NEURAL MECHANISMS CONTROLLING BREATHING IN MAMMALS

该项目旨在提供以下信息 参与产生和控制的基本神经机制 哺乳动物的呼吸运动。长期目标是 解释呼吸运动的个体发生和神经发生 分子、生物物理、突触和网络术语 哺乳动物脑干和脑干呼吸神经元的特性 脊髓。目前的工作重点是蜂窝和网络 脑干呼吸节律的产生机制。一个 一系列相互关联的多学科研究正在进行中，以 确定：脑干的位置、细胞组件和架构 参与呼吸道病毒产生和传播的网络 神经元的节律、生物物理特性和突触相互作用 形成呼吸振荡器；神经化学机制 用于节奏的调制和突触传递。实验 用体外分离的脑干-脊髓和 取自胎儿、新生儿和青少年的脑干切片 啮齿动物。关键的脑干基因座包含了 产生节律的神经元已经被识别出来。新方法 被开发来分离这个基因座(称为前博辛格 复合体)在保留功能的髓质薄片中 主动呼吸网络，允许进行实验分析 蜂窝和网络级别的并发机制。我们有 进一步开发新的方法，用于实时结构和 节律产生神经元的功能成像 红外照明和差分干涉对比(IR-DIC) 神经元的光学成像与荧光成像同时进行 用钙敏感染料标记。这种成像方法具有 简化的节律产生神经元的识别 生物物理和突触特性的电生理学研究。 通过这些方法，我们已经对呼吸活动进行了成像 在体外培养的前Botzinger复合体中的起搏神经元，提供 到目前为止最直接的实验证据是 产生涉及到具有特殊起搏器特性的神经元。 这些结果继续支持我们的混合起搏器网络 从以前的工作中形成的解释节奏的模型 一代。计算方法已经被并行使用。 用来模拟呼吸神经元和网络的实验研究。 我们的起搏器的生物物理现实计算模型 神经元已经被提炼，并进行了新的研究 关于突触耦合种群的动态行为 这些细胞。使用这些模型的模拟模拟了许多功能 实验中发现的神经元活动和突触相互作用 在试管中。基于计算机的方法也得到了进一步的改进， 生成这些模拟的动画，允许可视化 模型神经元及其网络的动态行为 互动。这些模型目前正被应用于进一步 探索和可视化呼吸系统的操作原理 神经系统发育不同阶段的振荡器。

This project is designed to provide information on basic neural mechanisms involved in the generation and control of respiratory movements in mammals. The long-range goal is to explain the ontogeny and neurogenesis of respiratory movements in terms of the molecular, biophysical, synaptic, and network properties of respiratory neurons in the mammalian brainstem and spinal cord. Current work focuses on cellular and network mechanisms generating the respiratory rhythm in the brainstem. A set of interrelated, multidisciplinary studies are ongoing to determine: sites, cellular components, and architecture of brainstem networks involved in generation and transmission of respiratory rhythm; biophysical properties and synaptic interactions of neurons forming the respiratory oscillator; and neurochemical mechanisms for modulation and synaptic transmission of rhythm. Experiments are performed with isolated in vitro brainstem-spinal cord and brainstem slice preparations from fetal, neonatal, and juvenile rodents. The critical brainstem locus containing the populations of neurons generating the rhythm has been identified. Novel methods were developed to isolate this locus (called the pre-Botzinger complex) in thin slices of the medulla which retain functionally active respiratory networks, allowing experimental analysis of mechanisms concurrently at cellular and network levels. We have further developed novel methods for real-time structural and functional imaging of the rhythm generating neurons utilizing infrared illumination and differential interference contrast (IR-DIC) optics simultaneously with fluorescence imaging of the neurons labeled with calcium-sensitive dyes. This imaging approach has facilitated identification of the rhythm generating neurons for electrophysiological studies of biophysical and synaptic properties. With these approaches, we have imaged the activity of respiratory pacemaker neurons in the pre-Botzinger complex in vitro, providing the most direct experimental evidence to date that rhythm generation involves neurons with specialized pacemaker properties. These results continue to support our hybrid pacemaker-network model which was formulated from previous work to explain rhythm generation. Computational approaches have been used in parallel to experimental studies to model respiratory neurons and networks. Our biophysically realistic computational models of the pacemaker neurons have been refined and novel investigations were conducted on the dynamic behavior of synaptically-coupled populations of these cells. Simulations with these models mimic many features of the neuron activity and synaptic interactions found experimentally in vitro. Computer-based methods have also been further refined to produce animations of these simulations, allowing visualization of the dynamic behavior of the model neurons and their network interactions. These models are currently being applied to further explore and visualize principles of operation of the respiratory oscillator at different stages of nervous system development.