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Brian Bussard, a 56-year-old American who lost his eyesight, now has 25 microchips in his brain. These brain-implanted devices, which aim to provide "artificial vision", are the result of decades of exploration and an attempt by scientists to test the efficacy and safety of such chips, and they were placed in the brains of the project's first volunteer, Basad, in February 2022.
Basad lost sight in his left eye at the age of 17 due to retinal detachment, and lost vision in his right eye in 2016. Life without light is extremely difficult, but it is also a daily routine that every visually impaired person has to adapt to.
In 2021, he heard that the Illinois Institute of Technology in Chicago was conducting a trial of visual prosthesis and was intrigued and signed up, but the researchers also reminded him that the device was experimental and that participants should not expect to return to normal vision levels.
Eventually, the chip in his brain succeeded in giving Basad artificial vision, but it was very limited – what he described as "a point of light on a radar screen". With the implants, he is able to perceive people and objects in white and rainbow dots.
A team of experts from the University of Miguel Hernández in Spain has so far implanted a similar system in four visually impaired people.
Industry is also making great efforts to explore this area. Cortigent, a California-based medical device manufacturing company, is developing an artificial vision device called Orion that delivers images directly to the user's brain through implants and glasses, and six volunteers have tried the product. Neuralink, a neurotechnology company founded by Elon Musk, is also working on brain implants for artificial vision. In March of this year, Musk posted on social media X that Neuralink's device, Blindsight, "already works on monkeys...... "at first the resolution is low, just like the early Nintendo graphics cards, but it may eventually surpass the average person's eyesight." ”
Considering the extreme complexity of the visual formation process, Musk's prediction is unrealistic. Improving a person's vision through brain implants requires overcoming huge technical hurdles. Of course, for the blind community, even basic vision is a huge change.
"Mobile phone network in the brain"
Philip Troyk, a professor of biomedical engineering at the Illinois Institute of Technology, led the pilot project in which Bassard participated. "The current work in this area is not aimed at restoring biological vision, but at exploring the possibilities of artificial vision," he said. ”
When light hits the eye, it first passes through the cornea and lens, the outer and middle layers of the eye. When light reaches the back of the eye (retina), cells there (called photoreceptors) convert it into electrical signals. These electrical signals travel through the optic nerve to the brain, which translates these signals into images. Without an intact retina or optic nerve, the eye cannot communicate with the brain, a condition that many people who are completely blind face.
The devices built by the Troic team and Neuralink can completely bypass the eye and optic nerve and send messages directly to the brain, which is why they have the potential to overcome blindness from any cause, whether it's an eye disease or trauma.
The visual cortex processes the information sent by the eyes and is located at the back of the brain, making it easy to implant a device. To place 25 chips into Basad's brain, surgeons performed a routine craniotomy and removed a piece of the skull.
The chip implanted in the brain is actually a tiny stimulator that emits a weak current, is about the size of an eraser and contains 16 tiny electrodes, each thinner than a human hair, each individually controlled. A total of 400 electrodes were implanted in Barsad. In Troyck's words: "It's like having a cell phone network in your brain." ”
There are no points of light
With a camera on a special glass, the device captures an image of its surroundings and converts it into commands that speak to the chip's network with the help of software processing, which turns on electrodes to stimulate neurons. This stimulus produces a visual perception called "phosphenes". It looks like a point of light, but in reality the eye does not receive light.
Because the stimulator is concentrated in one part of the visual cortex, Basard can only see light illusions in the lower left part of the visual field, but this is enough to improve his ability to navigate the room and perform basic tasks, such as selecting the plate he wants from four different objects on the table.
How to produce better images? This is the most important concern for the developers of visual prostheses. Dr. Xing Chen, assistant professor of ophthalmology at the University of Pittsburgh, said: "The more electrodes, the more optical illusions can theoretically be generated, and the more complex and delicate the shape under artificial vision. ”
In 2023, Dr. Chen and his colleagues published a paper describing their work on creating a visual prosthesis with 1,024 electrodes: they tested the visual prosthesis system on experimental monkeys and found that the monkeys actually recognized letters with the help of the device. The team estimates that hundreds to thousands of electrodes would be needed to restore vision to blind people in this way.
But Troic argues that the key is not the number of electrodes, but the location of the electrodes, which are distributed in the visual cortex to produce more points of light in a larger field of view, at the cost of more invasive surgery.
Customized stimuli
The Miguel Hernández University team only allowed volunteers to receive one implanted device containing 100 electrodes. However, according to their paper published in 2021, a 60-year-old visually impaired woman was able to recognize lines, shapes and simple letters, even with a small number of electrodes. Eduardo Fernández, a neuroscientist who led the project, said three more blind volunteers had similar improvements in vision.
Fernández stresses that artificial vision "is not seeing again" and that its main goal is to improve the orientation and mobility of blind people. In one test, a man with a visual prosthesis was able to avoid obstacles while walking on a virtual reality treadmill. Fernandez hopes to increase the number of implanted electrodes in the future, so that the visually impaired can have more optical illusions and perceive richer and more detailed images.
Fernández's team is currently working on four of the earliest volunteers – each with a slightly different visual cortex, so they had to experiment with where the implanted electrodes were and how much electrical stimulation would be delivered.
We tailor the stimulus to each volunteer. ”
Customizing implants to get the best results can be challenging. In early experiments, scientists used large electrodes placed on the surface of the brain to produce light hallucinations at relatively high electrical currents, a stimulus that sometimes causes seizures, pain, and damage to brain tissue. Dr Chan pointed out that it is not easy to achieve both strong enough electrical current to produce optical illusions and avoid unnecessary side effects.
Flexible electrodes and mobile devices
The longevity of the implant is also quite critical. Both Chen's and Hernandez's teams used a rigid implant called the Utah array, a square grid of 100 tiny silicon needles, each with an electrode at the tip. The Utah array can last for months to years, but it stops working when scar tissue forms around the implant and interferes with its ability to receive signals from nearby neurons. The implant from the Illinois Institute of Technology team is made of iridium oxide and looks like a miniature bristled brush head.
New implants from companies such as Neuralink have smaller, flexible electrodes that can penetrate the brain. For example, Neuralink's coin-shaped device is inserted into the skull with thin, wire-like electrodes that extend into the brain tissue.
Dr Chan pointed out that softer electrodes may make implants last longer, but it remains to be seen how long they will work in the brain.
As mentioned earlier, the first volunteer recruited by the Illinois Institute of Technology team, Basad, underwent surgery six years after being completely blind, and Miguel Hernandez University implanted a participant who had been blind for 16 years and was still able to see objects vaguely.
Dr. Chan noted:
Years after blindness, the visual system begins to deteriorate, and the sooner you intervene, the better, although this has yet to be systematically studied and proven. ”
At an event in November 2022, Musk claimed: "We believe that even people who are born blind who have never had vision can regain their sight." Fernández is skeptical and points out that there have never been attempts to restore vision to people who are born blind, and that in theory, a functioning visual cortex is required to obtain artificial vision, but that people who are born blind have never used this part to process visual information.
At this stage, Basad can only use visual prostheses in the laboratory – the technical team is responsible for controlling the stimulus. Troic and colleagues are developing a mobile system that will allow participants to use the device at home in the future. In addition, Troic is also looking for more volunteers who will be blind as adults.
Sources:
The Next Frontier for Brain Implants Is Artificial Vision
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