. T.A. Christensen, CRC (2004)

G. Palasantzas, J.Th.M. De Hosson, K.F.L. Michielsen, D.G. Stavenga, “Optical properties and wettability of nanostructured biomaterials: moth-eyes, lotus leaves, and insect wings”, in: Handbook of nanostructured biomaterials and their applications, Vol. 1: Biomaterials (Nalwa HS, ed.), pp 273-301 (2004)

S. Coombs, S.M. van Netten “The biomechanics and hydrodynamics of octavolateralis sensory systems with special emphasis on the lateral line”, in: Fish physiology: Fish biomechanics, eds. G. Lauder, B. Shadwick, Academic Press (2005)

W. Marcotti, S.M. van Netten, C.J. Kros, “The aminoglycoside antibiotic dihydrostreptomycin rapidly enters hair cells through the mechano-electrical transducer channels”, J. Physiol. 567, 505-521 (2005)


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K. Arikawa, M. Wakakuwa, X. Qiu, M. Kurasawa, D.G. Stavenga, “Sexual dimorphism of short-wavelength photoreceptors in the small white butterfly, Pieris rapae crucivora”, J. Neurosci. 25, 5935-5942 (2005)

Dissertations

K.J.A. Vanhoutte, “Butterfly visual pigments: molecular cloning and optical reflections”, 2003.

M. Postma, “Spatial and temporal aspects in biological signal transduction. Diffusion, reaction and geometry in Drosophila phototranduction and Dictyostelium chemotaxis” , 2003.

R. C. Smallegange, “Attractiveness of different light wavelengths, flicker frequencies and odours to the housefly (Musca domestica L.)” , 2003.

G. Blaj, “Walking and vision in blowflies”, 2004.

T. Dinklo, “Mechano- and electrophysiological studies on cochlear hair cells and superfical lateral line cupulae”, 2005.


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Short report J. L. Verhey


Adaptation in the auditory system

Within the context of adaptation we have investigated temporal effects in loudness perception and the perception of amplitude modulated sounds.

Whereas loudness of stationary signals can be predicted reasonably well by existing loudness models, loudness of temporally varying sounds is still not fully understood. We showed that loudness of fluctuating sounds depends on the frequency of envelope modulation and on the signal bandwidth (Grimm et al., 2002). In addition, we showed that spectral loudness summation is different for short signals compared to long (stationary) signals at medium levels (Verhey and Kollmeier, 2002). In a recent study, we observed a duration dependent spectral loudness summation up to high levels, whereas at low levels the effect of duration on spectral loudness summation decreases (Anweiler and Verhey, submitted). Preliminary data with hearing impaired subjects indicate on average no duration dependent spectral loudness summation.

Many aspects of masking effects in the envelope frequency domain can be accounted for by assuming a decomposition of the linear envelope with a band of modulation filters similar to the spectral selectivity in the audio frequency domain. However, some new data with complex modulations indicate interactions of widely separated modulation frequencies. In cooperation with the DFG Schwerpunktprojekt “Zeitgebundene Verarbeitung im zentralen auditorischen System” we showed that these phenomena could be predicted with a model that takes second-order modulations (referred to as venelope) into account (Ewert et al., 2002, Verhey et al., 2003). This work is currently extended by Stephan Heise in his PHD project.

