It's like this fragment of "The Little Prince" when he draws an elephant in a snake and adults say it's a hat. You can put white sheet and when people say "Oh, you dressed as a ghost" you'll say: "Wrong, it's retina protein" :D
Your explanations are so amazing! In almost every single one of your videos, you express a concept that isn't explained all that often in a simple, humorous, and surprisingly informative fashion. There is no unnecessary simplification, it follows the science beautifully, and everything is put together just right. This channel is one of my favorites on all of UA-cam and I never hesitate to share your new videos after watching them. I hope you go right to the very top.
Well, there's always simplification. For example, why does light cause the molecule to switch from cis to trans? It has to do with a radical mechanism of isomerization. Why does the molecule's shape and its interaction with proteins change the frequencies it absorbs? That has to do with the wavefunction of the electrons and delocalization/resonance. I think Steve is really good at choosing precisely the right things to leave out to tell a coherent story, and that makes him a very good educator. He'll rise to the same prominence as Veritasium or VSauce if UA-cam let him.
There are some snakes that got heat vision. They got cells that work similar to a microbolometer pixel below their noses. It's just 6 pixels but the anatomy allows them to combine the signal greatly and locate something to eat in the darkness. It's likely responsive to 6-12micron wavelengths. Which almost fit into LWIR thermal cameras. There is a great paper with low of images that show a modified therma imaging camera to represent what said snake and "see". It's a difficult evolutionary questions because our own skin can sense heat by a different method but we never developed a optical centrum for it. It's likely due to the properties of liquids found in our body.. water does not transmit infrared radiation in those wavelengths, but blocks it. Water has been a vital step into forming the eye - homogenously. The snakes sensors operate more like a pinhole camera. I am a thermal imaging enthusiast and for me that is one of the most interesting topics of biology.
that kinda reminds me of how they use antenna arrays and some crazy triangulation like inference to image a black hole. would that be a reasonable analogy?
@@andrewaronson3364 interferometry does work by combining wavelengths of a synthetic aperture. It can't be done in a body, so the analogy falls apart. It's more like yours ears. Where a a few sensors can give a full 'picture' because of the specific geometry and location between just two.
Fun fact: besides the iterative nature of evolution leading to all the weird and wonderful steps in a chemical reaction chain, another reason for the multiple steps is the activation energy required for each one. If the goal was to switch from molecule 1 straight to molecule 5, there isn't always enough energy available to raise into the new stable configuration, without more costly processes like raising the body temperature. Thanks for the video, you are master of describing complex topics in simple terms!
In many cases, the different elements in the signal transduction chain also have other uses as amplifiers or points where regulators can affect the signal. I don't know whether it's true for this specific one, but it's often the case in these kinds of signal transduction chains in a cell.
@@i9114 I don't know about him, but I do think. Evolution makes sense even if we consider it a dumb luck. Think about it. Because dumb luck needs to be lucky, it took millions of years for our eyes to be like that, for millions of dumb mistakes to occur in our ancestors DNA that just so happen to make something just a little better. (But don't forget about the insane majority of mistakes that led to death and disease of individuals. Thats why we only see the lucky ones, the unlucky are dead). Also, because dumb luck is dumb, our eyes are flawfull. The biggest flaw: Our retina is inverted. The photoreceptors are at the back and not at the front of it. That makes so that the light has to pass trough a layer of tissue, scattering it, and making our vision an inaccurate depiction of the light that enters our eyes. This is also why we have a blind spot. The nerves that come out of these cells need to turn around and go through a hole (the blind spot) in the retina to get to the brain. There are a lot of other problems. You should search about the origins of the human eye and also about its flaws, it is really interesting and I think that it makes much, much sense. Evolution is pretty half-assed if you think about it, you just have to give it some time to take something out of it... like... "millions of years" time... but the result is great... I mean.... it works... sometimes
The most amazing part of all this is that everything explained here happens in a matter of milliseconds, and has probably repeated something like millions of times while I was watching this. Being pretty much flawless, at least not in ways I can perceive. In moments like this that my awe for evolution is the greatest. Thanks Steve, I love what you do.
I'm pretty sure none of these processes come even close to flawless, it's all in just how robust to these aberrations the entire systems we're made up of are
@@AsmageddonPrince yeah, I know there's guaranteed degeneration through time, it's a given since no process is perfect. However I think it's impressive for this system to last 10 minutes, or years with little to no perceiving of flaws. Sometimes it's amazing to imagine how someone can live for years without even noticing that their body could be tearing apart from malfunction. This extremely complex and not pre designed system is way more resilient than I can ever imagine.
@@metametodo Believe me, it is't evolution. Self assembling atoms can not account for the ability to see or to have vision.This is a deliberate act of design. Evolution can not make atoms, self assemble, into living systems.
Hey there Mr. Mould. Nice vid! So, uh... I don't know how to break it to you so I'll just go ahead and say it... I think your studio is haunted. yep like with ghosts and the like
Hey Steve Great Video! We learned all of this in Medical school and the crazy thing is that in the retina not only the detection of light but also the processing of this information happen. You have different Horizontal cells which become activated by the photoreceptor cells and inhibit surrounding photoreceptor cells to create contrast. That is for example why dark areas seem on the edge to white areas much darker than being surrounded by dark areas. Fun fact: Most of the Proteins you have mentioned are reused by the body in different locations. cGMP in the nose and tongue for senses. Transducin which belongs to the family of G-Proteins are used in the Sympathicus(fight and flight) to increase your heart rate, constrict your Arteries,...
@@h7opolo not to be rude, but are you hearing impaired by chance? i am, so lip reading is kind of important to me. I missed the mistake you caught though, and I forgive Steve.
I'm guessing (as I have no knowledge of biology) that your brain wouldn't mind active low signals, it's like that 'you'll never know if other people experience color the same way' thing, so I wonder if it'd actually work if we simply removed the not gates or if they have some more important functionality as well.
Had the same thought. N then had a small bout of horror when it expanded to a 7 step process. Active low, invert, bit of a byte swap to get your pixel map, endian swap for dsp, dsp, nor matrix with some other channels, endian swap for interpreter, slice stream to fill framebuffer. Its a heck of a kludge, but does seem to work pretty good. (Just a fantasy imagery of whats goin on, ive no idea. But sounds about right) Makes my brain hurt.
