In a study on laboratory rats, scientists discovered that certain nerve cells in a specific region of the brain play a key role in drug addiction relapse.Individuals who recover from addiction often face environmental stimuli associated with drug use, such as hearing a particular song or walking through a certain neighborhood. These triggers could provoke a return to drug use.In studying how environmental stimuli cause relapses, researchers at Rutgers studied the nerve cells in the nucleus accumbens, a brain region found to be involved in the addictive effects of drugs.

“We’ve identified a part of the brain that appears to process these memories,” said Mark West, a professor of psychology at Rutgers. “This might be one of the brain areas that a very skilled pharmacological approach could target.”

For the study, rats were able to self-administer cocaine by pressing a lever. When the animals pressed the lever, a tone sounded, which they came to associate with the drug. At the end of three weeks, the cocaine and lever were removed. A month later, the researchers returned the lever. But the rats ignored it until the tone sounded again.The researchers found that the nerve cells in the accumbens responded instantaneously when the tone was sounded.

“When we started to play the tone that had been paired with cocaine, the animals began to press the lever at a fairly high rate,” said West. “It indicated that the animals had a persistent memory — they remembered the significance of the tone. We interpreted the resumption of lever pressing as a behavioral relapse.”

Researchers said the study’s findings could help in the development of new addiction therapies and intervention strategies.The study is published in the Aug. 13 issue of the Journal of Neuroscience.


Source:Ghitza, U., Fabbricatore, A., Prokopenko, V., Pawlak, A., & West, M.
(2003) Persistent Cue-Evoked Activity of Accumbens Neurons after
Prolonged Abstinence from Self-Administered Cocaine.
Journal of Neuroscience, 23(19): 7239-7245.