Ionic mechanisms underlying historydependence of conduction delay in an unmyelinated axon

Document Type

Article

Publication Date

7-10-2017

Abstract

Axonal conduction velocity can change substantially during ongoing activity, thus modifying spike interval structures and, potentially, temporal coding. We used a biophysical model to unmask mechanisms underlying the history-dependence of conduction. The model replicates activity in the unmyelinated axon of the crustacean stomatogastric pyloric dilator neuron. At the timescale of a single burst, conduction delay has a non-monotonic relationship with instantaneous frequency, which depends on the gating rates of the fast voltage-gated Na+ current. At the slower timescale of minutes, the mean value and variability of conduction delay increase. These effects are because of hyperpolarization of the baseline membrane potential by the Na+/K+ pump, balanced by an h-current, both of which affect the gating of the Na+ current. We explore the mechanisms of history-dependence of conduction delay in axons and develop an empirical equation that accurately predicts this history-dependence, both in the model and in experimental measurements.

Identifier

85027152903 (Scopus)

Publication Title

Elife

External Full Text Location

https://doi.org/10.7554/eLife.25382

e-ISSN

2050084X

PubMed ID

28691900

Volume

6

Grant

R01MH060605

Fund Ref

National Institute of Mental Health

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