Oct 23, 2004 - Presentation Number: 68.4. Abstract Title: Kinetics and kinematics of reaching during encoded and unencoded torso rotations which generate.
Neuroscience 2004 Abstract Presentation Number:
68.4
Abstract Title:
Kinetics and kinematics of reaching during encoded and unencoded torso rotations which generate coriolis forces.
Authors:
Pierobon, A.*1 ; Bortolami, S. B.1 ; Pigeon, P.1 ; DiZio, P.1 ; Lackner, J. R.1 1 Ashton Graybiel Lab., Brandeis Univ., Waltham, MA
Primary Theme and Topics
Motor Systems - Kinematics and EMG -- Reaching and pointing Motor Systems - Kinematics and EMG -- Reflexes 68. Kinematics and EMG: Reaching and Pointing I Poster Saturday, October 23, 2004 4:00 PM-5:00 PM Convention Center Exhibit Hall, Poster Board V25 motor control, computer model, human, sensorymotor
Secondary Theme and Topics
Session: Presentation Time: Location: Keywords:
We compared 7 subjects who made fast and slow paced turn and reach (T&R) movements in a stationary environment and 3 subjects who reached during 20 rpm CCW rotation in an enclosed slow rotation room (SRR). All movements were executed in complete darkness with the right arm. SRR movements were aimed at a target ~35 cm straight ahead on the body midline, and T&R movements at a target 56 cm away and 105˚ left of the midline. The T&R target elicited ~60˚ active torso rotation during arm extension; SRR movements involved comparable arm extension during passive constant velocity rotation which the semicircular canals can not encode. An OPTOTRAK recorded kinematics. Joint torques were computed with a new inverse dynamics model which separates the torque associated with arm motion re torso from torques due to torso rotation (Coriolis) and translation. Subjects always felt stationary when reaching in the SRR. Initial SRR reaches were significantly deviated rightward by Coriolis forces. Straight and accurate trajectories were restored after 48 reaches during rotation. Adapted reaches at 20 rpm generated significant Coriolis torques, but the torso-relative torques were not greater than pre-rotation. Fast T&R movements generated more than twice the Coriolis torque of slow T&R movements, yet the curvatures and endpoints of the fast and slow movements did not differ. Fast T&R movements also generated larger Coriolis torques than adapted reaches at 20 rpm in the SRR, yet initial reaches in the SRR were significantly deviated whereas T&R movements were not. This pattern means the execution plan for voluntary T&R movements incorporates compensation for Coriolis torques on the arm due to torso rotation, and that Coriolis compensation requires encoding of torso rotation speed. By means of our model we can now compare unconstrained reaches across paradigms and conditions. Supported by NASA NAG9-1466 and NIH RO1AR48546-01.
