Comparison of rapid and short-term adaptation in the auditory nerve

Abstract

Events during the first few milliseconds of auditory-nerve adaptation appear to differ qualitatively from those occurring later on. This has previously been revealed using PST analysis with various bin-width sizes, and also by dissecting the perstimulatory response into two components: rapid and short-term adaptation. In order to further evaluate the extent of these differences, a series of perstimulatory and post-stimulatory comparisons were made involving the recovery from prior stimulation and the effects of sound frequency and intensity. Post-stimulatory effects on both rapid and short-term firing rates appear to be proportional to the magnitude of the conditioning or adapting response, and otherwise to be independent of sound frequency. Following stimulation, the rapid component recovers more quickly than does the short-term component. Changes in sound frequency do not alter the amount of perstimulatory short-term adaptation, but effect the rapidly adapting component in a complex manner. This may be due in part to frequency splatter produced by non-CF tones, and also to phase locking to individual cycles of low-frequency tones. Implications for models of adaptation will be discussed. [Work supported by NSF and NIH.]