Inhibition of Auditory Nerve Activity by Acoustic Stimulation

Abstract

For each single auditory-nerve fiber (cat) there is a “response area” clearly defined in terms of the frequency and intensity of the tones which excite activity. For most fibers the discharge of nerve impulses aroused by such adequate tones (T1) can be reduced or abolished by other tones (T2) or by noises (hiss or rattle) presented concurrently. Not all tones inhibit the response to T1. Those which do inhibit fall into one or more well-defined “inhibitory areas” which are different for different fibers and for different T1's presented to a given fiber. The inhibitory areas are adjacent to the response areas and often include some tones which lie within the response area. For a few fibers no single pure tone (T2) inhibits the response to T1, but in such cases the activity can usually still be abolished by noises. Inhibition of auditory-nerve activity by acoustic stimulation might result from mechanical interference in the auditory receptor or from neural interaction. Control experiments seem to exclude mechanical interference at the middle ear or basilar membrane level as an explanation. The possibility that neural interaction is involved and its implications for the interpretation of masking will be discussed.