Sa. Heldt et Wa. Falls, DESTRUCTION OF THE AUDITORY THALAMUS DISRUPTS THE PRODUCTION OF FEAR BUT NOT THE INHIBITION OF FEAR CONDITIONED TO AN AUDITORY STIMULUS, Brain research, 813(2), 1998, pp. 274-282
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.