Most models of basal ganglia function rely on the concept of parallel processing. This is based on the idea that each cortical area mediates a parallel and segregated circuit through each of the basal ganglia structures. Therefore, these models do not address how information flows between circuits, thereby developing new learned behaviors (or actions) from a combination of inputs from emotional, cognitive, and motor cortical areas. Although the frontal cortex is indeed divided according to specific functions, expressed behaviors are the result of a combination of complex information processing that involves all the frontal cortex. The development and execution of appropriate responses to environmental stimuli require continual updating, and learning and adjustments of the response. Thus, response learning does not represent a separate motor, cognitive, and motivational tract; rather, it is the combination of these areas working together that forms a smoothly executed, goal-directed behavior. Although the anatomical pathways appear to be generally topographic from cortex through basal ganglia circuits and there are some physiological correlates to the functional domains of the striatum, there are major points that argue against
