Dynamic switching in the brainstem: a spatiotemporal mechanism for the neural control of breathing

项目总结 呼吸是生存所必需的，不呼吸会导致死亡。同时，精确而灵活的 控制呼吸对于维持动态平衡(例如，运动过程中的血液氧合)和 高阶功能，如发声。不可抗拒能力和灵活能力的神经控制 呼吸是由脑干中神经元的活动产生的。本质上有节奏的前Bötzinger情结 (PrebötC)被认为是驱动节律产生的核心或“核心”，而不是一个分布式的神经网络 从PrebötC向吻侧和向尾侧延伸的中心，称为腹侧呼吸柱(VRC)， 涉及呼吸的各个方面的控制(例如，吸气、呼气、叹息、喘息)。 损伤实验和从体外脑片分离的录音已经让我们深入了解了 控制呼吸作用的不同亚核。然而，目前尚不清楚这些神经元的活动是如何 在正常呼吸和喘息期间，种群动态协调以调整呼吸行为。 在这里，我们同时记录了大量在空间上分布的经遗传鉴定的单个 在体外和体内，VRC上的神经元。基于我们的初步数据，我们提出了一种新的“动态 转换“假设：协调神经网络招募离散但解剖学上重叠的 神经元驱动独特的呼吸行为。此外，呼吸作用(例如吸气/呼气) 单个神经元并不像目前认为的那样是静态的，而是动态的，并随着呼吸行为的变化而变化。这 假说类似于在运动步态中观察到的现象，其中离散的时空肌肉 模式会产生不同的运动模式(如行走、小跑、奔跑)。这项提案考验着 动态转换假说通过三个具体目标：目标1量化动态的和协调的 单个神经元在体外脑片和体内麻醉呼吸小鼠中的呼吸作用。我们雇佣了 最先进的高密度电生理学(神经像素)和光遗传学技术来识别 数百个同时记录的神经元的功能作用和遗传同一性，并比较 这些群体在体外和体内制剂之间的协调活动。目标2描述了如何 这些动态网络在喘息时重新配置。最后，在目标3中，我们证实了自由行为的结果 呼吸行为高度灵活的动物(例如，嗅探)，并由自上而下的中枢调节。

PROJECT SUMMARY Breathing is necessary for survival, and failure to breath results in death. Simultaneously, the precise and flexible control of breathing is crucial for maintaining homeostasis (e.g., blood oxygenation during exertion), and to serve higher order functions such as vocalization. The neural control for both the inexorable and the flexible capabilities of breathing arises from the activity of neurons in the brainstem. The intrinsically rhythmic pre-Bötzinger complex (preBötC) is thought to be the core or “kernel” driving rhythm generation, but a distributed network of neural centers that extend rostrally and caudally from the preBötC, known as the Ventral Respiratory Column (VRC), has been implicated in control of varied aspects of respiration (e.g., inspiration, expiration, sighing, gasping). Lesion experiments and isolated recordings from in-vitro brain slices have given insights into the roles of the different sub-nuclei that govern respiration. However, it remains unknown how the activity of these neuronal populations is dynamically coordinated to adjust respiratory behaviors during normal breathing and gasping. Here, we record simultaneously from large, spatially distributed populations of genetically identified single neurons across the VRC in-vitro and in-vivo. Based on our preliminary data, we propose a novel “dynamic switching” hypothesis: coordinated neural networks recruit discrete, but anatomically overlapping, populations of neurons to drive unique respiratory behaviors. Moreover, the respiratory role (e.g. inspiratory/expiratory) of individual neurons is not static, as is currently thought, but dynamic and changes with respiratory behavior. This hypothesis is analogous to phenomena observed in locomotor gaits in which discrete spatiotemporal muscle patterns give rise to discrete modes of movement (e.g. walking, trotting, galloping). This proposal tests the dynamic switching hypothesis through three specific aims: Aim 1 quantifies the dynamic and coordinated respiratory roles of single neurons in in-vitro brain slices and in-vivo in anesthetized, breathing mice. We employ state-of-the-art high-density electrophysiology (Neuropixels) with optogenetic techniques to identify the functional role and genetic identity of hundreds of simultaneously recorded neurons and compare the coordinated activity of these populations both between in-vitro and in-vivo preparations. Aim 2 describes how these dynamic networks reconfigure during gasping. Lastly, in Aim 3 we corroborate results in freely behaving animals where respiratory behaviors are highly flexible (e.g. sniffing) and are modulated by top-down centers.