Action potential as a pressure pulse propagating in the axoplasm

TL;DR

This paper proposes a novel model where action potential propagation is driven by a pressure pulse in the axoplasm, explaining various phenomena and matching experimental data better than previous models.

Contribution

It introduces a pressure pulse-based model for nerve impulse propagation that accounts for mechanical, optical, and thermodynamic phenomena, extending beyond Hodgkin-Huxley's framework.

Findings

Predicts nerve impulse velocity accurately

Explains the Meyer-Overton rule for anesthetics

Accounts for mechanical and optical phenomena

Abstract

We suggest that the propagation of the action potential is driven by a pressure pulse propagating in the axoplasm along the axon length. The pressure pulse mechanically activates Na ion channels embedded in the axon membrane. This activation initiates the development of a local membrane voltage spike, as in the Hodgkin-Huxley model of the action potential. Extracellular Ca ions influxing during the voltage spike trigger a mechanism that amplifies the pressure pulse and therefore prevents its viscous decay. The model is able to explain a number of phenomena that are unexplained within the Hodgkin-Huxley framework: the Meyer-Overton rule for the effectiveness of anesthetics, as well as various mechanical, optical and thermodynamic phenomena accompanying the action potential. The model correctly predicts the velocity of propagation of the nerve impulse, including its dependence on axon diameter, degree of myelination and temperature.