Normally, when dopamine binds to receptors on target cells it is taken up and removed from the synapse within a short period of time. However, brain imaging reveals that cocaine, a highly addictive drug, interferes with the removal of dopamine from the synapse. As a result, dopamine lingers there and continues to produce pleasurable feelings that persist beyond those produced by ordinary physiological stimuli. In this way cocaine hijacks the brain’s reward system.
