When lab rats are jonesing for a fix, they’ll consume cocaine even when they know they’ll receive a painful electric shock to the foot. Similar to addicted humans, drug-dependent rats continue to use, regardless of the consequences.
Happily, scientists at the National Institute of Drug Abuse (NIDA) have found a way to reverse this cycle of addiction and self-harm. When researchers focused a laser light on the addicted rats’ prefrontal cortex—a brain region crucial for decision making and impulse control—their craving for cocaine vanished.
"When we turn on a laser light in the prelimbic region of the prefrontal cortex, the compulsive cocaine seeking is gone," said Antonello Bonci, MD, scientific director of the intramural research program at NIDA and an adjunct professor at the University of California San Francisco and Johns Hopkins University in a press release.
Bonci’s team, led by Billy Chen of NIDA, inserted light-sensitive proteins into the nerve cells, or neurons, in this part of the rats’ brains. When researchers shone a laser onto the light-sensitive cells, they were able to turn the corresponding neurons “on” and “off.”
The addicted rats showed very little neural activity in the prefrontal cortex before laser treatment, and research has shown that cocaine-addicted humans have similarly low activity in this area of the brain. However, when researchers turned the rats’ neurons “on,” the rats were able to regain their impulse control and kick their drug craving.
Chen’s study was published this week in the journal Nature.
What Does This Mean for Us Humans?
An estimated 1.4 million Americans were addicted to cocaine in 2009, and 1.5 percent of young adults ages 18 to 25 reported using the drug regularly. In 2008, one in four of the nearly two million emergency room visits for drug abuse was attributed to cocaine or crack use.
To halt this disturbing trend, researchers are developing safer, less invasive ways to turn cells in the human prefrontal cortex back “on.”
The most promising technique is called transcranial magnetic stimulation, or TMS, which involves placing a large electromagnetic coil against your scalp and generating a series of electrical pulses to get your neurons firing. A similar technique called transcranial direct current stimulation (tDCS) has been used successfully to treat severe depression.
Bonci’s team plans to begin human trials at the National Institutes of Health as soon and they’ve secured funding. They will try a few sessions a week of TMS therapy on cocaine addicts in an effort to rejuvenate the prefrontal cortex and help patients stop using cocaine for good.