"Transcranial direct current stimulation (tDCS) is a safe and non-invasive method of temporarily altering the activity of neurons by passing weak currents through electrodes on the scalp. It can enhance mathematical skills, memory, attention and language learning."
http://www.newscientist.com/article/dn20080-zapping-the-brain-sparks-bright-ideas.html
"Transcranial direct current stimulation (tDCS) is a safe and non-invasive method of temporarily altering the activity of neurons by passing weak currents through electrodes on the scalp. It can enhance mathematical skills, memory, attention and language learning."