Physiology of Excitable Cells BS2015_SEM1 KE LT1 PDF

[Auto-generated transcript. Edits may have been applied for clarity.] So I'll just give it a couple more minutes just in case we've got any, uh, any latecomers? Is everybody okay if I turn the lights down a bit for the lecture? Just because I've got some visual stuff in it that, um, works bett...

[Auto-generated transcript. Edits may have been applied for clarity.] So I'll just give it a couple more minutes just in case we've got any, uh, any latecomers? Is everybody okay if I turn the lights down a bit for the lecture? Just because I've got some visual stuff in it that, um, works better if you draw in here. Okay, then we'll make a stop. Right. So, um. You will have already had, Frank, I think, for two lectures this week. Um, we're thinking about a sensory integration and vision. So this is the third lecture, and I'm going to be thinking about enrichment. So why we move our eyes? Um, for anybody I recognise a few faces, but for anybody that doesn't know me. So I'm Rebecca, I, um, a research fellow for I'm also a clinical scientist. So I spend half my time down at the Leicester Boiling family. Um, and one of my areas of expertise is on movement, and in particular, a condition called Nostoc, which we're going to be talking about. Well, I'm going to be talking about this activity that Artemis. So we use sensory motor integration. Um. For eye movement works well for vision, for vision overall. So we use of sensory information in order to control movement. And we make movements to optimise sensory information. So in particular when we're thinking about vision we move our eyes. So the object of interest lands in the correct place on the retina at the back of the eye. So we're using sensory information to move the eyes because obviously you need to know what what what is the object of interest. And then we're making the movements to optimise that sensory information. So as part of this lecture today we're going to be having uh an overview of the retina. So the organisation of the sensory information how that sensory information is organised, is it going to the eye and then switch the brain. And then we're going to be thinking about eye movements and why we make eye movements. And there's six in general and the six categories of body movements I'm going to run through with you today. And then this afternoon at 3:00 to the lectures will go, not, uh, the resume. Um, so they do build upon one another. Uh, so this afternoon at 3:00, we're going to be thinking about pathological movements, uh, and also how we record these eye movements, which is going to be useful for your practical sessions next week. So in terms of the structure of the island, we can think about the AI, um, a little bit like a camera. So you with the with the AI like. So light comes out, um, to the eye is refracted at the cornea and the light. In order to hit the back of the eye and hit the retina at the back of the eye. So what we can think about, we can think of and compare it to a camera, because we can think that there's a lens system. There's an aperture which is the pupil. So lets the light in and out is a dark chamber, uh, which is actually a pigmented chamber in, in human. And then we've got the photodetectors or the film of the camera, the light, which is the retina at the back of the eye. And then we have the optic nerve, which is the, um, communication system to the brain. Um, so I always refer to the communication to the brain. So that's generally how the I work, the light coming in is refracted. It hits the back of the eye. It's like the film to a camera. And then that information is, um, in the form of electrical signals goes to the brain. So in terms of the retina, the retina is, uh, quite an intricate system, lots of interconnecting legs. So if we think about the retina from the outside in. So the retina is all, all the way on the inside of the, on the inside of the eye, on the outside, you can think of it on the outside coming in. First of all, we've got the splatter to the sclera is the white of the eye, and it's the protective after that. And it's comprised of collagen and elastin fibres. Um, really important is that is what keeps the structure of the eye, um, and interesting to humans, because it's most clearer than any other species that has a small iris. And this is really important for eye movements because not only around movement function. Also we can see the eye movements are also really important in terms of communication with one another. Then as we're moving in the next layer, we have the choroid. So the colonies are vascular. They're um, the oxygen and the nutrients to the active retina and in particular the phobia. So we're going to be talking a lot about the phobia because this topic is a really, really important structure when we're thinking about flying and flying. High acuity vision. Next level is the retinal pigment epithelium. And this is a pigmented layer to light absorption. You never said it was a dark chamber because we don't want too much light. Um bouncing around in in the in in the eye. So the opposite pigmented layer, the light absorption. And it also reduces oxidative