DESTRUCTION OF THE AUDITORY THALAMUS DISRUPTS THE PRODUCTION OF FEAR BUT NOT THE INHIBITION OF FEAR CONDITIONED TO AN AUDITORY STIMULUS

The auditory thalamus is part of a neural circuit that mediates the ex pression of fear to auditory stimuli. Bilateral lesions of the auditor y thalamus prevent the expression of fear to an auditory stimulus pair ed with shock. The present study assessed whether bilateral lesions of the auditory thalamus would also disrupt the inhibition of fear to an auditory stimulus paired with the absence of shock. Rats were given b ilateral lesions of the auditory thalamus followed by PavIovian condit ioned inhibition training in which a light was paired with shock and a noise and light compound was presented in the absence of shock. Fear and the inhibition of fear were measured with the fear-potentiated sta rtle effect. Lesions of the auditory thalamus did not disrupt the abil ity of the noise to inhibit the expression of fear to the light. Howev er, these lesions did disrupt the ability of the noise to produce fear -potentiated startle after it had been subsequently paired with shock. These results suggest that although the auditory thalamus is an essen tial part of a neural circuit that mediates the expression of fear to auditory stimuli, it is not an essential part of the circuit that medi ates the inhibition of fear to auditory stimuli. (C) 1998 EIsevier Sci ence B.V. All rights reserved.