SINGLE UNIT NEURONAL STUDIES IN "PARKINSONISM"

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We propose to continue our tudy of the role of the basal ganglia in the initiation and control of behaviorally conditioned movements and compare it to the role played by the motor cortex and dentate nucleus of the cerebellum utilizing the technique of single unit recording and analysis of neuronal activity. We will then study changes in the neuronal activity of these areas following the production of parkinsonism in monkey by intravenous injection of 1-methyl-4phenyl-1,2,3-6-tetrahydropyridine. Previous studies in the basal ganglia have produced vague and often contradictory results probably due to the failure to control the type and complexity of the movement tasks. The basal ganglia may be concerned with only certain features of movement. Failure to isolate and test those features may account for this inconclusiveness of previous studies. Our study will attempt to identify those features of movement relevant to basal ganglia function as compared to the motor cortex and the dentate nucleus. Questions raised in the literature are whether the basal ganglia are functionally concerned with slow versus fast movements and visually-cued or guided versus self-paced movements. These issues will be tested by combining the behavioral training of quantifiable tasks, specifically designed to separate these issues, with EMG monitoring and techniques of single unit analysis of central neuronal activity. Using the same behavioral tasks, the functioning of the motor cortex and dentate nucleus will be examined to determine how they contrast with the basal ganglia. Comparison of these three regions of the motor system may provide useful insights regarding their functional interactions. Identification of those features of movement relevant to the basal ganglia may help to establish better experimental approaches to future studies of the functions and disorders of the basal ganglia. The study will also allow us to examine somatosensory input to the globus pallidus and putamen by training monkeys to tolerate sensory stimulation. Previous studies have produced conflicting results and have not attempted to correlate sensory reponses with activity changes during movement. This may give some insight to the processing of sensory information into a motor program by the basal ganglia.