stress. And it forms a really tight junction, um, that we call a blood brain barrier to the retina. And it's the RPE that supports iconic. In terms of the protective sectors, and we should be able to take this right back to a level. Um, but there's two types of photoreceptors. So we've got cones. And they are concentrated in this area. So again, we're going to be thinking about that structure shortly. Um, and codes really really important for high purity vision. Also for our daytime vision. So when we're in light conditions and our colour vision so intangible colour vision there are three different types of code. We've got blue code, red codes and green code. And then you have to talk proprietary statistics to rock the vote. What help you see in the doc. So our docs good topic vision. They're not present in the central vacuum. So there are no budget this year. Um, and overall there's about if you look at the numbers in, in a retina, we've got about 100,000,000W as compared to only £6 million. So then the next layer is the horizontal cells. Um, these are the neurones that connect the photoreceptors laterally. Okay. So you can see that they're angled differently. Um, we know that more information in lecture two because you will have already had those lectures I think. And again here as well. So I'm assuming that I spoke about this a little bit. And then we've got the bipolar cells. And they connect the photoreceptors to the retinal ganglion cells, and they actually facilitate the sensory processing through the horizontal and the amygdala cells. You see all these all these different. All these different, um, receptors. And so you can see how they're all linking together. Then we have the Omicron cells and they can actually connect the bipolar. And then you have the retinal ganglion cells. And these are the app cells from the retina. So these take the information from the eye to the bright. And then you've got four types. You've got a cellular magna cellular near cellular and photosensitive ganglion cells. And I can um I assume that. So it will be more information like we've changed the lectures around this year. So last year I gave my lectures first and then Frank gave his second. So I missed this here. So I think that Frank would have already spoken about this either in lecture one or lectures. That can give you some more information about that. Okay. So central and peripheral retina then. So if I was to look at them straight through to the back of your eye, we something that we call a slit is what we use in clinical. Um. Figure eight. That's what I would say. That's a funny image. So I was go straight to your people and look at the back of the eye. That's what I would say. And what we have here. So this is the optic that here. And these. I think it's quite vascularised. There's lots of little blood vessels in the eye. And this area here. This is the macula. This darkened area. And this is where? Right in the middle here. This is where the problems. Okay. This is where the popular is. So if I was to cut through this as we can. You have some equipment called an escape that can cut through, that can scan through cuts, very cut through the middle of the you and flip it on its side. I can look over the left. So you think about it. We're cutting through it. Open it up. Like if you were cutting through a cat, through a cake. And we're looking all the separate layers of the cake. This is what it would look like. This is actually a pit in the back of the eye. These top layers here are all pulling away. Okay. So you can see. So these are all the separate layers of the retina that we've spoken about. These are the two that have inside that correspond. Um and what you can see is you've got these legs pulling away. And the reason that they're pulling away is because when the light comes into the eye, this is where it needs to hit. This is where it needs to hit. This area here is full of code. Okay. And it's the code that we need for our shark information. If you're looking whatever you're focusing on. Sharp. You can see all around you, but it's not sharp. Okay. You aware of things are going on around you, but it's not your sharp vision. And that's because. Wherever you are, focus. That's where the light is. And you know that that's where the light. Um. That's where you're taking the light in in order to do that image, land on that fovea. Okay. But the back of the eye. So then when we think about the central and peripheral retina that we've just as we've just spoken about rods and cones. So we've only got cones even for real. Okay. And then the rods around about size is the object. Um. Probably never. There is the opcode in the peripheral retinal, but we only find cones at the 12 year. So what you can see here is so this is so this is before we are here at zero. And we've got this is supposed to be set to density at the site. So we can go on either side of this area. Um you can see that increase in in in involves. And the interesting thing is we talked about the, uh, the vegetable ganglion cells and then B the output cell for the retina. Um, if you think about rods and cones and again, this is another reason why vision is so clear when we