CHAT and major depressive disorder: Therefore, in the VP, ChAT neurons regulate pain-, anxiety-, and depression-like behaviours through local ChAT circuits and the VP-BLA projection, whereas glutamatergic, GABAergic, and parvalbumin-positive neurons regulate aversion, reinforcement learning, arousal, and emotion, mainly via their projections to the lateral habenula, ventral tegmental area, and lateral hypothalamus34–37,63.