ALS patients type six words per minute using experimental brain-controlled cursor

Paralyzed person uses a brain-computer interface to type

Typing six words a minute may not sound like a lot, but for those people who are paralyzed and cannot type using conventional measures, it’s an accomplishment worth noting. This previously unthinkable feat was achieved by researchers at Stanford’s Neural Prosthetics Translational Lab who outfitted patients with a brain-computer interface (BCI) and taught them how to type up to six words per minute using a brain-controlled cursor, reports IEEE Spectrum.

The study, published in Nature Medicine, was designed to test an experimental neural system called BrainGate2, that is designed to literally turn thought into action. The system includes a 4x4mm sensor with 100 electrodes that is implanted into the brain’s motor cortex and records brain signals that are generated when a person either moves or thinks about moving a limb. These signals are sent to a decoder that turns this stimulus into a useful command for an external device, which is this experiment was a computer cursor.

Two quadriplegic patients with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, voluntarily underwent brain surgery to participate in this experiment. They gave of themselves for science and became “true partners with us in this endeavor,” said Stanford lead researcher Jaimie Henderson.

During the trials, the patients were asked to move a cursor on the computer screen to a specific target by thinking about moving their index fingers on a trackpad. Patients were able to hit their target in 25 seconds, a significant improvement over an earlier trial in which patients averaged 8.5 seconds per target.

In a second trial patients were asked to type words using the same brain control system that was now attached to Dasher, a computer accessibility tool that enables users to type without a keyboard by selecting letters on a screen. The app includes predictive typing that provides users with suggested letters to make it faster and easier to type full words. One of the participants, who had previous experience with the Dasher app, was able to type 115 words in 9 minutes, a pace of about six words per minute.

While six words per minute is quite a feat, Henderson believes this is only the beginning. He hopes to improve the system to the point where patients can fast type up to 40 words per minute. It’s not clear what hurdles the BrainGate2 implant will face as it seeks approval for use outside the lab, but Henderson is confident his system is “making very good progress” towards its goal.

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