According to a Nature story:
Connecting a battery across the front of the head can boost verbal skills, says a team from the US National Institutes of Health.
A current of two thousandths of an ampere (a fraction of that needed to power a digital watch) applied for 20 minutes is enough to produce a significant improvement, according to data presented this week at the annual meeting of the Society for Neuroscience, held in San Diego. And apart from an itchy sensation around the scalp electrode, subjects in the trials reported no side-effects…
The volunteers were asked to name as many words as possible beginning with a particular letter. Given around 90 seconds, most people get around 20 words. But when Iyer administered the current, her volunteers were able to name around 20% more words than controls, who had the electrodes attached but no current delivered. A smaller current of one thousandth of an amp had no effect.
Iyer says more work needs to be done to explain the effect, but she speculates that the current changes the electrical properties of brain cells in the prefrontal cortex, the brain region through which it passes. She believes that the cells fire off signals more easily after the current has gone by. That would make the brain area, a region involved in word generation, generally more active, she suggests.
Very interesting, but I think I’ll stick to my unaided verbality, thanks. (A tip of the hat to Songdog for the link.)