Dynamic coordination of body parts during prism adaptation.
We studied coordination across body parts in throwing during adaptation to prisms. Human subjects threw balls at a target before, during, and after wearing laterally shifting prism eyeglasses. Positions of head, shoulders, arm, and ball were video-recorded continuously. We computed body angles of eyes-in-head, head-on-trunk, trunk-on-arm, and arm-on-ball. In each subject, the gaze-throw adjustment during adaptation was distributed across all sets of coupled body parts. The distribution of coupling changed unpredictably from throw to throw within a single session. The angular variation among coupled body parts was typically significantly larger than angular variation of on-target hits. Thus coupled body parts changed interdependently to account for the high accuracy of ball-on-target. Principal components and Monte Carlo analyses showed variability in body angles across throws with a wide range of variability/stereotypy across subjects. The data support a model of a dynamic and generalized solution as evidenced by the distribution of the gaze-throw adjustment across body parts.
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D001696:Biomechanical Phenomena; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D010469:Perceptual Distortion / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*