LESIONS OF THE PERIRHINAL CORTEX INTERFERE WITH CONDITIONED EXCITATION BUT NOT WITH CONDITIONED INHIBITION OF FEAR

Posttraining lesions of the perirhinal cortex (Prh) have been shown to interfere with the expression of fear. This study assessed whether Pr h lesions would also disrupt the inhibition of fear as measured with c onditioned inhibition of fear-potentiated startle. Following light + s hock, noise --> light-no shock conditioned-inhibition training, rats w ere given Prh lesions. The lesions interfered with the expression of f ear-potentiated startle to the light. To assess whether conditioned in hibition was affected, the rats were given light + retraining without additional noise --> light - training. The noise-conditioned inhibitor retained its ability to inhibit fear-potentiated startle to the retra ined light. These results suggest that the areas of the Prh that are e ssential for the initial expression of conditioned fear are not import ant for the expression of conditioned inhibition of fear.