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In this episode, Leslie explains more about the connections between rods and cones to bipolar cells, and between bipolar cells and ganglion cells. He also describes how these connections determine the receptive fields of each ganglion cell. Enjoy!
Transcript of Today’s Episode
Hello and welcome to another episode of Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 33, I’m going to be talking about the receptive field of a ganglion cell. Let’s get right into it.
In order to understand the concept of the receptive field of a ganglion cell, we need to revisit the structure of the eye. I want to point out that we have this layer of tissue here that we call the retina. In the retina, we have the rods and the cones, and we said that the rods are for black and white vision and just for detecting light, and the cones allow us to see detail, it allows us to see color.
There’s another area, a specific region of the retina that we call the fovea, and this is a very important region because we have a large amount of cones, so much so that we can have up to as many as 150,000 cones per square millimeter. As you can see, that’s a high density of cones. We said that when light comes in, what the lens does is the lens actually focuses that light onto the retina. Specifically, if you’re focusing on an object, it focuses the light onto the fovea, and that allows you to see a lot of detail.
Now, if I am looking directly at my object, and let’s say this is my object here, and you have these photons of light coming off of that object, and that’s being focused onto the fovea. I can see the details of that object. If there’s an object that’s kind of to the periphery, over to the side, so let’s say this is the object over here that I’m not focusing on, that object is also going to be reflecting photons of light, but the photons of light won’t be focused directly onto the fovea. For example, it might be that the photons of light are focused up here.
Now, we still have some pigment here, we still have some rods and cones, not as many as we have in the fovea, so we’re not going to see as much detail, but I can see the object that’s to the left of me right now. I can see that there’s a keyboard to my left, I can see there’s a door to my right. I can’t see all the details of that keyboard and that door, but I can see them.
So, if the light is being focused on the fovea, with such a high amount of cones, a high density of cones, I’ll be able to see more detail. We’re going to look a little bit at some of the processing that happens that makes that possible. Don’t take these arrows as set in stone, I’m just trying to give you a general idea of how this works, but I hope that makes sense.
With that concept, let’s go on now and talk about the receptor field of a ganglion cell. To illustrate that, I’ve simplified the drawing of a ganglion cell, so here we have a ganglion cell, and here we have a cone. So these are all cones, and this is the same for cones or for rods, but we’re going to focus on cones because that really gives us a lot of detailed vision. The cones are connected to bipolar cells, and those bipolar cells are connected to ganglion cells. Here you can see we have one cone that’s connected to the ganglion cell via a bipolar cell. I don’t show that here, but just assume that a bipolar cell is in between here. Here we have another cone that’s connected via a bipolar cell to one ganglion cell. Here we have the same thing.
Over here, we have something a little different. We have 3 cones that are connected to one ganglion cell. Now, from the ganglion cell, we said that the ganglion cells have axons and they send signals to the brain. So, I’m just going to draw an arrow going to the brain from each ganglion cell, and I’m going to draw an arrow going to the brain from this ganglion cell over here also. This is the situation that we have in the fovea. Because we have so many cones, and in some cases, we have one cone that’s connected to a ganglion cell, when the brain is receiving information from these 3 ganglion cells, it’s getting a lot more detail. When it’s getting information from this one ganglion cell that’s kind of trying to summarize all of the information that it’s getting from multiple cones, it’s not going to be as detailed as the situation that we have over here.
So here, the receptive field of this ganglion cell is one individual cone, which gives it a lot of detail. So I’m going to say here, I’m going to say lots of detail. And here, it’s not as much detail. So I can still see what is being picked up by these cones, but I’m not going to see as much detail. So the receptive field of this ganglion cell includes these 3 cones. The receptive field of this ganglion cell just includes one cone. And this can go for cones, it can go for rods, and I draw this simply with 3 cones, but you can get thousands of cones that are connected to one ganglion cell. Of course, that’s not going to give you as much detail, but you’re still going to get some information that can go to the brain and be interpreted so you can see what the objects are with some detail, but not as much.
That’s all I want to talk about in this video. I hope this gives you a good idea of what we mean when we say the receptive field of a ganglion cell, whether you have very detailed receptive field, or not so detailed. This receptive field is larger because it’s connected to more cones, but you get less detail. The receptive field here is smaller, but because you have so many individual ganglion cells that are connected to individual cones and individual rods, that’s going to give you more detail.
If you have any questions about that, you can go ahead and leave them in the comments section below, and I’ll be happy to answer your question. That’s it for this video, and I’ll see you in the next one.
About The Author Leslie Samuel
Leslie Samuel is the creator of Interactive Biology. He created this site to help Make Biology Fun and has the goal of making this the biggest and best biology resource on the net.
1. March 2011 at 10:08 am
Hi i loved watching your video my concepts are really cleared thanks a tonne.:)
I would also want to more a little more on how color vision takes place.
Thanks
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Leslie Reply:
March 1st, 2011 at 10:26 am
Glad I can help clarify some of the concepts of vision for you Naqqiya.
In terms of color vision – There are 3 types of cones and these 3 types of cones respond to different wavelengths of light. 1 responds to Blue, the others red and green. When light comes into the eye, these cones are stimulated differently depending on the colors of light (wavelengths) they encounter. The brain then takes the information from all the cones, and the rods and combines them to make a full picture.
In terms of what happens inside the cones, it’s very similar to what happens in the rods, but with slight variances. For example, the pigments in the cones are different from the one in rods. In Episode 31, I talk about how Rods and Cones respond to light. That will help clarify the process for you.
Hope that helps!
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naqqiya Reply:
March 6th, 2011 at 12:38 am
Thanks that did clarify my doubts
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21. March 2011 at 6:04 pm
great video… thanks!!!
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21. March 2011 at 8:38 pm
@2420MeLinda You are very much welcome!
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24. April 2011 at 3:01 pm
so much better than my prof haha.. thank you
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25. April 2011 at 6:46 pm
LOL, hey, as long as you’re learning, I’m happy
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25. April 2011 at 6:46 pm
@kakaonkaka LOL, hey, as long as you’re learning, I’m happy
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4. May 2011 at 7:58 pm
its really cool how the videos are clear and to the point, but then you also put in your personality, which is awesome because you’re showing people that scientists aren’t boring old people
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4. May 2011 at 7:58 pm
its really cool how the videos are clear and to the point, but then you also put in your personality, which is awesome because you’re showing people that scientists aren’t boring old people
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4. May 2011 at 8:17 pm
Aww thanks. Glad to know that I’m exciting and young
LOL
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4. May 2011 at 8:17 pm
@beinwhitebites Aww thanks. Glad to know that I’m exciting and young
LOL
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11. May 2011 at 5:08 pm
hahaha these videos allow me to skip pretty much all my life science lectures XP
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11. May 2011 at 5:57 pm
LOL, Not sure whether that’s good or not
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12. May 2011 at 1:04 pm
this has helped back up my lectures and revision so well!. got my exams in 2 weeks so feeling a lot more reassured . any chance you will/can make a video regarding the magnocelluar system and the parvocelluar system. many thanks either way !. great videos.
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12. May 2011 at 1:07 pm
Glad you are finding value in the videos. Unfortunately, I’ve never even heard of those systems, lol. I’m actually following a sequence right now. After the Circulatory system, I’m moving on to the Respiratory system.
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12. May 2011 at 1:07 pm
@jaffacaker Glad you are finding value in the videos. Unfortunately, I’ve never even heard of those systems, lol. I’m actually following a sequence right now. After the Circulatory system, I’m moving on to the Respiratory system.
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8. June 2011 at 9:28 am
A correction – you state in the video that acuity at the fovea is sharper due to the high density of cones. This is incorrect – rods and cones actually do not vary in acuity. The reason vision is sharper at the fovea is due to the size of the receptive field of the ganglion cells in this region – not because of the fact that there are more cones here instead of rods.
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Lrsamuel Reply:
June 8th, 2011 at 10:11 am
Thanks for you comment. You are correct. The receptive field of the ganglion cells in the fovea does determine the sharpness of vision. In the fovea you can have a receptive field as narrow as one cone, from what I understand. But isn’t that also helped by the amount of cones in that area? I would assume so, but I also stand to be corrected. Let me know what you think.
