VESTIBULAR INFLUENCES ON ARM MOVEMENTS

描述(由申请人提供)：我们想要进行一项关于前庭对手臂伸展运动的影响的新的研究。这项拟议的实验的动机是最近在人类受试者中发现的，上臂相对于下臂运动的路径曲率更大，加速持续时间更短，峰值加速度更大。肌肉肌电活动和计算模型表明，这些运动学不对称的产生是因为大脑使用重力作为向下运动时的加速和向上运动时的减速的主要力量。在这里，我们提出了一组基本的实验来检验前庭(耳石)信号是否在功能上对这些特性重要。因此，这一应用程序的目的有两个。首先，为了确定猕猴在垂直手臂运动过程中是否表现出与人类相似的运动学和肌电不对称。第二，检查观察到的手臂运动学和肌电上/下不对称是否依赖于功能性前庭迷路。我们假设(1)猕猴和人类一样，在执行上下(相对于水平)手臂运动时，表现出运动学和肌电的不对称；(2)完整的前庭迷宫对于检测重力和规划垂直手臂运动具有重要的功能。为了实现这些目标，我们将测量手臂运动运动学(Optotrak)，以及猴子在正常动物和双侧迷路切除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肌电活动。为了进一步检查是否有任何长期的适应，我们将在迷路切除后的前两个月每周测试运动学和肌电。这些实验将首次在猕猴身上直接研究与重力相关的耳石信号对手臂运动计划和执行的潜在作用。如果成功，我们将为前庭对手臂运动的影响建立坚实的行为背景。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计划和执行。

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.