Bernardeta G?mez, speaking in a local Spanish accent, speaks “All? ( ” Spanish ” ” ” ” ” ” ” ” ” ” ” ” Spanish” ( ” ” ” ” Spanish” ) while pointing to a black line on the whiteboard in front of him. For a 57-year-old woman, there’s nothing to show off when she can see a black line painted on a whiteboard.
Gomez’s brain’s electrical signal, each of which represents an electrode, with curved lines in the grid showing signals from neurons
But for Gomez, who has been blind for 16 years, it’s remarkable. At the age of 42, optic neuropathy destroyed the nerves that connect Gomez’s eyes and brain, and she was completely blind edified and could not even feel a touch of light.
Sixteen years later, Gomez was given a chance to see the world around her for six months, though all she saw was yellow-and-white dots and patterns.
To bring Gomez back to light was a pair of glasses with a miniature camera, which was processed by a computer and converted into an electrical signal. A cable hanging from the roof passes the signal through a port implanted into the skull and transmits it to 100 electrodes implanted in Gomez’s visual cortex.
Gomez wears glasses with a camera.
With this system, Gomez can see ceiling lights, people and letters printed on paper, basic graphics, and she can even play a simple Bean Eater game.
Gomez is back in the dark for the first time in late 2018, the result of decades of research by Eduardo Fernandez, head of the department of neuroengineering at Miguel Hernandez University in Elche, Spain.
Fernandez has set himself a goal: to restore vision to as many blind people as possible around the world. Data show that the number of blind people worldwide reached 36 million. Fernandez’s method is exciting because it bypasses the eyes and optic nerves.
In early studies that brought blind patients back to light, most attempted to help them restore vision through artificial eyes or retinas. These studies have also been somewhat successful.
But the vast majority of blind patients, represented by Gomez, are damaged by nerves that connect the retina and the visual cortex, and artificial eyes are not enough to make them see the light again. That’s why Second Sight abandoned its 20-year effort in 2015 to shift the focus from the retina to the visual cortex.
Second Sight was approved in 2011 and 2013 to sell an artificial retina in Europe and the United States. Second Sight says more than 350 people are using their Argus II artificial retina.
During my most recent visit to Elche, Fernandez told me that advances in implantation, a more precise understanding of human vision systems, gave him the confidence to see the light again by operating directly through the brain. Information in the nervous system is no different from information in electronic devices.”
It may sound bold to see blind people again by transmitting signals directly to the brain, but mainstream medical devices have been using their rationale for decades. “Now, a lot of electronic devices interact with the human body, and pacemakers are one of them, and one of the sensor systems is a cochlear implant,” Fernandez explains. “
Fernandez implanted an artificial vision system for Gomez
Cochlear implants consist of two main parts: the processing system processes the signals generated by external microphones and transmits digital signals to the implants in the inner ear, the electrodes of the implants transmit electrical currents to nearby nerves, and the brain processes the signals coming from the nerves, which can be heard by patients with hearing impairments.
Cochlear implants were first used to help hearing-impaired people hear sounds in 1961, and more than half a million people worldwide now use cochlear implants.
“Gomez is our first patient, but in the next few years we will have five blind patients implanted in this system,” Fernandez said. We did similar experiments in animals, and cats or monkeys can’t tell us what they see. “
But Gomez can.
Gomez needed a lot of courage as an experimenter. She needs to have an implanted electrode through brain surgery and take it out six months later (because the technology has not yet been approved by regulators), and she could be more vulnerable if something goes wrong.
Spasms and photovisions
Gomez was lucky. Before her, similar experiments were tortuous.
As early as 1929, a German neurologist named Otfrid Foerster discovered during an operation that an electrode was inserted into the patient’s visual cortex and the patient would see a white dot.
Since then, scientists and sci-fi authors have opened up holes in the brain, envisioning a variety of artificial vision systems: signal transmission routes for the camera-computer-brain. Some researchers have even developed preliminary systems.
In the early 2000s, this hypothesis became a reality when a biomedical researcher named William Dobelle installed an artificial vision system on the head of a patient who had volunteered for the trial.
Unfortunately, shortly after Dobelli turned on the system, the patient had cramps and fell to the ground. The reason for the inlaters is that the current is too high and the stimulation of the brain is too strong beyond the normal range. The patient was also infected.
But Dobelli claims his system is close to everyday use and has released a video of a blind patient driving slowly in a closed parking lot. Dobelli died in 2004 and his artificial vision system disappeared.
Fernandez is much more conservative than Dobelli, who almost always says, “We want to develop artificial vision systems that can be used by people, but at the moment we’re just experimenting early.” “
But Gomez did see the light again.
