HEAD CONTROL MECHANISMS DURING VOLUNTARY TRUNK MOVEMENTS

这个项目的目的是确定意向机制如何 有助于在俯仰(矢状)平面内保持头部稳定 完好无损和双侧躯干自愿性活动 前庭(BVL)系统受损。一组研究将量化 反射和反射之外的意向机制的贡献 机械加工。第二组研究将评估 不同类型的意向策略被用来稳定头部。 不同的条件。经验和计算机建模方法将 检验意向机制显著贡献的假设 在BVL和完好的受试者中领导稳定，并且 这些群体使用不同类型的战略来稳定他们的 头朝上。在经验性研究中，受试者将坐在雪橇上 在前后方向上平移。他们会自愿 用手持操纵杆控制雪橇的平移，并有一些 强加在他们身上的雪橇运动。雪橇的平移产生作用力 这会破坏头部在俯仰面上的稳定性。头部运动的分析 扭矩和颈部和躯干的肌电活动 肌肉将揭示受试者如何很好地抵消破坏头部稳定的 雪橇平移过程中的力量。这些数据还将揭示出 受试者通过避免干扰来稳定他们的头部(减少 后备箱主题运动)，预期和预测性地取消 扰乱，通过肌肉协同收缩使脖子僵硬，或者 依靠反射和被动力学。一种分析模型 头颈部控制系统将用于运行模拟，以 确定意向机制对Head有多大作用 稳定，这将建立如何故意的组合， 机械和反射策略可以共同作用，以稳定 头。 该项目是第一个对意向性稳定头部进行评估的项目 在自愿的躯干移动过程中的机制。该项目还将增加 通过评估意向性来了解头部控制机制的基础知识 自愿流动期间的流程，类似于 日常生活，通常涉及自愿而不是强加的行动 后备箱的。完整种群和BVL种群的比较将 解释为什么一些BVL患者恢复了相对较高的功能 水平，而其他人不是。

The aim of this project is to determine how intentional mechanisms contribute to head stabilization in the pitch (sagittal) plane during voluntary trunk movements in persons with intact and bilaterally impaired vestibular (BVL) systems. One set of studies will quantify the contributions made by intentional mechanisms beyond reflex and mechanical processes. A second set of studies will evaluate what subtypes of intentional strategies are used to stabilize the head under different conditions. Empirical and computer modeling approaches will test the hypotheses that intentional mechanisms contribute significantly to head stabilization in the BVL as well as intact subject, and that these groups use different subtypes of strategies to stabilize their heads. In the empirical studies, subjects will sit on a sled that can translate in the anterior-posterior direction. They will voluntarily control translation of the sled by a hand-held joystick, and have some sled motions imposed on them. The sled translations generate forces that destabilize the head in the pitch plane. Analyses of head motion and torques and of electromyographic activity in the neck and trunk muscles will reveal how well subjects counteract the head-destabilizing forces during sled translation. The data also will reveal whether subjects stabilize their heads by avoiding the disturbance (reducing trunk subjects motion), anticipating and predictively cancelling the disturbance, by stiffening their neck through muscle cocontraction, or by relying on reflexes and passive mechanics. An analytical model of the head-neck control system will be used to run simulations that will determine how much intentional mechanisms contribute to head stabilization, and that will establish how combinations of intentional, mechanical and reflex strategies could work together to stabilize the head. This project is the first to evaluate intentional head-stabilizing mechanisms during voluntary trunk movements. The project also will add to basic knowledge of head control mechanisms by evaluating intentional processes during voluntary movements that are similar to activities of daily life, which generally involve voluntary rather than imposed motion of the trunk. The comparison of intact and BVL populations will elucidate why some persons with BVL recover relatively high functional levels, and others do not.