use our cones. It is, um, which is if you consider convergence to the number of retinal, um, number of, uh, the photoreceptors that connect to a retinal ganglion cells do in terms of what you can have an average of about 120 rods that connect to one retinal ganglion cells. So there's lots of information going in from lots of rods into one retinal ganglion that. Um, outside of the phobia, there's an average of about six cones to one retinal ganglion cells the size of the altcoin, as you can see there. Here and here. Outside of this will be the atmosphere. The convergence is one code to one retinal ganglion cells. So you've got a direct connection there if you like. Okay. Even though you've got all those other interconnections along the way when you get to that retinal ganglion. So it's just one piece of information going through rather than lots of bits of information for many months to almost no. So this is a copy of that. So this is what happens at the top. Yeah. Um, so you've got these long narrow cone after segments. Here. And because they're long and narrow. Alaska. Um, high density parking lots and lots of cones all packed together at the top because they're long and. And then what you think the Heavenly Father is, which is the axons from the photoreceptors from the cone photoreceptors, light even obliquely. So here and here. And that allows the formation of this. So the inner layers so the most inner lives are deflected sideways. You know we talked about they pull away so that light can get through. It can get out of it okay. And then either side you've got the retinal ganglion cells. So I decided to call it an inverted pyramid if you like. We looked at the copy with the pic. And I looked at the map. Um, but it's the same principle. So when I talk about visual acuity, um, I'm talking about visual acuity. Um, what we can measure on an eye chart. So many of you, if not all of you, will have been to the opticians before and you should be familiar with, um, these kinds of eye charts. And this is how we measure of visual vision. That's what we're interested in. We're not interested in really what you can see over here when we're talking about visual acuity, we're interested in our fine spatial FOV. Your vision. And this is equivalent. So when you get down to way the maximum squat to the smallest that you can reach, that's equivalent to 1 to 2 diameters in normal vision okay. That's what we're looking at. You want to cone diameters. So why do we move so? We move our eyes. Because these coins are most densely packed in that area called the phobia. That actually is 0.25mm across. Its tiny. Okay. So we need to make these on movements, whether that big gross eye movements or fine small eye movements in order to make sure that the light is refracted onto that view at the back of the eye. So we move our eyes first of all to bring the image up. Okay, so we might make big movements to bring that image on to the full view at the back of the eye. But then not only do we want to bring it on there, we want to keep it that. There's no point is bringing that image onto the copier and then moving away. So we need to keep that image there. Once it set. Can we do that then? You see another movement. So we've got, um. I'm saying the six classes of movements. And the first one is the case, and we use a case in order to bring the image onto the carpet. And I'll be talking through each of these different types of eye movements in a moment. But initially we make a case if something comes into view that we're interested in, we'll make it a case in order to bring that image on to the podium. And then to keep the image on the subway. Once it gets that, we can use fixations. We can use. Wait to see. We can use optogenetic. Nice. Spackman. There's a particular ocular reflex. And then we also have the justice treatment. I'm just going to think about these different types of immigration one by one. In a moment. So if you are scanning a visual scene, you would tend to use the caveman situation. So you would use a fast movement to bring your image. Wow. To bring your eyes to the debris of the image that you're interested in. And then you would fade for a period of time to replace it with giving a talk. And then you might want to look at something else on that image so you could move again. And then that would be change. And then you would make a fixation. This is that really really quick movement. So what you can see here and yet you can see elsewhere. Um so if the eyes were to start here, they make this a case to point to. And if you look at point two, the duration is 111 minutes before it moves to point three and 188 milliseconds spent there. And over to number four we got there 251 million. So we got to see if a really speedy, speedy, um, really. Well. So it's a speedy succession of movements, if you like. Because if you think about it, you probably want to scan that before you see it and then you want to move on to the next thing. Everything that we talked about here was really quick. Can also use the and fixations when we're reading. So if you look at the green um. Circle that is moving around. So basically somebody has got an eye tracker on here. And