A New Brain Implant Lets You Transform Thoughts Into Speech

Science is working to restore the natural faculties we often lose in life.

And a man without the power of speech or movement can generate words and sentences on a computer with thoughts alone, thanks to a new experimental implant that decodes brain signals that work the vocal tract, according to a recent study published in the journal The New England Journal of Medicine.

Crucially, the method behind this novel implant could radically increase the number of words per minute a person with paralysis may communicate.

The paralyzed test subject lost the power of conventional speech in a stroke

As of writing, the man only has a vocabulary of 50 words, and can communicate at a slow pace of 15 words per minute, which is obviously far slower than conventional speech. "This tells us that it's possible," said the neurosurgeon Edward Chang of the University of California, San Francisco, in an NPR report. "I think there's a huge runway to make this better over time." 

The researchers speculated that a device designed to use the part of the brain conventionally used for speech might be "more natural, and hopefully effortless compared to current assistive devices," explained Assistant Professor Chethan Pandarinath of Emory University' department of biomedical engineering, in addition to Georgia Tech, in the report. Modern-day devices rely on head or eye motion to help people suffering from paralysis communicate and spell out words. A handful even enable users to control a computer cursor using their thoughts, alone.

This is better than nothing, but Chang's team wanted to build a better solution to bring back some communicative capabilities for a man they humanely designated BRAVO1 (for anonymity's sake). The "code" name refers to his eminent status as the first of more forthcoming subjects for a study dubbed BRAVO, which stands for Brain-Computer Interface Restoration of Arm and Voice. BRAVO1 is in his late 30s, and has suffered paralysis that keeps him from speaking since a serious stroke befell him, 15 years ago.

The new BCI method aims to reach 50 or more words per minute

"The stroke left him nearly completely paralyzed in his arms and legs but also in the muscles of his vocal tract," said Chang. While this put an end to his organic ability to speak, the region of his brain that commanded speech remained perfectly fine. Thinking on how to leverage this, Chang's team turned to a system they designed to identify the brain signals linked with a personal will to speak disparate words. Tests have shown this system functions in people who retained their locomotive and vocal capabilities. All that remained was to test it on someone who hadn't. Someone like BRAVO1.

"We didn't know if the speech commands in the brain would still work after 15 years," said Chang, in the report. "And even if we could revive those dormant brain signals for speech, could we actually translate those into full words?" Lacking answers, the team implanted sensors on the surface of Mr. BRAVO1's brain. Then a computer linked to the sensor analyzed patterns in the electrical activity generated when he tried to utter 50 different words. And this didn't happen in a flash: It took entire months to complete.

After a while, BRAVO1 learned how to reliably produce words on a computer screen, so the team assigned a new challenge: sentences. Accuracy was lacking at first, so the team slapped on a new program designed to evaluate the context of every word as the man tried to say them. In a way, it's not unlike the texting software on your smartphone. "So, for example, if one word is just not decoded correctly, this autocorrect function can correct it," said Chang in the report. BRAVO1, along with the new Brain-Computer Interface, has come far. But until the 14 words per minute are improved to 50 words per minute (and beyond), more research is needed to help people like the first man of BRAVO study reacquire the critical human power of seamless communication.