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Biotech Science

Single Gene Gives Mice Three-Color Vision 184

Posted by kdawson from the colors-you-can't-see dept.
maynard writes "A study in the peer-reviewed journal Science shows that mice transgenetically altered with a single human gene are then able to see in full tri-color vision. Mice without this alteration are normally colorblind. The scientists speculate that mammalian brains even from animals that have never evolved color vision are flexible enough to interpret new color-sense information with just the simple addition of new photoreceptors. Such a result is also indicated by a dominant X chromosome mutation that allows for quad-color vision in some women." A sidebar in the article includes a nice illustration of what two-color vs. three-color mice might perceive.
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Single Gene Gives Mice Three-Color Vision More

Single Gene Gives Mice Three-Color Vision

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  • I, for one, welcome our new full-spectrum-observing mice overlords...

  • Quad = 4?? (Score:5, Funny)

    by blakmac ( 987934 ) <blakmac@gmail.com> on Saturday March 24, 2007 @03:14PM (#18472961) Homepage
    "Such a result is also indicated by a dominant X chromosome mutation that allows for quad-color vision in some women."

    Are you kidding me? You know darn well that women can see at least 75 shades of off-white...

  • Question I couldn't get from the article (Score:5, Interesting)

    by reezle ( 239894 ) on Saturday March 24, 2007 @03:15PM (#18472975) Homepage
    Did they provide gene therapy to the mice which then gained color vision, or did they alter the mice before birth? Is it possible to insert genes into an adult organism and permanently change their DNA structure?

    • Re:Question I couldn't get from the article (Score:4, Informative)

      by jstomel ( 985001 ) on Saturday March 24, 2007 @03:39PM (#18473173)
      This gene would almost certainly have to be inserted before the eye develops, as it affects the type of "cone" cells that develop in the eye. Also, gene theropy into retinal is very difficult because (thank god) there are very few viruses that infect retinal cells.

      • Also, gene theropy into retinal is very difficult because (thank god) there are very few viruses that infect retinal cells.

        Don't thank god for that, thank natural selection. A virus that impairs its host's vision is not going to get much time to reproduce itself.

        • Don't thank god for that, thank natural selection. A virus that impairs its host's vision is not going to get much time to reproduce itself.

          Now you've got me curious thinking about all of the viruses I know of, to see if any of them are prone to leap to dead ends (such as you describe).

          Do you know of any viruses that do 'stupid' things? I would imagine there must be some (or were, perhaps?), even viruses fall under the scrutiny of natural selection .. I would assume.

          Interesting thought if you find yourself

          • AIDS and Ebola come to mind, with Ebola being the dumber one. I assume that it's much less virulent in its normal (unidentified) host.

            Really, all the viruses floating around can still move up the virus social ladder by incorporating its DNA with the DNA of its host, as much of human DNA might have been virus DNA in the distant past.

            • Re: (Score:2)

              by Anpheus ( 908711 )
              The Ebola virus and the Marburg virus are probably the 'dumbest' in that they both kill their host far, far too rapidly to allow widespread contamination. There are other viruses that cause similar symptoms, hemorrhagic fever and the like, and they're all fairly dumb. Had either virus affected a major airport, the contamination would have been huge. We're extremely fortunate (well, we are... the people affected, not so much) that so far outbreaks have been in small villages where relatively few people are a

            • Re: (Score:2)

              by Fastolfe ( 1470 )
              HIV doesn't seem to fit the definition of a "dumb" virus, in my opinion. Infected individuals live years, and have ample time to spread the virus on to other people. A "dumb" virus would kill the individual it infected before the virus could be spread to others, thus limiting its ability to survive.
          • Generally the nasty viruses are ones that cross over from other species and do weird things because of it. Almost universally a pathogen does not dramatically reduce the survival of the host in the original species. There are viruses that are nasty all over (which is why I said almost universally), but there is mounting evidence to support that they are either heavily mutated or from an extinct species.

        • Re: (Score:2)

          by hey! ( 33014 )
          Depends on opportunity.

          Viruses don't "care" whether they kill their hosts, they just mutate. Sometimes in ways that kill their hosts. If you have enough hosts, more aggressive mutations survive.

          Also, viruses may play an ecological role as a kind of natural defense. You have a population of critters in an area and they're all infected with a virus they more or less tolerate. Another population of critters comes in to take their niche, but being immunologically unprepared, they die.

