Two-dimensional wave patterns of spreading depolarization: retracting, re-entrant, and stationary waves

TL;DR

This paper investigates the complex spatio-temporal patterns of spreading depolarizations in the brain, using experimental observations and a reaction-diffusion mathematical model to explain re-entrant, retracting, and stationary wave behaviors relevant to migraine and stroke.

Contribution

It introduces a reaction-diffusion framework with nonlocal coupling to explain diverse SD wave patterns observed experimentally in retina and cortex.

Findings

Re-entrant SD waves can spread repeatedly across cortex.

Retracting SD segments are observed in chicken retina.

Transitions to stationary SD patterns may relate to persistent symptoms.

Abstract

We present spatio-temporal characteristics of spreading depolarizations (SD) in two experimental systems: retracting SD wave segments observed with intrinsic optical signals in chicken retina, and spontaneously occurring re-entrant SD waves that repeatedly spread across gyrencephalic feline cortex observed by laser speckle flowmetry. A mathematical framework of reaction-diffusion systems with augmented transmission capabilities is developed to explain the emergence and transitions between these patterns. Our prediction is that the observed patterns are reaction-diffusion patterns controlled and modulated by weak nonlocal coupling. The described spatio-temporal characteristics of SD are of important clinical relevance under conditions of migraine and stroke. In stroke, the emergence of re-entrant SD waves is believed to worsen outcome. In migraine, retracting SD wave segments cause neurological symptoms and transitions to stationary SD wave patterns may cause persistent symptoms without evidence from noninvasive imaging of infarction.