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Atsushi Nambu "Dynamic model of the basal ganglia functions and movement disorders"

Abstract :

An important issue in the neuronal control of movements is how motor-related cortical areas modulate the activity of the output nuclei of the basal ganglia. Here I would like to introduce a dynamic model of the basal ganglia functions for the control of voluntary movements. When a voluntary movement is about to be initiated by cortical mechanisms, a corollary signal conveyed through the cortico-subthalamo (STN)-internal pallidal (GPi) hyperdirect' pathway first inhibits large areas of the thalamus and cerebral cortex that are related to both the selected motor program and other competing programs. Next, another corollary signal through the cortico-striato-GPi ?direct? pathway disinhibits their targets and releases only the selected motor program. Finally, the third corollary signal through the cortico-striato-external pallido (GPe)-STN-GPi 'indirect' pathway inhibits their targets extensively.
This dynamic information processing ensures that only the selected motor program is initiated, executed and terminated at the appropriate timing, whereas other competing programs are canceled. Based on this dynamic model of the basal ganglia functions, the pathophysiology of movement disorders, such as Parkinson's disease and dystonia, and the mechanism for the effectiveness of the stereotaxic surgery can better be explained by an increase or decrease of disinhibition and inhibition in the thalamus and cortex in the temporal and spatial domains.

Thomas Boraud