Blind people can ‘see’ letters traced directly onto their brains

Findings point to a way to bypass damaged eyes and deliver ‘sights’ directly to the brain

man standing at a screen drawing a letter with his fingers

After implanted electrodes stimulated this blind volunteer's visual cortex in a particular pattern, he was able to quickly perceive, and then write, the letter N.

M. Beauchamp et al/Cell 2020

Scientists have developed a new way to create “sights” for blind people. It’s like skywriting, but instead of blue sky, the letters are written on the brain itself.

The new approach, described May 14 in Cell, bypasses the eyes and delivers a sequence of electrical signals to the brain, creating the perception of a glowing light that traces a shape. With further refinements, the method might one day restore aspects of vision to people with damaged eyes or optic nerves. Scientists have been able to create artificial visions by manipulating the brains of mice, but advances for people have been slower (SN: 7/18/19).

Tiny jolts of electricity to the visual cortex, a span of neural tissue at the back of the brain, can make a person “see” small bursts of light called phosphenes. Previous attempts to restore vision involved creating multiple phosphenes at the same time, like light bulbs on movie marquees. But those signals were hard to interpret, forming smatterings of lights or a blob of coalesced lights.

A clearer signal comes from using electricity as a stylus, essentially tracing lines onto the visual cortex with electric current. In tests with six volunteers who had grids of electrodes implanted in their brains, researchers activated the electrodes in a sequence that traced the lines of alphabet letters. The process is akin to someone writing the letter N on someone’s palm by making an upward line, then a downward swoop and then moving back up again.

After electrodes in his brain “write” the shape of letters, a blind participant draws the corresponding shape that he perceives.

This sequential writing method allowed recipients to quickly perceive intended shapes, Michael Beauchamp of Baylor College of Medicine in Houston and his colleagues found.

Two participants were blind; four sighted participants had electrical grids implanted in their brains as part of treatment for epilepsy. One blind participant could recognize 86 shapes a minute with the technique.

So far, the researchers have tested only simple shapes, such as the letters C, W and U. But outlines of common objects, such as faces, houses or cars, could be traced using the same idea, the researchers write.

Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.

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