One of the upsides of a complex neurochemical/biological pathway such as sight is that there are many ways of tackling the same problem. Although the complexity makes the solutions complex as well, at the very least it guarantees that there are multiple avenues to explore. Researchers from Weill Cornell Medical College have combined several of these avenues to create a retinal prosthetic for mice that gives them an ability to perceive things around them that is unparalleled.
Previous research had shown that introducing light-sensitive proteins in the retina, which is sometimes damaged in the blind, can enhance vision. The retina, treated thus with gene therapy, is then better able to simulate the output cells — the ganglion cells — to send along the electrical impulses to the brain.
Below is a crude little mockup of the process of vision, as I understand it. Click to enlarge; WordPress isn’t kind to these images.
But Nirenberg and Pandarinath believed that another crucial piece of the puzzle had to be taken care of for the entire system to operate well: they had to able to replicate the pattern of electrical impulses produced by the eye’s circuitry, and make sure that those impulses correctly simulate the scene that is being observed. Their research into the “code” that needs to be generated between light hitting the rods and cones of the retina, and the ganglion cells sending signals to the brain, revealed that this pattern could indeed be artificially simulated.
In short, they’ve built a system of an encoder, which breaks down images entering the eye into electrical impulses, and a projector that converts the electrical impulses into light impulses. The latter then stimulates the genetically enhanced proteins in the ganglion cells.
They’ve now gone on to crack the “code” of vision in monkeys, and hope to be starting human trials soon.
Another proposal for restoring vision that I saw recently involved a much simpler, but potentially far less useful technique. Berkeley scientists discovered that regular injections of a chemical called AAQ restored a degree of photosensitivity to mice that were formerly blind, aiding them in converting light to electrical impulses and eventually to images.
Perhaps combined with, or replacing the gene therapy step in the above research from Cornell, vision prosthetics/enhancement might become a reality in the next few years. It’s particularly interesting, to me, to see how the various methods of attacking the problem of sight have resulted in a multi-disciplinary, multi-faceted system like this. It’s cumbersome, but it works.
ExtremeTech has an extended article on this, with image comparisons of the enhanced and non-enhanced systems. The differences are quite stunning.
And now for the obligatory Curiosity news!
Everyone’s favorite Mars rover is doing well, as is NASA’s reputation at the moment. I spent most of today surreptitiously reading this Reddit thread (Ask Me Anything) which featured the scientists and engineers from the Curiosity team. And yes — it did include Mohawk Guy.
Some truly fascinating stuff that came out of this included the fact that NASA has a fledgling Planetary Protection Guidelines page. I say fledgling because a) it’s impossible to predict how we should react to alien civilizations when they haven’t been found, and b) we’re still not sure we’re anywhere close to finding them. Most of it is prosaic stuff, like “let’s be very clean so we don’t contaminate anything!” but I suspect directives like “always wait for the alien to introduce itself!” are just waiting in the wings.
A geek can dream.