Article here;
http://www.ox.ac.uk/media/science_blog/brainboosting.html
Recent research in Oxford and elsewhere has shown that one type of brain stimulation in particular, called transcranial direct current stimulation or TDCS, can be used to improve language and maths abilities, memory, problem solving, attention, even movement.
Critically, this is not just helping to restore function in those with impaired abilities. TDCS can be used to enhance healthy people’s mental capacities. Indeed, most of the research so far has been carried out in healthy adults.
The article goes on to discuss the ethics of the technique.
The example of math learning seemed pretty contrived to me. Here is an 8 year old article on transcranial stimulation for drawing. If nothing else, look at the drawings made by the journalist.
The Sydney work is about magnetic stimulation, while the Oxford work is electrical, but the effects sound pretty similar. Electrical techniques are cheaper, but harder to control (2d vs 3d). The drawing article appeared in the New York Times Magazine, but the current web page lacks the drawings.