A device that clicks on brain waves to help a paralyzed man communicate

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In the first medical experiment, researchers harnessed the brain waves of a paralyzed man unable to speak – and turned what he intended to say into sentences on a computer screen.

It will take years of additional research, but the study, reported on Wednesday, represents an important step toward restoring more normal communication someday for people who cannot speak due to injury or disease.

“Most of us take for granted how easily we communicate through speech,” said Dr. Edward Chang, a neurosurgeon at the University of California, San Francisco, who led the work. “It is exciting to think we are at the beginning of a new chapter, a new field” to mitigate the devastation of patients who have lost this ability.

Today, people who cannot speak or write because of paralysis have very limited ways of communicating. For example, a man in the experiment, who has not been identified to protect his privacy, uses a pointer attached to a baseball cap that allows him to move his head to touch words or letters on the screen. Other devices can pick up the patient’s eye movements. But it is a frustrating and limited alternative to speech.

Tapping on brain signals to overcome disability is a hot field. In recent years, experiments with mind-controlled prosthetics have allowed paralyzed people to shake hands or have a drink with a robotic arm – imagining they are moving and those brain signals being transmitted via a computer to the prosthesis.

Zhang’s team relied on this work to develop a “neuro orthotics of speech” — the decoding of the brain waves that naturally control the vocal tract, and the small muscle movements in the lips, jaw, tongue and larynx that make up each consonant and vowel.

Volunteering to test the device was a man in his late 30s who, 15 years earlier, had suffered a stroke that caused widespread paralysis and left him speechless. The researchers implanted electrodes on the surface of the man’s brain, over the area that controls speech.

The computer analyzed the patterns when it tried to say common words like “water” or “good,” and eventually was able to distinguish 50 words that could generate more than 1,000 sentences.

prompted with questions such as “How are you today?” or “Are you thirsty,” the device eventually enabled the man to answer “I’m very good” or “No I’m not thirsty” — without uttering the words but translating them into text, the team reported in the New England Journal of Medicine.

It takes about three to four seconds for the word to appear on the screen after the man tries to pronounce it, said lead author David Moses, an engineer in Chang’s lab. This is not as fast as talking but faster than eavesdropping to reply.

In an accompanying editorial, Harvard neuroscientists Lee Hochberg and Sydney Cash described the work as a “groundbreaking demo.”

They suggested improvements but said that if the technology eventually solves them, it could help people with injuries, strokes or diseases such as Lou Gehrig’s disease whose “brains prepare messages for delivery but those messages are trapped”.

Chang’s lab has spent years mapping the brain activity that leads to speech. First, the researchers temporarily placed electrodes into the brains of volunteers undergoing surgery for epilepsy, so they could match brain activity to spoken words.

Only then is it time to experience the experience with someone who is unable to speak. How did they know that the device interpreted his words correctly? They started by making him try to say specific sentences like, “Please bring my glasses,” instead of answering open-ended questions so the machine translates accurately most of the time.

The following steps include ways to improve the device’s speed, accuracy, and vocabulary volume – and perhaps one day allow computer-generated voice instead of on-screen text – while testing a small number of additional volunteers.

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The Associated Press’s Department of Health and Science receives support from the Howard Hughes Medical Institute’s Division of Science Education. AP is solely responsible for all content.

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