The researchers presented their findings at the 2009 annual meeting of the American Epilepsy Society.
Jerry Shih, one of the scientists from the Mayo Clinic campus in Jacksonville, Fla. who collaborated on the project, cautioned that the test "constitutes a baby step." Still, it marked another advance toward the day when people suffering from spidal cord injuries can make use of assistive devices controlled by a brain-computer interface. In fact, HPlus Magazine noted that Dr. Gerwin Schalk, who worked with patients using electrocorticography, or ECoG, at the Wadsworth Center, in Albany, NY., has conducted a similar study.
In the Florida experiment, two patients who had had electrodes placed on the surface of their brains to monitor their seizure activity, were used to test out a prototype interface developed by Shih's team. The researchers made the correct hunch that this would provide a cleaner signal than when electrodes are placed on the scalp, as is done during an electroencephalography, or EEG.
"The scalp and bony skull diffuses and distorts the signal, rather like how the Earth's atmosphere blurs the light from stars," Shih said of data collected from EEGs. "That's why progress to date on developing these kind of mind interfaces has been slow."
The patients were connected to a computer, which was fashioned to make sense of electrical signals emanating from the electrodes. Each time they focused on a flashing letter on screen, the computer would record their brains' response. Researchers then asked them to focus on specific letters, and the computer software recorded that information as well.
"We were able to consistently predict the desired letters for our patients at or near 100 percent accuracy," Shih said. "While this is comparable to other researchers' results with EEGs, this approach is more localized and can potentially provide a faster communication rate. Our goal is to find a way to effectively and consistently use a patient's brain waves to perform certain tasks."
Mayo Clinic researchers also worked on the study with Dean Krusienski from the University of North Florida.