Background and Evoked Activity in the Auditory Pathway: Effects of Noise-Shock Pairing

Unanesthetized cats with electrodes permanently implanted along the auditory pathway were presented first with suistained " white" noise stimuli and then with the same noise paired with subcutaneous electric shocks. Pairing noise with shock decreased both background and noise-evoked activity inthe inferior colliculus, and, in some cats, also in the cochlear nucleus, trapezoid body, and at the round window. No changes occurred in medial geniculate or auditory cortex recordings. The effects in the inferior colliculusdo not depend on changes in the degree of arousal of the animal, on change in the medullary auditory areas, or on the actions of the middle-ear muscle.