Now consider conditional Boolean Math? Not not? Not how much not to not?? Minsky was a good go-to-guy about the topology of Boolean functions - specially in the realm of network adaptation. Fun stuff! He smashed neural net ideology by proving that NN cannot do exclusive or .. that was a breakthrough, but things developed from that . you can get Exor with enough topological layers - and specially when there is channel suppression from a feedback .. (complex back-prop) Last time I saw Minsky .. he was hiding his modular cognitive model to talk about how shaking-hands killed more people than guns. We are entering a time where the science of context becomes important. We will ultimately learn the absolute limits of atomic molecular switching - the blind-spot of the atom. But .. quantum reality shows a way forward. A Way that we have barely set foot upon, and learned that human feet are not good for this path? Think on that brother? Your insight will be valuable.
This is one of your better videos. You managed to cram a great deal of one semester of biochemistry and physiology into little over 10 minutes, and it's still informative and not complicated. Excellent work, Steve.
Hi Steve! Very nice video, as always. Just a little precision concerning what you explained around 11:31, the colour matching functions x(λ), y(λ), z(λ) are representations of the chromatic response of the observer, they don't exactly correspond to an amount of blue, green and red light. Thanks for all your work !
You playing around with the molecule gave me a new intuitive understanding of how molecules work I never grasped before. Like how they reach stable shapes due to how the forces attract and repel each other and then how outside energy can force them to switch into a new shape. Thanks!
re - 6:45 Neuronal action potentials are freakin' AMAZING!!! I love the way a signal is propagated without any loss of signal strength!! I mean, the way we use conductors to carry/ convey/ transmit a charge is always going to result in some loss, due to the resistance of the conductor. While you can work around these shortcomings by increasing the current, etc, natural selection found a much more elegant solution via action potentials. I say "elegant," because it's not especially simple, but it's not impossibly complex, either. It's not an especially efficient method of propagating a signal/ charge, but it IS wonderfully ingenious. It's the kind of solution that a thinking agent would never think of but the kind of thing that natural selection would naturally select.
A good argument against 'irreducible' complexity is that we should absolutely expect extremely intricate multi -step processes to be the norm with evolution by natural selection
Thank you for explaining this Steve!! It's seems soooo fragile, the way so many things are so dependent on one another and how each little thing seems so subtle. Considering all the processes that has to take place, the little molecules that need to move about in the fluid to the time it takes for the sodium charge to build up, I'm impressed at how quickly we can perceive movements and changes in our vision.
Love the videos Steve. Great explanations of how we see colour. Could we have a video on why we don't see colour at low light levels even though the same mechanism is being used? Many thanks for all the effort you put in.
Well yes, but this biochemistry is the first step and the brain won't get anything faster than this step allows. It uses various processing tricks to fill the gaps somehow, but this can't be done forever. ;)
Great video! Just to let you know, the conversion of the 11-cis-Retinal to 11-trans-Retinal actually involves what is known as a photo-catalyzed isomerization of one of the double bonds. This conversion of the molecule from the cis to the trans form is basically caused by the excitation of a set of molecular orbitals with visible light. This excitation rearranges the configuration of that bond so that it can act as a switch. You were mentioning the effects of slight conformational changes within the single bonds of the molecule as causing the change in the shape of the molecule. While this still does occur because of the relatively free nature of single bonds, this is not the reason for the conversion of the molecule from one form to another (in that case any long hydrocarbon would do the same job as 11-cis-Retinal, which we know is not the case!). In order to demonstrate that, you would actually have to remove one side of the molecule to show how the light actually causes a 'permanent', albeit temporary, chemical change from the cis to the trans form. I just thought this might be a useful detail to mention!
I noticed the single bonds were used to represent double bonds (just to clear up any confusion). It's just interesting to note that the cis and trans Retinal actually adopt fairly rigid conformations when not being catalyzed by light (this is what leads to its great ability to act like a 'switch'.
Kind of. Kind of not. Red/Green colour blindness isn't the only possible type; there are others. (Every combination you can think of in fact). It's just that Red/Green is the most common - and yes, that's because of how close together they are. Colour blindness is generally caused by a defect in one or more cones. This either means one of the cone types is less sensitive to light than it should be, is missing entirely, or has a defective protein that doesn't do it's job properly. All of these have the effect of rendering one part of the colour range non-functional, or near enough to it. People with one of their cones entirely missing/defective, can no longer distinguish that range, which means any colour that depends on being able to tell the difference between two overlapping ranges is now impossible. With a partial defect you can still tell these colours apart, but it's much more difficult. The reason Red/Green blindness is so common is because the molecules that produce those two cone types are very similar, so it takes only a minor change to effectively 'remove' one or the other. Plus, the name is actually ambiguous; given how the basic tests work, both having your 'green' cone and your 'red' cone missing lead to red/green colour blindness; They don't have the same exact effect, but it's still broadly a problem identifying red/green. Only having a defective/missing 'blue' cone causes a notably different result.
I’m amazed that this entire process is happening thousands of times per second in every single cone cell. It gives you an idea of how fast molecular interactions can be. Like your brain can visually detect something within about 100 milliseconds. That’s fast for all this plus the processing to happen!
What a great video! I loved seeing Steve get excited about some of the complexities of the eye’s innerworkings; it’s called “awe”. At 11:49 he states that this whole process could be simplified but “nature doesn’t work like that, evolution can’t overhaul.”, perhaps a need to find some flaw in the design we’ve just witnessed maybe as a way of looking for reassurance that this entire process was able to self-become. (Side note: There almost always seems to be a reason for things like these steps which appeared to be extra at first glance, we just might not understand it yet, so I was delighted to read jules1342’s comment for the answer.) For me, design = designer; I’m just not able to see the world in any other way. I love finding videos like this, and I’m so grateful people take the time to make them. As our science is getting better all the time, we get to learn a little more about our unbelievable world.
