CRCNS: Long Term Reactivations in Cortex and Hippocampus

了解记忆是如何在我们的大脑中编码和维持的，对于了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到的东西的背景下不断巩固、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体和内侧前额叶皮质(MPFC)中的小细胞群在学习发生数小时后的睡眠期间瞬时协同活动的能力。老鼠将参与学习任务，目的是选择性地激活这两个区域中的一个或两个。预计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。这种类型的重新激活被认为是记忆巩固的基本机制。研究人员开发了基于模糊聚类和信息几何的新分析工具。初步数据显示，在这两种结构中，重新激活的短插曲发生在不同的时间进程中，这一点经常被理论上提出。在这个项目中，研究人员将研究这种重新激活是如何在非常长的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对单个重新激活事件做出贡献。这些研究将对成年啮齿动物重新激活的长期时间和空间动力学产生洞察力。他们还将有助于更好地理解记忆巩固的神经基础，以及记忆巩固和睡眠之间的关系。

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.