          The reason that it's

    • Re:Question I couldn't get from the article (Score:5, Interesting)

      by Tatarize ( 682683 ) on Saturday March 24, 2007 @05:40PM (#18473983) Homepage
      What you really want to know is if they develop some of these genes to give you superpowers can you have them or do we need to genetically engineer ungrateful children to be able to whoop us.

      The latter is the case. Your eyes are destined to suck forever. You can't see infrared or ultraviolet, you can't see like a hawk, nor can you get the lungs of a bird, the electro-sensing power of a platypus, ability to freeze solid like a toad, smell things as well as a dog, hold your breath like a whale. Even simply fixes like giving humans the ability to make their own vitamin C (every mammal has that save great apes and guinea pigs). No fixing the mammal eye so the all the blood and nerve don't run in front of the lens. No fixing the recurrent laryngeal nerve so that it goes from the brain straight to the larynx rather than looping around the aortic arch for no reason at all.

      We could however, perhaps give such changes to our kids, those ungrateful little snot-filled twerps. You'll have to live being a social thin-haired ape who can play with fire and kill just about anything after making the tool for the job.

      • I agree and disagree; simply doing the gene therapy won't make your body magically regrow your retinas to be tetrochromatic. However, if you grew a clone of yourself using the modified DNA, you could then do a retina or eye transplant. If we also did the genetic mods to allow out bodies to regrow organs and limbs, then maybe you could simply remove part of the eye and let it regrow with the new feature.
      • The latter is the case. Your eyes are destined to suck forever.

        Can you comment on the 'why'? IIRC from physiology, all of our cells, save the nerve cells, are replaced every 7 years or so.

      • Re: (Score:2)

        by mgblst ( 80109 )
        Yes but surely we can steal these super eyes of these children? Hopefully that is still a possibility.

    • Yes and no (Score:5, Informative)

      by DrYak ( 748999 ) on Saturday March 24, 2007 @06:30PM (#18474289) Homepage

      Is it possible to insert genes into an adult organism and permanently change their DNA structure?

      Yes.
      It depends off your target site, but yes it is possible.
      - You can replace bone marrow (remove a mutated one that led to cancer, and put another one (given from a relative) that is exempt of the broken gene that lead to the cancer). As you are modifying stem cells (blood cells precursors) the modification is rather permanent. And as the newly produced white blood cells are always re-trained after creation they won't consider your body as foreign so you won't have immune system rejection (graft vs. hosts in this case). And as a bonus, because bone marrow cells have homing capabilities, they're as easy as a blood transfer to inject. But the problem is that, during the time between when you radiated the old marrow to kill the cancer and when the newly injected one has finished recreating white cells, there's a window during which the organism is defenseless against infections.
      - Viruses are small things that basically work by injecting their genetic information (DNA or RNA) inside a host cell. Scientist can assemble small virus like things that use the virus shell and thus are able to inject their material, but inside they contain the gene you need to add for the therapy. As far as I've heard there were attempt to use such a system to treat mucoviscidosis (by injecting a gene to help produce working chloride channels). It is administered as a spray. The problems are (beside the high cost of such a method) that the spray only reach the supperficial layer of cells in the bronchus. These are differenciated cells that don't multiply anymore, they only do their work until they die off and fall out. The precursors are deeper and not affected by the therapy. Thus the effects aren't permanent. Plus, after some time the hosts immune system ends up discovering those modified virus and/or infected cells, considers them as foreign and develops antibodies against them. Thus the therapy gets ineffective after some times. Thus the whole idea was scrped and now we mostly use drugs that are cheaper, makes the cells work using the gene they already had before (other ion channels - carbocystein) or directly dilutes the secretions (acetylcystein), and whose effect doesn't diminish with time (thus they are much more effective at reducing the speed of degradations of lungs and buying time before lung transplantation gets necessary).

      Did they provide gene therapy to the mice which then gained color vision, or did they alter the mice before birth?

      No.
      Transgenic mice = before birth gene modification.
      For the mutation to work, it has to happen /before/ the brain and the retina gets wired. The colour perception capabilities develops when the nervous fibres grow and connect to different population of receptors.
      You can't 'cure' colour-blindness with gene therapy alone.