5:23 - 7:37 So, if I'm understanding correctly, when you look at a light, retinal molecules change shape which puts a force and changes the opsin protein harboring them. This shape change causes the protein to lose its transducin and causes a cascading molecular chain reaction that transforms cGMP [Sodium channel] molecules in the cell membrane into GMP, which is closed. This closure means sodium is no longer flowing in the cell, concentration goes down, and action potential is no longer present. This turns on the bipolar [NOT gate] cell and causes a signal to be interpreted. If all my understanding is valid, then I got questions: 1. Why can we see negative afterimages? Is it because of the change in sodium levels? Or is it just a unrelated event? 2. How do the cycle reset? Does the retinal molecule turn back? Does the opsin molecule get its transducin back? Does the GMP ever become cGMP again? Or is all this a one time change that is replace and not reset?
a-ma-zing video , absolutely loved it! so clearly explained, not too slow, not too fast, not too simplified, included everything i wanted to know, thank you!
8:36 I like how that small additional peak on the red on the left allows us to see violet even though we don't have anything that can pick up that light.
Absolutely brilliant! I am a high school student and these videos are a great pass time as well as educational for me. They are extremely informative and beautifully made. Thank you so much, and keep uploading these kinds of videos. I hope many more students turn to UA-cam to access amazing educational content such as yours.
Kudos to you for making good use of your time while in school. It will help you get further ahead in life later on. Whereas watching booty shakers on tic thot will rot your brain.
I would watch an entire channel of videos just of Steve Mould as a sheet ghost explaining science. I never thought about molecules fixing themselves into different shapes like that. I always just imagined them jiggling around but generally keeping the same form. I love that. Thanks for the upload!
I loved these 2 videos. I still have a few questions. Where exactly is the 'signal' and what is the mechanism generating the signal. Would it be possible to tap into the optic nerve fibers and read the signal electronically? How about generating the same signal for someone who is blind but still might have an optic nerve? Could you induce vision or even color?
Ok, so: The doorman stops working, things get turned on and there's potential for action. At some point something might be coming in your eyes. Got it, cheers Steve!
i love how this video is the same vibe of asking a drunk scientist at a bar a simple question and he just go on this adventure about something he's super excited about.
I learned all this as an undergrad in psychology and now I am really excited to see this again after reading a paper on visual perception. It's nice and fascinating too see how complex our world is and the moment I think I get bored of a topic there are new things to learn and a deeper understanding to obtain. Thanks steve :)
6:58 As far as I konw it's the other way around- normally if Na+ canals open- this leads to action potential spike and building resting potential (stand by mode) requires Na+ canals to be closed. So either Steve confused this and cGMP keeps canals closed or cGMP is opening canals but transformation of rodopsin leads to production of cGMP nor to lysis or it is different in retina cells then in all neurons and musculus and even euglena viridis.
Steve, are you waiting for me to turn on my pc? I see every upload you make in its first five minutes of being out. Crazy. Can't wait to watch this one
I literally just watched my med school lecture on this. Your video is way more fun and I even noticed that I wasn't pulling my hair out while watching it!
I just took a physiology exam which included the sensory system and I gained more knowledge about the eye in this video than I did through an entire university lecture
There are gifted teachers, and there are gifted academics. At universities, most professors and grad assistants are in the latter category, and made to do the job of the former whether they’re good at it or not. It’s one of the reasons people like Richard Feynman and Carl Sagan are such legends, because they were world class in both.
I'm a student at BYU, I know the professor who designed that bi-stable switch, Dr. Brian Jensen. He taught a kinematics class I took, but he does a bunch of cool stuff with MEMS.
@3:14 It is that the Photon has enough energy. The energy of a photon is defined by planks constant E=hf, so the energy of the photon is directly related to the frequency, the higher the frequency the more energy.
Hi Steve, I really enjoyed the video - thanks! One little quibble about sodium ions "flooding" into the cell... Action potentials can happen with relatively tiny movements of sodium and insignificant changes in intracellular ion concentration. If the ionic gradient was dissipated by a single action potential, you'd have to pump all the sodium ions that entered out again before another action potential would be possible. That would be like a single flash of a flashlight/torch running its battery down. However, excitable cells like neurons can typically fire off many APs before the loss of Na ion gradient becomes a problem. Eventually the cell's 'battery' will run down, and that's why you need a pump to remove the sodium and keep the battery charged - but if you knock out the pump, the cells can still generate APs (for a while).
Honestly, even when it's occasionally a topic I'm not particularly interested in(not the case in this video), your enthusiasm about it makes the video interesting anyway.
I'm a cardiologist. I've learned all this in MBBS but it was really nice to see it from a physics and chemistry perspective. Steve I've been subscribed to you for 500,000,000 years now.
That was quite simply excellent! The CGI on the proteins really gelled with me ( _Dr Who fanboy!_ ). You really do have some next-level comedy timing, like the arm being lopped off ( _reminded me of Monty Python's Holy Grail_ ). And THEN, after all that entertainment you give me some wicked science that I absolutely did not know. Retinal, bi-stable molecules, protein bond deformation. Steve, you are nailing this. Well done, chap.
The most incredible thing i find in how neurons work - is that how quickly they do it. Like, they have to pass actual molecules thrugh gaps between eachother and the retrieve them, and yet the do it so quickly, that it enables us to think and react with almost no delay Imagine running a factory, where all messaging (between humans and conveyors) is done by throwing capsules with whatever you need to send between people and buildings
11:06 I think you are oversimplifying this. In order to show a color you want to stimulate the three kinds of cells in the proportion you showed, but using combination of a number of other colors (most often tree but doesn't need to be). Unfortunately though you cannot just do it using a distinct color for each cell ("according to the amounts from the graph") , because their response is non-trivial and overlapping, e.g. you cant stimulate the "red" cell without stimulating the "green" one. You labeled them red, blue and green, but they are not pure red, blue and green sensors. There doesn't seem to be a color on that spectrum that can be solely "assigned" to one kind of sensor cell only. You want to figure out which combination of these complex stimuli responses to your base colors will be equivalent to the color you want to show. This doesn't look like a trivial problem to me, given the response curves. Mathematically speaking this reminds me of finding an orthogonal base in the color stimuli space (your base colors) and performing a change into that base from the one based on cellular response. Apparently Red, Green and Blue are close to being that orthogonal base.
