How does dopamine drive motivation and reward?

The answer

Dopamine, often mischaracterized as the 'pleasure molecule,' is more accurately the brain's motivation and prediction signal. Dopamine neurons in the ventral tegmental area fire not primarily during the experience of reward, but in anticipation of it and especially in response to unexpected rewards. When a reward is better than expected, dopamine neurons fire more; when it is worse, they fire less. This reward prediction error signal is what drives learning and motivation, teaching the brain which actions lead to positive outcomes. The wanting (dopamine-driven motivation) and liking (opioid-driven pleasure) systems are neurologically distinct, which explains addictive behaviors where a person desperately wants something they no longer enjoy. Dopamine also plays critical roles in movement, attention, and working memory, and its dysfunction is central to Parkinson's disease, ADHD, and schizophrenia.