Dopamine spikes from unpredictable events. “Games of chance” are
just such events, so it isn’t surprising that gambling boosts
dopamine the same way drugs do.1 Dr. David Zald, at Vanderbilt
University, scanned subjects’ brains while playing a computer
game simulating gambling. In some cases, subjects were
guaranteed to win with every fourth play; for others, winning
was unpredictable. Dr. Zald found large increases in dopamine
activity only when winning was unexpected.2 The inherent
unpredictability involved in gambling sets the stage for the
brain to experience repeated dopamine highs, which can be
addictive.3 fMRIs of compulsive slot-machine players showed they
had less blood flow to their Limbic “Reward” systems compared to
a control group, indicating they had more sluggish reward
networks. They compensate by boosting dopamine through
gambling.4 Similarly, in gambling addicts the striatum, a key
part of the Reward System, was less active on winning than in a
control group, as if the addicts experienced win