Dounskaia Natalia, Nogueira Keith G, Swinnen Stephan P, Drummond Elizabeth
Department of Kinesiology, Arizona State University, P.O. Box 870404, Tempe, AZ 85287-0404, USA.
J Neurophysiol. 2010 Apr;103(4):2027-38. doi: 10.1152/jn.00778.2009. Epub 2010 Jan 13.
Studies of bimanual movements typically report interference between motions of the two arms and preference to perform mirror-symmetrical patterns. However, recent studies have demonstrated that the two arms differ in the ability to control interaction torque (INT). This predicts limitations in the capability to perform mirror-symmetrical movements. Here, two experiments were performed to test this prediction. The first experiment included bimanual symmetrical and asymmetrical circle drawing at two frequency levels. Unimanual circle drawing was also recorded. The increases in cycling frequency caused differences between the two arms in movement trajectories in both bimanual modes, although the differences were more pronounced in the asymmetrical compared with the symmetrical mode. Based on torque analysis, the differences were attributed to the nondominant arm's decreased capability to control INT. The intraarm differences during the symmetrical pattern of bimanual movements were similar (although more pronounced) to those during unimanual movements. This finding was verified in the second experiment for symmetrical bimanual oval drawing. Four oval orientations were used to provide variations in INT. Similar to the first experiment, increases in cycling frequency caused spontaneous deviations from perfect bimanual symmetry associated with inefficient INT control in the nondominant arm. This finding supports the limitations in performing mirror-symmetrical bimanual movements due to differences in joint control between the arms. Based on our results and previous research, we argue that bimanual interference occurs during specification of characteristics of required motion, whereas lower-level generation of muscle forces is independent between the arms. A hierarchical model of bimanual control is proposed.
对双手运动的研究通常报告称，双臂运动之间存在干扰，且倾向于执行镜像对称模式。然而，最近的研究表明，双臂在控制相互作用扭矩（INT）的能力上存在差异。这预示着执行镜像对称运动的能力存在局限性。在此，进行了两项实验来验证这一预测。第一个实验包括在两个频率水平上进行双手对称和不对称画圆。同时也记录了单手画圆。在两种双手模式下，循环频率的增加导致双臂在运动轨迹上存在差异，尽管与对称模式相比，不对称模式下的差异更为明显。基于扭矩分析，这些差异归因于非优势手臂控制INT的能力下降。双手对称运动模式下的手臂内差异与单手运动时相似（尽管更明显）。这一发现在第二个实验中得到了验证，该实验是关于双手对称画椭圆。使用了四种椭圆方向来提供INT的变化。与第一个实验类似，循环频率的增加导致与非优势手臂INT控制效率低下相关的对完美双手对称的自发偏离。这一发现支持了由于双臂关节控制差异而导致执行镜像对称双手运动存在局限性的观点。基于我们的研究结果和先前的研究，我们认为双手干扰发生在所需运动特征的指定过程中，而较低层次的肌肉力量产生在双臂之间是独立的。我们提出了一个双手控制的层次模型。
