The role of Dbx1-derived medullary neurons for rhythm generation in the intact respiratory network

1：项目总结 呼吸是一种复杂的行为，对所有哺乳动物的生命来说都是基本的。功能和功能上的干扰 呼吸协调在许多中枢神经系统疾病中很常见。因此，研究 这种行为背后的特定神经群体不仅具有极大的基础科学兴趣，而且具有很高的研究价值。 临床意义。损伤实验和使用横断脑干切片的体外研究已经定义 对于吸气阶段来说是必要和充分的最小回路，是呼吸的一个小的“核心”。 延髓腹外侧区的神经元称为Prebötzinger复合体(PrebötC)。兴奋性神经元来源 来自表达转录因子Dbx1的细胞被认为形成了PrebötC的节律性“核心”。 然而，每次呼吸后刺激Dbx1的“不应期”限制了这些神经元的能力。 在体外驱动高频节律。这一特定的神经元群体在控制广度 体内常见的呼吸频率范围尚不清楚。在这个项目中，我们将使用新的体内和体外 采用平行方法研究Dbx1神经元在产生灵感过程中的作用 嵌入更广泛的髓质网络中。根据我们的初步数据，我们假设吸气 神经网络的作用就像一个分布式的柱，并不局限于一个定义的“核心”区域。抑制 兴奋性Dbx1神经元通过抑制后反弹有效地驱动吸气节律。还有， 在分布式吸气网络中可以缩短Dbx1的不应期，以允许更快的呼吸 短暂性突触抑制的调节机制的频率。这些假说将得到检验。 利用强大的光遗传学、电生理、药理学和成像技术在麻醉和 自由行为小鼠(Aim1)和一种新的水平脑干切片制剂，该制剂保留了更宽的 双侧延髓网(AIM2)。我们期望这些准备工作的整合将提供一个独特的 透视呼吸节律产生领域中仍未解决的问题。

1: PROJECT SUMMARY Breathing is a complex behavior that is fundamental for life in all mammals. Disturbances in the function and coordination of breathing are common in many disorders of the central nervous system. Thus, the study of specific neural populations that underlie this behavior is not only of great basic science interest, but holds high clinical significance. Lesion experiments and in-vitro studies using transverse brainstem slices have defined the minimal circuitry that is necessary and sufficient for the inspiratory phase of breathing, a small “kernel” of neurons in the ventrolateral medulla termed the preBötzinger Complex (preBötC). Excitatory neurons derived from cells expressing the transcription factor Dbx1 are thought to form the rhythmogenic “core” of the preBötC. However, a “refractory period” for Dbx1 stimulation following each breath limits the ability these neurons to drive a high frequency rhythm in-vitro. The role of this specific population of neurons in controlling the wide range of breathing frequencies common in-vivo is unknown. In this project we will use novel in-vivo and in-vitro approaches conducted in parallel to investigate the role of Dbx1 neurons in the generation of inspiration when embedded in the wider medullary network. Based on our preliminary data, we hypothesize that the inspiratory neural network functions as a distributed column, and is not limited to a defined “core” region. Inhibition of excitatory Dbx1 neurons effectively drives the inspiratory rhythm through post-inhibitory rebound. And, the refractory period for Dbx1 can be reduced in the distributed inspiratory network to allow faster breathing frequencies by modulating mechanisms of short-term synaptic depression. These hypotheses will be tested using powerful optogenetic, electrophysiological, pharmacological and imaging techniques in anesthetized and freely behaving mice (Aim1) and in a novel horizontal brainstem slice preparation that preserves the wider medullary network bilaterally (Aim2). We expect that integration of these preparations will provide a unique perspective to examine issues that remain unresolved in the field of respiratory rhythm generation.