Dopamine's activity appeared to increase two to three times over baseline levels in the brain area studied, the putamen, compared to a control area, the cerebellum. Improvements in scanning technology eventually may track cocaine's effects on the dopamine-generating nucleus accumbens, a smaller area nearby in the brain that is known to play a role in addictive behavior in animals, adds Godfrey Pearlson, M.D., professor of psychiatry and a lead author on the paper.
Brain cells use dopamine by binding the chemical to specific openings on their surfaces.
Pearlson used these openings to measure dopamine activity. First, he injected cocaine users with the compound raclopride, which binds to these same receptors. Soon after, scientists gave the subjects an injection of a placebo and scanned their brains. Then they scanned the patients again. But dopamine is still obviously a very important part of drug addiction.