Unraveling respiratory rhythm generation in the medullary network

项目总结 呼吸对生存至关重要，呼吸失败是致命的。这在以下背景下变得悲剧性地显而易见： 目前的阿片类药物危机。呼吸障碍也是睡眠呼吸暂停的原因，睡眠呼吸暂停是另一种健康问题 流行病比例问题。所有这些干扰的核心是位于 脑干。其中两个网络是Prebötzinger复合体(PrebötC)和面旁呼吸群 (PFRG)被认为分别引起灵感和主动呼气。在最初的资助过程中 在这项资助期间，我们发现了第三个兴奋性微回路，吸气后复合体(Pico)，它给出 进入第三个呼吸阶段：吸气后--吸气后的呼气阶段。基于我们的 我们提出了三重振荡器假说：即三个激励性微电路(PrebötC，pFRG， 皮科)产生了呼吸的三个阶段。然而，皮科的发现引发了一个重要的、 悬而未决的问题：所谓的Bötzinger复合体(BötC)的作用是什么？ 呼吸神经元，位于PrebötC的顶部？ 在这里，我们测试了最重要的假设，即PrebötC并不像之前认为的那样是一个小的微电路，但 这个网络形成了一个与BötC相邻的动态调节的列。本专栏的范围是 受突触抑制、化学和机械感觉传入的动态调节。该项目对此进行了测试 三个特定目标的假说：Aim 1描绘了沿髓柱呼吸活动的程度。我们 将使用电生理、钙成像和光遗传学方法来表征神经元 这根柱子里的放电模式。目标2研究了控制这一程度的细胞决定因素 使用细胞内和光遗传学记录的柱子。我们专门测试了一个假设，即平衡 在突触抑制和兴奋之间，调节柱状突触的规律性、频率和空间范围。 为了进行目标1和目标2，我们将使用水平脑干切片来隔离整个腹侧延髓和 可以接受严格的蜂窝和网络分析。目标3探讨了动态调节 在警戒和麻醉的活体动物中。我们检验了迷走神经和化学感觉的假设 通过激活抑制神经元，传入神经元在调节该柱的空间范围方面起着关键作用 能够收缩和扩展吸气节律网络。拟议的研究可能会导致 为了更好地理解这个基本问题：大脑是如何产生有节奏的运动活动和 它如何整合感官信息。所获得的见解也将对理解 与呼吸相关的死亡率和发病率背后的细胞和系统水平机制 精神错乱。

PROJECT SUMMARY Breathing is vital for survival, and failure to breathe is fatal. This has become tragically evident in the context of the current opioid crisis. Breathing disturbances are also the cause of sleep apnea, which is another health issue of epidemic proportions. At the core of all these disturbances are neuronal networks located within the brainstem. Two of these networks, the preBötzinger complex (preBötC) and the parafacial respiratory group (pFRG) are thought to give rise to inspiration and active expiration, respectively. During the initial funding period of this grant, we identified a third excitatory microcircuit, the postinspiratory complex (PiCo), which gives rise to a third breathing phase: postinspiration – the expiratory phase that follows inspiration. Based on our discovery, we proposed the triple oscillator hypothesis: i.e. three excitatory microcircuits (preBötC, pFRG, PiCo) give rise to the three phases of breathing. However, the discovery of PiCo raised an important, unresolved issue: what is the role of the so-called Bötzinger complex (BötC), a fourth region that contains respiratory neurons, and that is located rostral of the preBötC? Here we test the overarching hypothesis that the preBötC is not a small microcircuit, as previously thought, but that this network forms a dynamically regulated column contiguous with the BötC. The extent of this column is dynamically regulated by synaptic inhibition, chemo- and mechanosensory afferents. The project tests this hypothesis in three specific aims: Aim 1 maps the extent of respiratory activity along the medullary column. We will use electrophysiological, calcium imaging and optogenetic approaches to characterize the neuronal discharge patterns within this column. Aim 2 investigates the cellular determinants that control the extent of this column using intracellular and optogenetic recordings. We specifically test the hypothesis that a balance between synaptic inhibition, and excitation regulates the regularity, frequency and spatial extent of the column. To conduct aims 1 and 2 we will employ horizontal brainstem slices that isolate the entire ventral medulla and that are amenable to a rigorous cellular and network analysis. Aim 3 explores the dynamic regulation of the column in alert and anesthetized in vivo animals. We test the hypothesis that vagal and chemosensory afferents play a critical role in regulating the spatial extent of this column by activating inhibitory neurons that are capable of shrinking and extending the inspiratory rhythmogenic network. The proposed research may lead to a better understanding of the fundamental question: how the brain generates rhythmic motor activity and how it integrates sensory information. Insights gained will also have important implications for understanding the cellular and systems level mechanisms underlying the mortality and morbidity associated with breathing disorders.