A light electrical current just above the right ear seems to improve numerical learning for at least six months, according to a new study. But if the current is moved to the left side, average peoples' ability to learn basic numerical principles plummets.

The group behind the new study, led by Roi Cohen Kadosh, a cognitive neuroscientist at the University of Oxford's Department of Experimental Psychology, found that 20 minutes of transcranial direct current stimulation (TDSC) trained on a particular place on the scalp—coupled with training sessions—boosted healthy adults' ability to learn and use nine new numerical symbols (though it did not seem to affect manipulation of familiar numbers).

Researchers think that the electrical pulses are triggering molecular changes in the brain, such as neurotransmitters and their receptors—especially those involved in learning. Stimulation was targeted to the two parietal lobes, which are known to be involved in sensory, perceptual and numerical processing.

Previous work by other groups has shown that TDCS to seems to improve memory in some patients, but as Cohen Kadosh points out, those experiments targeted a different part of the brain than his team's research.

For the new experiment, Cohen Kadosh and his colleagues assigned 15 healthy adult subjects into one of three different groups: one received 20 minutes of TDSC to the right parietal lobe, another got 20 minutes of TDSC (at a current of one milliamp) on the left parietal lobe, and a third received only 30 seconds of electrical stimulation in a procedure to act as the control group. (The procedure is relatively painless, Cohen Kadosh explains, and subjects only notice a slight tingling for 15 to 30 seconds and then acclimate to the sensation and cease to notice it, thus making the sham group a fairly reliable control in this case.)

In the midst of the electric stimulation pulses, each group underwent a 90-120 minute training session six days in which they were to learn a new group of symbols and their relative value (without the symbols being explicitly equated to known numbers). After each training session, the subjects were then tested with different tasks, such as lining the values up in order, to assess progress in learning the new symbols. The group that got juiced along their right parietal lobe learned the symbols more thoroughly than the sham group—and much more thoroughly than the group that got the left parietal lobe treatment, which showed little to no learning at all. And after bringing the right parietal lobe group back into the lab six months later, the researchers found that subjects had maintained their newfound (if fictitious)  numeracy. The findings were published online November 4 in Current Biology.

But why not test the procedure with real numbers? "I cannot take an adult who already knows how to process numbers in a normal way" and try to assess their ability to learn the skills anew, Cohen Kadosh explains. Novel mathematical symbols can help mimic the process of learning basic numerical concepts.

Cohen Kadosh and his colleagues note that a TDCS brain boost could help children who are struggling to learn early number skills or adults who have lost that function through stroke or even age-related cognitive decline.

Thus far, the procedure showed no negative side effects, nor did it seem to drain other mental resources, Cohen Kadosh says. "But before we're going to apply it to children and make it a therapeutic tool for adults, we want to take a really good, careful look at it."

The treatment could also someday possibly be helpful for the 6 percent or so of healthy adults with severe developmental dyscalculia (a diagnosis for people who have trouble with basic number-based logic) or the 20-odd percent of people who have some innumeracy. These difficulties can include problems counting change or adding single digit numbers, Cohen Kadosh explains, "they're using their fingers" and other "very immature strategies to solve this task."

What about those of us who just feel so-so about our competence with calculus? Is an appointment with a magic math-skills stimulator going to be an option for us—or our offspring? It is unclear if this procedure can improve the everyday math skills of average adults. In fact, when the researchers tested the subjects' real-number manipulation abilities on the last day of TDCS-boosted training, they found no change in any of the groups. So the cranial charge might best address the most basic apprehension of number relationships, rather than zapping a normal student to Newton-level numeracy.

Many people have also debated the broader merits of brain-boosting strategies. "There are a lot of ethical questions—whether it is justified or not and whether people with average mathematical abilities can use tools for cognitive enhancement," Cohen Kadosh says. Those are "questions that the public—and scientists—should deal with." But in the end, perhaps it will be a simple calculation of broader reward: perhaps electrical juicing for someone with average or above average numerical abilities to begin with would allow them to become a super-scientist, Cohen Kadosh says, resulting in someone who "would be able to contribute to the society where we live and make it a better place."

Image courtesy of iStockphoto/dra_schwartz