Eugene M. Izhikevich

The Neurosciences Institute, San Diego, CA

"Spike-Timing Resonances in Cortical Networks with Conduction Delays"

In the mammalian neocortex, pyramidal neurons often project to distant regions resulting in axonal conduction delays of tens of milliseconds.

Synchronous spiking of such neurons may not be effective to fire a given postsynaptic cell, since the spikes might arrive to the postsynaptic cell at drastically different times. To excite the cell, the presynaptic neurons must fire with certain spike-timing patterns determined by the delays.

Simulating a network of neocortical neurons with conduction delays and spike-timing dependent plasticity (STDP), we found that spiking neurons spontaneously self-organized into stable groups and fire such repetitive spike-timing patterns with a millisecond precision. To our surprise, the number of such groups far exceeded the number of neurons in the network, resulting in an unprecedented memory capacity of the system. We discuss possible implications of this finding for the information processing by the brain.