workshop: erp testing -...
TRANSCRIPT
Workshop: ERP Testing©
DOE 993511NIH R01 HL0100602 NIH R01 DC005994 NIH R41 HD47083NIH R01 DA017863NASA SA42-05-018NASA SA23-06-015
Dennis L. Molfese, Ph.D.University of Nebraska - Lincoln
Friday, January 14, 2011
Workshop Goals
Friday, January 14, 2011
Workshop Goals
Concepts & Definitions
Friday, January 14, 2011
Workshop Goals
Concepts & DefinitionsCommon Practices
Friday, January 14, 2011
Workshop Goals
Concepts & DefinitionsCommon PracticesAnalysis Approaches
Friday, January 14, 2011
Workshop Goals
Concepts & DefinitionsCommon PracticesAnalysis ApproachesDealing with Artifacts
Friday, January 14, 2011
Workshop Goals
Concepts & DefinitionsCommon PracticesAnalysis ApproachesDealing with ArtifactsProblem Solving
Friday, January 14, 2011
Friday, January 14, 2011
Workshop Daily Schedule
ERP Theory, Methodology, IssuesElectrode issuesArtifactsEquipmentVideos -
Unpack & Setup ERP SystemElectrode Net ApplicationNet Station Operation
Day 1
Friday, January 14, 2011
Preprocessing of ERP DataData Management & AnalysesVideos -
Packing up ERP System
Day 2
Workshop Daily Schedule
Friday, January 14, 2011
Ultimate Goal
You Become An Independent Neuroscience Investigator who can:1. Design & conduct independent studies.2. Develop the Skills to run data analyses.3. Draft and submit imaging manuscripts.4. Develop grant applications.5. Revolutionize your major field of study.
6
Friday, January 14, 2011
The Training Plan
1. Two-day ERP workshop2. Experiment planning session(s)3. Hands-on training on ERP equipment4. Conducting YOUR experiment5. Data Analysis Assistance6. Manuscript Development Assistance7. Grant Application Assistance
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1.Overview of ERP Theory, Methodology & Issues.
8
Why ERPs?
Correlation with cognitive & physiological eventsTime resolution (ms)Spatial resolutionPortabilityNo age limitsUseful with or without behavioral responseCost
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General Methodology Principles
Friday, January 14, 2011
General Methodology Principles
Same as in any research:
Friday, January 14, 2011
General Methodology Principles
Same as in any research:Screen & control participant variables
Friday, January 14, 2011
General Methodology Principles
Same as in any research:Screen & control participant variablesControl stimulus & experimental factors
Friday, January 14, 2011
General Methodology Principles
Same as in any research:Screen & control participant variablesControl stimulus & experimental factorsData quality
Friday, January 14, 2011
General Methodology Principles
Same as in any research:Screen & control participant variablesControl stimulus & experimental factorsData qualityDatabase
Friday, January 14, 2011
General Methodology Principles
Same as in any research:Screen & control participant variablesControl stimulus & experimental factorsData qualityDatabaseData analyses
Friday, January 14, 2011
General Methodology Principles
Same as in any research:Screen & control participant variablesControl stimulus & experimental factorsData qualityDatabaseData analysesReplication
Friday, January 14, 2011
ERPs
HistoryDefinitionsElectrodesTesting IssuesApplications
Friday, January 14, 2011
Where we have come from....
11
1890s
Friday, January 14, 2011
Where we have come from....
12
1950s
Friday, January 14, 2011
Where we have come from....
13
OscilloscopeTracings &Photographs
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14
1970s
Where we have come from....
Friday, January 14, 2011
15
Where are we now....
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ERPs to CVC WordsBelow Average Readers Average Readers Above Average Readers
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Event-Related Potentials
Friday, January 14, 2011
Event-Related Potentials
ERP
Friday, January 14, 2011
Event-Related Potentials
ERPPortion of Ongoing EEG
Friday, January 14, 2011
Event-Related Potentials
ERPPortion of Ongoing EEG
Time-Locked to Stimulus Onset
Friday, January 14, 2011
Event-Related Potentials
ERPPortion of Ongoing EEG
Time-Locked to Stimulus OnsetTemporal Information
Friday, January 14, 2011
Event-Related Potentials
ERPPortion of Ongoing EEG
Time-Locked to Stimulus OnsetTemporal Information
Spatial Information
Friday, January 14, 2011
Event-Related Potentials
ERPPortion of Ongoing EEG
Time-Locked to Stimulus OnsetTemporal Information
Spatial InformationComparability across the lifespan
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EEG Activity
Friday, January 14, 2011
Friday, January 14, 2011
Sampling (Digitizing) Rates
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms Sample 1/2 - 1 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms Sample 1/2 - 1 ms
Cognitive components 65 - 1000 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms Sample 1/2 - 1 ms
Cognitive components 65 - 1000 ms Peak Duration 20 - 100 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms Sample 1/2 - 1 ms
Cognitive components 65 - 1000 ms Peak Duration 20 - 100 ms Sample 4 - 5 ms
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms Sample 1/2 - 1 ms
Cognitive components 65 - 1000 ms Peak Duration 20 - 100 ms Sample 4 - 5 ms
CNV - Contingent Negative Variation 2 S - 10 S
Friday, January 14, 2011
Sampling (Digitizing) Rates
Brain Stem Evoked Response (BSER) 1 - 15 ms Peak Duration 1 - 1.5 ms 5-7 peaks to resolve Sample 1/5 - 1/10 ms
Middle Latency Response 15 - 65 ms Peak Duration 3 - 5 ms Sample 1/2 - 1 ms
Cognitive components 65 - 1000 ms Peak Duration 20 - 100 ms Sample 4 - 5 ms
CNV - Contingent Negative Variation 2 S - 10 S Peak Duration 5 - 10 S
Friday, January 14, 2011
ERPs - Extracellular
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Event Related Potentials (ERPs)
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive-negative fluctuations.
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive-negative fluctuations.
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive-negative fluctuations.
Measures:
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive-negative fluctuations.
Measures: ! (1) peak latency from evoking stimulus onset (ms)
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive-negative fluctuations.
Measures: ! (1) peak latency from evoking stimulus onset (ms)! (2) peak amplitude in microvolts µV
Friday, January 14, 2011
Event Related Potentials (ERPs)
Time-locked to an evoking or eliciting event or stimulus.
Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive-negative fluctuations.