Object perception in the auditory system

Object perception is linked to the ability of the auditory system to compare information across frequency. One phenomenon related to object binding is comodulation masking release (CMR). In CMR experiments it is observed that masking of a broadband masker on a sinusoidal signal can be markedly reduced if the masker is coherently modulated across frequency. Although the psychoacoustical phenomenon is already known for more than two decades the underlying mechanisms are still unclear (see Verhey et al., 2003 for an overview). Recently, we have investigated the possible role of wideband inhibition on the level of the cochlear nucleus in CMR. We found that a large amount of units in the dorsal part of the cochlear nucleus show an enhanced signal representation for a comodulated maskers, if masker components fall into the inhibitory areas of the unit (Neuert et al., 2004). Broadband inhibition can extend over several octaves, a spectral range only considered by one psychoacoustical study (Cohen, 1991). We have extended her study and found that CMR can also be observed over a three-octave range when a more conservative measure of CMR is used than in the Cohen (Ernst and Verhey, submitted). In addition we quantified the masking of off-frequency masker components on the signal and discussed on the basis of the results the possible role of changes in the envelope distribution due to the presence of the off-frequency masker in CMR experiments (Ernst and Verhey, submitted). Apart from common


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modulation also pitch is an important cue for object binding. We showed that units in the dorsal part of the mammalian cochlear nucleus could provide the relevant pitch information if their best frequency is low enough (Neuert et al., 2005).


There is a strong link between my group and other members of the InterGK since several projects include psychoacoustics or are motivated by effects observed in psychoacoustics. I am co-supervisor of two PhD projects of the group of B. Kollmeier on human psychoacoustics (M Nitschmann, S Emiroglu). Based on my recent psychoacoustical study on asymmetry of masking in humans (Verhey, 2002) the group of G Klump performed some behavioural (see Langemann and Klump, submitted) as well as physiological experiments on this effect in starlings using a subset of conditions used in psychoacoustics. We are currently working together on the modelling of the physiological data measured by M Bee. I could also provide some input with respect to literature and current ideas on signal detection strategies in those conditions to the group of U Feudel, who work on neural modelling of the psychoacoustical effect comodulation detection difference (see Buschermöhle et al., submitted).



Neuert V, Verhey JL, Winter IM (2005) “Temporal representation of the delay of iterated rippled noise in the dorsal cochlear nucleus” J Neurophysiology 93, 2766-2776

Neuert V, Verhey JL, Winter IM (2004) “Responses of Dorsal Cochlear Nucleus Neurons to Signals in the Presence of Modulated Maskers” J Neuroscience 24, 5789-579

Verhey JL, Pressnitzer D, Winter IM (2003) “The psychophysics and physiology of comodulation masking release” Exp. Brain Res. 153, 405-417

Verhey JL, Ewert SD, Dau T (2003) “Modulation masking produced by complex tone modulators” J Acoust Soc Am 114, 2135-2146

Grimm G, Hohmann V, Verhey JL (2002) “Loudness of fluctuating sounds” Acustica/ acta acustica 88, 359-368

Ewert SD, Verhey JL, Dau T (2002) “Spectro-temporal processing in the envelope-frequency domain” J Acoust Soc Am 112, 2921-2931


Anweiler AK, S, Verhey JL (submitted) “Spectral loudness summation as a function of duration and level” submitted to J Acoust Soc Am

Ernst S, Verhey JL (submitted) “Temporal representation of the delay of iterated rippled noise in the dorsal cochlear nucleus” submitted to Acta Acustica united with Acustica

Damaschke J, Verhey JL, Kollmeier, B (submitted) “Adaptation mechanisms of the precedence effect in situations with multiple reference presentations” submitted to Hearing Research


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Damaschke J, Verhey JL, Kollmeier, B (submitted) “Lateralization versus discrimination performance in click pairs provoking the precedence effect” submitted to Acta Acustica united with Acustica

Proceedings

Verhey JL, Ernst S, Neuert V, Winter IM (2005) Broadband inhibition at the level of the mammalian cochlear nucleus as a possible mechanism for comodulation masking release COSYNE ’05, 284

Ernst S, Verhey JL (2005) “Frequenzübergreifende Prozesse bis zu 4 Oktaven” Fortschritte der Akustik DAGA '05

Anweiler AK, Verhey JL (2005) “`Lautheitssummation für kurze und lange SIgnale bei Schwerhörenden” Annual meeting of the german audiological society DGA ‘05

