Channel Noise in Excitable Neural Membranes

Abstract

Stochastic fluctuations of voltage-gated ion channels generate current and voltage noise in neuronal membranes. This noise may be a criti(cid:173) cal determinant of the efficacy of information processing within neural systems. Using Monte-Carlo simulations, we carry out a systematic in(cid:173) vestigation of the relationship between channel kinetics and the result(cid:173) ing membrane voltage noise using a stochastic Markov version of the Mainen-Sejnowski model of dendritic excitability in cortical neurons. Our simulations show that kinetic parameters which lead to an increase in membrane excitability (increasing channel densities, decreasing tem(cid:173) perature) also lead to an increase in the magnitude of the sub-threshold voltage noise. Noise also increases as the membrane is depolarized from rest towards threshold. This suggests that channel fluctuations may in(cid:173) terfere with a neuron's ability to function as an integrator of its synaptic inputs and may limit the reliability and precision of neural information processing.