Stimulating the brain with a nonpainful electrical current can jump-start peoples' math skills, scientists say.
The finding could lead to new, long-lasting treatments for people with moderate to severe math impairments such as dyscalculia, or "math dyslexia." This learning disability prevents a person from grasping even simple math concepts, according to study leader Roi Cohen Kadosh, a neuroscientist at the University of Oxford in the U.K.
Treating such conditions is "exactly our aim," Cohen Kadosh said.
The team used a noninvasive method called transcranial direct current stimulation to apply a weak current to the brains of 15 healthy adult volunteers for six days as they took part in a learning task. The current was applied using pads on the scalp.
The subjects, who had normal mathematical abilities, were first trained to mentally associate nine random symbols with numbers.
This was done to mimic the learning process that children go through as they first learn how to associleate numerical values with digits, Cohen Kadosh said.
During each daily training session, the study participants received a 20-minute-long electrical stimulation to their parietal lobes, the part of the brain that is crucial for processing numbers. (See brain pictures.)
"People with dyscalculia have problems [in that brain region], such as lower brain activation or abnormal structures," Cohen Kadosh said.
Following each training, the researchers had the participants take tests that have been shown in children to correlate with mathematical achievements later in life.
In one test, participants were shown two of the symbols they had learned on a screen. One of the symbols might represent the number two and the other the number four. However, the two symbol would be intentionally bigger than the four symbol.
The researchers then asked the participants which "number" was physically larger, the 2 symbol or the 4 symbol.
People with normal mathematical abilities have trouble with this task, though very young children and people with dyscalculia don't, Cohen Kadosh explained.
That's because in normal brains, different mental processes—in this case size and evaluating numbers—interfere with one another.
(See "Mental Math Linked to Eye Motion, Brain Scans Show.")
When the participants' brains were electrically stimulated, their performance in the task worsened—proving that their math skills had improved.
"It's counterintuitive," Cohen Kadosh said, but declining performance is a sign that the number symbols have become deeply ingrained in the participants' minds—thus showing the treatment actually improved mathematical abilities.
Brain Boost is Long-Lasting
When the team tested the participants again six months later, they were surprised to find that the participants still performed poorly on the task—meaning the "improvements" were still present.
"The effect had worn off only slightly, but it was not significantly lower than after the end of the last training session," said Cohen Kadosh, whose study will appear November 23 in the journal Current Biology.
Scientists don't fully understand how electrical stimulation enhances certain mental abilities, but one possibility is that the current influences brain chemicals called neurotransmitters.
For example, electrical stimulation might reduce the effects of certain neurotransmitters that either interfere with or help with learning.
Whatever the reason, the team hopes that eventually their findings can help people with dyscalculia or those who have reduced math proficiency as a result of a stroke or degenerative disease.
But such treatments are most likely "very, very far off," said Daniel Ansari, a neuroscientist at the University of Western Ontario in Canada.
"This is an exciting beginning, but the experiment is limited to some very basic tasks," said Ansari, who was not involved in the study. "It doesn't necessarily show that it improves school-relevant learning skills" such as arithmetic.
Enhanced Math Skills an Ethical Dilemma
Routine brain-stimulation in people without developmental disorders would also raise ethical questions, said study leader Cohen Kadosh.
For example, a normal person without a disability who stimulates his or her brain to boost math prowess might be giving themselves an unfair advantage.
"Should we prevent this?" he said. "It's a dilemma, and an ethical question."