Astrocyte-neuron circuits underlying cortical mechanisms of learned behavior

星形胶质细胞是皮质中主要的非神经元细胞类型，并且越来越被认为是关键贡献者 神经元回路的发育、可塑性和功能。然而，它们如何参与学习的神经元 人们对行为和动态塑造底层皮层回路知之甚少。初级运动皮层 学习和执行自愿运动所必需的：获得有提示的、刻板的运动 在小鼠中，伴随着运动皮层神经元的突触重塑和协调的出现 运动相关的整体神经元活动。在这里，我们建议检查功能性星形胶质细胞机制 在运动皮层中，在运动学习过程中介导突触可塑性和神经元动力学。星形胶质细胞有 高度分支的精细过程，几乎接触皮层中的所有突触，并在其中调节突触 传输和可塑性的机制包括谷氨酸和 GABA 的摄取，主要通过 分别是转运蛋白 GLT1 和 GAT3。星形胶质细胞还响应并调节突触活动 其过程中时空异质的钙瞬变，称为微域。我们将检查 当小鼠学习前肢杠杆推动运动时，星形胶质细胞在塑造运动皮层回路中的作用，包括 使用一系列尖端方法来提示响应开始和可靠的运动轨迹：同步 星形胶质细胞和神经元体内高分辨率成像，星形胶质细胞的计算编码解码模型 和神经元活动、星形胶质细胞特异性基因表达分析以及新型星形胶质细胞光遗传学和 CRISPR 工具以及已建立的化学遗传学和病毒敲除方法。在我们初步的基础上 数据，证明星形胶质细胞微区反应和神经元的并行学习相关变化 在目标 1 中，我们将确定星形胶质细胞 GLT1 和 GAT3 的反应以及基因表达变化 学习过程中运动皮层的功能性星形胶质细胞钙特征及其与神经元活动的关系 和行为。我们假设星形胶质细胞在任务学习过程中塑造神经元可塑性，并具有相应的 它们的微域钙反应的可塑性，我们将通过计算来指定。在目标 2 中，我们将 确定星形胶质细胞钙信号传导对运动学习和神经元反应的影响。我们假设 钙瞬变的破坏可能会改变神经元群的出现和专家行为 通过改变星形胶质细胞转运机制的基因表达。在目标 3 中，我们将确定以下角色： 星形胶质细胞神经递质转运蛋白在运动皮层回路和学习中发挥作用。我们假设 通过 GLT1 破坏星形胶质细胞对兴奋性传递的调节，并通过 GAT3 破坏抑制性神经传递的星形细胞调节， 破坏星形胶质细胞的钙反应以及神经元回路的可塑性和行为。在一起，这些 研究将为星形胶质细胞参与星形胶质细胞的功能和可塑性提供机械的、计算的观点 皮层回路，揭示其对神经元反应和学习行为的特定任务贡献，并提供 理解它们在一系列大脑紊乱和疾病中的作用的基础。

Astrocytes are the major non-neuronal cell type in the cortex and are increasingly recognized as key contributors to the development, plasticity and function of neuronal circuits. Yet, how they participate with neurons in learned behavior and dynamically shape the underlying cortical circuits is poorly understood. The primary motor cortex is required for learning and executing voluntary movements: the acquisition of a cued, stereotyped, movement in mice is accompanied by synaptic remodeling of motor cortex neurons and the emergence of coordinated movement-related ensemble neuronal activity. Here, we propose to examine functional astrocyte mechanisms in motor cortex that mediate synaptic plasticity and neuronal dynamics during motor learning. Astrocytes have highly ramified fine processes that contact nearly all synapses in the cortex, where they modulate synaptic transmission and plasticity by mechanisms that include uptake of glutamate and GABA, primarily via the transporters GLT1 and GAT3 respectively. Astrocytes also respond to, as well as modulate, synaptic activity with spatiotemporally heterogeneous calcium transients in their processes, termed microdomains. We will examine the role of astrocytes in shaping motor cortex circuits as mice learn a forelimb lever push movement, including cued response onset and reliable movement trajectory, using a range of cutting-edge approaches: simultaneous high-resolution imaging of astrocytes and neurons in vivo, computational encoding-decoding models of astrocyte and neuronal activity, astrocyte-specific gene expression analyses, and novel astrocyte optogenetic and CRISPR tools alongside established chemogenetic and viral knockdown methods. Building on our preliminary data, which demonstrate parallel learning-related changes in astrocyte microdomain responses and neuronal responses, along with gene expression changes in astrocyte GLT1 and GAT3, in Aim 1 we will determine functional astrocyte calcium signatures in motor cortex during learning and their relationship to neuronal activity and behavior. We hypothesize that astrocytes shape neuronal plasticity during task learning with corresponding plasticity in their microdomain calcium responses, which we will specify computationally. In Aim 2, we will determine the effect of astrocyte calcium signaling on motor learning and neuronal responses. We hypothesize that disruption of calcium transients alters the emergence of neuronal ensembles and expert behavior, potentially by altering astrocyte gene expression of transporter mechanisms. In Aim 3, we will determine the role of astrocyte neurotransmitter transporter function in motor cortex circuits and learning. We hypothesize that disrupting astrocytic modulation of excitatory transmission via GLT1, and inhibitory neurotransmission via GAT3, disrupts astrocytic calcium responses together with neuronal circuit plasticity and behavior. Together, these studies will provide a mechanistic, computational view of astrocyte involvement in the function and plasticity of cortical circuits, reveal their task-specific contributions to neuronal responses and learned behavior, and provide the basis for understanding their role in a range of brain disorders and diseases.