PHYSIOLOGY OF VESTIBULAR COMPENSATION

负责正常控制前庭突起的中枢通路 接收关于在放电中编码的头部运动的信息 支配每个迷路的前庭神经传入的特性。 这些来自前庭末端器官一侧输入的改变会导致结果 在扭曲的前庭反射中，并唤起补偿机制。 单侧前庭病变后的变化及 调节代偿的神经生理事件知之甚少。 将对警觉松鼠进行行为和单个单位的研究 猴子确定角状前庭-眼的代偿机制 两个单侧前庭病变后的反射。一处病变 范式将涉及到三个方面的单方面机械失活 半规管和另一条将由单侧构成 迷路切除联合前庭神经切除。根管封堵保存了 前庭神经传入的紧张性放电而迷路切除术 前庭神经切除会导致永久性的消融 患侧前庭传入活动。 这两个前庭病变将用于解决三个具体目标。 I)每个前庭病变对增益和对称性的行为影响 角度水平和垂直前庭眼球反射(VORS) 将在警觉的松鼠猴子身上进行研究，这些猴子被训练成注视目标光 并做出流畅的追逐眼球动作。强直性前庭的作用 根管封堵后保留传入活动恢复VOR增益 对称性将被定义。2)中环的射击特点 分离在前庭核团中的前庭神经元将被记录在 警觉的，训练有素的松鼠猴子来确定神经生理学基础 每一次前庭病变后VORS的变化情况。3) 中枢性前庭神经元对电极化的反应 通过植入的迷宫刺激电极传递 学习。非损毁迷路前庭传入在大鼠脑损伤中的作用 两个前庭病变后的代偿机制将 从而被刻画出来。 这些研究将加深我们对正常前庭的理解 过程，并有助于定义塑性过程和 在这个系统中的适应性。本提案中描述的研究是 与前庭疾病的诊断和治疗直接相关 在人类身上。

Central pathways responsible for control of vestibular processes normally receive information about head movements encoded in the discharge properties of vestibular-nerve afferents innervating each labyrinth. Alteration of these inputs from vestibular end-organs on one side results in distorted vestibular reflexes and evokes mechanisms of compensation. The changes following unilateral vestibular lesions and the neurophysiological events mediating compensation are poorly understood. Behavioral and single-unit studies will be performed in alert squirrel monkeys to define mechanisms of compensation in angular vestibulo-ocular reflexes after each of two unilateral vestibular lesions. One lesion paradigm will involve unilateral mechanical inactivation of the three semicircular canals and the other will consist of unilateral labyrinthectomy with vestibular neurectomy. Canal plugging preserves the tonic discharge of vestibular-nerve afferents whereas labyrinthectomy with vestibular neurectomy results in a permanent ablation of all vestibular afferent activity on the lesioned side. These two vestibular lesions will be used to address three specific aims. I) The behavioral effects of each vestibular lesion on gain and symmetry of the angular horizontal and vertical vestibulo-ocular reflexes (VORs) will be studied in alert squirrel monkeys trained to fixate target lights and make smooth pursuit eye movements. The role of tonic vestibular afferent activity preserved after canal plugging in recovery of VOR gain and symmetry will be defined. 2) The firing characteristics of central vestibular neurons isolated in the vestibular nuclei will be recorded in alert, trained squirrel monkeys to determine the neurophysiological basis of changes observed in the VORs after each of the vestibular lesions. 3) The responses of central vestibular neurons to galvanic polarizations delivered through implanted labyrinthine stimulating electrodes will be studied. The role of vestibular inputs from the nonlesioned labyrinth in mechanisms of compensation after each of the two vestibular lesions will thereby be characterized. These studies will enhance our understanding of normal vestibular processes and contribute to defining processes of plasticity and adaptation in this system. Research described in this proposal is directly relevant to the diagnosis and treatment of vestibular disorders in humans.