TRAJECTORY SPECIFICATION IN TARGETED LIMB MOVEMENT

我们的长期目标是进一步了解 使我们能够快速移动四肢的神经过程， 准确地定位到我们周围的目标， 感觉障碍和小脑损害患者的准确性 辨距障碍 我们也希望设计出有效的方法来改善 这类患者的运动表现。 我们的方法是分析 详细描述一个简单的运动任务的表现， 神经系统控制的基本原理 肌肉骨骼系统 目前的建议是， 本报告所述期间完成的工作， 产生简单的等长反应。 首先，我们计划 确定目标响应的幅度和方向如何 使用从目标导出的信息指定。 问题是 使用一种新的实验程序来解决， 从刺激到反应间隔可以系统地变化。 其次，我们计划确定控制策略的差异 用于产生力和位置轨迹， 受试者面临不同的负荷条件。 特别 注意力集中在惯性载荷的减速问题上 对对手发出精确的定时指令 第三，我们计划 分析患者的轨迹形成障碍， 严重的感觉神经病变 初步观察结果 患者表示，不准确的性能是由于 对轨迹参数进行编程的能力也受到损害 由于无法有效利用内部反馈， 纠正初始轨迹误差的机制。 提出 实验将使用听觉线索来代替丢失的 本体感受信息，以提高准确性， 更新中。 第四，我们将启动小脑辨距障碍的研究 以确定造成不准确的机制， 这类患者表现出的运动开始延迟。

Our long term objectives are to gain further understanding of the neural processes that enable us to move our limbs rapidly and accurately to targets around us and to explain the disordered accuracy of patients with sensory impairment and cerebellar dysmetria. We also hope to devise effective methods for improving motor performance in such patients. Our approach is to analyze in detail the performance of a simple motor task to uncover fundamental principles by which the nervous system controls the musculoskeletal system. The present proposal extends work accomplished in the current period that was focused exclusively on the production of simple isometric responses. First, we plan to determine how the amplitude and direction of an aimed response are specified using information derived from a target. The problem is addressed using a new experimental procedure by which the time interval from stimulus to response can be varied systematically. Second, we plan to determine the differences in control strategies used for the producing force and position trajectories when subjects are faced with different loading conditions. Particular attention is given to the problem of decelerating inertial loads using accurately timed commands to antagonists. Third, we plan to analyze the disorders in trajectory formation of patients with severe sensory neuropathies. Preliminary observations in two patients indicate that inaccurate performance results from impairment in the ability to program trajectory parameters as well as from an inability to make effective use of internal feedback mechanisms to correct initial trajectory errors. Proposed experiments will use auditory cues to substitute for the lost proprioceptive information in order to improve accuracy and updating. Fourth, we will initiate a study of cerebellar dysmetria to determine the mechanisms responsible for the inaccuracy and the delays in movement initiation shown by such patients.