Check into it and ask about the impact of retinal remodeling on potential interventions.

Nossir. That is not correct. See my comment just above.

Yes. Precisely.

[sigh].... do not feed the troll.... do not feed the troll...

OK, I'll feed the troll. Yes, I am acutely aware of Paul Bach-y-Rita's work. You however apparently do not understand the concepts that you are invoking. There is plasticity in neural systems, yes. Plasticity is important in vision, sure. Nobody, *anywhere* has demonstrated that they can generate coherent "visual percepts" in a coordinated fashion with any kind of stimulus. Its far more complicated than hooking up electrodes and stimulating until someone "learns" what the stimulus means.

btw, the tongue thing is very, very cool. Its not vision and does not even map to vision, but those lingual electrodes can easily map topographic data, sonar data, relief data, contrast data onto the high resolution innervation of the tongue and allow people to interpret those stimulii as a map to be followed. The technology was originally developed for US Navy SEALS to navigate complex 3D environments at night, with no light and it works. It works incredibly well with very little training necessary. I would like to see more effort and funds put into techniques like that to help people live more independent lives.

I am familiar with Nirenberg's work. What Nirenberg seems to be missing is that the programming outflow of the retina is altered in retinal disease. ON and OFF channels are substantially altered in retinal disease and the whole programming substrate is altered because the circuitry and programming down to the molecular levels is altered.

Its not all pessimism though as we will need to understand how the normal retina signals and I find her work to be interesting and compelling. Though she is not addressing *which channels* of information outflow are being encoded. There are 14-16 separate outflow channels in the retina that project to different areas of cortex and sub cortex and she is not addressing how to separate those channels and what those separate channels mean in terms of the "visual world".

This is just my point. While I understand that science and engineering has to start somewhere, they have made promises to this woman and done surgery to her, potentially increasing risks for other problems where I would argue there is no hope of "seeing" anything coherent.

Yes, we can do remarkable things with even an 8x8 pixel array, but this approach has no promise of even delivering that to this woman. The electrode cuff on the optic nerve simply stimulates too many neurons that are not coherent and those neurons project to far too many areas of cortex. A retinal implant that appropriately targets cell populations would be more appropriate as would genetic engineering of targeted opsins to other cell classes.

As for implants directly in the cortex, I might argue that this has a better chance of stimulating phosphenes that could be interpreted as vision. I've participated in some of that early work http://prometheus.med.utah.edu/~bwjones/2009/08/bionic-implants/ and while I believe there are other approaches that will be more effective, that work still has some promise (particularly for motor interfaces).

Ah, ad hominem attacks from an Anonymous Coward... You will note that I am an "eye doctor". What are your qualifications to call someone else a clown?

We'll see... I would have liked to have seen some traditional methods of evaluation in animal models using psychophysics before moving directly to humans. Were I a betting man, I don't think the engineering is up to the biological task right now. A couple decades work already suggests that we don't yet understand how the information is coded to get into the brain.

Yeah, its easy for people to get enthused about rescuing vision loss. Its an important thing and keeps us working at all hours of the day as hard as we can to understand how the visual system works and how to fix it when it goes wrong. We've published before on this issue and I am sure they are aware of the work. My only concern is when promises are made to patients and expectations are built up that these devices will cure blindness when the biology has not been worked out and the engineering is predicated upon that imprecise understanding of the biology.

For the first part, see my comment to femto above.

As for the neurons changing their behavior, yes... that is exactly what I am saying. It definitely happens in the retina as the retina is reprogrammed and there is some evidence that it happens higher up as well. Though those precise studies have yet to be performed.

So, flashes of light are simply uncoordinated signaling by neurons. Turns out vision is far more complicated than the cochlear system that allows us to engineer bionic solutions for hearing. Provided the cochlea is intact, it is easy to stimulate those neurons in an appropriate manner that people can learn to interpret. Vision is another story entirely and unless you stimulate the *right* neurons with the *right* type of stimulation, its not gonna work.

So, which ganglion cell populations are they going to stimulate? The optic nerve contains from 14-16 classes of ganglion cells that project to different areas of brain. Its a tough tough problem because those ganglion cells and the axons in the nerves project not only to LGN, but also to a large number of subcortical areas like the SCN and tectum. Then what about the remnant signals that may be coming from peripheral regions of the retina (in cases of AMD) and central retina (in cases of RP)?

Again, they are moving forward with engineering without necessarily understanding the biology.

What they are claiming is that the bionic implant will work in a degenerate retina. The substrate circuitry has changed. No chance of it transducing vision... They are either going to have to intervene at an earlier time point (much earlier than most folks realize) or bypass the retina or reconstruct the retina. There is more biology at play here than a simple engineering project.

Note: This is *NOT* vision. This is an uncoordinated stimulation of neurons that is no more vision than poking your eye and seeing flashes of light or knocking yourself on the back of the head and seeing stars. Vision is a far more complicated matter and these investigators that are promoting this bionic chip have ignored or are ignorant of over a decade of research that shows the neurons in the eye change their wiring in response to retinal degenerative disease. When the wiring in the retina changes, it is no longer able to mediate normal retinal signaling...

Yes, I am a vision scientist.

Dude... I've been washing my keyboards for years. Spill coffee in them? Run EM under the tap and dry them out. Spill beer in it, stick it in the dish washer. Air dry.