The
caudate nucleus is one of three basic structures that make up the
basal ganglia, along with the
putamen and
globus pallidus. Also, in conjunction with the
thalamus and two related structures (the
substantia nigra and
subthalamic nucleus), the caudate nucleus constitutes a system that is responsible largely for voluntary movement. While this system has long been associated with motor processes due primarily to the basal ganglia’s role in
Parkinson's disease, there is mounting evidence that the structures that make up the basal ganglia—the caudate nucleus included—play important roles in various other nonmotor functions as well. Organizationally, the interplay between the basal ganglia and various regions in the brain is best described as a series of cortico-striatal loops, in which the
striatum receives axons from the
cortex (along with the
putamen, the caudate nuclei are the main input regions for the
basal ganglia), processes the information, then relays this back to distinct
cortical regions (hence the name
cortico-striatal). The caudate plays an important role in three of these loops: the oculomotor, dorsolateral, and ventral/orbital circuits. In a related way then, the caudate nucleus has been implicated with voluntary movement, learning, memory, sleep, and social behavior.