| 00:02 | All right, y'all. So this the last slide we were looking at |
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| 00:06 | when we left and what we're gonna is we're gonna finish up with the |
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| 00:08 | today. Um We're gonna look at transduction. That's really the, the |
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| 00:13 | of the crux of what today is with regard to vision. Then we're |
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| 00:17 | jump over the ear. We're gonna with hearing, we're gonna deal with |
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| 00:21 | or balance whichever way you want to it. And then we're gonna start |
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| 00:24 | through uh the motor pathways and I know how far the motor pathways we're |
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| 00:29 | get my slides, push us like through, but I don't know what |
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| 00:33 | gave you guys. And so we'll um it's gonna feel like there's a |
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| 00:38 | of slides today, but many of are just gonna go click, |
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| 00:40 | click, click, click because it's of an animation. All right. |
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| 00:43 | , um I don't want to go this. I just want to remind |
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| 00:45 | we were talking about rods and cones the differences between them and what they're |
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| 00:49 | used for. Do you remember these the photoreceptor cells and what we were |
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| 00:53 | is that one of, one of first things we were saying was, |
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| 00:56 | , um the rods and the cones like differentially located within the retina. |
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| 01:02 | . One is responsible for uh seeing light. One is kind of responsible |
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| 01:06 | seeing in the dark and this particular right here is trying to demonstrate where |
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| 01:11 | gonna find rods and cones. And what you're doing, uh anyone here |
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| 01:15 | on going to optometry school? thinking about it. OK. Um |
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| 01:19 | ever been to an optometrist to see pair of glasses, pair of |
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| 01:23 | you know, contacts, you you know, when they come at |
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| 01:26 | with that big giant bright light and shine it into your dark pit of |
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| 01:29 | soul of an eye, right? we said that's all black in |
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| 01:32 | This is what that picture looks That's what they see when they're going |
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| 01:35 | there and looking. OK. So looking into the the space of the |
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| 01:41 | , all right. And so this what they see and you can see |
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| 01:44 | . This is directly behind the So that's called the macula in the |
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| 01:49 | of the macular luia, this little indent that you kind of look at |
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| 01:52 | the images that's called the phobia You'll see blood vessels and this point |
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| 02:00 | the blood vessels are entering, which visible is also the same point where |
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| 02:05 | optic nerve is located, right? call this point, the optic disc |
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| 02:10 | the optic disc is your blind Now, were you kids, did |
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| 02:14 | ever do the, uh, optic the blind spot test where they put |
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| 02:18 | a two dots about three or four apart? And you actually look at |
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| 02:21 | dot And you just kind of bring piece of paper in and then the |
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| 02:24 | dot disappears. Have you done No, it was something they showed |
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| 02:28 | like in third or fourth grade. see. Um And basically what it's |
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| 02:32 | you is where this blind spot is you have no photoreceptors there. And |
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| 02:36 | just the point at which all those from all those ganglion cells are actually |
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| 02:40 | up together and exiting as the optic , right? But what I wanted |
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| 02:45 | point out here, so first, should know what these things are. |
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| 02:47 | macula is directly behind the phobia That's where all the uh cones |
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| 02:53 | all of them, but most of . And if you're to map it |
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| 02:56 | , this is what this is, a map. It's saying look |
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| 02:58 | we've done this, we flattened it . And if we count up all |
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| 03:01 | number of cones, the green line the cones. You can see as |
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| 03:05 | out here in the periphery, there's a lot of cones, but all |
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| 03:08 | a sudden you get to that phobia is basically nothing but cones. You |
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| 03:12 | use a picture to kind of guide way. And then if you look |
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| 03:15 | the rods where the rods is, , well out here the rods are |
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| 03:19 | frequent. And then when you get the Phobia and, and specifically at |
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| 03:24 | , uh, yeah, the Phobia , uh, there's, there's |
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| 03:27 | it's all cones, right? And it's just kind of a way to |
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| 03:32 | of visualize where these things are and of gives you an impression of what |
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| 03:37 | responsible for. So that clear vision see moving forward, what we've talked |
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| 03:42 | is because of the cones, the vision you see out here on the |
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| 03:46 | , that's partly cones, but it's the rods that take place or that |
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| 03:51 | involved in that. Now, one the things we're gonna see this, |
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| 03:55 | , this term adaptation twice when we about the eye is the first time |
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| 04:00 | we're dealing with the question of the rods and cones we said are |
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| 04:06 | for one light vision and one is vision. That doesn't mean you can |
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| 04:11 | in the dark there has to be sort of photon available, right? |
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| 04:15 | like if you wake up in the of the night to go to the |
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| 04:18 | , I know you guys don't have do that like old people do. |
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| 04:21 | you know, on that rare you know where you drink like |
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| 04:24 | a big gulp right before you went bed, you have to get up |
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| 04:26 | like four in the morning to go , you, you get up and |
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| 04:29 | you look around, you can see there's a little bit of light shining |
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| 04:33 | the shades or through the, through window and you can see around the |
