Characterization of long-term memory formation for experimental, real-life-like stressful events on the behavioral and neural level - from encoding, over early to ling-term consolidation

我们对生活片段的记忆最初是生动而详细的，但它们中的大多数都变成了更像要点甚至是图式的表征。然而，我们对压力经历的长期记忆似乎特别准确和详细。但人类对创伤性记忆的回顾性研究表明，这些记忆只是被认为更详细，而不是客观上被更好地记住。巩固理论认为，从详细记忆到概要记忆和图式记忆的转变反映在海马轴和皮层记忆检索的转移中。目前还缺乏对人类进行足够长时间的纵向研究，以严格检验这些理论。关于压力事件的长期记忆，唯一的动物研究表明，它们停留的时间更长，而且依赖于海马体，这与人类的回顾性研究相反。因此，第一个资助期的目标是表征中性和压力事件的长期记忆形成，从编码到行为和神经水平的早期到长期巩固。研究人员对92名参与者（46名对照）进行了长达2.5小时的标准化的现实生活压力和中性事件的记忆追踪，从编码时间到随后的8个月，使用了行为测量、眼动追踪、生物识别、睡眠测谎和功能磁共振成像。初步结果显示，人们的记忆向不那么详细、更多错误的记忆转变。这与向前额叶和颞叶皮层检索的转变同时发生，表明系统巩固显然已经开始。应激事件的记忆形成显示了假设的特殊性，开始于编码期间的注意力缩小，随后晚上的长时间慢波睡眠（与早期巩固有关），第二天回忆时杏仁核活动更大，8个月后也有更强的前额叶参与。第二天，压力大的参与者回忆起更多的核心和内省细节。即使在8个月后，内省细节的差异仍然存在——与更高的主观细节一致。综上所述，我们的初步结果清楚地表明，记忆的长期巩固和转化已经开始，但与此同时，这些过程尚未完成。在更长的时间内描述这些记忆的巩固轨迹，将对当前的巩固理论和对我们对压力事件的记忆的复杂特征的理解产生极大的兴趣。因此，拟议项目的目标是建立在这个独特的数据集上，并在编码后对参与者的记忆进行长达3年的跟踪。我们建议不仅在行为和神经水平上表征记忆，而且探索系统巩固是否可以逆转，以及在多大程度上可以使用fil恢复不可访问的细节。

The memories for the episodes of our lives are initially vivid and detailed but most of them are transformed to more gist-like or even schematic representations. Our long-term memories for stressful experiences however, seem to stay particularly accurate and detailed. But human retrospective studies on traumatic memories suggest that those are only perceived as more detailed but not objectively better remembered. Consolidation theory propose that the transformation from detailed to gist-like and schematic memories is reflected in a shift along the hippocampal axis and to cortical memory retrieval. Longitudinal studies in humans over sufficiently long time periods to rigorously test these theories are currently missing. With respect to long-term memory for stressful events the only animal study suggests that they stay longer detailed and hippocampus dependent, contrary to the retrospective studies in humans. The goal of the first funding period was therefore to characterize long-term memory formation for neutral and stressful episodes, from encoding, over early- to long-term consolidation on the behavioural and neural level. Memory for a 2.5 hours long series of standardized real-life stressful and neutral episodes was tracked in 92 participants (46 controls) from time of encoding and over the 8 months following using behavioural measures, eye-tracking, biometrics, sleep polygraphy, and fMRI. The preliminary results show a transformation to less detailed and more false memories. This goes along with a shift towards prefrontal and temporal cortical retrieval indicating that systems consolidation clearly has begun. Memory formation for stressful episodes shows the hypothesized particularities starting with attentional narrowing during encoding, prolonged slow wave sleep – implicated in early-consolidation – in the subsequent night, greater amygdala activity during recall the next day and stronger precuneal involvement also after 8 months. On the next day, stressed participants recall more central and introspective details. Even after 8 months, the difference in introspective details still exists – consistent with higher subjective detailedness. Taken together, our preliminary results show clearly that long-term consolidation and transformation of the memories have begun but at the same time that these processes are not yet completed. It would be of great interest for current consolidation theories and for the understanding of the complex characteristics of our memories for stressful events to characterize the consolidation trajectories of these memories for an even longer time. The goal of the proposed project is therefore to build on this unique data set and follow-up the participants’ memories for up to 3 years after encoding. We propose not only to characterize the memories on the behavioural and neural level but also explore whether systems consolidation can be reversed and to what degree by then inaccessible details can be restored using fil.