Astrocyte-neuron circuits underlying cortical mechanisms of learned behavior

星形胶质细胞是大脑皮质中主要的非神经细胞类型，越来越被认为是关键贡献者。 对神经元回路的发育、可塑性和功能的影响。然而，它们是如何与神经元一起参与学习的 行为和动态塑造潜在的大脑皮层回路还知之甚少。初级运动皮质 是学习和执行自愿动作所必需的：获得一个暗示的、刻板的、 在小鼠中伴有突触重塑的运动皮质神经元的出现和协调 与运动相关的整体神经元活动。在这里，我们建议研究星形胶质细胞的功能机制。 在运动学习过程中调节突触可塑性和神经元动力学的运动皮质。星形胶质细胞有 高度分叉的精细突起与皮质中几乎所有的突触接触，在那里它们调节突触 传递和可塑性的机制，包括摄取谷氨酸和GABA，主要是通过 转运蛋白GLT1和GAT3。星形胶质细胞也对突触活动作出反应，并通过 在其过程中的时空不均匀的钙瞬变，被称为微域。我们将研究 在小鼠学习前肢推力运动时，星形胶质细胞在形成运动皮质回路中的作用，包括 提示响应开始和可靠的移动轨迹，使用一系列尖端方法：同时 星形胶质细胞和神经元的体内高分辨率成像，星形胶质细胞的计算编码-解码模型 和神经元活性，星形胶质细胞特异性基因表达分析，以及新的星形胶质细胞光遗传和 CRISPR工具与成熟的化学遗传和病毒敲除方法相结合。在我们初步的基础上 数据，显示与学习相关的星形胶质细胞微域反应和神经元的平行变化 反应，以及星形胶质细胞GLT1和GAT3基因表达的变化，在目标1中，我们将确定 学习过程中运动皮质星形胶质细胞功能钙信号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形成神经元可塑性，并相应地 他们的微域钙反应的可塑性，我们将通过计算来具体说明。在目标2中，我们将 确定星形胶质细胞钙信号对运动学习和神经元反应的影响。我们假设 钙瞬变的这种干扰潜在地改变了神经元集合和专家行为的出现 通过改变星形胶质细胞转运蛋白的基因表达机制。在目标3中，我们将确定 星形胶质细胞神经递质转运体在运动皮质回路和学习中的作用。我们假设 通过GLT1干扰星形胶质细胞对兴奋性传递的调节，通过GAT3抑制神经传递， 破坏星形细胞的钙反应以及神经元回路的可塑性和行为。加在一起，这些 研究将提供星形胶质细胞参与脑胶质细胞功能和可塑性的机制和计算观点。 大脑皮层回路，揭示它们对神经元反应和习得行为的特定任务贡献，并提供 这是了解它们在一系列大脑紊乱和疾病中所起作用的基础。

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.