what you can see that's the screen that they're looking at. And as the, the um the green the green circle is moving right here up over this, you can see there's a series of decays which is a jump. And then after each decade, there is a, um, fixation. What about moving images? Obviously, these are all stable, stable images. Uh. Is it? We're thinking about it. We're reading some text. It's not moving. Looking at a photograph. It's not moving. So what about moving images? So when we talk about moving images, the head can be moved and the whole body can be moved to think about the head to move in, but you're not seeing everything moving around you. So when they had, you know, your whole body is moving, you have to be talking to these like. When a single object of interest is moving. So if you wanted to track something from one place to another. We've got this, this film, which is a really, really clever system. And then when the whole visual field is moving. So for example, if you were sat on a train or in a car and everything's moving at the side of you. We've got octo connected in I stack my. Say so. Somebody is wearing an eye tracker again and the yellow circle is where they're looking. So the driving a car and as you're driving the car, you're looking at lots of different things, aren't you. So you're always scanning the scene. Now you can kind of fixation. It had to be moving around. You know, ocular reflexes. Maybe there's a car coming in front of him. So that's a single objective, um, interest. Uh, so he's tracking that. We just make them do. Generally, what you can see here is we're using all these different eye movements together all the time. We're not just making decays and fixations. We use it. We're utilising the. Or the wrong movements as well. I'm just going to think about those arguments now. So just thinking about the case first of all. Okay, so we've talked about tacos, but let me just talk about this, ma'am. First of all, this is you're going to see this map for each of the different types of immigrants. You're going to think what she chose in that for because it's not the most attractive picture, is it? So this man is, um, how, uh, how about Herman Van Helmet? And having been helmets, was that, um, back in the 1800s? He was the first man to. Was the first scientist to put plot out on what we call the nine positions. Okay. Um, so when I'm examining a patient, I'm interested in nine positions. Okay. So we've got central and either side central up on either side and at the bottom on either side. You might think, well that's great. Big deal. But he also able to use or invented Yorktown Moscow. So for anybody that um I've been to the optician and the optician got it. He's like a, it looks a bit like a lollipop. Really, really close to you to look at the back of the I sat down on Skype. So if you work, you know, if you're working I really important guy because without him, we wouldn't have been I haven't been able to look at the back of the eye. Okay. So we come in the back of the eye. So I'm just going to play that video again anyway. Now I'll finish, um, explain who he is. So what you can see. So. There's a finger on the fingers moving and there's a finger move. His eyes are moving and it's just moving from side to side. Okay, so what we would probably do clinically actually, probably would just have one thing you'd have to and you get those patients to go from one one to you. That's just a device. That big movement that requires movements is to move that image onto the clock and move the image onto the cover at the back of the. So as I said, the purpose of them is to move the image on to the copy at the back of the eye that really very rapidly movements. I mean, we saw that when we when I was showing you the image of the photograph and when we were scanning the photograph, um, um, earlier on the image of the face, um, really very rapid eye movement. So they've got a very short latency of about 200 milliseconds, and they move up to 900 degrees per second. So really, really speeding. And these are classed as a voluntary eye movement. So you'll hear me talk about voluntary and involuntary eye movements. So voluntary means we choose to do it involuntary. It just happens. Um so that's voluntary because they're in response to stimuli whether that's stimuli visual stimuli auditory. So something that we hear touch or memory. So we can we can have memory the case as well. And they are conjugates. So you hear me talk about conjugate eye movements and this conjugate eye movements. And that'll be really important for this afternoon. Um to conjugate eye movements. Both eyes are moving at the same time in the same direction. So as one I move here that I move at the same time in the same direction. Okay. So that's a conjugate eye movement. So that voluntary we choose to make them and their conjugate. So both eyes are moving at the same time and in the same direction. What does this look like? So you're probably looking at this and thinking, oh my God, what is that? So this is an eye movement recording. So this is what you're going to be doing in your practical session next week. So in your practicum session next week, you're