Dopamine has a reputation as the key player in the brain's reward circuits, making us seek out pleasurable experiences, but growing evidence points to a multipronged role for the neurotransmitter. In particular, dopamine may also reinforce avoidance of painful experiences. Researchers have now mapped dopamine neurons in the brain with fiber photometry and discovered two parallel dopamine circuits driving attractive and aversive reinforcement learning and motivation.

Source: Dopamine's yin-yang personality: It's an upper and a downer