Elon Musk has declared that his Blindsight cortical implant to restore sight may “ultimately exceed normal human vision”.
But new research from the University of Washington (UW) suggests the billionaire entrepreneur’s own vision may have exceeded basic rules of human biology.
Dr Ione Fine, lead author and UW professor of psychology, said Musk’s projection for the latest Neuralink project was unrealistic, at best, and rested 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, would result in high-resolution vision.
For the study, published online July 29 2024 in Scientific Reports, the researchers created a computational model that simulated the experience of a wide range of human cortical studies, including an extremely high-resolution implant like Blindsight.
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 recognisable.
On a computer screen, pixels are tiny ‘dots’. But that’s not the case in the visual cortex. Instead, the researchers said 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,” Dr 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 a pixels on a computer screen.”
Even blurry vision would be a life-changing breakthrough for many people, Dr Fine said, but these simulations – which represent the likely best-case scenario for visual implants – suggest that caution is appropriate.
Dr Fine said Musk was making important strides in the engineering challenge of visual implants, but a big obstacle remained: Once the electrodes were implanted and stimulating single cells, one still needs to recreate a neural code – a complex pattern of firing over many thousands of cells – that created good vision.
“Even to get to typical human vision, you would not only have to align an electrode to each cell in the visual cortex, but you’d also have to stimulate it with the appropriate code,” Dr Fine said.
“That is incredibly complicated because each individual cell has its own code. You can’t stimulate 44,000 cells in a blind person and say, ‘Draw what you see when I stimulate this cell’. It would literally take years to map out every single cell.”
Scientists still had no idea about how to find the correct neural code in a blind individual.
Without that sort of development, the vision provided by Blindsight and similar projects would remain fuzzy and imperfect – no matter how sophisticated the electronic technology.
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