going to be recording your own on movements using a system called um EOG, which I'll talk about this afternoon. So what we have here is a cost bottom. So this is the output. So if you think about actually so let's think about how we're going to record that. You've got a setup whereby somebody is looking at a screen and they're following a dog that moves from place to place on the screen okay. The stop is appearing, disappearing, reappearing somewhere else. So it's moving from place to place and the eyes are tracking that movement. So you got to. I got a left eye in a right I. See, you've got a left eye and a right eye and then you've got the target. Okay. So what the target is doing. So what we can see the targets do is it starts off at zero here. And then it moves. So when it goes into the mind, I think moving to the to the left and then stays in that position and then it moves back to the centre and then it stays in that position. And then it moves across again to the left, but not quite as small as before. Yeah. And then it stays. It's does actually time across the bottom. So you can see here it's not moving across this period of time. And then that makes sense. So then what is left I doing and what you are doing. So you can see here. So this is a fixation. It's not moving staying at zero. Then we've got okay okay. It's fast rapid movement. So just bring the image onto that. Um just bring the eyes onto the image and then it stays in that position and then it moves again because it means that the eyes everything can see here. Right? I left eye doing exactly the same thing at the same time. So what you can see is that these believe it or not, these are really very good. Okay. These are, um, what we think of as being normal. So this is what your if you had normal eye movements, this is what you would look like. But they're not completely smooth. You know they're not exactly doing what the, what the TOG is doing because sometimes we overshoot or undershoot okay. So sometimes we don't quite get to the target. So we need to make another little okay to get there. Some people can overshoot the target. So then they need to enter the decay to move backwards. And that's what these are here you can see here I for example I didn't move but it's gone a little bit too far. This is like um what we call a corrective. Say okay to bring that image into the right place. Okay. So you've got your main stage and then you've got the fixation and then he again, you can see this is corrective to say, but it's not quite got to the target. There's a tiny difference okay. Let's make that. Okay. And as I say, both. Are you doing the same thing at the same time? That we have a fixation on movement. So you probably thinking fixation still if you fixation really an eye movement but it's. Uh, he did a demonstration here. So what I'm going to get you to do is obviously this. Which means you just pick one of them and just set the black spot for me in the middle. And I'll tell you what I want you to do. Just keep looking at the black spot. Just for 10s or so. And now I want you to move your eyes and look at the white spots in the middle of the square. And what you should say. You should see an after effects of the great. Within the black square. But it's not said it's moving. And we will see that. It's not so. And what that is, is that is so that it says is the after effects from the second the image, the white image on the retina. What you can see is it's moving because the writer never completed. So we're making what we call fixation line movements all the time, very small tiny eye movement in order to keep that image on the full view of the back of the line, and that there is a demonstration of that fact that that that great still is moving. Once you see the actual effect, it's not a that's regression line. So again, so the fixation line movement. The purpose of them is to keep the view on the fixed target of interest. And they could probably comprises a miniature army. So as I say, the term fixation suggests that it's still but it's not quite still. Um, it comprises is comprised of miniature eye movements which are called micro six and seven. So the easiest way to describe them is to look at them. So if we think of this as lots of photoreceptors all packed together. So we talked about cones. Didn't we have a kind of all packed together that long and thin, densely packed at the phobia? Okay. And then you've got the eye movement. Okay. The eyes are moving to keep that image on those kinds of the back of the eye. So I'm a Micro-SIM card. I'm actually very, very, very tiny six which bring me an image back towards you. So if the image moves away from the centre of the phobia. So, um, my first case is very, very tiny case which bring the image back towards you. And then we have drift, which are slower than microseconds and a bit more random and a bit more wiggly. And then you've got tremor. And actually tremor is a super imposed on top of a drift. So these are tiny, tiny, tiny movements. Um, what we would call subclinical. You wouldn't see them if you would just look at somebody. Life. We can see them actually record eye movements. But what we would do, we