Functional organization of basal ganglia output

The basal ganglia are thought of as a “brake” on motor pattern generators in the cortex, via thalamus and brainstem. When a movement is initiated by a specific motor pattern generator, basal ganglia output neurons projecting to competing generators increase their firing rate, thereby increasing inhibition. Other basal ganglia output neurons, projecting to the generators involved in the desired movement, decrease their discharge. This removes tonic inhibition and releases the brake from those desired generators, allowing selection of desired movements while inhibiting competing movements that may interfere with the posture or movement selected. (Mink JW. The basal ganglia and involuntary movements. Arch Neurol 2003;60:1365-68.)