ZAPPING parts of the brain with electrical current has been found to boost memory and may relieve depression. Now psychologists are planning a new test of its powers. This month, transcranial direct current stimulation (TDCS) will be tested in a prison in Spain, as part of controversial efforts to see if it can calm violent urges.
鈥淭he study is to try to find out if TDCS has an effect on different assessments of aggression,鈥� says Andr茅s Molero-Chamizo at the University of Huelva, who is leading the project. 鈥淚t could help to keep order inside a prison.鈥�
The experiment will take place in Huelva prison, which has seen a series of violent incidents in recent years, including an attack on the governor in 2017. But Molero-Chamizo says the TDCS work isn鈥檛 a response to that, and if the technique works, it could have applications outside prisons too, as a 鈥渟imple, cheap, non-pharmacological way to control aggressiveness鈥�.
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The study will involve a psychologist strapping two electrodes to the foreheads of prisoners, including at least a dozen men serving a murder sentence. For each person, the current will be turned on for 15 minutes, on three successive days. Before getting started, the participants will be asked if they agree with statements including 鈥渙nce in a while, I can鈥檛 control the urge to strike another person鈥� and 鈥淚 sometimes feel like a powder keg ready to explode鈥�. They will then answer the same questions after the last stimulation session.
Molero-Chamizo says it was much easier to get permission to work with the prisoners than with medical patients and students. The prisoners have all volunteered for the study, which has been approved by the Spanish government, prison officials and a university ethics committee.
This isn鈥檛 the first time Molero-Chamizo has worked with violent prisoners. His team recently published results from an experiment in which it tried a different form of electrical brain stimulation to influence the aggressive thoughts and attitudes of 41 male convicts, including 15 serving sentences for murder.
The team found that stimulating the prefrontal cortex 鈥� a region of the brain involved in moderating social behaviour 鈥� for 15 minutes a day for three consecutive days led to a decline in self-described levels of aggression (Neuroscience, ). Prisoners who wore electrodes but had no current applied showed no difference.
Aggressive intent
The latest experiment aims to check those findings and analyse some other physiological clues about mental state. The full details haven鈥檛 yet been finalised 鈥� they depend on the discretion of the prison governor 鈥� but the team hopes to take saliva samples, and analyse them for the stress hormone cortisol as a separate measure of aggressive intent.
Some theories of aggression have linked violent outbursts to a lack of activity in the prefrontal cortex region of the brain, which is also involved in complex decision-making and personality.
Studies have suggested that TDCS may be useful for a range of conditions, including schizophrenia and autism, but replicating many results has been difficult. Some studies have indicated that TDCS can influence aggression, but others have shown that the effect isn鈥檛 real.
鈥淓lectrical brain stimulation might be helpful for serious offenders, and I think we should find out鈥�
Adrian Raine, a neurocriminologist at the University of Pennsylvania, has studied TDCS and aggression and supports the Spanish project. 鈥淚t might be helpful for serious offenders, and I think we should find out,鈥� he says.
One scientist did raise concern about the ethics of the trial. Speaking to New Scientist, Delaney Smith, a forensic psychiatrist in Columbus, Ohio, said: 鈥淚 would have big concerns about this. Prison is an inherently coercive environment. Prisoners could always be thinking that this might be beneficial to their case in the future.鈥� This means it is hard to know if anyone signing up is truly doing it voluntarily.
Researchers around the world have long been fascinated by the potential of modifying brain activity, including in Spain. In the 1960s, neuroscientist Jos茅 Rodr铆guez Delgado used a remote-controlled brain implant to stop an angry bull that was charging him in a bullring in Cordoba.