would turn these subclinical movements. So tremor A is fine oscillations. It's superimposed on top of a train. So that is three different types of fixation line movement. And you're probably thinking why you not even are so tiny. Why? So this time, I want you to choose. I want you to, um, I don't know. I mean, you can quite seriously. Can you see that there's a on that, like, right in a circle. Can we see that? Right. So first I want you just to stare at the red dot. 777. And what you should say is that great stuff comes in and out. Sometimes it starts to disappear and then it will reappear again, particularly if you if you move your eyes, you'll be able to see. So you, um. You know, you voluntarily realise. And that's what happened in those retinal adaptation. Okay. So if we're staring at an object and there's no eye movement for any period of time, the retina starts to adapt. It loses sensitivity to the area that you're looking at. So these find small, tiny fixation line movements also prevent maximum retinal adaptation. Yeah. So hopefully you can see that on the on screen. Probably easier on the smaller things, actually. Very important. Probably more important in days gone by, you know, when we were hunting and, you know, being hunted, um, to prevent infection and adaptation, we need to be aware of everything that's going on around us. Okay, so, uh, our third on refund line is my PC. Okay, so we saw Hazel Herman again. And so you can see the finger. And the finger is moving. It's a smooth movement from side to side. And his eyes are tracking that movement. Okay. Slow. Movement from side to side doesn't necessarily have to be a slow movement. It can be a fast movement from side to side as well. And we'll talk about that. So makes the see. I'm even saying the purpose is to track a single moving target. One moving target, not multiple moving target. It's just one moving target. But with this matrices system, as I said to you previously, it's quite clever because it requires the brain to estimate how fast the target is moving. Okay, so the brain makes a judgement on how fast that target is moving. And sometimes it can't keep up. And again, we'll talk about that in a minute. But it has pictures, but even it can't keep up. It has a mechanism for catching up. So again this is a voluntary movement okay. We choose to make it. But you cannot make this type of movement if you do not have enough data to track. Okay. And you look at this in your practical session and you see. Have this. Well, what sort of movement you would get if you don't have a moving target, you can't really estimate the eye movement with that moving target. And again this is a conjugate eye movement. So conjugate base eyes doing the same thing okay. Moving in the same direction at the same time. To watch this movie. You see, I mean, look like. So we've got that eye tracker again. We've got that target moving to this time. No, the target is moving smoothly from one side to the other side. Okay. This is the target. Yeah. Over time, it's moving from left to right. Right to left. Left to right. Right to left. Yeah. And then we've got our left eye and we've got our right eye. You can see the left on the right eye tracking the eye movement. And I'm slightly moved from left to right, right to left. But it's not a completely smooth movement, is it? You can see again, it's not perfect systems. Not perfect. So what you can see at times. At times there little time to catch up. Okay. So it's smooth. So that's used. Wait to see. And then it's not quite keeping up with the target. So there's a little tiny catch of the page and then a tiny catch okay. So basically what happens with this system is it can only track up to a certain point. It's not perfect can. And in terms of speed as well. It can only track in terms up to a certain speed. And again you look at this in your practical section and you look at these catch application you practical session as well. So it'll move to certain points for certain speed. But it's not quite keeping up with that target. The brain says I'm not quite on that target. We need to do something about that. And so very clever really makes a different catch. Okay. So again, you can see that the, the different types of eye movements really that we're working together all the time. So often the type of movement is opto kinetic knockback. Okay, so what we've referred to is okay and for sure. So what you can see here. So the stripes in the moving and the moving visual. See the visual scene is moving okay. It's going from left to right. And what you can see is Hammond's eyes are tracking it to a certain point, and then they're coming back again, tracking it, coming back again, tracking it, coming back again. So the purpose of okay is to track movements in the visual field. So when your whole visual field is moving and the times that you may have noticed this on somebody else, I don't know that you would like to be on yourself, but you may have noticed if somebody else is, if they're you on a train or in a call and the visual scene is moving inside of you and, um, you see the eyes making it very fast, okay. Or, um, sometimes, you know, it can be a little