Using a state-of-the art imaging technique, researchers at the Massachusetts General Hospital (MGH) have shown, in greater detail than before, how specific areas of the human brain react to cocaine, distinguishing patterns of activation associated with feelings of euphoria and craving among addicts. Their report, appearing in the September issue of Neuron, reveals that a much broader range of brain structures is involved in the cocaine "rush" than previously suspected and that the role of brain areas long thought to be involved in making cocaine rewarding and addictive is more complex than previously believed.

"This study gives us a detailed picture of cocaine's effects on brain circuits involved in both aspects of the reward system: reinforcement, which refers to an immediate positive or pleasurable reaction, and incentive, which in this context means motivation to repeat an activity,"says Hans Breiter, MD, a member of the MGH Radiology and Psychiatry Services and first author of the study. Much current understanding of how drugs like cocaine affect the brain has come from animal studies that correlated brain activity with observed behaviors, like pressing a lever to receive additional doses of drugs. But animals cannot report the kinds of subjective, emotional reactions humans experience and describe by terms such as "rush," "high," "low" and "craving." The current study supports previous animal observations of how the brain responds to cocaine and provides much greater detail regarding reactions of specific, tiny structures and how they relate to the feelings of the cocaine user.

"Understanding how different circuits are activated during the different stages of drug use and withdrawal can help us design and monitor novel treatments," says Steven E. Hyman, MD, director of the National Institute of Mental Health. Previously a member of the MGH Psychiatry Service, Hyman also is senior author of the Neuron paper.

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Contact: Sue McGreevey
mcgreeveys@a1.mgh.harvard.edu
(617) 724-2764
Massachusetts General Hospital
26-Sep-1997