Vision Is Actually A Chemical Reaction
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How does vision work on the molecular level? It all starts with a molecule in your rod and cone cells called retinal that flips from one conformation to another when visible light photons hit it.
What follows is fascinating - the phototransduction cascade, that leads ultimately to neurons firing in your brain.
I mention my last video in this one. Here it is: • Why you can't take a g...
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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 TH-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 TH-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!
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.
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
Psychotherapist: Ghost Steve Mould isn't real, he can't hurt you with chemistry!
Ghost Steve Mould holding a scary molecule: 4:09
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!
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!
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.
The high budget illustrations in this video are really top notch.
"Advertising and other nefarious things like that"
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,...
Holy shit. I mean really, holy shit this is amazing. All this is going on right now in my eyes! Freaking NOT gates!?!
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
The retinal-ghosts did it for me.
Great video! And amazing of you to use 4k50p, very much appreciated.
EDIT: omg that door sequence
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
Great video. Nice CGI effects with the white and orange sheets ;-)
Sheet-G-I effects?
I thought those were PacMan ghosts EATIN TEH DOTZ!
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
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!
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
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.
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
So elegantly simple, yet so amazingly complicated.
Love your videos.
Another interesting and enlightening video. Glad we have creators like you :)
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. ;)
This blew my mind, you made such an awesome and complicated phenomenon so accessible and captivating. Thanks for the awesome video!
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!
You really strike a good balance with your videos. Love your work, keep it up.
I'm not going to lie the quality and consistency of this guys brain food is unparralled
I award him 3.14 Michelin Stars
Must have missed this one. Cheers for the relink
This explanation made so much sense! Thanks! Just arrived from Smarter Every Day. You've definitely earned my subscription.
I love the demonstration you used for this explanation
Thank you Steve very cool, this is enlightening
I love how you explain things..
Just when I was getting confused, a colorful ghost shows up 😂
Very nice description!
"I'm always fascinated by how complicated biochemistry is" Yes, most things are more complex than originally perceived...
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.
This is amazing, a brilliant way to explain something really complicated in an easy to consume and funny way 👍
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'.
I love how well you explain it man, thanks for this video keep it going!
Looking quite dashing in this video Steve!
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.
The second smaller peak for the red/long spectrum is at double the frequency of the larger peak.
a harmonic?
@@majacovic5141 Precisely!
@@gsurfer04 😁
The sheets moving the molecules was genius xo great content, as per
Steve, your videos are fantastic.
Love the Greaser look. Great content too!
5:40 "Spooky action at no distance" ;-) Einstein approves :-P
Love the compliant mechanism you got there.
Actually surprisingly uncomplicated? You have a fantastic talent at explaining things in a fascinating and intuitive manner.
Steve Mould leather jacket ASMR video when? (Joking aside, super great video!)
Thanks for the recommendation to revisit this video! I don't think I was subbed when it was released
This was so interesting! Thanks, Steve!
Glad youtube brought this back up. Great old school Steve video
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?
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 TH-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.
That was a lot to take in. You did a good job explaining it. Thanks 😁
You are incredible explaining things !
Glad I found this.
Like that scenes on blankets, funny
Well that's my Halloween costume sorted then.
Mom : retinol ghost is not real, it can't haunt you
4:20 : 😣
Fantastic, I'm glad you brought this to my attention. Thanks
Love the protein Ghost analogy. I really enjoy learning with your videos. Tks a lot!
holy shit im early, awesome video!
You're going as a ghost this Halloween, aren't you.
Such a good video. Really enjoyed this one.
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!
I know how my mum feels when I talk about science now.
This is so amazingly complex, thanks!
Great explanation. Love the high-budget visual aids, too!
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
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!
Been waiting for this video since the last one.
loving the greaser look, steve
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.
Another great video. Cheers for the share
Your illustrative visualisations in this video filled me with a ridiculous amount of joy, while still learning *so* much. Thank you #DayMade
fascinating video, absolutely fantastic. thank you and please keep doing what you are doing!!
Sometimes your videos go beyond my capacity for absorption capacity/comprehension, but I stay til the end because you are such an excellent presenter!
I love the videos you make
That you can only find in a textbook
This video is brilliant, enjoyed from start to end!
This was my favourite video of you wo far!
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!
simply illustrating how a molecule can be a microscopic switch blew my mind. the rest was just the cherry on top. amazing stuff.
I liked this video; it felt like Steve took it up a notch. Good stuff, well explained.
Beautiful! This makes so much sense!
Never heard of the majority of this - thanks for bringing new learning to us, in the best way!
Your content is the ideal primer for conversations we should be having today.
nice vid gonna have to repeat this for awhile
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!
Such a precious work this video, great job....!!!!!!!!
Awesome explanation.
Helpful information
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).
Awesome, as always.
Thanks love the chemistry lesson. We need more of this
Great video!