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| 04:37 | well enough to understand what's there. . So, for example, you |
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| 04:42 | see your dresser, you might see big pile of laundry in the |
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| 04:46 | It might be a pile of It might be a monster. You're |
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| 04:48 | quite sure, but you, you at least see it, right? |
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| 04:53 | that type of vision is what the are responsible for. All right, |
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| 05:01 | , when they're hit with light, basically respond very, very quickly. |
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| 05:07 | what we do is there's, we're see this process. It's a, |
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| 05:10 | a recycling process. And what happens , is that once they're excited, |
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| 05:16 | takes them a long time to adapt back now to visualize that or to |
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| 05:23 | that. Have you ever been to matinee? You know, like a |
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| 05:26 | matinee? Right. And you go you watch the movie, it's nice |
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| 05:29 | dark and then you go outside and Texas sun hits you, you |
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| 05:33 | it's like three o'clock in the afternoon you can't see a thing. |
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| 05:37 | It's because your, your pupils were dilated, right? And it's used |
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| 05:41 | being in the dark and then you outside and all of a sudden it's |
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| 05:44 | every light photon on the planet is hitting your eyes. And so what |
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| 05:49 | do is we call that bleaching where literally, we've activated all the rods |
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| 05:55 | the cones are kind of overwhelmed and like, ah, and then people |
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| 05:59 | , you know, you know, really, really tight. But it |
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| 06:02 | take that long for you to be to start seeing outside, does |
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| 06:05 | But if you do the opposite, you go from a very, very |
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| 06:09 | area into a dark area, it a long time for you to get |
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| 06:13 | to that dark because remember the rods the ones that are responsible for that |
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| 06:18 | . They didn't take a lot of but because they've been bleached the entire |
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| 06:21 | while you've been outside, they are about 20 to 30 minutes to adapt |
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| 06:26 | to those low levels of light. gonna show you how that happens. |
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| 06:32 | , what we refer to this as this is just an example here is |
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| 06:35 | , I mean, these are this is not really what you're, |
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| 06:38 | this is like what dark vision is , right? I mean, you |
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| 06:40 | see the objects but then it's not clear the details. But in when |
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| 06:45 | , you know, if this was , this is, you can see |
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| 06:47 | different colors really well, you can the brightness and so on and so |
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| 06:51 | . So this would be an example how your cones see the world. |
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| 06:55 | is how your rods see the All right. But rods don't respond |
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| 07:00 | code, they don't allow you to color. What we call this, |
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| 07:05 | kind of view using cones is photoop . All right. When we're talking |
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| 07:10 | what the rods are, are, , yeah, what the rods are |
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| 07:13 | . That's scoop. So night what you, what you would call |
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| 07:18 | night vision would be scotopic viewing and can really kind of experience this uh |
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| 07:23 | really early in the morning. When before the sun comes up, |
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| 07:26 | you know, it's kind of you can see the details, you're |
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| 07:29 | scoop. But as the sun comes , you switch over to faux topic |
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| 07:32 | when at sunset, which is like 30 right now, it's the |
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| 07:36 | It's like you're used to being able see stuff you're going from scoop, |
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| 07:39 | there's that period of time where it's hard to see stuff and then all |
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| 07:42 | a sudden it's not so hard. that's you're switching from faux topic to |
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| 07:46 | vision. There's a lot of information this slide I don't want to deal |
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| 07:52 | at all. I just want you understand what bipolar cells are. All |
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| 07:56 | . So here's your uh photoreceptor bipolar cells are the, are the |
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| 08:02 | that are downstream, they respond to . So when the, when the |
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| 08:08 | receptor cell produces its greater potential, releases a chemical message that can turn |
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| 08:13 | or turn off cells downstream. Those be the bipolar cells. All |
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| 08:17 | That's what, what I want you understand right now. I don't, |
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| 08:22 | almost 100% certain. I don't ask about on pathways and off pathway stuff |
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| 08:27 | I just confuse students when I talk that. So we're gonna leave it |
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| 08:30 | that. OK. Oh. And cells synapse with the gangle cells. |
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| 08:38 | so photoreceptor bipolar gang cell, it helps us understand this a little |
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| 08:46 | Maybe that's why I throw it OK. So what we're looking at |
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| 08:50 | , we talked about receptive fields. we talked about what touch the receptive |
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| 08:53 | . And I said that's not the thing that has receptive fields. |
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| 08:57 | you have receptive fields in, in gustatory system, you have receptive fields |
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| 09:01 | the nasal, you know, in nasal epithelium or the olfactory epithelium. |
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| 09:06 | we don't talk about those because those a little bit more complex and a |
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| 09:10 | bit harder to grasp visual reception and fields in, in the eyes are |
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| 09:16 | so hard to understand. And we about how with, with rods and |
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| 09:21 | , these receptive fields are slightly And the way that you can think |
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| 09:25 | is just, it's that when you um a receptive field, you're really |
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| 09:31 | here at the gang. All So the question you're really asking is |
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| 09:35 | many cells are converging on that ganglion . So if you have a small |
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| 09:41 | field, you'd have a gangle cell you don't have a lot of |
