The basal ganglia: from motor commands to the control of vigor

•Vertebrates are remarkable for their ability to select and execute motor skill.•Motor skill is defined by flexibility of execution while obtaining reliable outcomes.•Basal ganglia both command movement and control movement vigor in rodents.•Basal ganglia mediate implicit motivation in primates.

Vertebrates are remarkable for their ability to select and execute goal-directed actions: motor skills critical for thriving in complex, competitive environments. A key aspect of a motor skill is the ability to execute its component movements over a range of speeds, amplitudes and frequencies (vigor). Recent work has indicated that a subcortical circuit, the basal ganglia, is a critical determinant of movement vigor in rodents and primates. We propose that the basal ganglia evolved from a circuit that in lower vertebrates and some mammals is sufficient to directly command simple or stereotyped movements to one that indirectly controls the vigor of goal-directed movements. The implications of a dual role of the basal ganglia in the control of vigor and response to reward are also discussed.