Suppression of auditory nerve responses I: temporal analysis, intensity effects and suppression contours.

Two-tone suppression was studied in response patterns of single auditory nerve fibers in anesthetized cats. Utilizing suppression of discharge synchronization in response to low- and moderate-frequency tones as an index, it was found that (a) suppression behaves in the same manner when the suppressor tone presented alone is strongly excitatory as when it is ineffective in altering discharge rate; (b) suppression exists throughout an auditory nerve fiber's response area; (c) for fixed-intensity suppressors, suppression is maximal at a fiber's characteristic frequency; and (d) suppression magnitude over a wide intensity range depends only upon the parameters of the suppressor tone and not of the tone being suppressed. The data are in general agreement with previously published reports of suppression behavior, and they support the concept that suppression is generated primarily as a result of interactions occurring within hair cells or in the subtectorial space.