Suppression of auditory nerve discharges by a contralateral stimulus

Abstract

Single‐unit activity was recorded from the cochlear nerve of cats immobilized by Flaxédil. The ipsilateral ear was just above threshold; the contralateral stimulus was the same except the intensity was varied. Most neurons responded to strong contralateral tones as well as to the ipsilateral stimulus. When the stimuli to the two ears were presented simultaneously the response clearly showed direct mechanical interaction between the two sounds in the ipsilateral cochlea. In addition, for a few neurons an intense contralateral stimulus suppressed more or less completely the response to ipsilateral sound as well as the spontaneous activity. The latency and time course of suppression and recovery from it were too slow to be due to monaural two‐tone suppression, but seemed to resemble those of the inhibition induced by electrical stimulation of the crossed olivo‐cochlear bundle beneath the floor of the 4th ventricle.