Prepare to Be Shocked

The Atlantic

Several years ago, the Defense Advanced Research Projects Agency got wind of a technique called transcranial direct-current stimulation, or tDCS, which promised something extraordinary: a way to increase people’s performance in various capacities, from motor skills (in the case of recovering stroke patients) to language learning, all by stimulating their brains with electrical current. The simplest tDCS rigs are little more than nine-volt batteries hooked up to sponges embedded with metal and taped to a person’s scalp.