Measures: ! (1) peak latency from evoking stimulus onset (ms)! (2) peak amplitude in microvolts µV (3) polarity (deflection from baseline to + or -)
Friday, January 14, 2011
Definitions for ERP displays x-axis
horizontal abscicca time - ms
y-axis vertical ordinate voltage amplitude - µV
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N1
P2
N2
P3
N3
P1
P4
ERP Nomenclature
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After Desmedt, 1974
ERP Nomenclature
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Display Positive vs. Negative Up
Friday, January 14, 2011
Display Positive vs. Negative Up
Arbitrary
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Display Positive vs. Negative Up
ArbitraryTradition: 70% show Negative Up
Friday, January 14, 2011
Display Positive vs. Negative Up
ArbitraryTradition: 70% show Negative Up
Friday, January 14, 2011
Display Positive vs. Negative Up
ArbitraryTradition: 70% show Negative Up
Creates some confusion in comparing work across studies
Friday, January 14, 2011
Display Positive vs. Negative Up
ArbitraryTradition: 70% show Negative Up
Creates some confusion in comparing work across studies
Friday, January 14, 2011
Display Positive vs. Negative Up
ArbitraryTradition: 70% show Negative Up
Creates some confusion in comparing work across studies
Good to practice inverting waves to gain rapid visual recognition of peaks
Friday, January 14, 2011
Display Positive vs. Negative Up
Positive Up Negative Up
+ -
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Display Positive Up
.3 - 100 Hz
60 Hz Notch
Friday, January 14, 2011
.3 - 100 Hz
60 Hz Notch
Display Positive Down
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Variations in ERPs Trial by Trial
30
10 trials selected every 10 trials across 100 trials
500 ms
Note amplitude
Variations inAmplitude &Latency
ALPHA
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Peak Latency Variations Produce Different Width Peaks Peak Amplitude Variations Produce Different Size Peaks
More Latency Shift Less Latency Shift
Friday, January 14, 2011
ERP Temporal - Spatial Dynamics
Friday, January 14, 2011
ERP Temporal - Spatial Dynamics
Assess effects that differ in:
Friday, January 14, 2011
ERP Temporal - Spatial Dynamics
Assess effects that differ in:
Friday, January 14, 2011
ERP Temporal - Spatial Dynamics
Assess effects that differ in:
•Time (ms)
Friday, January 14, 2011
ERP Temporal - Spatial Dynamics
Assess effects that differ in:
•Time (ms)•Scalp region distribution (2-D scalp
surface space)
Friday, January 14, 2011
ERP Temporal - Spatial Dynamics
Assess effects that differ in:
•Time (ms)•Scalp region distribution (2-D scalp
surface space)•Dipole effects (Time and 3-D space)
Friday, January 14, 2011
Basic Measurements
Amplitude Peak amplitude (maximum/minimum point) Mean peak amplitude (average # of points)
Latency Peak latency (maximum/minimum point) Mean peak latency (average # of time points)
Area (Under the Curve) Area for specific region
33
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ERP Amplitude & Latency Measures
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Amplitude Peak amplitude
(maximum/minimum point)
Mean peak amplitude (average # of points)
35
Basic Measurements
Friday, January 14, 2011
Latency Peak latency
(maximum/minimum point)
Mean peak latency (average # of time points)
36
Basic Measurements
Friday, January 14, 2011
Area (Under the Curve) Area for specific region 50% area (midpoint)
37
a b c c
50%
Basic Measurements
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Peak & Latency Analysis
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Pros: Traditional approach Appears straight forward & logical
Cons:- Peaks are not always clear- Developmental issues (changes in latency & amplitude)- Latency shift across scalp & subjects- Subjective judgments- Variations in criteria across journal reports- Very time consuming in training & execution- Replication problems within/across labs- Inter-rater reliability (typically not conducted/reported)
Peak & Latency Analysis
Friday, January 14, 2011
Peak & Latency Analysis
Friday, January 14, 2011
Sample Neonate Responses
41
Friday, January 14, 2011
ERPs & Averaging
42
Individual (single trial) ERPs are VERY small- depends on age (e.g., ~.5 to 30µV)
Amplifier/environmental noise are large- varies across amps & manufacturers and models- ~10 µV RMS (same size to 20x larger than single trial ERP)
Thus, single trial ERPs can be OBSCURED by large electrical events, i.e., amplifier noise, environmental signals, artifacts
TO SOLVE PROBLEM:Repeat same stimulus & average resultant single trial ERPs together to increase S/N ratio to improve ERP (signal) quality.
S/N = Signal-to-Noise-Ratio
Friday, January 14, 2011
43Goff, 1971
ERPs & Averaging
Friday, January 14, 2011
44
ERP noise level varies with number of trials tocreate the average
- square root “law” (conservative)- noise level = square root of the number of trials: 9 trials = 32 or 33.33% of signal could be noise 16 trials = 42 or 25.00% of signal could be noise 25 trials = 52 or 20.00% of signal could be noise 36 trials = 62 or 16.67% of signal could be noise 49 trials = 72 or 14.29% of signal could be noise 64 trials = 82 or 12.50% of signal could be noise 81 trials = 92 or 11.11% of signal could be noise100 trials = 102 or 10.00% of signal could be noise
ERPs & Averaging
Friday, January 14, 2011
45
Relation of Trials to Signal Noise
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8
ERP Signal Improvement
Nu
mb
er
of
Tri
als
in
Ave
rag
e
# Trials per Average
% of ERP that is Noise
Trade-off between improving S/N and completing an experiment.
ERPs & Averaging
Friday, January 14, 2011
Average ERP obtained early during test differs from later in the same test period.
46
Trial #s combinedto make averageERP
Reference =linked mastoids
First 25 Trails
Last 25 Trails
Friday, January 14, 2011
The MORE trials presented, the better the S/N ratio.
The MORE trials presented, the LONGER the test session.
The LONGER the test session, the LESS LIKELY the infant/child will complete session.
The LONGER the test session, the LESS LIKELY later ERPs will resemble earlier trial ERPs.
The REAL key to testing populations is to obtain the best S/N ratio without overtaxing the subject (e.g., infant, child, adult).
ERPs & Averaging
Friday, January 14, 2011
“ba”
Another Way To Look At ERPs
Friday, January 14, 2011
IncreasingPositiveVoltage
IncreasingNegativeVoltage
Yellow
Dark Blue
Purple
Red
Friday, January 14, 2011
Neonate ERP to Speech Syllable
Yellow
Dark Blue
Purple
Red
Friday, January 14, 2011
Adult ERP to Speech Syllable
Yellow
Dark Blue
Purple
Red
Friday, January 14, 2011
QUESTIONS ???
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Friday, January 14, 2011
Dipoles
Friday, January 14, 2011
Dipoles
a) Dipole used as description of ERP generation.
Friday, January 14, 2011
Dipoles
a) Dipole used as description of ERP generation.
Friday, January 14, 2011
Dipoles
a) Dipole used as description of ERP generation.
b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular
Friday, January 14, 2011
Dipoles
a) Dipole used as description of ERP generation.
b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular
to scalp surface).
Friday, January 14, 2011
Dipoles
a) Dipole used as description of ERP generation.
b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular
to scalp surface).
Friday, January 14, 2011
Dipoles
a) Dipole used as description of ERP generation.
b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular
to scalp surface).
c) Reflects differences in soma and dendrite ion flow across cortical layers.
Friday, January 14, 2011
Dipoles
Friday, January 14, 2011
d) Model activity.
Dipoles
Friday, January 14, 2011
d) Model activity.
Dipoles
Friday, January 14, 2011
d) Model activity.
e) Activity at scalp not necessarily result of ion movements immediately below electrode.
Dipoles
Friday, January 14, 2011
d) Model activity.
e) Activity at scalp not necessarily result of ion movements immediately below electrode.
Dipoles
Friday, January 14, 2011
d) Model activity.
e) Activity at scalp not necessarily result of ion movements immediately below electrode.
f) Caution: Dipoles generated in one hemisphere may generate higher shifts in other hemisphere.
Dipoles
Friday, January 14, 2011
Low GRTR Scores 1-dipole Model 200 ms
Match Mismatch -1.600
-1.400
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0
0.200
0.400
0 36 72 108 144 180 216 252 288 324 360 396 432 468 504 540 576 612 648 684
Friday, January 14, 2011
High GRTR Scores2-dipole Model 200 ms
Match Mismatch -1.600
-1.400
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0
0.200
0.400
0 36 72 108 144 180 216 252 288 324 360 396 432 468 504 540 576 612 648 684
Friday, January 14, 2011
3/1/01 5/2/01
SENSE
Left Hand Right Hand Left Hand Right Hand
Are Dipoles “Real” ?
Friday, January 14, 2011
58
Lantz, G., Grave de Peralta, R., Spinelli, L., Seeck, M., & Michel, C. M. (2003). Epileptic source localization with high density EEG: How many electrodes are needed? Clinical Neurophysiology, 114, 63-69.
Michel, C. M., Lantz, G., Spinelli, L., Grave de Peralta Menendez, R., Landis, T., & Seeck, M. (2004a). 128-channel EEG source imaging in epilepsy: Clinical yield and localization precision. Journal of Clinical Neurophysiology.
Michel, C. M., Murray, M. M., Lantz, G., Gonzalez, S., Spinelli, L., & Grave de Peralta, R. (2004b). EEG source imaging. Clinical Neurophysiology, 115, 2195-2222.
Tucker, D. M., Luu, P., Frishkoff, G., Quiring, J. M., & Poulsen, K. (2003). Corticolimbic response to negative feedback in clinical depression. Journal of Abnormal Psychology, 112, 667-678.
QUESTIONS ???
Friday, January 14, 2011
Digitizing Rate
How fast to sample the ERP signal? Convention = 250 Hz (4 ms intervals) Ultimately dependent on signal
characteristics
59
Friday, January 14, 2011
Nyquist's theorem: Analog waveform may be uniquely reconstructed, without error, from samples taken at equal time intervals. Sampling rate must be equal to, or greater than, twice the highest frequency component in the analog signal (3x works better).
Example: 9 Hz wave sampled 9 times/Sec = 1 Hz waveformFriday, January 14, 2011
Alias - appear as more energy (higher amplitude) at lower frequency
Nyquist - 9 Hz signal
Sampled at 14 Hz
Yields 4.5 Hz Signal
Sampled at 29 Hz
Yields 9 Hz Signal
Friday, January 14, 2011
62
Srinivasan, Tucker & Murias, 1985
Nyquist - Signal is sum of Sinusoidal Frequencies of 6.5, 10, 19 Hz
Friday, January 14, 2011
How Many Electrodes Should You Use ?
