SAN DIEGO — Scientists have devised ways to “read” words directly from brains. Brain implants are capable of translating internal speech into external signals. This allows people with paralysis and other disorders to communicate.
New results from two studies, presented November 13 at the annual meeting of the Society for Neuroscience, “provide additional evidence of the extraordinary potential” that brain implants have for restoring lost communication, says neuroscientist and neurocritical care physician Leigh Hochberg.
Devices that require very small movements, such eye gaze changes, are available for some individuals who need assistance communicating. Those tasks aren’t possible for everyone. The new research focused on internal speech, which requires that a person think.
“Our device predicts internal speech directly, allowing the patient to just focus on saying a word inside their head and transform it into text,” says Sarah Wandelt, a neuroscientist at Caltech. Internal speech “could be much simpler and more intuitive than requiring the patient to spell out words or mouth them.”
Implanted electrodes in the brain detect neural signals that are associated with words. These signals can then be translated to text using computer programs that create speech.
That approach is “really exciting, and reinforces the power of bringing together fundamental neuroscience, neuroengineering and machine learning approaches for the restoration of communication and mobility,” says Hochberg, of Massachusetts General Hospital and Harvard Medical School in Boston, and Brown University in Providence, R.I.
Wandelt’s colleagues and Wandelt were able predict which of eight words an individual paralyzed below their neck thought. The man was bilingual. The researchers were able to detect both English words and Spanish words.
The electrodes picked up signals from nerve cells in the brain’s posterior parietal cortex. This area is involved in speech and hand movements. Wandelt believes that the brain implant might be used to control devices that are able to perform tasks typically performed by a human hand.
One approach that was led by Sean Metzger (University of California, San Francisco) and his colleagues relied on spelling. The participant was a man called Pancho who hadn’t been able to speak for more than 15 years after a car accident and stroke. In the new study, Pancho didn’t use letters; instead, he attempted to silently say code words, such as “alpha” for A and “echo” for E.
By stringing these code letters into words, the man produced sentences such as “I do not want that” and “You have got to be kidding.” Each spelling session would end when the man attempted to squeeze his hand, thereby creating a movement-related neural signal that would stop the decoding. These results were also presented at a neuroscience meeting. PubliziertNovember 8, 2009 Nature Communications.
Pancho could produce approximately seven words per hour using the system. That’s faster than the roughly five words per minute his current communication device can make, but much slower than normal speech, typically about 150 words a minute. “That’s the speed we’d love to hit one day,” Metzger says.
Current techniques must be faster and more precise in order to be useful. It’s also unclear whether the technology will work for other people, perhaps with more profound speech disorders. “These are still early days for the technologies,” Hochberg says.
People who are willing to participate in the studies will make progress. “The field will continue to benefit from the incredible people who enroll in clinical trials,” says Hochberg, “as their participation is absolutely vital to the successful translation of these early findings into clinical utility.”
