PRETRAINING AND POSTTRAINING INFUSION OF N-METHYL-D-ASPARTATE RECEPTOR ANTAGONISTS INTO THE AMYGDALA IMPAIR MEMORY IN AN INHIBITORY AVOIDANCE TASK

Involvement of amygdaloid N-methyl-D-aspartate (NMDA) receptors in memory processes was investigated. Rats with cannulas implanted in the basolateral amygdala were trained on a 1 trial step-through inhibitory avoidance task and tested for 24-hr retention. Pretraining infusion of 2-amino-5-phosphonovaleric acid (APV) into the amygdala, but not striatum or hippocampus, produced a dose-dependent retention deficit, which was attenuated by immediate posttraining intra-amygdala infusion of NMDA. Posttraining APV infusion also caused a dose- and time-dependent retention deficit. Pretest APV infusion had no effect on performance in the retention test. Further, pre- or posttraining infusion of 50 mu g APV failed to affect acquisition and retention in the Morris water maze task. These findings suggest that amygdala NMDA receptors are normally activated by aversive training and play a critical role in memory formation for affective experience.