Depends on :Research Question.Availability of Equipment.
Source Localization AND Scalp DistributionStudies ALWAYS require LARGE number ofElectrodes adults = 256 infants = 128
Friday, January 14, 2011
Resolution of Scalp Signals
64
Simulationof Infant &Child ScalpERP Signals.
Simulationof Adult ScalpERP Signals.
Friday, January 14, 2011
If spatial sampling is too sparse, high spatial details will alias into low spatial frequencies, distorting topographic maps & source localization !
Srinivasan, Tucker & Murias, 1985
7 cm
Friday, January 14, 2011
66
The smallest topographic feature that can beresolved accurately by a 32-channel array is 7 cm in diameter - about the size of an ENTIRE lobe of the brain !!!
Nyquist
Friday, January 14, 2011
67
QUESTIONS ???
Friday, January 14, 2011
Impedance
Before lab computers EEG quality depended on paper recorded signal.
Noise from power lines (50 or 60 Hz) difficult to separate once introduced,
Procedure involved abrading skin to achieve a scalp-electrode impedance < 5 kilo Ohms.
Abrasion removes surface epidermal layer that has greater impedance than underlying tissue.
68
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69
http://www.sengpielaudio.com/calculator-ohmslaw.htm
Impedance
Friday, January 14, 2011
Impedance
Voltage (V) = Current(I) X Resistance(R)
If Resistance increases, Current flow will decrease: V/R = IIf Voltage increases, Current flow increases: V = C x R
Current measured in AmpsVoltage measured in VoltsResistance measured in Ohms
Plumbing Analogy:Voltage ~ Water pressure (in a tank)Current ~ Flow Rate (from the tank)Resistance ~ pipe size (allowing water to escape from tank)
Friday, January 14, 2011
71
Impedance
Friday, January 14, 2011
High vs. Low Impedance Amplifiers
72
Impedance
Friday, January 14, 2011
High vs. Low Impedance Amplifiers (elec) vs. (amp) High vs. High: 5x10-10
.00000000005 Low vs. Low: 5x10-9
.0000000005
73
Practice electric circuits:http://www.phy.hk/wiki/englishhtm/Circuit.htm
Impedance
Friday, January 14, 2011
Ferree, T., Luu, P., Russel, J. S., & Tucker, D. M. (2001). Scalp electrode impedance, infection risk, and EEG data quality. Clinical Neurophysiology, 112, 536-544.
Impedance
Note: Watts = Amps x Volts
Friday, January 14, 2011
Electrode Paste vs. Collodian
Adhesive paste EC2 vs. collodion for long-term scalp electrodes placement 40 patients
20: electrode placement on scalp with collodion - Group C(ollodian)
20: EC2 used - Group P(aste). impedance of electrodes measured after electrode
placement (T1) and after 24 h of recording (T2), Application time calculated for all patients
RESULTS: At each observation, group C showed mean values of electrode impedance significantly higher than group P
Collodion: T1: 16.8 kohm; T2: 6.5 kohm EC2 Paste: T1: 2.4 kohm; T2: 4.0 kohm, p < 1 x 10(-5).
75
Friday, January 14, 2011
Time required to make montage and provide daily maintenance was significantly shorter in group P than in group C
Collodion: 44.3 and 19.7 min EC2 Paste: 20.8 and 10.5 min, p < 1 x 10(-5).
CONCLUSIONS: EC2 paste attaches scalp electrode in less time,
with better recording quality as a result of lower electrode impedance values, than collodion.
SIGNIFICANCE: EC2 paste can substitute for collodion in electrode placement for long-term video-EEG monitoring, with an optimal cost-benefit ratio in terms of recording performance, time consumption, & safety.
76
Electrode Paste vs. Collodian
Friday, January 14, 2011
77
QUESTIONS ???
Friday, January 14, 2011
Filters
Friday, January 14, 2011
Filters
ERPs (and EEG) are electrical signals that vary in their frequencies and amplitude.
Friday, January 14, 2011
Filters
ERPs (and EEG) are electrical signals that vary in their frequencies and amplitude.
Filter determines the way in which amplifier sensitivity changes as frequency is reduced.
Friday, January 14, 2011
Filters
ERPs (and EEG) are electrical signals that vary in their frequencies and amplitude.
Filter determines the way in which amplifier sensitivity changes as frequency is reduced.
Frequency response - bandwidth of amplifier determined by its high & low frequency filters.
Friday, January 14, 2011
Filters
Friday, January 14, 2011
D.C. Amplifier
Filters
Friday, January 14, 2011
D.C. Amplifier Sensitivity does not change with
decreasing frequency.
Filters
Friday, January 14, 2011
D.C. Amplifier Sensitivity does not change with
decreasing frequency.
Filters
Friday, January 14, 2011
D.C. Amplifier Sensitivity does not change with
decreasing frequency.
Subject to very slow change of output level (drift).
Filters
Friday, January 14, 2011
Filters
Friday, January 14, 2011
Low Pass Filter - attenuates HIGH frequency while “saving” or passing through the LOW frequencies (high frequency filter, high band pass filter)
Filters
Friday, January 14, 2011
Low Pass Filter - attenuates HIGH frequency while “saving” or passing through the LOW frequencies (high frequency filter, high band pass filter)
Filters
Friday, January 14, 2011
Low Pass Filter - attenuates HIGH frequency while “saving” or passing through the LOW frequencies (high frequency filter, high band pass filter)
High Pass Filter - attenuates LOW frequency while “saving” or passing through the HIGH frequencies (low frequency filter, low band pass filter)
Filters
Friday, January 14, 2011
Amplifier Filter Settings
Friday, January 14, 2011
Amplifier Filter Settings Signals are reduced 50% already
when frequency reaches setting depicted on most amplifiers.
Friday, January 14, 2011
Amplifier Filter Settings Signals are reduced 50% already
when frequency reaches setting depicted on most amplifiers.
Referred to as “Half-Amplitudes”
Friday, January 14, 2011
Amplifier Filter Settings Signals are reduced 50% already
when frequency reaches setting depicted on most amplifiers.
Referred to as “Half-Amplitudes” E.G., Setting on an amplifier of 2Hz
and 30Hz means signal already reduced by 50% at filter boundaries.
Friday, January 14, 2011
Filters
Friday, January 14, 2011
Filtering - sometimes represented as a Time Constant (TC)
Filters
Friday, January 14, 2011
Filtering - sometimes represented as a Time Constant (TC)
Filters
Friday, January 14, 2011
Filtering - sometimes represented as a Time Constant (TC)
Describes how amplifier responds to a voltage change
Filters
Friday, January 14, 2011
Filters
Friday, January 14, 2011
Voltage -> amplifier is changed.
Filters
Friday, January 14, 2011
Voltage -> amplifier is changed. Amplifier output changed but gradually
returns to baseline, producing a curve (exponential curve) that approaches its final value at a decreasing rate.
Filters
Friday, January 14, 2011
Voltage -> amplifier is changed. Amplifier output changed but gradually
returns to baseline, producing a curve (exponential curve) that approaches its final value at a decreasing rate.
This curve has time constant (the time it takes for the AMPLITUDE to FALL to 37% of its INITIAL VALUE).
Filters
Friday, January 14, 2011
As TIME CONSTANT (TC) increases, high pass filter frequency decreases (memorize ***)
Filters
Friday, January 14, 2011
TIME CONSTANT = C Frequency = f Pi = 3.1415
1/(2 x Pi x C) = f 0.159/C = f 0.159/0.3 = 0.5 Hz (cut off point of low-
frequency.)
TC = 0.1, low frequency passed = 1.59 Hz TC = 0.5, low frequency passed = 0.318 Hz TC = 1.0, low frequency passed = 0.159 Hz
Filters
Friday, January 14, 2011
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Filters: ERP amplitude and latency WILL change when applying different filters.
Friday, January 14, 2011
Filters: ERP amplitude and latency WILL change when applying different filters.
High Pass Filter Low Pass Filter
NOTE: Filters do NOT cut off the signal at filter settings !Friday, January 14, 2011
Filters .3 - 100 Hz
Friday, January 14, 2011
Filters - .3 - 30 Hz (60 Hz notch filter)
Friday, January 14, 2011
Filters - .3 - 30 Hz
Friday, January 14, 2011
Note: 60 Hz filter has no effect on ERP waveform if LOW PASS = 30 Hz
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92
As LOW PASS filter setting DECREASES, Peak Latencies will INCREASE (occur later) and slower frequencies will become more prominent in the ERP waveform as higher frequencies are filtered out (excluded).