bit more discreet than that. You know, it doesn't have to be a huge moving visual field, but you would just see the eyes making these little movements for a period of time. But when the visual field seen the visual field stops moving so the eyes, it becomes gaping again. So this has a slow phase. So that's slowed slow in the direction of the target or the direction that the visual field is moving. And then a fast pace to be exact by okay slow pace. That's right. An involuntary movement. We don't choose to make it. It just happens. But you need a move in which you feel for it to. For it to work. It's driven by a moving visual field. But again it's a conjugate eye movement. So both eyes are moving in the same direction at the same time. What does it look like? Okay, so I've not got. So you see this trace looks a little bit different because we've not got a target trace on that. It's very difficult to to create that target trace. But you can see we've got the left eye in the right eye. So it looks very much like a sawtooth. You can see it's very jagged. So you've got this slide very fast. So here you've got a linear. Linear slope is here and that is where the image is. Um. That's why the eyes are tracking the moving visual scene. And you've got this pathway. And then you've got this fact voted is correct in the eyes and bring it back to the centre. It's like very fast, right? I mean, it doesn't look particularly slight. But that's the way that we would categorise that kind of type. And you can see that it's quite rapid in that, you know, we've got what we got there. You've got less than 10s there. And there's lots of movement within those 10s. So really super fast movement. Okay. And the idea is that we stabilise in that image on the full view at the back of the. So number five then is obviously below ocular reflex or that they are all. Okay. So we've not got. We've not got a target here. But what you can see. So the idea is, is that you've had to moving and you had to move in to lots of different directions. Can't get you know, that you can move to the side. You can move around as you're moving your head. You're not you're not seeing the world is moving on you. You know, there's a stable image. So it compensates for head movements. And it keeps your gaze steady and it is extremely rapid. Okay. It's actually the fastest reflex in the human body. And again, this is an involuntary. I'm even. We don't choose to do it. It just happens. But it is driven by the disability system. And this is a conjugal eye movement. So again both eyes use the same thing at the same time. If we didn't have a mosquito locally. Ocular reflex. This is what your world would look like. Okay as you're moving around. Everything would be moving. As your head moves, everything would move around. Okay. This is called ocelot. The perception of the world moving around. And again will be mentioned in this world of up to you. You'll hear that again this afternoon when we talk about pathological engagement. So when I say pathological, I'm used to abnormal I mean. So the system, then I'm thinking that Frank might have touched on this, but I'm not sure. So I'll just run through it. So obviously Billy's is still located. It's probably a. And you have three semicircular canals. Yeah. And each of these semi semicircular canals have slightly different angles. And within the semicircular canals what you've got is you've got a fluid that runs through these semicircular canals. And because they're all at different angles, the fluid will run through and. Depending on the semicircular canal, depending on which position you thought you had. Okay. The semicircular canals. Um, there's also so. So the stimulation, because there's little, um, hairstyles in there. So you move your head into one particular direction, one of the semicircular canals will be stimulated. And that lets you, your brain, know what position your head is in. The circular canals also horizontal movements, vertical movements and then the rotational movements of the head. In addition to that, you've got the otoliths, um, organs, which is a beautiful and it's accurate and they accommodate for and let the brain know when you're making translation light and movement so side to side, you know, when you have somebody go from side to side, opened up so that when you're in a lift, you're in a lift and you're moving opens up. Okay. You get that funny sensation, um, and it's the, uh, neutral in the kitchen to let the brain know. Which where the head is moving. And these organs all, um, they all interact with the vestibular nerve and you hear. So in short, the distributor answers the civil system answers to questions. Where am I going and which way is up? So if I had rotation, as I've just said, you've got those semicircular canals with side to side up and down. And when you're tilting. Okay. So three semicircular canals, line three orthogonal um planes. And then for head translation so side to side this way and up and down. And you've got the utico which is the horizontal movement on the statue which is sensitive to vertical acceleration. And as I said, they're both known as the obsolete organ. So yeah. So here we