Central Neuronal Activity in Vestibular Compensation

描述（由申请人提供）：本项目的目的是阐明灵长类动物前庭损伤（前庭补偿）恢复的机制。实验着重于单侧半规管切除术或半规管堵塞后前庭眼反射恢复的生理过程。这项研究将考虑在被动和主动头部运动过程中前庭反应的补偿。对于被动的头部运动，已经发现前庭补偿是不完全的。将使用外周前庭损伤前后的双侧前庭核喙侧的细胞外单单位记录来研究对平移和旋转运动的反射补偿的神经元底物。关于动态前庭反射补偿的中枢机制的假设将被直接检验。这些假设包括前庭连合系统可塑性的作用，以及耳石-眼系统的永久性缺陷是编码平移和重力信息的中枢神经元的线性加速度敏感性永久重新定向的结果。对于主动头部运动，初步研究通过分析脑损伤后无限制的眼睛和头部扫视运动（无头部凝视转移），研究了意志在头部运动期间代偿性眼反应中所起的作用。这些研究表明，受试者能够利用对头部运动和/或颈部或视觉反馈进行编码的神经信号的副本，以促进在自然、不受限制的头部运动期间的行为补偿。这项研究还将测试的假设，即在这些头部运动的神经信号编码的意志头部运动的副本，以修改这些中央前庭神经元的反应，促进在补偿动物的旋转运动的凝视稳定。这项研究是P.I.对前庭补偿的兴趣来自他以前的研究经验和他作为耳鼻喉科医生治疗头晕病人的工作。

DESCRIPTION (provided by applicant): The purpose of this project is to elucidate the mechanisms involved in recovery from vestibular injury (vestibular compensation) in primates. Experiments focus on the physiological processes underlying recovery of the vestibulo-ocular reflex following unilateral labyrinthectomy or plugging of the semicircular canals. The study will consider compensation of vestibular response during both passive and active head movements. For passive head movements, vestibular compensation has been found to be incomplete. The neuronal substrate for compensation of reflexes to both translational and rotational movement will be investigated using extracellular single unit recordings from the rostral bilateral vestibular nuclei both before and after peripheral vestibular lesion. Hypotheses concerning the central mechanisms of compensation of dynamic vestibular reflexes will be directly tested. These hypotheses include a role for plasticity in the vestibular commissural system and that permanent deficits in the otolith-ocular system are a result of permanent reorientation of the linear acceleration sensitivities of central neurons that encode translational and gravity information. For active head movements, preliminary studies have investigated the role played by volition in compensatory ocular responses during head movement by analyzing unrestrained eye and head saccadic movements (head-free gaze shifts) after labyrinthine lesion. These studies suggested that a subject is able to utilize copies of neural signals that encode head movements and/or cervical or visual feedback to facilitate behavioral compensation during natural, unrestrained head movements. This study will also test the hypothesis that copies of neural signals encoding volitional head movements are used during those head movements to modify the response of these central vestibular neurons, facilitating the stabilization of gaze during rotational movements in compensated animals. This research is an outgrowth of the P.l.'s interest in vestibular compensation developed from his previous research experience and from his work as an otolaryngologist treating patients complaining of dizziness.