In the Neuralink presentation yesterday, Musk put vision restoration front and center. He specifically said this would work for the congenitally blind because they still have a visual cortex.
Two hundred years of experiments on site restoration in human, and many fundamental cellular experiments of visual development and the limits of adult plasticity, show this is false.
I hope Neuralink picks a better goal for the advanced technology they are building.
@wandell Giles Brindley stimulated the visual cortex of a blind nurse (in the 1960s) and produced patterns of phosphenes. So it could work. in principle. Bur the problem is the spatial resolution if it is to be good enough for tasks such as reading text.
@dickretired The important Brindley and Lewin experiments were performed on an adult who was previously sighted. Congenital and adult onset have very different characteristics. There is good reason to hope that implants might be effective in adult cases. The retinal implants are a good way forward in some cases. See Pixium, Sahel, Palanker.
@wandell @dickretired I agree that early-onset and late-onset blind are going to be different. There's a lot more anatomical and functional reorganization that happens with early-onset blind that it will make functional recovery harder.
It's known that artificial cochlear implants need to be done really early to gain speech perception. I know the outcome is quite good for late-onset deaf. But for early-onset deaf with late implant the outcome is much poorer, because the adult auditory cortex cannot properly use the information coming from the implant. I expect similar will be true for the visual implants.
Generating phosphenes are good, but there's more to visual processing if you want to navigate in a 3D world.
@dickretired @hkl @wandell This paper is not about late vision restoration in early blind with an implant but via surgery, yet may be viewed as a likely best possible result with a near-perfect implant: https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC4500636&blobtype=pdf "Together, these findings provide little evidence for recovery of high-level visual function after more than a decade of visual experience in adulthood". A visual cortical prosthesis therefore likely offers little benefit to early blind adults.
@dickretired @hkl @wandell An interesting anecdote is also that one of the Dobelle brain implant recipients who had gone blind at age 18 initially experienced stimulation of his "visual" cortex not as phosphenes but as beeps https://amazon.com/dp/1479709204/ p. 430 ff.
@seeingwithsound @dickretired @wandell
That certainly is interesting! Hearing beeps is expected if there was auditory recruitment of the visual cortex. I wonder if the percept ever changed to phosphenes?
@hkl @dickretired @wandell Yes, some days later, Dennis apparently for the first time saw phosphenes in a test session, saying "I don’t see anything. All there is are these flashes of light." https://amazon.com/dp/1479709204/ p. 446 ff.; and after finding a test object from its flash, "I wouldn’t call that seeing. It’s just a flash of light, that’s all. It could have been anything".
@seeingwithsound @dickretired @wandell That is quite interesting that the percept changed to see phosphenes... May be that's because this person had vision before? I certainly will read the book.
@hkl @dickretired @wandell Yes, the case of Mike May has shown that brain plasticity wipes out a lot of earlier visual development even if one had normal eyesight up to age 3. I highly recommend the book by Jens Naumann (Search for Paradise, about the Dobelle brain implant). Heavy stuff, but good antidote for company talk such as that from Neuralink. I know Jens personally, as he visited me several times at my home.