Memory under stress: focus on replay mechanisms

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Stressful events are typically much better remembered than mundane events. The same stressful events, however, may interfere with subsequent working memory and memory retrieval processes. We test here for the first time the hypothesis that these opposite effects on memory formation, working memory and retrieval are directly linked. Specifically, we assume that post-encoding replay processes after a stressful episode mediate both the superior memory for the episode itself and the impairment of following working memory and retrieval processes. To this aim, healthy participants will undergo a stressful encounter or a control event before they complete working memory and retrieval tests. Using fMRI and multivoxel-pattern analysis, memory replay will be assessed during a post-treatment rest period (compared to pre-treatment rest) as well as during the working memory and retrieval tasks. Memory for the stressful or control event will be tested one week later. We hypothesize that the memory enhancement for the stressful episode and the effect of the same episode on working memory and retrieval performance will be negatively correlated and linked to post-encoding replay processes. We further predict that the extent of replay and consequently the stress-related memory changes will be directly associated with the magnitude of the physiological stress response, in particular cortisol activity. The findings of this project may contribute to a new framework of stress effects on memory processes, reconciling seemingly opposite effects of stress on different memory processes, and may have relevant implications for educational contexts and stress-related mental disorders.