Eye transplant

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Eye transplant

Postby Ideas sleep furiously. » Tue Aug 02, 2011 7:52 am UTC

I asked my Bio teacher this, and she was stumped.

"If you were to get an eye transplant (assuming they are possible) from an animal that could view the UV spectrum, could you observe UV light?"
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Re: Eye transplant

Postby AvatarIII » Tue Aug 02, 2011 8:49 am UTC

personally, i'd guess your brain wouldn't know what to do with the information, so even if the eye could "see" it, you would not be able to comprehend it.

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Re: Eye transplant

Postby yurell » Tue Aug 02, 2011 9:10 am UTC

You don't need an animal eye to see ultraviolet — the blue cones are quite sensitive in the ultraviolet, but your lens blocks it. If the lens is removed, you may be able to see ultraviolet.
I doubt your brain can interpret the signals sent from the eyes of another animal, though.
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Re: Eye transplant

Postby Interactive Civilian » Tue Aug 02, 2011 10:11 am UTC

Let's make a "consider a spherical cow on a frictionless plane" style assumption. ;)

Assume: You are somehow able to transplant the eye perfectly with a 1 to 1 matching of axons in the optic nerve.

If you could do that, and the transplanted eye had receptors sensitive enough to UV and a lens and vitreous humor that passed UV, then yes, you would be able to see UV. However, the UV receptors are going to be linked to certain neurons which will carry that impulse through the optic nerve to the brain. If you have the assumed 1 to 1 mapping, then that UV sensitive impulse is going to trigger your brain seeing whatever color was originally received on that line. If it replaced a red cone, for example, then UV would appear red in your perception, because your brain has learned over its time that input from those receptors is interpreted as "red". Well it's actually more complex than that, as the brain is comparing multiple inputs against each other to mix colors and form images from the stimulated receptors. A lot could depend on if the UV receptors are replacing all of a certain color or just some of them. If it were replacing some of each of the red, green, and blue receptors, then it would be even more a mess. Basically, the upshot is that colors would be mixed wrong and the world would appear strange (perhaps like looking at a computer screen with very bad color balance and colors being mixed all wrong). Perhaps the brain could adapt (it's very adaptable), but it's impossible to say what you would actually perceive.

Perhaps more interesting would be if the rods were more sensitive to UV. Your night vision would be shot to hell (not a lot of UV around at night), but there might be weird, subtle shading to the world out of the corners of your eyes during the day.

Remember, your brain is merely interpreting signals it receives from the nerves of the sensory organ. Hundreds of millions of years of evolution (for the vertebrate eye and brain) have caused your brain to interpret signals coming down the optic nerve as due to light. However, if you could connect an eye to the olfactory area of the brain or the nose to the visual cortex, then you would smell light and see scents respectively. However, it is unlikely that the brain could make sense and understand patterns of such drastic changes in input. Or so it seems to me.
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Re: Eye transplant

Postby Tass » Tue Aug 02, 2011 10:37 am UTC

If you still have only trichromatic vision, then it is just the colors that are mixed up. Like IC says for example UV becomes red etc (I'd probably keep the order and let blue take over UV). What that would look like can be easily simulated with technology. For a couple thousand bucks I could build you a pair of goggles that will do that.

If you want to transplant fourchromatic vision then you are going to have - big - trouble.

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Re: Eye transplant

Postby Ideas sleep furiously. » Tue Aug 02, 2011 11:33 am UTC

Thank you for all your replies, I was thinking somewhere along the lines of those, amongst other, crazy, things.

Ok another question, how do you think a bee would observe objects which we observe as being red?
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Re: Eye transplant

Postby yurell » Tue Aug 02, 2011 11:51 am UTC

I'd imagine they'd experience as a superposition of other colours. Our own perception is what we get once our brain has processed signals from our eyes — a superposition of signals from 'red', 'green' and 'blue' cones. These don't react to just one wavelength each, though, they have their own response curves, so any colour is our own perception of a mixture of different ones.
So I suppose bees process this information differently — bees don't see red, it looks black to them, but they can detect three 'colours': UV, green and blue. Everything they see is a superposition of these colours.

