Unpredictable elbow joint perturbation during reaching results in multijoint motor equivalence
Unpredictable elbow joint perturbation during reaching results in multijoint motor equivalence
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DOI：
10.1152/jn.00163.2011
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发表时间：
2011-09-01
影响因子：
2.5
通讯作者：
Scholz, J. P.
中科院分区：
文献类型：
--
作者：
Mattos, D. J. S.;Latash, M. L.;Scholz, J. P.
Mattos DJ，Latash ML，Park E，Kuhl J，Scholz JP。伸展过程中不可预测的肘关节扰动会导致多关节电机等值。神经生理学杂志106：1424-1436,2011。2011年6月15日首次出版；DOI：10.1152/jn.00163.2011。-运动等效性表达了这样一种想法，即运动部件在面临扰动时进行重组，以保持重要性能变量的值，例如手在伸展时的位置。引入了一种形式化的方法来定量评估这一概念：由于不可预测的肘部摄动而导致的关节构型的变化导致的性能变量的变化比给定关节构型变化的幅度要小。本研究调查了在整个运动轨迹中是否存在运动等效性，以及两种不同目标类型施加的限制对运动等效性的大小有何影响。受试者指向有或没有肘关节扰动的球形和圆柱形目标，这些扰动是由低或高刚度的弹性带产生的。受试者的手臂在初始位置被遮挡，扰动条件被随机化，以避免预测扰动或其大小。对非受控流形方法的一种改进的方差分析被用来研究受扰和非受扰试验中关节结构的变化(关节偏差向量)如何影响手的位置或方向。由扰动引起的运动等效性的证据从REACH开始就存在，并在REACH的40%之后随着扰动的强度而增加，随着REACH的进展变得更加突出。与三维位置相比，无论目标条件如何，关节结构中的马达等效项变化对手部方向的稳定性影响更大。结果与最近的神经控制模型一致，该模型允许灵活的关节协调模式，同时抵抗影响显著性能变量的方向上的关节配置偏差。这些观察结果也符合在电机层次结构的不同级别上定义参考配置的协同控制的一般方案。
Mattos DJ, Latash ML, Park E, Kuhl J, Scholz JP. Unpredictable elbow joint perturbation during reaching results in multijoint motor equivalence. J Neurophysiol 106: 1424-1436, 2011. First published June 15, 2011; doi: 10.1152/jn.00163.2011.-Motor equivalence expresses the idea that movement components reorganize in the face of perturbations to preserve the value of important performance variables, such as the hand's position in reaching. A formal method is introduced to evaluate this concept quantitatively: changes in joint configuration due to unpredictable elbow perturbation lead to a smaller change in performance variables than expected given the magnitude of joint configuration change. This study investigated whether motor equivalence was present during the entire movement trajectory and how magnitude of motor equivalence was affected by constraints imposed by two different target types. Subjects pointed to spherical and cylindrical targets both with and without an elbow joint perturbation produced by a low-or high-stiffness elastic band. Subjects' view of their arm was blocked in the initial position, and the perturbation condition was randomized to avoid prediction of the perturbation or its magnitude. A modification of the uncontrolled manifold method variance analysis was used to investigate how changes in joint configuration on perturbed vs. nonperturbed trials (joint deviation vector) affected the hand's position or orientation. Evidence for motor equivalence induced by the perturbation was present from the reach onset and increased with the strength of the perturbation after 40% of the reach, becoming more prominent as the reach progressed. Hand orientation was stabilized more strongly by motor equivalent changes in joint configuration than was three-dimensional position regardless of the target condition. Results are consistent with a recent model of neural control that allows for flexible patterns of joint coordination while resisting joint configuration deviations in directions that affect salient performance variables. The observations also fit a general scheme of synergic control with referent configurations defined across different levels of the motor hierarchy.