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Fighting ADDICTION
SCIENCE: New research on how cocaine, heroin, alcohol and amphetamines target neuronal circuits is revealing the biological basis of addiction, tolerance, withdrawal and relapse.
One by one, each crack addict took his turn in the fMRI tube, its magnets pounding away with a throbbing bass. A mirror inside was angled just so, allowing the addict to see a screen just outside the tube. Then the 10-minute video rolled. For two minutes, images of monarch butterflies flitted by; the fMRI, which detects active regions in the brain, saw nothing untoward. Then the scene shifted. Men ritualistically cooked crack... an addict handed cash to a pusher ... users smoked. It was as if a neurological switch had been thrown: seeing the drug scenes not only unleashed in the addicts a surge of craving for crack, but also triggered visible changes in their brains as their anterior cingulate and part of the prefrontal cortex-regions involved in mood and learning-lit up like Times Square. Nonaddicts show no such response. The fMRI had pinpointed physical changes in the brain that apparently underlie cue-induced craving, showing why walking past a bar, passing a corner crack house or even partying with the people you used to shoot up with can send a recovering addict racing for a hit. "The brain regions that became active are where memories are stored," says Dr. Scott Lukas of McLean Hospital in Massachusetts, who led the 1998 study. "These cues turn on crack-related memories, and addicts respond like Pavlov's dogs."
"This is your brain on drugs": it's not just an advertising line. Through fMRI as well as PET scans, neuroscientists are pinpointing what happens in the brain during highs and lows, why withdrawal can be unbearable and-in one of the most sobering findings-how changes caused by addictive drugs persist long after you stop using. "Imaging and other techniques are driving home what we learned from decades of animal experiments," says Dr. Alan Leshner, director of the National Institute on Drug Abuse. "Drugs of abuse change the brain, hijack its motivational systems and even change how its genes function."
An addicted brain is different-physically different, chemically different-from a normal brain. A cascade of neurobiological changes accompanies the transition from voluntary to compulsive drug use,...