Behavioral evaluation of electrolytic lesions in the cochlea

Pure‐tone thresholds of normal chinchillas were determined by the shock‐avoidance procedure. Under aseptic conditions, differential electrodes were placed in a given turn of the cochlea microphonic (CM) response was measured. The cochlea was then electrolytically lesioned with the method described by Ferraro and Dallos [J. Acoust. Soc. Am. 55, S78(A) (1974)]. Holes in the cochlear bone and the bulla were sealed, the contralateral cochlea destroyed, and the animal allowed to recover. Pure‐tone thresholds were determined daily, until the observed shift to threshold had stabilized. Each animal was then anaesthetized and further electrophysiological data collected. Finally, the animal was sacrificed and the ear prepared for histological examination. Lesions required several days to stabilize. Correlations between behavioral, electrophysiological, and histological measures were good. [This research was supported by grants from NINDS.]