Basal ganglia: Their role in complex cognitive procedures in experimental models and in clinical practice.

Apart from the well known role of the basal ganglia (BG) in motor control, their important role in regulating the cognitive functions is emerging. This article traces the scientific work that explores this role of BG in reinforcement learning, perceptual decision making, and other nonmotor pathways (speech fluency, cognition, attention and behaviour). It also highlights the important role played by the BG networks in determining the development of a child's brain. It retraces the various pathways and connections of the BG with the cerebral cortex, cerebellum and other regions that may be utilized in the establishment of complex cognitive procedures. Various diseases that may be the direct result of disruption of these basal ganglionic networks and interconnections are also recounted.