The researchers compared nerve-cell firing action in both groups of rats by examining cells from a brain area known as the prefrontal cortex. This area is involved in higher brain activity. This includes the making of decisions, controlling unplanned behavior and unwillingness to change one’s mind.

Scientists discovered that the addicted rats had reduced activity in a part of the brain cortex called the prelimbic region. The area showed weakness in the self-control processes needed to resist the drug. So, the scientists developed a plan to increase the animal’s ability to control itself.

The first step was to inject the brain area with a harmless virus carrying a protein that responds to light. After several weeks, the scientists placed a very small fiber optic device into the prefrontal cortex, and sent light to wake up the sleepy area.

Antonello Bonci praised the results.

“When we turned on some activity in this prefrontal cortex, we could see that the compulsive cocaine seeking was gone.”

He says researchers then turned the process around. The rats that had changed their behavior because of the shocks again became cocaine seekers. This happened because the researchers used the fiberoptic method to reduce neuronal firing in the prefrontal cortex.

Dr. Bonci says investigators are now designing human clinical tests for electromagnetic brain stimulation that is non-invasive. He says they are doing this to increase the hypoactive, or inactive, prefrontal cortex of volunteer drug users.