COLLICULAR DEVELOPMENT

共同发展

• 批准号: 3258694
• 负责人: ROBERT W RHOADES
• 金额: $ 7.02万
• 依托单位: UNIVERSITY OF TOLEDO HEALTH SCI CAMPUS
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-07-01 至 1992-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3258694
• 关键词: afferent nerve; axon; brain subcortex; dendrites; efferent nerve; electrophysiology; evolution; experimental brain lesion; hamsters; histology; neuroanatomy; neurogenesis; neuropharmacology; newborn animals; nontherapeutic iontophoresis; retina; single cell analysis; somesthetic sensory cortex; superior colliculus; sympathetic nervous system; synapses; visual pathways

The goal of the research proposed is to understand, at the level of individual cells and fibers, the substrate of the functional reorganization that follows neonatal deafferentation of the hamster's superior colliculus (SC). The particular experiments outlined in this application are designed to examine three aspects of the collicular reorganization that occurs after neonatal enucleation of one eye. These are: 1. Reorganization of the axon arbors of individual, functionally characterized retinal and subcortical somatosensory afferents, 2. Effects of deafferentation upon structure-function relationships for postsynaptic cells, and 3. The role which sprouting of noradrenergic (NA) afferents plays in deafferentation induced functional reorganization. Extracellular recording studies have already shown that neonatal enucleation markedly alters the response properties of many SC neurons and "bulk tracing" experiments have demonstrated further that part of this reorganization might be explained by alterations in the terminal fields of several of the residual projections to the tectum. We will use intra-axonal recording and horseradish peroxidase (HRP) injection techniques to determine whether the expansion of the remaining retinal and subcortical somatosensory inputs to the SC reflects collateral sprouting; i.e., increases in the arbors of individual axons, "spreading" of azon terminals, i.e., an increase in the extent of the terminal arbors of a given axon will a concomitant decrease in their density or reduced overlap of normally sized arbors from different axons. We will also employ intracellular recording and HRP injection to define the receptive fields and structure of postsynaptic cells in the deafferented SC. A number of morphological studies have suggested that changes in the dendritic architecture of partially deafferented neurons may also play an important role in functional reorganization. Our experiments will test this hypothesis directly at the level of individual cells. In a third set of experiments, we will examine the role that sprouting of NA axons plays in the physiological changes observed in the deafferented SC. Our previous studies have demonstrated that NA fibers sprout vigorously after neonatal enucleation and our working hypothesis is that these afferents may act to inhibit the expression of weak sensory inputs onto SC neurons.

提出的研究的目的是了解 单个细胞和纤维，功能的底物 重组，遵循新生儿的剥夺 仓鼠的上丘（SC）。 特定的实验 本应用程序中概述的旨在检查三个方面 新生儿后发生的胶质重组 一只眼睛的诱因。 这些是：1。轴突的重组 个体的乔木，功能表征的视网膜和 皮层体体感传入，2。 对结构功能关系的脱颖而出 突触后细胞和3。发芽的作用 脱甲肾上腺素（Na）传入诱导的脱efterentation 功能重组。 细胞外记录研究 已经表明，新生儿摘除显着改变了 许多SC神经元和“散装跟踪”的响应特性 实验进一步证明了这部分 重组可以通过终端的变化来解释 几个残留投影的田地。 我们 将使用轴内记录和辣根过氧化物酶（HRP） 注射技术确定是否扩展 剩余的视网膜和皮层亚体感输入SC 反映附带发芽；即，增加 单个轴突，Azon终端的“扩散”，即增加 给定轴突的末端轴向的范围将 伴随的密度降低或降低 通常来自不同轴突的大小乔木。 我们还将雇用 细胞内记录和HRP注射以定义接受 断层SC中突触后细胞的场和结构。 许多形态学研究表明 部分脱附神经元的树突状建筑可能 在功能重组中也起着重要作用。 我们的 实验将直接在 单个细胞。 在第三组实验中，我们将检查 Na轴突在生理中发挥作用的作用 在删除的SC中观察到的变化。 我们以前的研究 已经证明了Na纤维在 新生儿摘除和我们的工作假设是 传入可能会抑制弱感觉输入的表达 进入SC神经元。