Sex differences in microglia-neuron-circuit interactions in adolescence

对神经元-胶质细胞相互作用的基本理解是将改变的免疫功能与破坏的神经元-胶质细胞相互作用联系起来的关键。 主要精神疾病中存在的回路和认知。小胶质细胞是大脑中的常驻免疫细胞， 在生理条件下，它们的主要功能之一是修改突触之间的连接。 神经元这些活动如何扩展到影响皮层回路中的高阶功能网络尚不清楚， 特别是在对认知功能至关重要的大脑区域，如前额叶皮层（PFC）。 关键可能在于神经回路同步如何刺激附近的小胶质细胞运动-即主动延伸 以及精细细胞过程的收缩-特别是，这种关系在整个过程中如何变化 青春期是PFC和高级认知发展的关键时期。此外，性别差异 在小胶质细胞功能的某些方面已经建立。阐明性别如何调节小胶质细胞在 PFC电路的发展是必不可少的，特别是考虑到青少年在脆弱性方面的巨大性别差异， 精神分裂症等精神疾病的发作。 本项目的目标是获得对神经胶质细胞-神经元-电路相互作用的基本了解， 哺乳动物前额叶皮层计划的方法（目标1）采用三维双光子显微镜 和单神经元光遗传学在清醒的小鼠内侧前额叶皮层（mPFC），以阐明如何结构 小胶质细胞的动力学由局部回路中的神经元活动和振荡同步性驱动。这将是 在从青春期前到成年早期的不同时间窗进行检查，并在男性和女性之间进行比较。 女性(Aim 2，3）为了测试小胶质细胞活性是否、如何以及何时对于建立成人神经细胞是必需的， mPFC功能，小胶质细胞将在青春期和早期的限制窗口期间被选择性地消除 成年期的药物治疗。然后在成年期，性别和生育期的具体影响， i）（目标2）mPFC（功能网络聚类，伽马）中时空电路动力学的发展 振荡，theta-gamma耦合）将使用双光子钙成像和致密电 记录和ii）（目标3）PFC依赖的认知将被评估与建立气味为基础的注意力 set-shifting任务 该项目采用最先进的光学技术来研究具有细胞行为的动物的脑功能， 水平精度。研究结果将确定小胶质细胞何时以及如何与发育中的神经元回路相互作用，以支持 生理条件下成人水平的认知功能。由于小胶质细胞可能是精神疾病的关键介质， 疾病相关的神经免疫功能障碍，该项目的基础科学见解，特别是由 性别和发育期分层的方法，可以改变对核心病理生理学的研究， 机制和基于电路的治疗。

A basic understanding of neuron-glia interactions is key to linking altered immune function to disrupted neural circuitry and cognition present in major psychiatric diseases. Microglia are a resident immune cell in the cerebral cortex, and one of their main functions under physiological conditions is to modify synaptic connections among neurons. How these activities extend to influence higher-order functional networks in cortical circuits is not clear, particularly in brain regions crucial for cognitive function, such as the prefrontal cortex (PFC). A key may lie in how neural circuit synchrony stimulates nearby microglial cell motility – i.e. active extension and retraction of fine cellular processes – and, specifically, in how this relationship changes throughout adolescence, a critical period for the development of PFC and higher cognition. Further, sex differences have been established in some aspects of microglial function. Clarifying how sex modulates the role of microglia in PFC circuit development is essential, especially given the dramatic sex differences in vulnerability to adolescent onset of psychiatric diseases such as schizophrenia. The goal of the current project is to obtain a basic understanding of glial-neuronal-circuit interactions in the mammalian prefrontal cortex. The planned approach (Aim 1) employs three-dimensional two-photon microscopy and single neuron optogenetics in awake mouse medial prefrontal cortex (mPFC) to elucidate how the structural dynamics of microglial cells are driven by neuronal activity and oscillatory synchrony in local circuits. This will be examined at distinct time windows from pre-adolescence into early adulthood and compared between males and females. (Aim 2,3) To test whether, how, and when microglia activity is necessary for the establishment of adult mPFC function, microglia will be selectively eliminated during restricted windows during adolescence and early adulthood using a pharmacological strategy. Then in adulthood, sex- and adolescent-period specific effects on the development of i) (Aim 2) spatiotemporal circuit dynamics in mPFC (functional network clustering, gamma oscillations, theta-gamma coupling) will be measured using two-photon calcium imaging and dense electrical recordings and ii) (Aim 3) PFC-dependent cognition will be assessed with an established odor-based attentional set-shifting task. This project employs state-of-the-art optical techniques to study brain function of behaving animals with cell- level precision. Results will identify when and how microglia interact with developing neuronal circuits to support adult-level cognitive function under physiological conditions. Since microglia may be a key mediator of psychiatric disease-relevant neuroimmune dysfunction, the basic science insights from this project, particularly afforded by a sex- and developmental-period stratified approach, could transform the search for core pathophysiological mechanisms and circuit-based treatments.