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A new implant for the blind connects directly to the brain

Researchers managed to do without the use of eyes, installing an implant in the brain that provides rudimentary vision




“Alli,” says Bernardeta Gomez in his native Spanish, pointing to a thick black line running along a white sheet of cardboard located at arm's length from her. "There".

Not a very impressive achievement for a 57-year-old woman - only Gomez is blind. And he has not seen for more than ten years. When she was 42 years old, toxic optical neuropathy destroyed the nerves connecting Gomez’s eyes to the brain, and she completely lost her sight. She cannot even recognize the light.

But after 16 years of darkness, Gomez was provided with a six-month window during which she could see a semblance of the world around her in very low resolution, represented by yellow-white dots and figures. This was made possible thanks to the modified glasses with a tiny camera. The device is connected to a computer that processes the picture in real time and turns it into electrical signals. A cable hanging from the ceiling connects the system to a connector built into the back of the head of Gomez, connected to an implant with 100 contacts, placed in the visual cortex of the back of her brain.


Bernarda Gomez in glasses with a camera. Unfortunately, the implant was already taken out of her brain - while this is a temporary device

With the help of the device, Gomez distinguished ceiling lamps, the simplest forms printed on paper and people. She even played a simple game like Pac-Man on a computer that he projected directly into her brain. Four days a week during the experiment, Gomez brought her sighted husband to the laboratory, where she was connected to the system.

The first moment of gaining vision Gomez at the end of 2018 was the culmination of decades of research conducted by Eduardo Fernandez, director of the neuroengineering department of the University. Miguel Hernandez in Elche, Spain. His goal is to restore vision to as many of the 36 million blind people around the world who would like to see again. Fernandez's approach is especially interesting because he does not use the eye and optic nerves.

Earlier research was conducted in attempts to restore vision by creating an artificial eye or retina. The approach worked, but in most of the blind, like Gomez, the nervous system that connects the retina to the back of the brain is damaged. An artificial eye will not solve the problem of their blindness. Therefore, in 2015, Second Sight, in 2011 in Europe, and in 2013 in the USA, which received permission to sell artificial retina for a rare disease, retinitis pigmentosa, switched the work of two decades from the retina to the cerebral cortex. Second Sight says the Argus II artificial retina is now used by a little over 350 people.

During my last visit to the palm-dotted city of Elcho, Fernandez told me that breakthroughs in implant technology and an improved understanding of the human visual system allow him to confidently switch to work directly with the brain. “Information in the nervous system is no different from information in an electronic device,” he says.

Restoring vision by sending signals directly to the brain is an ambitious task. However, its basic principles have been used in electronic medical implants in humans for decades. “Today,” Fernandez explains, “there are many electronic devices that interact with the human body. For example, pacemakers. If we talk about the senses, then we have cochlear implants . "


Eduardo Fernandez

The last device mentioned is the auditory version of the prosthesis created by Fernandez for Gomez: an external microphone and a processing system that transmits a digital signal to the implant located in the inner ear. The implant's electrodes send current pulses to nearby nerves, which the brain interprets as sound. The cochlear implant, first introduced to the patient in 1961, allows more than half a million people around the world to communicate normally in everyday mode.

“Our first patient was Berna, but over the past couple of years we have implanted five more blind people,” says Fernandez, a Gomez by name. “We did similar experiments on animals, but a cat or a monkey cannot explain what they see.”

And Berne is capable.

To participate in this experiment needed courage. To install the implant, a surgical operation was required on the body, which is generally healthy - and this is always a risk. And then it was necessary to remove it after six months, since the prosthesis was not approved for long-term wear.

Seizures and phosphenes


Before I see Gomez, I already hear her. She has a woman’s voice, ten years younger than her real age. The words in the speech are weighed, the voice is soft, the intonations are warm, confident and even.

Seeing her in the laboratory, I notice that Gomez got so familiar with the floor plan that she hardly needs help moving around the corridor and neighboring rooms. When I come to her to say hello, her face is first directed in the wrong direction until I say “hello” to her. When I give her a hand for greeting, her husband sends her brush to mine.

Today, Gomez came to an MRI of the brain to evaluate his condition six months after the removal of the implant (in the end, everything is fine). She also meets with a potential second patient who arrived there, who is also present during my visit. At some point, when Fernandez explains how the equipment connects to the skull, Gomez interrupts the discussion, bends over and presses the potential patient's hand to his nape, where there was a metal connector. Today, there is practically no port evidence. According to her, the surgery was so hassle-free that the very next day she arrived at the laboratory to connect and start the experiment. Since then, she has not had any problems or pains.

Gomez is lucky. The long history of experiments leading to its successful implantation has a mixed past. In 1929, German neurologist Otfried Förster discovered that he could cause a white point to appear in the patient’s field of vision by sticking an electrode into the visual cortex of the brain during surgery. He called this phenomenon phosphene . Scientists and authors of NF novels have since imagined the potential of prostheses connecting the camera and computer to the brain. Some researchers have even created rudimentary systems of this kind.

In the early 2000s, the hypothesis became a reality when an eccentric biomedical researcher, William Dobel, installed a similar prosthesis in the head of an experimental patient.

