Ionic mechanisms underlying history-dependence of conduction delay in an unmyelinated axon
- New Jersey Institute of Technology, United States
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 due to 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.
Article and author information
Author details
Funding
National Institute of Neurological Disorders and Stroke (NS083319)
- Dirk M Bucher
- Farzan Nadim
National Institute of Mental Health (MH060505)
- Farzan Nadim
National Institute of Neurological Disorders and Stroke (NS058825)
- Dirk M Bucher
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Zhang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Ionic mechanisms underlying history-dependence of conduction delay in an unmyelinated axon
eLife 6:e25382.
https://doi.org/10.7554/eLife.25382
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