Cell type- and projection-specific contributions to social hierarchy in the ventral tegmental area

초록

Social animals compete for limited resources, resulting in the formation of social hierarchy to maintain stable social groups. It is hypothesized that a key driving force behind social hierarchy is the motivation and reward system regulated by the mesocorticolimbic dopaminergic pathway. However, the specific contributions of this circuitry to social hierarchy remain largely unknown. In this study, we investigated cell type- and projection-specific contributions to social hierarchy in the ventral tegmental area (VTA), a main component of mesocorticolimbic dopaminergic pathway. We found that the intrinsic firing rate of dopaminergic neurons in the VTA (VTADA) is higher in social dominants (DOM), whereas the intrinsic firing rate of GABAergic neurons in the VTA (VTAGABA) is higher in social subordinates (SUB). Additionally, inhibition of VTADA or VTAGABA activity decreased or increased social hierarchy, respectively. Furthermore, we observed that inhibition of VTADA projecting to the nucleus accumbens (VTADA-NAc) or the mPFC (VTADA-mPFC) decreased or increased social hierarchy, respectively. These results suggest that social hierarchy is oppositely controlled by distinct cell types in the VTA and by specific VTADA projections.