Fig. 2.

Neural mechanisms underlying pain modulatory circuits involving the rostral agranular IC (RAIC). Neurons in the RAIC receive dopaminergic fibers from the VTA/SN. In the RAIC, there are close appositions between dopaminergic fibers and GABAergic interneurons. Then, GABAa neurons project to the locus coeruleus (LC), while GABAb neurons project to the amygdala (AMY). Altogether, by the activation of D1 and D2 receptors, dopaminergic modulation of the RAIC occurs through different types of GABAergic interneurons. The circuit provides potential access for reward-motivation information to pain modulation system. PAG periaqueductal gray, RVM rostroventral medulla, SN salience network, VTA ventral tegmental area.