Lateral Pontine Neurons in the Control of Breathing

描述（由申请人提供）：有大量证据表明，侧脑桥内的神经元在神经发生、控制和调节呼吸中起着重要作用。从出生的那一天起，神经活动的扰动就会显著地改变呼吸。本建议的基本目标是系统分析侧脑桥，这是一个重要但鲜为人知的呼吸控制区域。我们的初步数据表明，从臂旁复合体向腹侧延伸的中等密度的侧脑桥神经元走廊，单突触地投射到腹侧延髓内的呼吸神经元，即腹侧呼吸组（VRG），通常被认为是呼吸节律和模式产生的关键区域。具体是哪些VRG神经元接受了这种输入还不清楚，就像产生这种连接的脑桥神经元的性质一样。针对VRG的脑桥神经元的放电模式（强直性或相性呼吸）尚不清楚，它们的递质为VRG神经元提供突触输入的兴奋性或抑制性也不清楚。虽然VRG突出的脑桥区域的连续性质表明它们形成了一个与呼吸有关的宏观结构，但其不同节段的不同解剖连接表明多达5个离散的官能团。将使用多种技术来解决以下具体问题：1)负责控制吸气和呼气持续时间的侧脑桥神经元在哪里？它们是否表现出阶段性呼吸放电模式？2)解剖学上定义的VRG神经元的哪一类接受来自每个确定区域的脑桥神经元的单突触输入，它们使用哪些快速氨基酸递质？3)单个脑桥神经元与特定VRG神经元的活动模式和单突触连接是否与计算模型预测的它们在呼吸节律和模式控制中的选择性作用一致？化学刺激和抑制将识别离散的脑桥神经元簇，改变已识别的VRG神经元的活动和呼吸节律。顺行标记的脑桥轴突的光镜和电镜（EM）分析将与逆行标记和神经化学标记物（如神经激肽-1受体）的存在相结合，以区分本体球和球脊髓VRG神经元亚群以及颅运动神经元。交叉相关分析和峰值触发平均将用于评估侧脑桥呼吸细胞和电生理学定义的VRG神经元之间的功能关联。

DESCRIPTION (provided by applicant): Evidence is substantial that neurons within the lateral pons play a fundamental role in the neurogenesis, control and modulation of breathing. From the day of birth, perturbation of its neuronal activity significantly alters breathing. The fundamental goal of this proposal is the systematic analysis of the lateral pons, an important but poorly understood region involved in respiratory control. Our preliminary data indicate that a moderately dense corridor of lateral pontine neurons extending ventrally from the parabrachial complex, monosynaptically projects to respiratory neurons within the ventrolateral medulla, i.e., the ventral respiratory group (VRG), generally accepted as a crucial region in the generation of respiratory rhythm and pattern. The specific VRG neurons receiving this input are unclear, as is the nature of the pontine neurons giving rise to this connection. The discharge pattern (tonic or phasic respiratory) of pontine neurons targeting the VRG is not known, nor is the excitatory or inhibitory nature of their transmitters providing synaptic inputs to VRG neurons. Although the contiguous nature of the VRG projecting pontine regions suggests they form a respiratory related macrostructure, distinct anatomical connections for its different segments suggests as many as 5 discrete functional groups. A combination of techniques will be used to address the following Specific Aims. 1) Where are the lateral pontine neurons responsible for controlling inspiratory and expiratory durations and do they exhibit phasic respiratory discharge patterns? 2) Which anatomically defined classes of VRG neurons receive monosynaptic inputs from pontine neurons in each identified region, and what fast amino acid transmitters do they use? 3) Are activity patterns and monosynaptic connections of individual pontine neurons onto specific VRG neurons consistent with their selective role in respiratory rhythm and pattern control as predicted by computational models? Chemical stimulation and inhibition will identify discrete pontine neuron clusters that change the activity of identified VRG neurons and respiratory rhythm. Light and electron micrographic (EM) analysis of anterogradely labeled pontine axons will be combined with retrograde labeling and the presence of neurochemical markers (e.g., neurokinin-1 receptors) to distinguish propriobulbar and bulbospinal VRG neuron subgroups and cranial motoneurons. Cross-correlation analysis and spike-triggered averaging will be used to assess functional associations between respiratory cells of the lateral pons and electrophysiologically defined VRG neurons.