Brain-Boosting

Brain-Boosting Technique Might Help Some Functions While Hurting Others

Electrically stimulating the brain may enhance memory, but impede with a person’s ability to react without thinking.

New research suggests that one promising experimental method could come with a cost. Using a noninvasive technique to stimulate the brain, researchers found they could enhance learning when they targeted a certain spot. But that also made people worse at automaticity, or the ability to perform a task without really thinking about it. Stimulating another part of the brain had the reverse effect, on both learning and automaticity.

“This tells us something about the human brain,” says lead researcher Roi Cohen Kadosh, a neuroscientist at the University of Oxford, in England. “We can’t ask for everything without paying a price.” The findings were published Tuesday in the Journal of Neuroscience.

Cohen Kadosh and collaborators used a technique called transcranial electrical stimulation (TES), a noninvasive method for stimulating specific parts of the brain. The approach has previously been shown to enhance various brain functions, including working memory and attention, and is being used to help stroke patients regain lost language and motor skills (see “Repairing the Stroke-Damaged Brain”). But until now, little research had been done on whether improving performance on one task would come at the detriment of others.

The researchers compared performance among three groups—those who had stimulation to the prefrontal cortex, which is linked to complex planning and decision making, stimulation to the parietal cortex, part of the brain that helps integrate different types of information, and sham stimulation, in which participants thought they were getting the treatment but were not. The parietal stimulation group learned the best but had the worst automaticity, whereas the prefrontal cortex group had the opposite pattern. (It may seem counterintuitive that learning and automaticity can be dissociated, but they can.)