- In 1912 Kinnier Wilson coined the term extrapryamidal system to describe a functional mammalian basal ganglia system that interacted with brainstem structures to influence motor behavior independently of the pyramidal tract. Wilson's emphasis on the role of the basal ganglia in motor behavior was driven in large part by the important early discoveries by Vogt (1911) and Wilson of motor disorders in humans following damage to this brain region. In addition to refining our understanding of basal ganglia function in motor behavior, almost a century of subsequent research on the behavioral functions of the mammalian basal ganglia has revealed a group of structures whose functions are diverse in nature. Basal ganglia research now encompasses several psychological domains, and evidence of a role for various components of this group of subcortical structures in behavior comes from studies in both humans and experimental animals. This brief survey of the basal ganglia begins with a consideration of basic basal ganglia anatomy and neurochemistry, and subsequently describes basal ganglia function in neurodegenerative disease, reward and drug addiction, learning and memory, and psychopathology.