Stress and schema-based inference learning

现有的知识网络（图式）提供了影响记忆形成和检索的组织结构。特别是已有的知识便于对相关信息进行编码。这种所谓的基于图式的记忆是特别有趣的，因为它提供了对新信息和现有记忆整合的见解。来自啮齿动物和人类研究的越来越多的证据表明，内侧前额叶皮层是图式记忆的关键位点。众所周知，有压力的遭遇会影响记忆过程，而内侧前额叶皮层是大脑中对压力最敏感的区域之一。然而，压力是否会改变基于图式的记忆，从而改变现有记忆和新信息的整合，目前尚不清楚。本项目将解决这个问题，并研究压力是否以及如何影响基于图式的记忆。为此，健康的参与者将首先获得有关等级结构的知识。24小时后，他们将经历一个社会心理压力源（或控制操作），然后获得两个新的等级：一个是完全新的等级，另一个是与前一天学到的等级有关的等级。为了检查压力对图式记忆的影响所涉及的大脑过程，第二天的行为测试将在扫描仪中进行。我们预测，压力会降低先验知识对相关信息编码的有益作用。在神经水平上，我们预计假定的应激效应将与内侧前额叶皮层的活动减少以及该区域与内侧颞叶和顶叶区域的连通性改变相平行。这个项目的发现不仅将增强我们对压力如何塑造记忆过程的理解，而且可能对教育和临床环境有相当大的影响。

Existing networks of knowledge (schemas) provide organizing structures that influence memory formation and retrieval. In particular, existing knowledge facilitates the encoding of related information. This so-called schema-based memory is of particular interest as it provides insights into the integration of new information and existing memories. Converging lines of evidence from rodent and human studies identified the medial prefrontal cortex as a critical locus of schema-based memory. Stressful encounters are known to affect memory processes and the medial prefrontal cortex is among the brain areas that are most sensitive to stress. However, whether stress may change schema-based memory and thus the integration of existing memories and new information is unknown. The present project will address this question and examine if and how stress influences schema-based memory. To this end, healthy participants will first acquire knowledge about a hierarchical structure. Twenty-four hours later, they will undergo a psychosocial stressor (or a control manipulation) before they acquire a two new hierarchies: one that is entirely novel and one that is related to the hierarchy learned on the previous day. In order to examine the brain processes involved in the impact of stress on schema-based memory, behavioral testing on this second day will take place in the scanner. We predict that stress will reduce the beneficial effect of prior knowledge on the encoding of related information. At the neural level, we expect that the putative stress effect will be paralleled by reduced activity of the medial prefrontal cortex and altered connectivity of this area with medial-temporal and parietal areas. The findings of this project will not only enhance our understanding of how stress shapes memory processes but may also have considerable implications for educational and clinical settings.