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| 09:47 | right? So in this case, is a very small receptive field because |
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| 09:50 | only have one cone terminating on that ganglion cell, right? So there's |
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| 09:56 | little convergence right here. You'd say is a really broad receptive field. |
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| 10:03 | it doesn't matter if I activate this , it doesn't matter if I activate |
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| 10:05 | cell, that one ganglion cell can activated by all the cells downstream. |
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| 10:12 | I have a broad or a large field. And this receptive field is |
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| 10:18 | ultimately gives us the acuity in our . OK. So remember when you're |
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| 10:25 | forward, is it acute? Are clear? I want, I'm, |
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| 10:32 | remember if it's not go see your , right? Yes, it |
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| 10:37 | All right. So what that tells is that in the phobia in, |
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| 10:40 | should have very, very small, tightly packed receptive fields. But over |
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| 10:48 | it's kind of fuzzy, right? can see this stuff, but it's |
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| 10:51 | crystal clear. So what we have you're moving further and further away from |
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| 10:56 | phob and central, we're gonna have and larger receptive fields. All |
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| 11:03 | it gets the job done, But it's not so clear as what |
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| 11:08 | see when we're straight on. All . So receptive fields are gonna vary |
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| 11:13 | size and they give rise to this of converge or this degree of |
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| 11:18 | Now, sometimes this hits, sometimes misses this slide. All right. |
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| 11:23 | have grown up your entire lives with TV. All right. I grew |
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| 11:29 | with black and white television. Isn't weird? We had a color |
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| 11:35 | But you also had black and white . S remote controls. They didn't |
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| 11:42 | . Not until about 76. I'm can see gray hair stories. I |
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| 11:51 | tell anyway what I like to use help you understand acuity is to understand |
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| 11:59 | evolution of television. The evolution of back until about oh, I don't |
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| 12:06 | , 2000 most TV S were what call standard definition. All right, |
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| 12:11 | definition is 4 80 P. You heard that term 4 80 p and |
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| 12:16 | that refers to it refers to the of pixels that go from the very |
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| 12:21 | of the screen to the very bottom the screen. So you can literally |
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| 12:24 | all the pixels and that's how many are there. And then somewhere around |
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| 12:30 | or so HD became really, really . Now there's multiple definitions of |
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| 12:35 | That's more of a marketing gimmick. stations don't want to use. True |
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| 12:39 | . True HD is 1000 80 So in the same space that you |
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| 12:46 | over here, you're going to have of 480 pixels, you'll have 1000 |
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| 12:49 | 80 pixels. All right. So means the pixels are smaller to fit |
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| 12:55 | that same space. And so that you greater acuity. Would you agree |
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| 12:59 | this is a lot clearer than Yeah. And then the marketing geniuses |
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| 13:04 | the number. So we now have pixels. I think it's 2048 and |
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| 13:09 | call that four K, which is . That should be two K but |
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| 13:13 | K sounds better than two K, it? Yeah. And so now |
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| 13:17 | that same space from top to you now have 2000 plus pixels. |
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| 13:21 | this clearer than that? Yeah. this is an example of having |
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| 13:27 | very small receptive fields, right? receptive field for each of these are |
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| 13:33 | smaller and smaller as we go. as we get smaller and smaller, |
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| 13:38 | terms of receptive fields, we get acuity. Does that kind of make |
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| 13:43 | now? All right. So that's I kind of show that because |
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| 13:48 | that small receptive field is what we in the Phobia cents. All |
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| 13:53 | right there in the very center of retina, that's where the light is |
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| 14:00 | sent. So that the image is , very clear. And as you |
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| 14:03 | further and further away, that's where gonna get those larger receptive fields where |
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| 14:08 | gonna be fewer cells. Um really the better way to do it |
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| 14:13 | there's going to be more cells converging that ganglion cell. So there's fewer |
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| 14:17 | cells in terms of concentration, I'm to briefly explain this, but don't |
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| 14:25 | terribly caught up in it. One the things that you'll see very often |
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| 14:30 | that you'll have within a receptive something that's called a center versus a |
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| 14:35 | or an on or off system. the idea here is again, it |
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| 14:40 | to do with the visual processing that prior to information actually getting to your |
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| 14:46 | to your brain. All right. here we are, what's this cell |
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| 14:50 | here, generically photoreceptor cell, what's cell? What's this one down |
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| 14:58 | Ganglion cell? All right. And we had these weird cells in the |
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| 15:02 | , right? We have a layer and we have a layer here. |
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| 15:04 | one that's here is called the horizontal because they're horizontal, right? The |
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| 15:11 | of the nomenclature, right? What is telling you is like look for |
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| 15:16 | specific receptive field, right? So our receptive field based on the |
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| 15:20 | we actually have two ganglia that are with this one receptive field. But |
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| 15:25 | we have is we can see that receptive field has a center region and |
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| 15:29 | an outer region. And what this field does is that when light hits |
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| 15:34 | receptive field, it hits in the , it activates this cell, which |
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| 15:39 | inhibits and makes sure that this pathway the outside is not activated. So |
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| 15:45 | the only signal that comes in is one that says, hey, uh |
