Brain Imaging and Addiction

Dopamine is involved in drug reinforcement but its role in addiction is less clear. In recent years, however, we have witnessed a dramatic advance in our understanding of dopamine's role in drug abuse in the human brain driven by the growing application of brain imaging techniques, including positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Using PET to measure dopamine neurotransmission in the human brain, we have uncovered that dopamine striatal deficits are associated with disrupted prefrontal activity (most pronounced in cingulate gyrus and orbitofrontal cortex) that may explain the loss of control, the compulsive drug taking, and the reduced responsiveness to natural reinforcers typical of addiction. This insight has enabled novel therapeutic approaches for restoring the brain dopaminergic system, which could improve executive function, enhance inhibitory control, and interfere with compulsive responses, while improving the motivation to engage in nondrug-related behaviors.