Similarities between action potentials and acoustic pulses in a van der Waals fluid

TL;DR

This paper proposes that action potentials in cells can be better understood as acoustic pulses in lipid interfaces near phase transition, highlighting similarities in properties and suggesting new perspectives beyond electrical measurements.

Contribution

It introduces a theoretical model showing that acoustic pulses in lipid monolayers near phase transition mimic action potentials, offering a new interpretation of nerve signal propagation.

Findings

Acoustic pulses and action potentials share similar properties like shape and velocity.

Action potentials exhibit all-or-none response and collision annihilation.

Temperature changes accompany pulse propagation, indicating a thermodynamic component.

Abstract

An action potential is typically described as a purely electrical change that propagates along the membrane of excitable cells. However, recent experiments have demonstrated that non-linear acoustic pulses that propagate along lipid interfaces and traverse the melting transition, share many similar properties with action potentials. Despite the striking experimental similarities, a comprehensive theoretical study of acoustic pulses in lipid systems is still lacking. Here we demonstrate that an idealized description of an interface near phase transition captures many properties of acoustic pulses in lipid monolayers, as well as action potentials in living cells. The possibility that action potentials may better be described as acoustic pulses in soft interfaces near phase transition is illustrated by the following similar properties: correspondence of time and velocity scales, qualitative pulse shape, sigmoidal response to stimulation amplitude (an `all-or-none' behavior), appearance in multiple observables (particularly, an adiabatic change of temperature), excitation by many types of stimulations, as well as annihilation upon collision. An implication of this work is that crucial functional information of the cell may be overlooked by focusing only on electrical measurements.