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Paralyzed Man Writes, Using Only Imagination — and an Algorithm

With implanted electrodes, the volunteer, 65, achieved 90 characters per minute

The science media has been abuzz these last few days with news of man paralyzed from the neck down who was able to type using only his thoughts — communicating via a brain implant:

A 65-year-old man had two grids of tiny electrodes implanted on the surface of his brain. The electrodes read electrical activity in the part of the brain that controls hand and finger movements. Although the man was paralyzed from the neck down, he imagined writing letters softly with his hand. With an algorithm, researchers then figured out the neural patterns that went with each imagined letter and transformed those patterns into text on a screen.

Anushree Dave, “Brain implants turn imagined handwriting into text on a screen” at ScienceNews (May 12, 2021)

The abstract of the paper at Nature reveals that “our study participant, whose hand was paralysed from spinal cord injury, achieved typing speeds of 90 characters per minute with 94.1% raw accuracy online, and greater than 99% accuracy offline with a general-purpose autocorrect. To our knowledge, these typing speeds exceed those reported for any other BCI, and are comparable to typical smartphone typing speeds of individuals in the age group of our participant (115 characters per minute).” Here’s the article.

This was the fastest communication yet seen in brain-computer interfaces (BCI). Researchers hope that, with further improvements, BCI can aid in stroke recovery, especially in speech recovery. Speech, they say, is faster than handwriting and something of a mystery:

The rate of speech is about 150–200 words per minute, Henderson notes, and decoding it is an interesting scientific endeavor because it’s uniquely human and because it’s not fully understood how speech is produced in the brain. “We feel like that’s a very rich area of exploration, and so one of our big goals over the next five to ten years is to really tackle the problem of understanding speech and decoding it into both text and spoken word.”

Shawna Williams, “Brain-Computer Interface User Types 90 Characters Per Minute with Mind” at The Scientist (May 13, 2021)

What makes the technology possible is that neurons can interact with manufactured electrical signals:

The study participant 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 patient’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.

Bret Stetka , “New Brain Implant Turns Visualized Letters into Text” at Scientific American (May 12, 2021)

There are also fruitful research programs aimed at restoring movement and controlling prostheses by thoughts as well.

While all these developments are still a long way from our local rehab clinics, they are promising proofs of concept. The mind can control the injured body or communicate with the world again, if only it can reconnect.

You may also wish to read:

Why robots offers hope for paraplegics The breakthrough idea is that the human brain can process electronic signals from machines as well as signals from peripheral nerves. Cheng’s team’s goal is real-time measurement of brain responses to enable robotic exoskeletons to adapt seamlessly to the needs of individual paraplegics.

Prosthetic hand controlled by thoughts alone? It’s here. Decades ago, no one could control a prosthesis only by thought. And there is lots of room for the field to grow still.


High tech can help the blind see and amputees feel. It’s not a miracle; the human nervous system can work with electronic information.

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Paralyzed Man Writes, Using Only Imagination — and an Algorithm