Department of Kinesiology, University of Maryland, College Park, MD 20742, USA.
J Biomech. 2010 Aug 26;43(12):2249-53. doi: 10.1016/j.jbiomech.2010.04.033. Epub 2010 May 21.
This study investigated synergistic actions of hand-pen contact forces during circle drawing tasks in three-dimensional (3D) space. Twenty-four right-handed participants drew thirty concentric circles in the counterclockwise (CCW) and clockwise (CW) directions. Three-dimensional forces acting on an instrumented pen as well as 3D linear and angular positions of the pen were recorded. These contact forces were then transformed into the 3D radial, tangential, and normal force components specific to circle drawing. Uncontrolled manifold (UCM) analysis was employed to calculate the magnitude of the hand-pen contact force synergy. Three hypotheses were tested. First, hand-pen contact force synergies during circle drawing are dependent on the angular position of the pen tip. Second, hand-pen contact force synergies are dependent on force components in circle drawing. Third, hand-pen contact force synergies are greater in CCW direction than CW direction. The results showed that the strength of the hand-pen contact force synergy increased during the initial phase of circle drawing and decreased during the final phase. The synergy strength was greater for the radial and tangential components as compared to the normal component. Also, the circle drawing in CW direction was associated with greater hand-pen contact force synergy than the CCW direction. The results of this study suggest that the central nervous system (CNS) prioritizes hand-pen contact force synergies for the force components (i.e., radial and tangential) that are critical for circle drawing. The CNS modulates hand-pen contact force synergies for preparation and conclusion of circle drawing, respectively.
本研究探讨了在三维（3D）空间中进行圆绘制任务时手动笔接触力的协同作用。24 名右利手参与者逆时针（CCW）和顺时针（CW）方向绘制了三十个同心圆。记录了作用在仪器化笔上的三维力以及笔的三维线性和角位置。然后，将这些接触力转换为特定于圆绘制的三维径向、切向和法向力分量。采用非控制流形（UCM）分析来计算手笔接触力协同的大小。测试了三个假设。首先，圆绘制过程中手笔接触力协同取决于笔尖的角度位置。其次，手笔接触力协同取决于圆绘制中的力分量。第三，手笔接触力协同在 CCW 方向比 CW 方向更大。结果表明，在圆绘制的初始阶段，手笔接触力协同的强度增加，在最终阶段下降。与正常分量相比，协同强度径向和切向分量更大。此外，CW 方向的圆绘制比 CCW 方向的圆绘制具有更大的手笔接触力协同。本研究的结果表明，中枢神经系统（CNS）优先考虑手笔接触力协同，以适应圆绘制的力分量（即径向和切向）。CNS 分别为圆绘制的准备和完成调节手笔接触力协同。