Filters
aka: Peak Latencies will occur later in the ERP waveform.
Friday, January 14, 2011
Filters .3 - 100 Hz
Friday, January 14, 2011
Filters - .3 - 30 Hz
Friday, January 14, 2011
Filters - 0.3 - 10 Hz
Friday, January 14, 2011
Filters - .3 - 5.0 Hz
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97
As LOW PASS filter setting INCREASES, Peak Latencies will DECREASE and higher (faster) frequencies will become more prominent in the ERP waveform as higher frequencies are included (not filtered out).
Filters
aka: Peak Latencies will occur EARLIER in the ERP waveform.
Friday, January 14, 2011
Filters - 2.0 - 10 Hz
Friday, January 14, 2011
Filters - 2.0 - 20 Hz
Lower Low Pass gives Longer Latencies !!!Friday, January 14, 2011
Filters - 2.0 - 30 Hz
Friday, January 14, 2011
Filters - 2.0 - 100 Hz (60 Hz notch filter)
Friday, January 14, 2011
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As HIGH PASS filter setting INCREASES, Peak Latencies will DECREASE and higher (faster) frequencies will become more prominent in the ERP waveform as lower frequencies are excluded (filtered out).
Amplitudes will appear to decrease (get smaller).
Filters
aka: Peak Latencies will occur EARLIER in the ERP waveform.aka: Peak Amplitudes will decrease in size.
Friday, January 14, 2011
Filters - 2.0 - 100 Hz (60 Hz notch filter)
Friday, January 14, 2011
Filters - 3.0 - 100 Hz (60 Hz notch filter)
Friday, January 14, 2011
Filters - 5.0 - 100 Hz (60 Hz notch filter)
Friday, January 14, 2011
Filters - signals change with filtering
Friday, January 14, 2011
Filters: Topography 2.0 - 100 Hz (60hz)
Friday, January 14, 2011
Filters: Topography .3 - 100 Hz
Friday, January 14, 2011
Filters: Topography .3 - 30 Hz
Friday, January 14, 2011
Filters: Topography .3 - 10 Hz
Friday, January 14, 2011
Filters: Topography .3 - 5 Hz
Friday, January 14, 2011
Filters: Topography 5.0 - 10 Hz
Friday, January 14, 2011
Filters: Topography 5.0 - 15 Hz
Friday, January 14, 2011
Filters: Topography 5.0 - 100 Hz (60hz)
Friday, January 14, 2011
Filters: Topography 10 - 100 Hz (60hz)
Friday, January 14, 2011
Filters: Topography 10 - 30 Hz
Friday, January 14, 2011
Take Home Memory
Different Filters produce different ERP waveforms Latency shifts Amplitude variations (positive & negative peaks) Slope changes Component structure impacted
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When reading the literature ALWAYS pay strict attention to filter settings and gain settings used by investigators.
DIFFERENT RESULTS with DIFFERENT FILTERS and GAIN (amplitude) settings.
118
CRITICAL
Friday, January 14, 2011
QUESTION
If 2 ERPs are collected but with different filter settings, which is the REAL data?
Will the REAL ERP please stand up!
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120
QUESTIONS ???
Friday, January 14, 2011
Adult Peak Components
ERPs usually described in terms of Peaks (positive or negative) Latency (post stimulus onset) Duration (e.g., slow wave) Scalp topography (maximal peak
location) Source (location within the brain)
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Scalp Volume Conduction
Current flow across the scalp Produces latency shifts from one part of
scalp to another Also produces amplitude shifts across
scalp Signals sum across the scalp
large positive wave on scalp meeting large negative wave could sum to flat line!
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EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300)
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400)
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400) Mismatch negativity (MMN)
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400) Mismatch negativity (MMN) Error-related negativity (ERN)
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400) Mismatch negativity (MMN) Error-related negativity (ERN) Feedback-Related Negativity (FRN)
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400) Mismatch negativity (MMN) Error-related negativity (ERN) Feedback-Related Negativity (FRN) Habituation
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400) Mismatch negativity (MMN) Error-related negativity (ERN) Feedback-Related Negativity (FRN) Habituation Contingent Negative Variation (CNV)
Friday, January 14, 2011
EXPERIMENTAL DESIGN ISSUES:Types of Experiments
Common approaches Odd-ball tasks (P3 or P300) Sentence completion (N400) Mismatch negativity (MMN) Error-related negativity (ERN) Feedback-Related Negativity (FRN) Habituation Contingent Negative Variation (CNV) Random order of presentation
Friday, January 14, 2011
Adult Peak Components: Some Descriptions
P1 or P50 (auditory)
Friday, January 14, 2011
Adult Peak Components: Some Descriptions
P1 or P50 (auditory)- Not always present
- Occurs earlier over posterior than anterior scalp electrode sites
- Larger amplitudes over frontal and/or central regions
Friday, January 14, 2011
P1 or P50 (auditory)- Distribution symmetrical over both hemispheres except for anterior temporal regions where larger amplitudes occur over left hemisphere;
-Overall, peak amplitude and latency decrease with age to the point where the peak disappears (Coch, et al., 2002).
Adult Peak Components
Friday, January 14, 2011
P1 or P50 (auditory)- Frequently associated with auditory inhibition in sensory gating paradigm where paired clicks presented at short ISIs.
Amplitude of averaged ERP to second of paired clicks is typically reduced compared to averaged response to the first click.
Magnitude of suppression commonly interpreted as neurophysiological index of sensory gating.
Adult Peak Components
Friday, January 14, 2011
P1 or P50 (auditory)
- Reduced suppression frequently reported for schizophrenic patients.
- In some neuropsychiatric disorders (schizophrenia, mania), peak amplitude to paired stimuli approximately equal.
- P1 latency clinically used to diagnose neurodegenerative diseases (multiple sclerosis, Parkinson’s Disease).
Adult Peak Components
Friday, January 14, 2011
P1 or P50 (auditory)
- Buchwald et al. (1992) proposed that P50 response associated with ascending reticular activating system (RAS) and its post-synaptic thalamic targets.
- Thoma et al. (2003) and Huotilainen (1998) independently localized sources of P50 in superior temporal gyrus using MEG approach.
-Weisser et al (2001) co-registered auditory evoked potentials & magnetic fields (AEFs). The resulting equivalent dipole model for ERPs consisted of one source in auditory cortex of each hemisphere and a radially oriented medial frontal source.
Adult Peak Components
Friday, January 14, 2011
P1 or P50 (visual)
- Visual P1 differs from auditory P1 in terms of evoking stimulus, neurocognitive and neurophysiological mechanism, peak latency, scalp distribution, neural sources.
- Visual P1 typically recorded in a checkerboard-reversal task or similar light-flashes paradigms but can also be present for other visual stimuli (e.g., faces) & is largest over the occipital regions.
- Negative peak may be present at same latency over frontal, central areas.
Adult Peak Components
Friday, January 14, 2011
P1 or P50 (visual)
- P1 amplitude generally varies with amount of attention in Posner’s attention cueing paradigm & in spatial selective attention experiments.
- P1 reflects suppression of noise because amplitude decreased for unattended locations but did not increase for attended stimuli.
- P1 amplitude also increased when speed of response was emphasized, suggesting that P1 may also reflect level of arousal.
Adult Peak Components
Friday, January 14, 2011
P1 or P50 (visual)
- Sources identified using PET, BESA, and LORETA methods in ventral and lateral occipital regions (Clark, et al., 1996; Gomez, et al., 1994).
- Suggests striate (Strik, et al., 1998) or extrastriate (posterior fusiform gyrus) origin (Heinze, et al., 1994).
- Rossion, et al. (1999) in a face identification paradigm reported similar sources and sources in posterior-parietal regions, suggesting additional involvement of dorsal and ventral neural components.
Adult Peak Components
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N1 (N100)
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N1 (N100)
N1 typically occurs approximately 100 ms after stimulus onset.
One of easiest components to identify regardless of specific analysis approach.
Good convergence in findings based on analyses of PCA factor scores (Beauducel, et al., 2000), baseline to peak amplitude (Pekkonen, et al., 1995; Sandman & Patterson, 2000), and baseline to peak latency (Segalowitz & Barnes, 1993).
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N1 assumed to reflect selective attention to basic stimulus characteristics, initial selection for later pattern recognition, & intentional discrimination processing.