@misium Well that's why you have the color matching functions. They're not responses from the cones; they come from experimental results of combining distinct colors to produce a particular perception. That's enough to produce your orthogonal basis I'm pretty sure. You don't have to worry about the cross over in the cones because it's not based on the cone response, it's based on perception. You just figure out what cone response combination corresponds to that perception. I think that's good enough.
This guy and his channel is quite amazing. He does really thorough research and has so much knowledge and find really creative ways to convey it in such an easily understandable way. All of it at a practically nonexistent budget from what I can see. I find it humorous how this awesome information is presented in such a "cheap" way. This guy deserves a bigger budget for better experiments and showcases along with better/professional production quality overall.
When I was working in computer graphics - this was exactly the reason why many color models (e.g for image compression) don't work with RGB, but models that better correspond to HVS, like YCbCr - where Y is brightness and Cb and Cr are "cone responses" are not that much important as we have much better resolution for change in brightness than in colour. This is exploited in JPEG image compression, for example. When working with colour, this is why systems like CIE Lab are more favourable - because unlike with RGB - change in L, a, b parameters correspond to the visual change of the colour. In RGB, we perceive much bigger change in colour when you change just G but much less change when you change just B, even if it is about the same amout.
My eyes were perfect when I had diabetes and after changing my diet specifically removing sodium nitrate my glucose levels dropped from a 20 to a 3.2. About 2 years later I needed glasses. Shortly after no glasses would work anymore and all the colors were different shades of grey. My eyes were really bad until I began drinking pops and energy drinks to bring my glucose levels up again. Slowly my eyes improved and about 2.5 years later my eyes came back and the I could see color again and was able to read again without glasses. I hope this helped and great video as usual.
You comment on how it is fascinating that there are often so many steps in going from one biochemical state to another. Like in reverting the retinal back to its' unbleached state (11:36). The steps to "re-sensitize" a rhodopsin molecule take a tremendous amount of time (like 30 minutes!). I have trouble imaging how/why it can possibly take that long! But, then, the fact that it does take that long may be evolutionarily intentional; the experience of going from a dim environment to a bright environment can include momentary blindness (or close to it), so having a large percentage of your rhodopsin not able to respond may be a good thing in a bright environment.
Kinda reminds me of computer memory. Like the different equilibrium states are like bits, those different proteins are like bytes, and so on. The different configurations creating our perception of sight, like how the all the different configurations of binary may create a display/UI of a computer
Yes! I should have made that clear. I wanted to get across the point that you don't just need *enough* energy, otherwise it would absorb every photon above a certain energy and not tail off into higher energies.
@@SteveMould I honestly did not understand what you were meaning. Now I understand your pedagogical "dilemma". Thanks for your rapid response. Overall a good explanation of vision.
@@christernyqvist3116 honestly, I appreciate comments like this. It helps me to hone my explaining skills! So long as they are polite like yours! They aren't always :)
This Halloween, I am going to dress up as a retina protein.
lol no you won't
@@jesse4202 it’s a joke
I thought the green was the scariest
It's like this fragment of "The Little Prince" when he draws an elephant in a snake and adults say it's a hat. You can put white sheet and when people say "Oh, you dressed as a ghost" you'll say: "Wrong, it's retina protein" :D
I bet nobody saw that coming
Your explanations are so amazing! In almost every single one of your videos, you express a concept that isn't explained all that often in a simple, humorous, and surprisingly informative fashion. There is no unnecessary simplification, it follows the science beautifully, and everything is put together just right. This channel is one of my favorites on all of UA-cam and I never hesitate to share your new videos after watching them. I hope you go right to the very top.
Well said, I second that!
Well, there's always simplification. For example, why does light cause the molecule to switch from cis to trans? It has to do with a radical mechanism of isomerization. Why does the molecule's shape and its interaction with proteins change the frequencies it absorbs? That has to do with the wavefunction of the electrons and delocalization/resonance. I think Steve is really good at choosing precisely the right things to leave out to tell a coherent story, and that makes him a very good educator. He'll rise to the same prominence as Veritasium or VSauce if UA-cam let him.
@@TomatoBreadOrgasm doesn't "no unnecessary simplification" and "leaves out just the right things".. mean the same thing?
@@kaitlyn__L I suppose it does. 🙃
@@TomatoBreadOrgasm This is the most civilized resolution of any youtube comment I've ever read ever. Nice work everyone.
i want colorful ghosts to hold me as sweetly as they held those molecules :(
Boo
Boo you
:(
In the shape of Patrick Swayze?
There's a simulation software avalable for the experience.... It's called Pacman.
There are some snakes that got heat vision. They got cells that work similar to a microbolometer pixel below their noses. It's just 6 pixels but the anatomy allows them to combine the signal greatly and locate something to eat in the darkness. It's likely responsive to 6-12micron wavelengths. Which almost fit into LWIR thermal cameras.
There is a great paper with low of images that show a modified therma imaging camera to represent what said snake and "see". It's a difficult evolutionary questions because our own skin can sense heat by a different method but we never developed a optical centrum for it. It's likely due to the properties of liquids found in our body.. water does not transmit infrared radiation in those wavelengths, but blocks it. Water has been a vital step into forming the eye - homogenously.
The snakes sensors operate more like a pinhole camera.
I am a thermal imaging enthusiast and for me that is one of the most interesting topics of biology.
Interesting indeed, thanks
that kinda reminds me of how they use antenna arrays and some crazy triangulation like inference to image a black hole. would that be a reasonable analogy?
@@andrewaronson3364 interferometry does work by combining wavelengths of a synthetic aperture. It can't be done in a body, so the analogy falls apart.
It's more like yours ears. Where a a few sensors can give a full 'picture' because of the specific geometry and location between just two.
Pits: eye's without lenses.
Oh I'd love to have a video about that!
Fun fact: besides the iterative nature of evolution leading to all the weird and wonderful steps in a chemical reaction chain, another reason for the multiple steps is the activation energy required for each one. If the goal was to switch from molecule 1 straight to molecule 5, there isn't always enough energy available to raise into the new stable configuration, without more costly processes like raising the body temperature.
Thanks for the video, you are master of describing complex topics in simple terms!
Isn't that also why the electron transport chains are so long?
Yes. you get "it" Kudos! Please consider the mechanics that supports "adaptive switching? And dare I name it? Local minima?
