Projections of D2 Neurons in Different Subregions of Nucleus Accumbens Shell to Ventral Pallidum Drive Different Valence and Change in Speed

Nucleus accumbens (NAc) plays an important role in emotion and motivation. NAc D1 neurons are widely accepted to be associated with reward, while the role of D2 neurons are more evasive. D2 neurons are traditionally associated with aversion. However, some reports have attributed positive motivational roles to them. Here, we combined optogenetics and rabies-mediated transsynaptic tracing to demonstrate the anatomical and functional heterogeneity of NAc shell (NAcSh) D2 neurons. D2 neurons in the dorsomedial zone drive positive preference and increase reward motivation while D2 neurons in the ventral zones drive aversion and decrease reward motivation. Furthermore, D2 neurons in ventromedial NAcSh increase movement speed and those in the ventrolateral NAcSh decrease movement speed. D2 neurons in different subregions of NAcSh target downstream cell types differentially. Therefore, the finding of the heterogeneity in the anatomy and function of NAcSh D2 neurons clears up some of the controversy in the literature.