 Progress in understanding the functions of the basal ganglia has been slow.The most popular hypotheses, broadly stated, propose that the basal ganglia play a central role in action selection.The action selection theory in its simplest form proposes that when a person or animal is in a situation where several behaviors are possible, activity in the basal ganglia determines which of them is executed, by releasing that response from inhibition while continuing to inhibit other motor systems that if activated would generate competing behaviors.