PHYSIOLOGY & ADAPTIVE CONTROL OF OTOLITH/OCULAR REFLEXES

前庭-眼反射(VOR)负责维持 头部运动时视网膜上图像的稳定性。许多人 行为特征和潜在的神经生理机制 角VORS的控制已被阐明。相对较少的是 已知耳石的组织--眼反射或其 适应能力。耳石-眼反射产生三种类型的 代偿性眼球运动：1)眼球反转 动态和静态磁头倾斜，2)动态响应的线性VORS 直线运动，以及3)恒速关闭引起的眼球震颤 垂直轴旋转。前庭神经传入神经支配 耳石不能区分导致这些运动的每一个 有三种回应。该项目中描述的研究将定义 信号处理中涉及的机制导致了这三个 回应。适应工作所涉及的能力和机制 耳石-眼反射也将作为一个例子来研究 运动学习。这项研究的长期目标是-定义 涉及规范和自适应控制的机制 耳石-眼反射，其实际目的是改善 前庭功能障碍的诊断与治疗(康复) 精神错乱。本提案的具体目标为：L)明确 前庭中枢神经元的生理特性 半规管和耳石传入在松鼠猴和 2)确定了角度自适应控制的机制 在松鼠猴子和人类身上都有线性VORS。三维 猴子和人类的眼球运动，以及 松鼠猴前庭核团的单位活动， 都会被记录下来。耳石-眼睛反射将被激发出来 到静态和动态头部倾斜、偏心旋转和线性 翻译。角速度信号的作用，相位主音 不规则耳石传入反应和频率特异性 在这些过程中对耳石信号的过滤将在中确定 猕猴双侧半规管闭塞及功能性 不规则传入神经的消融。将通过以下方式进行适应 视觉-前庭冲突范式。将适应的VOR增益转移到 半规管和半规管的不同组合引起的反射 耳石活动将识别这些路径中的汇合点 并定义了角速度产生过程中涉及的机制 来自耳石活动的信号。

Vestibulo-ocular reflexes (VORs) are responsible for maintaining stability of images on the retina during head movements. Many of the behavioral features and neurophysiological mechanisms underlying control of angular VORs have been elucidated. Comparatively little is known about the organization of otolith-ocular reflexes Or their adaptive capabilities. Otolith-ocular reflexes generate three types of compensatory eye movements: 1) ocular counterrolling in response to dynamic and static head tilt, 2) linear VORs in response to dynamic linear movements, and 3) nystagmus induced by constant velocity off vertical axis rotation. Vestibular nerve afferents innervating the otoliths cannot distinguish between movements leading to each of these three responses. Research described in this project will define mechanisms involved in the signal processing leading to these three responses. The capabilities and mechanisms involved in the adaptation of the otolith-ocular reflexes will also be studied as an example of motor learning. The long-term goal of this research is-to define the mechanisms involved in the specification and adaptive control of otolith-ocular reflexes, with the practical aim of improving the diagnosis and treatment (rehabilitation) of patients with vestibular disorders. The specific objectives of this proposal are l) to define the physiological properties of central vestibular neurons that receive both semicircular canal and otolith afferents in squirrel monkeys and 2) to define the mechanisms responsible for adaptive control of angular and linear VORs in both squirrel monkeys and humans. Three dimensional and vergence eye movements in both monkeys and humans, as well as single-unit activity in the vestibular nuclei of the squirrel monkeys, will be recorded. Otolith-ocular reflexes will be elicited in response to static and dynamic head tilt, eccentric rotations, and linear translations. The role of angular velocity signals, phasic-tonic responses of irregular otolith afferents, and frequency-specific filtering of otolith signals in these processes will be determined in monkeys through bilateral semicircular canal plugging and functional ablation of the irregular afferents. Adaptation will be elicited using visual-vestibular conflict paradigms. Transfer of adapted VOR gain to reflexes induced by differing combinations of semicircular canal and otolith activity will identify points of convergence in these pathways and define mechanisms involved in the generation of angular velocity signals from otolith activity.