Episodic integration under stress

将独立的事件整合为情节是情节自传体记忆的一个基本过程。最近的研究表明，这种整合是由内侧前额叶皮层（mPFC）和海马介导的，海马的不同子区域代表不同程度的抽象情节。前额叶皮层和海马体对压力事件以及在压力遭遇时释放的激素和神经递质都非常敏感;压力被认为会降低这些区域的活动。压力是否会影响整合的事件，情节和神经机制参与了假定的压力效应是完全未知的，尽管这个问题的相当大的影响，也适用于上下文。我们假设，压力损害事件的整合，以情节和支持这种整合的神经过程，主要是在mPFC和海马。更具体地说，我们预测，压力将减少海马的失配反应和前额叶重组后，洞察到以前无关的事件的关系。此外，我们假设一个应激诱导的减少，情节关系的层次表示沿着海马长轴。这些压力引起的变化应该会导致一周后对编码事件及其关系的记忆受损。为了检验这些假设，健康志愿者将暴露于应激源或控制操作之前，他们完成，在MRI扫描仪，探测情节整合过程的任务。在任务完成后立即以及一周后测试成功的集成。除了它们对我们理解一般的情景-自传体记忆至关重要之外，这个项目的发现可能对压力相关的精神障碍有重要的影响，例如创伤后应激障碍，其中在高压力条件下编码的事件的分裂和碎片记忆非常常见。

The integration of separate events to episodes is a fundamental process for episodic-autobiographical memory. Recent research shows that this integration is critically mediated by the medial prefrontal cortex (mPFC) and hippocampus, with different subregions of the hippocampus representing episodes at a different degree of abstraction. Both the mPFC and the hippocampus are highly sensitive to stressful events and the hormones and neurotransmitters that are released in response to stressful encounters; stress is thought to reduce the activity in those areas. Whether stress affects the integration of events to episodes and which neural mechanisms are involved in the putative stress effect is completely unknown, despite the considerable implications of this issue, also for applied contexts. We hypothesize that stress impairs the integration of events to episodes and the neural processes supporting this integration, mainly in the mPFC and hippocampus. More specifically, we predict that stress will reduce the hippocampal mismatch-reaction and the hippocampal-prefrontal reorganization after insight into the relationship of previously unrelated episodes. Furthermore, we assume a stress-induced decrease in the hierarchical representation of episodic relationships along the hippocampal long axis. These stress-induced changes should result in impaired memory for the encoded episodes and their relationships after one week. In order to test these hypotheses, healthy volunteers will be exposed to a stressor or a control manipulation before they complete, in a MRI scanner, a task that probes episodic integration processes. The successful integration is tested immediately after the task as well as one week later. Beyond their crucial relevance for our understanding of episodic-autobiographical memory in general, the findings of this project might have important implications for stress-related mental disorders, such as post-traumatic stress disorder, in which disintegrated and fragmented memories for events encoded under high stress conditions are very common.