title: Kinematic analysis of the human wrist during pointing tasks.
abstract: In this work, we tested the hypothesis that intrinsic kinematic constraints such as Donders' law are adopted by the brain to solve the redundancy in pointing at targets with the wrist. Ten healthy subjects were asked to point at visual targets displayed on a monitor with the three dof of the wrist. Three-dimensional rotation vectors were derived from the orientation of the wrist acquired during the execution of the motor task and numerically fitted to a quadratic surface to test Donders' law. The thickness of the Donders' surfaces, i.e., the deviation from the best fitting surface, ranged between 1 degree and 2 degrees, for angular excursions from +/-15 degrees to +/-30 degrees. The results support the hypothesis under test, in particular: (a) Two-dimensional thick surfaces may represent a constraint for wrist kinematics, and (b) inter-subject differences in motor strategies can be appreciated in terms of curvature of the Donders' surfaces.
authors.affiliation: School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. d.campolo@ntu.edu.sg
authors.forename: Domenico
authors.initials: D
authors.lastname: Campolo
authors.forename: Domenico
authors.initials: D
authors.lastname: Formica
authors.forename: Eugenio
authors.initials: E
authors.lastname: Guglielmelli
authors.forename: Flavio
authors.initials: F
authors.lastname: Keller
mesh_terms: D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena / Q000502:physiology*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013647:Task Performance and Analysis; D014953:Wrist / Q000502:physiology*