BRAINSTEM PROJECTIONS TO CEREBRUM AND CEREBELLUM

这里提出的实验将确定和比较组织 来自中脑中缝核的发散轴突投射， 蓝斑和三叉神经核。 最近开发，敏感 将采用双逆行轴突追踪技术， 示踪剂小麦胚芽凝集素（WGA），N-[乙酰基-3H]和WGA缀合至 辣根过氧化物酶（HRP）以及荧光示踪剂在配对 这些脑干神经元投射靶点内的注射策略 组，以揭示其侧支和无分支轴突的顺序 预测。 组织的光和荧光显微镜分析 这些研究的部分将确定差异或相似之处， 存在于由以下原因引起的发散轴突投射的组织中 脑干单胺能神经元与感觉中继神经元 中脑和三叉神经髓核的神经元。 初步 实验表明，接受中脑中缝的每个CNS结构 投影在地形中有自己独特的表示法 中缝的不同部分。 中缝核神经支配的 具有彼此互连的结构通过以下方式相互关联： 一组在地形上明显不同的平行中缝投射 神经元 使用小的相关顺行轴突追踪实验 在中缝、蓝斑的部分内注射凝集素， 三叉神经核会显示出不同的地形图 这些目标结构内的组织和几何有序性 发散性投射的脑干神经元。 蓝斑，中缝， 三叉神经元都投射到前脑（例如，丘脑和 大脑皮层），中脑（例如，顶盖和中脑网状 形成），后脑（例如，小脑）和脊髓部位。 研究 这里提出的，试图解决不同的计划，组织 脑干神经元及其向各种中枢神经系统的轴突投射 系统结构将揭示脑干神经元 在大脑等结构中相互关联的神经元回路， 小脑皮质 当这些电路被改变时，通常 神经元损失的后果，中枢神经系统疾病状态，如 帕金森氏症或脑性麻痹可能会随之而来。 了解 脑干靶点的开发、维护及相关方案 电路将揭示原因和可能的治疗方法， 疾病

The experiments proposed here will determine and compare the organization of divergent axonal projections which arise from the midbrain raphe nuclei, locus coeruleus, and trigeminal nuclei. Recently developed, sensitive double retrograde axonal tracing techniques will be employed using the tracers wheat germ agglutinin (WGA), N-[acetyl-3H] and WGA conjugated to horseradish peroxidase (HRP) as well as fluorescent tracers in paired injection strategies within projection targets of these brainstem neuronal groups to reveal the order of their collateralized and unbranched axonal projections. Light and fluorescence microscopic analysis of tissue sections from these studies will determine differences or similarities that exist in the organization of divergent axonal projections arising from brainstem monoaminergic neurons versus those which arise from sensory relay neurons of the midbrain and medullary trigeminal nuclei. Preliminary experiments have revealed that each CNS structure receiving midbrain raphe projections has its own unique representation within a topographically distinct portion of the raphe. It also appears that raphe-innervated structures possessing interconnections with each other are interrelated by a topographically distinct group of collaterilized raphe projection neurons. Correlative anterograde axonal tracing experiments using small injections of lectins within portions of the raphe, locus coeruleus, and trigeminal nuclei will reveal different patterns of topographical organization and geometric orderliness within target structures of these divergently projecting brainstem neurons. Locus coeruleus, raphe, and trigeminal neurons all project to the forebrain (e.g., thalamus and cerebral cortex), midbrain (e.g., tectum and mesencephalic reticular formation), hindbrain (e.g., cerebellum) and spinal sites. Studies proposed here which attempt to resolve the different plans for organizing brainstem neurons and their axonal projections to various central nervous system structures will reveal the ways in which brainstem neurons interrelate neuronal circuitries in such structures as the cerebral and cerebellar cortices. When these circuits are altered, usually a consequence of neuronal loss, central nervous system disease states such as Parkinson's Disease or Cerebral Palsy can follow. Understanding the development, maintenance, and interrelative schemes of brainstem-target circuitries will shed light on the cause and possible treatments for such diseases.