An experimental brain implant has just helped a man with paralysis turn his thoughts into words

Researchers reported earlier this week that they had successfully implanted an experimental device in a man's brain, giving him the ability to generate words and sentences on a computer using only his thoughts. The man, diagnosed with paralysis, is otherwise unable to move or speak. The procedure was reported in The New England Journal of Medicine, where researchers explained that the device decodes signals in the man's brain that once controlled his vocal tract. At the moment, the man is limited to 50 words and communicates at a speed of about 15 words per minute (which is considered slower than natural speech). However, researchers believe the experiment provides opportunities to improve the device and its capabilities, NPR reports.

"This tells us that it's possible," Edward Chang, a neurosurgeon at the University of California, San Francisco, stated in an interview with the news outlet. "I think there's a huge runway to make this better over time." Chethan Pandarinath, an assistant professor in the Department of Biomedical Engineering at Emory University and Georgia Tech, added that the experimental device, in comparison to assistive devices currently available to those who could not communicate using brain circuits previously used for speech, would be of greater benefit. This is because such devices would be "more natural, and hopefully effortless."

At present, those diagnoses with paralysis or similar forms of disability typically rely on devices that use eye or head movements to spell out words one letter at a time. A small minority utilizes devices that allow them to control a computer cursor with only their thoughts. However, Chang's team wished to develop a device that was easier and faster to use. Prior to this experiment, he worked on a system designed to recognize brain signals associated with the intention to speak specific words. As per test results, the system worked in people who were still able to move and speak. Nonetheless, this did not prove that someone with paralysis could necessarily benefit from the findings.

"We didn't know if the speech commands in the brain would still work after 15 years," Chang stated, referring to the man who received the successful brain implant. "And even if we could revive those dormant brain signals for speech, could we actually translate those into full words?" In order to find out, the research team implanted sensors on the surface of the man's brain. Over several months, they studied the patterns of electrical activity produced when he attempted to speak 50 different words. Once the man could generate words on a computer screen, the researchers urged him to form coherent sentences. To improve accuracy, the team developed a program that analyzed the context of each word as it was added. Chang shared, "So, for example, if one word is just not decoded correctly, this autocorrect function can correct it."

Following months of testing, the man was able to reliably generate a word every four seconds, amounting to 15 words per minute. Normal speech is on the order of 120 to 150 words per minute, so Chang noted that there was room for improvement. According to Krishna Shenoy, a professor in the School of Engineering at Stanford University, the research team's device could greatly help thousands of people who have had a stroke or a traumatic brain injury, in addition to people with amyotrophic lateral sclerosis, also known more popularly as ALS.