Emily Chan
A 45-year-old man with ALS, also known as amyotrophic lateral sclerosis or, more commonly, Lou Gehrig’s disease, has regained speech thanks to a brain-computer interface (BCI) equipped with cutting-edge AI technology. It can decode his speech with about 97 percent accuracy and read aloud in his real voice.
Casey Harrell had been struggling with verbal communication due to the muscle weakness caused by his condition, leading to him developing dysarthria.
Harrell is among a handful of patients participating in the BrainGate clinical trial. They are testing out new BCIs that aim to give back their voices and restore their ability to interact with others.
In Harrell’s case, the device is working with surprising accuracy and can even replicate his voice from the past.
The technology uses four implanted sensors in a region of the brain called the left precentral gyrus to interpret brain signals from 256 cortical electrodes when a user tries to speak. The signals are then converted into text, and a computer reads it aloud.
“We are recording from the part of the brain that’s trying to send these commands to the muscles,” said Sergey Stavisky, a co-leader of the study and a neuroscientist and faculty member at UC Davis Health. “We are basically listening into that, and we’re translating those patterns of brain activity into a phoneme—like a syllable or the unit of speech—and then the words they’re trying to say.”
In the past, BCI systems have been slow and prone to errors. But, researchers with BrainGate have worked to improve precision and speed. The field of BCI has now come a long way.
Even people who can no longer speak have been able to express themselves through BCI systems, highlighting just how impressive this technology truly is.
Harrell underwent 84 data collection sessions over the course of 32 weeks. In total, he used the BCI for 248 hours to verbally communicate in person and through video chat. The system read aloud in a voice that was synthesized from audio samples that were taken of Harrell before developing ALS.
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