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23. July 2011 at 8:48 am
this video it´s so right , the only thing i´ve got to be noticed is tha , befor the information arrives to ganglion cell has to get trhoug bipolar cell. Here in this video the bipolar cells are not present
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23. July 2011 at 8:48 am
this video it´s so right , the only thing i´ve got to be noticed is tha , befor the information arrives to ganglion cell has to get trhoug bipolar cell. Here in this video the bipolar cells are not present
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23. July 2011 at 8:48 am
@InteractiveBiology this video it´s so right , the only thing i´ve got to be noticed is tha , befor the information arrives to ganglion cell has to get trhoug bipolar cell. Here in this video the bipolar cells are not present
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24. July 2011 at 8:24 pm
You are correct. I did leave out the bipolar cells in this one intentionally. If you look at episode 35, I go into more details, including the Bipolar cells.
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24. July 2011 at 8:24 pm
@yAyIStoNe You are correct. I did leave out the bipolar cells in this one intentionally. If you look at episode 35, I go into more details, including the Bipolar cells.
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25. July 2011 at 9:58 pm
@Mansuya That has to do with more than just vision. People who read really fast have trained their brains to do so. There are strategies that you can apply and practice to become better at that. It involves starting farther in to the left, relying on peripheral vision, and not moving your eyes all the way to the right of the page. That’s a huge simplification. I don’t go into that topic on any of my videos, but there are speed reading courses you could take. All the best!
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9. August 2011 at 12:05 pm
thank you for the video. I was looking for a explanation specific pathway called Lateral Inhibition that I really want to visualize the process because I’m a visual learner
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9. August 2011 at 12:05 pm
thank you for the video. I was looking for a explanation specific pathway called Lateral Inhibition that I really want to visualize the process because I’m a visual learner
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11. August 2011 at 6:32 pm
You’re very much welcome. Glad to know the videos are helping you. Stay tuned for more!
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11. August 2011 at 6:32 pm
@peteryun1 You’re very much welcome. Glad to know the videos are helping you. Stay tuned for more!
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20. August 2011 at 4:30 am
Do the eyes see the world like a painting its 2d but with different colors its 3d.
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20. August 2011 at 8:54 pm
I’m not sure I understand what you are asking. Can you rephrase your question?
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20. August 2011 at 8:54 pm
@timandchrisfite01 I’m not sure I understand what you are asking. Can you rephrase your question?
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26. August 2011 at 2:37 pm
@InteractiveBiology I think that @timandchrisfite01 means that you said that we see the world like a painting, which is twodimensional. That is not incorrect, that is how what we see is reflected on our retina. Our ‘chiasma opticum’ (part of the vision center in our brain) translates our “2D vision” (transported by impulses through axons) into 3D. The brains are responsible for that, not the eyes.
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26. August 2011 at 2:39 pm
This has been really helpful for me! In may I’ll be doing my exams in biology and ‘nature, life and technology’ (a mix of physics and biology) and this cleared a lot of things up. Thank you for that.
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27. August 2011 at 10:34 pm
@Gedverderrie You are very much welcome. All the best on your exam. Let me know how it goes.
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27. August 2011 at 10:34 pm
@Gedverderrie Thanks for chiming in on that one. I hope that’s what he was looking for!
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23. September 2011 at 2:03 am
This is great. Thanks for posting this.
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30. September 2011 at 5:16 pm
great video. One question: You said the signal goes from Cones -> bipolar -> ganglion cells. I thought it was Cones -> ganglion cell -> bipolar cells -> photoreceptors -> pigment epithelium. tried looking it up and I’m getting both pathways.
plz clarify.
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2. October 2011 at 12:54 am
@crunkmonkiee All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.
All the best
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17. October 2011 at 9:12 pm
GOD BLESS YOU.
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18. October 2011 at 7:30 am
Same to you
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18. October 2011 at 7:30 am
@jilluminous Same to you
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22. December 2011 at 4:51 pm
cones, bipolar, then ganglion.
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22. December 2011 at 4:51 pm
@crunkmonkiee cones, bipolar, then ganglion.
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7. March 2012 at 5:01 am
thank you so much. God bless you!
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26. March 2012 at 3:45 am
THANKS!!
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30. April 2012 at 3:55 pm
bit too much simplified…
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12. May 2012 at 4:15 am
woah! watch out everybody. we got a badass over here.
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18. May 2012 at 9:08 pm
if you’re writing a PhD
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