Brain-Computer Interface Restores Speech for ALS Patient Casey Harrell

Casey Harrell, 47, with ALS, has used an implanted BCI for two years to convert attempted speech signals into text and speech. The implant, placed in a speech-related cortical area, decodes neural activity in real-time, producing a digital voice mimicking his pre-ALS tone. He operates the system at home via eye-gaze navigation, enabling email, web browsing and full-time work.

ScienceAlert

The BCI is part of the BrainGate 2 pilot trial, a collaboration among UC Davis, Brown University and the Mass General Brigham Neuroscience Institute. The trial evaluates safety and feasibility for individuals with severe speech impairment and limited hand function in everyday settings.

ScienceAlert

Key contributors include participant Casey Harrell; neurosurgeon David Brandman, co-principal investigator; postdoctoral scholar Nicholas Card; neuroscientist Sergey Stavisky; and the institutions UC Davis Health, Brown University and Mass General Brigham Neuroscience Institute.

ScienceAlert

• Over 183,000 sentences (~2 million words) generated; average speed 56 wpm; accuracy ~92 % with a 125,000-word vocabulary.

People Magazine

• More than 3,800 hours of neural recordings across >400 days, the largest single-subject dataset with single-neuron resolution.

People Magazine

• The trial currently includes 26 participants.

ScienceAlert

UC Davis officials say the system lets people with severe paralysis communicate, work and interact digitally, and note the trial’s focus on safety and feasibility. Researchers say the dataset will guide future speech-decoding models. Brandman says the results cross a threshold for independent communication; Card emphasizes operation without researcher assistance.

People Magazine

The published results focus on Harrell’s experience; data from the other 25 participants remain unpublished, leaving broader efficacy unverified. Long-term safety, implant durability, and scalability to diverse populations are not addressed in the sources.

ScienceAlert

• “It is very sweet to have the ability to look at my wife’s eyes when she hears my voice and conjures up a sweet memory,” — Casey Harrell, BCI user.

People Magazine

• “Casey can use the system to communicate his own thoughts, not only while we're there in a controlled environment, but whenever he wants," says Nicholas Card, postdoctoral scholar, UC Davis Neuroprosthetics Lab "Sometimes, he would do that over 12 straight hours.” — Nicholas Card, postdoctoral scholar, UC Davis.

ScienceAlert

• “As far as we know, these 3,800 hours of brain recording as Casey used the system is by far the largest individual brain recording dataset with single neuron resolution,” — Sergey Stavisky, neuroscientist, UC Davis.

People Magazine

The BrainGate 2 trial continues to collect data from its 26 participants, refining decoding algorithms and privacy controls. Researchers plan to publish further findings, evaluate long-term outcomes, and explore broader clinical deployment pending regulatory review.

ScienceAlert