UFR-STAPS, INSERM U-1093, Cognition, Action and Sensorimotor Plasticity Université de Bourgogne, Campus Universitaire, Dijon, France.
PLoS One. 2013;8(1):e52477. doi: 10.1371/journal.pone.0052477. Epub 2013 Jan 14.
Our aim was to investigate how the organization of a whole body movement is altered when movement duration (MD) is varied. Subjects performed the same whole body pointing movement over long, normal and short MDs. The kinematic trajectories were then analyzed on a normalized time base. A principal components analysis (PCA) revealed that the degree of coordination between the elevation angles of the body did not change with MD. This lack of significant differences in the coordination was interesting given that small spatial and temporal differences were observed in the individual kinematic trajectories. They were revealed by studying the trajectories of the elevation angles, joint markers and center of mass. The elevation angle excursions displayed modifications primarily in their spatial characteristics. These alterations were more marked for the short rather than long duration movements. The temporal characteristics of the elevation angles as measured by the time to peak of angular velocity were not modified in the same fashion hence displaying a dissociation in the tuning of the spatial and temporal aspects of the elevation angles. Modifications in the temporal characteristics of the movement were also studied by examining the velocity profiles of the joint markers. Interestingly, unlike the disordered nature of this variable for the elevation angles, the time to peak velocity was neatly ordered as a function of MD for the joint markers - It arrived first for the short duration movements, followed by those of the normal and finally long duration movements. Despite the modifications observed in the kinematic trajectories, a PCA with the elevation angle excursions at different MDs revealed that two principal components were sufficient to account for nearly all the variance in the data. Our results suggest that although similar, the kinematic trajectories at different MDs are not achieved by a simple time scaling.
我们的目的是研究当运动持续时间（MD）变化时，整个身体运动的组织是如何改变的。受试者在长、正常和短 MD 下执行相同的全身指向运动。然后在归一化时间基础上分析运动轨迹。主成分分析（PCA）表明，身体升高角度之间的协调程度不会随 MD 而改变。鉴于在个体运动轨迹中观察到小的空间和时间差异，但协调上没有明显差异，这一点很有趣。通过研究升高角度、关节标记和质心的轨迹来揭示这些差异。升高角度的摆动显示出主要在其空间特征方面的修改。这些变化在短运动而不是长运动中更为明显。由角速度峰值时间测量的升高角度的时间特征没有以相同的方式进行修改，因此显示出升高角度的空间和时间方面的调谐的分离。还通过检查关节标记的速度曲线来研究运动的时间特征的变化。有趣的是，与升高角度的这个变量的无序性质不同，关节标记的峰值速度时间作为 MD 的函数整齐地排列 - 对于短持续时间运动首先到达，然后是正常持续时间运动，最后是长持续时间运动。尽管观察到运动轨迹的变化，但在不同 MD 下的升高角度的 PCA 表明，两个主成分足以解释数据中的几乎所有方差。我们的结果表明，尽管相似，但不同 MD 下的运动轨迹不是通过简单的时间缩放来实现的。
