ABSTRACT
A theory of the basal ganglia is developed in Part I. A central feature of this theory is the defi nition of executive functions (involving decision-making about behavior, attentional focus, and underlying motivational target), and the separation of these functions from both the associative functions of the cerebral cortex and the mechanisms of brain stem, cerebellum, and spinal cord involved in motor coordination. An essential aspect of the theory is thus that the basal ganglia are concerned not with motor control or coordination (as has often been implied in the past), but with these executive functions such as selection of behavioral strategies, foci for attention, and long-term goals. These two functional processes-behavioral selection and motor coordination-generally function together in producing motor/behavioral output, yet, for theoretical reasons, it is suggested that they involve quite separate styles of information processing and neural machinery.
