Tracking tasks and the study of predictive motor planning in Parkinson´s disease

The authors have studied the performances of 16 subjects with PD (Parkinson´s disease) and 16 matched control subjects on a range of computerized tracking tasks (preview and nonpreview forms of sine, random, and step inputs, plus a random-step combination) and related tests. Predictive motor planning was studied by way of three types of advance information which may be available on a target´s path: memory (periodicity), form (speed/acceleration characteristics), and preview. PD subjects were impaired with respect to preview only. This deficit could, however, be a consequence of impaired visuospatial perception rather than being a true motor planning deficit. Hence, no evidence was found for impaired sensory-motor performance that could be unequivocally attributed to a deficit in predictive motor planning