Correlation of astrocyte Ca2+ microdomain activity with motor learning and neuronal function

这项研究的目标是了解星形胶质细胞（大脑中的一种胶质细胞）如何与运动皮层神经元一起调节运动学习。先前的研究表明，当动物成为刻板动作的专家时，一个稳定的神经元集合就会出现。研究还表明，星形胶质细胞钙信号，特别是在突触周围精细过程的微域，对神经元活动作出反应并与之相关。星形胶质细胞微结构域被认为反映突触活动，进而影响突触功能。我们假设运动皮层星形胶质细胞Ca2+活性的稳定模式在小鼠的刻板运动习得过程中发展，与神经元激活和学习相关，并与细胞内Ca2+一起，是学习的潜在原因。我们将利用一系列尖端技术来验证这一假设，以及杠杆推动任务，这是一种运动学习范式，其特点是联想学习和刻板运动的习得。我们将利用在星形胶质细胞中表达膜结合遗传编码钙指标的转基因小鼠，结合高分辨率双光子成像，在动物学习执行任务时长期成像钙微域活动。这些实验将确定是否独特的微域激活模式出现与运动学习。然后，我们提出通过在兴奋性神经元中表达光激活的盐紫红质或通道紫红质，分别通过光遗传学破坏运动皮层中的神经元信号，以灭活或激活神经元活动，以确定微域星形胶质细胞钙活性模式是否随着运动学习而被破坏。最后，我们将使用专门由设计药物激活的设计受体（DREADDs）破坏星形胶质细胞内的钙信号，以确定当星形胶质细胞钙信号（包括微结构域）被破坏时，是否对运动学习有影响。总之，这些研究将不仅确定星形胶质细胞的“签名”编码的微域与运动学习有关，但也提供机制洞察这种活动结构是如何通过神经元活化调节，以及如何，与细胞内Ca2+信号，它影响运动学习。鉴于星形胶质细胞功能障碍与许多涉及异常神经元回路功能的神经系统疾病有关，包括精神分裂症、抑郁症和癫痫，推进我们对星形胶质细胞-神经元相互作用的理解将填补知识的关键空白，并有可能为新的治疗方法做出贡献。

The goal of the proposed research is to understand how astrocytes, a type of glial cell in the brain, work together with motor cortex neurons to mediate motor learning. Previous studies have shown that a stable ensemble of neurons emerges as an animal becomes expert at a stereotyped movement. It has also been shown that astrocyte calcium signaling, particularly in microdomains of the fine processes surrounding synapses, responds to and correlates with neuronal activity. Astrocyte microdomains are considered to reflect synaptic activity and in turn, influence synaptic function. We hypothesize that a stable pattern of motor cortex astrocyte Ca2+ activity in microdomains develops during acquisition of a stereotyped motor movement in mice, is correlated with neuronal activation and learning, and together with intracellular Ca2+, is potentially causal for learning. We will utilize a range of cutting edge techniques to test this hypothesis, as well as a lever push task, which is a motor learning paradigm that features both associative learning and acquisition of a stereotyped motor movement. We will utilize transgenic mice expressing membrane-bound genetically encoded calcium indicators in astrocytes, combined with high-resolution two-photon imaging, to chronically image calcium microdomain activity as the animal learns to perform the task. These experiments will determine whether unique microdomain activation patterns emerge with motor learning. We then propose to optogenetically disrupt neuronal signaling in the motor cortex using expression of light-activated halorhodopsin or channelrhodopsin in excitatory neurons to inactivate or activate neuronal activity, respectively, in order to determine if patterns of astrocyte calcium activity in microdomains are disrupted along with motor learning. Finally, we will disrupt intracellular calcium signaling in astrocytes using designer receptors exclusively activated by designer drugs (DREADDs) to determine whether there is an effect on motor learning when astrocyte calcium signals, including microdomains, are disrupted. Together, these studies will not only identify an astrocyte “signature” encoded by microdomains which is associated with motor learning, but also provide mechanistic insight into how this activity structure is regulated by neuronal activation, and how, alongside intracellular Ca2+ signaling, it influences motor learning. Given that astrocyte dysfunction has been implicated in a number of neurological conditions that involve aberrant neuronal circuit function, including schizophrenia, depression, and epilepsy, advancing our understanding of astrocyte-neuron interactions will fill critical gaps in knowledge and potentially contribute to novel therapeutics.