Peak latency & amplitude depend on stimulus modality. Auditory stimuli elicit a larger N1 with shorter latency than visual stimuli (Hugdahl, 1995).
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N1 (N100)
Friday, January 14, 2011
N1 or N100 (Auditory) Maximum amplitude over frontocentral areas (Vaughn &
Ritter, 1970) or vertex (Picton, et al., 1974).
Some studies differentiate into 3 different components with maximum amplitudes over temporal areas (latency 75 ms and 130 ms) & over vertex (latency 100 ms; McCallum & Curry, ‘80; Giard, et al., ‘94).
Naatanen and Picton (1987) reviewed the 3 components of N1. Proposed that early temporal and vertex components reflect sensory and physical properties of the stimuli (e.g., intensity, location, timing in regards to other stimuli) while later temporal component are less specific and reflect transient arousal.
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NOTE, majority of studies treat N1 as single component occurring 100 ms after stimulus onset with maximum amplitude at the vertex electrode.
N1 amplitude enhanced by increased attention to stimuli (Hillyard et al, 1973;
Knight, et al., 1981; Ritter, et al., 1988; Mangun, 1995) increasing inter-stimulus interval (Hari, et al., 1982).
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N1 or N100 (Auditory)
Friday, January 14, 2011
N1 most likely generated by sources in primary auditory cortex in the temporal lobe (Vaughn & Ritter, 1970).
MEG, BESA, and lesions studies consistently localize auditory N1 in superior temporal plane (e.g., Papanicolaou, et al., 1990; Scherg, et al., 1989; Knight, et al., 1988).
However, several studies proposed additional sources in frontal lobe that could be activated from temporal lobe (e.g., Giard, et al., 1994).
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N1 or N100 (Auditory)
Friday, January 14, 2011
Usually largest (maximum) over occipital region (Hopf, et al., 2002) or inferior temporal regions (Bokura, et al., 2001).
Amplitude larger in discrimination tasks, but smaller if short ISIs. [** could disappear]
N1 discrimination effect attributed to enhanced processing of attended location (Luck, 1995), not due to arousal because amplitudes are larger in tasks placing no emphasis on the speed of response .
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N1 or N100 (VISUAL)
Friday, January 14, 2011
Not affected by inhibition (no Go/No-Go response differences).
Like auditory N1, visual N1 occurs at 100 ms over central midline sites & 165 ms over posterior sites.
Anterior N1 = response preparation because eliminated if no motor response required.
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N1 or N100 (VISUAL)
Friday, January 14, 2011
Located visual N1 sources in inferior occipital lobe and occipito-temporal junction using a combination of techniques (MEG, ERP, and MRI), Hopf et al. (2002).
However, Bokura et al., (2001) using the LORETA approach, identified additional sources of the visual N1 in the inferior temporal lobe.
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N1 or N100 (VISUAL)
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QUESTIONS ???
Friday, January 14, 2011
P2
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Friday, January 14, 2011
P2
Like N1 and P1, long considered “obligatory cortical potential” since it has low inter-individual variability and high replicability
Identified in many different cognitive tasks including selective attention, stimulus change, feature detection processes, and short-term memory.
P2 sensitive to stimulus physical parameters such as loudness.
Participant differences such as reading ability also change P2 amplitude to auditory stimuli.
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P2 (Auditory)
P2 often occurs together with N1, yet peaks can be dissociated.
P2 scalp distribution less localized than N1 & has its highest amplitude over central region.
Temporal peak of P2 can occur over a broader latency range than the preceding peaks, ranging from 150 - 275 ms.
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P2 can be double-peaked.
Similar to N1, P2 has been consistently identified by analysis procedures:
PCA factor scores (Beauducel, et al., 2000)
Baseline to peak amplitude (Beauducel, et al., 2000; Sandman, & Patterson, 2000)
Baseline to peak latency (Segalowitz & Barnes, 1993)
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P2 (Auditory)
Friday, January 14, 2011
Generators for auditory P2 thought centered mainly in primary & secondary auditory cortices.
Both auditory N1 and P2 often represented by 2 dipoles: one in primary auditory cortex and one in secondary auditory cortex.
Using BESA and LORETA to identify dipole locations for the N1/P2 component, Mulert et al. (2002) identified one in superior temporal region with a tangential orientation while second was located in temporal lobe with a radial orientation. These dipoles reflected primary and secondary cortices, respectively.
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P2 (Auditory)
Friday, January 14, 2011
P2 amplitude increases with complexity of the stimuli.
Topographic distribution of visually elicited P2 is characterized by a positive shift at the frontal sites around 150-200 ms after stimulus onset and a large negativity, approximately 200 ms following stimulus onset at the occipital sites
Using BESA dipole analysis, Talsma and Kok (2001) reported a symmetrical dipole pair localized in the inferior occipital (extrastriate) areas. Findings suggest that both topographic distribution and dipole position varied slightly when attending vs. not attending to visual images.
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P2 (VISUAL)
Friday, January 14, 2011
149
QUESTIONS ???
Friday, January 14, 2011
N2
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N2
Influenced by features of the experiment, such as modality and stimuli presentation parameters.
Shares some of its functional interpretation with mismatch negativity (MMN) because both indicate a detection of a deviation between a particular stimulus and the subject’s expectation.
However, unlike the MMN, the subject MUST pay attention to the stimuli.
Ken Squires, et al. (1975) first reported this component. Ss viewed 2 stimuli. When the following image did NOT MATCH what was expected, a larger N2 occurred over frontal regions.
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N2 has multiple psychological interpretations including:
orienting response (Loveless, 1983), stimulus discrimination (Satterfield, et al., 1990), target selection (Donchin, et al., 1978), reflecting task demands (Johnson, 1989; Duncan, et al.,
1994).
N2 has more inter-individual variation (Michalewski, et al., 1986; Pekkonen, et al. 1995).
N2 is smaller in amplitude & shorter in latency for shorter ISIs (Polich & Bondurant, 1997).
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N2
Friday, January 14, 2011
N2 topographic distribution depends on sensory stimulus modality:
Auditory elicit largest N2 amplitude at vertex. Scalp current density analysis indicate bilateral sources in supratemporal auditory cortex.
Visual elicited highest N2 amplitude over preoccipital region.
N2 to visual stimuli varied based on the stimuli type, such as written words, pictures of objects, or human faces.
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N2 Topography
Friday, January 14, 2011
Using intracranial electrodes placed directly on cortex, letter-strings of recognizable nouns produced N2 component at 4th occipital gyrus near occipitotemporal sulci. Pictures of complex objects, (cars, butterflies) resulted in N2 response over inferior lingual gyrus medially & middle occipital gyrus laterally. Effect not present for scrambled pictures.
Face recognition tasks elicit N2 over fusiform gyrus & inferior temporal or occipital gyri just lateral to the occipito-temporal or inferior occipital sulci (see N170).
Such differing distributions indicate N2 may reflect category-specific processing (Allison, et al., 1999).
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N2 Sources
Friday, January 14, 2011
N2 and Inhibition
N2 associated with Go/No-Go paradigm, in which subject responds to some stimuli (Go trials), but inhibits response to another class of stimuli (No-Go trials).
ERPs on No-Go trials are characterized by a large negative peak relative to the Go trials between 100 and 300 ms after stimulus onset (response inhibition ??).
N2 occurred both in relation to overt & covert responses, indicating that N2 Go/ No-Go effect not due only to motor responses. Instead, N2 present whenever responses must be interrupted.
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Amplitude and polarity of N2 inhibition response changes depending on the complexity of the task.
In some instances, the Go/No-Go response has been reported as a positive peak, suggesting this pattern was due to large amplitude of the P300 in difficult tasks.
N2 was larger when subjects have less time to respond.
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N2 and Inhibition
Friday, January 14, 2011
N2 for the visual & auditory task is especially strong over fronto-central electrodes when the Go response is withheld.
Scalp distribution differs from Error Related Negativity (ERN) that occurs approximately 125 ms after an incorrect response.
N2 response engages different processes than the error monitoring processes reflected in the ERN.
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N2 and Inhibition
Friday, January 14, 2011
Mathalon et al. (2003) using ERP and fMRI identified activation of caudal and motor anterior cingulate cortices during both correctly and incorrectly inhibited responses.
These sources differed from ERN responses that were related to caudal and rostral anterior cingulate cortices.
Reinforces view the N2 reflects inhibitory responses distinct from error-related negativity.
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N2 and Inhibition
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QUESTIONS ???
