Mean (±SEM) latency (in seconds) to cross to the black side of the black–white shuttle box for both groups in experiment 2. Longer latency scores for the stress group that was stressed 48 h prior to training replicate the stress-induced impairment of extinction. Decreased latency scores for the group injected with cycloheximide immediately after stress (RA/stress) compared with the increased scores of the stress group replicate retrograde amnesia for the stress memory. Longer latencies exhibited by the group that received a brief stress exposure (re-expose) demonstrate the recovery of the forgotten stress memory. The brief stress group showing less avoidance demonstrates that a 5-min restraint stress session before training was not sufficient to impair extinction retrieval.
