Delineation of astrocyte microdomain calcium events during cortical activity

星形胶质细胞是一种脑胶质细胞，对正常的神经元功能至关重要。众所周知，它们在许多方面支持神经元：通过提供能量、清除废物和维持适当的神经元活动环境。也有证据表明星形胶质细胞感知神经元活动并主动释放分子来改变神经元功能。我的研究项目的长期目标是确定神经元-星形胶质细胞通讯的本质，并确定星形胶质细胞如何改变感觉回路中的神经元活动，从而影响皮层信息处理。神经元活动引起星形胶质细胞钙的局部增加，称为“微域钙事件”（MCEs）。这些mce已成为星形胶质细胞活性的重要生物标志物，因为它们是星形胶质细胞向神经元传递信号所必需的。因此，为了了解星形胶质细胞的功能作用，充分表征星形胶质细胞mce是很重要的。我的HQP将使用新颖的遗传工具和先进的体内双光子显微镜，在清醒的动物体内进行体感刺激，研究完整电路内星形胶质细胞mce和附近神经元。首先，我们将把皮层星形胶质细胞mce与附近的神经元活动联系起来，以确定诱导星形胶质细胞mce的神经元类型（兴奋性与抑制性）和亚细胞区室（体细胞与树突），特别是在生理须刺激期间。接下来，我们将研究在感觉剥夺范式下神经元重组过程中星形胶质细胞MCE的募集，这将为星形胶质细胞如何响应并可能调节神经元群体的变化提供见解。最后，我的初步数据表明，星形胶质细胞n -甲基- d -天冬氨酸受体是由兴奋性谷氨酸激活的嗜离子受体，在星形胶质细胞mce中发挥重要作用，并影响附近神经元的活动。我的团队将进一步研究这些星形胶质细胞受体的功能作用，包括它们如何影响兴奋性或抑制性神经元群，并最终影响小鼠的感觉知觉。总的来说，这些结果将提供皮质星形胶质细胞mce的几个未知方面的重要特征，包括识别引起这些星形胶质细胞信号的特定机制和神经元贡献，以及相反，这些局部信号对附近突触传递的影响。这将推动当前星形胶质细胞的概念，为理解神经元-星形胶质细胞的通讯以及星形胶质细胞如何整合到脑回路中提供更坚实的基础。这与我们对突触级微电路的理解直接相关，但对大规模脑系统连接也有更广泛的影响。该研究项目创造的培训环境将在这个5年周期内为至少两名研究生和十名本科生提供尖端技术和可转移技能。

Astrocytes, a type of brain glial cell, are important for normal neuronal function. They are known to support neurons in many ways: by supplying energy, removing wastes, and maintaining an environment for proper neuronal activity. There is also evidence that astrocytes sense neuronal activity and actively release molecules to change neuronal function. The long-term goal of my research program is to determine the nature of neuron-astrocyte communication and define how astrocytes can change neuronal activity within sensory circuits to influence cortical information processing. Neuronal activity causes local increases in astrocyte calcium, termed "microdomain calcium events" (MCEs). These MCEs have become an important biomarker of astrocyte activity, since they are necessary for astrocyte signaling back to neurons. Therefore, in order to understand the functional roles of astrocytes, it is important that we fully characterize astrocyte MCEs. My HQP will use novel genetic tools and cutting-edge in vivo two-photon microscopy in awake animals during somatosensory stimulation to study astrocyte MCEs and nearby neurons within intact circuits. First, we will correlate cortical astrocyte MCEs with nearby neuronal activity to determine the neuronal type (excitatory vs. inhibitory) and subcellular compartment (soma vs. dendrite) that induces astrocyte MCEs, particularly during physiological whisker stimulation. Next, we will examine astrocyte MCE recruitment during neuronal reorganization during a sensory deprivation paradigm, which will provide insight into how astrocytes respond to and possibly tune neuronal population changes. Finally, my preliminary data shows that astrocyte N-methyl-D-aspartate receptors, ionotropic receptors activated by excitatory glutamate, play an important role in astrocyte MCEs and affect nearby neuronal activity. My group will further investigate the functional role of these astrocyte receptors, including in how they influence excitatory or inhibitory neuronal populations and ultimately affect mouse sensory perception.  Overall, results will provide an important characterization of several unknown aspects of cortical astrocyte MCEs, including identification of specific mechanisms and neuronal contributions that evoke these astrocyte signals and conversely, the influence these localized signals have on nearby synaptic transmission. This will advance current concepts of astrocytes in directions that provide a more solid foundation for understanding neuron-astrocyte communication and how astrocytes are integrated into brain circuits. This is directly relevant for our understanding of synaptic level microcircuits but also has broader implications for large-scale brain system connectivity. The training environment created by this research program will provide cutting-edge technical and transferable skills for a minimum of two graduate students and ten undergraduate students in this 5-year cycle.