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HomeminewsNew Tracing Approach to Restoring Vision Enables Patients to ‘See’

New Tracing Approach to Restoring Vision Enables Patients to ‘See’

Researchers at Baylor College of Medicine in Houston have proposed development of a device that would restore sight by bypassing damaged eyes and delivering visual information from a camera directly to the brain.

Publishing in the journal Cell, the researchers described their approach which stimulates implanted electrodes in a dynamic sequence, essentially ‘tracing’ shapes on the surface of the visual cortex. The approach was tested in four sighted and two blind people with existing implanted electrodes. It enabled them to recognise a variety of letter shapes without training and with high accuracy.

“When we used electrical stimulation to dynamically trace letters directly on patients’ brains, they were able to ‘see’ the intended letter shapes and could correctly identify different letters,” reported senior author Daniel Yoshor. “They described seeing glowing spots or lines forming the letters, like skywriting.”

They described seeing glowing spots or lines forming the letters, like skywriting

Previous attempts to stimulate the visual cortex have been less successful. Earlier methods treated each electrode like a pixel in a visual display, stimulating many of them at the same time. Participants could detect spots of light but found it hard to discern visual objects or forms. “Rather than trying to build shapes from multiple spots of light, we traced outlines,” says first author Michael Beauchamp. “Our inspiration for this was the idea of tracing a letter in the palm of someone’s hand.”

The investigators tested the approach in four sighted people who had electrodes implanted in their brains to monitor epilepsy and two blind people who had electrodes implanted over their visual cortex as part of a study of a visual cortical prosthetic device. Stimulation of multiple electrodes in sequences produced perceptions of shapes that subjects were able to correctly identify as specific letters.

The approach, the researchers say, demonstrates that it could be possible for blind people to regain the ability to detect and recognise visual forms by using technology that inputs visual information directly into the brain, should they wish to. However the noted that several obstacles must be overcome before this technology could be implemented in clinical practice.

“The primary visual cortex, where the electrodes were implanted, contains half a billion neurons. In this study we stimulated only a small fraction of these neurons with a handful of electrodes,” said Michael Beauchamp. “An important next step will be to work with neuroengineers to develop electrode arrays with thousands of electrodes, allowing us to stimulate more precisely. Together with new hardware, improved stimulation algorithms will help realise the dream of delivering useful visual information to blind people.”

The research was supported by the National Institutes of Health and published in Cell on 14 May 2020.