COMPENSATORY ARM-TRUNK COORDINATION IN POINTING MOVEMENTS IS PRESERVED IN THE ABSENCE OF VISUAL FEEDBACK

This study examined the influence of trunk recruitment on the kinemati c characteristics of pointing movements. The distribution of final pos itions of the hand, the extent and direction of the hand trajectory wa s basically preserved when trunk movement was combined with arm pointi ng. These effects were observed during pointing not only with but also without vision. The results imply that two functionally independent u nits of coordination are used in pointing regardless of visual feedbac k-one producing arm movement to the target (the reaching synergy) and the other coordinating trunk and arm movements diminishing the influen ce of the trunk on the arm endpoint trajectory (the compensatory syner gy). (C) 1998 Elsevier Science B.V. All rights reserved.