Ghez C, Sainburg R
Center for Neurobiology and Behavior, New York State Psychiatric Institute, College of Physicians and Surgeons, Columbia University, New York 10032, USA.
Can J Physiol Pharmacol. 1995 Feb;73(2):273-84. doi: 10.1139/y95-038.
This paper reviews a series of experiments comparing intact controls with functionally deafferented patients to determine the role of proprioception in controlling dynamic interactions between limb segments during movement. We examine the control of hand path in a planar movement-reversal task and in a familiar three-dimensional gesture with similar biomechanical characteristics. In the planar task subjects had to move their hand out and back along a series of straight-line segments in the horizontal plane without visual feedback. The lengths and directions of the target line segments were chosen to require different amounts of shoulder motion while requiring the same elbow excursion. In controls, hand paths were, as required, straight with sharp bends at the outermost point. In patients, however, distinctive errors appeared at movement reversals, consisting of widened hand paths resulting from desynchronization in the reversals of elbow and shoulder motions. These errors reflected an inability to program elbow muscle contractions in accord with interaction torques produced at the elbow by variations in acceleration of the shoulder. The reversal errors were substantially reduced after patients had practiced for a few trials while visually monitoring movements of their arm. The improvement was not limited to the direction where they had practiced with vision, but also extended to other directions in which the elbow torques were different. This suggests that practice with vision of the arm served to improve the general rules that subjects used to plan movement, rather than simply improving the performance of a specific response. Similar to their performance on the planar task, the patients made errors in interjoint coordination during unconstrained three-dimensional gestures with movement reversals. We conclude (i) that both the planning and the learning of movement required an internal model of the dynamic properties of the limb that takes account of interaction torques acting at different joints; (ii) that this internal model is normally established and updated using proprioceptive information; but (iii) that when proprioception is lacking, vision of the limb in motion partially substitutes for proprioception.
本文回顾了一系列实验，这些实验将完整对照组与功能去传入患者进行比较，以确定本体感觉在运动过程中控制肢体节段间动态相互作用的作用。我们研究了在平面运动反转任务和具有相似生物力学特征的熟悉三维手势中手部路径的控制。在平面任务中，受试者必须在没有视觉反馈的情况下，在水平面上沿着一系列直线段将手伸出并收回。目标线段的长度和方向被选择为需要不同量的肩部运动，同时需要相同的肘部偏移。在对照组中，手部路径按要求是直的，在最外点处有急转弯。然而，在患者中，运动反转时出现了明显的错误，表现为肘部和肩部运动反转不同步导致手部路径变宽。这些错误反映了无法根据肩部加速度变化在肘部产生的相互作用扭矩来编程肘部肌肉收缩。在患者通过视觉监测手臂运动进行几次试验练习后，反转错误大幅减少。这种改善不仅限于他们通过视觉练习的方向，还扩展到肘部扭矩不同的其他方向。这表明对手臂进行视觉练习有助于改进受试者用于计划运动的一般规则，而不仅仅是提高特定反应的表现。与他们在平面任务中的表现类似，患者在有运动反转的无约束三维手势中关节间协调也出现错误。我们得出结论：(i) 运动的计划和学习都需要一个考虑不同关节处相互作用扭矩的肢体动态特性内部模型；(ii) 这个内部模型通常使用本体感觉信息来建立和更新；但是 (iii) 当缺乏本体感觉时，运动中手臂的视觉部分替代了本体感觉。