      Technically speaking, there are virus that can infect retina before birth. But they would be much more difficult and expensive to produce, plus they can have bad side effects, and they are harder to control if they did inject their genes. Also the whole stuff is less ethical for the poor mice. Right now, you modify the mice at the stage of either zygote (1 single cell) or not-yet feconded gamete. You let the zygote do a couple of division, you get one of the dozen cell and check it the gene is still in place. If it is, you implant the stuff in a mother mouse. With the virus way, you have to inject the virus into a mother mouse while she still carries the baby mice (and hope that there won't be too much side effects - inflamation and such - for the mother or the mice she carries), then once the baby mice are born, you have to screen them to see which one carry the new gene (and has them into the eyes. The virus can target several organs, and won't necessarily infect the mice's eyes. I don't know, but maybe removing one of the eyes could be the only solut

    • It's highly unlikely that adding genes or even an entire new eye could increase visual range, unless perhaps it was done immediately after birth. The Wikipedia article on Critical Period [wikipedia.org]s is a bit lacking so I'll do this post from memory: basically there are narrow windows in the development of an organism where particular skills can be acquired, and if you miss out during that period you will probably never acquire the ability.

      Language acquisition is a good example - if a child is, say, abandoned and raise
    • Just give me a cybernetic implant. Preferably with a laser-pointer attached.

      RESISTANCE IS FUTILE

  • True colour (Score:1, Interesting)

    by LiquidCoooled ( 634315 )
    I had my first taste of this recently.

    We live in a colour society and think when we point a camera at a target and click we take a faithful picture of it.
    I was wrong.

    I have pictures taken from a recent concert where the camera saw one colour (blue) but the actual colour was violet, it was strange holding it up and seeing it filtered then moving it out of the way to see the real colour.

    does anyone know if there are such limitations with original developed camera film, or is it just not noticed?

    • Re: (Score:3, Interesting)

      by Jott42 ( 702470 )
      Most definitly. No color reproduction technology in existence has the capability of reproducing all the colours that the human can experience. (i.e. the Gamut, nice reading in Wikipedia: http://en.wikipedia.org/wiki/Gamut [wikipedia.org] )

      • Re: (Score:3, Insightful)

        by grumbel ( 592662 )
        The fun part is that even a perfect reproduction of what a human can see would still be only a tiny minority of what is actually there. This is most easily demonstrated with a TV remote and a digicam, which registers the IR light, which the human eye doesn't. Other side effects is that the human eye will register certain very different mixtures of wavelength as the exact same color, while a digicam will register them as two different ones.

    • Re:True colour (Score:5, Interesting)

      by 19thNervousBreakdown ( 768619 ) <<davec-slashdot> <at> <lepertheory.net>> on Saturday March 24, 2007 @03:41PM (#18473179) Homepage

      Violet is especially tricky. Its wavelength is shorter than blue, but in addition to stimulating your blue cones, your red cones are also slightly sensitive to it. The camera, however, sees the pure, very deep blue. Then, when it goes to display it on the LCD, it only turns on the blue pixel instead of the blue and a little red.

      Another thing that people don't generally notice is that the RGB pixels or phosphors don't match up perfectly with everyone's cones. The only way I can think of to have faithful color representation is to have one "pixel" on both camera and display that is sensitive to and can emit any visible frequency of light, with perfectly flat response. IOW, maybe flying AI-controlled cars will have a camera/display like that.

      • Re:True colour (Score:5, Informative)

        by blueish yellow ( 838971 ) on Saturday March 24, 2007 @06:18PM (#18474219)
        Violet is especially tricky. Its wavelength is shorter than blue, but in addition to stimulating your blue cones, your red cones are also slightly sensitive to it.

        This doesn't make any sense. Red cones are not sensitive to blue light. Here is a diagram [utah.edu] showing the sensitivities of of the three cones (S, M, and L or Blue, Green and Red) in our retina whose signals combine to create color.

        Our perception of color comes from the combination and comparison of the stimulation of three different cones, each maximally sensitive to different wavelengths. The output of the cones gets combined in what are called opponent pathways, one is Red-Green, and the other is Blue-yellow. The Red-Green pathway compares the output of the Red and Green cones and the Blue-yellow pathway compares the output of the blue cone with the sum of the red and green cones. This is why you will never see a color that is reddish-green or blueish-yellow (see nick) at least in the additive sense that red+blue=violet and yellow+blue+green.

