Control of the wrist in three-joint arm movements to multiple directions in the horizontal plane
Control of the wrist in three-joint arm movements to multiple directions in the horizontal plane
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DOI：
10.1152/jn.2000.83.5.3188
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发表时间：
2000-05-01
影响因子：
2.5
通讯作者：
Nevoret-Bell, CJ
中科院分区：
文献类型：
--
作者：
Koshland, GF;Galloway, JC;Nevoret-Bell, CJ
在伸展运动中，腕关节受到近端关节运动的惯性影响。然而，手腕的精确控制对于达到准确性非常重要。对三关节手臂运动的研究表明，腕关节在点对点伸展过程中几乎没有移动，但尚未描述一系列运动方向上的肌肉活动和动力学。我们假设，为了最大限度地减少手腕运动，手腕处的肌肉扭矩必须完美抵消近端关节运动产生的惯性效应。受试者没有得到有关关节运动的指示，并且观察到受试者在从中心向外到达整个水平面的方向时保持手腕几乎不动。与此一致的是，与近端关节处的肌肉扭矩相比，腕部肌肉扭矩精确地反映了相互作用扭矩。这些发现表明，在这项伸手可及的任务中，神经系统选择通过预测动态惯性效应来最小化手腕运动。腕部肌肉：扭矩与肌肉的方向依赖性选择相关，其特征还在于最初的相互激活而不是最初的共同激活以使腕关节变硬。在第二个实验中，即使在腕关节固定的情况下进行多次试验后，相同的肌肉活动模式仍然持续存在。这些结果与三个关节的类似特征相结合，例如肌肉扭矩和跨方向肌肉起始的余弦调整，表明神经系统对每个关节的肌肉使用类似的规则，作为点对点伸展过程中手臂计划的一部分。
In a reaching movement, the wrist joint is subject to inertial effects from proximal joint motion. However, precise control of the wrist is important for reaching accuracy. Studies of three-joint arm movements report that the wrist joint moves little during point-to-point reaches, but muscle activities and kinetics have not yet been described across a range of movement directions. We hypothesized that to minimize wrist motion, muscle torques at the wrist must perfectly counteract inertial effects arising from proximal joint motion. Subjects were given no instructions regarding joint movement and were observed to keep the wrist nearly motionless during center-out reaches to directions throughout the horizontal plane. Consistent with this, wrist muscle torques exactly mirrored interaction torques, in contrast to muscle torques at proximal joints. These findings suggest that in this reaching task the nervous system chooses to minimize wrist motion by anticipating dynamic inertial effects. The wrist muscle: torques were associated with a direction-dependent choice of muscles, also characterized by initial reciprocal activation rather than initial coactivation to stiffen the wrist joint. In a second experiment, the same pattern of muscle activities persisted even after many trials reaching with the wrist joint immobilized. These results, combined with similar features at the three joints, such as cosine-like tuning of muscle torques and of muscle onsets across direction, suggest that the nervous system uses similar rules for muscles at each joint, as part of one plan for the arm during a point-to-point reach.