What is dopamine?

Dopamine is a neurotransmitter made mainly in two small brain areas, the substantia nigra and the ventral tegmental area. Swedish scientist Arvid Carlsson showed in the late 1950s that it acts as a messenger in its own right, work that earned him a share of the 2000 Nobel Prize. Studies by Wolfram Schultz in the 1990s found that dopamine neurons fire most strongly when a reward is better than expected, making dopamine a teacher that helps us learn what is worth pursuing. It is also vital for smooth movement: Parkinson disease symptoms appear after a large share of dopamine-producing cells have been lost. Apps, games and social media are often said to exploit this reward system with unpredictable likes and notifications.