Delineation of astrocyte microdomain calcium events during cortical activity

星形胶质细胞是脑神经胶质细胞的一种，对正常神经元功能具有重要作用。众所周知，它们以多种方式支持神经元：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。我的研究计划的长期目标是确定神经元与星形胶质细胞交流的性质，并确定星形胶质细胞如何改变感觉回路中的神经元活动，以影响皮质信息处理。神经元活动引起星形胶质细胞局部钙升高，称为微域钙事件(MCEs)。这些MCEs已经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回传信号所必需的。因此，为了了解星形胶质细胞的功能作用，我们必须充分了解星形胶质细胞MCEs的特征。 我的HQP将使用新的遗传工具和在体感刺激期间清醒动物体内尖端的双光子显微镜来研究星形胶质细胞MCE和附近完整电路中的神经元。首先，我们将大脑皮质星形胶质细胞MCEs与邻近神经元的活动相关联，以确定诱导星形胶质细胞MCEs的神经元类型(兴奋性与抑制性)和亚细胞室(胞体与树突)，特别是在生理胡须刺激期间。接下来，我们将研究感觉剥夺范式中神经元重组过程中星形胶质细胞MCE的重新募集，这将提供对星形胶质细胞如何响应并可能调整神经元数量变化的洞察。最后，我的初步数据显示，星形胶质细胞N-甲基-D-天冬氨酸受体，兴奋性谷氨酸激活的离子受体，在星形胶质细胞MCEs中发挥重要作用，并影响邻近神经元的活动。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体，并最终影响小鼠的感官知觉。 总体而言，这些结果将为皮质星形胶质细胞MCEs的几个未知方面提供重要的表征，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，以及反过来，这些局部信号对附近突触传递的影响。这将推动当前关于星形胶质细胞的概念，为理解神经元与星形胶质细胞的交流以及星形胶质细胞如何整合到大脑回路提供更坚实的基础。这与我们对突触水平微电路的理解直接相关，但也对大规模大脑系统的连接具有更广泛的影响。该研究计划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移植技能。

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.