%0 Journal Article %1 Robertson:1997 %A Robertson, E M %A Miall, R C %D 1997 %J Experimental Brain Research %K Double-step Human Inverse Key On-line Pointing control kinematics stimulation words ´ %P 148-152 %T Multi-joint limbs permit a flexible response to unpredictable events %V 117 %X Abstract The human arm is kinematically redundant, which may allow flexibility in the execution of reaching movements. We have compared reaching movements with and without kinematic redundancy to unpredictable double-step targets. Subjects sat in front of a digitising tablet and were able to view an arc of four targets reflected in the mirror as virtual images in the plane of the tablet. They were instructed to move, from a central starting point, in as straight a line as possible to a target. In onethird of trials, the target light switched to one of its neighbours during the movement. Subjects made 60 movements using shoulder, elbow and wrist and then another 60 movements in which only shoulder and elbow movement were allowed. By restraining the wrist, the limb was made non-redundant. The path length was calculated for each movement. In single-step trials, there was no significant difference between path lengths performed with and without wrist restraint. As expected there was a significant increase in path length during double-step trials. Moreover this increase was significantly greater when the wrist was restrained. The variability across both single- and double-step movements was significantly less while the wrist was restrained. Importantly the performance time of the movements did not alter significantly for single-step, double-step or restrained movements. These results suggest that the nervous system exploits the intrinsic redundancy of the limb when controlling voluntary movements and is therefore more effective at reprogramming movements to double-step targets.

@article{Robertson:1997, abstract = {Abstract The human arm is kinematically redundant, which may allow flexibility in the execution of reaching movements. We have compared reaching movements with and without kinematic redundancy to unpredictable double-step targets. Subjects sat in front of a digitising tablet and were able to view an arc of four targets reflected in the mirror as virtual images in the plane of the tablet. They were instructed to move, from a central starting point, in as straight a line as possible to a target. In onethird of trials, the target light switched to one of its neighbours during the movement. Subjects made 60 movements using shoulder, elbow and wrist and then another 60 movements in which only shoulder and elbow movement were allowed. By restraining the wrist, the limb was made non-redundant. The path length was calculated for each movement. In single-step trials, there was no significant difference between path lengths performed with and without wrist restraint. As expected there was a significant increase in path length during double-step trials. Moreover this increase was significantly greater when the wrist was restrained. The variability across both single- and double-step movements was significantly less while the wrist was restrained. Importantly the performance time of the movements did not alter significantly for single-step, double-step or restrained movements. These results suggest that the nervous system exploits the intrinsic redundancy of the limb when controlling voluntary movements and is therefore more effective at reprogramming movements to double-step targets.}, added-at = {2009-06-26T15:25:19.000+0200}, author = {Robertson, E M and Miall, R C}, biburl = {https://www.bibsonomy.org/bibtex/2c25b8c521e68184f64d2119c6cf1e7d6/butz}, description = {diverse cognitive systems bib}, interhash = {099c96061ae05b9e500489b229fa7d91}, intrahash = {c25b8c521e68184f64d2119c6cf1e7d6}, journal = {Experimental Brain Research}, keywords = {Double-step Human Inverse Key On-line Pointing control kinematics stimulation words ´}, owner = {Olli}, pages = {148-152}, review = {Movents were made with - Constrained wrist or unconstrained (redundant) - With target displacements during movement or without -> Unconstraint Sc can respond to sudden changes with shorter pathlength and higher movement variability than constrained subjects -> There was no big difference betwee cons and unconstraint Ss during single step (no displacement) trials}, timestamp = {2009-06-26T15:25:53.000+0200}, title = {Multi-joint limbs permit a flexible response to unpredictable events}, volume = 117, year = 1997 }