I'm not a biologist btw, so if one contradicts me take their word for it ^_^
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Re: Eye transplant

Postby Shivahn » Tue Aug 02, 2011 6:38 pm UTC

We see the spectrum like this.

While I doubt anyone can say for sure what bees perceive a given color as, without that red cone, they're going to see what we see as red as a much fainter green (since the green is their lowest wavelength cone, all that they will see past it is green until the cone stops being able to receive the photons entirely).

On the other hand, where we just see blue, bees can likely see awesome colors and distinguish very precisely between them, just like we can where the green and red cones intersect.

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Re: Eye transplant

Postby Qaanol » Tue Aug 02, 2011 7:14 pm UTC

Well I for one see the color red as totally different from and way more awesome than how you see the color red.
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Re: Eye transplant

Postby Shivahn » Tue Aug 02, 2011 7:41 pm UTC


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Re: Eye transplant

Postby quantropy » Wed Aug 03, 2011 8:07 am UTC

Mice can normally see in two colours, but if they are genetically modified to have a third receptor then their brains seem to be able to use it.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC208822/

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Re: Eye transplant

Postby Sockmonkey » Thu Aug 04, 2011 1:52 am UTC

IIRC it's been claimed that some women have a fourth color receptor.

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Re: Eye transplant

Postby BlackSails » Thu Aug 04, 2011 2:16 am UTC

The retina is part of your brain, so you would need to do a brain transplant for this to work!

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Re: Eye transplant

Postby masher » Thu Aug 04, 2011 5:29 am UTC

BlackSails wrote:The retina is part of your brain, so you would need to do a brain transplant for this to work!


What?

The retina is most definitely part of the eye. If you're referring to the optic nerve joining the eye to the brain, then by that reckoning, anything connected to a nerve is part of the brain...

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Re: Eye transplant

Postby Carnildo » Thu Aug 04, 2011 11:13 am UTC

Sockmonkey wrote:IIRC it's been claimed that some women have a fourth color receptor.

You're referring to tetrachromacy. Green-sensitive cones come in two variations, with slightly different ranges. Since the gene for the pigment involved resides on the X chromosome, it's possible for a woman to have both variants. The expected result is that human tetrachromats will have a slightly greater ability to distinguish shades of green than trichromats.

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Re: Eye transplant

Postby Tass » Thu Aug 04, 2011 11:50 am UTC

Couldn't the brain technically use data from the rods as well as the three types of cones for some degree of tetrachromatic vision?

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Re: Eye transplant

Postby Technical Ben » Thu Aug 04, 2011 4:44 pm UTC

AvatarIII wrote:personally, i'd guess your brain wouldn't know what to do with the information, so even if the eye could "see" it, you would not be able to comprehend it.

From the studies I've seen (granted, they were reported on in the media, print and physorg.com) the brain can make sense of any input you give it.
As an example, learn to use a remote controlled car. Or respond the the sensations given through a rumble controller on a games console. You brain uses the inputs like they were natural and always there. It takes time, but it can be learnt. If your sending a signal to the brain that there is ultra violet light in a certain spot of your vision, your just activating some neurons. Eventually, the brain will eventually figure out "this neuron turned on" means "this part of the retina active" which means "I see *something* there". Then we learn it's ultraviolet through context.

Can we mentally comprehend it? There was a study on if a person could build up an extra sense. They used a digital compass and some electrodes. No, they did not implant them in anyone, just wore them on a belt. After a month or so, the users were able to use this direction "sense" to navigate very well, even blind folded. The sensation was similar to that of balance I guess.
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Re: Eye transplant

Postby Angua » Thu Aug 04, 2011 5:04 pm UTC

masher wrote:
BlackSails wrote:The retina is part of your brain, so you would need to do a brain transplant for this to work!


