Prefrontal Cortex Stimulation Helps Cocaine-Addicted Rats

Dr. Billy Chen, Dr. Antonello Bonci, and their colleagues recently discovered that stimulating the prefrontal cortex (PFC) in cocaine-addicted rats has stopped compulsive drug-seeking. According to the National Institute on Drug Abuse (NIDA), the researchers found that “cocaine dampens neuronal excitability” in the PFC of rats, which suggests that cocaine use becomes more compulsive when the PFC is hyperactive past a certain point (2014).

Only one in five people who try cocaine will progress to compulsive use, which Dr. Chen and his colleagues have now discovered might be due to a greater impairment of PFC function. “The PFC is largely responsible for self-control,” NIDA stated, adding that brain-imaging studies have shown lower PFC activity in people with substance use disorders.

The study on rats was conducted after the rats self-administered cocaine for six months. To sort out compulsive drug-seekers from the group of rats in the trial, the researchers gave a mild electric shock to the foot of those attempting to receive the cocaine infusion. After four days, only 30 percent of the rats continued to seek cocaine, which demonstrated compulsive use. The researchers then examined both groups, as well as rats that had not been part of the study, and discovered the cocaine-seeking rats had significantly less excitable prelimbic neurons firing in their PFC.

After realizing that slowing down the prelimbic neurons in the 70 percent of noncompulsive drug-seeking rats turned them into compulsive drug-seekers, Dr. Chen and his colleagues thought that reversing the tests might have the opposite effect. As NIDA stated, “If decreasing neuron activity beyond a threshold triggers compulsive drug-seeking, then raising activity above that threshold might restore self-control” (2014). 

The results were positive; when the experiment was reversed the compulsive behavior dropped off and rats began to self-administer half the amount of the cocaine infusion they were consuming before. “I was very surprised that when we boosted the neuronal activity in prelimbic neurons,” stated Dr. Chen, “the rats’ behavior was very quickly altered” (NIDA, 2014). 

Based on the conclusions of these experiments, finding a way to fix decreased PFC function in humans might help people suffering from substance abuse and even other people suffering from unwanted and potentially damaging compulsive behaviors.  

References

National Institute on Drug Abuse. (2014). Prefrontal cortex stimulation stops compulsive drug seeking in rats. NIDA Notes. Retrieved from http://www.drugabuse.gov/news-events/nida-notes/2014/01/prefrontal-cortex-stimulation-stops-compulsive-drug-seeking-in-rats