Contribution of auditory cortex to acoustical orientation in cats under conditions of discordant auditory reafference.

Head-orienting responses (ORs) evoked by a stationary source of sound typically terminate in small undershoots in normal hearing cats or in large undershoots (hypometria) if the auditory cortex is ablated bilaterally. In the present study, ORs executed by cats were studied using a procedure in which the OR produced an isogonal rotation of the sound source, i.e., response-produced change (reafference) in the acoustic stimulus was distorted. Under this condition (discordant auditory reafference), ORs terminated in large overshoots (hypermetria) in the normal hearing cats. This result indicates that experimental distortion of response-produced auditory feedback resulted in an "on-line" modification of ORs by the normal hearing cats. In the cats with auditory cortex ablated, ORs terminated in large undershoots (hypometria), suggesting that auditory cortex is a necessary component of the central auditory system for processing reafferent acoustic stimuli that normally occur during head rotation in a sound field.