PreBotzinger Circuit in Respiratory Rhythm Generation

描述（由申请人提供）：越来越多的证据表明，节律产生电路的一个重要组成部分位于延髓腹外侧的一个离散区域内，称为前Botzinger复合体。然而，要理解前Botzinger对呼吸的贡献，还需要对组成神经元的相关特性和网络相互作用进行全面描述。本项目的目标是提供一个合理的完整描述的呼吸神经元类型存在于preBotzinger复杂，包括其放电模式，响应激活选定的传入输入，神经递质（GABA，谷氨酸，甘氨酸）的内容和模式的突触连接形成与其他preBotzinger神经元。鉴于前Botzinger复合体的尺寸很小（在成年大鼠中，它长约0.6 mm，直径约1.5 mm，包括树突），我们可以提供这种分析。将有三个具体目标。在目的1中，细胞内或细胞外记录将用于根据放电模式及其对迷走神经和上级喉神经传入刺激的反应对神经元进行分类。然后将染料注入记录的神经元。随后在光和超微结构水平的免疫组织化学分析将确定神经递质含量（GABA，甘氨酸，谷氨酸）和它们的轴突投射模式。在目标2中，前B6tzinger神经元之间的突触相互作用将被确定与互补的电生理和解剖方法。在电生理学方法中，将使用尖峰触发平均或互相关方法与成对的神经元记录。在解剖学实验中，细胞内或细胞外标记将用于染色标记2个不同功能组的细胞，用于随后的突触相互作用的光和超微结构分析。在目标3中，我们将开发一个详细的计算模型的preB6tzinger呼吸网络使用所确定的神经元的属性和连接。要解决的假设是，神经元类型和突触内的preB6tzinger复杂的相互作用是足够的呼吸节律在体内产生。

DESCRIPTION (provided by applicant): There is increasing evidence that an essential component of the rhythm generating circuitry is located within a discrete region of the ventrolateral medulla termed the preBotzinger complex. Nevertheless, an understanding of the preBotzinger contribution to breathing awaits a comprehensive description of the pertinent properties and network interactions of the constituent neurons. The goal of this project to provide a reasonably complete description of the respiratory neuron types present in the preBotzinger complex, including their discharge patterns, response to activation of selected afferent inputs, neurotransmitter (GABA, glutamate, glycine) content and pattern of synaptic connections formed with other preBotzinger neurons. Given the small size of the preBotzinger complex (in the adult rat it is approximately 0.6 mm long and about 1.5 mm in diameter, including dendrites), it is within our means to provide this analysis. Three Specific Aims will be undertaken. In Aim l, intracellular or extracellular recording will be used to classify neurons with respect to discharge pattern and their response to stimulation of vagus and superior laryngeal nerve afferents. The recorded neurons will then be injected with dye. Subsequent immunohistochemical analysis at the light and ultrastructural levels will identify the neurotransmitter content (GABA, glycine, glutamate) and their axonal projection patterns. In Aim 2, synaptic interactions between preB6tzinger neurons will be identified with complementary electrophysiological and anatomical approaches. In the electrophysiological approach, either spike triggered averaging or cross-correlation approaches will be used with paired neuronal recordings. In anatomical experiments intra- or juxtacellular labeling will be used to dye-label cells in 2 different functional groups for subsequent light and ultrastructural analysis of their synaptic interactions. In Aim 3, we will develop a detailed computational model of the preB6tzinger respiratory network using the identified neuronal properties and connectivity. The hypothesis to be addressed is that the neuronal types and synaptic interactions within the preB6tzinger complex are sufficient for respiratory rhythm generation in vivo.