Kainic Acid Lesions of the Superior Olivary Complex: Effects on Sound Localization by the Albino Rat

The ability of rats to localize sounds in space was determined before and after kainic acid lesions of the superior olivary complex (SOC). Animals were tested with a 45-ms noise burst delivered from loudspeakers on the right or left of midline. Anatomical data showed that the lesions destroyed neurons in SOC while preserving fibers of passage in the trapezoid body and other decussating pathways of the auditory brainstem. Animals with either unilateral or bilateral SOC lesions were impaired in their ability to localize a single noise burst postoperatively. Deficits were also found after unilateral lesions restricted primarily to the lateral superior olive. SOC lesions resulted in an elevation in minimum audible angles for sound localization.