caa a22 4500 445354216 CHVBK 20180317142854.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s00221-010-2493-y doi (NATIONALLICENCE)springer-10.1007/s00221-010-2493-y Joint angle variability and co-variation in a reaching with a rod task [Elektronische Daten] [M. (Marieke) van der Steen, Raoul Bongers] The problem at the heart of motor control is how the myriad units of the neuromotor system are coordinated to perform goal-directed movements. Although for long these numerous degrees of freedom (DOFs) were considered redundant, recent views emphasize more that the DOFs should be considered abundant, allowing flexible performance. We studied how variability in arm joints was employed to stabilize the displaced end-effector in tool use to examine how the neuromotor system flexibly exploits DOFs in the upper extremity. Participants made pointing movements with the index finger and with the index finger extended by rods of 10, 20, and 30cm. Using the uncontrolled manifold (UCM) method, the total joint angle variance was decomposed into two parts, the joint angle variance that did not affect the position of the end-effector (V UCM) and the variance that results in a deviation of the position of the end-effector from its mean (V ORT). Analyses showed that some angles depended on length of the rod in use. For all rod lengths, V UCM was larger than V ORT, and this did not differ over rod lengths, demonstrating that the arm was organized into a synergy. Finally, the variation in the joint angles in the arm as well as the degree of co-variation between these angles did not differ for the rod's tip and the hand. We concluded that synergies are formed in the arm during reaching with an extended end-effector and those synergies stabilize different parts of the arm+rod system equally. The Author(s), 2010 Synergy nationallicence Uncontrolled manifold (UCM) nationallicence Joint variability nationallicence Motor coordination nationallicence Tool use nationallicence Reaching nationallicence van der Steen M. (Marieke) Marieke Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, P.O. Box 196, 9700 AD, Groningen, The Netherlands aut Bongers Raoul Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, P.O. Box 196, 9700 AD, Groningen, The Netherlands aut Experimental Brain Research Springer-Verlag 208/3(2011-02-01), 411-422 0014-4819 208:3<411 2011 208 221 https://doi.org/10.1007/s00221-010-2493-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00221-010-2493-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- van der Steen M. (Marieke) Marieke Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, P.O. Box 196, 9700 AD, Groningen, The Netherlands aut NATIONALLICENCE 700 1- Bongers Raoul Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, P.O. Box 196, 9700 AD, Groningen, The Netherlands aut NATIONALLICENCE 773 0- Experimental Brain Research Springer-Verlag 208/3(2011-02-01), 411-422 0014-4819 208:3<411 2011 208 221 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer