2-Minute Neuroscience: Phototransduction
Vložit
- čas přidán 10. 07. 2019
- Phototransduction is the process that occurs in the retina where light is converted into electrical signals that can be understood by the rest of the nervous system. In this video, I explain the mechanism underlying phototransduction in rod photoreceptor cells.
This process is a little complicated; I'd suggest at least having a good understanding of membrane potential before you try to grasp phototransduction. You can learn more about membrane potential in this video: • 2-Minute Neuroscience:...
TRANSCRIPT:
Welcome to 2 minute neuroscience, where I explain neuroscience topics in 2 minutes or less. In this installment I will discuss phototransduction.
Phototransduction is the process that occurs in the retina where light is converted into electrical signals that can be understood by the nervous system. It primarily takes place in photoreceptor cells, of which there are two main types: rods and cones. I will discuss phototransduction in rods, although the process is similar in cones.
In the dark, positively charged sodium ions flow into rod cells through ion channels that are activated by a substance called cyclic guanosine monophosphate, or cGMP. This influx of positively charged ions causes cells to remain in a depolarized state, leading to the continuous release of the neurotransmitter glutamate. Inside the rod cell there is a substance called rhodopsin, which is made up of a protein called opsin and a molecule called retinal, which is capable of absorbing light. When retinal absorbs light, its configuration changes, an event that prompts opsin to activate a protein called transducin. Transducin activates a type of enzyme known as a phosphodiesterase, which begins breaking down cGMP. As cGMP levels fall, the ion channels that are opened by cGMP begin to close. Thus, less sodium enters the cell and the cell becomes hyperpolarized due to potassium ions that regularly leave the cell. Consequently, glutamate release decreases. Strangely enough, this decrease in neurotransmitter release acts as a signal that a light stimulus is present. The rod cell returns to its normal state quickly when activated rhodopsin is inactivated, and a protein called arrestin subsequently binds to it. Arrestin blocks the ability of rhodopsin to activate transducin, which makes the cascade unable to continue. A complex process then restores retinal to its original configuration, making it ready to absorb light once again.
References:
Meister M, Tessier-Lavigne M. Low-Level Visual Processing: The Retina. In: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA, Hudspeth AJ, eds. Principles of Neural Science. 5th ed. New York: McGraw Hill; 2013.
Purves D, Augustine GJ, Fitzpatrick P, Hall WC, Lamantia AS, Mooney RD, Platt ML, White LE, eds. Neuroscience. 6th ed. New York: Sinauer Associates; 2018. - Věda a technologie
You explained my 50 min neuro lecture in 2 mins you’re the man!!!
so easily!!!
definitely a shit lecture then
Trueee
not u being scarily accurate
That's good.
I'm a current US medical student, and love your videos as previews for my lectures. Keep up the great work, and thank you!
👍👍😁
Hands dow, one of the best channels on CZcams. Whoever this guy is, he is incredible and deserves all the good things life can offer. Fucking legend.
Thank you!
COMPLETED A 50 MIN LEC VIDEO IN LESS THAN 2 MIN. HATSS OFFFFF
you put a transcript too, *cries a little* love u
Thanks for the video, I'm from Germany and I was looking for a video to explaim this topic in german, but didn't find a video that helped me to understand this. Yours did, tho, even tho I struggled with language a bit. Thanks and Greetings from Germany! :)
So comprehensive! Best video on internet today
STELLAR job explaining this concept--thank you so much!
This is fantastic! Thank you so much for sharing your knowledge this way. It’s bite sized, visual and I’m enjoying reading with the transcript.
You're welcome, thanks for watching!
Great video you explained in less than 2 minuts what would've taken me at least half an hour to understand
Great videos i'm around the 10 age area and using your videos to prepare for the brain bee. Your videos carried me through regional thanks to you I made it to nationals
That's awesome! Good luck at nationals! Let me know how you do!
exam in a few hours and this helped me so much thanks for that!
THIS IS AMAZING ! 👍 you just explained this topic in a few min
keep making vedios like this
this was really helpful thank you!
This helped me with my medical physics independent research!
it was hard to understand what was going on until i came across this video thank a ton dude
My teacher spent 1 hour to talk about this, and I still don't understand. I comprehended after you explained it within 2 min.
Crisp, concise,clarity wow🫡
Incredibly helpful video !!!! 😍🤓
Great video. Jazak'ALLAH. Thanks!
Words of encouragement.
Yeah, new video! Keep it up 👍❤
Thanks!
i saw transcript, had to subscribe
Thanks, enough and comphrensive :))
excellent!
Informative video 🔥😍
Talented teacher
Beauty revision
damn, that video made my day !
Thank you
Thank you so much
Great 🖤🖤
Thank you !!!!
Thank you sir
What about Intrinsically photosensitive retinal ganglion cell (ipRGC)? Is there any way you can make a video about that too or explain it to me?:) Great vid btw
perfect my G
Good for review, not first learning.
Very good
Could an anomaly somewhere in this process cause visual snow syndrome? Maybe the glutamate imbalance? Really wished someone who knew about this stuff would look into it :(
Hi pls answer: what kind of mutation (i.e. in which step) would lead to /light causing a depolarization/ in the rod?
