N-METHYL-D-ASPARTATE RECEPTORS IN THE BASOLATERAL AMYGDALA ARE REQUIRED FOR BOTH ACQUISITION AND EXPRESSION OF CONDITIONAL FEAR IN RATS

Three experiments examined the effects of intra-amygdaloid infusions o f an N-methyl-D-aspartate (NMDA) receptor antagonist, D,L-2-amino-5-ph osphonovalerate (APV), on contextual fear conditioning in rats. In Exp eriment 1, APV infusion into the basolateral amygdala (BLA), before tr aining, disrupted the acquisition of contextual fear. In Experiment 2, APV produced a disruption of both the acquisition and expression of c ontextual fear. This blockade of contextual fear was not state depende nt, not due to a shift in footshock sensitivity, and not the result of increased motor activity in APV-treated rats. In Experiment 3, fear c onditioning was not affected by a posttraining APV infusion into the B LA. These results indicate that NMDA receptors in the BLA are necessar y for both the acquisition and expression of Pavlovian fear conditioni ng to contextual cues in rats.