Nonlinearities of mechanoelectric transduction in pigeon primary auditory fibers depend on the temporal pattern of their spontaneous activity.

Abstract

Input–output functions (IOFs) were investigated in pigeons’ auditory fibers with random and quasiperiodic spontaneous activity (SA) [A. N. Temchin, J. Comp. Physiol. A 163, 99–115 (1988)]. The first group showed regular sigmoidal IOF shape at the characteristic frequency (CF) and the slopes were virtually frequency-independent for each fiber. The second group had nearly linear IOFs only around CF and showed single-tone suppression of SA. At any suppressive frequency the IOF slopes were negative threshold and level at which total suppression occurred (15–20 dB). Positive slope of IOFs increased as the difference between CF and frequency of stimuli increased. Transition from total suppression of SA to saturation occasionally took place within as little as 10 dB. The minimal thresholds of suppression were often 7–8 dB less than thresholds at CF. The results cannot be explained by nonlinearities of basilar membrane and presumably indicate that active electrical properties of avian hair cells are involved in mechanoelectric transduction. [Work supported by Callier-UTD Excellence in Education and M. F. Jonsson Funds.]