A laser beam that targets the prefrontal cortex of the brain has been shown to turn off cocaine addiction in rats.

By stimulating one area of the brain, scientists at the National Institutes of Health and the Ernest Gallo Clinic and Research Center at UC San Francisco were able to turn cocaine-addicted rats clean and make non-addicted rats look for the drug.

The research, which will be published in Nature, shows the role that the prefrontal cortex plays in cocaine addiction. The scientists believe the therapy could be tested on humans immediately.

Antonello Bonci, of the NIH's National Institute of Drug Abuse, said: "When we turn on a laser light in the prelimbic region of the prefrontal cortex, the compulsive cocaine seeking is gone."

In 2010, an EU report found that the UK was at the top of the league table of cocaine use in Europe. The British Crime Survey in the same year found that 6.6 percent of 16-24-year-olds use cocaine.

Treatment for depression

Rats have extremely low levels of activity in the prefrontal cortex - important in impulse control and decision making. Studies have shown that human coke addicts have similarly low levels of activity in this region.

Researchers took light-sensitive proteins and inserted them into neurons in the rat's prefrontal cortex. They then activated the region with a laser to turn the cells "on and off".

Turning on the cells increased activity in the region and wiped out the compulsive behaviour; turning them off resulted in non-addicted rats seeking out cocaine.

Bonci said that there was a way to induce a similar result in humans through magnetic simulation, which applies an external electromagnetic field to the brain - a technique sometimes used as a treatment for depression.

Researchers plan to start trials at the NIH to stimulate the prefrontal cortex of human cocaine addicts.