The nucleus accumbens

The striatum refers usually to the caudatus and putamen nuclei. These two nuclei are fused in the rat but separated in human. Some authors, however, consider the nucleus accumbens part of the striatum. And this can be very confusing. The nucleus accumbens (formally called nucleus accumbens septi, "nucleus leaning against the septum") is located underneath the caudate and putamen, and it is involved in motivational behaviour. This is why sometimes it is called the limbic striatum.

The distinction between striatum (i.e. caudate und putamen) and nucleus accumbens (also called ventral striatum) is important because these two areas are anatomically and functionally different. For example, the striatum receives dopaminergic inputs from the substantia nigra pars compacta; the nucleus accumbens from the ventral tegmental area.