What?

The retina is most definitely part of the eye. If you're referring to the optic nerve joining the eye to the brain, then by that reckoning, anything connected to a nerve is part of the brain...

The retina is formed from the diencephalon which is an offshoot of the brain, so I'm guessing that this is where the misunderstanding is. The optic nerve is classed as central nervous system (rather than peripheral) and as such will not regenerate if cut (peripheral nerves can regenerate, though not very much). So, in a sense the retina and optic nerve are part of the brain, though I'm not sure if you'd need a brain transplant - just someway to get the optic nerve to heal.
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Re: Eye transplant

Postby Carnildo » Fri Aug 05, 2011 4:38 am UTC

Tass wrote:Couldn't the brain technically use data from the rods as well as the three types of cones for some degree of tetrachromatic vision?

Technically, yes. In practice, there's very little overlap in the brightness sensitivity ranges, so that the rods are producing a signal of "pure white" at about the same time as the cones start producing useful data.

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Re: Eye transplant

Postby Technical Ben » Fri Aug 05, 2011 6:28 am UTC

Is it not just the same as adding an additional colour? If the signals from the retina are additive, we are only going from "original signal" to "original signal + 1". The brain would just make a colour (give a reading) greater than violet.
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Re: Eye transplant

Postby Sockmonkey » Fri Aug 05, 2011 1:20 pm UTC

I think it's more like if the range of colors your eyes can see goes from 4 to 8, a 7 would be interpreted as 3.5 by the brain.

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Re: Eye transplant

Postby Tass » Fri Aug 05, 2011 6:11 pm UTC

Sockmonkey wrote:I think it's more like if the range of colors your eyes can see goes from 4 to 8, a 7 would be interpreted as 3.5 by the brain.

Technical Ben wrote:Is it not just the same as adding an additional colour? If the signals from the retina are additive, we are only going from "original signal" to "original signal + 1". The brain would just make a colour (give a reading) greater than violet.


Another sensor would give a whole other dimension of possible perceptions. It is way more than just extending the rainbow, the gamut it spans gains a dimension.

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Re: Eye transplant

Postby Technical Ben » Sun Aug 07, 2011 5:51 pm UTC

See "other senses" for an example of how the body just absorbs and interprets other dimensions. There is a couple of examples of people being born with poor eyesight and never developing sterioscopic (3d) vision. Later in life, an operation or glasses fix the problem. They have to learn how to see in 3d. No difference from babies doing this, but as adults they can describe the effect.

I don't see the brain having any trouble at all. Really it's hard to set an upper limit there defiantly is one, but it's not going to be "one".
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Re: Eye transplant

Postby idobox » Tue Aug 09, 2011 1:11 pm UTC

The thing with that kind of transplant, is it takes a lot of time for the brain to reroute itself.
Transplanting a human eye would probably involve monthes of crazy color, until your brain reroutes green cones to green neurones (much simplified, but you get the point).
Is the brain able to learn to interpret a fourth color?
The transgenic mices tend to show it would be able if the transplant happened at a young age.
Exposing transgenic mice to a world in two colors (by using colored lighting for example) until they are adult could show if the adult brain is able to reroute itself to integrate a new color.
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Re: Eye transplant

Postby tearcastle » Tue Aug 09, 2011 1:28 pm UTC

Qaanol wrote:Well I for one see the color red as totally different from and way more awesome than how you see the color red.


I feel bad for you

Interactive Civilian wrote:Let's make a "consider a spherical cow on a frictionless plane" style assumption. ;)

Assume: You are somehow able to transplant the eye perfectly with a 1 to 1 matching of axons in the optic nerve.