Verhey JL, Neuert V, Winter IM (2004) “Response of single units in the mammalian cochlear nucleus to iterated rippled noise with negative gain” Assoc. Res. Otolaryngol. Abs. 27, 309

Verhey JL, Ewert S, Dau T (2003) “Processing of complex amplitude modulation in normal-hearing and hearing impaired subjects” Assoc. Res. Otolaryngol. Abs. 26, 217

Winter IM, Neuert V, Verhey JL (2003) “Across-channel processing in the mammalian dorsal cochlear nucleus” In Pressnitzer, D, DeCheveigne, A, McAdams, S, and Collete, L. (eds) Auditory Signal Processing: Physiology, Psychophysics, models, Springer New York

Neuert, V, Verhey JL, Winter IM (2003) “Comodulation masking release and the role of wideband inhibition in dorsal cochlear nucleus” Assoc. Res. Otolaryngol. Abs. 26, 241


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Short report R. Weiler


Adaptation in the retinal network

a) Neuromodulatory role of retinoic acid In the context of mechanisms of neuronal adaptation in the retina we analyzed the neuromodulatory role of retinoic acid (RA) on the molecular level.

In previous studies it was demonstrated that RA mimics effects of steady background illumination on horizontal cells of the retina, i.e. spinule formation or reduction of electrical coupling (Weiler et al., 1998; Pottek & Weiler, 2000). Although it was shown that decoupling of horizontal cells in the fish retina is mediated by a membrane-bound retinoic acid receptor-like binding site and a nongenomic pathway (Zhang & McMahon, 2000), the exact molecular mechanisms of the retinoic acid pathway were still unknown. Therefore RA-binding proteins in the fish retina were analyzed by means of receptor binding studies. These studies revealed the existence of a high-affinity membrane binding site in the carp retina. This binding site showed a unique pharmacology compared to the retinoid receptors or other known RA-binding proteins. Using a photoaffinity labeling assay we could demonstrate the existence of a RA-binding membrane protein (43 kDa). Tritiated RA-binding by this protein was partially inhibited by unlabeled RA as well as by an antibody directed against the human retinoic acid receptor α (anti-RARα). The analysis of the distribution of anti-RARα-immunoreactive proteins in the carp retina showed weak immunoreactivity in photoreceptor outer segments and stronger anti-RAR? -immunoreactivity at the dendritic tips and in or around the nuclei of cone horizontal cells. Immunoblotting detected two specific anti-RARα-immunoreactive membrane proteins (43 kDa and 46 kDa) in horizontal cell fractions of the carp retina. Since the RA-binding 43 kDa protein interacted with the retinoic acid receptor antibody, it seemed likely that the RA-binding and the anti-RARα-immunoreactive 43 kDa proteins were identical. Therefore the anti-RARα-immunoreactive 43 kDa was isolated by means of 2D gel electrophoresis and identified by means of mass spectroscopy (MudPIT). The unexpected result of the identification was that the putative mediator of the RA effects on horizontal cell physiology was an enolase-like protein. Since no interaction between RA and enolase has yet been described, the analysis of this interaction should be the content of further investigations.

b) Spatial properties of the horizontal cell network in the mammalian retina A prominent example of adaptation is evident in the horizontal cell network. Horizontal cells are coupled to each other by gap junctions, and this coupling is modulated by ambient light via several neurotransmitter pathways, including retinoic acid and dopamine. The subunit composition of the gap junction channel determines its physiological properties, such as permeability and gating, so identifying the connexin that makes up the horizontal cell gap junctions is an important step in uncovering the molecular mechanisms underlying this adaptive process. Using a mouse line in which the connexin 57 (Cx57) coding region was deleted and replaced by a lacZ reporter gene, our group collaborated with the Willecke laboratory at the University of Bonn to show that Cx57 is expressed exclusively by horizontal cells in the mouse retina, and tracer coupling is significantly reduced in Cx57-deficient mice (Hombach et al. 2004).


