Excitable

[Michael] Weisend, who is working on a US Defense Advanced Research Projects Agency programme to accelerate learning, has been using ... transcranial direct current stimulation (tDCS) to cut the time it takes to train snipers...

The mild electrical shock [to the brain] is meant to depolarise the neuronal membranes in the region, making the cells more excitable and responsive to inputs. Like many other neuroscientists working with tDCS, Weisend thinks this accelerates formation of new neural pathways during the time that someone practises a skill. ...

[Sidebar:]
Zapping your brain with a small current seems to improve everything from mathematical skills to marksmanship, but for now your best chance of experiencing this boost is to sign up for a lab experiment. Machines that provide transcranial direct current stimulation (tDCS) cost £5000 a pop, and their makers often sell them only to researchers.

That hasn't stopped a vibrant community of DIY tDCS enthusiasts from springing up. Their online forums are full of accounts of their home-made experiments, including hair-curling descriptions of blunders that, in one case, left someone temporarily blind.

The New Scientist on research into "flow".