Unraveling respiratory rhythm generation in the medullary network

描述（由申请人提供）：呼吸由沿着延髓腹外侧头端-尾侧轴分布的神经元网络（“腹侧呼吸柱”，VRC）产生。该网络产生三个不同的阶段：吸气（I）、吸气后（Post-I）和主动呼气（AE）。许多疾病都与不同形式的呼吸和对缺氧的反应有关。因此，了解这些呼吸阶段如何在各种条件下产生和动态调节，如缺氧，具有重要的基础科学和临床意义。在这个项目中，我们介绍了两种新的节奏活跃的脑干切片准备，使我们能够研究更广泛的延髓网络的突触，内在和调制特性的整合，在某种程度上是不可能的。基于我们的初步数据，我们提出了一个假设，即后I和灵感是由一个兴奋性柱产生的，该兴奋性柱从前Bötzinger复合体延伸到Bötzinger复合体。这种分布式兴奋性网络与GABA能和甘氨酸能机制以及内在膜特性相互作用，这些将在水平切片制备中使用各种电生理学、药理学和光遗传学方法进行探索（目的1）。在这个水平切片制备获得的见解将与从两个横向切片制备，隔离该兴奋柱的尾侧和喙侧部分（目标2）获得的数据进行比较。这种方法将使我们能够区分发生在尾侧和喙端的这列的节律发生机制。这些体外研究结果中揭示的概念将在自主呼吸体内制剂中进行测试（目的3）。我们期望这些新的体外制剂的引入，结合现代光遗传学技术和与体内方法的严格整合，将使我们能够重新审视现有的呼吸节律生成模型。这可能导致更好地理解在呼吸的神经控制领域的当前知识状态下仍然未解决和未解释的各种问题。

DESCRIPTION (provided by applicant): Breathing is generated by a neuronal network that is distributed along the rostro-caudal axis of the ventrolateral medulla ("ventral respiratory column", VRC). This network gives rise to three distinct phases: inspiration (I), post-inspiration (Post-I), and active expiration (AE). Many disorders are associated with disturbances in different forms of breathing and the response to hypoxia. Thus understanding how these phases of breathing are generated and dynamically regulated under various conditions such as hypoxia is of great basic scientific and clinical interest. In this project we introduce two novel rhythmicall active brainstem slice preparations that allow us to study the integration of synaptic, intrinsic and modulatory properties in the wider medullary network to an extent that was not possible before. Based on our preliminary data we propose the hypothesis that post-I and inspiration are generated by an excitatory column that extends rostrally from the pre-Bötzinger complex into the Bötzinger complex. This distributed excitatory network interacts with GABAergic and glycinergic mechanisms as well as intrinsic membrane properties that will be explored in the horizontal slice preparation using a variety of electrophysiological, pharmacological, and optogenetic approaches (Aim 1). Insights gained in this horizontal slice preparation will be compared with data obtained from two transverse slice preparations that isolate the caudal and rostral portion of this excitatory column (Aim 2). This approach will allow us to differentiate rhythmogenic mechanisms occurring at the caudal and rostral end of this column. Concepts revealed in these in vitro findings will then be tested in a spontaneously breathing in vivo preparation (Aim 3). We expect that the introduction of these novel in vitro preparations, combined with modern optogenetic techniques and a rigorous integration with in vivo approaches will allow us to revisit existing models of respiratory rhythm generation. This may lead to a better understanding of various issues that remain unresolved and unexplained at the current state of knowledge in the field of neural control of breathing.