image: B.Chen/NIDA
(Image: B.Chen/NIDA)

Imaging studies of cocaine addicts’ brains typically show low activity patterns in the region that is key to impulse control, the prefrontal cortex. The same goes for rodents that have been turned into cokeheads in the lab.
Whether the use of the drug itself further compromises impulse control, leading to compulsive use in spite of life-threatening effects, still isn’t clear.
But a team of neuroscientists reports in Nature this week that, at least in rats, there is a way to wipe away the addictive behavior with optogenetics.
By inserting light-sensitive proteins into neurons in a rat’s prefrontal cortex, and then directing laser light at them through fiber optic cables, the researchers were able switch on and off the animals’ cocaine-seeking behavior.
The University of California, San Francisco, where several of the scientists in the study work, reports that the lead author, Billy Chen of the National Institute on Drug Abuse, which funded the work, says such a therapy could be tested immediately in humans.
Instead of using invasive laser optics however, UCSF reports that clinical trials are being designed to test the use of “transcranial magnetic stimulation” outside the scalp, a technique that has been used to treat depression. The idea is that electric currents would modulate neurons the way the lasers did in mice.
The scientists write in Nature:

“Our results show a marked reduction in prelimbic cortex excitability in compulsive cocaine-seeking rats, and that in vivo optogenetic prelimbic cortex stimulation decreased compulsive drug-seeking behaviors. Thus, targeted stimulation of the prefrontal cortex could serve as a promising therapy for treating compulsive drug use.”


It will be interesting to see what other types of addictive behaviors might be switched off the same way, or if there are healthy addictions that might be switched on.