Stuart Gromley sits hunched over a desk in his bedroom, groping along the skin of his forehead, trying to figure out where to glue the electrodes. The wires lead to a Radio Shack Electronics Learning Lab, a toy covered with knobs, switches, and meters. Even though he’s working with a kiddie lab, Gromley, a 39-year-old network administrator in San Francisco, can’t afford to make mistakes: he’s about to send the current from a nine-volt battery into his own brain.
Gromley’s homemade contraption is modeled on the devices used in some of the top research centers around the world. Called transcranial direct current stimulation (tDCS), the technology works on the principle that even the weak electrical signals generated by a small battery can penetrate the skull and affect hot-button areas on the outer surface of the brain. In the past few years, scholarly research papers have touted tDCS as a non-invasive and safe way to rejigger our thoughts and feelings, and possibly to treat a variety of mental disorders. Most provocatively, researchers at the National Institute of Health have shown that running a small jolt of electricity through the forehead can enhance the verbal abilities of healthy people. That is, tDCS might do more than just alleviate symptoms of disease. It might help make its users a little bit smarter.
Say “electricity” and “brain” in the same sentence, and most of us flash on certain scenes from One Flew Over the Cuckoos Nest. But tDCS has little in common with shock therapy. The amount of current that a nine-volt battery can produce is tiny, and most of it gets blocked by the skull anyway; what little current does go into brain tissue tends to stay close to the electrodes. By placing these electrodes on the forehead or the side of the head, researchers can pinpoint specific regions of the brain that they’d like to amp up or damp down.
Gromley is one among a small clique of hobbyists who have been discussing the tDCS machine on the Web. Like ham-radio operators of the brain, they share advice with their fellow tinkerers. “I accidentally found a way to make GREY FLASHES IN MY VISION using a 9v battery. Don’t you try it,” says one hacker in an on-line forum. “Here’s how not to do it,” he adds, and then provides instructions.
Gromley has been suffering from bouts of depression since he was a teenager; antidepressant medication has only made him feel worse. Now he finds himself sitting before a Radio Shack kit, with sponge electrodes he bought on e-Bay affixed to his head — one on the temple area and one on the brow. When he flips on a switch, current runs from the battery through a resistor and then into wires and into his prefrontal cortex. He leans back in his chair with his eyes closed, wondering if he feels anything. That’s when he sees the flash — what he describes as a “horizontal lightning bolt” — that seems to arc from one side of his forehead to the other.
“No, that didn’t happen,” he thinks, and tries to calm himself. Then, a few minutes later, he shifts in his seat, the wires jiggling, and he sees lightning again. Gromley yanks off the electrodes and begins searching on Google, using keywords like “tDCS” and “flash” until he finds a study that reassures him: those spots of light were harmless.
