Stochastic Ion Channel Gating and Probabilistic Computation in Dendritic Neurons

Abstract

The electrical signals underlying neural computations are mediated by membrane ion channels. Although these ion channels are well known to operate stochastically, most computational models of dendritic neurons instead make the approximation that ionic conductances are deterministic. We review the basic mathematical considerations underlying this approximation and new efficient simulation tools that allow it to be evaluated systematically. We show how this approximation breaks down for dendritic neurons, with the relative functional influence of stochastic ion channel gating likely to depend strongly on neuron type. An important consequence of stochastic gating of ion channels may be that it causes dendritic neurons to integrate synaptic inputs probabilistically, rather than in the all or nothing fashion predicted by deterministic models.