DEVELOPMENT AND REGULATION OF AXON TERMINAL ARBORS

AXON 端子轴的开发和调节

• 批准号: 3397440
• 负责人: THOMAS N PARKS
• 金额: $ 14.68万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1981
• 资助国家: 美国
• 起止时间: 1981-07-01 至 1988-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3397440
• 关键词: afferent nerve; auditory deprivation; auditory stimulus; axon; brain stem; congenital deafness; electron microscopy; electrophysiology; histochemistry /cytochemistry; histology; neuroanatomy; neuropharmacology; nontherapeutic iontophoresis; sensory mechanism; synapses

The proposed work will investigate several basic aspects of neuron-target cell relations in the central nervous system (CNS). Of special interest are developmental interactions between afferent axons and target cells that determine the mature properties of specific synaptic connections in the auditory system. The seven proposed experiments will make use of the well-characterized avian brain stem auditory system, in particular the neurons of nucleus magnocellularis (NM). The methods to be employed in this work include surgery on young chick embryos, in vitro and in invo preparations of the brain stem, intracellular and extracellular electrophysiology, iontophoretic injection and histochemical staining of horseradish peroxidase, light- and electron-microscopic methods (including morphometry), and pharmacological analysis of synaptic transmission. It has recently been found that an anomalous functional projection from one NM to the contralateral NM can be experimentally induced by early surgical removal of the otocyst. This projection is a major one, providing functional input capable of synaptically driving NM cells on the side of otocyst removal. Further, it appears to form quite early in development. This anamalous projection offers the very unusual opportunity to examine the developmental consequences of "replacing" one type of afferent with a novel afferent input to the same group of target cells. Several aspects of the development of this novel auditory projection will be examined and contrasted with the development of normal cochlear nerve innervation of NM. In particular, questions about the relative influence of afferent axons or target neurons in specifying a particular property (e.g., axonal convergence ratio or neurotransmitter type) or in initiating a given developmental process (e.g., reduction in axonal branching) will be addressed. In addition, the proposed studies may provide an animal model for the central neural effects of congenital sensorineural hearing loss in humans and also permit critical tests of some current hypotheses about lesion-induced reactive synaptogenesis in the CNS.

拟议的工作将研究神经元目标的几个基本方面 中枢神经系统（CNS）中的细胞关系。 特别感兴趣 是传入轴突和靶细胞之间的发育相互作用 确定特定突触连接的成熟特性 听觉系统。 拟议的七个实验将利用 特征明确的鸟类脑干听觉系统，特别是 大细胞核（NM）的神经元。 所采用的方法 这项工作包括对雏鸡胚胎进行体外和体内手术 脑干细胞内和细胞外制剂 电生理学、离子电渗注射和组织化学染色 辣根过氧化物酶、光显微镜和电子显微镜方法（包括 形态测量）和突触传递的药理学分析。 最近发现，一个异常的功能投影 对侧 NM 的 NM 可以通过早期手术通过实验诱导 切除耳囊。 这个预测是一个重要的预测，它提供了 能够突触驱动侧 NM 细胞的功能输入 耳囊切除术。 此外，它似乎在发育的早期就形成了。 这种异常的投影提供了非常不寻常的机会来检查 用一种传入神经“替代”一种传入神经的发展后果 对同一组靶细胞的新传入输入。 几个方面 这种新颖的听觉投射的发展将被检查和 与正常耳蜗神经支配的发育形成对比 新墨西哥。 特别是关于传入神经的相对影响的问题 轴突或目标神经元指定特定属性（例如，轴突 收敛比率或神经递质类型）或启动给定的 发育过程（例如轴突分支的减少）将 已解决。 此外，拟议的研究可能提供动物模型 先天性感音神经性听力损失对中枢神经的影响 人类，还允许对一些当前的假设进行批判性测试 中枢神经系统损伤诱导的反应性突触发生。