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| 15:49 | center region has been activated and so this does is it creates a perception |
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| 15:54 | greater contrast. Have you ever looked like a, an apple or |
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| 16:00 | You know, just a round object you got that little shiny bit that's |
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| 16:04 | to you, right? You know I'm talking about? Anything that's, |
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| 16:08 | has kind of a, a rounded . Um Here's the rounded surface, |
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| 16:14 | guys see how it's kind of shiny and then it kind of fades away |
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| 16:17 | that. That happens not because the is hitting this and not hitting |
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| 16:22 | the light is hitting this all the . But when that light is coming |
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| 16:26 | and reflecting to you, it's hitting cells like this so that it accents |
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| 16:32 | center and makes the outer portions more so that you can perceive the contrast |
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| 16:40 | those two things. That's what these of receptors fields at. This is |
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| 16:45 | an example of how modulation takes place it gets to the brain. And |
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| 16:52 | have these types of modulation systems that with color, deal with light, |
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| 16:57 | , deal with um black versus white , all sorts of things. So |
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| 17:05 | they're kind of the center versus all right, but I just wanted |
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| 17:10 | just kind of show you that all right, modulation takes place and |
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| 17:14 | doing the modulating? Well, it's place so that I'm activating one gangland |
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| 17:19 | another. That's kind of what I'm to get at. Not likely you'll |
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| 17:23 | a question on this because this is . But I want to show you |
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| 17:27 | eyes are not simple. Optometry. is four years because complex doesn't take |
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| 17:35 | much to learn all the parts of eye. OK. So what I |
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| 17:41 | at the beginning class is we're gonna most of our time talking about photo |
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| 17:46 | um the, the, the visual visual cascade, the visual processing what |
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| 17:53 | looking at in this picture here, can see we have a rod, |
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| 17:56 | the outer segments, you can see little pancake things on the inside. |
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| 17:59 | are the discs, it's these disks all the action in the photoreceptor is |
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| 18:04 | place when we're dealing with the they don't have the disc. It's |
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| 18:07 | the outer membrane folds over itself to these structures that look like discs, |
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| 18:12 | it's the same sort of process. we focus on the rod because it's |
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| 18:16 | . But understanding that the cone kind does the same thing on these |
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| 18:21 | We have a protein that is a transmembrane protein. And we've seen proteins |
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| 18:31 | this over and over and over This is a G protein coupled |
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| 18:38 | Again, Doctor Wayne. Really? , we teach it over and over |
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| 18:44 | because it's everywhere. Now, this is called photo pigment. Now, |
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| 18:51 | whole thing is photo pigment, not the transmembrane protein, the transmembrane protein |
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| 18:57 | called sin. All right. And already bound to its ligand. You |
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| 19:04 | what a ligand is? It's a that activates another molecule. The ligand |
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| 19:09 | is this right here. It's retinol is half of vitamin A. |
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| 19:13 | you take vitamin A, it's this then you just take another one and |
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| 19:16 | flip it over and connect them. what vitamin A looks like. All |
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| 19:21 | . So retinol exists already bound to , which is the weirdest thing ever |
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| 19:25 | this is a G protein coupled receptor aren't supposed to be bound to the |
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| 19:30 | . But this is a system that created to be able to detect |
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| 19:35 | Now sin is uh has the specific amino acids that are, are located |
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| 19:45 | it that are tuned to different wavelengths light. So rods have a specific |
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| 19:53 | molecule, the three cones that we have specific molecules. So we call |
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| 19:59 | sin and, and, and the is called red. The ones that |
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| 20:04 | in cones are photos and, and absolutely imperative that you memorize these |
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| 20:10 | right? What do you think? , of course not. Right. |
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| 20:15 | idea here is just that OK, have three different cones, they have |
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| 20:17 | different wavelengths that they respond to and have different maximal. All right, |
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| 20:22 | don't care that you know, please do not under any circumstances. |
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| 20:26 | your time trying to memorize those. . But you should know that they're |
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| 20:31 | . You're used to calling them green and red. All right. |
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| 20:35 | you probably heard that your blue your red cones, your green |
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| 20:38 | And that's these, these names are poorly used. They're, they're not |
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| 20:44 | . What's better is to use the , which refers to the wavelength of |
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| 20:49 | that they respond to so short, and long. But we're, we're |
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| 20:54 | gonna get all fanciful about that. just rods, there's three different |
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| 20:58 | OK. Now, because there's three types, they respond quite differently to |
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| 21:07 | . And so you'll see usually charts this and notice this chart has a |
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| 21:11 | bunch of different things. It has range in which blue cones are being |
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| 21:15 | , the range in which red cones stimulated, the range in which green |
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| 21:18 | and the range in which rods are stimulated. So notice rods are stimulated |
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| 21:24 | the visual spectrum, right? The are specific portions of the visual |
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| 21:32 | but rods don't play a role in color. The way that we understand |
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| 21:38 | is dependent upon the ratios in which of the different cones are being |
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| 21:44 | Now notice I said ratios, all . So if you look at this |