Friday, January 14, 2011
Mismatch Negativity (MMN).
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Mismatch Negativity (MMN). Naatanen et al. (1978) first described MMN wave as a
negative deflection, latency = 100 - 250 ms.
Amplitude largest frontal & central electrode sites.
MMN is elicited using an “oddball paradigm” where an occasional deviant stimulus is presented in a stream of more frequent standard stimuli.
Test-retest reliability.
Because MMN paradigms require no attention to the stimuli, widely used in developmental research.
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Calculating the MMN
Traditional: Subtract the averaged waveform of all standard stimuli FROM the averaged waveform of all deviant stimuli collected during the same test session.
Alternative (2004): Present uninterrupted string of standard stimuli midway through experimental session to provide a alternative baseline for calculating the MMN.
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Kraus, McGee, Carrell, Zecker, Nicol, & Koch, 1996
Friday, January 14, 2011
Mismatch Negativity (MMN)
MMN evoked by any perceivable physical deviance from the standard stimulus (e.g., changes in tone duration, frequency, intensity, and ISI).
Numerous theories ”Memory trace" - MMN elicited in response to violations of simple rules
governing properties of information - violation of an automatically formed, short-term neural model or memory trace of physical or abstract environmental regularities
Population of sensory afferent neuronal elements that respond to sound, and; ii) a separate population of memory neuronal elements that build a neural model of standard stimulation and respond more vigorously when the incoming stimulation violates that neural model
"Fresh afferent" - sensory afferent neuronal elements that are tuned to properties of the standard stimulation respond less vigorously upon repeated stimulation. Thus when a deviant activates a distinct new population of neuronal elements that is tuned to the different properties of the deviant rather than the standard, these fresh afferents respond more vigorously.
Sensory afferents are memory neurons.164
Friday, January 14, 2011
Mismatch Negativity (MMN) Auditory MMN often used to test ability of subject to
discriminate linguistic stimuli (e.g., speech sounds with different voice onset time or place of articulation.
Data analyzed by subtracting average ERP elicited by standard stimuli from average ERPs for the deviants.
This subtracted component generally displays an onset latency as short as 50 ms and a peak latency = 100 - 200 ms (Naatanen, 1992).
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Mismatch Negativity (MMN) Sources for auditory stimuli
MEG: significant differences between dipoles produced by deviants differing in intensity, frequency and duration (Rosburg, 2003).
Dipoles for frequency and duration deviants located significantly inferior in comparison to the source of intensity deviants and differed significantly from each other in the anterior-posterior direction.
All dipoles located within temporal lobes. Leibenthal et al. (2003) recorded fMRI and ERP data
simultaneously to an MMN task. Main areas of increased BOLD signal in right superior
temporal gyrus & right superior temporal plane.
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Mismatch Negativity (MMN) Features influencing MMN Negative wave usually associated with
MMN.
Reports of positive wave around 200 ms corresponding to the MMN response (Leppanen, et al., 2002).
The reason for this difference may be due to differences in filter settings. **
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Mismatch Negativity (MMN) Features influencing MMN
Some reports indicate substantially reduced MMN response in subjects not attending to the stimuli
Probability deviant stimuli influences effect.
Must maintain balance between presenting enough deviant trials to obtain low-noise average responses, and not allowing the subject to habituate to the deviant, thus diminishing effect.
Size of MMN response decreased (non linear), Time for habituation varies as function of
stimulus complexity. 168
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Mismatch Negativity (MMN) Visual
169
MMN is found for visual stimuli (Tales, Newton, Troscianko & Butler, 1999).
Source Localization techniques suggest involvement of primary visual cortex and adjacent areas (Gratton, 1997; Gratton, et al. 1998).
Friday, January 14, 2011
N170 Face Processing
170
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N170 N170 ranges between 156 & 189 ms.
Associated with visual processing of human faces.
Topographic distribution for both familiar & unfamiliar faces largest over occipito-temporal regions.
Amplitude significantly larger when viewing faces than other natural or human-made objects.
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N170 Prosopagnosia Patients do not show an N170
response to faces.
N170 not specific to human faces but expert object recognition (Tanaka & Curran, 2001)
Intracranial recordings of EP & fMRI point to fusiform gyrus as neuroanatomical substrate of N170. BUT source localization of N170 using BESA identified source in lateral occipitotemporal region outside fusiform gyrus.
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173
QUESTIONS ???
Friday, January 14, 2011
P300 - Two Components P300a component associated with
the automatic 'Orienting Reflex'
P300b component associated with controlled processing (most studied)
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P300 Odd-ball tasks
S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.
Friday, January 14, 2011
P300 Odd-ball tasks P300 amplitude increases to
infrequent stimulus
S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.
Friday, January 14, 2011
P300 Odd-ball tasks P300 amplitude increases to
infrequent stimulus Frequent 80% of trials, infrequent 20%
S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.
Friday, January 14, 2011
P300 Odd-ball tasks P300 amplitude increases to
infrequent stimulus Frequent 80% of trials, infrequent 20% Requires attention & response to
infrequent stimulus
S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.
Friday, January 14, 2011
P300 Odd-ball tasks P300 amplitude increases to
infrequent stimulus Frequent 80% of trials, infrequent 20% Requires attention & response to
infrequent stimulus Controls important
S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.
Friday, January 14, 2011
P300 Odd-ball tasks P300 amplitude increases to
infrequent stimulus Frequent 80% of trials, infrequent 20% Requires attention & response to
infrequent stimulus Controls important
ERP averages based on same # trials for both frequent and infrequent stimuli
S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.
Friday, January 14, 2011
P3a
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P3a P3a, frontal maximum scalp distribution. Slightly
shorter latency for visual vs. auditory and somatosensory stimuli.
Frontal P3a occurs when subject not required to actively respond to the targets (N. Squires, et al., 1975) or when novel stimulus is added to the standard 2-stimulus oddball paradigm.
Frontal P3a assumed to reflect involuntary attention as well as inhibition. In Go/No-Go paradigms, P3a larger in amplitude in No-Go than Go conditions (maximal at parietal sites for Go).
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P3a Neural substrate in medial parietal lobe
(early: 317 ms) and in the left superior prefrontal cortex (late: 651 ms) for Go trials;
Sources for No-Go trials (365 ms) originate in left lateral orbitofrontal cortex.
P3a reduced by lesions to frontal cortex (Knight, 1991).
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P3b or “P300”
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P3b or P300 Most extensively researched ERP component. Sutton et al., 1965: pronounced positivity occurring in
response to unexpected stimulus approximately 300 ms after stimulus onset.
Oddball most typical paradigm for eliciting P3b component, - a target stimulus presented infrequently among more common distracter stimuli.
To get P3, subject must pay attention and respond to stimuli (unlike MMN) and the ratio of target to distracter stimuli must be low (fewer targets -> larger peak).
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P3b or P300 AMPLITUDE affected by attention, stimulus
probability, stimulus relevance, amount of processing resources available (e.g., single vs. dual tasks, quality of selection, and attention allocation.
Interstimulus interval length affects AMPLITUDE independently of stimulus probability with shorter intervals resulting in larger P3b or P300.
LATENCY varies with stimulus complexity, effectiveness of selection, and sustained attention.
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P3b or P300 Visual P3 has larger & longer latency than auditory P3.
P3 largest over parietal & midline regions.
Auditory stimuli elicited shorter latency P3 over parietal regions, and longer latency over central sites.
Functional interpretation of classic P3b diverse – indicator of memory updating (Donchin & Coles, 1988) reflects a combination of processes that vary by task and
situation, including more elaborate active stimulus discrimination and responses preparation.
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P3b or P300 P3 latency assumed to reflect the duration of stimulus
evaluation.
P3 component attracted attention in clinical studies. Because P3 amplitude varies with the amount of attention paid to stimuli, this component widely studied in populations with attention deficits (e.g., ADHD) - interpreted to reflect information regarding various attentional functions.
P3 latency reported related to cognitive abilities with shorter latencies associated with better performance
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P3b or P300 Sources of P3 not clearly identified but some expected to be
in medial temporal lobe, including hippocampal region related to memory (Donchin, 1981; Paller, McCarthy, et al, 1992), parahippocampal gyrus, amygdala, or thalamus (Katayama, et al., 1985).
Lesion data suggest multiple generators, including temporo-parietal junction (Knight et al, 1989). Tarkka et al., (1995) investigated possible sources and reported that combining different locations produced better model.