If you could do that, and the transplanted eye had receptors sensitive enough to UV and a lens and vitreous humor that passed UV, then yes, you would be able to see UV. However, the UV receptors are going to be linked to certain neurons which will carry that impulse through the optic nerve to the brain. If you have the assumed 1 to 1 mapping, then that UV sensitive impulse is going to trigger your brain seeing whatever color was originally received on that line. If it replaced a red cone, for example, then UV would appear red in your perception, because your brain has learned over its time that input from those receptors is interpreted as "red". Well it's actually more complex than that, as the brain is comparing multiple inputs against each other to mix colors and form images from the stimulated receptors. A lot could depend on if the UV receptors are replacing all of a certain color or just some of them. If it were replacing some of each of the red, green, and blue receptors, then it would be even more a mess. Basically, the upshot is that colors would be mixed wrong and the world would appear strange (perhaps like looking at a computer screen with very bad color balance and colors being mixed all wrong). Perhaps the brain could adapt (it's very adaptable), but it's impossible to say what you would actually perceive.

Perhaps more interesting would be if the rods were more sensitive to UV. Your night vision would be shot to hell (not a lot of UV around at night), but there might be weird, subtle shading to the world out of the corners of your eyes during the day.

Remember, your brain is merely interpreting signals it receives from the nerves of the sensory organ. Hundreds of millions of years of evolution (for the vertebrate eye and brain) have caused your brain to interpret signals coming down the optic nerve as due to light. However, if you could connect an eye to the olfactory area of the brain or the nose to the visual cortex, then you would smell light and see scents respectively. However, it is unlikely that the brain could make sense and understand patterns of such drastic changes in input. Or so it seems to me.


And i think there is a disorder where you sort of "see sounds" or something

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Re: Eye transplant

Postby Sockmonkey » Wed Aug 10, 2011 12:20 am UTC

http://en.wikipedia.org/wiki/Synesthesia
Lost of creative people had it.

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Re: Eye transplant

Postby BlackSails » Fri Aug 12, 2011 11:58 am UTC

idobox wrote:The thing with that kind of transplant, is it takes a lot of time for the brain to reroute itself.
Transplanting a human eye would probably involve monthes of crazy color, until your brain reroutes green cones to green neurones (much simplified, but you get the point).
Is the brain able to learn to interpret a fourth color?
The transgenic mices tend to show it would be able if the transplant happened at a young age.
Exposing transgenic mice to a world in two colors (by using colored lighting for example) until they are adult could show if the adult brain is able to reroute itself to integrate a new color.


The brain would never adapt imo, a lot of the vision system is hardwired and/or hardwired after a few months old.

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Re: Eye transplant

Postby AvatarIII » Fri Aug 12, 2011 12:27 pm UTC

I actually saw a relevent documentary about this very subject the other day (UKers can catch it on iplayer until 19th september)
in one part of it, they implanted cone receptors into the eyes of colour-blind monkeys and they instantly were able to see colour (as proven by computer screens showing Ishihara tests, and the monkeys got food by touching the right part of the screen, AND they did a thing so the monkeys could learn to only press when the colour corresponded to nice tasting food.)

so it wasn't really an eye transplant, but it proved that adding new receptors to the eye, the brain can almost instantly begin processing the new information in a useful way.

edit: on further research it turns out that it was actually gene therapy, not direct application of cone receptors (damn dumbed down television) that caused the monkeys to be cured of colourblindness
http://news.discovery.com/animals/color ... erapy.html
Last edited by AvatarIII on Fri Aug 12, 2011 12:43 pm UTC, edited 1 time in total.

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Re: Eye transplant

Postby idobox » Fri Aug 12, 2011 12:33 pm UTC

AvatarIII wrote:but it proved that adding new receptors to the eye, the brain can almost instantly begin processing the new information in a useful way.

