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Stanford University School of Medicine

Pure brainpower directs onscreen cursor, letting paralyzed people type

Millions of people are living with paralysis in the United States alone. Sometimes their paralysis comes gradually, as occurs in amyotrophic lateral sclerosis, also called Lou Gehrig's disease.

Sometimes it arrives suddenly, as it did for Dennis Degray.

In a news release about an astonishing new study published in eLife, I wrote:

Now 64, Degray became quadriplegic on Oct. 10, 2007, when he fell and sustained a life-changing spinal-cord injury. "I was taking out the trash in the rain," he said. Holding the garbage in one hand and the recycling in the other, he slipped on the grass and landed on his chin. The impact spared his brain but severely injured his spine, cutting off all communication between his brain and musculature from the head down. "I've got nothing going on below the collarbones," he said.

But now, a brain-to-computer hookup has enabled Degray and two other people with paralysis due to ALS to type via direct brain control at speeds and accuracy levels beginning to approach those of people with full use of their musculature.

In a study led by Stanford bioengineer Krishna Shenoy, PhD, and neurosurgeon Jaimie Henderson, MD, (who discuss the work in the video above), the three participants with severe limb weakness had one or two baby-aspirin-sized electrode arrays placed in their brains to record signals from the brain region controlling muscle movement, so that neural signals from that brain region could be transmitted to a computer via a cable and translated by algorithms into point-and-click commands guiding a cursor to characters on an onscreen keyboard.

After minimal training during which they were encouraged to attempt or visualize patterns of desired arm, hand and finger movements, the participants were asked to copy phrases and sentences such as, "The quick brown fox jumped over the lazy dog." They achieved average rates of 7.8, 6.3 and 2.7 accurately typed words per minute, respectively. (At nearly 8 wpm, Degray was the champion typist.)

For comparison, able-bodied people's typical typing rates on smartphones range from 12 to 30 words per minute. And notably, the study participants achieved these typing rates without the use of automatic word-completion assistance common in electronic keyboarding applications nowadays, which undoubtedly would have boosted their performance.

The study's success "marks a major milestone on the road to improving quality of life for people with paralysis," says Henderson.

Shenoy thinks the day will come -- and closer to five than 10 years from now, he predicts -- when a self-calibrating, fully implanted wireless system can be used without caregiver assistance, has no cosmetic impact and can be used around the clock.

"I don't see any insurmountable challenges," he says. "We know the steps we have to take to get there."

Degray, who knew how to type before his accident but was no expert at it, describes his newly revealed prowess in the language of a video game aficionado: "This is like one of the coolest video games I've ever gotten to play with. And I don't even have to put a quarter in it."

Previously: Technology for typing with brain signals could allow paralyzed people to communicate, Stanford researchers provide insights into how human neurons control muscle movement and Stanford conducts first U.S. implantation of deep--brain-stimulation device that monitors, records brain activity
Photo of Krishna Shenoy and Jaimie Henderson by Paul Sakuma

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