In many cases, the different elements in the signal transduction chain also have other uses as amplifiers or points where regulators can affect the signal. I don't know whether it's true for this specific one, but it's often the case in these kinds of signal transduction chains in a cell.
Evolution? So you think ‘blind’ dumb luck figured this all out?
@@i9114 I don't know about him, but I do think. Evolution makes sense even if we consider it a dumb luck. Think about it. Because dumb luck needs to be lucky, it took millions of years for our eyes to be like that, for millions of dumb mistakes to occur in our ancestors DNA that just so happen to make something just a little better. (But don't forget about the insane majority of mistakes that led to death and disease of individuals. Thats why we only see the lucky ones, the unlucky are dead). Also, because dumb luck is dumb, our eyes are flawfull. The biggest flaw: Our retina is inverted. The photoreceptors are at the back and not at the front of it. That makes so that the light has to pass trough a layer of tissue, scattering it, and making our vision an inaccurate depiction of the light that enters our eyes. This is also why we have a blind spot. The nerves that come out of these cells need to turn around and go through a hole (the blind spot) in the retina to get to the brain. There are a lot of other problems. You should search about the origins of the human eye and also about its flaws, it is really interesting and I think that it makes much, much sense. Evolution is pretty half-assed if you think about it, you just have to give it some time to take something out of it... like... "millions of years" time... but the result is great... I mean.... it works... sometimes
The most amazing part of all this is that everything explained here happens in a matter of milliseconds, and has probably repeated something like millions of times while I was watching this. Being pretty much flawless, at least not in ways I can perceive.
In moments like this that my awe for evolution is the greatest.
Thanks Steve, I love what you do.
the question is: can I connect it to my arduino?
@@D4no00 the future probably can be described by neuronal arduinos. Ask Elon musk.
I'm pretty sure none of these processes come even close to flawless, it's all in just how robust to these aberrations the entire systems we're made up of are
@@AsmageddonPrince yeah, I know there's guaranteed degeneration through time, it's a given since no process is perfect. However I think it's impressive for this system to last 10 minutes, or years with little to no perceiving of flaws.
Sometimes it's amazing to imagine how someone can live for years without even noticing that their body could be tearing apart from malfunction.
This extremely complex and not pre designed system is way more resilient than I can ever imagine.
@@metametodo Believe me, it is't evolution. Self assembling atoms can not account for the ability to see or to have vision.This is a deliberate act of design. Evolution can not make atoms, self assemble, into living systems.
Hey there Mr. Mould. Nice vid!
So, uh... I don't know how to break it to you so I'll just go ahead and say it...
I think your studio is haunted. yep like with ghosts and the like
Believing is seeing.
EXPLAIN???? Vot does this "haunted" word mean Hmmmmmmmmmmmmmmmm? Vot sciencery is this?
And by colorful ghosts at that. Reminds me of Pacman...
Arm choppers to boot!
Hey Steve Great Video! We learned all of this in Medical school and the crazy thing is that in the retina not only the detection of light but also the processing of this information happen. You have different Horizontal cells which become activated by the photoreceptor cells and inhibit surrounding photoreceptor cells to create contrast. That is for example why dark areas seem on the edge to white areas much darker than being surrounded by dark areas. Fun fact: Most of the Proteins you have mentioned are reused by the body in different locations. cGMP in the nose and tongue for senses. Transducin which belongs to the family of G-Proteins are used in the Sympathicus(fight and flight) to increase your heart rate, constrict your Arteries,...
8:38 voice dubbed over mistakenly saying the word "pixels".
Damn, you noticed!
@@SteveMould much to your credit, it's cuz I hung on every word you said. I can't audibly detect the dub, but my lip reading is compulsive.
@@h7opolo
not to be rude, but are you hearing impaired by chance? i am, so lip reading is kind of important to me. I missed the mistake you caught though, and I forgive Steve.
@@holdmybeer i naively wish for hearing impairment as I am overly sensitive [to sound].
How is it even possible to notice something like this "compulsively"? I admire this talent!
Psychotherapist: Ghost Steve Mould isn't real, he can't hurt you with chemistry!
Ghost Steve Mould holding a scary molecule: 4:09
The retinal-ghosts did it for me.
Great video! And amazing of you to use 4k50p, very much appreciated.
EDIT: omg that door sequence
The high budget illustrations in this video are really top notch.
The sheet molecules had me on the floor lmao
7:07 the computer nerd inside me immediately thinks: so they are "active low"? :D
Edit: I appreciate the "not gate"
I'm guessing (as I have no knowledge of biology) that your brain wouldn't mind active low signals, it's like that 'you'll never know if other people experience color the same way' thing, so I wonder if it'd actually work if we simply removed the not gates or if they have some more important functionality as well.
Had the same thought. N then had a small bout of horror when it expanded to a 7 step process. Active low, invert, bit of a byte swap to get your pixel map, endian swap for dsp, dsp, nor matrix with some other channels, endian swap for interpreter, slice stream to fill framebuffer. Its a heck of a kludge, but does seem to work pretty good.
(Just a fantasy imagery of whats goin on, ive no idea. But sounds about right) Makes my brain hurt.
Especially at the genetic level, gene interaction networks are often thought of as analogous to circuit diagrams
@@Huntracony Imagine removing the not gate right now, and seeing every color inverted.
Now consider conditional Boolean Math? Not not?
Not how much not to not??
Minsky was a good go-to-guy about the topology of Boolean functions - specially in the realm of network adaptation. Fun stuff! He smashed neural net ideology by proving that NN cannot do exclusive or .. that was a breakthrough, but things developed from that . you can get Exor with enough topological layers - and specially when there is channel suppression from a feedback .. (complex back-prop) Last time I saw Minsky .. he was hiding his modular cognitive model to talk about how shaking-hands killed more people than guns. We are entering a time where the science of context becomes important. We will ultimately learn the absolute limits of atomic molecular switching - the blind-spot of the atom. But .. quantum reality shows a way forward. A Way that we have barely set foot upon, and learned that human feet are not good for this path? Think on that brother? Your insight will be valuable.
Holy shit. I mean really, holy shit this is amazing. All this is going on right now in my eyes! Freaking NOT gates!?!
