EFFECTS OF BILATERAL AUDITORY CORTICAL-LESIONS ON GAP-DETECTION THRESHOLDS IN THE FERRET (MUSTELA-PUTORIUS)

Ferrets were tested for their ability to detect temporal gaps in noise before and after bilateral lesions of the primary auditory cortex. Th resholds for gap detection were determined first for normal animals wi th band-pass noises at various center frequencies (0.5 to 32 kHz) and at 8 kHz with various sound pressure levels (-10-70 dB). Gap-detection ability improved steadily as sound pressure increased up to 70 dB. No systematic relation was found between threshold and center frequency. To determine the effects of brain damage, ferrets were tested with 8- kHz band-pass noise at 70 dB(SPL). After bilateral lesions of auditory cortex, ferrets were still capable of detecting gaps, but the mean th reshold was elevated from 10.1 to 20.1 ms. The data demonstrate that a uditory cortex is important for perceptual tasks requiring fine tempor al resolution.