SAN DIEGO – Scientists have devised ways to “read” words directly from the brain. Brain implants can translate internal speech into external signals, allowing communication by people with paralysis or other diseases that rob them of the ability to speak or express themselves.
New results from two studies, presented on November 13 at the annual meeting of the Society for Neuroscience, “provide additional evidence of the extraordinary potential” of having brain implants to restore lost communication, says neuroscientist and neurocritical care physician Leigh Hochberg.
Some people who need help communicating today can use devices that require small movements, such as eye contact changes. Not all of these services are possible. Thus the new studies aimed at internal speech, which requires a person to think nothing else.
“Our device directly predicts internal speech, allowing the patient to focus only on saying the word inside their head and converting it into text,” said Sara Wandelt, a Caltech neuroscientist. Internal speech “can be much simpler and more intuitive than the patient’s words or mouth.”
Neural signals associated with words are detected by electrodes placed in the brain. The signals can then be translated into text, which can be heard by a speech-generating computer program.
That approach is “really exciting and reinforces the power of bringing together fundamental neuroscience, neuroengineering and machine learning approaches to restore communication and mobility,” says Hochberg, of Massachusetts General Hospital and Harvard School of Medicine in Boston, and at Brown University in Providence. , R.I
Wandelt and colleagues were able to accurately predict which eight words a person with paralysis below the neck was thinking. The man was bilingual, and investigators were able to detect words in both English and Spanish.
Electrodes picked up nerve cell signals in the posterior parietal cortex, an area of the brain involved in speech and hand movements. A brain implant there could one day be used to control machines that can perform tasks normally done by the hands as well, Wandelt says.
Another approach, led by neuroscientist Sean Metzger of the University of California, San Francisco and colleagues, relied on orthography. The participant was a man named Pancho who could not speak more than 15 years after the accident and the impact in the car. In his new studies Pancho did not use letters; but silently he tried to say the code words, such as “alpha” for A and “resonate” for E.
Narrowing these letters into words, man produced sentences such as “I don’t want” and “I know.” Each spelling session ended when the person attempted to express their hand, thereby creating a neural signal that would stop decoding. These results, presented at the Neuroscience meeting, were also published on November 8 Nature Communications.
This system allowed Pancho to produce about seven words per minute. This can make it faster than about five words per minute of current communication, but much slower than normal speech, usually about 150 words per minute. “That’s the speed we love to hit one day,” says Metzger.
To be useful, today’s technology will have to get faster and more accurate. It’s also unclear whether the techniques will work for other people, perhaps with more profound speech disorders. “It’s still early days for the technology,” Hochberg says.
The program will only be possible with the help of those who offer to study. “The field will benefit incredibly from those enrolled in clinical trials,” says Hochberg, “as their participation is absolutely vital to the successful translation of these early discoveries into clinical utility.”
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