HEAD GAMES

ASEE Prism, Nov 2004 by Grose, Thomas K

BIOMEDICAL ENGINEERING

RESEARCHERS in St. Louis are having epilepsy patients play mind games, and the results may one day enable wearers of prosthetic devices to move their artificial limbs using only thoughts. The team, led by Washington University researchers, worked with an electronic grid that rests atop the brain and records electrocorticographic (ECoG) activity, or brain surface signals. That's an advance beyond using non-invasive electrodes outside the skull to measure what's called electroenccphalographic (EEG) activity. Four patients had the grids implanted for up to two weeks so neurologists could pinpoint what part of their brains were inducing seizures. But the Washington team also hooked the grids to one-dimensional computer games, and in less than an hour, the patients learned to move the game cursor using only thoughts, achieving between 74 and 100 percent accuracy. Patients using EEG signals to control the game took months to learn to move the cursor accurately. One doctor likened previous EEG tests to the Wright Brothers' plane. "With our results, we're flying around in an F-16 jet." Tests using 2-D games are now underway, "but it is too early to disclose results," explains Daniel Moran, a biomedical engineer at the school. The grid is small, 8 cm by 8 cm, thin and pliable, and didn't cause the patients discomfort, Moran says. The long-term effects of such an implant are still unknown. Moran calls the results a big step forward toward developing a "brain-machine interface . . . one of the hottest things going in biomédical engineering today." -THOMAS K. GROSE