Memory under stress: focus on replay mechanisms

压力事件通常比平凡事件更容易被记住。然而，同样的压力事件可能会干扰随后的工作记忆和记忆检索过程。我们在这里首次验证了这样一个假设，即这些对记忆形成、工作记忆和检索的相反影响是直接相关的。具体来说，我们假设应激事件后的编码后重放过程既介导了对应激事件本身的优越记忆，也介导了随后的工作记忆和检索过程的损害。为了达到这个目的，健康的参与者在完成工作记忆和检索测试之前会经历一次有压力的遭遇或控制事件。使用功能磁共振成像和多体素模式分析，将在治疗后休息期间（与治疗前休息期间相比）以及在工作记忆和检索任务期间评估记忆重播。对压力或控制事件的记忆将在一周后测试。我们假设应激事件的记忆增强与应激事件对工作记忆和检索性能的影响呈负相关，并与编码后回放过程相关。我们进一步预测，重放的程度以及与压力相关的记忆变化将与生理应激反应的大小直接相关，特别是皮质醇活动。本项目的研究结果可能有助于建立压力对记忆过程影响的新框架，调和压力对不同记忆过程的看似相反的影响，并可能对教育背景和压力相关的精神障碍有相关的启示。

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.