From an article about the athletes' brains:

Unsurprisingly, most of the article is about elite athlete's brains being more efficient in using their skills and better at making predictions about playing, but then....

n February 2009 Krakauer and Pablo Celnik of Johns Hopkins offered a glimpse of what those interventions might look like. The scientists had volunteers move a cursor horizontally across a screen by pinching a device called a force transducer between thumb and index finger. The harder each subject squeezed, the faster the cursor moved. Each player was asked to move the cursor back and forth between a series of targets, trying to travel the course as quickly as possible without overshooting. The group trained 45 minutes a day for five days. By the end of training, the players were making far fewer errors.

The scientists also trained another group of people on the same game, but with a twist. They put a battery on top of the head of each subject, sending a small current through the surface of the brain toward a group of neurons in the primary motor cortex. The electric stimulation allowed people to learn the game better. By the end of five days of training, the battery-enhanced players could move the cursor faster and make fewer errors than the control group. And the advantage was not fleeting. For three months Krakauer and Celnik had their subjects come back into the lab from time to time to show off their game-playing skills. Everyone got rusty over time, but at the end of the period, the people who had gotten the electrode boost remained superior to the others.

I wonder whether there are similar brain differences between top mathematicians and everyone else, and if such a simple method could make people better at math.