Accuracy of internal dynamics models in limb movements depends on stability.
Accuracy of internal dynamics models in limb movements depends on stability.
复制标题
肢体运动内部动力学模型的准确性取决于稳定性。
DOI：
10.1007/s00221-004-1944-8
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发表时间：
2004
影响因子：
2
通讯作者：
Milner,TheodoreE
中科院分区：
文献类型：
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作者：
Milner,TheodoreE
本研究调查的能力，使用内部模型的环境动态时，动态是可预测的，但不稳定。受试者使用机器人操纵器进行目标导向的运动，同时抵消力场，力场通过与手的速度成比例地辅助运动而产生不稳定性。受试者在最后一次试验中的表现比第一次试验中的表现更好，在所有四个运动方向上进行测试：向外，向内，向右和向左。受试者适应力场主要是通过增加肌肉共同收缩，相比零场运动，在所有阶段的运动。在每个方向的前25次运动过程中，这种共收缩在减速和稳定阶段都普遍下降，但此后趋于不显著下降。在学习期结束时的捕捉试验表明，由于肌肉共同收缩而增加的粘弹性阻抗被用于抵消力场。只有在向外运动的情况下，观察到的后效与力场动力学的准确内部模型的形成是一致的。稳定的手向外运动需要较少的肌肉共同收缩比其他方向的运动，由于稳定性赋予的几何形状的arm.The结果表明，内部模型的准确性严重依赖于稳定的肢体和环境的耦合动力学。
This study investigated the ability to use an internal model of the environmental dynamics when the dynamics were predictable but unstable. Subjects performed goal-directed movements using a robot manipulandum while counteracting a force field, which created instability by assisting the movement in proportion to hand velocity. Subjects’ performance was better on the last trial than on the first trial in the force field for all four movement directions tested: out, in, right and left. Subjects adapted to the force field primarily by increasing muscle co-contraction, compared to null field movements, during all phases of movement. This co-contraction generally declined for both the deceleration and stabilization phases during the course of the first 25 movements in each direction, but tended not to decrease significantly thereafter. Catch trials at the end of the learning period suggested that increased viscoelastic impedance due to muscle co-contraction was used to counteract the force field. Only in the case of outward movements were aftereffects observed that were consistent with formation of an accurate internal model of the force field dynamics. Stabilization of the hand for outward movements required less muscle co-contraction than for movements in other directions due to stability conferred by the geometry of the arm. The results suggest that the accuracy of an internal model depends critically on the stability of the coupled dynamics of the limb and the environment.