AXON STRUCTURE /FUNCTION BEFORE AND AFTER EIGHTH NERVE CUT

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用于研究 个体水平半圆的脑干差异性分布 蟾鱼Opsanus tau的运河传入神经。这根神经管含有 大约350个初级传入神经。每个传入信号都带有一个信号 与头部运动有关。利用足够的刺激，这些信号 被分成三个粗略的组：a)低增益速度 灵敏，b)高增益速度敏感度，以及3)加速度敏感度 传入器。初步研究表明，每组传入神经元 终末在前庭核团的离散部分内终止 小脑以及重叠的常见部位。来自的输出 像所有脊椎动物一样，单个前庭核团被定向到 神经轴内的不同部位。那里有凸出的鸡冠 神经细胞，例如，眼外运动核团，ipsi-和 对侧投射脊髓神经元，向同侧投射 对侧脑干，以及向其他部位的投射。对于 目前的研究，个人传入，生理上由他们的识别 在充分刺激期间，独特的信号将被注入到 用HRP或生物细胞素轴向显示它们的轴突和侧支， 终端场和体细胞形态。传入神经元将是 将计算机重建和形态信息输入数字 用于后续分析的内存。我们将研究相关参数，如 作为胞体大小、轴突直径、轴突分支的数目和方式、位置 轴突终末数和终末末梢数。假设1至 被测试的是；在从第七神经传递信息时 到其中心目标的纤维的结构和末端轨迹 不同的生理信号与它们不同的功能相平行。 假设2是；功能不同的生理传入 信号将被转移到适当的次级神经元。这将是 通过评估旋转过程中的响应动力学进行测试 鉴定出次级神经元。椎体内电生理学 初级传入的电脉冲刺激也将被用来评估 大鼠单、多突触后电位的差异 不同的脑干靶点神经元。假设3是；下面是 神经部分，再生传入会找到合适的 脑干目标和重新连接，转移适当的 将生理信号传递给大脑中正确的次级神经元 前庭核团。再生传入神经的结构和功能 并对它们的目标神经元进行严格的以上评估 提到了形态和生理技术。

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.