functional synergies underlying control of upright posture during changes in head orientation潜在功能协同控制直立的姿势在头部方向的变化.pdfVIP

Functional Synergies Underlying Control of Upright Posture during Changes in Head Orientation 1 ¨ 2 1,3 Eunse Park , Gregor Schoner , John P. Scholz * ¨ 1 Biomechanics and Movement Science Program, University of Delaware, Newark, Delaware, United States of America, 2 Institute fur Neuroinformatik, Ruhr University, Bochum, Germany, 3 Physical Therapy Department, University of Delaware, Newark, Delaware, United States of America Abstract Background: Studies of human upright posture typically have stressed the need to control ankle and hip joints to achieve postural stability. Recent studies, however, suggest that postural stability involves multi degree-of-freedom (DOF) coordination, especially when performing supra-postural tasks. This study investigated kinematic synergies related to control of the body’s position in space (two, four and six DOF models) and changes in the head’s orientation (six DOF model). Methodology/Principal Findings: Subjects either tracked a vertically moving target with a head-mounted laser pointer or fixated a stationary point during 4-min trials. Uncontrolled manifold (UCM) analysis was performed across tracking cycles at each point in time to determine the structure of joint configuration variance related to postural stability or tracking consistency. The effect of simulated removal of covariance among joints on that structure was investigated to further determine the role of multijoint coordination. Results indicated that cervical joint motion was poorly coordinated with other joints to stabilize the position