        So why does extremely short wavelength light appear to contain a reddish component? I don't believe that anyone knows the answer to that yet. But the hypothesis is that somewhere along the path from cone to cortex the input from a blue cone and red cone combine which turns our perception of an extremely short wavelength light into a combination of short wavelength light (blue) and extremely long wavelength light (red). So our sensation of color becomes a continuum that loops back on itself as opposed to our sense of pitch (which is also frequency or wavelength).

        Interestingly people who have had their lenses removed are somewhat able to perceive ultraviolet light. This is because the lens ordinarily blocks UV light and blue cones are sensitive to UV light but very little ever penetrates to the retina normally. Apparently they see it as lilac.

        Many mammals, fish, birds, insects, and reptiles (basically everyone except us) are able to see UV light as well. It's a good that we can't for two reason. One is that there is more chromatic aberration at shorter wavelengths. Basically blue light bends more than red light. This makes focusing more difficult. Also, more importantly, UV light damages DNA which is a very, very, bad thing. This [handprint.com] is a good resource for learning more.

    • Your camera might have been playing with the white balance. When the ambient lighting is not perfect white, sometimes digital cameras will compensate. Taking a picture with no flash indoors will look yellowish with a film camera because incandescent lighting is yellowish. Point & shoot digital cameras will compensate for this by shifting the colours towards blue.

      Or maybe your camera's display does not show red well. Or maybe you used a long exposure and the camera's sensor is slightly less sensitive to

  • possible use in humans? (Score:5, Interesting)

    by dunkelfalke ( 91624 ) on Saturday March 24, 2007 @03:16PM (#18472987)
    is it possible to genetically alter humans to make them tetrachromats, thus making them able to see UV like fishes and birds do?

    • Re: (Score:2)

      by maeka ( 518272 )
      If humans were simply given sensors for UV, would that be enough?
      Can the human eye focus UV light, or would the ability to perceive it simply add more noise and glare?
    • No, because corneas and lenses block most of the UV spectrum anyway.
    • Perhaps, if a human could be genetically altered to have a type of cone in their eyes which received UV light. All known tetrochromats, as discussed in this article, however, have a 4th cone able to receive light somewhere between the red and green frequencies. That allows them to perceive the normal human colourband in much greater detail than I can, but they can't see in UV.

      More importantly, they can't see in IR. To me, having heat vision would be way cooler.
  • That'd be pretty neat. Except that they'd never be able to tell the rest of us what it is like.

  • Squant (Score:3, Funny)

    by Threni ( 635302 ) on Saturday March 24, 2007 @03:24PM (#18473047)
    I'm holding out until I can see Squant: http://negativland.com/squant/index.html [negativland.com]

  • Martian colours (Score:5, Interesting)

    by Dogtanian ( 588974 ) on Saturday March 24, 2007 @03:27PM (#18473075) Homepage
    One issue I find interesting in this context is the guy who was colour-blind (that is, he couldn't differentiate colours in certain parts of the spectrum). This guy had synesthaesia [wikipedia.org], and although he couldn't physically see certain colours, he could experience them through his synesthaesia. He referred to them as "Martian colours".

    The interesting implication here is that the GM mice's brains apparently developed with the ability to process the new colours. It would be fair to assume that ordinary mice's brains did not even contain the "concept" or "perception" of red hardwired in, since what would the point be?

    Thus, if the converse is true, and human brains develop the same way as mice's, it could be assumed that the brains of people with the *physical* inability to detect certain colours from birth would never develop the mental concept/sensation of those colours. (*) But then, now does this explain "Martian colours"?

    (*) (If you're having trouble understanding what I mean, try to imagine what ultraviolet "looks" like. Darklight (UV lamp) special effects don't count; that's *visible* light produced when UV hits special fluorescing material. And you can't "cheat" by imagining in terms of false colours (since that, by definition, is *converting* UV to visible-range colours). No, I want you to try to imagine what colour actual UV light would look like... and you'll fail because you've never directly seen UV light, and the concept isn't wired into your brain).

    • The simple explanation, that doesn't require hardwiring colors into the brain (which raises extremely tricky questions with both your synesthaesia guy and your mouse), is that the brain, or even eye, which does a surprising amount of visual processing, recombines the individual cone information it gets into at least some approximation of a full spectrum

    • One issue I find interesting in this context is the guy who was colour-blind (that is, he couldn't differentiate colours in certain parts of the spectrum). This guy had synesthaesia, and although he couldn't physically see certain colours, he could experience them through his synesthaesia. He referred to them as "Martian colours".