I'm not really an expert or anything, but I'm pretty sure it just works.
God demmit Todd
@@keonix506 or Jensen
🤣
I dunno, I've seen some pretty convincing illusions that suggest otherwise :P.
iVision
This is one of your better videos. You managed to cram a great deal of one semester of biochemistry and physiology into little over 10 minutes, and it's still informative and not complicated. Excellent work, Steve.
Big Chungus is so funny HAHAHAHAHA
6:34 the doorman loses an arm but gain weight around his belly. Interesting conservation of mass there
Francois Roewer-Despres Perfectly balanced, as all things should be
Felix the Sloth I understood that reference
Hi Steve! Very nice video, as always.
Just a little precision concerning what you explained around 11:31, the colour matching functions x(λ), y(λ), z(λ) are representations of the chromatic response of the observer, they don't exactly correspond to an amount of blue, green and red light.
Thanks for all your work !
You playing around with the molecule gave me a new intuitive understanding of how molecules work I never grasped before. Like how they reach stable shapes due to how the forces attract and repel each other and then how outside energy can force them to switch into a new shape. Thanks!
"Advertising and other nefarious things like that"
re - 6:45
Neuronal action potentials are freakin' AMAZING!!!
I love the way a signal is propagated without any loss of signal strength!! I mean, the way we use conductors to carry/ convey/ transmit a charge is always going to result in some loss, due to the resistance of the conductor. While you can work around these shortcomings by increasing the current, etc, natural selection found a much more elegant solution via action potentials. I say "elegant," because it's not especially simple, but it's not impossibly complex, either. It's not an especially efficient method of propagating a signal/ charge, but it IS wonderfully ingenious. It's the kind of solution that a thinking agent would never think of but the kind of thing that natural selection would naturally select.
Great video. Nice CGI effects with the white and orange sheets ;-)
Sheet-G-I effects?
I thought those were PacMan ghosts EATIN TEH DOTZ!
A good argument against 'irreducible' complexity is that we should absolutely expect extremely intricate multi -step processes to be the norm with evolution by natural selection
Thank you for explaining this Steve!! It's seems soooo fragile, the way so many things are so dependent on one another and how each little thing seems so subtle. Considering all the processes that has to take place, the little molecules that need to move about in the fluid to the time it takes for the sodium charge to build up, I'm impressed at how quickly we can perceive movements and changes in our vision.
Speed only makes sense within the framework created by these processes
I'm not going to lie the quality and consistency of this guys brain food is unparralled
I award him 3.14 Michelin Stars
Love the videos Steve. Great explanations of how we see colour. Could we have a video on why we don't see colour at low light levels even though the same mechanism is being used? Many thanks for all the effort you put in.
Very nice description!
"I'm always fascinated by how complicated biochemistry is" Yes, most things are more complex than originally perceived...
Must have missed this one. Cheers for the relink
Actually surprisingly uncomplicated? You have a fantastic talent at explaining things in a fascinating and intuitive manner.
Thanks for the recommendation to revisit this video! I don't think I was subbed when it was released
And this complicated biochemistry is the reason for why we perceive more than 20fps as movement.
I think that is more to do with the brain processing than the biochemistry of the eye
Ron Wesilen it's literally both
Well yes, but this biochemistry is the first step and the brain won't get anything faster than this step allows. It uses various processing tricks to fill the gaps somehow, but this can't be done forever. ;)
Great video! Just to let you know, the conversion of the 11-cis-Retinal to 11-trans-Retinal actually involves what is known as a photo-catalyzed isomerization of one of the double bonds. This conversion of the molecule from the cis to the trans form is basically caused by the excitation of a set of molecular orbitals with visible light. This excitation rearranges the configuration of that bond so that it can act as a switch. You were mentioning the effects of slight conformational changes within the single bonds of the molecule as causing the change in the shape of the molecule. While this still does occur because of the relatively free nature of single bonds, this is not the reason for the conversion of the molecule from one form to another (in that case any long hydrocarbon would do the same job as 11-cis-Retinal, which we know is not the case!). In order to demonstrate that, you would actually have to remove one side of the molecule to show how the light actually causes a 'permanent', albeit temporary, chemical change from the cis to the trans form. I just thought this might be a useful detail to mention!
I noticed the single bonds were used to represent double bonds (just to clear up any confusion). It's just interesting to note that the cis and trans Retinal actually adopt fairly rigid conformations when not being catalyzed by light (this is what leads to its great ability to act like a 'switch'.
That was one of my most searched videos since like 3 years... Thank you so much! you helped me a lot
Wow, a single molecule made an entire Avenger?
Heh
Sometimes your videos go beyond my capacity for absorption capacity/comprehension, but I stay til the end because you are such an excellent presenter!
So is the red/green overlap also part of the reason red-green colourblindness is a thing?
Kind of. Kind of not.
Red/Green colour blindness isn't the only possible type; there are others. (Every combination you can think of in fact).
It's just that Red/Green is the most common - and yes, that's because of how close together they are.
Colour blindness is generally caused by a defect in one or more cones.
This either means one of the cone types is less sensitive to light than it should be, is missing entirely, or has a defective protein that doesn't do it's job properly.
All of these have the effect of rendering one part of the colour range non-functional, or near enough to it.
People with one of their cones entirely missing/defective, can no longer distinguish that range, which means any colour that depends on being able to tell the difference between two overlapping ranges is now impossible.
With a partial defect you can still tell these colours apart, but it's much more difficult.
The reason Red/Green blindness is so common is because the molecules that produce those two cone types are very similar, so it takes only a minor change to effectively 'remove' one or the other.
Plus, the name is actually ambiguous; given how the basic tests work, both having your 'green' cone and your 'red' cone missing lead to red/green colour blindness;
They don't have the same exact effect, but it's still broadly a problem identifying red/green.
Only having a defective/missing 'blue' cone causes a notably different result.
I’m amazed that this entire process is happening thousands of times per second in every single cone cell. It gives you an idea of how fast molecular interactions can be. Like your brain can visually detect something within about 100 milliseconds. That’s fast for all this plus the processing to happen!
This blew my mind, you made such an awesome and complicated phenomenon so accessible and captivating. Thanks for the awesome video!
