Integrative Networks Across Basal Ganglia Circuits

Publisher Summary This chapter reviews the basic circuitry that underlies parallel processing. It outlines the anatomical basis for integration across different cortico-basal ganglia circuits; and also discusses functional data that support integrative processing through the basal ganglia. The basal ganglia (BG) work in concert with the frontal cortex to orchestrate and execute motivated, planned behaviors requiring limbic, cognitive, and motor control systems. The basal ganglia are traditionally considered to process this information in parallel and segregated functional streams consisting of reward, associative, and motor control circuits. It reviews that frontal cortex contains divisions associated with specific functions; expressed behaviors are the result of a combination of complex information processing that involves all of frontal cortex. Indeed, appropriate responses to environmental stimuli require continual updating, and learning to adjust behaviors according to new data. This necessitates coordination between limbic, cognitive, and motor systems, to form smoothly executed, goal-directed behaviors. Parallel processing of functional information through different basal ganglia circuits does not address how information flows between circuits, thereby developing new, or adapting to previously, learned behaviors. While the anatomical pathways appear to be generally topographic from cortex through BG circuits, and there are some physiological correlates to the functional domains of the striatum, a large growing body of evidence supports a duel processing system. Thus, information is not only processed in parallel streams, but also through integrative mechanisms through which information can be transferred between functional circuits.