go. So the rotational movements, the centre of it is the semicircular canal. And for translational um movements is the opposite. This is something that she did clinically. Um, so you can have lots of issues with the disability system. And this is a barony chair and this is something that they use. So they have this down in the list of all in fact, when they certainly did used to have it. And they, it's in the um, ANC department. Um, you know I. So they, um, can use this chat to stimulate. We can talk to disabilities. Um, and look at the disability system and see what it is. That's that's gone long. If you like. It is also used by the Air Force. I understand, um, pilots. Uh, I put in chairs like this in order to kind of simulate what it's like, um, to be up in the air and having the visibility to be affected by, um, speeding movements. Uh, if you're a pilot, as in, in the actual pilot. So the auto connect technology, documentary, film and video all actually work together because they respond. Differently to different scenarios, um, but can work quite well together because of the way that they respond differently. So in terms of the ball, this is a rapid, immediate response. You know, we said it's the quickest, fastest reflexes in the human body and it responds best to brief stimulation. So we get to kind of moving around with it and essentially driving sensibility to. The icon system response is a slow build up. So as I said to you, you know, next time if you want to try and arrange a call, watch somebody die movement. And you, you see that it's a slow build up to that movement. You know, it starts off small and it gets bigger. And respond best to a sustained stimulation. Okay. So sustained, um, movement of the visual feed and the sensory drive. Individual. So our last type of volume is burgeoned. And this is a simultaneous movement of both sides to maintain single binocular vision. So when we talk about binocular vision. That is. And again, I'm pretty sure that Frank will have spoken about this in his two lectures. So binocular vision, then, is how we use both eyes together in order to in order for us to have depth perception, if you like. So we're virgins. Um. So you've got two eyes and the images from those eyes. Each one is slightly different. But the image from each of those eyes must be in the centre of the retina. And this allows for viewing at different, different different distances. But when we view an image, it nay our eyes made in inwards. Convergence. It is never that something is to you. Your eyes will converge. And if you appear in a distance. The eyes diverge. Okay. The farther away you're viewing, the more divergence you've got. So this is not a conjugal eye movement then, is it? Because both eyes are going in different directions. Um, but it is a voluntary movement, um, and it's driven visually. So virgin saw him leave it. So as I said to you, each image is slightly different. So if you put your stomach in front of you and cover an eye and then move to view the eye, but look in the distance and what you see. You can all do this. The front cover, and I and I moved to the other side. And you're looking in the distance passed out. So what you'll see is that each image is slightly different. That's retinol disparity. And is the way the left and the right eye view slightly different images. So it's this we need these versions. I'm using this because, um. It's really important that this retinol disparity. Uh. Is utilised properly because we need those two images to blend into one image. And this is really important for depth perception. It allows us to see how far away things off limits. And the way it works is that the, um, depending on the distance that you're viewing, that will depend on how much better results you've got. And the closer the image is to you, the greater the disparity between each image. And as I say, that helps us in terms of, um. Deciding how far away things are. Off limits. So depth perception. Okay. So that's it for this lecture. So what I wanted you to, to try and hold off for this lecture is understanding the organisation of the retina and the uneven distribution of both sets of photoreceptors to provide a region of high purity and vision. And so that heavy been for Sophia. I want you to understand how we use eye movements to stabilise retinal images and optimise your input. And also understand the complementary features. Okay. And available. Okay. So I've got you again at 3:00 this afternoon. Okay. So this we'll be talking about pathological line movement. So it will kind of it will fit together quite nicely. All right. So I will see you all at 3:00. Okay, so what are we talking about? Can you. Say that? Okay, so let me have a look and see what we've got. Okay. Hold on and tell me. Oh, my God. I just want to clarify. Okay, so let me see you. Let me have a look at it right now. Yeah. So I'm hoping that I hope. Have I got all my time? On what might. Happen on the opposite side if you will come time. Um, I say I. I feel. And I. I don't want to talk about. I. Um. Uh, yeah, I think we got our. Because I didn't want to. Uh, yeah. Maybe not. It never does happen. All right. See you this afternoon.