What a great video! I loved seeing Steve get excited about some of the complexities of the eye’s innerworkings; it’s called “awe”. At 11:49 he states that this whole process could be simplified but “nature doesn’t work like that, evolution can’t overhaul.”, perhaps a need to find some flaw in the design we’ve just witnessed maybe as a way of looking for reassurance that this entire process was able to self-become. (Side note: There almost always seems to be a reason for things like these steps which appeared to be extra at first glance, we just might not understand it yet, so I was delighted to read jules1342’s comment for the answer.) For me, design = designer; I’m just not able to see the world in any other way. I love finding videos like this, and I’m so grateful people take the time to make them. As our science is getting better all the time, we get to learn a little more about our unbelievable world.
The second smaller peak for the red/long spectrum is at double the frequency of the larger peak.
a harmonic?
@@majacovic5141 Precisely!
@@gsurfer04 😁
You make me feel I have been robbed by medical school. Seriously, this world needs a lot more conceptual teachers like you than it currently has!!!
I love how you explain things..
Just when I was getting confused, a colorful ghost shows up 😂
5:23 - 7:37 So, if I'm understanding correctly, when you look at a light, retinal molecules change shape which puts a force and changes the opsin protein harboring them. This shape change causes the protein to lose its transducin and causes a cascading molecular chain reaction that transforms cGMP [Sodium channel] molecules in the cell membrane into GMP, which is closed. This closure means sodium is no longer flowing in the cell, concentration goes down, and action potential is no longer present. This turns on the bipolar [NOT gate] cell and causes a signal to be interpreted.
If all my understanding is valid, then I got questions:
1. Why can we see negative afterimages? Is it because of the change in sodium levels? Or is it just a unrelated event?
2. How do the cycle reset? Does the retinal molecule turn back? Does the opsin molecule get its transducin back? Does the GMP ever become cGMP again? Or is all this a one time change that is replace and not reset?
Thank you Steve very cool, this is enlightening
a-ma-zing video , absolutely loved it! so clearly explained, not too slow, not too fast, not too simplified, included everything i wanted to know, thank you!
Steve Mould leather jacket ASMR video when? (Joking aside, super great video!)
So elegantly simple, yet so amazingly complicated.
Love your videos.
This is amazing, a brilliant way to explain something really complicated in an easy to consume and funny way 👍
8:36 I like how that small additional peak on the red on the left allows us to see violet even though we don't have anything that can pick up that light.
Mom : retinol ghost is not real, it can't haunt you
4:20 : 😣
Another interesting and enlightening video. Glad we have creators like you :)
Love the Greaser look. Great content too!
The sheets moving the molecules was genius xo great content, as per
Absolutely brilliant! I am a high school student and these videos are a great pass time as well as educational for me. They are extremely informative and beautifully made. Thank you so much, and keep uploading these kinds of videos. I hope many more students turn to UA-cam to access amazing educational content such as yours.
Kudos to you for making good use of your time while in school. It will help you get further ahead in life later on. Whereas watching booty shakers on tic thot will rot your brain.
I would watch an entire channel of videos just of Steve Mould as a sheet ghost explaining science. I never thought about molecules fixing themselves into different shapes like that. I always just imagined them jiggling around but generally keeping the same form. I love that. Thanks for the upload!
5:40 "Spooky action at no distance" ;-) Einstein approves :-P
Helpful information
I loved these 2 videos. I still have a few questions. Where exactly is the 'signal' and what is the mechanism generating the signal. Would it be possible to tap into the optic nerve fibers and read the signal electronically? How about generating the same signal for someone who is blind but still might have an optic nerve? Could you induce vision or even color?
So "Love at first sight", "Chemistry between us", and other phrases, are actually spot on.
Well that's my Halloween costume sorted then.
Ok, so: The doorman stops working, things get turned on and there's potential for action. At some point something might be coming in your eyes. Got it, cheers Steve!
holy shit im early, awesome video!
i love how this video is the same vibe of asking a drunk scientist at a bar a simple question and he just go on this adventure about something he's super excited about.
I know how my mum feels when I talk about science now.
Kid ambles into garage: "What's daddy doing?"
You're going as a ghost this Halloween, aren't you.
I learned all this as an undergrad in psychology and now I am really excited to see this again after reading a paper on visual perception. It's nice and fascinating too see how complex our world is and the moment I think I get bored of a topic there are new things to learn and a deeper understanding to obtain.
Thanks steve :)
4:09 God damnit Steve put a warning next time. You scared the shit out of me!
6:58 As far as I konw it's the other way around- normally if Na+ canals open- this leads to action potential spike and building resting potential (stand by mode) requires Na+ canals to be closed. So either Steve confused this and cGMP keeps canals closed or cGMP is opening canals but transformation of rodopsin leads to production of cGMP nor to lysis or it is different in retina cells then in all neurons and musculus and even euglena viridis.
Steve, are you waiting for me to turn on my pc? I see every upload you make in its first five minutes of being out. Crazy.
Can't wait to watch this one
That or you turn your computer on (and off) every 5 minutes
I literally just watched my med school lecture on this.
Your video is way more fun and I even noticed that I wasn't pulling my hair out while watching it!
I just took a physiology exam which included the sensory system and I gained more knowledge about the eye in this video than I did through an entire university lecture
There are gifted teachers, and there are gifted academics. At universities, most professors and grad assistants are in the latter category, and made to do the job of the former whether they’re good at it or not. It’s one of the reasons people like Richard Feynman and Carl Sagan are such legends, because they were world class in both.
I'm a student at BYU, I know the professor who designed that bi-stable switch, Dr. Brian Jensen. He taught a kinematics class I took, but he does a bunch of cool stuff with MEMS.
@3:14 It is that the Photon has enough energy. The energy of a photon is defined by planks constant E=hf, so the energy of the photon is directly related to the frequency, the higher the frequency the more energy.