What is the timescale for these processes? How fast can the retina respond to photons, then "Reset" ready to process new photons?
Great! Thank you! Do you know more about Phototransduction?
I know a bit more detail than what's included in the video, but it's certainly not my area of expertise. Did you have a specific question?
Thank gurujii
Is the opsin protein part of the transmembrane domain?
Thanks for the video... I have a question. How is the Sodium gradient established around photoreceptor cells? Are there Na channels which use energy to pump Na back out of the cell causing that constant flow in in the dark?
na K pump?
Looking forward to the long version of this.
Memory Formation and Retrieval
When it comes to education MEMORIZATION is a must !
What about S. P. Infusion of norepinephrine and it's carbon rings !
What is the combination behind it and carbon rings of serotonin ?
Every chemical compound has it's endemic rethum or wave generated according to varying ionization energy when excited , and so it's a matter of short circuit .
Mind is ,
How we react to signals from environment and it's the medium We recoganiz them.
So if environment is infused with the unsuitable , then
our surroundings would also be confused ?
I needed this 2 months ago ahahahaha
:) Sorry! I realized I needed a video on it when I was teaching it 2 months ago...
Ahaha I laughed.
Please put some practical examples on the description 🙏
Sir, how glutamate then evokes impulse
Such a complex process. What can go wrong?
Wow! All of that happens multiple times a second?
🐐❤
Id like to know how quickly a cycle of...
DETECTION > SEND SIGNAL > RESET
...happens. Because the way that this process is described amd then graphically illustrated within the explanation takes over a minute - whereas, in reality, hundreds of housands of photons must be colliding with the back of the retina every millisecond...!
How much is absorbed, how much is ignored, is the eye aware of the intensity and therefore demonstrate brightness artificially in the brain? Too many questions about the estimations of biological guesswork!
What's the difference between photoreception and phototransduction.. ?
So if I see light differently, then this process didn’t complete itself? I see more than the light itself …I am not a medical student or professional, I’m just curious looking to understand how my brain and ocular system processes light
سبحان الله اعظم الخالقين..
Woooow
what can make someone see red and green, suddenly much more vivid ?
How long does the cycle take?
I don't know exact numbers, but the process up to the inactivation of rhodopsin happens in a fraction of a second. I believe the full cycle (including restoring retinal to its original configuration) takes a bit longer, but still we'd be talking a few seconds or less.
Hmm.. it seems a bit slow. I am trying to think about speed of this cycle being connected to how many "frames per second" we can see. If the cycle is this slow then it means that to achieve the "refresh rate" of our eyes the cells would have to take turns, having roughly one cell in one (maybe two) thousand being ready to send new impulse at an arbitrary point in time (assuming normal light conditions. In a dark room all cells would be ready to fire. Except those firing spontaneously if this may happen?).
This reasoning seems to be solving a problem that probably does not exist in the first place ;) I mean the cells must be faster..
@@uid26 When I said the "full cycle" takes a bit longer, I was referring to not just phototransduction but the restoration of retinal to its original configuration (this is actually phototransduction and the retinoid cycle). Rhodopsin is plentiful in the cell (and not all of it is activated at one time), so I don't think the length of this process would limit vision under normal conditions (I believe the retinoid cycle might actually be longer than I initially estimated it at). The cell signaling would still be occurring on the scale of milliseconds. But honestly I'm trying to draw upon old knowledge without researching it, so I probably have this all off a bit. People have answered this question and published about it, but I'm unable to search for the answer now. If you find it, let me know!
@@uid26 So I talked to an expert on vision to get a more definite answer on this, and he confirmed what I was thinking, although I didn't have the times right (I actually underestimated them---the full cycle takes longer than I thought). The initial signaling changes associated with phototransduction are extremely rapid (on the order of milliseconds), but inactivation of the photopigment is a bit slower and the full recovery of it takes much longer (over 30 minutes in rods and a few minutes in cones). But the large number of photopigment molecules means that they aren't all used up at one time, so while some are recovering others are still free to be used. The individual I spoke to also pointed me to a paper that goes through the cycle in more detail: www.ncbi.nlm.nih.gov/pmc/articles/PMC3073571/
Thanks for such a deep answer. Now I understand why looking straight at the sun for a few second leaves a burn in effect and how we can see smooth movement.
👍🏼👌👏👏👏
💪🌹💯
Some day maybe we will know that a process by which electrical signals is converted to light, is happening in brain cells.
I read somewhere that it's the other way in insect's eyes. Cmiiw.
I believe in drosophila (i.e. fruit flies) the cell depolarizes in response to light. There are a lot of variations on this theme throughout nature.
I m in class 10tg tq
hi. i have a question so when the eye adapt to intense light, does the photochemical in both rods and cones will be reduced to rhodopsin? please inform me ASAP
These were the longest 2 mins in my life
did not understand anything
Professors now : i will report this channel 😀
sooo our eye balls eat light... nice.
grz fra ti devo un gelato
wut da hell
Too condensed, try 4 minutes.
Glory be to Allah 🙏🤲🏻❤️❤️❤️❤️❤️❤️❤️ Creator of everything