A TECHNIQUE FOR REMOVAL OF THE VISUOPERCEPTUAL COMPONENT FROM TRACKING PERFORMANCE AND ITS APPLICATION TO PARKINSONS-DISEASE

Although it is well established that subjects with Parkinson's disease perform poorly on complex sensory-motor tasks, the extent to which th is is due to visuoperceptual deficits is unclear. We measured the perf ormance of 16 patients with Parkinson's disease, both on and off drugs , and 16 age and sex matched control subjects on preview and nonprevie w tracking tasks and a nonmotor test of dynamic visuoperception. Order effects were controlled for by a randomized cross-over design. Perfor mance on the perceptual task was measured in terms of perceptual resol ution and was found impaired in the Parkinsonian group. The contributi on of visuoperceptual function to tracking performance was removed usi ng the concept of a visuoperceptual buffer-zone. The mean tracking err or remained impaired on all tracking tasks and demonstrated that limit ations in visuoperceptual function play only a minor role in the track ing errors in both Parkinsonian and control subjects. It is clear that the technique for determining the visuoperceptual component of perfor mance on complex sensory-motor tasks has considerable scope for applic ation in studies of a variety of brain disorders.