Basal Ganglia: Mechanisms for Action Selection

The basal ganglia are an interconnected circuit of foreand midbrain nuclei common to all extant vertebrates, including the lamprey, which diverged from the main vertebrate line approximately 560MYA.Moreover, there are analogous structures in birds and bony fish. The preservation of this circuit implies a crucial operation that solves a problem common to all vertebrates. While many functions for the basal ganglia have been proposed, our current best theory to unify these ideas is that this circuit solves the common problem of action selection. Informally put, this is the problem of how to decide what to do next.