Brain implant is the first step toward returning sight to the sightless

In the majority of cases with people who lose their eyesight, the problem is caused by damage to their eyes or optic nerve, rather than the “seeing” part of the brain itself. That means that it might be possible to circumvent the eyes and instead direct information straight from a camera to the brain.

Researchers from Baylor College of Medicine in Houston recently made a big step toward this goal by way of a brain implant which allowed test subjects to visualize the shape of letters in order to identify them. In a study involving four sighted people with electrodes implanted in their brains for epilepsy monitoring and two blind people with electrodes implanted over their visual cortex, researchers demonstrated that it was possible to convey letters by using sequences of electrical stimulation.

“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,” senior author Daniel Yoshor said in a statement. “They described seeing glowing spots or lines forming the letters, like skywriting.”

In an abstract describing their work, the researchers write that, “We tested an alternative strategy in which shapes were traced on the surface of visual cortex by stimulating electrodes in dynamic sequence. In both sighted and blind participants, dynamic stimulation enabled accurate recognition of letter shapes predicted by the brain’s spatial map of the visual world. Forms were presented and recognized rapidly by blind participants, up to 86 forms per minute. These findings demonstrate that a brain prosthetic can produce coherent percepts of visual forms.”

The work demonstrates that it is indeed possible to convey visual information to blind people by inputting it directly into the brain. There’s still more work to be done before this can be used in clinical practice, however. In the study, the electrodes stimulated only a tiny fraction of the half billion neurons in the primary visual cortex. Creating more complex electrode arrays that are able to precisely stimulate larger numbers of electrodes will be an important next step. Nonetheless, this is incredibly promising work.

A paper describing the research was recently published in the journal Cell.

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