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Paralysis patients achieve fastest typing yet with new brain-computer interface

Improved technology allows patients to type up to eight words per minute, but not yet marketable

Even simple communication is a constant struggle for paralyzed patients, but a collaborative project from BrainGate neurotechnology researchers, which included scientists from Brown, recently found a way for these patients to type at the fastest speeds achieved yet.

Imagined actions, such as moving a cursor across an on-screen keyboard and selecting a letter, have become a reality for paralyzed patients with the help of a brain-computer interface.

Researchers implanted a tiny array of 100 electrodes in the brain so only the top of a silver plug was visible outside the patient’s skull. These electrodes recorded the firing of certain cells inside the brain and sent the information through a series of wires and connectors to reach a decoder — a computer system that interprets the information, said Leigh Hochberg ’90, professor of engineering.

The most recent data from the ongoing research shows that typing assisted by brain-computer interfaces is approaching speeds that would be useful for the public, Hochberg said. For patients who cannot move or speak, “even the ability to say yes or no is meaningful communication,” he added.

The three subjects were able to type at 1.4 to 4.2 times the speeds previously achieved by paralysis patients using similar systems, according to the study. With the interface, one subject reached a typing speed of nearly eight words per minute. All three typed at rates of about 2.5 words per minute, wrote Chethan Pandarinath, postdoctoral fellow at Stanford University and lead author of the study, in an email to The Herald.

Though these typing speeds are the fastest yet, they remain “painfully slow,” said Elizabeth Tyler-Kabara, director of the Neural Enhancement Laboratory at the University of Pittsburgh. Predictive typing systems, like those that complete your words and phrases as you text, might increase those speeds dramatically, she added.

Advances in machine learning and artificial intelligence could also enhance the interfaces, allowing for more natural control, Pandarinath wrote.

The interface is not yet a marketable device, said Paul Nuyujukian, director of the Brain Interfacing Laboratory at Stanford and co-author of the study. The interface needs to be able to work anywhere, without wires or a trained technician, he added.

Still, this increase in typing speed is “a hugely significant increase,” said Michael Boninger, vice chair for research at the University of Pittsburgh Medical Center. “There’s no doubt that this brain-computer interface work has the ability to be transformative.”

Researchers in multiple locations across the country have engaged in human research with this implanted chip since around 2004, Hochberg said. More recently, the team developed algorithms for the decoder that allowed subjects to point and click on a screen, he added.

BrainGate researchers and other experts not involved with the project noted the study’s reliance on the research participants. Through their generous feedback about the device, they allow scientists to help more people with paralysis in the future, Hochberg said.

The subjects are “heroic,” Nuyujukian said. “All of medicine owes them a huge debt of gratitude.”

An earlier version of this article stated that patients in the study could type at rates above 3.5 words per minute. In fact, they could type at rates of about 2.5 words per minute. The Herald regrets the error. 


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