PARIS: US researchers announced that a paralysed man who cannot talk or type could spell over 1,000 phrases using a neuroprosthetic device that transforms brain waves into complete sentences.
"Anything is possible" was one of the man's favourite lines to write, according to Sean Metzger of the University of California, San Francisco, the lead author of a new study on the subject (UCSF).
A team of UCSF researchers demonstrated last year that a brain implant known as a brain-computer interface could translate 50 fairly frequent words when a man attempted to speak them in full. In the latest study in Nature Communications, they could decipher his silent mime of the 26 phonetic alphabet letters.
"Therefore, if he wanted to say 'cat,' he would say charlie-alpha-tango," Metzger explained.
The data was then crunched in real-time by a spelling interface using language modelling to determine likely words or errors.
According to the study, the researchers were able to decode over 1,150 words, representing "almost 85 per cent of the information in natural English phrases." They projected that this vocabulary could be expanded to more than 9,000 words, "roughly the number of words that the average person uses in a year," Metzger said. The device decoded around 29 characters per minute at a 6% error rate. This corresponds to almost seven words each minute. As the first participant in the Brain-Computer Interface Restoration of Arm and Voice trial, the individual is referred to as BRAVO1. Now in his late 30s, he experienced a stroke at age 20 that left him unable to intelligible speech. However, his cognitive function remained intact. He typically interacts by poking at letters on a computer screen with a pointer attached to a baseball cap.
In 2019, a high-density electrode was surgically inserted on the surface of his brain over the speech motor cortex. Since then, they have been able to monitor, via a port implanted in his skull, the various electrical patterns produced as he attempts to utter different words or letters.