If the principle behind Gomez’s ability to restore vision – transmitting video signals from the camera to the brain – is simple, but the details are much more complex.
Fernandez and his team first need to solve the camera problem, one of the first is, what kind of signals does the human retina generate? To understand the problem, Fernandez removed the retina from the eyes of the deceased, connected it to the electrode, and exposed it to light to understand the electrode’s signal.
His team also used artificial intelligence technology to match the electrical signals of retinal output to simple visual inputs. This helps them write software that automatically simulates the process.
The next step in the experiment is to transmit electrical signals to the brain. In an artificial vision system developed by Fernandez for Gomez, a cable is connected to a multi-channel neural electrode (slightly smaller than the positive pole raised by a AAA battery).
The multi-channel neural electrodes have 100 micro electrodes — each about 1 mm long — that look slabs like miniature nail beds. Each electrode can transmit current to 1-4 neurons. When a multichannel neural electrode is implanted in the patient’s head, the electrode passes through the surface of the brain.
The multi-channel neural electrode has 100 micro electrodes that look like a miniature nail bed
Fernandez had to calibrate one electrode after another, gradually increasing the current until Gomez produced an optical illusion. Optical illusion refers to the feeling that the retina, when it is not stimulated by mechanical stimulation, electrical stimulation, etc., instantaneously feels like it sees light. It took Fernandez more than a month to complete the calibration of all 100 electrodes.
“The advantage of our technology is that the electrodes of multi-channel neural electrodes penetrate into the brain, very close to the nerves,” Fernandez said, which allows artificial vision systems to produce vision that significantly reduces the risk of spasms in patients, just as much as the electrical current slots in the Dobelli system.
One of the major shortcomings of this artificial vision system, and the main reason gomez’s test duration cannot exceed six months, is that no one knows the normal life of the electrodes. “The body’s immune system starts to attack the electrodes, creating scar tissue around the electrodes — weakening the signal,” Fernandez said. “
Electrode bending is also a problem to be solved. Based on animal experiments and the multi-channel neural electrodes that Gomez tried, he believes the current system can be used normally for 2-3 years, or as long as 10 years.
Fernandez hopes that the optimized multichannel neural electrode life could be extended to decades. Life is an important prerequisite for medical devices that require brain surgery.
Ultimately, like cochlear implants, artificial vision systems need to transmit signals and electrical energy wirelessly to the electrodes if they are to become truly popular. But for now, Fernandez’s system still needs a wired connection, and many iterations are needed in the future before it can finally be formed.
If the resolution is 10 x 10 pixels – the maximum resolution of the system That Gomez is trying to use , people may feel basic shapes such as letters, door frames, and sidewalks , but that resolution is not enough to feel the contours of the face, let alone humans. That’s why Fernandez has graphics recognition software for his system, which helps gomez see people in the room.
Fernandez wrote in a PPT that after a resolution of 25 x 25 pixels, it is possible for patients to regain “vision.” Because the current multichannel neural electrodes are very small in size and require very little current, there are no technical barriers to installing 4-6 on each side of the brain, which can provide 60 X 60 pixels or even higher resolutions, he said. But one problem is that it is not clear how many signals the brain can receive from multichannel neural electrodes without overloading them.
What it’s like to use an artificial vision system
Fernandez and his graduate student connected a prototype camera to a computer
Gomez said she would have been using Fernandez’s artificial vision system if possible. After a new version comes out, she will first apply for a trial. After Fernandez completed the analysis, Gomez planned to hang the multi-channel neural electrodes she had tried on the living room wall as a souvenir.
At Fernandez’s lab, he gave me a chance to try out the noninvasive equipment he used to examine patients.
I sat in the leather chair where Gomez had been sitting last year, a neurologist holding a wand with two rings attached to both sides of my head. The device, called a butterfly coil, is connected to a box that stimulates neurons through electromagnetic pulses — a phenomenon known as transcranial magnetic stimulation.
The first stimulus made me feel as if someone was knocking on the scalp, and my fingers were curled completely. “There’s a reaction, and it’s your motor cortex that stimulates it,” Fernandez said. Now we’re going to try to make you feel the illusion of light. “
The neurologist adjusted the position of the wand and raised the pulse frequency. When she turned on, I felt pretty strong, as if someone had used my back door as a ring.
Although I opened my eyes, there was a vision: a bright horizontal line across the center of my field of view, and two flashing triangles (the inside was like snowflakes on a TV screen when there was no signal). These illusions can be said to come and go in a hurry, go also hurriedly, only stay for a short time.
“It’s very similar to Gomez,” Fernandez said. “The difference between me and Gomez is that she sees the outside world, and all I see is the illusion that the brain is stimulated by electromagnetic pulses. (Author/Frost Leaf)