Electrical brain stimulation improves math skills

Life 4 November 2010

Are you bad at sums? Get muddled at the market? If so, you could benefit from a machine that improves your mathematical abilities. It’s not such a strange suggestion. Stimulating a particular area of the brain, it turns out, can improve numeracy for at least six months.

In 2007, Roi Cohen Kadosh at the University of Oxford and colleagues pinned down the area of the brain responsible for mathematical ability to the right parietal lobe, just above the right ear.

His team “short-circuited” this area using transcranial magnetic stimulation (TMS) – a stream of magnetic pulses which temporarily disables a targeted area of the brain. The result, they found, was that people’s ability to perform numerical tasks fell. In fact, their performance resembled people with dyscalculia, who have difficulty comprehending mathematics.

Now they have done the reverse, and improved the brain’s arithmetical abilities. To do this the team applied transcranial direct current stimulation (tDCS), a way of enhancing brain activity using an electric current, to the right parietal cortex while simultaneously using the opposite current to subdue activity in the left parietal cortex.


Number puzzle

tDCS changes the voltage across neurons and can make them more or less likely to fire. Cohen Kadosh’s team zapped volunteers while they were shown made-up symbols representing the numbers 1 to 9. Although the volunteers had no idea which symbols stood for which number at the start of the test, they gradually worked this out by performing tests in which they were asked which symbol was numerically higher than another, then, once they had given their answer, were given the correct answer.

After each session, which involved hundreds of such calculations, they were given tests to see how well they could perform mathematical calculations using the symbols. Those given tDCS learned the symbols faster and did better in the tests than those subjected to a sham procedure.

When the subjects were tested six months later, those who had been given tDCS still did better than those who hadn’t. “It is already known that tDCS affects neurotransmitters involved in learning, memory and plasticity, so we presume that these are being manipulated in this study to cause long-term changes in the brain,” says Cohen Kadosh.

While the results show an enhanced association between arbitrary symbols and numbers, they don’t necessarily isolate number skills because the effects of brain stimulation weren’t compared with a non-numerical task, says Christopher Chambers at the University of Cardiff, UK. “So while the results are exciting, I think it remains to be seen whether the effects are specific for numerical competence, or whether they translate to other abilities that depend on learning.”

Improved numeracy

“This isn’t going to turn you into a genius,” says Cohen Kadosh, “but it could be turned into a device to help children with poor numeracy skills improve their mathematical abilities”.

“I think this is a truly brilliant finding from an outstanding team and one which could have profound ramifications for future investigations of enhanced cognition by non-invasive brain stimulation,” says Allan Snyder, director of the Centre for the Mind at the University of Sydney, Australia, who was not involved in the study. “Repeated applications of tDCS are believed by some to have had a long-term effect on mitigating depression, so I am not altogether surprised by their finding of long-lasting effects.”

Journal reference: Current Biology, DOI: 10.1016/j.cub.2010.10.007

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