11. introduction to neuronal networks - berg-lab. · pdf file11. introduction to neuronal...

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 60rune@mfi.ku.dkwww.mfi.ku.dk/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.