Will Oremus writes about brain modification through tDCS:

Scientists have rediscovered a centuries-old procedure for supercharging your brain. Depending on how it’s used, it could improve anything from focus to motor control to mathematical or even moral reasoning. It’s simple. It’s relatively cheap. The known side effects are minimal. And it’s so easy that you can do it in your own home, anytime you want. All you need are a pair of electrodes and a power source.

Maybe. Incredible as it sounds, though, every claim in the paragraph above has been supported by experimental evidence. The procedure is called transcranial direct-current stimulation, or tDCS, and the idea has been around for 200 years, though it languished in disrepute until recently. The setup: You attach one electrode to your scalp above the part of the brain you’re trying to stimulate, and another electrode on the other side of your head, to complete the circuit. Then you turn on a milliampere or two of juice, and watch the mental sparks fly—figuratively, if you’re doing it right.

Applying the electrodes to the prefrontal cortex can improve learning and increase your working memory. Almost every expert who talks about tDCS will tell you, “Don’t try this at home.” But a lot of people are starting to do just that. And it’s no wonder, given the parade of amazing results that researchers have reported achieving on subjects in the lab. It seems like you can make people better at just about anything if you just put the electrodes in the right place. To name just a few of the findings:

• Applying them to the motor cortex canraise your threshold for pain and make you more adept with your nondominant hand.
• Position them above the posterior portion of the left perisylvian area (in right-handed people) and they can facilitate language acquisition.
• Stimulation of the parietal cortex can improve numerical reasoning.

The potential applications for tDCS (and a related technology called repetitive transcranial magnetic stimulation, which uses magnets to induce a current) range from healing to educating to killing. Doctors are experimenting with tDCS to treat severe depression and help stroke victims regain their speaking skills. Students in theory could use it to solve math problems or pick up Russian. Air Force researchers are using it to make people better at guiding killer drones, and DARPA has found it could improve snipers’ marksmanship.

Seems legit.

Seems better than drugs, but bioethicists are debating.

Duke philosophy professor and bioethicist Allen Buchanan told Ross Andersen in the Atlantic:

“The list of design flaws in human beings is pretty long, as it is in other organisms, and so to think that somehow we're at the summit of perfection and that we're stable is to have the wrong idea of human nature. The misleading assumption is that if we don't interfere, we're going to continue the way we are, and of course that goes completely contrary to everything we know about evolution. In fact it might turn out that the only way to prevent us from going extinct, or to prevent some great worsening of our condition, is to enhance some of our capacities.”

Oremus concludes:

But we should resist the urge to demonize either technology just because they feel wrong, or like cheating, and so to close the door to progress. What if it turns out that something like a tDCS “thinking cap,” goofy as it sounds, could not only make us sharper but help us to exercise greater self-control or make better decisions under pressure? Is that really possible? Would it be safe? Let’s find out! And until then, I’ll join the chorus: Kids, don’t try this at home.

Read more from this series: Human enhancement is giving us superpowers once reserved for comic-book heroes; technology is expanding our minds; brain-computer interfaces let you move things with a thought; choose your own sixth sense; steel yourself with a robotic exoskeleton; is China engineering genius babies?; and do smart pills really work?