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| 21:48 | , look at what it says normal or normalized absorbents. So it's |
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| 21:54 | saying absorbing 0% to 100% right? it's basically saying how active is this |
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| 22:01 | cone? And so if I'm being something like blue light. Well, |
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| 22:07 | blue light. Well, what can do is I can go through? |
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| 22:10 | , what did I say up here uh I'm saying 5 60. So |
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| 22:13 | as well use the example I have . So 500 there's 5 55 |
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| 22:18 | So here is my blue cone being at all. What do you |
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| 22:24 | No. So we'd say it's 0% . What about my green cone? |
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| 22:29 | it being stimulated? What do you ? And about I said about 80% |
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| 22:37 | mean, this is eyeballing it. making up numbers, right? Then |
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| 22:40 | go up here again. What about ? Well, red is being maximally |
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| 22:44 | probably about 100%. So our perception this color here, right is this |
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| 22:52 | of greenish yellow. It's kind of into the yellow from green is a |
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| 22:56 | of all three of those cones being in a different in a specific |
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| 23:01 | 0% blue, 100% of the red 80% stimulation of the green. Now |
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| 23:07 | this is not mixing paint. This like going and trying to figure out |
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| 23:12 | pigments I'm using. This is just about how active those cells are and |
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| 23:16 | cells send the signal up to the and said I was activated by this |
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| 23:21 | . So it's the number of action that it's receiving and it's doing it |
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| 23:24 | each of these cones and the brain , OK, well, I got |
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| 23:27 | activation of this 80% and 0%. is this perception. Now, I |
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| 23:37 | you to look, you guys remember old Roy G Biff. You learned |
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| 23:41 | G Bi as a kid, Where on Roy GB? Do you |
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| 23:45 | that color right there? What color that pink? Do you see pink |
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| 23:51 | Rogi yet? Do you perceive Huh? What's going on here? |
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| 24:01 | , this refers to wavelengths. How colors do you think you can actually |
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| 24:07 | Roy G bis? How many colors plus G plus E seven? |
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| 24:13 | Ok. How many colors can you if you had to write dental |
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| 24:17 | How many do you think you can more than seven? I like |
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| 24:22 | Guys are probably I'm gonna ask you , how many colors do you think |
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| 24:25 | can perceive like nine? Because you to put black and white in there |
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| 24:31 | well? Yeah, that's about as as we get, you know, |
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| 24:35 | ladies. How many colors of blue you think up of like eight |
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| 24:42 | Right? Guys are just like it's , right? But how many colors |
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| 24:46 | you think you can actually perceive if had to guess a number, throw |
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| 24:54 | number at me 2000. That's But not enough. 100,000, you're |
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| 25:03 | better. Not enough. Keep She said 500,000, 1.4 million |
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| 25:13 | Some women have 1/4 cone and that goes up to about 14 million. |
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| 25:25 | , can we actually name those No, I'm sure there's somebody who |
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| 25:30 | name those colors. They'll come up like Arctic mist and, you |
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| 25:33 | weird things like that. But the here is that because of the way |
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| 25:38 | cones behave, we get different It's not the question of the |
|
| 25:44 | right? The wavelength matters because that's you're actually using to stimulate. But |
|
| 25:50 | the amount of light that you You know, there's other factors that |
|
| 25:55 | our perception of color. But the I want you to walk away with |
|
| 26:00 | is that red cones don't detect green cones, don't detect green and |
|
| 26:08 | cones don't detect blue, blue cones along a very broad spectrum, red |
|
| 26:17 | , a very broad spectrum and it's degree of activation of each of those |
|
| 26:24 | in combination that matters. OK. women can see colors better than |
|
| 26:31 | but you already knew that. All right. So color blindness is |
|
| 26:38 | result of a missing cone. So they talk about red, green, |
|
| 26:42 | blindness, all right. Let me up here for a second. You |
|
| 26:47 | not need to know this. This here me just throwing information the genes |
|
| 26:53 | encode for those sins. The red the green are basically a duplication, |
|
| 27:00 | ? So whenever you have a gene , that means they do kind of |
|
| 27:03 | same thing. But over time there's mutation and so they become slightly |
|
| 27:07 | This is a completely different gene. so what happens is is when you're |
|
| 27:11 | about red, green, color you're basically knocking out one of those |
|
| 27:15 | and I can't remember which one is . And so what ends up happening |
|
| 27:18 | that you lose. It's basically saying is always zero. So the brain |
|
| 27:24 | perceives the stimulation of that cone because is no cone with that particular |
|
| 27:31 | And so that's why they, they with that. And if you've ever |
|
| 27:35 | the charts of what red, green blindness is, it's not like you |
|
| 27:38 | see red. It's just things the best example would be van |
|
| 27:44 | If you go look at some van pictures, they, they have these |
|
| 27:48 | unique colors to him because he was blind. And so he just painted |
|
| 27:52 | world as he saw it and he those colors and they don't necessarily match |
|
| 27:57 | the world really looks like for those have three coats. And again, |
|
| 28:02 | do people with four cones have? the way, chickens also have four |
|
| 28:05 | . Why they have four cones? have no idea. Dogs have two |
|
| 28:09 | . They can't distinguish between yellow and , which is why if you take |
|
| 28:13 | tennis ball and throw it in the , they have a real hard time |
|
| 28:16 | it. They have to actually see it lands. So if, if |
|
| 28:20 | throw it where they can't see They have to hunt and they have |
|
| 28:23 | sniff it out. It's pretty All right. So this is |
|
| 28:29 | where we want to go is photo , photo transduction is like the mouse |
|
| 28:34 | game, right? It's A to to C to D to E. |
|
| 28:37 | what we're looking at here is the list of all the proteins that are |
|
| 28:41 | here. How big is that It's five proteins. So it's not |
|
| 28:45 | bad as some. All right. what we're gonna see is that |
|
| 28:49 | it's not particularly hard and I'm just walk through. So I'm gonna show |
|
| 28:53 | what your book has and then we're show you how I set it |
|
| 28:56 | All right, because it's easier for to do the animation that way I |
|
| 29:01 | break up the books, photo. right. So over here we have |
|
| 29:07 | molecule, I've gotta make sure I'm at the right thing. It's color |
|
| 29:10 | pink, it's ate cycles gate, job is to take this molecule |
|
| 29:16 | It's just a nucleotide just like a , right? And what it does |
|
| 29:20 | it cleaves off two of the phosphates bends that phosphate around and make |
|
| 29:24 | GMP. So M one T All right. And the C at |
|
| 29:30 | beginning means I've taken it and I've it around, right. So, |
|
| 29:35 | , we have another molecule, we our photo pigment. So there's our |
