Reliability of Spike Timing in a Neuron Model

Recently, it has been shown experimentally [Mainen & Sejnowski, 1995] that, in contrast to the lack of precision in spike timing associated with flat (dc) stimuli, neocortical neurons of rats respond reliably to weak input fluctuations resembling synaptic activity. This has led authors to suggest that, in spite of the high variability of interspike intervals found in cortical activity, the mechanism of spike generation in neocortical neurons has a low level of intrinsic noise. In this work we approach the problem of spike timing by using the well-known FitzHugh–Nagumo (FHN) model of neuronal dynamics and find that here also, fluctuating stimuli allow a more reliable temporal coding than constant suprathreshold signals. This result is associated with the characteristics of a phenomenological stochastic bifurcation taking place in the noisy FHN model.