THE CENTRAL AMYGDALA IS INVOLVED IN CONDITIONING BUT NOT IN RETENTION OF ACTIVE AND PASSIVE SHOCK AVOIDANCE IN MALE-RATS

The present study was designed to further characterize the involvement of the central amygdaloid nucleus (CEA) in the conditioning and the retention of both active and passive stress-related behaviors. Active shock avoidance was investigated in a shuttle-box. CEA-lesioned and sham-operated animals received 30 trials on 2 consecutive days. During the first day of conditioning, the CEA-lesioned animals failed to learn to avoid, but on the second day these rats showed avoidance behavior that was comparable to the sham-lesioned ones. When lesioned animals received a total of 60 trials on 1 day, they failed to show avoidance, suggesting deficits in acquisition performance but presence of latent learning following CEA lesioning. However, the retention response, which was studied by lesioning the CEA between a 2-day avoidance training and a retention test, was unaffected. Stress-related learning was also studied in a test of passive avoidance of a previously received single, inescapable electric footshock. When the lesion was placed before the single learning trial, the retention of the response was absent. However, CEA-lesioning after the learning trial revealed no differences between the CEA-lesioned and sham-lesioned animals. In conclusion, these results demonstrate that the CEA is involved in the conditioning rather than retention of both active and passive shock avoidance responses. © 1993 Academic Press, Inc.