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TitleLinking demyelination to compound action potential dispersion with a spike-diffuse-spike approach.
Publication TypeJournal Article
Year of Publication2019
AuthorsNaud, Richard, and Andre Longtin
JournalJ Math Neurosci
Date Published2019 May 30

To establish and exploit novel biomarkers of demyelinating diseases requires a mechanistic understanding of axonal propagation. Here, we present a novel computational framework called the stochastic spike-diffuse-spike (SSDS) model for assessing the effects of demyelination on axonal transmission. It models transmission through nodal and internodal compartments with two types of operations: a stochastic integrate-and-fire operation captures nodal excitability and a linear filtering operation describes internodal propagation. The effects of demyelinated segments on the probability of transmission, transmission delay and spike time jitter are explored. We argue that demyelination-induced impedance mismatch prevents propagation mostly when the action potential leaves a demyelinated region, not when it enters a demyelinated region. In addition, we model sodium channel remodeling as a homeostatic control of nodal excitability. We find that the effects of mild demyelination on transmission probability and delay can be largely counterbalanced by an increase in excitability at the nodes surrounding the demyelination. The spike timing jitter, however, reflects the level of demyelination whether excitability is fixed or is allowed to change in compensation. This jitter can accumulate over long axons and leads to a broadening of the compound action potential, linking microscopic defects to a mesoscopic observable. Our findings articulate why action potential jitter and compound action potential dispersion can serve as potential markers of weak and sporadic demyelination.

Alternate JournalJ Math Neurosci
PubMed ID31147800
PubMed Central IDPMC6542900
Grant ListRGPIN-2017-06872 / / NSERC /
RGPIN-2014-06204 / / NSERC /
610820-151999-211 / / Canadian Neurophotonics Platform /