We have already written how scientists have learned to "reprogram" retinal neurons, which helped to regenerate its tissues. But the new discoveries do not end there. Scientists from the Netherlands Institute of Neuroscience implanted 1,024 electrode plates into the visual cortex of monkeys. Later, thanks to brain microstimulation, they made them recognize letters on a blank screen. The knowledge gained will help improve the resolution of restored functional and useful vision in the future.
Blindness affects 40 million people worldwide. Scientists believe that one day neuroprostheses will help restore functional vision to blind people. The idea of stimulating the brain with implants to restore vision to blind people dates back to the 1970s. How real is it? Blindness is usually the result of damage to the optic nerve or retina, and its recovery is directly related to the brain. Scientists are testing various methods for correcting vision. And if the visual cortex is not damaged, then its point stimulation can partially restore vision. In this case, the eye becomes able to see simple shapes, points of light or phosphenes . So, in November, using this method, it was possiblemake visually impaired people see certain letters so that they could even draw them.
Electrical stimulation of the visual cortex as a method of restoring vision has been used for a long time. But the technology requires certain conditions and is quite limited. The tissue-safe amperage is relatively low - only a few milliamps. Therefore, usually a small number of surface electrodes are used, which activate a small area of the cortex. Dutch biologists decided to delve deeper and test a new approach.
The experiment helped to make sure that stimulation of the visual cortex is still effective for partial restoration of vision. In addition, tests have shown that increasing the current during stimulation improves the bottom line and is relatively safe for the monkey brain.
For testing, the monkeys were implanted with new implants, consisting of 1024 electrodes. The monkeys learned to recognize simple patterns. The implant interacted directly with the brain, bypassing the visual processing centers - the eyes. Among the disadvantages - the method is applicable only for those who have lost their sight as a result of trauma or after damage to the optic nerve, it will not help the blind from birth.
How did the experiment go?
To carry out the tests, the scientists used two experimental monkeys L and A. To begin with, they were taught to recognize 16 letters. The macaques were observed during the learning process, the movements of their pupils on the computer screen were recorded with a gaze tracker.
In the first stage, by stimulating the primary visual cortex, macaques were made to see two phosphenes on opposite sides of the screen. What was happening was watched with the help of an eye tracker: if the eye went in the right direction, it was believed that the monkey sees a recreated visual image.
The power of stimulation was reflected in the accuracy of perception:
- ~ 12.6 milliamperes - the test subjects saw at least half of the images;
- 23 milliamperes - it took the L macaque to fully recognize phosphenes;
- 50 milliamperes - Required by macaque A for 100% phosphene recognition.
At the next stage, we observed how monkeys perceive letters with similar methods of exposure. Only now they did not act pointwise, but the microelectrodes recreated the image of the letters. Macaque L was able to understand 80% of the letters, the second A - 71%. When switching to the visual version, these experiments improved by 13% and 17%, respectively.
Buyable vision is the second way
Dutch company Envision has adapted Google Glass, turning it into a device suitable for visually impaired and blind people. The glasses help to navigate in space, describe the environment and recognize people whose photos are in the phone's phonebook along with a photo.
Previously, the company developed an application with similar functionality: it recognizes surrounding objects, text and people. Therefore, the collaboration with Google Glass came out prepared.
A camera is built into the glasses, it reads information from the surrounding world. Interaction with the user takes place through a voice assistant that reproduces all the necessary information. Points are available to order. The starting price of the device, including fees, is $ 3268.