This is a surprise to me. I was expecting at least a few month for the brain to be able to reroute itself.
I can't watch the video. Do they give experimental details?
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Re: Eye transplant

Postby AvatarIII » Fri Aug 12, 2011 12:46 pm UTC

i have edited my post above. but they didnnot give much detail on the experimental results, it was a pretty dumbed down doc, i'm sure if you are really interested you can find out some more details.

also you may be able to view iplayer with a proxy, i am not sure, i have never had to try (i have managed to watch Hulu from the UK using a proxy before so it should work on the same principal)

also (2) it was a surprise to me too.

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Re: Eye transplant

Postby BlackSails » Fri Aug 12, 2011 8:37 pm UTC

AvatarIII wrote:I actually saw a relevent documentary about this very subject the other day (UKers can catch it on iplayer until 19th september)
in one part of it, they implanted cone receptors into the eyes of colour-blind monkeys and they instantly were able to see colour (as proven by computer screens showing Ishihara tests, and the monkeys got food by touching the right part of the screen, AND they did a thing so the monkeys could learn to only press when the colour corresponded to nice tasting food.)

so it wasn't really an eye transplant, but it proved that adding new receptors to the eye, the brain can almost instantly begin processing the new information in a useful way.

edit: on further research it turns out that it was actually gene therapy, not direct application of cone receptors (damn dumbed down television) that caused the monkeys to be cured of colourblindness
http://news.discovery.com/animals/color ... erapy.html


The brain already knows how to interpret color, it was the eye that was defective in sensing. Adding wholly new sensors is a whole different thing than adding sensors that were supposed to be there all along.

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Re: Eye transplant

Postby AvatarIII » Sat Aug 13, 2011 12:37 am UTC

BlackSails wrote:
AvatarIII wrote:I actually saw a relevent documentary about this very subject the other day (UKers can catch it on iplayer until 19th september)
in one part of it, they implanted cone receptors into the eyes of colour-blind monkeys and they instantly were able to see colour (as proven by computer screens showing Ishihara tests, and the monkeys got food by touching the right part of the screen, AND they did a thing so the monkeys could learn to only press when the colour corresponded to nice tasting food.)

so it wasn't really an eye transplant, but it proved that adding new receptors to the eye, the brain can almost instantly begin processing the new information in a useful way.

edit: on further research it turns out that it was actually gene therapy, not direct application of cone receptors (damn dumbed down television) that caused the monkeys to be cured of colourblindness
http://news.discovery.com/animals/color ... erapy.html


The brain already knows how to interpret color, it was the eye that was defective in sensing. Adding wholly new sensors is a whole different thing than adding sensors that were supposed to be there all along.


i'm pretty sure squirrel monkeys are always colour blind

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Re: Eye transplant

Postby Sockmonkey » Sat Aug 13, 2011 5:54 am UTC

If something's primary diet is mostly fruit, they generally see in color.

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Re: Eye transplant

Postby yurell » Sat Aug 13, 2011 6:15 am UTC

cemper93 wrote:Dude, I just presented an elaborate multiple fraction in Comic Sans. Who are you to question me?


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Re: Eye transplant

Postby TheDancingFox » Sat Aug 13, 2011 6:51 am UTC

Honestly, the plasticity of the brain is pretty consistently underestimated. Even systems that are 'hardwired' in still change and adapt to circumstances. I would say that, if this could be feasibly done such that the brain was getting different signals from UV light or any other new spectrum it would in time work out a proper balance and one would be able to properly distinguish their vision. There was an experiment at one point, which I unfortunately cannot point anybody to, that involves the wearing of this patch on the lower torso, particularly sensitive area, which would send I believe minuscule electric shocks, minor enough not to be any kind of pain, just to register. Eventually, the wearer came to recognize the differences in the signals and was starting to perceive them distinctly and follow their patterns as understandable information. Less extreme than adding a new spectrum of vision (or more extreme, depending on your perspective, I suppose), but the point is a similar one: the brain is daaaaamn good at shifting to include new circumstances and inputs such that it can properly interpret them.