      If he couldn't differentiate colours then how could he be said to be "experiencing colours" (albeit through synesthaesia) -if he was experiencing the colours in any non-random way

      • Re: (Score:2)

        by Epistax ( 544591 )
        The brain is really screwy. If I see a vehicle, or anything of an obvious color, and I am not looking directly at it, while I know what color it was, I cannot connect it to the word. It feels like when you just can't remember the word for something. It's kind of fun to play with and almost 100% reliable. In this case I can see the color, and I can differentiate it, however not with my speech.

        Interestingly enough (to me) if the color on the edge of my vision is a significant light source, say, an LED in

      • Most importantly, I don't know whether the person in question was able to demonstrate that his "martian colours" actually enabled him to discriminate between objects of different colour

        No, NO, NO!!!!! As I already said to the AC above.... the whole point was that the guy could neither see nor differentiate these colours in the real world. In other words, he was born with a genuine colour blindness to certain parts of the spectrum and could not differentiate such colours in the real world.

        There was no magic going on with his eyes; he genuinely couldn't perceive this colour. What he *could* do was to experience the "unattached" sensation of red (or whatever the missing colour was) throug

        • If he could see the colour in any sense at all then he should have some discriminatory ability. If he has no discriminatory ability, then we have no evidence that he experiences colour at all -do you understand? If he can't produce any evidence suggesting he can see colours, then he can't -period. We need evidence to believe things. If he can't discriminate at all then he is not experiencing colours -he is experiencing an artifact of unorganized neural crosstalk.

          Let me put it another way, if he can't dis
        • I carefully reread your post and I get what you're saying now. I don't know if this is a case of misreading on my part or miswriting on your part. Either way, I understand now the situation you are describing. If I'm not mistaken, my response to your original post is applicable to this case.
          • The problem with discussing this is that it raises very philosophical issues about what "experiencing" colours is, what the human concept of "colour" in itself is (as distinct from the simple frequency of light), and given this what the "true" meaning of certain words are.

            Regarding proof, we have to make reasonable assumption that the guy is not lying, and trust that he is competent to judge that what he is "experiencing" is the *sensation* of colour, even though this sensation has not been produced as a

    • Re:Martian colours (Score:4, Interesting)

      by toonerh ( 518351 ) * on Saturday March 24, 2007 @04:30PM (#18473469)
      The occipital lobe of the brain (visual processing) - even in adults - can retrain itself to flip the view after wearing inverting glasses, ignore the distortion from "progressive" glasses (for old people like me) and quickly compensate for different colored lighting.

      It seems quite possible a mouse's brain could classify groups of cones, especially since they would be obvious from birth on.

    • Re: (Score:2)

      by Kjella ( 173770 )
      I think the brain will come up with a concept for whatever input it's getting. I don't think it matter if the eye got one or three or seven different kinds of receptors, it would make them up as needed. The difference is really whether the input is shot, or the link somewhere between input and output is shot. If we look at people that are red-green colorblind, are 1/3rd of their receptors dead? No, they fire off as usual. It's the backend that doesn't differentiate them, but they could detect colors in some

      • If we look at people that are red-green colorblind, are 1/3rd of their receptors dead? No, they fire off as usual. It's the backend that doesn't differentiate them, but they could detect colors in some other way, e.g. Martian colors.

        For the third time, in this particular case (where I came across the term "martian colors") the guy was genuinely colourblind and could not see/differentiate these colours in the real world; he could only experience the abstract (or not-so-abstract) sensation via synesthaesia. See this reply [slashdot.org] and this reply [slashdot.org].

    • try to imagine what ultraviolet "looks" like.

      Doesn't seem hard to me. We know exactly where it exists on the spectrum. It would simply be a higher-frequency version/shade of purple/violet.

      • Doesn't seem hard to me. We know exactly where it exists on the spectrum. It would simply be a higher-frequency version/shade of purple/violet.

        No, I meant imagine that you can see UV as a distinct colour; in other words, if you had a fourth set of separate UV cones in addition to red, green and blue-sensitive ones. If it were simply a case of the short-wavelength (blue/violet) cones' sensitivity extending into the UV, you'd be able to "see" it, but not differentiate it from blue (i.e. experience it as a distinct colour). This has happened with people who've had cataract surgery [slashdot.org], and they report sensing the UV simply as intense purple.

