Two-Tone Inhibition in Auditory-Nerve Fibers

Abstract

Spike discharges from single fibers in the auditory nerve of anesthetized cats were recorded with micro-electrodes. Rates of discharge were measured as functions of the frequencies and levels of either single tones or two tones presented simultaneously. We found that the presence of a second tone diminishes the responses to the first tone if appropriate stimulus parameters are chosen. All fibers tested showed this two-tone inhibition. Response areas and inhibitory areas were defined from isorate contours. The general characteristics of the inhibitory areas are found to be similar for a population of over 300 fibers.