Defining Astrocyte Engram Ensembles During Memory Formation

总结 星形胶质细胞在脑功能中发挥着多种不可或缺的作用。作为"三方“的一个组成部分参加 突触“，估计单个星形胶质细胞接触海马体中多达100，000个神经元突触。值得注意的是， 研究已经确定了星形胶质细胞在海马回路中的基本功能，其中星形胶质细胞是海马回路所必需的。 调节突触可塑性，包括LTP，这是与学习和记忆相关的关键过程。最近的研究 已经表明，增强星形胶质细胞中的Gq信号可以促进LTP并增强急性记忆，同时损害 星形胶质细胞的功能抑制LTP和记忆，突出了星形胶质细胞在记忆依赖性 任务学习事件在离散的细胞集合中激发活动和可塑性。激活这些 通过学习和记忆回忆过程中重新激活的集合构成了记忆的物理基础， 称为记忆痕迹。尽管星形胶质细胞在学习和记忆过程中起着关键作用， 记忆痕迹的研究仅限于神经元的集合。本提案的目的是研究 星形胶质细胞印迹作为记忆基质的潜力，并了解海马神经元的性质和功能。 星形胶质细胞集合体 我们已经创建了许多小鼠品系和相关的AAV病毒工具，使我们能够标记和 在海马体的学习过程中操纵星形胶质细胞。对这些工具的初步研究表明， 我们可以在学习后标记星形胶质细胞的集合体， 回忆基于这些初步数据的强度和我们已经建立的相关工具，我们建议 以下具体目标。在特定的aim 1中，我们将在学习和表征星形胶质细胞群后标记它们。 它们是否表现出记忆印记的特性。在特定的aim 2中，我们将操纵预期的记忆印迹星形胶质细胞， 并确定它们是否编码记忆存储和回忆。在具体的aim3中，我们将描述 这些标记的星形胶质细胞印迹群体的细胞和分子特性。

Summary Astrocytes play diverse and indispensable roles in brain function. Participating as a component of the ‘tripartite synapse’, a single astrocyte is estimated to contact up to 100,000 neuronal synapses in the hippocampus. Notably, studies have identified essential functions of astrocytes in hippocampal circuits, where astrocytes are required for regulating synaptic plasticity including LTP, a key process associated with learning and memory. Recent studies have shown that enhancing Gq-signaling in astrocytes promotes LTP and enhances acute memory, while impairing astrocyte function suppresses LTP and memory, highlighting central roles for astrocytes in memory-dependent tasks. Learning events invoke activity and plasticity among a discrete ensemble of cells. Activation of these ensembles by learning and reactivated during memory recall constitute the physical substrate of memory and are referred to as engrams. Despite the critical involvement of astrocytes in learning and memory processes, the study of memory engrams has been limited exclusively to neuronal ensembles. The goal of this proposal is to study the potential of astrocyte engrams as a substrate of memory and to understand the nature and function of hippocampal astrocyte ensembles. We have created a host of mouse lines and associated AAV-viral tools the enable us to label and manipulate astrocytes during learning events in the hippocampus. Preliminary studies with these tools indicate that we can label ensembles of astrocytes after learning and that reactivation of these same astrocytes promotes memory recall. Based on the strength of these preliminary data and the associated tools we have built, we propose the following specific aims. In specific aim1, we will label astrocyte ensembles after learning and characterize whether they exhibit engram properties. In specific aim2, we will manipulate the prospective engram astrocyte populations and determine whether they encode memory storage and recall. In specific aim3, we will characterize the cellular and molecular properties of these labeled astrocyte engram populations.