Striatums

The striatum, sometimes referred to in the plural as striata or striatums, is the largest subcortical component of the basal ganglia. In primates it comprises the caudate nucleus and putamen; in humans these nuclei form dorsal striatum, while a ventral part includes the nucleus accumbens and related limbic structures. The dorsal striatum is primarily involved in motor and habit learning, whereas the ventral striatum plays a key role in reward and motivation.

The striatum receives dense glutamatergic input from nearly the entire cerebral cortex and thalamus, and dopaminergic input from the substantia nigra pars compacta and ventral tegmental area. The principal neurons are GABAergic medium spiny neurons, which project to the output nuclei of the basal ganglia; local interneurons, including cholinergic cells, modulate their activity.

Functional organization maps sensorimotor, associative, and limbic circuits onto dorsal and ventral striatal regions. Through direct (D1 receptor) and indirect (D2 receptor) pathways, the striatum helps translate cortical intentions into movement plans and action selection, while contributing to reinforcement learning and habit formation via dopaminergic signaling.

Clinical relevance: degeneration of nigrostriatal dopamine in the dorsal striatum underlies motor symptoms of Parkinson disease; loss of striatal MSNs is central to Huntington disease; disruptions in ventral striatal circuits are linked to addiction, obsessive-compulsive behaviors, and psychiatric conditions. Lesions or stroke can produce changes in movement, motivation, or reward processing.