Open AccessEphaptic coupling in white matter fibre bundles modulates axonal transmission delays
Author(s) -
Helmut Schmidt,
Gerald J. Hahn,
Gustavo Deco,
Thomas R. Knösche
Publication year - 2021
Publication title -
plos computational biology/plos computational biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.628
H-Index - 182
eISSN - 1553-7358
pISSN - 1553-734X
DOI - 10.1371/journal.pcbi.1007858
Subject(s) - extracellular , neuroscience , stimulus (psychology) , depolarization , coupling (piping) , neurotransmission , axon , biophysics , membrane potential , physics , white matter , chemistry , biology , materials science , psychology , microbiology and biotechnology , medicine , magnetic resonance imaging , metallurgy , psychotherapist , radiology , biochemistry , receptor
Axonal connections are widely regarded as faithful transmitters of neuronal signals with fixed delays. The reasoning behind this is that extracellular potentials caused by spikes travelling along axons are too small to have an effect on other axons. Here we devise a computational framework that allows us to study the effect of extracellular potentials generated by spike volleys in axonal fibre bundles on axonal transmission delays. We demonstrate that, although the extracellular potentials generated by single spikes are of the order of microvolts, the collective extracellular potential generated by spike volleys can reach several millivolts. As a consequence, the resulting depolarisation of the axonal membranes increases the velocity of spikes, and therefore reduces axonal delays between brain areas. Driving a neural mass model with such spike volleys, we further demonstrate that only ephaptic coupling can explain the reduction of stimulus latencies with increased stimulus intensities, as observed in many psychological experiments.