Machine Design

Computer reads minds

A brain computer interface (BCI) could help patients who are paralyzed and unable to communicate but have normal electrical activity in their brains.

Users would simply "type" on a virtual keyboard using their brain waves, says University of South Florida psychologist Emanuel Donchin.

BCI can help patients who suffer from amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease) — a rare progressive neurological disorder that ultimately leads to a complete paralysis of voluntary muscles in all parts of the body; cerebral palsy; or patients "locked in" following a brain-stem stroke.

The technique captures and reports brain potential (ERP) activity that happens in response to a patient seeing a rare or "oddball" event. This "oddball paradigm" relies on response to deviant stimuli embedded in a series of standard stimuli, such as letters, symbols, and commands.

Both healthy and disabled volunteers, wearing electrodes on their scalp attached to the BCI, sat before a display that flashed in random sequence the 26 letters of the alphabet and other symbols and commands in a 6 6 matrix. Test subjects were able to operate a virtual keyboard based on EEG reactions to the oddball events at a rate of about one character every 26 sec. "Even this slow rate is welcome considering there is no other channel of communication," says Donchin. Some 15 ALS patients have successfully used the system, though many adjustments are still needed before it is ready for patients' homes.

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