The research proposed will extend our initial work by studying the adequacy of motor preparation as well as by examining the processes that contribute to bradykinesia in Parkinson's disease patients. This research will allow precise description and identification of motor impairment by employing converging levels of analysis: reaction time, movement time, electromyographic and kinematics. Section I considers whether Parkinsonians adequately prepare movement by asking: whether Parkinsonians can control the amount of time they spend preparing movements, whether vision is used appropriately for movement amplitude preparation, and whether normal preparatory adjustments are made in the gain of long-latency reflexes (M1, M2, M3). Section II evaluates whether the context in which a movement is performed affects the organization and control of multi-joint hand movement. Section III addresses several related issues. Do Parkinsonians coordinate movement parts in a sequence, do they take longer to prepare responses within a sequence to identical responses prepared and executed on their own, and are responses in sequence timed as accurately as identical responses prepared and executed on their own? Upon completion of these series of experiments we should be able to determine whether akinesia and bradykinesia are primarily associated with inadequacies in preparatory processes, basic execution processes, and/or a combination of both. We are optimistic that both the basic scientist and the clinician will be well served by our data: the former by having information on the locus of the motor impairments and the latter by being presented with interpretations from which more objective assessment and rehabilitation procedures can evolve.
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