|
| 29:39 | pigment. Remember it's a G protein receptor. So it's coupled to a |
|
| 29:42 | protein. This was the very first protein ever discovered. So it got |
|
| 29:46 | special name. They call it translucent , oh, it's, it's something |
|
| 29:50 | and interesting. And then they discover all over the place. So we |
|
| 29:54 | a photo pigment, we have All right. When we activate the |
|
| 29:59 | , we're going to activate the transducer is going to activate another molecule called |
|
| 30:02 | dia. Now, there are hundreds phospho dias. So we don't distinguish |
|
| 30:07 | one this is, but a phospho is responsible for taking cyclic GMP and |
|
| 30:14 | that cyclical portion of the bond and it normal GMP. OK. So |
|
| 30:20 | changes its shape and whenever molecules change , they behave differently, we've learned |
|
| 30:25 | , right. OK. The last in our little picture here is we |
|
| 30:29 | this channel, it's called a cyclic gated channel. And really what it's |
|
| 30:34 | you is what binds it cyclic Do we have a cyclic nucleotide in |
|
| 30:38 | little model up here? What's it her? It's right there. Cyclic |
|
| 30:44 | . OK. So cyclic GM P's is to bind up the channel. |
|
| 30:49 | you bind up, the channel opens the channel and things come in. |
|
| 30:52 | right. So, so those are things that we're gonna be looking |
|
| 30:55 | Now we're gonna walk through and we're see how they all work together. |
|
| 30:58 | right, So this is my Again, the colors match what you |
|
| 31:02 | the previous thing. But this is for me to manipulate this picture over |
|
| 31:07 | . So you can see, I've some, some, some things around |
|
| 31:10 | kind of put them in order. your cyclic GMP, here's your photo |
|
| 31:13 | . Here's your transduce, there's a Dira, there's your channel. |
|
| 31:19 | So it's all there. Now, first thing I want you to look |
|
| 31:23 | is what's going on while it's right? We want to ask the |
|
| 31:27 | , what is a photo receptor cell when there's no light? OK. |
|
| 31:32 | this is kind of weird because when think about a cell at rest, |
|
| 31:35 | ? Because dark would be, I'm activating the cell, there's no photons |
|
| 31:40 | . So at rest, I expect cell to be doing nothing. But |
|
| 31:44 | it's doing something. See the gate is active, it's always active, |
|
| 31:51 | always turned on. So it's always GTP and it's always making cyclic |
|
| 31:57 | So I got lots and lots of GMP inside the cell. The more |
|
| 32:01 | GMP I have the greater chance it's to find and bind to the channel |
|
| 32:06 | open up the channel if I open the channel sodium comes into the |
|
| 32:11 | And so I end up with a of sodium inside the cell. If |
|
| 32:13 | have a lot of sodium inside the , what do I say? The |
|
| 32:16 | is? If I have sodium flowing a cell, it's depolarizing. So |
|
| 32:24 | the dark, my photoreceptor cells are . And when I have depolarizing |
|
| 32:30 | what are they doing? You if it's a neuron, it's releasing |
|
| 32:34 | message. And so that's what your receptor is doing in the dark, |
|
| 32:40 | active and it's signaling to the bipolar . Now, if you've been paying |
|
| 32:47 | at all, you know, that cells are downstream of and are being |
|
| 32:52 | by these photoreceptor cells. And you're wait a second. But I see |
|
| 32:56 | the light, I don't see in dark. You're telling me that my |
|
| 32:59 | cells are active in the dark. , it's backwards to what you would |
|
| 33:07 | . I'm not activating it by I'm gonna be turning off my cells |
|
| 33:11 | the light. Now, why do do that? It's a biology |
|
| 33:17 | The biggest biology problem is always how I make a cell most efficient in |
|
| 33:21 | of energy consumption? There's more We are not nocturnal creatures. We |
|
| 33:27 | creatures of light. And if I to see in the light, I |
|
| 33:31 | to use less energy. So it's dark. I use the energy. |
|
| 33:35 | flipped it all around. OK. in the dark, I'm always making |
|
| 33:42 | GMP I'm opening up my channels. is coming in. I'm depolarizing the |
|
| 33:49 | . When I depolarize the cell, cell is active. All right. |
|
| 33:53 | step one. Now, this is we've never talked about because reasons, |
|
| 34:01 | don't know why we don't ever teach part to you. All right. |
|
| 34:04 | if sodium work to constantly flow into cell, would equilibrium ultimately occur. |
|
| 34:10 | do you think if you're trying to up a glass, will it eventually |
|
| 34:14 | up completely? So, if sodium always flowing in the cell during the |
|
| 34:18 | , you'd expect the cell to fill with sodium and then it wouldn't be |
|
| 34:20 | to do anything. Well, that true. That's what would happen. |
|
| 34:24 | what we do is in order to that there's always sodium flowing in the |
|
| 34:29 | in the dark, we have to a current, we have to remove |
|
| 34:31 | out of the cell. This is is referred to as the dark |
|
| 34:34 | So we have our channels open, is going in sodium flows into the |
|
| 34:39 | . We need to get rid of sodium. So we got to pump |
|
| 34:41 | out. We're going to use the potassium A TPS pump. Have we |
|
| 34:44 | this one before? Yeah. So means we pump potassium in. |
|
| 34:48 | we want potassium to escape because if much potassium comes in, well, |
|
| 34:53 | we won't be able to pump the out. So we have leak channels |
|
| 34:57 | allow the potassium to leave. And what happens is is sodium is constantly |
|
| 35:01 | flow. So in the dark, creating this depolarization and you're making sure |
|
| 35:07 | it stays depolarized because of the dark . OK. So that's all the |
|
| 35:13 | current is it ensures that sodium can into the cell. But we don't |
|
| 35:18 | about the dark. Do we? wanna know how we see things? |
|
| 35:23 | how do we see things? this is where light comes in. |
|
| 35:29 | here you can see up there at top. I got a little photon |
|
| 35:33 | comes zipping into your eyes. It zipping through the ganglion cells, zipping |
|
| 35:37 | the bipolar cells hits one of these cells finds one of these discs. |
|
| 35:42 | . There's a photo pigment inside the pigment part of that is retinol. |
|
| 35:47 | a photon comes along and hits that molecule. Now retinol exists bound to |
|
| 35:54 | pigment in the CS configuration. I'm flip the slide real quick. So |
|
| 35:58 | can see what I'm talking about. right. So in the dark, |
|
| 36:02 | is what retinol looks like. All , it's in the 11 confirmation. |
|
| 36:07 | if you were to count up the , that would be the 11 |
|
| 36:10 | And so you can see the tail kind of crooked like. So |
|
| 36:13 | if you go back and look at picture, see I even drew, |
|
| 36:19 | it's a crooked little tail up See what that photon is. |
|
| 36:27 | it's a packet of energy and that converts that bond, it twists it |
|
| 36:33 | that it moves it from this 11 into this all transformation. You ever |
|
| 36:39 | why you take organic chemistry so that understand those words that I just told |
|
| 36:44 | that is the only reason it is vocabulary class so that you can do |
|
| 36:48 | in your biology classes. Do not the chemistry department. I said |
|
| 36:52 | Mhm. All right. Now, we've done here is if you can |
|
| 36:58 | I have in my hand, this the molecule in there. I have |
|
| 37:03 | little tiny cys confirmation of retinol. I change the shape of the |
|
| 37:09 | what have I done to the shape the receptor? I changed it. |
|
| 37:18 | , no, I mean this, , I've straightened but I've changed the |
|
| 37:21 | when I change the shape of a . What happens? I change its |
|
| 37:27 | . So here we already have the in place, but it's an inactive |
|
| 37:32 | . What we've done is we've activated ligand through the adding of that energy |
|
| 37:36 | changing the shape of that tail. now what we've done is we've activated |
|
| 37:42 | photo pigment. OK. Now, we said that we have different photo |
|
| 37:47 | and different cells. So they're gonna attuned to different wavelengths of light which |
|
| 37:50 | different, different energy forms, but doesn't matter which one we're looking |
|
| 37:54 | they all do the same thing. here, what we're doing is we |
|
| 37:58 | activated our molecule. Now, once activate the, the retinol to |
|
| 38:05 | to transform, we've got to go uh fix it. So when I |
|
| 38:09 | about bleaching your eyes, you bleaching these receptors. That's really what's |
|
| 38:13 | on is we've kicked that bad boy and we got to change it back |
|
| 38:16 | its original shape. We'll get to in a moment. What we're focusing |
|
| 38:19 | now is if I activate a I have to activate the G |
|
| 38:23 | Right? So the change in the here because of the change in the |
|
| 38:27 | here is normally bound up to this . This GDP and it says, |
|
| 38:32 | , I'm no longer attracted to kick you out and I've created a |
|
| 38:35 | binding site that act that is attracted GTP. Now, G protein is |
|
