Physiology of Vestibular Compensation

描述（由申请人提供）：来自一个迷路的前庭信号的中断导致由高频、高加速度头部运动诱发的角前庭眼反射（VOR）的不对称。上一个资助期的研究阐明了松鼠猴角VOR的线性和非线性成分，证明了放大或缩小眼镜对这些成分的选择性适应，比较了松鼠猴和猕猴对快速旋转的水平角VOR，定义了前庭神经传入对头部快速旋转的反应特性，并分析了角VOR、传入、庆大霉素单侧耳毒性前庭损伤后的毛细胞。 拟议的研究建立在以前的成就，通过研究，分为三个具体目标。实验是在龙猫和猕猴中进行的。目标I中的研究将定义前庭神经传入对加速步骤的反应，并研究不规则放电传入对这些快速头部旋转诱发的水平VOR的贡献。输送到每个迷路的双侧阳极电流将用于在快速头部旋转期间显著减弱或沉默不规则传入。在猕猴中进行的实验将涉及正常VOR的分析以及随后的斗争诱导的适应。目的二将调查的贡献VOR补偿的保留静息率传入一侧的前庭病变和传入的contralesional（完整）的迷路。保留静息频率但消除或明显减弱运动反应的单侧病变涉及鼓室内注射庆大霉素。目的III将研究猕猴单侧延髓切除后水平VOR代偿性变化的神经相关性。这些实验将确定单侧前庭神经切除术后对侧前庭神经传入神经的放电特性是否发生变化。将在单侧前庭神经切除术后研究前庭核神经元介导VOR的动力学。本体感受输入和预期机制在修改这些中枢神经元的反应中的作用将通过比较主动和被动产生的头对身体和全身旋转期间的神经元反应来确定。

DESCRIPTION (provided by applicant): Disruption of vestibular signals from one labyrinth results in asymmetries in the angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration head movements. Studies during the previous funding period have elucidated linear and nonlinear components of the angular VOR in the squirrel monkey, demonstrated selective adaptation of these components with magnifying or minimizing spectacles, compared the horizontal angular VOR in squirrel monkeys and macaques in response to rapid rotations, defined the response properties of vestibular-nerve afferents to rapid head rotations, and analyzed changes in the angular VOR, afferents, and hair cells following unilateral ototoxic vestibular injury with gentamicin. The proposed research builds upon previous accomplishments through studies that are organized into three specific aims. The experiments are performed in chinchillas and in macaques. Studies in Aim I will define the responses of vestibular-nerve afferents to steps of acceleration and study the contributions of irregularly discharging afferents to the horizontal VOR evoked by these rapid head rotations. Bilateral, anodal galvanic currents delivered to each labyrinth will be used to substantially attenuate or silence irregular afferents during rapid head rotations. The experiments that are conducted in macaques will involve analysis of the normal VOR as well as following spectacle-induced adaptation. Aim II will investigate the contribution to VOR compensation of preserved resting rate in afferents on the side of a unilateral vestibular lesion and of afferents from the contralesional (intact) labyrinth. The unilateral lesion that preserves resting rate but abolishes or markedly attenuates responses to motion involves intratympanic injection of gentamicin. Aim III will examine neural correlates of compensatory changes in the horizontal VOR in macaques after unilateral labyrinthectomy. These experiments will determine if the discharge properties of vestibular-nerve afferents on the contralateral side change following unilateral labyrinthectomy. The dynamics of vestibular nuclei neurons that mediate the VOR will be studied following unilateral labyrinthectomy. The role of proprioceptive inputs and anticipatory mechanisms in modifying the responses of these central neurons will be determined by comparing neuronal responses during actively and passively generated head-on-body and whole-body rotations.