UCL Logo

John Hertz
NORDITA, Copenhagen, Denmark



Tuesday 20 September 2005



Seminar Room B10 (Basement)

Alexandra House, 17 Queen Square, London, WC1N 3AR



Self-Organization in Cortical Networks?


Recent experiments on cortical circuits, both in vitro and in vivo, have revealed the existence of near-synchronous population bursts in background firing activity.  We have simulated networks of leaky integrate-and-fire neurons (80% excitatory, 20% inhibitory) with conductance-based synapses and parameters chosen so that the average synaptic conductance at average firing rates 1-2 Hz matches measured values.  The connectivity is random (Erdos-Renyi); in the results described here we used a connection probability of 20%.  We find bursty behaviour like that observed experimentally.  There is a power-law distribution, possibly indicative of some kind of self-organized critical state, for the total network activity, with an exponent near -2.5.