Preliminary evidence of dynamic muscular synergies in human grasping

Motor synergies have been investigated since the 1980s as a simplifying paradigm of motor control by the nervous system. In particular, it is believed that they allow control of the highly redundant kinematic chain of the human hand by the central nervous system. Whereas so far the focus has been on kinematic synergies, that is common patterns in the motion of the hand and fingers, we hereby also investigate their dynamic aspect, evaluated through surface electromyography. We especially show that dynamic motor synergies exist, i.e., that muscles are activated synergistically; and that these synergies are largely comparable to one another across human subjects, even though surface electromyography is usually disturbed by muscle crosstalk, sweating, anatomical differences and inaccurate electrode positioning. If confirmed, these results would have applications, e.g., in control of advanced robotic hands.