Reproducing response characteristics of electrically-stimulated auditory nerve fibers with a phenomenological model

Electrical stimulation of the auditory nerve fibers (ANFs) by a cochlear implant (CI) restores hearing for profoundly deaf people. Modern CIs use sequences of amplitude-modulated charge-balanced pulses to encode the spectro-temporal information of the sound reaching the ears of the listener. In such a pulsatile stimulation, several temporal phenomena related to inter-pulse interactions affect the responsiveness of the ANF during the course of the stimulation. Specifically, refractoriness, facilitation, accommodation, and spike-rate adaptation affect whether a given pulse evokes an action potential or not, and these phenomena continue to provide challenges for computational models. Here, we present a model that builds on recent the biphasic leaky integrate-and-fire model by Horne et al. (Front. Comput. Neurosci. 2016), which we have extended to include elements that simulate refractoriness and facilitation/accommodation by affecting the threshold value of the model momentarily after supra- and subthreshold...