A brain implant helps a blind woman see shapes

The microimplant may allow blind people to regain their basic vision in the future. Initial tests on a Spaniard, who had been blind for 16 years, showed promising results. The woman, who was 57 at the time of the tests, wore special glasses with a camera that sent her data to an implant in the visual cortex of the person. The electrodes in her brain then stimulated neurons in such a way that she had the impression that she could see light. This allowed the subject to recognize shapes and even play a simple video game.

In order for us to see something, our eyes and brain must work together: the receptors in our eyes pick up light stimuli, convert them into electrical nerve signals, and send them through the optic nerve to neurons in our brain’s visual cortex. There, the signals are processed and combined into an image. If the eyes, visual cortex, or the nerve connections between them are damaged, we don’t see anymore – at least so far.

signals directly in the brain

A study by scientists led by Eduardo Fernández of the Miguel Hernández University in Spain now gives hope that blind people could regain at least some of their eyesight in the future thanks to technical assistance. For this purpose, scientists have developed a tiny implant that is able to stimulate neurons in the visual cortex. The signals do not come from the eyes, but from a small camera attached to special glasses.

The tester of this artificial vision system was the 57-year-old Spanish Bernardet Gómes during the tests. 16 years earlier, she lost her eyesight completely after toxic substances destroyed her optic nerves. Although the signals from her eyes no longer reached her brain, she sometimes saw so-called phosphenes – light phenomena that are not caused by actual light, but by other stimulation. We can achieve a similar effect by closing our eyes and gently pressing the eyeballs. Such phosphenes are not uncommon in blind people. Fernández and his colleagues used this phenomenon in their prosthetic vision.

Shapes made of points of light

To allow Gomez to regain basic vision, the researchers implanted a 3.6 by 3.6 millimeter chip with electrodes in her brain’s visual cortex. This chip was able to both record and stimulate the electrical activity of neurons – and use this stimulation to trigger phosphenes in a targeted manner. Depending on how and where exactly the electrodes sent their signals, Gomez perceived different points of light. After about two months of daily training, she was able to distinguish these intentionally generated phosphens from spontaneous ones – and see how they formed into shapes. The stimulation thus followed the images recorded by the camera on special glasses, albeit in a rudimentary form, in their brain.

In this way, Gómez was able to recognize letters, shapes and color boundaries and even play a simple video game. According to the scientists, the first results of this experiment show that the implant is also safe for a long time. “We found no evidence of neuronal irritation or seizure induction, and the subject reported no adverse side effects of electrical stimulation,” the researchers said. The implantation was also smooth and the electrodes functioned unchanged throughout the six month study period. Similar implants that allow amputees to control artificial limbs have proven to be safe for years.

New opportunities for the blind

“These results are very exciting as they show both safety and effectiveness,” said Fernández. “We have taken a significant step forward and demonstrated the potential of this type of device in restoring functional vision to people who have lost their eyesight.” In further research, the team hopes to work on improving the spatial resolution of the images produced and tested. system with more entities and for a longer period of time. “One of the goals of this research is to improve the mobility of blind people,” says co-author Richard Normann of the University of Utah in Salt Lake City. “This would make it easier for them to recognize people, doors or cars. This can increase independence and security. This is what we are striving for.

Source: Eduardo Fernández (Miguel Hernández University, Elche, Spain) et al., Journal of Clinical Investigation, doi: 10.1172 / JCI151331

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