Hi Steve, I really enjoyed the video - thanks! One little quibble about sodium ions "flooding" into the cell... Action potentials can happen with relatively tiny movements of sodium and insignificant changes in intracellular ion concentration. If the ionic gradient was dissipated by a single action potential, you'd have to pump all the sodium ions that entered out again before another action potential would be possible. That would be like a single flash of a flashlight/torch running its battery down. However, excitable cells like neurons can typically fire off many APs before the loss of Na ion gradient becomes a problem. Eventually the cell's 'battery' will run down, and that's why you need a pump to remove the sodium and keep the battery charged - but if you knock out the pump, the cells can still generate APs (for a while).
Honestly, even when it's occasionally a topic I'm not particularly interested in(not the case in this video), your enthusiasm about it makes the video interesting anyway.
I love the demonstration you used for this explanation
I'm a cardiologist. I've learned all this in MBBS but it was really nice to see it from a physics and chemistry perspective.
Steve I've been subscribed to you for 500,000,000 years now.
That was quite simply excellent! The CGI on the proteins really gelled with me ( _Dr Who fanboy!_ ). You really do have some next-level comedy timing, like the arm being lopped off ( _reminded me of Monty Python's Holy Grail_ ). And THEN, after all that entertainment you give me some wicked science that I absolutely did not know. Retinal, bi-stable molecules, protein bond deformation. Steve, you are nailing this. Well done, chap.
Glad youtube brought this back up. Great old school Steve video
The most incredible thing i find in how neurons work - is that how quickly they do it. Like, they have to pass actual molecules thrugh gaps between eachother and the retrieve them, and yet the do it so quickly, that it enables us to think and react with almost no delay
Imagine running a factory, where all messaging (between humans and conveyors) is done by throwing capsules with whatever you need to send between people and buildings
loving the greaser look, steve
Your content is the ideal primer for conversations we should be having today.
11:06 I think you are oversimplifying this. In order to show a color you want to stimulate the three kinds of cells in the proportion you showed, but using combination of a number of other colors (most often tree but doesn't need to be). Unfortunately though you cannot just do it using a distinct color for each cell ("according to the amounts from the graph") , because their response is non-trivial and overlapping, e.g. you cant stimulate the "red" cell without stimulating the "green" one. You labeled them red, blue and green, but they are not pure red, blue and green sensors. There doesn't seem to be a color on that spectrum that can be solely "assigned" to one kind of sensor cell only.
You want to figure out which combination of these complex stimuli responses to your base colors will be equivalent to the color you want to show. This doesn't look like a trivial problem to me, given the response curves.
Mathematically speaking this reminds me of finding an orthogonal base in the color stimuli space (your base colors) and performing a change into that base from the one based on cellular response. Apparently Red, Green and Blue are close to being that orthogonal base.
@misium Well that's why you have the color matching functions. They're not responses from the cones; they come from experimental results of combining distinct colors to produce a particular perception. That's enough to produce your orthogonal basis I'm pretty sure. You don't have to worry about the cross over in the cones because it's not based on the cone response, it's based on perception. You just figure out what cone response combination corresponds to that perception. I think that's good enough.
You really strike a good balance with your videos. Love your work, keep it up.
This guy and his channel is quite amazing. He does really thorough research and has so much knowledge and find really creative ways to convey it in such an easily understandable way. All of it at a practically nonexistent budget from what I can see. I find it humorous how this awesome information is presented in such a "cheap" way. This guy deserves a bigger budget for better experiments and showcases along with better/professional production quality overall.
When I was working in computer graphics - this was exactly the reason why many color models (e.g for image compression) don't work with RGB, but models that better correspond to HVS, like YCbCr - where Y is brightness and Cb and Cr are "cone responses" are not that much important as we have much better resolution for change in brightness than in colour. This is exploited in JPEG image compression, for example.
When working with colour, this is why systems like CIE Lab are more favourable - because unlike with RGB - change in L, a, b parameters correspond to the visual change of the colour. In RGB, we perceive much bigger change in colour when you change just G but much less change when you change just B, even if it is about the same amout.
My eyes were perfect when I had diabetes and after changing my diet specifically removing sodium nitrate my glucose levels dropped from a 20 to a 3.2. About 2 years later I needed glasses. Shortly after no glasses would work anymore and all the colors were different shades of grey. My eyes were really bad until I began drinking pops and energy drinks to bring my glucose levels up again. Slowly my eyes improved and about 2.5 years later my eyes came back and the I could see color again and was able to read again without glasses. I hope this helped and great video as usual.
The fact that you researched a concept this deep, gives me hope that science may survive the world we share with flat earthers
You comment on how it is fascinating that there are often so many steps in going from one biochemical state to another. Like in reverting the retinal back to its' unbleached state (11:36). The steps to "re-sensitize" a rhodopsin molecule take a tremendous amount of time (like 30 minutes!). I have trouble imaging how/why it can possibly take that long! But, then, the fact that it does take that long may be evolutionarily intentional; the experience of going from a dim environment to a bright environment can include momentary blindness (or close to it), so having a large percentage of your rhodopsin not able to respond may be a good thing in a bright environment.
Kinda reminds me of computer memory. Like the different equilibrium states are like bits, those different proteins are like bytes, and so on. The different configurations creating our perception of sight, like how the all the different configurations of binary may create a display/UI of a computer
Love the scientist biker look...
it's so surreal to think that all this diffusion and stuff happens fast enough for our brains to think it's instantaneous.
@@gregoryford2532 no i mean the chemical reactions in our eyes, do many things have to happen witinh a few milliseconds
This explanation made so much sense! Thanks! Just arrived from Smarter Every Day. You've definitely earned my subscription.
Looking quite dashing in this video Steve!
3:21 in the video; Frequency is proportional to energy, they are not independent quantities.
Yes! I should have made that clear. I wanted to get across the point that you don't just need *enough* energy, otherwise it would absorb every photon above a certain energy and not tail off into higher energies.
@@SteveMould I honestly did not understand what you were meaning. Now I understand your pedagogical "dilemma". Thanks for your rapid response. Overall a good explanation of vision.
By the way, do get a lot of nitpicking comments like mine? (I feel a bit ashamed now)
@@christernyqvist3116 honestly, I appreciate comments like this. It helps me to hone my explaining skills! So long as they are polite like yours! They aren't always :)
Gonna get a beer and watch it again :D Cheers mate! :) I liked the way you were holding the door haha
That was bloody fascinating... thank you, a great explanation of something we don't really think about often. That was great!