It’s early in the work, but scientists at the University of Pennsylvania and Nanyang Tech University believe that they figured it out with a small experiment that involved stimulating the prefrontal cortex, the part of the brain that is involved in complex thought and decision-making. The results were published in this week’s JNeurosci journal.
Research has shown that some people who have been violent have deficits in the prefrontal cortex. So researchers designed an experiment on what would happen if that part of the brain was stimulated.
The scientists recruited 81 “healthy” adults in Philadelphia. Half the group underwent a minimally invasive technique called transcranial direct-current stimulation, which sent a painless electrical current into the prefrontal cortex for 20 minutes. The placebo group, those who didn’t get the physical stimulation, got a low current for 30 seconds. Neither group knew who was getting the actual stimulation.
Then, the groups were given two hypothetical scenarios.
One story involved a physical assault. A man goes on a dinner date with a woman he has been seeing for two years. When he heads to the bathroom, a friend of his sits at the table and chats up the girlfriend. When the boyfriend gets back, he interrupts his friend asking for her number. Words are exchanged, and the boyfriend ends up hitting the other man over the head with a beer bottle.
The second scenario involves a couple on a first date. They’re watching a movie at the woman’s apartment. They start kissing during the movie, but as things become more intimate, the woman tells the man to stop. Despite her repeated protests, the man sexually assaults her.
The study participants were then asked to rate on a scale from 0 to 10 (with 0 being no chance and 10 being 100% chance) whether they would act like the violent protagonist. For those who had the brain stimulation, the likelihood that they would engage in a physical or sexual assault in these circumstances was 47% and 70%, respectively, lower than those who did not have the stimulation.
The authors think the results of this experiment hold promise.
“Much of the focus in understanding causes of crime has been on social causation. That’s important, but research from brain imaging and genetics has also shown that half of the variance in violence can be chalked up to biological factors,” study co-author Adrian Raine, a psychologist and a Penn Integrates Knowledge professor, said in a statement from Penn Medicine. “We’re trying to find benign biological interventions that society will accept, and transcranial direct-current stimulation is minimal risk. This isn’t a frontal lobotomy. In fact, we’re saying the opposite, that the front part of the brain needs to be better connected to the rest of the brain.”
This experiment does not mean that if scientists were to use this technique, all violence would go away any time soon. A lot more research is necessary, and the experiment involved only “healthy” people. Whether this could work onthose who are prone to violence or demonstrated violent tendencies in the past “remains to be seen,” according to the study.
It’s also unclear whether people’s intentions would stay the same over time, but the experiment suggests that this physical stimulation in the brain may have a positive impact on one’s thoughts.
“The challenge is, very angry, aggressive people often feel like they have the right to be violent,” said Dr. Prudence Gourguechon, a psychiatrist and psychoanalyst with a clinical practice in Chicago. She is not affiliated with the study but has worked with patients who struggle with violence.
In order to use this technique, you’d have to get a person’s consent, Gourguechon said. “And you may have another motivational issue here, because you’d have to find people who admit that they have a problem with violence first.”
She said the experiment is interesting, but it would need to be tested in people who are repeatedly violent or prone to violent acting out, rather than healthy subjects, to see whether it changes their violent intentions.
“The larger point of this study may be how it shows the real possibilities of more direct brain interventions,” said Dr. Jesse Viner, CEO and chief medical officer of Yellowbrick, a psychology practice in Evanston, Illinois, that uses a combination of techniques including technologies that target the brain, known as neuromodulation interventions. Its patient population includes youths who struggle with substance use disorders, trauma and other mental health issues. “The science is evolving away from treatments like medication that impacts every part of the body, into treatments that are more direct and focused brain interventions like this that are showing much more promise.”
The experiment showed that while there was a difference in the intent people had in the experiment of committing violence, there was no real difference in the way the two groups acted. Both groups were allowed to “release their negative energy” on a simulated voodoo doll meant to represent the friend or the date in the scenario. When it came to pushing pins into the doll, there was no difference between the groups’ behavior.
“This is not the magic bullet that’s going to wipe away aggression and crime,” Raine said. But he thinks it may be a kind of intervention that first-time offenders might want to try to reduce the chances they would commit violence again.
“The ability to manipulate such complex and fundamental aspects of cognition and behavior from outside the body has tremendous social, ethical and possibly someday legal implications,” Hamilton, an associate professor of neurology atPenn’s Perelman School of Medicine, said in the statement. “Perhaps, the secret to holding less violence in your heart is to have a properly stimulated mind.”