Studies show that mild electrical currents can accelerate a number of cognitive functions, such as learning and math. But researchers now say there are mental tradeoffs to doing so.
About a year ago, a research team led by Rol Cohen Kadosh showed that transcranial random noise stimulation (tRNS) makes people better at math. It works by enhancing the excitability of the brain, and it does so by unobtrusively applying random electrical noise to target regions of the cortex via stimulation electrodes placed on the surface of the scalp. The practice could eventually be used for rehab purposes (like restoring speech), or to improve other brain functions, such as learning.
But now the same researchers have discovered that there's a mental cost to cognitive enhancement when using transcranial electrical stimulation (TES). It appears that gains in one area of cognition are introducing deficits in another. It's the first study to show that a tradeoff exists when there's a gain in cognitive function.
Greg Miller from Wired explains how they reached this conclusion:
Cohen Kadosh and his colleague Teresa Iuculano investigated 19 volunteers as they learned a new numerical system by trial and error. The new system was based on arbitrary symbols: A cylinder represented the number five, for example, and a triangle represented the number nine. In several training sessions the volunteers viewed pairs of symbols on a computer screen and pressed a key to indicate which one represented a bigger quantity. At first they had to guess, but they eventually learned which symbols corresponded with which numbers.
All of the volunteers wore electrodes on their scalp during these training session. Some received mild electrical stimulation that targeted the posterior parietal cortex, an area implicated in previous studies of numerical cognition. Others received stimulation of the dorsolateral prefrontal cortex, an area involved in a wide range of functions, including learning and memory. A third group received sham stimulation that caused a slight tingling of the skin but no change in brain activity.
Those who had the parietal area involved in numerical cognition stimulated learned the new number system more quickly than those who got sham stimulation, the researchers report today in the Journal of Neuroscience. But at the end of the weeklong study their reaction times were slower when they had to put their newfound knowledge to use to solve a new task that they hadn't seen during the training sessions. "They had trouble accessing what they'd learned," Cohen Kadosh said.
A similar effect happened in those volunteers who had their learning and memory areas stimulated. According to Kadosh, work needs to be done to figure out how to minimize these effects.
This finding throws a bit of a wrench into the prospect of intelligence augmentation. As the researchers conclude in their study:
These findings have important implications for the future use of enhancement technologies for neurointervention and performance improvement in healthy populations.
It's important to note that these tradeoffs are specific to TES. Other interventions, like pharmaceuticals, may not produce the same effects.
And like I've argued before, we still don't know if cognitive enhancement is a good thing.
Image: Images: Michelangelus/Shutterstock.