The thermodynamic soliton theory of the nervous impulse and possible medical implications

TL;DR

This paper proposes a thermodynamic soliton model for nerve impulses, emphasizing macroscopic variable couplings over traditional molecular explanations, with implications for medical treatments and neural stimulation techniques.

Contribution

It introduces a thermodynamic soliton framework for nerve impulses, highlighting variable couplings and potential medical applications, contrasting with the traditional molecular ion channel model.

Findings

Thermodynamic couplings explain anesthesia counteractions.

Lithium overdose effects linked to thermodynamic variables.

Ultrasound as a potential neural stimulation method.

Abstract

The textbook picture of nerve activity is that of a propagating voltage pulse driven by electrical currents through ion channel proteins, which are gated by changes in voltage, temperature, pressure or by drugs. All function is directly attributed to single molecules. We show that this leaves out many important thermodynamic couplings between different variables. A more recent alternative picture for the nerve pulse is of thermodynamic nature. It considers the nerve pulse as a soliton, i.e., a macroscopic excited region with properties that are influenced by thermodynamic variables including voltage, temperature, pressure and chemical potentials of membrane components. All thermodynamic variables are strictly coupled. We discuss the consequences for medical treatment in a view where one can compensate a maladjustment of one variable by adjusting another variable. For instance, one can explain why anesthesia can be counteracted by hydrostatic pressure and decrease in pH, suggest reasons why lithium over-dose may lead to tremor, and how tremor is related to alcohol intoxication. Lithium action as well as the effect of ethanol and the anesthetic ketamine in bipolar patients may fall in similar thermodynamic patterns. Such couplings remain obscure in a purely molecular picture. Other fields of application are the response of nerve activity to muscle stretching and the possibility of neural stimulation by ultrasound.