11. introduction to neuronal networks - berg-lab. · pdf file11. introduction to neuronal...
TRANSCRIPT
11. Introduction to neuronal networks:
Molekylær biomedicin
Cellular Neuroscience module09/06/2008
Notes are available on Absalon
Rune W. Berg12.5.5Tel. 35 32 75 [email protected]/runeb
Main paper: Vogels et al 2005
Just talked about
Afferent - convergent - divergent connections
Feedback - feedforward connections. Thalamo-cortical loop
Principal and interneurons
3 basic types of networks - Small world most beneficial
overview
Network models: Internally generated activity
Practical measures: Rastogram, extracellular measures
Coding models: Temporal and rate codes
Coin experiment
4 Patterns of spike activity
Signal propagation, avalanche and synfire model
Brain is never quiet…
Vogels, Rajan & Abbott 2005
Sensory induced activity (observing)
Internally generated activity (thinking, sleeping)
Internally generated activity
Vogels, Rajan & Abbott 2005
3 forms of network activity:
Persistent
Oscillatory
Asynchronous and irregular
exploring the neural code?
Measures of activity:rastogram
Berg et al 2007
Measures of activity:Extracellular fields
Buzsaki 2004
The electric field from groups of neurons is an indication of the state of the network
ECoG, EEG, LFP, CSD
ElectroCorticoGramElectroEncephaloGraphyLocal Field PotentialCurrent Source Density
Example:Hippocampus
Hammond 2008
Coding strategies
Shadlen & Newsome 1998, Buzsaki et al 2004
Frequency or rate code
= sum of events in time window
Temporal code
Coding strategies
Shadlen & Newsome 1998, Buzsaki et al 2004
Frequency or rate code
= sum of events in time window
Temporal code
Coding strategies
Shadlen & Newsome 1998, Buzsaki et al 2004
Frequency or rate code
= sum of events in time window
Temporal code
Coding strategies
Shadlen & Newsome 1998, Buzsaki et al 2004
Frequency or rate code
= sum of events in time window
Temporal code
Coding strategies
Shadlen & Newsome 1998, Buzsaki et al 2004
Frequency or rate code
= sum of events in time window
Temporal code
Rate code: Muscles
Temporal code: visual cortex
Singer 1999
“Binding theory” : 40-Hz synchrony
Example:Hippocampus
Hammond 2008
Example:Hippocampus
Hammond 2008
Coin Experiment
Camazine 2003
1) single group response
2) group noise during synchrony and non-synchrony
3) group response during synchrony
Synchrony
Camazine et al 2003
Group responsein-synchrony
Single group response
4 patterns of spike activity
Vogels, Rajan & Abbott 2005
Regular spiking
Irregular spiking
Synchronous with other neurons
Asynchronous with other neurons
Asynchronous regular,Synchronous regular
Vogels, Rajan & Abbott 2005
Irregular - asynchronous
Vogels, Rajan & Abbott 2005
Irregularity from balanced Inhibitory and excitatory Input.
Propagation
How do signals propagate in a network?
Avalanche model
Vogel et al 2005, Pletz & Thiagarajan 2007
An avalanche of neural activity is a brief and temporary propagation of activity which amplitude has a power log probability with negative slope
Np > 1 explosionNp < 1 failure
P(s) proportional s ^-a
Like Small-world networks
Buzsaki et al. 2004
P(s) proportional s ^-a
Synfire chains
Vogel et al 2005
Groups of neurons coupled in a feedforward manner.
Synfire chains
Vogel et al 2005
Summary
Network models: Internally generated activity
Practical measures: Rastogram, extracellular measures
Coding models: Temporal and rate codes
Coin experiment
4 Patterns of spike activity
Signal propagation, avalanche and synfire model
Further reading:Berg RW, Alaburda A, Hounsgaard J (2007) "Balanced inhibition and excitation drive spike activity in spinal half-centers" Science vol. 315 (5810) pp. 390-393
Buzsaki G (2004) "Large-scale recording of neuronal ensembles" Nature Neuroscience vol. 7, 446-451
Buzsaki G, Geisler C, Henze DA, Wang X-J (2004) "Interneuron diversity series: Circuit complexity and axon wiring economy of cortical interneurons" Trends in Neurosciences vol. 27(4) 186-193
Camazine S et al (2003) "Self-organization in biological systems" Princeton University Press, paperback.
Dyhrfjeld-Johnsen J, Santhakumar V, Morgan RJ, Huerta R, Tsimring L, Solstesz I (2007) "Topological determinants of epileptogenesis in large-scale structural and functional models of the dentate gyrus derived from experimental data" J. Neurophysiol. 97: 1566-1587
Hammond C (2008) "Cellular and molecular neurophysiology” Academic press, 3rd edition.
Shadlen, M. N., W. T. Newsome (1998), "The variable discharge of cortical neurons: Implications for connectivity, computation, and information coding", J. Neuroscience, 18(10): 3870-3896, 1998
Singer W (1999) "Neural synchrony: A versatile code for the definition of relations?" Neuron vol. 24, 49-65
Steriade M, McCormick DA, Sejnowski TJ (1993) "Thalamocortical oscillations in the sleeping and aroused brain" Science vol. 262, 679-685.
Strogatz SH (2001) "Exploring complex networks" Nature 410, 268-276
Vogels TP, Rajan K, Abbott LF "Neural network dynamics" Annual review of neuroscience, vol 28: 327-355 (2005)Watts DJ, Strogatz SH (1998) "Collective dynamics of 'small-world' networks" Nature 393(6684) 409-10.