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We have developed a technique for recording intracellularly from mouse horizontal cells in the eyecup preparation. Using this approach, we characterized the receptive field properties of wildtype mouse horizontal cells. We found that the length constant depended on stimulus intensity, as had been reported previously for other species. Comparison of the receptive field sizes of horizontal cells from wildtype and Cx57-deficient mice confirmed the role of Cx57 in electrical coupling of the horizontal cell network.

c) Characterization of ganglion cell networks Ganglion cells transmit their signals by way of the optic nerve to the brain. At first glance it appears that their spatial distribution sets the spatial resolution of the visual system. However, many ganglion cells form coupled networks, which is counterintuitive to this assumption. The coupled networks are formed by gap junctions, and the aim of this work was to identify proteins that form electrical synapses between neurons in the mouse retina. Proteins that form electrical synapses belong to the family of connexins (Cx). The investigated alpha-ganglion cells are considered to be alert cells, essential for shifting visual attention. Furthermore, bistratified ganglion cells, which are considered to be responsible for motion direction-selective light responses, were studied.

Our results demonstrate that coupling patterns of distinct neuron types vary in shape and size. Additionally, connexin expression is neuron type specific: alpha-ganglion cell coupling uses Cx36, whereas coupling of direction-selective ganglion cells requires electrical synapses containing Cx45. Recent reports provided evidence that different connexins form synapses with unique and specific biophysical properties. Based on these findings, it is suggested that neuron type-specific expression of connexins determines the intercellular communication within the networks.



Schubert T, Maxeiner S, Krüger O, Willecke K, Weiler R (2005) Connexin45 mediates gap junctional coupling of bistratified ganglion cells in the mouse retina. J. Comp. Neurol. (in press)

Schubert T, Degen J, Willecke K, Hormuzdi S, Sheriar G, Monyer H, Weiler R (2004) Connexin36 mediates gap junctional coupling of alpha-ganglion cells in mouse retina. J. Comp Neurol. 485: 191-201

Dirks P, Tieding S, Schneider I, Mey J, Weiler R (2004) Characterization of retinoic acid neuromodulation in the carp retina. J. Neurosci. Res. 15: 177-185

Hombach S, Schubert T, Söhl G, Janssen-Bienhold U, Schultz K, Büssow H, Ott T, Weiler R, Willecke K (2004) Connexin57 deficient mice with lacZ reporter gene reveal functional expression of connexin57 exclusively in horizontal cells of the retina. Eur. J. Neurosci. 19: 2633-2640

Schubert T. and A. Akopian (2004) Actin filaments regulate voltage-gated ion channels in salamander retinal ganglion cells. Neuroscience 125: 583-590

Pottek M, Hoppenstedt W, Janssen-Bienhold U, Schultz K., Perlman I, Weiler R (2003) Contribution of connexin26 to electrical feedback inhibition in the turtle retina. J. Comp. Neurol. 466: 468-477


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Bornstein O, Twig G, Benda J, Weiler R, Perlman I (2002) Dynamic changes in the receptive fields of L1-type horizontal cells in the retina of the turtle Mauremys caspica. Vis. Neurosci. 19: 621-632

Abstracts

Feigenspan A., Schubert T., and Weiler R. (2005). Intracellular Calcium Is Regulated By Different Pathways in Horizontal Cells of the Mouse Retina Invest. Ophthalmol. Vis. Sci. 2005 46: E-Abstract 1121

Schubert T., Weiler R. and Feigenspan A. (2005). Intracellular calcium is regulated by different pathways in horizontal cells of the mouse retina. 6 th Meeting of the German Neuroscience Society. Goettingen, Germany

Shelley, J, Dedek, K, and Weiler, R (2005) Effects of Connexin57 Deletion on Horizontal

Cell Receptive Field Size in the Mouse Retina. Invest. Ophthal. Vis. Sci. 46:E-abstract 600.

