The Developing Engram – Imaging Memory Consolidation in Wakefulness and Sleep

正在发育的印迹——清醒和睡眠时的影像记忆巩固

• 批准号: 426865207
• 负责人: Professorin Dr. Monika Schönauer
• 金额: --
• 依托单位: Abteilung Neuropsychologie
• 依托单位国家: 德国
• 项目类别: Independent Junior Research Groups
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/426865207?language=en
• 关键词: Developing; Engram; Imaging; Memory; Consolidation

A question that has motivated research for decades is how continuous perception is transformed into lasting memories. New experiences leave lasting imprints in our brain, so-called “memory engrams.” But what determines whether an event will engender a neural engram and how long this physical record of the past will endure? Only if we can observe and manipulate the formation and development of memory traces in the brain can these questions be satisfactorily answered.After encoding, new memories have to be transformed to be stored for long term usage. During the course of this consolidation, the neural substrate supporting new memories is supposed to gradually shift from highly plastic hippocampal to slower-learning neocortical regions, a process that has been termed systems memory consolidation. This transformation is thought to be achieved by repeated training of neocortical memory networks, either by active rehearsal or by offline reactivation during sleep.Until recently, it has been difficult to study the covert processes that support memory consolidation. The advent of novel imaging methods and analysis approaches has now made it possible to locate and track memory engrams in both animals and humans. Contrary to the long-held belief that the neocortex is a slow learner, studies applying these tools have found that independent neocortical memory engrams are formed rapidly from the outset of learning.The overall goal of this proposal is to explore three factors that we think contribute to an accelerated redistribution of physical memory traces from the hippocampus to neocortex –retrieval, distributed practice, and sleep. We will apply novel diffusion-weighted imaging of learning induced plasticity in the human brain to test how and where memories are stored in the brain and to observe their redistribution over time. In particular, we will (1) assess how fast neocortical engrams emerge over repeated rehearsal, and whether they are formed at a temporal delay with respect to the hippocampal engram, (2) test whether rapidly formed neocortical engrams already carry specific information about the previous learning experience, (3) determine whether memory reactivation during sleep facilitates plasticity in the neocortex, and (4) whether beneficial effects of learning strategies such as learning by testing and distributed practice can be attributed to an acceleration of systems consolidation.Our results can help to critically revise model of memory consolidation, such that they make more accurate predictions about how the neocortex contributes to memory processing. Neocortical storage is critical for the long-term retention of new memories. Elucidating the factors that facilitate systems consolidation and neocortical plasticity is thus of the greatest relevance, not only for basic research, but also for clinical and educational settings.

几十年来，一个激发研究的问题是连续的感知如何转化为持久的记忆。新的经历会在我们的大脑中留下持久的印记，即所谓的“记忆印记”。但是，是什么决定了一个事件是否会产生一个神经印迹，以及这个过去的物理记录会持续多久？只有我们能够观察和操纵大脑中记忆痕迹的形成和发展，才能圆满地回答这些问题。在这个巩固过程中，支持新记忆的神经基质应该逐渐从高度可塑的海马转移到学习速度较慢的新皮层区域，这个过程被称为系统记忆巩固。这种转变被认为是通过对新皮层记忆网络的重复训练来实现的，无论是通过主动排练还是通过睡眠期间的离线重新激活，直到最近，一直很难研究支持记忆巩固的内隐过程。新的成像方法和分析方法的出现现在使得定位和跟踪动物和人类的记忆痕迹成为可能。长期以来，人们一直认为新皮层是一个缓慢的学习者，但运用这些工具进行的研究发现，独立的新皮层记忆痕迹从学习的一开始就迅速形成。这项研究的总体目标是探索我们认为有助于加速物理记忆痕迹从海马体到新皮层重新分配的三个因素--提取、分布式练习和睡眠。我们将应用新的弥散加权成像的学习诱导可塑性在人脑中测试如何和记忆存储在大脑中，并观察它们随时间的重新分布。特别是，我们将（1）评估在重复排练过程中新皮层记忆痕迹出现的速度，以及它们是否相对于海马记忆痕迹在时间上延迟形成，（2）测试快速形成的新皮层记忆痕迹是否已经携带了关于先前学习经验的特定信息，（3）确定睡眠期间记忆的重新激活是否促进了新皮层的可塑性，（4）通过测试学习和分布式练习等学习策略的有益效果是否可以归因于系统巩固的加速，我们的研究结果有助于批判性地修正记忆巩固模型，从而更准确地预测新皮层对记忆加工的贡献。新皮层存储对于新记忆的长期保留至关重要。因此，阐明促进系统巩固和新皮层可塑性的因素不仅对基础研究，而且对临床和教育环境都具有最大的相关性。