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A new brain implant lets paralysed people write with their minds

By Alma Fabiani

May 15, 2021


For decades now, scientists have been connecting the impulses our brain generates whenever we do something—be that moving, speaking or simply sensing—not only to understand and treat brain diseases but also to help people with disabilities. Using Brain-computer interfaces (BCIs), researchers have been aiming to restore movement in people with paralysis and potentially help treat neurological and psychiatric diseases. And it certainly looks like they’re getting somewhere.

A study conducted by a team at Stanford University and published in Nature reports on a brain implant that will allow people with impaired limb movement to communicate with text formulated in their mind, no hands needed. How does it work exactly?

When coupled with electrodes implanted in the brain, the artificial intelligence software was able to ‘read’ the thoughts of a man with full-body paralysis as he was asked to convert them to handwriting. The BCI transformed his imagined letters and words into text that appeared on a computer screen—a form of “mental handwriting,” as Scientific American calls it.

The technology could benefit millions of people worldwide who are unable to type or speak because of impaired limbs or vocal muscles. Until now, co-senior study author Krishna Shenoy had helped analyse the neural patterns associated with speech. In other words, Shenoy had managed to decode imagined arm movements so that people with paralysis could move a cursor on a keyboard screen in order to type out letters. However, this specific technique only allowed participants to type around 40 characters per minute, far lower than the average keyboard typing speed of around 190 to 200 characters per minute.

With the help of his team, Shenoy’s recent work focused on imagined handwriting as a way to improve the speed of communication for the first time, which the researchers hope it will reach, at very least, smartphone texting rates. Their technique allowed the study subject, who was 65 years old at the time of the research, to mentally type 90 characters per minute. Although we’re not at the 190 characters per minute efficiency just yet, that rate is not far from average for most senior texters “who can typically type around 115 characters per minute on a smartphone,” according to Scientific American.

The study participant had suffered a spinal cord injury in 2007, and had lost most movement below his neck. In 2016, Stanford neurosurgeon Jaimie Henderson, co-senior author of the paper, implanted two small BCI chips into the man’s brain. Each of the chips had 100 electrodes capable of sensing neuronal activity. They were implanted in a region of the motor cortex that controls movement of the arms and hands, allowing the researchers to profile brain-activity patterns associated with written language.

Not only could this technology’s recent success help restore communication in people who are severely paralysed, but it could also light the way for more progress in intracortical brain-computer interfaces. But as assistant professor of neurology at Thomas Jefferson University Mijail D. Serruya, who studies BCIs in stroke recovery but was not involved in the research, told Scientific American, “Why not teach the person a new language based on simpler elementary gestures, similar to stenography chords or sign language?”

Through his question, Serruya highlighted the fact that focusing on restoring communication via written letters may not be the most efficient means of doing so. In fact, although translating the brain’s control over handwriting is a significant first step in reclaiming someone’s ability to communicate, decoding what that person actually intends to say is still a major challenge researchers face.

For now, given that we generate speech much more quickly than we write or type, it’s hard to predict when the researchers’ method will be translated into a real device that anyone can buy. “We hope it’s within years and not decades!” said Frank Willett, lead author of the paper and a research scientist at Stanford’s Neural Prosthetics Translational Laboratory. Meanwhile, Elon Musk has made a monkey play Pong telepathically. Priorities, am I right?