MEG analyses located sources in floor of Sylvian fissure (superior temporal gyrus) and deeper sources in thalamus-hippocampus.
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185
QUESTIONS ???
Friday, January 14, 2011
N400
186
“He spread the warm butter with socks.”
Friday, January 14, 2011
N400 Sentence Completion
Friday, January 14, 2011
N400 Sentence Completion N400 larger for unexpected, low
probability endings.
Friday, January 14, 2011
N400 Sentence Completion N400 larger for unexpected, low
probability endings. Fixed intervals between words
Friday, January 14, 2011
N400 Sentence Completion N400 larger for unexpected, low
probability endings. Fixed intervals between words Words presented one at a time
Friday, January 14, 2011
N400 Sentence Completion N400 larger for unexpected, low
probability endings. Fixed intervals between words Words presented one at a time Usual interval 1 S.
Friday, January 14, 2011
N400 Negative component approximately 400 ms after
stimulus onset.
Usually associated with semantic comprehension in both visual and auditory sentence comprehension tasks.
First identified by Kutas and Hillyard (1979).
Elicited by anomalies in American Sign Language.
N400 did not occur when participants presented with anomalies in music (Besson, et al., 1994).
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Kutas & Hillyard, 1980
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N400 study with children The train runs on a track (CC) The train runs on a crack (CI) Child presses either red or green key to
indicate if the sentence “sounds ok or funny”.
36 sentences for each condition. All sentences 6 words in length. Total data points digitized = 300
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N400
ms 0 250 500 700
Wordn=68
IncorrectCorrect
12 year olds
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N400 Paradigm Words of a sentence were visually presented one after
another at fixed intervals in a serial manner.
Last word of the sentence either congruous (“He took a sip from the water fountain”) or incongruous but syntactically appropriate (“He took a sip from the transmitter”) with rest of the sentence.
Incongruous words elicited larger amplitude N400 response than congruous words for both auditory and visual stimuli.
N400 amplitude correlated with degree of incongruency of final word to sentence (e.g., “ transmitter”)
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N400 Kutas and Hillyard (1983): N400 effect only held true
for semantic, but not syntactic deviations.
Supposedly listeners use information from the wider discourse when interpreting appropriateness of particular word (van Berkum, et al., 2003).
N400 also elicited in semantic word pairs (Rugg, 1985), semantic priming tasks (Bentin, et al., 1985; Ruz, et al., 2003) and matching semantic material to visual displays (Huddy, et al., 2003).
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N400 (Modalities) For both visual and auditory displays, the N400 is larger
for anomalous endings than expected endings over the parietal and temporal regions of the right hemisphere.
But there are modality effects: N400 is earlier in the visual (475 ms.) than auditory
(525 ms) modality but only over the temporal, anterior temporal and frontal sites (Holcomb, et al., 1992).
Earliest peak in the visual modality is over parietal & temporal sites, while in the auditory modality it is over parietal & occipital sites (Holcomb, et al., 1992).
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N400 (Asymmetries) Activation in left hemisphere occurrs earlier than
activation in the right) in ONLY visual modality (Holcomb, et al., 1992).
N400 not specific to written words, because spoken words (McCallum, et al., 1984; Holcomb, et al., 1992; Connolly & Phillips, 1994) & pictures (Nigam, et al., 1992) elicit N400.
N400 response also elicited by incongruent solutions to mathematical multiplication problems (Niedeggen, et al., 1999).
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N400 & Attention Still Unclear:
Amount of attention necessary to produce N400,
Cognitive processes involved (Osterhout & Holcomb, 1995).
Holcomb (1988) reported N400 more robust when attention required but occurs when participants not attending to stimuli.
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N400 & Attention However, Bentin et al. (1995) reported (dichotic
listening task) that N400 was absent for material presented in unattended ear.
Amount of effortful semantic processing required is unclear. Kutas and Hillyard (1993) reported N400 effect even in tasks not requiring semantic processing although Chwilla et al. (1995) found no N400 when attention not directed to meaning of stimuli.
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N400 & Sources Likely multiple generators that are functionally (Nobre
& McCarthy, 1994) and spatially (Halgren, et al., 1994; McCarthy, et al., 1995) segregated.
Recent work points to parahippocampal anterior fusiform gyrus as generator (McCarthy et al, 1995).
MEG studies pinpoint lateral temporal region as origin of N400 response (Simos, et al., 1997).
Intracortical depth recordings using written words point to medial temporal structures near hippocampus & amygdala (Halgren, et al., 1994).
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Late Positive Component (LPC)
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Late Positive Component (LPC)
Positive-going ERP component.Studies of explicit recognition memory.Largest over parietal scalp sites (mastoid reference).Begins approximately 400-500 ms after stimulus onset.Duration = 200 ms ERP "old/new" effect.
200
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Late Positive Component (LPC)
S given list to learn.ERPs recorded to new list including old and new words.S to indicate old vs. new words.Typical larger LPC to old vs new words.
Also done as continuous test - each trial S indicates if old vs. new item.
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Late Positive Component (LPC)
ERP & fMRI indicate lateral parietal cortex, perhaps with medial temporal lobe and hippocampus.
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QUESTIONS ???
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ERNError Related Negativity
ERN reflects activity of a brain system that detects & corrects for errors.
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ERN Paradigm Two ways to generate an ERN response:
following an incorrect response during feedback of incorrect choice
Hajcak, Holroyd, Moser, Simons, 2005; Holroyd, & Coles, 2002; Holroyd, Nieuwenhuis, Yeung, Cohen, 2003
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ERN
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ERN Paradigm During speeded
response timing tasks, an incorrect response produces a negative peak ~ 100 ms
Gehring, Goss, Coles, Meyer & Donchin, 1993
For reinforcement tasks, negativity around 250 ms indicates performance was incorrect
Miltner, Baun & Coles, 1997
Negativity changes in amplitude for incorrect responses in high reward conditions or correct responses in low reward condition
Holroyd, Nieuwenhuis, Yeung, & Cohen, 2003
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ANALYSIS-Feedback Amplitude for ERN measured from
baseline to peak between 160 ms to 240 ms following feedback
Holroyd, Nieuwenhuis, Yeung & Cohen, 2003
Holroyd et al., (2003) used algorithm to identify amplitude of the greatest negativity in the peak starting at the slope of the first negativity through 325 ms
Latency measures start at the maximum component amplitude
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ANALYSIS - Incorrect Response Amplitude measured early: 50 - 110 post
incorrect response Luu et al., 200
Usually look at incongruent trials (i.e. Flanker task/go-no go task)
Generate individual waveforms for error trials **Some groups used smoothing techniques with a
nonphase-shifting single pass 17-point moving average (34 ms, approximately 3 db down at 15 Hz) --Santesso, Segalowitz & Schmidt, 2005
Filters set around 20 Hz offline Holroyd and Colleagues
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ERN and Personality High Negative affect
(high neuroticism) results in larger amplitude on initial tasks
Tucker et al., 1999
ERN reflects certainty of loss (greater realization=greater ERN)
Investment in task changes ERN
Holroyd and Coles, 2002; Scheffers and Coles, 2000
10-year old children ranked on Junior Eysenck Personality Questionnaire show different ERN
High psychoticism and low lie scores result in smaller ERN
Similar to adults: see Dikman and Allen (2000)
ERN affected by personality and concern of task performance
Santesso, Segalowitz, & Schmidt,(2005)
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Source
Within the anterior cingulate cortex (ACC), mesencephalic dopamine neurons synapse on motor neurons and cause behavior to occur (e.g. pushing correct button)
Basal ganglia mediated by feedback and stimulus input impact ERN generated by the electrical charge of neurons synapsing on the ACC. When events are worse than expected, decrease in
dopamine activity disinhibits dendrites in ACC, resulting in a negative waveform, ERN
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Source
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The Anterior Cingulate Cortex
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Feedback-Related Negativity
• A negative deflection in the waveform approximately 250-350 ms after the participant given negative feedback (Miltner, Braun, & Coles, 1997)
• Thought to originate in the anterior cingulate cortex (Ruchsow, Grothe, Spitzer, Kiefer, 2002).
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Feedback-Related Negativity
• Generated without the individual having a choice in responding (Yeung, Holroyd, & Cohen, 2005)
• Generated without the individual responding (Donkers, Nieuwenhuis, & van Boxtel, 2005)
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Feedback Negativity
0.1-30Hz @ 250HzFriday, January 14, 2011
Feedback Negativity
0.1-30Hz @ 250HzFriday, January 14, 2011
Scalp Topographies
Win [Average: 19_7622f_rps.ref] Draw [Average: 19_7622f_rps.ref] Lose [Average: 19_7622f_rps.ref]00:00:00.200
11.2
-11.5
Win Draw Lose
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+
?