        On the oth

        • Re: (Score:2)

          by SEE ( 7681 )
          Even with unenhanced sight, your subjective experience upon seeing 700 nm light might be identical to the subjective experience I get seeing 500 nm light. We would both call the color at 700 nm "red" because it's the name we were both taught to give to our experience, but to you I might "really" be experiencing blue.

          Then there's the next step. We might not even have that much commonality. The experience of red as you experience it might not be the same as any color I am capable of experiencing or imagini
          • Yes; I see what you're saying, and it's a philosophical can of worms. :-)

            The issue you raise is interesting, and of course important, but somewhat distinct from the point I was trying to make. That is, even if we assume that the experience of two trichromats with broadly equivalent optical sensors (i.e. eyes) is the "same" for a given colour, or- to make it even simpler- if we only care about our own experience of colour, there is still no way for a normal trichromat person to "imagine" the sensation of c
    • Could synesthaesia include the "feeling" of music? If so, I think more than 1 in 23 people may have synesthaesia to some degree or another. My wife who "likes" music does not seem to experience it like I do and when I talk to her about what I feel when I experience music, it does not seem to reach as deeply into her psyche and it does to me.

      This does not seem to be related to musical skills; she can play piano, I can't play a darned thing even though I tried very hard to learn. Yet music (of many types) i

    • Re: (Score:2)

      by zobier ( 585066 )
      I know someone who smoked some DMT and said he "saw" colours he'd not experienced before, among other strange things.

  • Still no proof of 'full' spectrum vision (Score:5, Interesting)

    by nietsch ( 112711 ) on Saturday March 24, 2007 @03:28PM (#18473085) Homepage Journal
    Although their GM mouse made M and L type cones in their retinas, it is still not clear if what they reacted to was only a change in intensity, or if they could see a true difference between the two colors. Normal mouse are essentially colorblind in that region of the spectrum, red triggers the M receptor, but not very much, so you need a brighter red light to stimulate the M receptor equally as greenish light. Since you need a very good control, the test setup was such that normal could not see a difference between the red and green light. Their GM mouse were much more sensitive to red, so to them the red light must have had a much brighter intensity. But that does not mean their brains had adapted themselves to differentiating between red and green light. To test that you would have to measure the sensitivity of the new red receptor and adjust your intensity to that so that the only difference is in the color, not the intensity. The problem offcourse is that you cannot do that same experiment with normal mouse which have a different red sensitivity, and no control == bad science.
    So their claim that the GMs mouses brain really processed the red light signal different from the green might be a bit over the top.

    (hmm thinking about it, if the GM mouse cannot discern between red and green, there might be a certain redlight intensity where their scores would drop significantly, while the controls would score better. If you cannot find that, my hypothesis is wrong and their claim is right. Now lets see if I can find if they did that test...)

    • Re:Still no proof of 'full' spectrum vision (Score:4, Insightful)

      by DeadCatX2 ( 950953 ) on Saturday March 24, 2007 @04:41PM (#18473569) Journal
      We label as red the neuro-signal which is a lot of activation by the L cone, and almost no activation of the M or S cones.

      So, you can't even say that what we see as "red" is actually red at all. When a certain wavelength of light hits a bunch of cones, they each send their own response to that stream of photons to the brain, encoded as an SML signal, so to speak, and red is just some specific SML signal. Our brain then interprets the S, M, and L information and composes an "image" of the color. A lot of L and a little bit of M and S looks like red.

      So, if the M and L cones are processed by the same neuro-circuits, then yes, they just saw an increase in intensity. Stimulation of an M or L cone would cause the same area of the brain to respond, and since red is more towards L, then that area of the brain would see more activity than it normally does in the non-GM mice, assuming M and L signals activate the same neurons.

      However, if the M and L cone data are processed in different areas, then I would believe that they indeed see different colors.
      • That the brain needs to wire the different colors to different regions to percieve colors. That does not need to be the case, as neural nets are very good at distinguishing different signals in the same space. The brain just sees the correlation between the red pwallops and fusitales them into amorpholous sets. So you don't need different regions to proces different sensors.
        • My remark about M and L cones activating the same neurons, was that the mouse usually has an SM signal. I assumed that this meant there would be two paths to the brain, and that would encoding a gene for an L cone would create a similar L path to the brain, or if the L signal would be multiplexed on top of the M signal.

