New findings by a multicenter team of scientists suggest that cocaine's ability to activate particular regions of the brain may be at the heart of the intense desire to take the drug. The research, supported in part by the National Institute on Drug Abuse (NIDA), National Institutes of Health, implicates two adjacent regions in the right side of the brain's prefrontal cortex, known as Brodmann's areas BA 25 and BA 11, that are involved with emotional behavior, motivation, and salience (significance or relevance to oneself).

The study, led by NIDA Director Dr. Nora D. Volkow, is published in the April 13, 2005 issue of the Journal of Neuroscience.

The scientists examined images of biochemical activity in the brains of 21 adult male "sober" cocaine addicts and 15 healthy adult males. The scientists used a compound that is pharmacologically similar to cocaine and acts in the same way, on the same brain regions.

Results showed that two doses of the drug increased metabolism in BA 25 and BA 11 in the addicted men but decreased it in the controls. BA 25 is involved in emotional reactivity while BA 11 is involved in salience attribution and motivation. The responses seen in this study in both groups of participants suggest these regions play pivotal and complementary roles in cocaine addiction, with BA 25 processing the emotional response to the drug and BA 11 dictating the motivation to obtain and use it.

This research was also supported in part by the Department of Energy (Office of Biological and Environmental Research).