VESTIBULAR INFLUENCES ON ARM MOVEMENTS

描述（由申请人提供）：我们想追求一种新的研究路线，关于前庭对手臂伸展运动的影响。所提出的实验的动机是最近在人类受试者中的发现，显示路径曲率更大，加速度持续时间更短，并且向上与向下手臂运动的峰值加速度增加。肌肉EMG活动和计算建模表明，这些运动学不对称性的产生是因为大脑使用重力作为向下运动期间加速和向上运动期间减速的主要力量。在这里，我们提出了一套基本的实验来检查前庭（耳石）信号是否在功能上对这些属性很重要。因此，本申请的目的是双重的。首先，以确定猕猴是否表现出类似的运动学和肌电图的不对称性，在垂直手臂运动中观察到的人类。第二，检查是否观察到的上/下不对称的手臂运动运动学和肌电图依赖于功能性前庭迷路。我们假设（1）猕猴，像人类一样，在执行上下（与水平）手臂运动时显示出运动学和EMG不对称性，（2）完整的前庭迷路对于检测重力和允许具有成本效益的垂直手臂运动规划具有重要的功能。为了实现这些目标，我们将测量手臂运动学（Optotrak），以及当猴子在正常动物和双侧坐骨神经切除术后执行中心向外和中心向内手臂运动时，激动剂和拮抗剂的EMG活动。为了进一步检查是否有任何长期的适应，我们将测试运动学和肌电图每周为头两个月后切除。这些实验将是第一个直接调查猕猴的重力相关耳石信号的规划和执行手臂运动的潜在作用。如果成功，我们将建立一个坚实的行为背景前庭影响手臂运动。未来的神经生理学研究可以探索与重力相关的前庭信号如何用于手臂运动规划和执行。

DESCRIPTION (provided by applicant): We want to pursue a novel line of research regarding vestibular influences upon arm reaching movements. The proposed experiments have been motivated by recent findings in human subjects showing that path curvature is greater, acceleration duration is shorter and peak acceleration is increased for upward versus downward arm movements. Muscle EMG activity and computational modeling have suggested that these kinematic asymmetries are generated because the brain uses gravity as a major force for acceleration during downward movements and for deceleration during upward movements. Here, we propose a basic set of experiments to examine whether vestibular (otolith) signals are functionally important for these properties. Thus, the aims of this application are two-fold. First, to ascertain whether macaques exhibit similar kinematic and EMG asymmetries during vertical arm movements as those observed in humans. Second, to examine whether the observed up/down asymmetries in arm movement kinematics and EMG depend on a functional vestibular labyrinth. We hypothesize (1) that macaques, like humans, show kinematic and EMG asymmetries during execution of up and down (as compared to horizontal) arm movements and (2) that an intact vestibular labyrinth is functionally important for detecting gravity and allowing for cost-effective planning of vertical arm movements. To achieve these goals, we will measure arm movement kinematics (Optotrak), as well as EMG activity from agonists and antagonists as monkeys execute center-out and center-in arm movements both in normal animals and after bilateral labyrinthectomy. To further examine whether there is any long term adaptation, we will be testing kinematics and EMG weekly for the first two months after labyrinthectomy. These experiments will be the first to directly investigate in macaques a potential role of gravity-related otolith signals on the planning and execution of arm movements. If successful, we will establish a solid behavioral context for a vestibular influence upon arm movements. Future neurophysiology studies can then explore how gravity- related vestibular signals are used for arm movement planning and execution.