Electrophysiological and morphological observations of electrolytically lesioned chinchilla cochleas

Electrolytic lesions were produced in chinchilla cochleas with the method described by Ferraro and Dallos [Arch. Otolaryngol. 101, 312 (1975)]. This procedure involves passing a current of 1–3mA, at an approximate frequency of 5 MHz, for a controlled amount of time between a differential pair of recording electrodes located in a particular cochlear turn. Cochlear microphonic responses were recorded immediately before lesioning and for a period of from one to three hours after lesioning. The cochleas were then perfused with glutaraldehyde, dissected out and prepared for scanning electron microscopic examination with the Murakami technique [Arch. Histol. Jpn. 36, 189 (1974)]. A localized region of destruction of cochlear partition elements located between the electrode tips, progressing from outer to inner hair cells and supporting structures was observed. Cochlear microphonic data and corresponding scanning electron photomicrographs of lesioned cochleas are presented. [This research was supported in part by grants from the Graduate School, and College of Social and Behavioral Sciences, Ohio State University.]