Device helps paralyzed man speak via screen
Researchers able to harness brain waves
In a medical first, 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 Wednesday, is an important step toward one day restoring more natural communication for people who can’t talk because of injury or illness.
“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’s exciting to think we’re at the very beginning of a new chapter, a new field.”
Today, people who can’t speak or write because of paralysis have very limited ways of communicating.
For example, the man in the experiment uses a pointer attached to a baseball cap that lets him move his head to touch words or letters on a screen. Other devices can pick up patients’ eye movements.
Recent experiments with mind-controlled prosthetics have allowed paralyzed people to shake hands or take a drink using a robotic arm — they imagine moving and those brain signals are relayed through a computer to the artificial limb.
Chang’s team built on that work to develop a “speech neuroprosthetic” — decoding brain waves that normally control the vocal tract, the tiny muscle movements of the lips, jaw, tongue and larynx that form each consonant and vowel.
Volunteering to test the device was a man in his late 30s who 15 years ago suffered a brain-stem stroke that caused paralysis and robbed him of speech. The researchers implanted electrodes on the surface of the man’s brain, over the area that controls speech.
A computer analyzed the patterns when he attempted to say common words such as “water” or “good,” eventually becoming able to differentiate between 50 words that could generate more than 1,000 sentences.