The effects of selective inner hair cell loss on auditory evoked potentials recorded from multiple levels of the auditory system of the unanesthetized chinchilla

Abstract

Most animal models of sensorineural hearing loss show either selective outer hair cell (OHC) loss, or combined OHC and inner hair cell (IHC) loss. Several years ago, Robert Harrison and colleagues discovered that carboplatin could produce a selective IHC loss in the chinchilla. Carboplatin is a second-generation, platinum-based anti-neoplastic agent. In chinchillas, the effect of carboplatin administered systemically is dose dependent, and for the appropriate dosage, produces selective, patchy IHC loss that extends the length of the cochlea. As the vast majority of auditory-nerve afferents innervate the IHCs, this patchy IHC loss due to carboplatin leads to a partial deafferentation of the cochlea. This invited presentation will review a series of studies investigating near-field auditory evoked potentials in the chinchilla that have been performed at the University at Buffalo by the author and his colleagues. Chronic electrode implantation combined with passive animal restraint allow us to record from unanesthetized animals, thus avoiding the confounding effects of anesthesia. Responses from multiple levels of the nervous system (e.g., round window, auditory nerve, inferior colliculus, auditory cortex) will be reported, comparing responses before and after inducing partial IHC loss. [Work supported by NIH NICDC DC03600.]