Synchronous auditory nerve activity in the carboplatin-chinchilla model of auditory neuropathy.

Two hallmark features of auditory neuropathy (AN) are normal outer hair cell function in the presence of an absent/abnormal auditory brainstem response (ABR). Studies of human AN patients are unable to determine whether disruption of the ABR is the result of a reduction of neural input, a loss of auditory nerve fiber (ANF) synchrony, or both. Neurophysiological data from the carboplatin model of AN reveal intact neural synchrony in the auditory nerve and inferior colliculus, despite significant reductions in neural input. These data suggest that (1), intact neural synchrony is available to support an ABR following carboplatin treatment and, (2), impaired spike timing intrinsic to neurons is required for the disruption of the ABR observed in human AN.