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Re: Eye transplant

Postby idobox » Sat Aug 13, 2011 5:18 pm UTC

AvatarIII wrote:on further research it turns out that it was actually gene therapy

That means we have, right now, technology able to give new receptors to primates. It means we could do it to humans too.
How many of you believe armies around the world are working on giving their soldiers UV and IR vision?
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Re: Eye transplant

Postby AvatarIII » Mon Aug 15, 2011 2:15 pm UTC



yeah that's what i was talking about, it seems that all males and 1/3 of females are colour-blind,

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Re: Eye transplant

Postby TrlstanC » Wed Aug 31, 2011 7:22 pm UTC

TheDancingFox wrote: There was an experiment at one point, which I unfortunately cannot point anybody to, that involves the wearing of this patch on the lower torso, particularly sensitive area, which would send I believe minuscule electric shocks, minor enough not to be any kind of pain, just to register. Eventually, the wearer came to recognize the differences in the signals and was starting to perceive them distinctly and follow their patterns as understandable information.


Here's a story on how that research is being put in to use now. I've seen a number of reports/studies of similiar set ups, and the results are all basically the same. The brain will recognize signals sent to different parts of the body as visual information, and process it correctly. Stimualting the tongue will allow people who have lost their site to have limited B&W vision. The brain demonstrates some amazing capability to process new (or new sources of) information.

Assuming we did some kind of experiment that involved an eye transplant (or adding IR receptors to someone's eyes), what I'd really be interested in finding out is what color they see the IR light in. The way I think about color (which is filled with wild assumptions since our knowledge in this area ia very limited) is that the brain uses the qualia to label (or paint) our visual field. Areas which trigger the same types of cones, and send impulses down the connected nerves get labeled a certain way. So, fire hydrants, apples and exit signs all get the same label. And we can interpret signals that weakly activate two different kinds of cones as a label (color) in between those two. Basically, color just tells us what things are the same, and what are different.

Having a 4th kind of cone to detect IR light would mean there's more information, how would we experience the new information (what label would the brain apply)? I think there's two possibilities:

1. The brain figures out that IR comes after red, and then just streches out the whole spectrum of colors that it uses to represent colors. This makes the assumption that the color spectrum we see represents all the "labels" the brain has available. So, if we now had access to more information it would have to make use of the same labels, but just apply them to different information. Bright IR would look like bright red, red would get pushed down a bit, so fire trucks and apples would be more orangeish now, ect.

2. The brain figures out that IR comes after red, but it turns out that it has some extra colors lying around it wasn't using. So, it takes one, and applies it to IR, bright IR would be purely this new color, and less bright IR would look Redish/IRish. Everything else would stay the same, except you could also get new shades that were the mix of the 4 primary colors.

Of course, telling the difference between the two would only be possible for someone who used to see 3 colors, and now sees 3. If someone was born with the ability to see IR they could never comunicate if their red looks like our red. Or what color IR looked like to them.

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Re: Eye transplant

Postby idobox » Wed Aug 31, 2011 8:45 pm UTC

TrlstanC wrote:The brain figures out that IR comes after red,

I don't see how the brain could figure that out. We had to wait until Newton, I think, to understand there is an order in the colors.

But yes, it would be very interresting to try that. A subject with normal color vision could have a IR camera linked to the tongue thingie and tell us.
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Re: Eye transplant

Postby TrlstanC » Wed Aug 31, 2011 8:52 pm UTC

idobox wrote:
TrlstanC wrote:The brain figures out that IR comes after red,

I don't see how the brain could figure that out. We had to wait until Newton, I think, to understand there is an order in the colors.


I was just assuming that the red cones would be partially activated by IR light (well, we wouldn't call anything IR we can see, but that end of the spectrum) and the IR cones would be partially actived by red light. There wouldn't be that overlap anywhere else. I guess we can't really know what the brain is capable of "figuring out." At least not without some tests, any volunteers??


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