This video describes the definition of receptive fields and details the neurotransmitters behind the transduction of light. I discuss examples of off-center responses to light and dark fields.
Side note: OFF center bipolar cell receptors have sodium channels. If they were potassium channels, binding of glutamate would cause hyperpolarization and a lack of glutamate would cause depolarization. But it wouldn’t depolarize when there’s lack of glutamate because it’s an OFF center cell.
They are non NMDA receptors as opposed to metabotropic glutamat receptors on on center that is why binding of glutamat can result in two different outcomes
An exceptionally well explained video! I had my difficulties understanding it when it came up in my neuroscience course but now I can finally grasp the meaning! Thank you!!
Thank you so much! I have understood the lateral inhibition and the off and on center thing before hand but never managed to connect them! Thank you so much!
I didn’t know that the bipolar cells contained different receptors; but, now that I’ve learned it from you, everything is way more clear to me. This is the BEST. Thank you
Sarah the way you explained this slide was amazing, very easy to follow along and you made it much easier to understand. you should keep going with those videos, Especially since 70k views mean that most of us don't really understand this topic and might actually do well on our exams thanks to you! :)
Thanks so much, it helped me so much, even though it was in english. So much better than how our prof tried to explain it to us, I didn't understand a word back then :D
You can't possibly understand how the vision system works unless you consider the fact the this isn't about static images. The retina is designed to detect more than just light/dark and edges. It's all about detecting movement and that's all a matter of temporal processing which is left to the brain and I think that deserves a brief mention here.
Thank you so much Sarah, I have an exam in two weeks and my professor has tried over 10 times to explain this to me but I couldn’t get it. I even read the book that you picked up your slides from and didn’t understand but with you explanation I just GET IT!!!! Thank you so much 🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻
Thank you for the amazing explanation. I found one mistake about the glutamate receptor on the Off-center bipolar cell. (1:40-1:45) As others have already pointed out, this is not a K+ channel, but a channel for general cations such as Na+. So that when the channel opens, K+ does not flow out, but Na+ flows in, resulting in depolarization. Thank you.
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I have to know this crap for my Introduction to Psychology uni course. I’m only a freshman undergrad & I’m just so confused lol. This is very advanced biology material... I hope I’ll get the gist of it soon. Pray for me and my fellow confused psych peers 😭
Thanks a lot for your explanation! I also have a question, just to be completely sure: Can we say that we have ON-center-OFF-surround and OFF-center-ON-surround receptive fields in both bipolar cells AND retinal ganglion cells? :)
Hello! Great video, thank you. 1:43 Why does the cell depolarize when potassium is flowing out of the cell? (potassium is positively charged, so shouldn't it hyperpolarize?)
Potassium channels indeed lead to hyperpolarization of the cell. Glutamate activates AMPA receptors (Na+/K+ permeable) in the off bipolar cells, instead of potasium channels. These AMPA receptors lead to depolarization of the bipolar cell.
I have a question and i have searched all internet for this haha. But the space above and bellow spontaneous activity is Asymmetrical. So when switching light off the spontaneous activity van only drop so much before it reaches 0. This is a problem (i don't really understand why)? And that's one of the reasons why the cells have an on and off center, because of the asymmetry. But i don't really get how the on and off center help with this
It’s due to the amacrine cells that act to (partially) inhibit the central retinal ganglion cells. It’s not a strong enough stimulus from these amacrine cells to completely negate the output, however it reduces the firing rate of these neurones.
On center is having mGluR which is activated by low conc. Glutamate where as surrounding zone is having ionic GluR which is sensitive to high conc glutamate ....Less glutamate activates mGluR so more depol. at BPC as well as GC in on-center off-surroundings where as in opposite case when center is dark, more glutamate releases due to Hyperpol. and it acts on Ionic GluR so depolarisation occurs at BPC, GC....leading to Off center on surrounding situation..😊
Hi Sarah, first thanks a lot for making this great vid I have couple of question: 1. how are those rf connected to the different types of cells(simple complex and hypercomplex cells) is it that several of those rf connected to same cell in the visual cortex? 2. how are the different types of rf formed? as i understood we have 4 types yellow on-blue off, blue on-yellow off, red on-green off and green on-red off? if we only have red blue green cones? thanks again :)
Yellow is a combination of Red and Green! (counter-intuitive, I know!) Receptive fields are formed by neighboring fields of red surrounding green, red and green around yellow, etc. Several receptive fields do map on to single cells in the visual cortex!
This is above the scope of psych 100 right? I don't know if I'm going to fail my test or trying to learn something too advanced for my class. Is this necessary for the perception and sensation chapter of first year psychology
Nah. You don’t need it for 100’s psych, I would guess. All I knew for that class about photoreceptors was cones=color perception, rods=brightness perception. Hope you didn’t fail though
The default state of photoreceptors is depolarized in the dark (aka dark current). When light hits the photoreceptors it shifts the conformation of rhodopsin, leading to activation of a G protein pathway that degrades cGMP. cGMP is what keeps sodium ion channels open in the photoreceptors, so when you have less cGMP, the channels close and the cell hyperpolarizes.
depends, as an opthamologist myself i can tell you there are different types of horizontal cells that secrete different nt, but the effect is inhibition, there are 30 or so amacrine cell types and at least 3 ganglion cell types in humans
Could you please make a video explaining what that "patch of retina" in the upper left corner "is"? Are ganglion cells really microscopic little circles surrounded by a bigger circle which in turn is surrounded by a patch or retina? I thought that these "circles" were mere abstract representations of the visual field (in a sort of topographic map), as I learned from this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-oBJSG15Nq2E.html