In 2002, writer Stephen Kotler watched in horror as Dobel raised his tension and the patient fell to the floor in a fit. It turned out that the brain does not like too strong stimulation with too much current. Dobel patients also had problems with infections. But at the same time, Dobel advertised his bulky device almost as ready for everyday use, supplementing the advertisement with a video in which a blind man slowly and uncertainly drives a car in a closed parking lot. After the death of Dobel in 2004, his prosthesis also left with him.

Unlike Dobel, who claimed to treat blindness, Fernandez constantly says things like “I don’t want to give you hope in vain” and “we hope that we will get a system that is suitable for use, but for now we are conducting early experiments.”

But Gomez was actually able to see.

Bed of nails


If the basic idea of ​​returning Gomez’s vision is quite simple - we connect the camera to the video cable leading to the brain - then its details are not at all simple. Fernandez and the team first had to deal with connecting the camera. What signal does the human retina emit? Trying to answer this question, Fernandez takes the retina from people who have recently died, connects it to the electrodes, shines on it and measures the current. His laboratory works closely with local hospitals, from where they can sometimes call at night, reporting the death of an organ donor. The human retina can be kept alive for no more than seven hours. His team also uses machine learning to match the electrical signals of the retina with simple visual images, which helps them write software that automatically simulates this process.

The next step is to take this signal and deliver it to the brain. In the prosthesis created by Fernandez for Gomez, the cable is connected to an implant of the well-known scheme , the “ Utah array ”, which is approximately the size of a small spot on the positive end of an AAA battery. From it sticks out 100 sharp electrodes a millimeter high - everything together looks like a bed of nails. Each electrode delivers current to several neurons, from one to four. When installing an implant, electrodes pierce the surface of the brain; when removed, 100 tiny drops of blood are formed in the holes.



Fernandez needed to calibrate the electrodes one at a time, sending signals to them with a gradually increasing voltage, until Gomez said where and when he saw the phosphene. Calibration of the entire hundred electrodes took more than a month.

“The advantage of our approach is that the electrodes of the array enter the brain and are close to the neurons,” says Fernandez. This allows the implant to provide vision using much lower currents compared to the Dobel system, which dramatically reduces the risk of seizures.

The big disadvantage of the prosthesis - and the main reason why Gomez was not allowed to walk with the prosthesis for more than six months - is that no one knows how long the electrodes can exist before either the implant or the user's brain begins to degrade. “The body’s immune system begins to break down the electrodes and surround them with scar tissue, which weakens the signal,” said Fernandez. There is also the problem of bending electrodes during human movements. Judging by experiments on animals and the early results of using the Gomez prosthesis, he suspects that the current scheme may last two to three years, possibly up to ten years, before failing. Fernandez hopes that small edits will help to stretch this period for several decades - which is critical for medical equipment requiring surgical intervention.

Ultimately, the prosthesis, like a cochlear implant, will need to transmit signals and energy wirelessly through the skull. But for now, for experiments, the prosthesis is connected via cable - this leaves more opportunities for updating equipment before stopping at a certain scheme of its operation.

With a resolution of 10x10 pixels, the maximum potential for the Gomez implant, one can distinguish between basic forms such as letters, a doorway or sidewalk. With the contours of the face and especially the details of the person’s face, it’s more and more complicated. Therefore, Fernandez supplemented his system with a pattern recognition program that determines the personality of a person and sends a pattern of phosphenes to the Gomez brain, which she learned to recognize.

On one slide of a technology presentation, Fernandez writes that “vision is possible” with a resolution of 25x25 pixels. And since in the current version the Utah array is so small and requires such little energy, Fernandez says that there are no technical limitations that would prevent his team from installing four or six implants from different sides of the brain, which would give vision with a resolution of 60x60 pixels or more. And yet, no one knows how much information coming in this way from such devices can be absorbed by the brain without overloads.

What does it look like



Fernandez and his graduate student with a prototype camera connected to a computer,

Gomez told me that if she had a choice, she would leave the implant, and would be the first in line for its updated version. When Fernandez has finished analyzing her array, Gomez plans to put it in a frame and hang it on the wall in the living room.

In the laboratory of Fernandez, he offers me to connect to a non-invasive device that he uses to study patients.

Sitting in the same leather chair that Gomez was in last year during a breakthrough experiment, I feel how a neuroscientist is pressing a wand with two rings to my head on one side. This device, a “butterfly coil,” is connected to a box that excites neurons in the brain using powerful electromagnetic pulses. This phenomenon is calledtranscranial magnetic stimulation . The first impulse is like an electric shock to a scalp. Fingers involuntarily dig into the palm. “Look, it works!” - chuckles Gomez. “This is your motor cortex. Now let's try to call you phosphenes. "

The neurobiologist changes the position of the wand and adjusts the machine to rapidly repeating pulses. This time, after starting, I feel tingling in the back of my head, as if someone was using my skull as a door knocker. Then, although my eyes are open, I see something strange: a bright horizontal line flickering in the center of my field of vision, as well as two luminous triangles filled with something like an image on a TV in the absence of a signal. The image disappears as quickly as it appeared, leaving behind a slight afterglow.

“About the same thing Bern can see,” says Fernandez. Only her “view” of the world remains more stable as long as a signal enters the brain. She could also turn her head and use glasses to look around the room. I saw only the internal phantoms of the brain, stimulated by electricity. Gomez was able to reach out and touch the world she was looking at for the first time in 16 years.

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