Auditory-nerve spontaneous rates vary predictably with threshold.

The variation of spontaneous rate with auditory nerve thresholds is compared with predictions from a simple assumption: that spontaneous and driven activity are basically similar, both being evoked by inner hair cell transmembrane potential. Under this view, spontaneous activity is seen as a response to a standing current within the hair cell and should therefore vary with threshold in a manner predictable from measured rate-intensity functions. A method for comparing spontaneous rates of fibres with differing thresholds is developed and applied to previously-collected data. The results show that spontaneous rates are quite consistent with the hypothesis, indicating no need for more complicated theories of spontaneous activity.