They call it a neuroprosthesis, and although it’s only a single patient so far, the team at the University of California at San Francisco (UCSF) are hoping their device can help others. paralyzed people to communicate.
“To our knowledge, this is the first successful demonstration of direct decoding of complete words from the brain activity of a person who is paralyzed and unable to speak,” said Dr. Edward Chang, neurosurgeon at UCSF who led the research team.
“This has great promise for restoring communication by harnessing the brain’s natural speech machinery,” Chang said in a statement.
The team implanted an array of electrodes in the area of the brain that controls speech in a man who suffered a stroke that left him paralyzed and unable to speak at age 20.
“Her cognitive function was intact,” the team wrote in their report, published in the New England Journal of Medicine.
The man, now in his 30s, was asked to use limited vocabulary while the device was tuned using computer algorithms to translate the electrical activity of his brain. These words were then projected onto a computer screen.
The UCSF has a video of the man using the device. “Hello,” he is asked via a computer screen. “Hello,” comes the response, a few seconds later, also typed as text on the screen.
He was asked, “How are you today?” »The patient answers hesitantly:« I am doing very well.
“We decoded sentences of participant’s cortical activity in real time at a median rate of 15.2 words per minute, with a median word error rate of 25.6%,” the team wrote.
“We detected 98% of the participant’s attempts to produce individual words, and we ranked the words with 47.1% accuracy using cortical signals that were stable throughout the 81-week study period. The researchers said.
Eventually, the patient, who asked not to be identified, helped the team create a 50-word vocabulary including words such as “yes”, “no”, “family”, “clean” and “nurse”. . These have been extended to complete sentences such as “No, I’m not thirsty”.
This is not a permanent solution – the electrode is a large device that sits at the top of the head and cannot be used continuously. But it’s also not a one-time wonder, the researchers said.
“In previously reported brain-computer interface applications, the decoding patterns often require daily recalibration before deployment with a user,” the researchers wrote. This device, they said, was more stable.
“This is an important technological step for a person who cannot communicate naturally, and it demonstrates the potential of this approach to give voice to people with severe paralysis and speech impairments,” said David. Moses, a postdoctoral engineer in Chang’s lab who worked on the study.
“This essay is just the start. This is the very first participant in the trial and the first set of experiments in this trial to show that this is possible, ”Chang said.
“On the hardware side, we need to build systems that have higher data resolution to capture more information from the brain, and faster. On the algorithm side, we need to have systems that can translate these very complex brain signals into spoken words, not text but actually spoken, oral and audible words, ”he added.
“One of the most important priorities is probably to expand the vocabulary so that it is not limited to the 50 words that we started with, but something that is generalizable to all words in English, for example. We also need to make sure that what we see in this participant can be seen with other people for a larger patient population. “
Other teams have tried to help paralyzed people speak.
In 2017, a team from the University of Tübingen in Germany used a cap studded with EEG sensors to help patients with amyotrophic lateral sclerosis (ALS) paralyze simple thoughts.