A Functional Taxonomy of Cortical Astrocytes

大脑皮层星形胶质细胞的功能分类 绝大多数神经回路研究忽略了对非神经元的研究 但为了真正了解神经回路的功能，我们需要监测 并操纵多种细胞类型的活动。我们对星形胶质细胞信号的理解是多年的 落后于神经元，因为在很大程度上，缺乏适当的工具来处理这些 无声的电池。我们不知道星形胶质细胞对细胞外信号有什么反应，也不知道星形胶质细胞是如何反应的 它们对电路功能有贡献。这在一定程度上是由于缺乏复制 体内可能的突触前活动的广度，即神经递质的释放。海流 该方案解决了我们对星形胶质细胞在神经回路功能和 利用光激活工具的力量来解决这些问题。我们建议应用一套 光化学工具，允许时空精确和生理相关的释放 皮质环路中星形胶质细胞和神经元的神经递质。 在目标1中，我们将检验星形胶质细胞对突触做出尖锐反应的假设。 释放兴奋性和抑制性突触活动，具有不同的和可预测的活动。我们 将在星形胶质细胞中同时使用双光子光化学去除和钙成像 以测试它们对谷氨酸和GABA能突触事件的生理反应， 并揭示支配这些反应的分子机制的异质性。我们会 使用这些光化学技术在体内激活星形胶质细胞，在Aim 2中，从基因上 星形胶质细胞特异性兴奋性和抑制性受体在活体成像和 电生理学，以确定导致下行皮质状态的星形细胞信号 轮班。在目标3中，我们将验证新的光化学工具来模拟释放 大脑皮层回路中的神经调节剂，测试它们在神经元和星形胶质细胞中的功能。使用 有了这些工具，我们将能够探测星形胶质细胞对 在电路中作出反应。

A Functional Taxonomy of Cortical Astrocytes The vast majority of neural circuit studies neglect to take into account the non-neuronal cells in the brain, but in order to truly appreciate neural circuit function, we will need to monitor and manipulate activity in many cell types. Our understanding of astrocyte signaling is years behind that of neurons, because the appropriate tools have been lacking for these largely electrically silent cells. We don't know what extracellular signals astrocytes respond to, nor how they contribute to circuit function. This is due, in part, to the lack of methods that replicate the breadth of possible presynaptic activity in vivo, i.e. the release of neurotransmitter. The current proposal addresses gaps in our understanding of astrocytes in neural circuit function and harnesses the power of light-activatable tools to tackle them. We propose to apply a suite of optochemical tools that allow spatiotemporally precise and physiologically relevant release of neurotransmitter to astrocytes and neurons in cortical circuits. In Aim 1, we will test the hypothesis that astrocytes response acutely to the synaptic release of excitatory and inhibitory synaptic activity with differential and predictable activity. We will use simultaneous two-photon optochemical uncaging and calcium imaging in astrocyte branches to test their physiological response to glutamatergic and GABAergic synaptic events, and uncover the heterogeneity of molecular mechanisms that govern these responses. We will activate astrocytes in vivo using these optochemical techniques, and in Aim 2, genetically silence astrocyte-specific excitatory and inhibitory receptors during in vivo imaging and electrophysiology to determine the astrocytic signals that lead to downstream cortical state shifts. In Aim 3, we will validate novel optochemical tools to mimic the release of neuromodulators in the cortical circuit, testing their function in neurons and astrocytes. With these tools in hand, we will be able to probe the repertoire of signals to which astrocytes respond in the circuit.