Long after an addict has become drug-free, simple events or circumstances that were associated with prior drug use, such as walking through a particular neighborhood or hearing a particular song, can reawaken memories that trigger a craving and provoke a relapse. These environmental stimuli may render an addict vulnerable to a return to compulsive drug use.
"We've identified a part of the brain that appears to process these memories," said Rutgers psychology professor Mark West. "This might be one of the brain areas that a very skilled pharmacological approach could target."
West and his Rutgers colleagues published their findings in the Aug. 13 issue of the Journal of Neuroscience. They concentrated their work on nerve cells or neurons in the nucleus accumbens, a brain region known to be involved in the addictive effects of drugs.
They were searching for those nerve cells that respond to a drug-associated environmental stimulus. The laboratory work employed a design, previously demonstrated to be a good model of human addiction, in which rats were able to self-administer a specific drug. The animals were provided cocaine, one of the most highly addictive narcotics, dispensed to them when they pressed a lever. Microelectrodes that recorded the activity of single neurons were used to monitor nerve cells in a part of the nucleus accumbens known as the shell.
As the animals self-administered the cocaine, a tone was sounded and they came to associate the tone with the drug. If an animal pressed the lever in the absence of the tone, no cocaine was dispensed. At the end of three weeks, the rats had lear
Contact: Joseph Blumberg
Rutgers, the State University of New Jersey