EFFECT OF VIDEO FEEDBACK ON THE PERFORMANCE OF A WEIGHT SHIFTING CONTROLLED TRACKING TASK IN SUBJECTS WITH PARKINSONISM AND NEUROLOGICALLY INTACT INDIVIDUALS

This study compared the performance of a visual motor task, accomplished by standing weight shifting, of 34 people with Parkinson's disease (P.D.) and 34 neurologically intact (N.I.) subjects. Twenty of the P.D. subjects were in Stage 1 and 14 were in Stage 2. The performance of ten, 10-s trials was each examined under two feedback (FB) conditions: continuous video display of performance and end of trial position. Visual FB was composed of displaying a target and cursor on a video monitor, with the cursor controlled by the subject through weight shifting on a platform interfaced with a microprocessor. Once the cursor was centered, the computer then transferred the target to the upper right quadrant of the monitor, and the subject was required, through weight shifting, to relocate the cursor inside the target. ANOVA with repeated measures was used for data analysis. The visual motor performance of P.D. subjects was significantly worse than that of N.I. (P < 0.01), as well as between FB conditions (P < 0.01). The interaction of the FB condition by trial segment was significant (P < 0.01), as was the interaction of group membership by the trial segment (P < 0.01). FB condition and group membership did not significantly interact, confirming that performance was worse under end of trial position FB, regardless of group membership (P < 0.01). Post hoc analysis yielded significant differences (P < 0.05) in task performance between N.I. and P.D. subjects after the first second of the trials regardless of FB condition. In either group, significant differences between continuous visual FB and end of trial position FB (P < 0.05) were verified after the fourth second. Performance between N.I., Stage 1, and Stage 2 P.D. subjects revealed significant differences (P < 0.01) among all three groups, regardless of FB condition. One of the revealing aspects of this investigation was the establishment of significant differences in visual motor performance of individuals in the early stages of the disease compared to previous reports of extremity deficits in the later stages. © 1991.