Study: Cognitive Deficits ... continued
The researchers found that those who misuse cocaine were significantly
less proficient than non-drug users at accurately completing the task.
The study showed that the demands of working memory required increased
activation of two brain regions, the anterior cingulate cortex (ACC) and
the prefrontal cortex. These areas have been consistently associated with
memory and higher brain function.
"Previous research that examined cognitive function in cocaine abusers
identified decreased activity in the ACC," said Garavan. "But our study is
the first to show that the difficulty cocaine users have with inhibiting
their actions, particularly when high levels of reasoning and
decision-making are required, relate directly to this reduced capacity for
controlling activity in the ACC and prefrontal regions of the brain."
The researchers concluded that cognitive deficits are part of the reason
why individuals who misuse cocaine persist in using the drug or return to
it after a period of abstinence.|||
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The Brain: The Origins of Dependence
By Sharon Begley
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.
"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...»»
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