Effect of arousal conditions during reinstatement treatment upon learned fear in young rats.

The role of shock and epinephrine-induced arousal in the reinstatement of learned fear was investigated in young rats. Groups of 21-day-old rats received classical fear conditioning to the black compartment of a black/white avoidance box. One week later each rat received one of a number of reinstatement conditions consisting of exposure to the apparatus cues, non-contingent foot shock, or exogenous epinephrine injections, alone or in combination. Subjects were tested for retention of spatial avoidance behavior 1 week following reinstatement. Reinstatement with epinephrine and exposure to the training contextual cues, non-contingent foot shock followed by cue exposure, and non-contingent foot shock alone were all found to be as effective as shock administered in conjunction with the cues (the same conditions as those prevailing during training). Cue exposure alone and epinephrine injections without the training cues were ineffective reinstating agents.