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National Eye Institute
07/30/2024 | Press release | Distributed by Public on 07/30/2024 13:34
U. Washington computational model shows cortical implants unlikely to exceed normal human vision
July 30, 2024
NIH-funded researchers, including U. Washington's Ione Fine, created a computational model that simulates the experience of a wide range of human cortical studies, including an extremely high-resolution implant. Their model suggests implants are unlikely to exceed normal human vision. They published a report on their model in Scientific Reports.
Researchers are exploring devices that can be implanted into the brain - bypassing the eye - to create vision. But according to Fine, these devices rest on the flawed premise that implanting millions of tiny electrodes into the visual cortex, the region of the brain that processes information received from the eye, will result in high-resolution vision.
Fine and colleagues' model simulates the experience of a wide range of human cortical studies, including an extremely high-resolution implant. One simulation shows that a movie of a cat at a resolution of 45,000 pixels is crystal-clear, but a movie simulating the experience of a patient with 45,000 electrodes implanted in the visual cortex would perceive the cat as blurry and barely recognizable.
That's because a single electrode doesn't represent a pixel, Fine said, but instead stimulates, at best, a single neuron.
On a computer screen, pixels are tiny 'dots.' But that's not the case in the visual cortex. Instead, each neuron tells the brain about images within a small region of space called the "receptive field," and the receptive fields of neurons overlap. This means that a single spot of light stimulates a complex pool of neurons. Image sharpness is determined not by the size or number of individual electrodes, but the way information is represented by thousands of neurons in the brain.
"Engineers often think of electrodes as producing pixels," Fine said, "but that is simply not how biology works. We hope that our simulations based on a simple model of the visual system can give insight into how these implants are going to perform. These simulations are very different from the intuition an engineer might have if they are thinking in terms of pixels on a computer screen."