A Brain Implant Helped a Paralyzed Man Turn Thought Into Text

An illustration of a man with a brain plant imagining writing letters while a computer interprets those letters.
Nature 2021/Erika Woodrum

One of the best aspects of tech is how it enables people to accomplish tasks they may be incapable of otherwise. In intriguing new research, scientists developed a brain implant that let a man paralyzed from the neck down compose written text with just his thoughts.

Don’t expect too much going in because the technology is still early in the experimental stages. But with the proper brain implants, a man paralyzed from the neck down can write once again. He has to imagine the process of handwriting letters, and the brain implant picks up the neuro signals from that process. With enough training, it learns to interpret the signals as letters.

On the one hand, the speed is pretty remarkable. The 65-year-old participate (named T5 in the study) managed to achieve 90 characters per minute with 94.1 percent accuracy. That’s fairly comparable to typing text on a smartphone. Even more impressive, the method of visualizing letters topped previous “virtual keyboard” efforts by a wide margin. The latter techniques typically manage about 25 characters per minute, with a 75 percent accuracy.

On the other hand, it’s not all good news. Those fast results came with prepared sentences. When switching to free-form sentences, speeds dropped to 75 characters per minute, and accuracy dipped by 2 percent. And the whole system requires training for every user. After all, every person has different “handwriting” even in thought-form. Also, brain implants require brain surgery.

That involved implanting two brain chip implants, along with 200 electrodes, on T5’s premotor cortex. Scientists believe that area of the brain controls the intentions of movements and, thus, makes an ideal candidate for the process of capturing handwriting input. That seems to be true, based on the research. At least after testing one subject—more study on more subjects to reproduce the results is a logical next step.

Another large limitation is the alphabet researchers used. It didn’t include numerals, capital letters, or any grammar marks. That’s fine enough for basic text messaging style communication, but for anything longer, grammar is going to be a sore spot. So is the ability to write long numbers without spelling them out.

Still, if the results can be repeated, it’s the first step towards giving a viable form of communication to those who can’t speak for themselves. It could also restore the ability to write to someone who can speak but lost the ability to move a pencil or type on a keyboard. With time, and maybe some help from Elon Musk’s Neuralink, perhaps future versions can skip brain surgery and invasive brain implants. In which case, someday in the far future average people might write without a keyboard or pencil altogether. Or probably not. Only time will tell.

Josh Hendrickson Josh Hendrickson
Josh Hendrickson has worked in IT for nearly a decade, including four years spent repairing and servicing computers for Microsoft. He’s also a smarthome enthusiast who built his own smart mirror with just a frame, some electronics, a Raspberry Pi, and open-source code. Read Full Bio »

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