At NIDA's Bayview campus, many fMRI studies are aimed at developing therapies to help smokers and drug addicts kick their habits, Stein said. Researchers are also trying to understand why addicts are so prone to relapse.
"Drugs, we believe, fundamentally change your brain - that's why people who quit smoking have a phase of irritability during withdrawal," Stein said. "The question becomes, are these changes reversible?"
In a recent study, Stein and Hahn placed 16 smokers and 16 nonsmokers in a simulated fMRI scanner and activated machinery so the volunteers thought their brains were being scanned.
Then the subjects performed a series of progressively harder memory tasks - requiring them to recall images they had just seen. Periodically, researchers also showed the volunteers pictures of cigarettes between the images.
The researchers found that the smokers performed better than nonsmokers on difficult memory tasks when shown a cigarette as a cue, most likely because it acted as an alerting mechanism for them - waking up their brains. The results show how the brains of smokers respond to conscious cues, the researchers say.
"It's a reaction to a smoking cue that happens without much thinking," Hahn said.
In follow-up tests, the researchers hope to unravel how brains respond to unconscious cues. As a first step toward that goal, they plan to test the same group of smoking volunteers while they undergo brain scans.
To download a new government pamphlet called "The Science of Addiction," go to baltimoresun. com/addiction. To view or print it, you will need Adobe Acrobat Reader, available at adobe.com.