TY - JOUR TI - Ionic mechanisms underlying history-dependence of conduction delay in an unmyelinated axon AU - Zhang, Yang AU - Bucher, Dirk AU - Nadim, Farzan A2 - Skinner, Frances K VL - 6 PY - 2017 DA - 2017/07/10 SP - e25382 C1 - eLife 2017;6:e25382 DO - 10.7554/eLife.25382 UR - https://doi.org/10.7554/eLife.25382 AB - 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. KW - H. americanus KW - action potential conduction KW - temporal fidelity KW - temporal coding KW - sodium channel KW - activity dependent JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -