Is there an optimal arm posture? Deterioration of finger localization precision and comfort sensation in extreme arm-joint postures
Is there an optimal arm posture? Deterioration of finger localization precision and comfort sensation in extreme arm-joint postures
复制标题
有没有最佳的手臂姿势？
DOI：
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发表时间：
2004
影响因子：
2
通讯作者：
C. Prablanc
中科院分区：
文献类型：
--
作者：
Y. Rossetti;C. Meckler;C. Prablanc
关节冗余的处理是电机控制中的重要问题之一。例如，凝视方向可以通过无限数量的眼睛和头部组合来获得。有人提出，解决这个问题的方法可能是最小化眼睛和头部的位置信号误差。对于自由度更大的手臂运动，提出了成本函数作为运动选择的标准，反映了一些由周围输入引起的舒适变量，例如最优肌肉能量消耗或葡萄糖消耗。然而，舒适性对运动控制的生物学意义尚未得到证实。我们进一步研究了这种方法，假设手臂姿势的选择也依赖于单个关节产生的位置信号误差的最小化。我们的预测是，对于目标手臂的舒适姿势，通过对侧手指指来定位指尖的准确性会提高，而对于使用极端关节姿势的不舒服姿势，则会降低。结果显示，当使用极端关节姿势（腕屈、肩举或两者）时，指向变异性增加。这种增加在指向可变性是成正比的增加主观不适评级。单个关节效应可以算术地加入到整个手臂值中，以获得不适感等级和指向变量和常数误差。这些结果表明，选择舒适的手臂姿势对应于手臂位置信号可靠性的优化。这一新的约束条件可能为进一步研究姿态或轨迹形成提供有用的工具。
Processing of joint redundancy is one of the most important problems in motor control. For instance, gaze orientation can be obtained with an infinite number of eye and head combinations. It has been proposed that a solution to this problem might be the minimization of eye and head position-signal errors. For arm movements, where the excess of degrees of freedom is even higher, cost function was proposed as a criterion for movement selection, reflecting some comfort variable evoked from the peripheral inputs, e.g. optimal muscular energy cost or glucose consumption. However, no biological implication of comfort on motor control has yet been demonstrated. We have further investigated this approach by hypothesizing that arm posture choice also relies on a minimization of position-signal errors arising from individual joints. The prediction is that accuracy of fingertip localization by pointing made by the contralateral hand would be enhanced for comfortable postures of the target arm and degraded for uncomfortable postures using extreme joint positions. Results show an increase in pointing variability when extreme joint postures are used (wrist flexion, shoulder elevation, or both). This increase in pointing variability is proportional to the increase in subjective discomfort rating. Individual joint effects can be added arithmetically into a whole arm value for both discomfort rating and pointing variable and constant error. These results suggest that the choice of comfortable postures for the arm corresponds to an optimization of arm positionsignal reliability. This new constraint might be a useful tool for further investigation on posture or trajectory formation.