Failure of feedback as a putative common mechanism of spreading depolarizations in migraine and stroke

TL;DR

This paper investigates how feedback failure may serve as a common mechanism for spreading depolarizations in migraine and stroke, using reaction-diffusion models to understand propagation and control of cortical disturbances.

Contribution

It proposes a reaction-diffusion model with nonlocal feedback to explain spreading depolarizations and explores how feedback parameters influence propagation suppression.

Findings

Spreading depolarizations can be modeled by reaction-diffusion systems with feedback.

Proper feedback tuning can shift bifurcation points to suppress propagation.

Diffusion contributes to the velocity of cortical depolarizations.

Abstract

The stability of cortical function depends critically on proper regulation. Under conditions of migraine and stroke a breakdown of transmembrane chemical gradients can spread through cortical tissue. A concomitant component of this emergent spatio-temporal pattern is a depolarization of cells detected as slow voltage variations. The velocity of ~3 mm/min indicates a contribution of diffusion. We propose a mechanism for spreading depolarizations (SD) that rests upon a nonlocal or non-instantaneous feedback in a reaction-diffusion system. Depending upon the characteristic space and time scales of the feedback, the propagation of cortical SD can be suppressed by shifting the bifurcation line, which separates the parameter regime of pulse propagation from the regime where a local disturbance dies out. The optimisation of this feedback is elaborated for different control schemes and ranges of control parameters.