Influence of disturbances on the control of PC-mouse, goal-directed arm movements

This study concerns the influence of visuomotor rotating disturbance on motion dynamics and brain activity. It involves using a PC-mouse and introducing a predefined bias angle between the direction of motion of the mouse pointer and that of the screen cursor. Subjects were asked to execute three different tasks, designed to study the effect of visuomotor rotation on direction control, extent control or the two together. During each task, mouse movement, screen cursor movement and electroencephalograph (EEG) signals were recorded. An algorithm was used to detect and discard EEG signals contaminated by artifacts. Movement performance indexes and brain activity are used to evaluate motion control, tracking ability, learning and control. The results suggest the direction control is planned before the movement and controlled by an adaptive control while extent control is controlled by a real-time feedback. The measurements also confirm that increased motion and/or brain activity occur for bias angles in the ranges ±(90-120°) for both direction and extension controls. After-effects when changing the angle of visual rotation have been seen to be proportional to the variation in the adaptation angle.