Stress-induced Memory Enhancement for Inhibitory Fear Conditioning in Rats

Publication Title


Publication Date


Document Type





stress, memory enhancement, inhibitory fear conditioning




The retroactive effects of stress on memory have not received a great deal of empirical attention; however, the research that has been conducted has reported both positive and negative effects of stress on memorial processes. The goal of this study was to examine the effects of a naturalistic stressor—an intense bout of exercise—on memory for inhibitory fear conditioning in rats. Experiment 1 investigated the retroactive effect of a stressful swim treatment on memory for passive avoidance (PA) training. Rats that received an immediate posttraining swim treatment demonstrated a significant enhancement in performance when tested for retention 24 h later. Furthermore, the enhancing effect of the swim treatment was time dependent: Rats receiving the swim treatment 15 min after PA training no longer exhibited reliably better scores than did rats not receiving the swim treatment. Experiment 2 used preexposures to control for the possibility that the swim treatment was enhancing avoidance scores by acting as a punisher rather than a memory modulator. Results indicate that both the group that was preexposed and the group that was not preexposed showed reliably higher scores than did a group of animals receiving only PA training, thus replicating Experiment 1. Furthermore, the results of Experiment 2 suggest that swimming was not simply acting as a punishing agent, since preexposures to the treatment did not attenuate its memory-enhancing properties. The possible role of stress-related hormones on memory processes is considered.