CRCNS: Long Term Reactivations in Cortex and Hippocampus

了解记忆是如何在大脑中编码和维持的，对于理解认知功能至关重要。与计算机不同的是，人类的记忆是在已经学过的内容的背景下不断巩固、重新巩固和整合的。这一过程被认为涉及睡眠期间大脑皮层和海马体之间的信息交换。研究人员将研究啮齿动物海马和内侧前额叶皮层（mPFC）中的小群细胞在学习后许多小时的睡眠期间短暂协同活动的能力。大鼠将参与旨在选择性激活其中一个或两个区域的学习任务。预计在任务后睡眠期间记录的活动将与任务期间相同细胞的活动相关联，其方式与任务的性质和学习的具体情况相一致。这种类型的再激活被认为是记忆巩固的基本机制。研究者开发了新的基于模糊聚类和信息几何的分析工具。初步数据表明，这两种结构的短时间再激活发生在不同的时间过程中，正如经常在理论基础上提出的那样。在这个项目中，研究人员将研究这种再激活是如何在很长时间尺度上跨两个相连的大脑区域（CA3-CA1, CA1-mPFC）协调的，以及单个神经元如何促进单个再激活事件。这些研究将深入了解成年啮齿动物的长期时间和空间动态再激活。这也将有助于更好地理解皮层和海马体中记忆巩固和再巩固的神经基础，以及记忆巩固与睡眠之间的关系。

Understanding how memory is encoded and maintained in our brain is paramount to understanding cognitive functions. Unlike in a computer, human memories are continuously consolidated, reconsolidated, and integrated within the context of what has already been learned. This process is thought to involve exchanges of information between the cortex and the hippocampus during sleep. The investigators will study the ability of small groups of cells in the rodent hippocampus and medial prefrontal cortex (mPFC) to become transiently co-active during sleep periods occurring many hours after learning has taken place. Rats will be engaged in learning tasks aimed at selectively activating one or both of these areas. It is expected that the activity recorded during post-task sleep will be correlated with the activity of the same cells during the task in a manner compatible with the nature of the task and the specifics of the learning. This type of reactivation is considered to be a basic mechanism for memory consolidation.The investigators have developed new analytical tools based on fuzzy clustering and information geometry. Preliminary data show that short episodes of reactivation occur with different time courses in these two structures, as is often proposed on theoretical grounds. In this project, the investigators will study how this reactivation is coordinated across two connected brain areas (CA3-CA1, CA1-mPFC) on very long time scales, and how single neurons contribute to single reactivating episodes.These studies will yield insights into the long-term temporal and spatial dynamics of reactivation in the adult rodent. They will also contribute to a better understanding of the neural basis of memory consolidation and reconsolidation in cortex and hippocampus, and the relationship between memory consolidation and sleep.