Biophysical Model of an Auditory Nerve Fiber With a Novel Adaptation Component

Recent data from feline auditory nerve fibers (ANFs) indicate that electrically stimulated fibers can undergo large degrees of rate adaptation to pulse-train stimuli using pulse rates within the range used by clinical auditory prostheses. However, the application of Hodgkin-Huxley-type models does not produce such adaptation, which occurs over time periods on the order of 100 ms. We describe our development of a computational ANF axon model that incorporates a time-changing external potassium concentration ([K
⁺
]
_ext
) that depends on potassium currents produced by active nodal channel activity. This relatively simple and computationally tractable approach produces poststimulus time histograms that are similar to experimental (cat) data. Furthermore, this mechanism could be easily incorporated into other models to produce much more realistic estimates of the neural coding produced by repeated electric stimulation.