Cell . . . Significant developments are expected to help blind people regain their vision.

For more than 50 million blind people around the world, seeing light again is a distant dream.in order to interact with blind friends, we invented Braille, which uses a variety of raised character sets to express various meanings.but this recognition by finger touch is too inefficient.with the deepening of brain science research and the development of brain computer interface technology, scientists began to try to develop high-tech equipment that can let the blind see things: visual cortex visual prosthesis.on May 14, the international top journal Cell magazine published a black scientific and technological achievement. The research team led by Professor Daniel yoshor of Baylor Medical College in the United States, successfully presented the specified image in the brain of subjects by stimulating the cerebral cortex with dynamic current electrode.Professor Daniel yoshor said: "when we use electrical stimulation to track letters directly on the brain of patients, they can 'see' the expected shape of letters and recognize different letters correctly.they describe these letters as luminous spots or lines, just as normal people see letters in the sky."bypassing the eyes and directly implanting visual signals, we know that the reason why human beings can see, hear and touch the world around us is that our eyes, ears and skin transmit environmental stimulus signals to the cerebral cortex and generate neuronal activities in the corresponding areas of the cortex.it is the activities of these neurons that form our real perception of the external environment.of course, the cerebral cortex occasionally mistakenly forms some perception experiences that do not exist in the real world, such as auditory hallucinations and visual hallucinations.for the vast majority of blind people, blindness is mainly due to damage to the eyes or optic nerve, and the brain is no different from that of ordinary people.therefore, for decades, scientists have been trying to develop a device that can bypass the damaged eyes and optic nerve and directly transmit visual information to the brain, so that blind people can recover their vision.this device is called visual cortical prosthetic, also known as "bionic eye". It is an artificial organ that processes and encodes image information, stimulates the visual nervous system through the inserted microelectrode array, and makes the blind recover partial vision.as early as 1996, researchers from the University of Utah, a world-famous university in Utah, USA, successfully developed a visual cortex prosthesis. 100 needle electrodes with a length of 1.5 mm are arranged in a 10 × 10 square on a metal sheet with a thickness of 0.2 mm and an area of 12.96 mm2.in the experiment at that time, the researchers implanted electrodes into the patient's brain to stimulate the cerebral cortex, which successfully led to the patient's "optical illusion". The patient could describe the color predicted by the researcher, and rotate the eyeball with the position of the light spot.subsequently, the researchers improved the visual cortex prosthesis and developed a painless, non-invasive method of transcranial stimulation, which can make normal people and blind people produce "optical hallucinations", and can also be used to determine whether the visual cortex of patients is normal, and to help select suitable "bionic eye" transplant recipients.however, even with improvements, these visual cortical prostheses are still not very successful, because these methods only regard each electrode as a pixel in the visual display. By stimulating multiple electrodes at the same time, participants can "see" light spots to distinguish colors, but they cannot recognize useful information such as words and images.close your eyes, and letters appear in your mind. In order to make visual cortex prosthesis better help blind people understand the world, Professor Daniel yoshor started to develop dynamic activated electrodes.and the technical principle is also very interesting.when we were children, we should have played a simple version of the game "you draw and I guess". One partner wrote a word on the other's hand or other parts with his hand, and then asked another person to guess what the word was.obviously, if we directly press a Chinese character or letter on our hand, it is certainly difficult for another partner to guess the correct answer. This is also the limitation of visual cortical prosthesis before, which can not generate coherent stimulation, so that patients can have a coherent perception of letters or pictures.however, we can guess the answer more accurately by handwriting.this is also the inspiration of Professor Daniel yoshor, who uses dynamic electrodes to stimulate the cerebral cortex to draw the outline of letters or images, so that patients can more clearly identify the information researchers want to convey.in order to achieve this goal, the researchers improved the traditional electrode, combined with current steering and dynamic stimulation, and activated different electrodes in turn through precise current control to achieve the drawing of letters or picture outlines.to verify the feasibility of the improved device, the researchers implanted the electrodes into the visual cortex of four patients with visual impairment but not completely blind, and two patients with complete blindness, and then activated different electrodes in turn to draw the outline of the letter "Z". As a result, all six subjects "saw" the existence of the letter "Z".this video shows a blind subject, according to the dynamic stimulation to the visual cortex, to draw the image of letters in the brain. The results show that the blind can indeed regain the ability to recognize visual information by directly inputting visual information into the brain.however, the technology is not perfect at present, because the human visual cortex contains billions of neurons, and in this study, the researchers only stimulated a small part of them, only realized the transmission of letter information, which was not practical enough.in this regard, the first author of this paper, Michael S. Beauchamp He said that this study only proved that visual prosthesis in the visual cortex can really help blind people regain their "vision". Next, the research team will work with neural engineers to develop an array of electrodes with thousands of electrodes to improve the stimulation algorithm, so as to accurately stimulate every nerve in the visual cortex of the brain and help blind people "see" more complex information They see the dream of the world.speaking of this, people can't help thinking about it. They all say that hearing is false, but seeing is not necessarily believing.can the physical world felt by our brain through naked eye observation also be virtual? Reference: cell, Beauchamp et al.: "dynamic stiffness of visual cortex products form vision in sighted and blinded humans" writing to the mind's eye of the blind, cell (2020), - end-inature launched sister public iNews, focusing on the latest academic information reports, welcome to pay attention.scan or long press the QR code below to easily pay attention.