Abstract
Motor impairment in Parkinson's disease, clinically defined as “bradycinesia or akinesia” has been considered as resulting only from motor system involvement. Combined analysis of the afferent sensory and efferent motor systems was studied in 20 patients with Parkinson's disease with a simple aiming task on a visuomotor performance system. Dynamic characteristics in patients with Parkinson's disease were assessed by two main parameters decreased amplitude of the voluntary movement (=low gain constant) and delayed initiation of the voluntary movement (=prolonged reaction time). The visual-event-related potentials (P300) elicited in a target detection paradigm was recorded in 12 patients. P300 latency was significantly prolonged in the patient group than in the normal subjects (p<0.02). P300 has been shown to be intimately related to the cognitive process in the human brain and might serve as a tool to monitor and evaluate the cognitive state in a clinical situation. The main cause of cognitive impairment in Parkinson's disease may include coexisting dementia and defective motivation. This type of cognitive dysfunction may also serve partly as a cause of motor performance involvement, bradycinesia.
