The striatum, or corpus striatum (also called the striate nucleus), is a nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives glutamatergic and dopaminergic inputs from different sources; and serves as the primary input to the rest of the basal ganglia. Functionally, the striatum coordinates multiple aspects of cognition, including both motor and action planning, decision-making, motivation, reinforcement, and reward perception. The striatum is made up of the caudate nucleus and the lentiform nucleus. The lentiform nucleus is made up of the larger putamen, and the smaller globus pallidus. Strictly speaking the globus pallidus is part of the striatum. It is common practice, however, to implicitly exclude the globus pallidus when referring to striatal structures. In primates, the striatum is divided into a ventral striatum, and a dorsal striatum, subdivisions that are based upon function and connections. The ventral striatum consists of the nucleus accumbens and the olfactory tubercle. The dorsal striatum consists of the caudate nucleus and the putamen. A white matter, nerve tract (the internal capsule) in the dorsal striatum separates the caudate nucleus and the putamen. Anatomically, the term striatum describes its striped (striated) appearance of grey-and-white matter. Structure The striatum is the largest structure of the basal ganglia. The striatum is divided into a ventral and a dorsal subdivision, based upon function and connections. The ventral striatum is composed of the nucleus accumbens and the olfactory tubercle. The nucleus accumbens is made up of the nucleus accumbens core and the nucleus accumbens shell, which differ by neural populations. The olfactory tubercle receives input from the olfactory bulb but has not been shown to play a role in processing smell. In non-primate species, the islands of Calleja are included. The ventral striatum is associated with the limbic system and has been implicated as a vital part of the circuitry for decision making and reward-related behavior. The dorsal striatum is composed of the caudate nucleus and the putamen. Staining can differentiate the striatum into two distinct compartments of striosomes or patches, and a surrounding matrix; this is particularly evident on the components of acetylcholinesterase and calbindin. More studies have been carried out on the dorsal striatum but the compartments have also been identified in the ventral striatum. In the dorsal striatum striosomes make up 10-15 per cent of the striatal volume.