| 38:41 | GTP ace, meaning it breaks the in that last phosphate releases the energy |
|
| 38:46 | it can go do stuff. And what we're doing here is by taking |
|
| 38:51 | energy here, changing the shape we're changing the shape here so that |
|
| 38:54 | can activate that. And so it that GTP and says, all |
|
| 38:59 | I'm off to do something. What I do? Well, the alpha |
|
| 39:03 | , remember G proteins have three Remember way back when we talked about |
|
| 39:07 | they're hetero trime, there's an alpha a beta gamma. Some people are |
|
| 39:11 | in their heads, the rest. going crap. I need to go |
|
| 39:13 | and look at my notes, But that alpha goes on and it |
|
| 39:19 | that phospho dia and when it finds phosphor Diaa, it uses the energy |
|
| 39:25 | in that GTP to turn on the . So that's what it's doing. |
|
| 39:31 | taking that long and says, all , I've got my GTP with the |
|
| 39:34 | . Let me find the phospho. , there you are. I |
|
| 39:37 | hang out over here. I break energy and say, hey, you |
|
| 39:39 | my energy and you're like, sure, I'll take the energy and |
|
| 39:42 | you take the energy and then what energy does is that it activates the |
|
| 39:51 | estates. And so you start breaking the cyclic GMP. Remember we're making |
|
| 39:56 | GMP, but we start breaking it as fast as we can make it |
|
| 40:01 | not faster. So the inside of cell you start losing the number of |
|
| 40:06 | GMP available, less cyclic GMP less available to open up the channel. |
|
| 40:11 | the channel doesn't have cycle GMP to it up, it closes. If |
|
| 40:16 | channel is closed, sodium can't come . We still have a pump. |
|
| 40:20 | pumping out that sodium as fast as can. So the levels of sodium |
|
| 40:25 | the cell go down if sodium is inside a cell, what do we |
|
| 40:31 | that? What do we call the ? If it's depolarizing if I get |
|
| 40:36 | of sodium, huh. He had polarization. So now the cell is |
|
| 40:41 | polarizing and it's no longer sending a . So in the dark, I'm |
|
| 40:49 | and I'm releasing chemical message in the . I'm hyper polarizing and I'm not |
|
| 40:55 | a chemical message that was five or slides just to kind of walk through |
|
| 41:02 | steps. This is a summary slide put it all in perspective right here |
|
| 41:07 | am in the dark. Here I in the light, you can see |
|
| 41:09 | dark because it's darker, right? it just says everything that we did |
|
| 41:13 | the dark. What is our Right. Well, you can see |
|
| 41:17 | dark current moving along but basically say in the CS form as far as |
|
| 41:20 | is concerned. That means the sodium are going to be open because I'm |
|
| 41:25 | making that cyclic GMP. So the membrane depolarizes and when that membrane |
|
| 41:31 | it's going to cover the entire So that even down here that we're |
|
| 41:36 | depolarization that causes the release of a . That neurotransmitter is stimulating the |
|
| 41:42 | Now, how is it stimulating the ? Well, what we're releasing the |
|
| 41:46 | means go, sorry, if you're , green means go. So I'm |
|
| 41:50 | an inhibitory neurotransmitter. I'm preventing the cell from firing. So in the |
|
| 41:57 | , I see dark because I'm not a signal down to the ganglion |
|
| 42:01 | I'm preventing the signal from moving And so if I'm blocking my bipolar |
|
| 42:09 | , no activation. In contrast, do I have? I got the |
|
| 42:15 | retinol right? Light came along, the shape of the retinol in the |
|
| 42:21 | . I basically chew up on my GMP that means the channel is |
|
| 42:24 | That means I no longer have sodium into the cell. It means my |
|
| 42:27 | is hyper polarized that covers the entire . So I no longer release this |
|
| 42:33 | neurotransmitter. Two wrongs don't make a but three wrongs make or three rights |
|
| 42:39 | a left. I don't know something that. Um No, but it's |
|
| 42:42 | if I say if I have a negative, right? You learn this |
|
| 42:46 | math, two negatives equal a right? And so as we |
|
| 42:50 | we have no inhibitory neurotransmitters, so negative. So what we're doing is |
|
| 42:54 | saying do not release the inhibitory So that means a cell right here |
|
| 43:00 | depolarize and it does so on its , it kind of behaves kind of |
|
| 43:04 | these cells do where it's not the that causes them to fire. They're |
|
| 43:09 | a natural state of wanting to It's when you stimulate them that they |
|
| 43:14 | firing. So it's the same sort thing here. This will naturally start |
|
| 43:19 | . So the gangly un cell downstream activated. So you perceive light. |
|
| 43:26 | it's backwards how weird. But this energy efficient. Keep the cell |
|
| 43:38 | inhibit the downstream cell. The cell polarizes, that allows the downstream cell |
|
| 43:46 | become activated. And I perceive light the signal goes from the bipolar cell |
|
| 43:52 | the ganglion cell, from the gangle up to the visual cortex, which |
|
| 43:56 | get to here in just a I think this slide is just |
|
| 44:02 | It talks about, oh, I why I have it here. So |
|
| 44:05 | talk about adaptation that there is a adaptation. The process of adjusting to |
|
| 44:10 | light intensity, right? This idea oh, if I go into a |
|
| 44:15 | space, it's gonna be hard to because I have to re uh fix |
|
| 44:22 | , or readjust or modify those trans , turn them back into cyst |
|
| 44:28 | All right. And then as far light adaptation, it's basically, |
|
| 44:31 | I've got lots of light. my cones can do this quickly, |
|
| 44:35 | I still have to change all that back into its form. All |
|
| 44:39 | So visual adaptation is simply moving between two states a long time ago and |
|
| 44:46 | , I'm going down a tangent. really shouldn't. Um There was a |
|
| 44:50 | um I'm not even forgetting what it's it's called. Uh But basically, |
|
| 44:57 | , it was uh it was oh Mythbusters, that's what it's |
|
| 44:59 | You guys are not familiar with right? They did an episode on |
|
| 45:03 | do pirates wear ma or wear And the, the hypothesis is is |
|
| 45:09 | they were patches because you're dealing with dark adaptation issue, right? So |
|
| 45:13 | swing across to the ship, you to go in and you wanna |
|
| 45:16 | you're gonna fight on the, on the upper decks where it's |
|
| 45:19 | really light. But then you have work your way down in the lower |
|
| 45:22 | and it's really hard to see in lower decks because one, there's no |
|
| 45:25 | and two, you're used to being in the light. And so it'd |
|
| 45:28 | really, really pitch black. So they think is that some pirates would |
|
| 45:32 | one eye so that it would stay , adapted and the other eye would |
|
| 45:35 | light adapted so you could be outdoors all what you needed to do. |
|
| 45:40 | when you went downstairs, you just up the patch and then now you |
|
| 45:43 | see well in the dark and they to see if this was true and |
|
| 45:48 | created some sort of obstacle course and were actually able to see all the |
|
| 45:53 | they need to do in the You know, it was very, |
|
| 45:55 | dim. So there was light. if they didn't have the patch, |
|
| 45:59 | couldn't see anything. But when they the patch, they could. So |
|
| 46:01 | , oh, this is really Also, chick stick scars and patches |
|
| 46:05 | cool. So, um anyway, what I'm trying to get at here |
|
| 46:11 | that when we go through this we need to recycle that retinol. |
|
| 46:17 | so this is what is called the cycle. Now, there is a |
|
| 46:21 | of information in here. Please, , please do not memorize all the |
|
| 46:25 | . What I want you to understand that when we release that retinol, |
|
| 46:29 | that retinol, it has to go to the pigmented epithelium. Now, |
|
| 46:34 | pigmented epithelium? Well, remember it all the light. So it creates |
|
| 46:37 | dark environment. And then what you do is you can go through all |
|
| 46:40 | steps and you can re twist that back into that cyst form. And |
|
| 46:44 | what you do is you bind it and then you carry it back to |
|
| 46:47 | cell and then you load it back into the retinol. So now it's |
|
| 46:53 | you can use it again, cones actually do this internally, but rods |
|
| 46:58 | . And so one of the reason are slow is because it's dependent upon |
|
| 47:01 | pigmented epithelium. It takes about 10 to get full adaptation for a |
|
| 47:07 | It takes about three minutes. And , you can go and test this |
|
| 47:11 | , go stand outside and then go a dark space and see how long |
|
| 47:14 | takes for you to see clearly in dark space and then do the |
|
| 47:18 | go out into a bright space and how long it takes for you to |
|
| 47:21 | being able to see clearly in the . And you'll find that this is |
|
| 47:25 | lot quicker. It's because the cones a lot quicker. So the visual |
|
| 47:31 | simply is taking that trans retinol and it back into the cyst form. |
|
| 47:39 | right, rods need to use the epithelium. Cones will use the pigmented |
|
