 The limbic basal ganglia circuits are influenced heavily by extracellular dopamine.Increased dopamine results in inhibition of the Ventral pallidum, entopeduncular nucleus, and substantia nigra pars reticulata, resulting in disinhibition of the thalamus.This model of direct D1, and indirect D2 pathways explain why selective agonists of each receptor are not rewarding, as activity at both pathways is required for disinhibition.