Using thought alone and with some electrodes placed on the surface of the brain, four volunteers were able to control a video game, U.S. researchers reported on Monday.

Simply by thinking the word “move,” the volunteers played the simple video game, the researchers reported.

“We are using pure imagination. These people are not moving their limbs,” said Dr. Eric Leuthardt, a neurosurgeon at Barnes-Jewish Hospital in St. Louis who worked on the study.

Their findings add to work being done at several centers and are aimed at finding ways to help people control computers or machines using brainpower alone. Potentially, people paralyzed by disease or accidents could use such devices to work, read, write and even possibly to move around.

Leuthardt said they tested four patients with epilepsy.

“These electrodes are placed on peoples’ brains on a routine basis for seizure localization,” Leuthardt said in a telephone interview.

The patients have their skulls opened and the electrodes placed on the surface of the brain to find out where their seizures are originating, so the connections in that area can be cut in the hope of a cure.

“We piggy-backed our study on that,” Leuthardt said.

Other researchers have worked with implanted electrodes in both monkeys and humans, but Leuthardt said this approach does not require putting anything deep into the brain.

“There is the potential for it to be very much less invasive,” he said.

Writing in Monday’s issue of the Journal of Neural Engineering, Leuthardt and Daniel Moran, an assistant professor of biomedical engineering at Washington University in St. Louis, said the patients learned in minutes how to control a computer cursor.

“It took six minutes of training and they all achieved control in less than 24 minutes,” Leuthardt said.

“After a brief training session, the patients could play the game by using signals that come off the surface of the brain,” added Moran. “They achieved between 74 and 100 percent accuracy, with one patient hitting 33 out of 33 targets correctly in a row.”

During the study their patients were forced to stay in bed tethered to a computer for up to two weeks, but Moran and Leuthardt hope to develop electrodes that can transmit signals without physical connections.

“You can’t keep wires directly from the brain to the outside world indefinitely because of the increased risk of infection,” Leuthardt added. “We have to create a wireless system.”

Leuthardt and Moran centered about 32 electrodes over the sensory motor cortex of the brain and a region called Broca’s area, which is associated with speech.

The pair did their work on a small amount of money - about $20,000 for the whole study, they said. “We really built this from matchsticks and paperclips,” Moran said.

“There will have to be a rigorous study on monkeys for an indeterminate number of years before we can consider permanent implants in human subjects, but we’re really excited about this advance,” he added.

A team at Duke University in North Carolina reported in March they had used electrodes implanted deep in the brains of Parkinson’s disease patients to transmit signals that might someday be used to operate remote devices.

SOURCE: Journal of Neural Engineering, June, 2004.