You Lose
Rock, Paper, Scissors
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CNV - Contingent Negative Variation
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CNV - Contingent Negative Variation
Negative deflection.
Typically elicited in a Go/No-go paradigm between a warning stimulus (S1) and an imperative stimulus (S2).
Can sub-divide into early & late components.
Early component = "O" or "Orienting" wave.
Late component = "E" or "Expectancy" wave. Thought to reflect anticipation of a
response to S2.
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Habituation
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Habituation
Decline in amplitude & latency after repeated presentations (~ 3 trials)
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Habituation
Decline in amplitude & latency after repeated presentations (~ 3 trials)
Amplitude rebounds after stimulus change
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Habituation
Decline in amplitude & latency after repeated presentations (~ 3 trials)
Amplitude rebounds after stimulus change
Fixed, short ISI and repeating same stimulus enhance habituation effects
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QUESTIONS ???
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ERP Paradigms
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ERP Paradigms
Strengths and weaknesses
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ERP Paradigms
Strengths and weaknesses Guides research
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ERP Paradigms
Strengths and weaknesses Guides research Often different from main stream
behavior-based literature
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ERP Paradigms
Strengths and weaknesses Guides research Often different from main stream
behavior-based literature Can create tunnel-vision effects
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Research Paradigm Effects
ERP & Language:Recent Research History
Over The Last Four Decades
ERP Paradigms
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1970 - 1979Begleiter & Platz (1969). N100---P160 - N400Buchsbaum & Fedio (1969). P190 - 280Buchsbaum & Fedio (1970). P190 - 280Cohn (1971) N30-50 P125Wood, Goff, & Day (1971).! N100Shelburne (1972). P165 - 245, P285Molfese (1972) N100 - P200Matsumiya et al. (1972). P60-N90-P140- N180Lenhardt (1973). N100 P200Dorman (1974).!! ( N75 - P225) Neville (1974) N100 P180 N220Wood (1975)!!! !N100Friedman et al. (1975) N100 P300Galambos et al. (1975) N100 P300 *Shucard et al. (1977).Chapman et al. (1977). * Kostandov & Arzumanov (1977). N200 P300Chapman et al. (1978). *Molfese (1978a).!!!! N45 P135 ! N450Molfese (1978b).!!!! N70 P300Molfese (1979). N100 P300Molfese (1979). P60 N250 P300 N370Pace, et al. 1979).Molfese (1979).Hillyard & Woods (1979) N100 N500Chapman et al. (1979). *
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1980 - 1984
Chapman et al. (1980). *Grabow et al. (1980).Kutas, & Hillyard, 1980 (V) N400Molfese (1980a). (N110 - P190) P330Molfese (1980b).! P170 N460Molfese, Erwin, & Deen (1980).! P198 Neville (1980) N100 P180 Papanicolaou (1980). P92 N133Boddy & Weinberg, (1981) N1 P2 P3Lawson & Galliard (1981a).! N100 - 200Lawson & Galliard (1981b).! N100 - 200Jacobson & Gans (1982).! N100 - 200Kutas & Hillyard (1982) (V) N400Neville et al. (1982).Fischler et. al. (1983) (V) N400Fischler et al (1983). N340Gelfer (1983).! P160Kutas & HIllyard (1983) P200-700 N300-400 P400 - 700 Kutas & Hillyard (1983) (V) N300 - 400, N400 700Molfese & Schmidt (1983).! N70 P170 P290 N460Papanicolaou et al. (1983). N78 P167Polich & McCarthy. (1983) P300Ritter et al. (1983)Rugg (1983a) P670Rugg (1983b) N100 - P187 P300 P637Fischler et al (1984). N320 - N480 McCallum et al. (1984) (A) N212 N456 Molfese (1984). N100 P300 N400 ! P500
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1985 - 1989Fischler et al (1985). N320Fischler et. al. (1985) (V) N400Molfese (1985).Molfese & Molfese (1985).Molfese, et al. (1985). P315 ! N475Molfese, Buhrke, & Wang (1985). ! N95 ! Molfese, Buhrke, & Wang (1985). ! ! P340Novick et al. (1985).Pollich (1985). (V) N400Boddy, (1986) N1 P2 N340Erwin (1986). N45 N350 N485Licht et al. (1986). Lovrich et al. (1986) P250 N310 P445 P485 Molfese & Searock (1986). N 100 ! P150 !N260 N390 N470Neville et al., (1986) (V) N150 P220 N410Bentin, (1987) N400Herning et al. (1987) P250 N480Katayama et al (1987). P300 N310Rugg, (1987) P300 N400Rugg, (1987) N140 P200 LPCHolcomb (1988) N400 Licht et al. (1988). N530Lovrich et al. (1988) N310 P350-375 P540 O'Halloran et. al. (1988) (V) N400Pollich et al (1988) P300Czigler & Szenthe (1989) 300 600Segalowitz & Cohen (1989). P35 N135 ! N390Segalowitz & Cohen (1989). N85 N220 ! N435
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1990 - 1992Barrett et. al. (1990) (V) N400Holcomb & Neville (1990) N2 N400 *Sams et al. (1990) N100 N220Stewart & Connolly (1990) (V) N200 N400Van Petten & Kutas (1990) (V) N400 Ardal et. al. (1991) (V) N400Erwin et al. (1991). N200Neville et al. (1991) N125 P2 N300 - N400 P500 - 700Van Petten et al. (1991) N400 Besson, et al., 1992 (V) N400 Connolly,et al., 1992 (A) N200 N400Gunter et al. (1992) (V) P260 N340 P550Koyama et al. (1992) N370 LPC Kraus et al. (1992) N235Nigam et al. (1992) (V) N400Osterhout &Holcomb (1992) N350 - 500 P600
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1993 - 1994 Bentin et al, (1993) N100 N400 Berman et al. (1993) P350 P600 Curran, et al., 1993 (V) N450 LPC Friederici et al. (1993) N180 N400 P600 Hagoort et al. (1993) N250-600 (P500 700 Karniski,et al., 1993 (A) N250 SW (418 - 530) Kraus et al. (1993) N100 N215-N238 P3aKutas (1993) (V) N400Lovrich et al. (1993) P475 Mitchell et. al. (1993) (V) N400Osterhout & Holcomb (1993) [A] P50 300 RH P300 500RH, PZ N500 800LH Praamstra et al. (1993) N400 [late negativity] Rosler et al (1993) N400 _ 700Rosler et al. (1993) N400-700 P700 1200 *Sharma et al (1993). N200 - P300Van Petten (1993) (V) N400Connolly, et al. (1994) (A) N400 Gunter et. al. (1994) (V) N400Lovrich et al. (1994) N2 P300 P600Munte et al. (1994) N100 P580Nobre et al, (1994) (V) N332 N386 N410 Osterhout et al. (1994) N350 - 450 P500 800LHPerez-Abalo et al. (1994) N400 N450Pratarelli et al. (1994) N1 - P2 N400 St George et. al. (1994) (V) N400
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1995 - 1998
Chwilla et al. (1995) P300 N400 Connolly, et al., (1995) (V) N270 N365 Friederici (1995) (V/A) N400 Friederici (1995) N200 N400 P600 Hamberger et al (1995) P380 N400 P600 Kraus et al. (1995) N100 N200Kuperman et al. (1995) N400 *Maiste et al (1995) N60-120 N120 - P210 ! P500 - 700Mecklinger et. al. (1995) (V) N400Pulvermuller et al. (1995) N160 P200 N340 - 500 N600 - 1000 Schlaghecken et al. (1995) N400 LPC Friederici et al. (1996) N370 N400 500 Hagoort et al. (1996) P2 N400 McKinnon & Osterhout (1996) N1 P2 N400 Nizikiewicz et al., (1996) (V) N200 N400Kazmerski & Friedman 1997) P3 N400 Lovrich et al. (1997) N480Swab et al. (1997) N400 Brualla et al. (1998) N400 N570 N680Gunter et al. (1998) N1 P2 N400 Kiefer et al. (1998) P2 N400 Kutas et al., (1998) (V) N200 N400McPherson et al. (1998) N350 N450 Moute et al., (1998) (V) N250 N400Paller et al (1998) 300 750 Pratarelli et al. (1998) P2 N400
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QUESTIONS ???
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