%0 Journal Article
%T Learning Arm/Hand Coordination with an Altered Visual Input
%A Simona Denisia Iftime Nielsen
%A Strahinja Do£¿en
%A Mirjana B. Popovi£¿
%A Dejan B. Popovi£¿
%J Computational Intelligence and Neuroscience
%D 2010
%I Hindawi Publishing Corporation
%R 10.1155/2010/520781
%X The focus of this study was to test a novel tool for the analysis of motor coordination with an altered visual input. The altered visual input was created using special glasses that presented the view as recorded by a video camera placed at various positions around the subject. The camera was positioned at a frontal (F), lateral (L), or top (T) position with respect to the subject. We studied the differences between the arm-end (wrist) trajectories while grasping an object between altered vision (F, L, and T conditions) and normal vision (N) in ten subjects. The outcome measures from the analysis were the trajectory errors, the movement parameters, and the time of execution. We found substantial trajectory errors and an increased execution time at the baseline of the study. We also found that trajectory errors decreased in all conditions after three days of practice with the altered vision in the F condition only for 20 minutes per day, suggesting that recalibration of the visual systems occurred relatively quickly. These results indicate that this recalibration occurs via movement training in an altered condition. The results also suggest that recalibration is more difficult to achieve for altered vision in the F and L conditions compared to the T condition. This study has direct implications on the design of new rehabilitation systems. 1. Introduction Visual information plays an important role in both planning and executing goal-directed movements. When planning the reaching aspect of the ¡°reach to grasp movement,¡± vision provides information about the object¡¯s properties (shape, size, and position in space) as described in detail many years ago by Jeannerod [1]. During the execution of the action, the proprioceptive system (muscle spindles, Golgi tendon organs, and joint receptors) sends information to the central nervous system, which is then used for estimation of the accuracy of the execution. In parallel, vision provides feedback, which allows corrections if they are required [2]. The performance depends on the level of mastery in executing the movement that follows the learning. The role of vision during reaching to grasp was studied in detail by either preventing the subject from viewing either only the hand or both the object and the hand during movement (this is often referred to as visual open loop; e.g., [3¨C5]). The results of previous studies agree that preventing vision during the reaching movement affects movement parameters (i.e., hand-target distance at the initiation of aperture closure, grip aperture amplitude, wrist velocity, and
%U http://www.hindawi.com/journals/cin/2010/520781/