title: Failure of Arm Movement Control in Stroke Patients, Characterized by Loss of Complexity.
abstract: We study the mechanism of human arm-posture control by means of nonlinear dynamics and quantitative time series analysis methods. Utilizing linear and nonlinear measures in combination, we find that pathological tremors emerge in patient dynamics and serve as a main feature discriminating between normal and patient groups. The deterministic structure accompanied with loss of complexity inherent in the tremor dynamics is also revealed. To probe the underlying mechanism of the arm-posture dynamics, we further analyze the coupling patterns between joints and components, and discuss their roles in breaking of the organization structure. As a result, we elucidate the mechanisms in the arm-posture dynamics of normal subjects responding to the gravitational force and for the reduction of the dynamic degrees of freedom in the patient dynamics. This study provides an integrated framework for the origin of the loss of complexity in the dynamics of patients as well as the coupling structure in the arm-posture dynamics.
authors.affiliation: Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: Segun
authors.initials: S
authors.lastname: Goh
authors.affiliation: Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: Kyungreem
authors.initials: K
authors.lastname: Han
authors.affiliation: Institute for Cognitive Science, College of Humanities, Seoul National University, Seoul 151-742, Korea.
authors.forename: Jehkwang
authors.initials: J
authors.lastname: Ryu
authors.affiliation: Department of Physical Education, Seoul National University, Seoul 151-748, Korea.
authors.forename: Seonjin
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: MooYoung
authors.initials: M
authors.lastname: Choi
mesh_terms: D000465:Algorithms; D001132:Arm / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D006801:Humans; D009068:Movement; D011187:Posture; D020521:Stroke / Q000503:physiopathology*