Effect of channel noise on spike propagation in myelinated axons

Abstract

Voltage-gated ion channels embedded in neuronal membranes are stochastic devices fluctuating randomly between open and close states. These fluctuations results in noisy membrane currents and subthreshold oscillations. The intensity of the ion channel noise is inversely related to the cell size (or the total number of ion channels): the smaller the cell size, the larger the intensity of channel noise. When the cell size is large enough, stochastic effects of the channel noise becomes negligible and the collective dynamics approaches the deterministic description. However, when the cell size is small, their stochastic behaviors have significant impacts on the membrane dynamics. The generated spikes (or action potentials) are propagated through an axon. In many vertebrates, the propagation of the spikes is mediated by myelinated axons, where the voltage-gated ion channels are accumulated in the nodes of Ranvier. Therefore, the stochastic behavior of the channels in these nodes affects the spike propagation. In this study, the impact of channel noise on the spike propagation through myelinated axons is examined by using a compartmental stochastic axon model.