AXON STRUCTURE /FUNCTION BEFORE AND AFTER EIGHTH NERVE CUT

第八次神经切断前后的轴突结构/功能

• 批准号: 3760638
• 负责人: STEPHEN M HIGHSTEIN
• 金额: --
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3760638
• 关键词: Osteichthyes; acoustic nerve; afferent nerve; alternatives to animals in research; axon; brain mapping; brain stem; digital imaging; electrophysiology; electrostimulus; horseradish peroxidase; intercellular connection; nervous system regeneration; neural information processing

Computer-aided reconstruction of normal, and regenerated individual vestibular primary afferent neurons will be employed in a study of the differential brainstem distribution of individual horizontal semicircular canal afferents in the toadfish, Opsanus tau. This canal nerve contains approximately 350 primary afferents. Each afferent carries a signal related to head movement. Utilizing adequate stimulation, these signals have been divided into three rough groups of: a) low gain velocity sensitive, b) high gain velocity sensitive, and 3) acceleration sensitive afferents. Preliminary studies indicate that each group of afferents terminate within discrete portions of the vestibular nuclei and cerebellum as well as in overlapping, common sites. The output from individual vestibular nuclei, as in all vertebrates, is directed to disparate sites within the neuraxis. There are rostrally projecting neurons innervating, e.g., the extra ocular motor nuclei, ipsi- and contralaterally projecting spinal neurons, projections to the ipsilateral and contralateral brainstem, and projections to other sites. for the present study, individual afferents, physiologically identified by their unique signals during adequate stimulation will be injected intra- axonally with HRP or biocytin to visualize their axons and collaterals, terminal fields, and somatic morphology. Afferent neurons will be computer-reconstructed and morphological information entered into digital memory for subsequent analysis. We will study relevant parameters such as soma size, axon diameter, number and mode of axonal branches, sites of axonal termination, and number of terminal boutons. Hypothesis 1 to be tested is that; in the transfer of information from the VIIIth nerve to its central targets the structure and terminal loci of fibers with diverse physiological signals parallels their diverse functions. Hypothesis 2 is that; functionally different physiological afferent signals will be transferred to appropriate secondary neurons. This will be tested by evaluating the response dynamics during rotation of identified secondary neurons. Intrasomatic electrophysiology following electric pulse stimuli of primary afferents will also be used to evaluate differences in mono- and poly- synaptic post synaptic potentials in different brainstem target neurons. Hypothesis 3 is that; following nerve section, regenerating afferents will find their appropriate brainstem targets and reconnect, transferring the appropriate physiological signals to the correct secondary neurons within the vestibular nuclei. The structure and function of regenerated afferents and their target neurons will be rigorously evaluated with the above mentioned morphological and physiological techniques.

正常和再生个体的计算机辅助重建 前庭初级传入神经元将被用于研究 个体水平半规管脑干差异分布 管传入的蟾鱼，Opsanus tau。 这条神经管包含 大约有350个初级传入神经 每个传入神经都携带一个信号 与头部运动有关。 利用适当的刺激，这些信号 已经被分为三个粗略的组：a）低增益速度 灵敏，B）高增益速度灵敏，以及3）加速度灵敏 传入神经 初步研究表明，每一组传入神经 终止于前庭核的离散部分内， 小脑以及重叠，共同的网站。 的输出 与所有脊椎动物一样，个体前庭核直接 神经轴内的不同部位。 有喙状突起 神经元支配，例如，眼外运动核团，同侧， 对侧投射脊髓神经元，向同侧的投射 和对侧脑干以及其他部位的投射。 为 目前的研究，个别传入，生理上确定的，他们的 在适当刺激期间的独特信号将被注射到 用HRP或biocytin观察轴突和侧支， 终端领域，和躯体形态。 传入神经元将 计算机重建和形态信息输入数字 用于后续分析。 我们将研究相关参数， 如索马大小、轴突直径、轴突分支的数目和方式、部位 轴突终止和终末终扣的数量。 假设1至 在第八神经的信息传递中， 其中心目标是纤维的结构和末端位点， 不同的生理信号对应着它们不同的功能。 假设2：功能不同的生理传入 信号将被传递到适当的次级神经元。 这将 通过评估旋转过程中的响应动力学进行测试， 识别次级神经元。 体内电生理学 初级传入神经的电脉冲刺激也将用于评估 单突触和多突触突触后电位的差异， 不同的脑干靶神经元。 假设3： 神经节，再生传入神经将找到合适的 脑干目标和重新连接，转移适当的 生理信号传递到正确的次级神经元， 前庭神经核 再生传入纤维的结构和功能 并且它们的靶神经元将被严格地评估， 提到了形态学和生理学技术。