Poisson Model of Spike Generation

In the cortex, the timing of successive action potentials is highly irregular. The interpretation of this irregularity has led to two divergent views of cortical organization. On the one hand, the irregularity might arise from stochastic forces. If so, the irregular interspike interval reflects a random process and implies that an instantaneous estimate of the spike rate can be obtained by averaging the pooled responses of many individual neurons. In keeping with this theory, one would expect that the precise timing of individual spikes conveys little information. Alternatively, the irregular ISI may result from precise coincidences of presynaptic events. In this scenario, it is postulated that the timing of spikes, their intervals and patterns can convey information. According to this view, the irregularity of the ISI reflects a rich bandwidth for information transfer.