Bernardeta Gómez was a professor of Biology at a high school in Valencia when, 16 years ago, septicemia left her blind. Now 57, an implant inside the brain has allowed him to perceive patterns and recognize some letters of the alphabet. You have even been able to play a simple version of the beginnings. The system, designed by scientists from the Miguel Hernández University of Elche (UMH), had a hundred electrodes placed in the brain region responsible for vision. It is the first time that this technology has been used in a blind person. The old teacher’s blindness returned once she unplugged, but now they are recruiting new volunteers to go further.
“They put the implant on me on Monday, October 22, 2018. On Tuesday we were already doing the experiment,” recalls Gómez. “The first three months, what was going to last the investigation, we did not advance much, but I insisted that it be extended. It was then that I began to distinguish changes in intensity. They were like very luminous sequins and, depending on the parameters, I saw them more or less intense, more or less large ”, he adds.
What Gómez calls “sequins” are the so-called phosphenes, a visual phenomenon in the form of flashes or bright spots. Anyone who rubs their eyelids with any force can see a shower of them with their eyes closed. In blind people they are common and often spontaneous. In the case of the former teacher, she used to see them when there was a loud sound or she had a start, but also unexpectedly.
The director of Biomedical Neuroengineering Group of the Bioengineering Institute of the UMH Eduardo Fernández explains that phosphenes appear as a specific point in visual space. “The retina has a kind of map in the cerebral cortex that connects with the visual field. This retinotopic map had been studied in people who see: you stimulate a certain part and you see something specific and not something else. We have been surprised that these predictions are completely fulfilled in a blind person. The map is still there ”, he details. The problem they encountered with the teacher is that sometimes they appeared by stimulating the right occipital cortex (behind the ear, in the upper part), the seat of visual processing, and sometimes they did so spontaneously. As Gomez jokes, “they [por los científicos] they were as blind as I was ”.
The research, in which scientists from the Alicante university, the Netherlands Institute of Neuroscience, or the University of Utah (United States) have participated, is pioneering in many ways. What they did was insert a 96-electrode plate into the brain. Each is 1.5 millimeters long and 80 microns in diameter. “They are the size of the neurons with which we want to communicate,” says Fernández. Neuroscientists have been testing these plates for several years in people who are paralyzed or unable to communicate. “It is the first time that it has been implanted in the visual region of the brain and in a blind person,” highlights the UMH researcher. In addition, the electrodes not only send electrical signals, they also pick up the neuronal response, sending it to an external system. Something just as new. All the details of the study appear in the latest edition of the scientific journal Journal of Clinical Investigation.
The system was completed with an artificial retina (an image processor similar to that of cameras, mounted on conventional glasses). His mission was to convert the optical stimulus into electrical, which is what activates the brain. Unlike other approaches that try to get the eye to regain part of its vision, such as optogenetics, “here we have missed the eye,” says the project manager. Gomez’s eyes didn’t even see the light.
“I’m seeing a point … they were complicating it and I began to see narrow, wide, square bars … and then I learned to distinguish the patterns, I came to perceive a human face and that of a dog”,
Bernardeta Gómez, former teacher and blind for 16 years
At first, the researchers activated the electrodes one by one. So they caused the appearance of a single phosphene. The Biology teacher remembers saying: “I’m seeing a point.” As Gomez’s brain trained, the study authors increased the complexity of the stimulation, increasing the number of electrodes they activated at the same time. “They made it more complicated and I began to see narrow, wide, square bars … and then I learned to distinguish the patterns, I came to perceive a human face and that of a dog,” he says. He was even able to play a simplified version of the beginnings where she had to avoid getting caught. “It was an experience, how to say, total. I can’t get the words out, ”he ends.
In detecting patterns and shapes, the patient went from a success rate of 81.4% to 100%. In the last month of the six that the experiments lasted, they went further and investigated the perception of letters using the activation of 16 electrodes simultaneously. Gómez was able to distinguish some, such as L, C, V or O with 70% correct answers. But they could not induce the perception of the entire alphabet and they do not know why.
Almost everything in the research is so new that there were no precedents to compare with. For example, they adjusted the electrical signal until they identified the threshold necessary to achieve a response from the teacher’s brain. Attempts to stimulate the brain so that blind people regain at least part of their vision date back to the 1970s. But it was always a stimulation from outside. Here they open the head and go directly to the brain. Unlike scalp electrode systems, which operate in the milliamp range, these direct implants lower amperage by several orders of magnitude. Closeness allows for higher resolution with less energy, but had to be tuned to avoid overstimulation. The average threshold of the former teacher was estimated at 66.8 microamps.
For Jaume Català, ophthalmologist at the Catalan hospitals Sant Joan de Déu and Bellvitge, the results of this research are “a milestone in artificial vision with cortical stimulation”. He quickly limits his enthusiasm: “This is an individual case and a pilot study.” For Català, “this approach is capable of proposing possible solutions in those patients who at some point had vision and have lost it completely, either due to alterations of the retina or the optic nerve”. But, he clarifies, the visual cortex must be functional. “We are still far from achieving a functional vision both due to the duration of the implants, as well as their predictability and the need to study and better understand the complexity and multiple pathways of the visual areas of the cortical region”, he recalls.
“We have received requests from all over the world hoping to see again, but that will not happen, this is research”
Eduardo Fernández, Institute of Bioengineering of the Miguel Hernandez University
The work also shows how much remains to be done. In order for people like Gómez to take advantage of the results of research of this type, several problems still need to be solved. One is the number of electrodes. The 96 used here, which occupy a square of 4×4 millimeters, would have to be enlarged a lot. Fernández’s team published in the magazine Science an experiment in which they used a plate with 1,024 electrodes to study brain response, “But it was in monkeys that they saw,” recalls the neuroscientist.
Another obstacle to avoid is that Gómez had to be connected to a central unit while participating in the tests. Once it was done, it would unplug it and stop seeing those phosphenes. And transmitting and receiving wirelessly would require power that could lead to other problems. “We need more data” says the UMH researcher. To do this, they have extended the trials to other people. “We have received requests from all over the world hoping to see again, but that is not going to happen, this is research. We are looking for people like Berna, who I knew I would never see again. If not, we could do a lot of harm to them ”, he highlights.
Bernardeta Gómez assures that she does not feel special nostalgia for having returned to see a little for a few months. In his own words: “I knew what I was going for. I was very clear that I was not going to regain my sight, but I feel great personal satisfaction and with that I already feel paid ”.