THE EFFECTS OF INTRAAMYGDALA INFUSION OF THE AMPA RECEPTOR ANTAGONISTCNQX ON RETENTION PERFORMANCE FOLLOWING AVERSIVE TRAINING

The aim of these experiments was to determine whether impaired retenti on performance in aversively motivated tasks, induced by blockade of a mygdala AMPA receptors, is due to influences on mechanisms underlying memory retrieval or to other influences on performance. Rats received either footshock escape training (1 or 10 trials), or no foot shock, i n a two-compartment straight alley and bilateral intra-amygdala infusi ons of the AMPA receptor antagonist CNQX (0.5 mu g) were subsequently administered prior to inhibitory avoidance retention testing 8 days la ter. The CNQX impaired, but did not block, inhibitory avoidance retent ion performance as indicated by the initial latencies to enter the sho ck compartment. The animals were then retained in the alley until they remained in the starting compartment for 100 consecutive s and entrie s into the shock compartment were recorded as errors. In both the cont rols and CNQX-treated groups, increases in amount of original training resulted in fewer errors, indicating memory for the escape training. Furthermore, regardless of the amount of original training (i.e., 0, 1 , or 10 trials), CNQX-treated groups made more errors. Other experimen ts examined intra-amygdala CNQX effects on reactivity to footshock, lo comotor activity, and anxiety. CNQX decreased reactivity to footshock, blocked shock induced decreases in locomotor activity, and had an anx iolytic effect in an elevated plus maze comparable to that induced by midazolam (0.5 mu g). These findings suggest that intra-amygdala infus ions of CNQX prior to retention testing affect inhibitory avoidance re tention performance following aversive training by altering locomotor activity, reducing sensitivity to footshock, and reducing anxiety. The implications of these findings for hypotheses concerning amygdala fun ction in aversively motivated learning and memory is discussed. (C) 19 96 Academic Press, Inc.