Sex differences in microglia-neuron-circuit interactions in adolescence

对神经元-神经胶质细胞相互作用的基本了解是将免疫功能改变与神经功能紊乱联系起来的关键 回路和认知存在于主要精神疾病中。小胶质细胞是大脑中的一种常驻免疫细胞。 在生理条件下，它们的主要功能之一是改变 神经元。这些活动如何扩展到影响皮质回路中的高阶功能网络尚不清楚， 尤其是对认知功能至关重要的大脑区域，如前额叶皮质(PFC)。 一个关键可能在于神经回路如何同步刺激附近的小胶质细胞运动--即主动伸展 以及精细细胞过程的撤回--特别是这种关系在整个过程中是如何变化的 青春期，是PFC和高级认知发展的关键时期。此外，性别差异也有 已经在小胶质细胞功能的某些方面得到了证实。阐明性别如何调节小胶质细胞在 PFC回路的发展是至关重要的，特别是考虑到青少年易感性方面的显著性别差异 精神疾病的发作，如精神分裂症。 本项目的目标是对脑内神经胶质细胞-神经元-回路相互作用有一个基本的了解。 哺乳动物的前额叶皮质。计划中的方法(目标1)使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质(MPFC)中阐明结构如何 小胶质细胞的动力学是由神经元活动和局部回路中的振荡同步性驱动的。这将是 在从青春期前到成年早期的不同时间窗口进行检查，并比较男性和 女性。(目标2，3)测试小胶质细胞活动是否、如何以及何时是建立成人所必需的 MPFC功能，在青春期和早期的限制窗口期间，小胶质细胞将被选择性地消除 使用药理学策略的成年期。然后在成年期，性和青春期对 I)(目标2)mPFC(函数网络聚类，Gamma)时空电路动力学的发展 振荡，β-伽马耦合)将使用双光子钙成像和密集电学来测量 录音和ii)(目标3)PFC依赖的认知将通过已建立的基于气味的注意来评估 移位任务。 该项目使用最先进的光学技术来研究具有细胞行为的动物的大脑功能- 水平精度。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 与疾病相关的神经免疫功能障碍，这个项目的基本科学见解，特别是由 按性别和发育期分层的方法可能改变对核心病理生理学的搜索 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.