introduction to neuronal networks 2 - rune w. · pdf fileintroduction to neuronal networks 2:...

Introduction to neuronal networks 2:

Dynamics

Molekylær biomedicin

Cellular Neuroscience module04/05/2009

Notes are available on Absalon

Rune W. Berg12.5.5Tel. 35 32 75 60rune@mfi.ku.dkwww.berg-lab.net

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,Tetrodes for spike sorting

ElectroCorticoGramElectroEncephaloGraphyLocal Field PotentialCurrent Source DensityTetrode= 4 (tetra) eletrodes

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

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.

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

Asynchronous regular,Synchronous regular

Vogels, Rajan & Abbott 2005

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

pn > 1 explosionpn < 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.