A computer extracts words from the brains of paralyzed people and makes them “speak” again

Two new brain-computer interfaces (BCIs) have succeeded in recognizing words in the brains of paralyzed people and then writing them on the screen. In this way, the patients were able to communicate again at a rate of more than 60 words per minute, much faster than had been possible until now.

The patients gained access to a vocabulary of 125,000 words, with the computer displaying the correct word in 76 percent of cases. And with a limited number of words, the accuracy rose to more than 90 percent.

“A significant advance” and “a turning point in the development of BCI technology aimed at restoring connectivity in paralyzed people,” says neuroscientist Nick Ramsey of the Brain Center at UMC Utrecht, who was not involved in the research. He stresses that communication is a basic human need, which some people are deprived of due to neurological disorders.

In the first study, 253 electrodes were implanted in a patient whose speech had become slurred by a stroke. A neural network analyzed her brain activity and converted it into sentences. After more than a week of training for just under two and a half hours, this resulted in a speed of 78 words per minute. For comparison: in an average conversation, you pass about 160 words per minute.

BCIs are used to convert an attempt to speak into words. “So thoughts aren’t converted into words, and it’s not thought-reading,” Ramsey says. “We’re looking at the output terminal in the brain that controls the muscles. So that part still has to work.”

“This is particularly interesting for people with ALS,” says Ramsey. “But people who have a certain cerebral hemorrhage, or who have brain damage, or who have partial paralysis, can also use it. We’ve done research and in the Netherlands it will affect about 150 to 200 people. Worldwide, it’s about thousands people”.

Hanno Bos is one of the patients in the Netherlands who benefits from the new method:

The technology used is not yet suitable for all paralyzed people. Patients in these studies could still mimic their own speech. So there are still weak muscle movements. Scientists will have to find a way to train people who are completely paralyzed. Sometimes these patients, who are called closed patients, are able to communicate only by moving their eyes.

In addition, wireless BCIs may be desirable for cosmetic reasons. At this point, the electrodes in the brain are still connected to the external computer. “These studies are diamonds in the rough,” Ramsey concludes. “I call it a Ferrari block with no car around it. That car is yet to come.” Many researchers around the world are working on developing this “car”, including Ramsey’s research group at UMC Utrecht.