Brain Implant Lets ALS Patient Speak via Decoded Thoughts
Science News reports Casey Harrell, who has ALS, used a BrainGate implant to speak at 56 words per minute over nearly two years, per a June 2026 paper.
The story in focus
Science News reports that Casey Harrell, an ALS patient, used a 256-electrode BrainGate 2 implant in his speech motor cortex to produce 183,060 sentences at 56 words per minute over nearly two years, per a June 2026 Nature Neuroscience paper. Researchers say the speech-decoding field remains early.
- Casey Harrell used the BrainGate 2 system for more than 3,800 hours at home with no researchers present, per a June 2026 Nature Neuroscience paper
- The system produced 183,060 sentences totaling 1,960,163 words at an average of 56 words per minute
- Harrell labeled 92 percent of sentences as decoded at least mostly correctly
- The implant uses 256 electrodes to decode 39 English phonemes, which machine-learning algorithms assemble into words
What the implant does
Casey Harrell, who has ALS, volunteered in July 2023 for the BrainGate 2 clinical trial. A UC Davis neurosurgeon placed four electrode arrays on the left side of his brain; together the arrays contain 256 electrodes that record electrical activity as he thinks about speaking.
Wires from pedestals on his head carry signals to nearby computers, where machine-learning algorithms match brain activity to 39 English phonemes and assemble those phonemes into words, sentences and paragraphs, says David Brandman, co-director of the UC Davis neuroprosthetics lab. The system lets Harrell type messages, send emails and have the words spoken aloud.
The reported results
The Science News episode reads figures from a Nature Neuroscience paper published in June 2026. Over nearly two years, Harrell used the BCI for more than 3,800 hours at home without researchers present, communicating 183,060 sentences and 1,960,163 words at an average of 56 words per minute. He labeled 92 percent of sentences as decoded at least mostly correctly.
Brandman told Science News that without the prosthesis, Harrell can say about six understandable words per minute. Harrell said the system, while slow and occasionally wrong, requires an internet connection and power, and an adapter emerges from the top of his head.
Early-stage context
Leigh Hochberg, director of the BrainGate Consortium and Clinical Trials, told Science News that speech decoding is at its very beginning and that only a small number of people worldwide have had an implantable BCI decoding speech. Harrell is described as the only person using such a system for communication this heavily.
According to the report, researchers petitioned the FDA to let Harrell's care partners connect and disconnect the system, allowing near-daily home use.
How many electrodes does Casey Harrell's BrainGate implant contain?
The implant contains 256 electrodes, arranged across four small arrays placed on the left side of his brain, according to Science News. The arrays record electrical activity as he intends to speak.
Sources & further reading
- How brain implants turn thoughts into speech ↗Science News
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