IMPAIRMENTS OF REACHING MOVEMENTS IN PATIENTS WITHOUT PROPRIOCEPTION .1. SPATIAL ERRORS
IMPAIRMENTS OF REACHING MOVEMENTS IN PATIENTS WITHOUT PROPRIOCEPTION .1. SPATIAL ERRORS
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DOI：
10.1152/jn.1995.73.1.347
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发表时间：
1995-01-01
影响因子：
2.5
通讯作者：
GHEZ, C
中科院分区：
文献类型：
--
作者：
GORDON, J;GHILARDI, MF;GHEZ, C
1. 本文介绍了一系列研究，其中我们分析了因大纤维感觉神经病导致严重本体感觉缺陷的人类患者在平面到达任务中的损伤。我们研究了三名患者，他们都表现出上肢缺乏辨别性触觉、位置感和牵张反射。肌肉力量正常。我们将患者的伸手动作与正常对照组进行了比较。第一篇论文的目的是描述这些患者的空间错误，这些错误主要是由于运动计划和执行方面的缺陷而不是反馈控制方面的缺陷造成的。这是通过使用防止运动过程中错误的视觉反馈的任务来完成的。2。受试者被指示将手从给定的明星位置移动到水平数字化平板电脑上的不同目标。手的位置和目标显示在计算机屏幕上。受试者看不到自己的手，并且手部位置的屏幕显示在发出移动信号时变为空白。因此，运动过程中的视觉反馈无法用于实现准确性。每次试验后将运动路径显示为结果知识。 3．与对照组相比，患者在运动方向和范围上都存在较大的空间误差。方向错误从运动开始就很明显，表明它们是由于计划不当造成的。此外，患者的手部路径出现较大的弯曲和初次停止后的二次运动。4．患者使用的总体控制策略与对照组相同。手部轨迹近似钟形，运动范围通过缩放轨迹波形的幅度和时间来控制。然而，对照对象和患者在运动范围上都表现出系统误差，这取决于手部运动的方向。在对照受试者中，这些程度对方向的系统依赖性很小，但在患者中，它们产生了巨大且显着的错误。对手部轨迹的分析表明，误差与不同方向运动的速度和加速度的差异有关。5．在早期的研究中，我们表明，在具有正常感觉的受试者中，加速度和速度对方向的依赖性是由于在编程初始轨迹时未能考虑肢体的惯性特性而导致的。在对照受试者中，这些差异最初出现。加速度由运动时间的方向相关变化部分补偿。在患者中，不同方向运动的加速度和速度的变化与对照组相似，但患者的代偿变化比对照组要有限得多。6。在患者中始终可见的其他运动障碍，包括方向错误和大曲率，与惯性误差一样，都是在对照中看到的细微异常的夸大。它们显然是由于没有考虑到肢体复杂的生物力学特性而造成的。一些异常现象，例如二次运动的存在
1. This paper introduces a series of studies in which we analyze the impairments in a planar reaching task in human patients with severe proprioceptive deficits resulting from large-fiber sensory neuropathy. We studied three patients, all of whom showed absence of discriminative tactile sensation, position sense, and stretch reflexes in the upper extremities. Muscle strength was normal. We compared the reaching movements of the patients with those of normal control subjects. The purpose of this first paper was to characterize the spatial errors in these patients that result primarily from impairments in the planning and execution of movement rather than in feedback control. This was done by using a task in which visual feedback of errors during movement was prevented.2. Subjects were instructed to move their hand from given starring positions to different targets on a horizontal digitizing tablet. Hand position and targets were displayed on a computer screen. Subjects could not see their hand, and the screen display of hand position was blanked at the signal to move. Thus visual feedback during movement could not be used to achieve accuracy. Movement paths were displayed as knowledge of results after each trial.3. Compared with controls, the patients made large spatial errors in both movement direction and extent. Directional errors were evident from movement onset, suggesting that they resulted from improper planning. In addition, patients' hand paths showed large curves and secondary movements after initial stops.4. The overall control strategy used by patients appeared the same as that used by controls. Hand trajectories were approximately bell shaped, and movement extent was controlled by scaling a trajectory waveform in amplitude and rime. However, both control subjects and patients showed systematic errors in movement extent that depended on the direction of hand movement. In control subjects, these systematic dependencies of extent on direction were small, but in patients they produced large and prominent errors. Analysis of the hand trajectories revealed that errors were associated with differences in velocity and acceleration for movements in different directions.5. In an earlier study, we showed that in subjects with normal sensation that the dependence of acceleration and velocity on direction results from a failure to take the inertial properties of the limb into account in programming the initial trajectory. In control subjects, these differences in initial. acceleration are partially compensated by direction-dependent variations in movement rime. In patients, the variations-in acceleration and velocity for movements in different directions are similar to those seen in controls, but compensatory variations are much more limited in patients than in control subjects.6. Other movement impairments that are seen consistently in patients, including directional errors and large curvatures are, like inertial errors, exaggerations of subtle anomalies that also are seen in controls. They apparently result from a failure to take into account complex biomechanical properties of the limb. Some of the anomalies, such as the presence of secondary movements as well