Propagation Failure Along Myelinated Nerves

Abstract

Propagation of traveling pulses in the myelinated Hodgkin-Huxley model is studied. The nerve impulse is a traveling wave with two components. At the Ranvier nodes, it behaves as a discrete traveling pulse. Wave motion through the internodal regions is then driven by this traveling pulse. We give analytical characterizations of the parameter ranges for which nerve impulses fail to propagate by exploiting time scale separation and the active node approximation, which reduces the dynamics of infinite fibers to the evolution of a few nodes. Simple recipes to predict the speed of the impulses and the widths of their peaks are also given. Predictions are in good agreement with the information provided by numerical simulations.