Shelley, J, Dedek, K, Schultz, K, Dirks, P, Schuldt, A, Janssen-Bienhold, U, and Weiler, R

(2005) Expression of Connexins in Horizontal Cells of the Mouse Retina. Proceedings of the 6th Meeting of the German Neuroscience Society/ 30th Göttingen Neurobiology Conference

2005 eds. H. Zimmerman and K. Krieglstein Neuroforum 2005, 1 Suppl. abstract 167B.

Schubert T., Weiler R. and Feigenspan A. (2004). Intracellular calcium is regulated by different pathways in horizontal cells of the mouse retina. Vision down under meeting. Fraser Island, Australia

Schubert T. (August, 2004). Gap junctional coupling of distinct neuron types is mediated by different connexins in the mouse retina. International Congress of Eye Research, Sydney, Australia

Shelley, J, Hombach, S, Schultz, K, Willecke, K, and Weiler, R (2004) Morphology of the Cx57-lacZ Mouse Retina. Meeting of the Federation of American Societies for Experimental Biology: Retinal Neurobiology.

Janssen-Bienhold U., Kirsch T., Schubert T., Söhl G., Maxeiner S., Willecke K. and Weiler R. (2003). Cellular expression of connexin45 in the mouse retina. 5 th Meeting of the German Neuroscience Society. Goettingen, Germany

Schubert T., Söhl G., Maxeiner S., Willecke K. and Weiler R. (2003). Bistratified ganglion cell coupling is mediated by Cx45. Neuroscience meeting. New Orleans, USA

Schubert T., Weiler R. and Akopian A. (2003). Actin filaments modulate voltage-gated calcium channels in retinal ganglion cells. 5 th Meeting of the German Neuroscience Society. Goettingen, Germany

Schütte, FH, Janssen-Bienhold, U, Weiler, R (2003). Identification and characterization of retinoic acid-binding proteins in the carp retina. Proceedings of the 29th Göttingen Neurobiology Conference and the 5 th Meeting of the German Neuroscience Society2003. Elsner, N & Zimmermann, H (eds). Thieme, Stuttgart, New York: p 514.


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Schütte, FH, Janssen-Bienhold, U, Weiler, R, (2003). Identification and characterization of retinoic acid-binding proteins in the carp retina. IOVS 44: E-Abstract 3513.

Schubert T. and Weiler R. (2002). Cx36 mediates coupling of OFF-alpha-ganglion cells in the mouse retina. FASEB meeting. Saxtons River, USA

Schubert T. and Weiler R. (2002). Coupling of alpha-ganglion cells in the mouse retina. FENS meeting. Paris, France

Schütte, F, Janssen-Bienhold, U, Weiler, R (2002). Identification and characterization of retinoic acid-binding proteins in the fish retina. 3rd Forum of European Neuroscience: p. 296.

Akopian A., Schubert T. and Weiler R. (2001). Glutamate induced calcium accumulation in salamander retinal neurons. ARVO meeting. Ft. Lauderdale, USA

Schubert T., Akopian A. and Weiler R. (2001). Glutamate receptor activation increases intracellular calcium levels of salamander third order neurons. 4 th Meeting of the German Neuroscience Society. Goettingen, Germany


The links within the InterGK were manifold: we particularly profited from the theoretical and modeling knowledge, which gave us valuable insights for the analysis of our data. On the other hand our contribution to the group included our broad anatomical and molecular knowledge and a wide range of techniques. This knowledge transfer was achieved not only on an individual basis but also in technical workshops and seminars. These presentations certainly broadened the perspective of all participants and form one of the important values of the InterGK. There are not many places in neurosensory research where such an intense interaction takes place. These interactions eventually led to the formulation of a joint research proposal for a Forschergruppe.

There was also a direct project-related interaction between our group and the laboratory of Dr. Klump focusing on the role of electrical coupling of GABAergic interneurons.

progress report of /bericht des applications”...

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