Figure 2.

Afferent regulation of the dopamine system. (a) In a normal situation, a balance between the ilPFC → BLA → VP and the vSub → NAc → VP circuit leads to about half of the DA neurons firing spontaneously. (b) Hyperactivity of the ilPFC in major depressive disorders (MDD) leads to activation of the BLA, enhancing the inhibitory influence of the VP on the ventral tegmental area, causing an imbalance between the two circuits, with the result being a large, unopposed decrease of DA population activity, which is proposed to underlie anhedonia.