Astrocyte-neuron circuits underlying cortical mechanisms of learned behavior

星形胶质细胞是大脑皮层中主要的非神经元细胞类型，并且越来越多地被认为是关键的贡献者 神经回路的发育、可塑性和功能。然而，它们如何参与神经元的学习， 行为和动态形状的底层皮层电路是知之甚少。初级运动皮层 是学习和执行自愿运动所必需的：获得一个线索，定型， 在小鼠中，伴随着运动皮层神经元的突触重塑和协调的 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，其在运动学习期间介导突触可塑性和神经元动力学。星形胶质细胞具有 突触是一种高度分枝的精细突起，它与皮层中几乎所有的突触接触，在那里它们调节突触的活动。 传输和可塑性的机制，包括摄取谷氨酸和GABA，主要是通过 转运蛋白GLT 1和GAT 3。星形胶质细胞也响应并调节突触活动， 在它们的过程中，时空异质钙瞬变，称为微域。我们将研究 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 使用一系列先进的方法，提示响应启动和可靠的运动轨迹： 体内星形胶质细胞和神经元的高分辨率成像，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学和 CRISPR工具以及已建立的化学遗传学和病毒敲除方法。根据我们初步的 数据，这表明在星形胶质细胞微区反应和神经元的平行学习相关的变化， 沿着星形胶质细胞GLT 1和GAT 3基因表达的变化，我们将在目标1中确定 学习过程中运动皮层功能性星形胶质细胞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塑造了神经元的可塑性， 可塑性在他们的微域钙反应，我们将具体计算。在目标2中，我们 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 钙瞬变的破坏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基因表达的转运机制。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层回路和学习中的功能。我们假设 破坏通过GLT 1的兴奋性传递的星形胶质细胞调节和通过GAT 3的抑制性神经传递， 破坏星形胶质细胞钙反应以及神经元回路可塑性和行为。所有这些 研究将提供一个星形胶质细胞参与的功能和可塑性的机械，计算的观点， 皮层回路，揭示了它们对神经元反应和学习行为的任务特异性贡献，并提供了 了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.