In the late 1990s, a team at the University of Göttingen enlarged the electrodes and covered them with sponges in order to allow more current to pass through the skull. They also created new protocols for placement of the electrodes. Just a few years ago, these design changes began to pay off in studies that showed promising results: the new, improved battery treatment could quicken the tongue and the hand. It could make people smarter and faster, if only by a small margin. When German researchers trained the positive electrode on the motor cortex, their human subjects became significantly faster at learning to hit a keyboard in response to a visual cue.
Meanwhile, NIH researchers found that people with their heads hooked up to batteries performed better on verbal tests. There is the promise, then, that portable machines could juice up particular spots in the brain. But would a brain-pod make you smarter than an ordinary cup of coffee? That’s still unclear.
Ride ’em Ronco
Picture your brain as a forest in the summer, all dry timber and secret layers of leaves. One stray match and fire will flare through it, consuming every tree. This is the metaphor that Yousef Mohammad uses to describe a migraine headache: a stray spark sets off a flame, and soon a whole area of the brain is burning. “We now believe the migraine starts with some kind of neuronal hyper-excitability” and that this small flare-up of neurons kicks off a chain reaction, says Mohammad, a neurologist at the Ohio State University Medical Center. He thinks he has found a way to halt the migraine before it rages out of control: a machine the size of a Kleenex box, with handles. It has already proved itself in a study of 43 patients. Now Mohammad is preparing to test the machine on 200 migraine sufferers; if it continues to show a significant ability to alleviate pain and nausea, it could hit the market within two years. The machine delivers two pulses of TMS to the back of the head. Because the pulses are discrete, rather than repetitive, there is no danger of triggering a seizure. These pulses, Mohammad says, work like a firebreak in a forest, creating a barrier to stop the conflagration. But of course, in this case it’s not fire but electricity that’s out of control. “We’re treating electricity with electricity, rather than treating electricity with medications,” according to Mohammad.
The same principle — of interrupting errant nerve signals before they cause a firestorm — could be used to treat chronic pain and depression with battery-powered electrodes. For instance, someone with chronic pain could use a tDCS machine to zap his or her motor cortex regularly over a period of weeks. The electric current would help to control signals near the surface of her brain, which in turn would help to quiet the thalamus. In a patient with chronic pain, the thalamus shrieks its message — ouch! ouch! ouch! — like a car alarm that doesn’t know how to shut itself off. This year, researchers at the Harvard Center for Noninvasive Brain Stimulation, working with colleagues in Brazil and Germany, published results of a preliminary experiment that showed tDCS could in fact provide relief for people with spinal cord injuries. In addition, Harvard researchers, along with their colleagues, also released the results of a preliminary study on depression: daily sessions of tDCS led to statistically significant boosts of mood in people diagnosed with major depression.