Variant and invariant features characterizing natural and reverse whole-body pointing movements
Variant and invariant features characterizing natural and reverse whole-body pointing movements
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DOI：
10.1007/s00221-012-3030-y
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发表时间：
2012-05-01
影响因子：
2
通讯作者：
Pozzo, Thierry
中科院分区：
文献类型：
--
作者：
Chiovetto, Enrico;Patane, Laura;Pozzo, Thierry
以前的研究表明，与沿重力方向的自然全身运动相关的运动学和肌肉活动呈现出编码相对于运动执行的运动计划和运动方案的特定方面的模块化组织。然而，目前尚不清楚这种模块化结构是否也是反向运动的特征，当需要大量关节的位移才能将整个身体恢复到站立的初始姿势。因此，为了研究运动方向逆转时哪些运动模式是保守的，主成分分析和非负矩阵分解分别被应用于描述与所有身体环节相关的仰角的时间演变的时间序列以及自然和反向全身运动的肌电信号。结果表明，仰角在时间上高度协变，尽管表征不同运动的全局参数有一些差异(表明与所选运动计划相关的高水平变量的差异)，但关节协变的水平不会随着运动方向的变化而改变。相比之下，正向全身指向任务的肌肉组织与反向动作的肌肉组织不同。这些结果与之前的发现一致，根据这一发现，中枢神经系统根据运动方向，利用不同的运动计划来执行全身运动。然而，除此之外，这项研究还展示了这样的运动计划如何转化为不同的肌肉策略，从而等同地确保关节空间的高度协变。
Previous investigations showed that kinematics and muscle activity associated with natural whole-body movements along the gravity direction present modular organizations encoding specific aspects relative to both the motor plans and the motor programmes underlying movement execution. It is, however, still unknown whether such modular structures characterize also the reverse movements, when the displacement of a large number of joints is required to take the whole body back to a standing initial posture. To study what motor patterns are conserved across the reversal of movement direction, principal component analysis and non-negative matrix factorization were therefore applied, respectively, to the time series describing the temporal evolution of the elevation angles associated with all the body links and to the electromyographic signals of both natural and reverse whole-body movements. Results revealed that elevation angles were highly co-varying in time and that despite some differences in the global parameters characterizing the different movements (indicating differences in high-level variable associated with the selected motor plans), the level of joint co-variation did not change across movement direction. In contrast, muscle organization of the forward whole-body pointing tasks was found to be different with respect to that characterizing the reverse movements. Such results agree with previous findings, according to which the central nervous system exploits, dependently on the direction of motion, different motor plans for the execution of whole-body movements. However, in addition, this study shows how such motor plans are translated into different muscle strategies that equivalently assure a high level of co-variation in the joint space.