Limb dominance results from asymmetries in predictive and impedance control mechanisms.
Limb dominance results from asymmetries in predictive and impedance control mechanisms.
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DOI：
10.1371/journal.pone.0093892
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Sainburg RL
中科院分区：
文献类型：
--
作者：
Yadav V;Sainburg RL
利手是人类运动行为的一个显著特征，但其潜在的神经机制仍不清楚。我们假设运动偏侧化是由于任务动力学的预测控制和肢体阻抗控制的不对称性造成的。为了验证这一假设，我们提供了两种不同的力场环境的实验，一个场的可预测幅度随速度的平方变化，而另一个场的幅度较小，随速度线性变化。这些场被设计成与控制器兼容，这些控制器专门用于预测肢体和任务动态，以及分别调制位置和速度相关的阻抗。由于速度平方场不改变到达臂的运动方程的形式，我们认为前馈动态型控制器在这一场中应该表现良好，而线性阻尼项和刚度项的控制应该不那么有效。相反，不可预测的线性场应该与阻抗控制最兼容，但与预测动态控制不兼容。我们测量了暴露在这些场中的稳态最终位置精度和3个轨迹特征：均方挺度、直线度和运动时间。我们的结果证实，每只手臂在其相容的视野中都能做出更直、更流畅、更快的动作。两只手臂都表现出相似的最终位置精确度，当其中一只手臂在不相容的场地中表演时，通过更广泛的矫正子运动实现了这一点。最后，每个手臂对其不相容的领域表现出有限的适应。对轨迹误差对场大小的依赖分析表明，优势臂的适应是通过预测平均场发生的，从而利用了预测机制来适应不可预测的场。总体而言，我们的结果支持这一假设，即运动偏侧化反映了特定运动控制机制中的不对称性，这些机制与肢体和任务动力学的预测控制以及肢体阻抗的调节有关。
Handedness is a pronounced feature of human motor behavior, yet the underlying neural mechanisms remain unclear. We hypothesize that motor lateralization results from asymmetries in predictive control of task dynamics and in control of limb impedance. To test this hypothesis, we present an experiment with two different force field environments, a field with a predictable magnitude that varies with the square of velocity, and a field with a less predictable magnitude that varies linearly with velocity. These fields were designed to be compatible with controllers that are specialized in predicting limb and task dynamics, and modulating position and velocity dependent impedance, respectively. Because the velocity square field does not change the form of the equations of motion for the reaching arm, we reasoned that a forward dynamic-type controller should perform well in this field, while control of linear damping and stiffness terms should be less effective. In contrast, the unpredictable linear field should be most compatible with impedance control, but incompatible with predictive dynamics control. We measured steady state final position accuracy and 3 trajectory features during exposure to these fields: Mean squared jerk, Straightness, and Movement time. Our results confirmed that each arm made straighter, smoother, and quicker movements in its compatible field. Both arms showed similar final position accuracies, which were achieved using more extensive corrective sub-movements when either arm performed in its incompatible field. Finally, each arm showed limited adaptation to its incompatible field. Analysis of the dependence of trajectory errors on field magnitude suggested that dominant arm adaptation occurred by prediction of the mean field, thus exploiting predictive mechanisms for adaptation to the unpredictable field. Overall, our results support the hypothesis that motor lateralization reflects asymmetries in specific motor control mechanisms associated with predictive control of limb and task dynamics, and modulation of limb impedance.
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