Differences between kinematic synergies and muscle synergies during two-digit grasping
Differences between kinematic synergies and muscle synergies during two-digit grasping
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DOI：
10.3389/fnhum.2015.00165
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发表时间：
2015-03-26
影响因子：
2.9
通讯作者：
Maier, Marc A.
中科院分区：
文献类型：
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作者：
Tagliabue, Michele;Ciancio, Anna Lisa;Maier, Marc A.
在抓握等实际运动中，手的大量机械自由度没有得到充分的利用。通常，不同关节的角度运动往往是耦合的，不同手部肌肉中的肌电活动往往是相互关联的。前者的协变称为运动学协同效应，后者的肌肉协同效应称为运动协同效应。这项研究解决了两个问题：(I)运动学和肌肉协同效应是否能够同时适应运动学和运动学约束。(Ii)如果有，运动学和肌肉协同作用之间是否存在相互关系。我们使用伸展-抓取-拉动范式，记录了手部运动学和8个表面肌电信号。受试者必须进行精确的抓握或侧向抓握，并必须改变他们的握力，以便在低或高负载下移动物体。分析被细分为三个时代：伸展、抓拉和静态握持。分别在运动学和肌电领域对所有三个时期进行主成分分析(PGA，时间或静态)。PGA显示：(1)运动学和肌肉协同效应可以同时适应运动学(抓握类型)和运动学任务约束(负载条件)。(2)抓握即将到来的握力和负荷条件体现在伸展过程中已经存在的运动学和肌肉协同效应中。主肌肉协同与主运动学协同的相平面图显示：(3)肌肉协同与前伸和抓举时的运动学协同相关联(相关，并同步推进)。此外(Iv)，握力过程中肌电的成对相关性表明，肌肉协同作用(部分)是通过共同输入的肌肉共同激活来实现的。综上所述，这些结果表明，运动学协同作用(至少部分地)不仅起源于肌肉激活，而且起源于协同肌肉激活。简而言之：运动学上的协同效应可能来自肌肉协同效应。
The large number of mechanical degrees of freedom of the hand is not fully exploited during actual movements such as grasping. Usually, angular movements in various joints tend to be coupled, and EMG activities in different hand muscles tend to be correlated. The occurrence of covariation in the former was termed kinematic synergies, in the latter muscle synergies. This study addresses two questions: (i) Whether kinematic and muscle synergies can simultaneously accommodate for kinematic and kinetic constraints. (ii) If so, whether there is an interrelation between kinematic and muscle synergies. We used a reach-grasp-and-pull paradigm and recorded the hand kinematics as well as eight surface EMGs. Subjects had to either perform a precision grip or side grip and had to modify their grip force in order to displace an object against a low or high load. The analysis was subdivided into three epochs: reach, grasp-and-pull, and static hold. Principal component analysis (PGA, temporal or static) was performed separately for all three epochs, in the kinematic and in the EMG domain. PGA revealed that (i) Kinematic- and muscle-synergies can simultaneously accommodate kinematic (grip type) and kinetic task constraints (load condition). (ii) Upcoming grip and load conditions of the grasp are represented in kinematic- and muscle-synergies already during reach. Phase plane plots of the principal muscle-synergy against the principal kinematic synergy revealed (iii) that the muscle-synergy is linked (correlated, and in phase advance) to the kinematic synergy during reach and during grasp-and-pull. Furthermore (iv), pair-wise correlations of EMGs during hold suggest that muscle-synergies are (in part) implemented by coactivation of muscles through common input. Together, these results suggest that kinematic synergies have (at least in part) their origin not just in muscular activation, but in synergistic muscle activation. In short: kinematic synergies may result from muscle synergies.