          Think of it like component cables. Mice have G and B connected, and R disconnected. Does the R signal go through some sort of merger before getting plugged back into G? That was my questi
    • Some researchers think human's are "blocked tetrachromats" [4colorvision.com]. The fourth group of cones in this case is in the near ultra-violet, not refining green, yellow and red. Further, the lens of a normal human eye absorbs those UV wavelengths so strongly that the UV cones mostly see dark. Only when the lens is removed, as cataract surgery, are the UV cones activated.

      I don't know how accepted this theory is, plus current physiology can't fully map the nerves of the retina to the brain.
  • And now it is the time on slashdot when we dance.
  • What do those graphics look like to you?

    • Re: (Score:2)

      by canavan ( 14778 )
      I have no idea how someone with color blindness sees them, since I only have some red/green deficiency. But why rely on a description when you can try for yourself [wickline.org], with numerous forms of color blindness.

      • I have no idea how someone with color blindness sees them, since I only have some red/green deficiency. But why rely on a description when you can try for yourself [wickline.org], with numerous forms of color blindness.
        Neat! Thanks for the information.

    • Re: (Score:2)

      by ozbird ( 127571 )
      Did you want colour blind test images [toledo-bend.com], or people with colour blindness?

      I probably have protanomaly [wikipedia.org]. Distinguishing red and green isn't a problem at all, but I do see different shades of red and brown to other people (e.g. cheap Rubik's cubes with a darker shade of red than the original look maroon to me.) On one occasion, a normal sighted birdwatcher pointed out a Scarlet Robin in a tree that I couldn't see until I looked at it through binoculars, when the bird "popped out" with it's bright red breast.

      • Did you want colour blind test images [toledo-bend.com], or people with colour blindness?
        The latter, I'm wondering if you guys see the two images as identical (or near enough).
        That would depend on the types of color blindness that correspond to the mice's point of view, of course.

        • Re: (Score:2)

          by ozbird ( 127571 )
          They' quite different for me, but my colour vision is probably akin to adjusting the colour temperature on your monitor. Except for extreme cases like the "colour blindness" tests, I don't notice any issues with my colour vision.

  • A sidebar in the article includes a nice illustration of what two-color vs. three-color mice might perceive. [hhmi.org]

    ... thus explaining why mice show no outward tendencies towards jealousy or violence, and behave in a highly cautious manner at all times.

  • > Mice without this alteration are normally colorblind.

    No. They are dicromats.

  • The Ducks Win It! (Score:5, Interesting)

    by DynaSoar ( 714234 ) * on Saturday March 24, 2007 @07:59PM (#18474915) Journal
    Ducks are pentachromats. They have 5 different receptors for color. That doesn't mean they see other colors than we do, but it does mean they have better color differentiation. I can think of no other explanation other than ducks evolved from artists.

    Maybe we can put them to work testing monitors. Your garden variety graphics card and monitor are already capable of producing more colors (4.28 million or some such) than humans can differentiate (3 to 3.5 million).

  • Women only? (Score:2, Insightful)

    by salimma ( 115327 )
    If the tetrachromatic mutation affects a single dominant gene in the X chromosome, why is it that it is only expressed phenotypically in females? Men have a single X chromosome too -- in fact, we are more adversely affected by inherited traits such as colour-blindness for the precise reason that we only have a single copy (thus a recessive mutation would be more likely to be manifested, since there's no "normal" version of the gene to suppress it).

    • Re: (Score:2, Informative)

      by Tacvek ( 948259 )

      If the tetrachromatic mutation affects a single dominant gene in the X chromosome, why is it that it is only expressed phenotypically in females? Men have a single X chromosome too -- in fact, we are more adversely affected by inherited traits such as colour-blindness for the precise reason that we only have a single copy (thus a recessive mutation would be more likely to be manifested, since there's no "normal" version of the gene to suppress it).

      The X codes for red and green cones. The fourth color perc

  • "I can see clearly now, the brain is gone, I can see all obstacles in my way..."

    Very sorry
  • Looking at the side-bar that shows us what non-genetically modified mice see, does their absence of red vision mean that I could make a better mouse trap just by painting a plain old mousetrap red?
  • can they see Octarine [lspace.org]?

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