That's not so obvious to me. If this chemical were uniformly spread across the retina, then I'd agree. But if it's sufficiently clumpy, or ideally attached to every second green-sensitive cone, then it absolutely would give (N+1)-colour vision (N=3 in humans). On first glance I can't figure out what the paper has to say about this distribution... and even if it were uniform in their mice, perhaps the next step would be to make it non-uniform somehow.
The earlier way to do something similar was by genetically altering some cells, [1]. If you inject a virus (carrying the modification) at a low concentration, then you do get just half the cells. Then the brain learns (in a few weeks) which cells are now giving what information, and you get more colours. [1] did this in monkeys, IIRC they are N=2 and the virus added the gene for one of the human receptors. I don't think it was safe enough for humans.
[1] https://www.nih.gov/news-events/nih-research-matters/gene-th...
I don't think you are born with different wiring to the three different kinds of cones, your brain just learns to lump all the red ones together, so that a red object stays the same colour in different parts of your visual field. The claim is that the monkeys learned which of the previously-identical cones now had a new colour.
Do they lose any sleep philosophising about how these new colours are possible, and what to call them? Who knows. But I believe they can still do all the usual monkey things.
That's the point they can not distinguish more colors. Their retinal cones still have the same spectral response. They cannot distinguish between a normal 500nm green leaf and a 900nm infrared source.
The monkeys are in a different study, the one I linked a few posts above.
The nanoparticles sound to me like they could be safer? Would be interesting to know whether they can be non-uniformly spread, so that only half the green cones can see one.
Given that, and the tactical advantage of seeing NIR in low light situations, someone is going to try this on people. And the results of that study could have a lot of impact.
I was thinking this was cool because if it works in the cornea, it could possibly be injected into a contact lens and achieve the same effect. But it looks like that won't work because the effect depends on the chemical being in (very) close proximity to photoreceptors in the retina.
She didn't tell her boss because she had disabled the safety switch, for some reason that seemed good at the time.
"A process in which two photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with twice the energy of the initial photons. In some cases, almost 100% of the light energy can be converted to the second harmonic frequency. These cases typically involving intense pulsed laser beams passing through large crystals, and careful alignment to obtain phase matching. In other cases, like second harmonic imaging microscopy, only a tiny fraction of the light energy is converted to the second harmonic."
a) The chemical put into the retina is surprisingly biocompatible, in that it does not appear to have caused anything out of the ordinary to happen. It works by effectively converting IR light to visible light - so it does not involve ‘sending more data’ to the brain, or ‘opening another colour band’ or anything like that. It is seen as just plain old green light, because the crystal structure of the chemical basically converts 980nm~ IR to 500~nm visible green light. So no uber-neurohacking going on here.
b) The procedure they are using to put the chemical in place is fairly run-of-the-mill medical procedure for humans for treatment of eye diseases, albeit a little icky.
So, I’m surprised, to say the least, but this could actually work with humans as a fairly harmless enhancement. I’m still waiting for the other shoe to drop, but haven’t seen one in the study itself for the time being. (Disclosure: not an expert, but I follow related fields)