There are about 36 million blind people in the world. Scientists and doctors are trying to evolve technology that will allow the blind person plug in a camera to a wire that connects directly to the brain, The brain then reads the signal and then regains rudimentary vision, depending on the size of Utah array, the cluster of electrodes that touch the brain. The greatest advantage of this technology is that it completely bypasses eye and optical nerves – the medical condition of which is the most frequent cause of blindness.
That said, it is quite risky to implant a device inside the brain. Brain surgeries are risky. A prosthetic apparatus may not be in the skull for long. Researchers of this technology cannot do experiments on animals, as cats and monkeys cannot describe what they see.
Blindness is a severe condition – some people are not able to see light at all. However, with an implant, they may be able to see the ceiling light, the basic shape of objects on paper, doors, elevated platforms, letters, envelopes and similar things. To some extent one can even play video games. This is because implant has electrode array, or cluster, of 10×10, or 100 electrodes. This is similar to a raster scan. More the number of pixels, more detailed turns out to be the view. To identify people and emotional face contours technology may require much denser array than that, i.e. more than 100 electrodes.
During six-month window, patient can see a very low-resolution outline of the world represented by yellow-white dots and shapes. The apparatus that makes this possible contains modified pair of glasses, with black frame and fitted with a tiny camera. The arrangement is connected to a computer that processes a live video feed, and turns it into electronic signals. A cable then links the system to a port embedded in the back of skull of the human subject that is wired to a 100-electrode implant in the visual cortex area in the rear of her brain.
Restoring sight by sending signals to brain directly is medically ambitious. However, underlying principles have been used in implants in mainstream medicine for decades. There are cochlear implants for deafness and pacemakers for heart. Artificial vision, or bionic vision as stated more appropriately, has to be removed after six months. Brain tissues surrounding the implant detect it as presence of foreign material. To resist it can develop scars, which can cause infection. Scars can degrade the signal quality or signals can then damage the brain.
At 25×25, or 625 electrodes, vision is possible. Utah array, at 60×60 pixels vision will be as good as healthy vision. However it is risky surgery and electrodes have to be touched to brain one at a time. Post removal periodic MRI scans may be recommended to check for any traces of surgery left behind. Also, there is no virtual evidence of the metal outlet in the back side of her neck. Patients were still excited about trying out the assembly in first place. Most patients do not experience pain or surgery post removal.
Roots of this technology can be traced back to 1929. German neurologist named Otfrid Foerster first discovered that he could trigger a white spike in the vision of a patient if he touched electrode into the visual cortex of the brain while doing surgery. He named the phenomenon as phosphene. Since then scientists and sci-fi authors have imagined the possibility for a camera-computer-brain interlinked visual prosthesis. They built rudimentary systems around it.
In the early 2000s, eccentric researcher named William Dobelle tried to turn hypothesis into reality when he installed biomedical inside the head of an experimental patient. In 2002, writer Steven Kotler witnessed horrific seizure of that patient as the later fell to the floor, writhing in pain when Dobelle turned on the power supply. Dobelle’s system probably lacked gentleness, there was probably more current and more stimulation – brain could not bear. Patients had problems with infections in this system. Yet, Dobelle marketed it as cure for blindness, created promotional video of a blind man driving a car slowly and ready for day-to-day use. Dobelle’s death in 2004 also killed his prosthesis with him. Another researcher named Eduardo Fernandez, built gentler though external system where subjects had better results and also left them happy.
What kind of signal does a human retina produce? To try to answer this question, researchers take human retinas from recent corpses, touch the retinas to the electrodes, expose them to luminosity, and measure what is collected by the electrodes. Human retinas can remain alive for seven hours maximum. They then use machine learning to match retina’s electrical output to simple visual inputs, which helps them write software to mimic the process automatically.
The next step is to take this signal and deliver it to the brain. A cable connects to a common neuro-implant, Utah array, smaller than raised tip on the positive end of a AAA battery. Protruding from the implant are a millimeter tall, 100 tiny electrode spikes. This looks like miniature bed of nails. Each electrode delivers current between 1 to 4 neurons. On insertion there are 100 piercings on the brain. On removal same number of blood droplets form in the holes. It takes about a month to insert 100 electrodes.
As it evolves, the prosthesis, similar to cochlear implant, will have to transmit its signal and power wirelessly through the skull to reach the electrodes. Externally bundled prosthesis is flexible and easier to upgrade. Design can be settled upon if this becomes a trend.
When the phenomenon of phosphene occurs, as patient explains, a bright horizontal line flashes at the center of line of sight, along with two shimmering triangles filled with what looks like snow flake on TV. The vision fades as quickly as it arrived, leaving a brief afterglow. On turning around their head, with his glasses on, patient can see outlines of objects, he would want to touch he had not been able to do in years. “It feels somewhat artificial, yet it is definitely useful,” concludes another patient.