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Researchers say they used brain waves from a paralyzed man who cannot speak to produce words from his thoughts on a computer.
A team led by Dr. Edward Chang of the University of California at San Francisco performed the experiment. The results of the study were published on July 15 in the New England Journal of Medicine.
“Most of us take for granted how easily we communicate by word of mouth, ”Chang told The Associated Press. “It’s exciting to think that we are at the very beginning of a new chapter, a new area” to ease the difficulties of patients who have lost this ability.
Researchers admit that such methods of communication for paralysis victims will require years of additional research. But, they say, the new study marks an important step forward.
Today, the paralyzed who can neither speak nor write have very limited means of communication. For example, the man in the experiment used a pointer attached to a hat that allows him to move his head to touch words or letters on a screen. Other devices can pick up a person’s eye movements. But such methods are slow and replace very little speech.
The use of brain signals to bypass disabilities is currently a hot area of study. In recent years, experiences of mind control prostheses allowed paralyzed people to shake hands with someone or have a drink using a robotic arm. The process involves people imagining movements and these brain signals are sent via a computer to the prosthesis.
Chang’s team built their experience on previous work. They developed a method called “speech neuroprosthetics”. The process uses brain waves which normally control the vocal tract or the vocal system. This includes the small muscle movements of the lips, jaw, tongue, and larynx that make up each consonant and vowel.
The person who volunteered to test the device was a man in his thirties. He suffered from a brainstem stroke 15 years ago, this caused generalized paralysis and left him unable to speak.
The researchers implanted electrodes on the surface of the human brain, in the area that controls speech. A computer observed the patterns when trying to pronounce common words such as “water” or “good”. Over time, the computer has become able to differentiate 50 words that can make more than 1000 sentences.
Repeated questions such as “How are you today?” Or “Are you thirsty”, the device allows the man to respond “I am very well” or “No, I am not thirsty”. The words were not spoken, but were turned into text on the computer.
It takes about three to four seconds for a word to appear after the man tries to say it, study senior editor David Moses said. He’s an engineer in Chang’s lab. Although this rate is not as fast as speaking, it is faster than current methods.
In an opinion piece published with the study, Harvard brain doctors Leigh Hochberg and Sydney Cash called the work “innovative demonstration.”
Both doctors said the technology could one day help people with injuries, strokes or illnesses like Lou Gehrig’s. People with such diseases have brains that “prepare messages for delivery, but these messages are trapped, ”they wrote.
The researchers say their next steps will be to find ways to improve the speed, accuracy and vocabulary size of the device. They also plan to someday develop a computer-produced voice that could replace text on a computer.
I am Bryan Lynn.
The Associated Press reported this story. Bryan Lynn adapted the report for VOA Learning English. Caty Weaver was the editor.
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Words in this story
paralyzed – adj. unable to move or feel any part of the body
take for granted – phr. Valuing something too lightly
prosthetic – m. an artificial device that replaces a missing or injured part of the body
stroke – m. a sudden problem in the brain that changes blood flow and makes you unable to move part of your body
diagram – not. a particular way that something is often done or repeated
pioneer – m. a person who helps create or develop new ideas, methods
deliver – v. transport or send from one place to another
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