introduction to neuronal networks 2 - rune w. · pdf fileintroduction to neuronal networks 2:...
TRANSCRIPT
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 [email protected]
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.