| 47:44 | , but they can also do it . Now, as far as the |
|
| 47:51 | pathway is concerned, where is the going? All right. So remember |
|
| 47:55 | , I'm turning off the photoreceptor cells activates the uh bipolar cell. We're |
|
| 48:01 | talking about the on off system because gets confusing. But the bipolar cell |
|
| 48:05 | activate a ganglion cell that ganglion cell produces an action potential that's going |
|
| 48:11 | And what it's gonna do is those travel along the optic nerve. And |
|
| 48:17 | can see that that signal is going be split between the two sides. |
|
| 48:22 | you have the medial sides are always to go to the opposite side. |
|
| 48:27 | you can see over here here is lateral, the lateral comes and stays |
|
| 48:32 | the same side. But over the medial which matches up is going |
|
| 48:37 | cross over and go to the opposite . So each eye is sending signals |
|
| 48:43 | both sides of the brain. We have the optic cos this is |
|
| 48:48 | the crossing takes place, right? it helps us to be able to |
|
| 48:53 | that binocular vision. So our visual is basically creating depth because of the |
|
| 49:01 | of our eyes and how we cross information to both sides. That information |
|
| 49:07 | on into the thalamus. We talked where it goes, it's the lateral |
|
| 49:10 | nucleus, right? Where does the go, medial geniculate nucleus? All |
|
| 49:17 | . And then you get some processing takes place there, the signals get |
|
| 49:22 | up. But the first place that's go is gonna be the primary visual |
|
| 49:26 | . So notice both side of the are dealing with that vision. |
|
| 49:34 | incredibly complex stuff that's going on I don't want you to focus heavily |
|
| 49:39 | what what all these things are. have different types of cells, we |
|
| 49:43 | parvo cells that deal with spatial Color. I love the terms |
|
| 49:48 | So color is is processed in areas blobs. And then the space in |
|
| 49:54 | the blobs are the inter blobs. mean, so that's part of part |
|
| 49:58 | the reason why I just throw, those things at you. I'm not |
|
| 50:01 | be asking how these things are I've looked at these maps and remember |
|
| 50:06 | studied biology for a long time and look at these things and it's just |
|
| 50:10 | uh I, I don't understand because just don't have the the bandwidth to |
|
| 50:17 | the stuff that they what they're All right, if I had |
|
| 50:21 | I could probably spend some time. usually I get really bored very quickly |
|
| 50:24 | start thinking about cartoons I used to . And uh when I was like |
|
| 50:28 | years old, I'm showing this also you because remember what I said about |
|
| 50:32 | cortex that there's six layers and the has depending on where you are have |
|
| 50:38 | layers. So this just kind of you there are those six layers and |
|
| 50:41 | have different densities. And so each these different layers, you can find |
|
| 50:45 | things. And so this is kind showing you that map. So this |
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| 50:50 | layer four. And over here they're you where the magnocellular cells are |
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| 50:55 | which play a role in black and contrast. And over here, they're |
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| 51:00 | to show you where the parvo cellular are located up there in layers two |
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| 51:04 | three. All right. I'm not ask you what layers of these things |
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| 51:09 | in because I'm not gonna remember All right, I just want you |
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| 51:12 | understand that we're taking that visual information we're not like creating film in our |
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| 51:20 | . Everything we see gets broken down its subsequent parts, the contrast, |
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| 51:25 | colors, the form movement function, that stuff is broken down and it's |
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| 51:31 | to all these very weird places. not going to ask you what is |
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| 51:35 | four responsible for? This is trust me, it's complicated slide. |
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| 51:42 | . So this is just trying to you look. So V one, |
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| 51:45 | your visual map that just tells you the light's coming from, right? |
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| 51:50 | if light's hitting this portion of my , it's a specific portion of my |
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| 51:55 | that's being stimulated over here in V kind of how we talked about M |
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| 51:59 | . Do you remember how we talked M one, the motor uh homunculus |
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| 52:03 | the motor cortex? How it has specific organization, visual cortex maps to |
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| 52:09 | retinas. All right. So that's your brain knows where information is coming |
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| 52:14 | . So if you actually get a retina or if you get a wrinkle |
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| 52:19 | your retina, that's why you just sick all the time because your brain |
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| 52:22 | trying to process information because it expects to be coming from this particular |
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| 52:28 | It means it's in this part of retina. And if your retina |
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| 52:31 | your brain doesn't know how to deal that. V two visual memory V |
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| 52:37 | processing motion, object orientation. It's spatial positioning color. That's the blob |
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| 52:45 | V five perception of motion. Some if you're ever interested, look up |
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| 52:52 | see how they figured some of the out. They had to take cats |
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| 52:55 | they started doing stuff to their brains then they would do movement and they're |
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| 53:01 | , oh look, the brain is active. So, so that's vision |
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| 53:08 | I spent an hour on that just catch us up. Are there questions |
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| 53:14 | visual transduction, the depolarization versus hyper , the things in the pathway? |
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| 53:25 | . Questions about how he perceived No. How many colors can we |
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| 53:34 | ? 1.4 million? And if you to Home Depot, you'll see all |
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| 53:39 | different names that people have come up . Literally green, green, |
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| 53:45 | red, red, red. I'm guy. There's eight colors plus black |
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| 53:51 | white. Let's get to the ok? With the ear, we're |
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| 53:57 | with two different things we're hearing and . There's three parts to the |
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| 54:01 | the part of the ear that you of is the outer ear, the |
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| 54:04 | ear, we have the middle If you take your finger, you |
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| 54:07 | can't reach it because that's still you stick your finger and jam it |
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| 54:10 | there, that is still external ear then the middle ear is where we're |
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| 54:15 | going to be transmitting information. So what all this stuff is. And |
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| 54:19 | what we're gonna do is we're gonna a little tiny membrane and then we |
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| 54:23 | into the inner ear. The inner is represented by this structure here. |
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| 54:28 | right, there's actually two different apparatuses . One that's for hearing, one |
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| 54:31 | for balance. We have the the cochlea looks like the snail. |
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| 54:36 | what cochlea means. Snail shell. that look like a snail shell? |
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| 54:40 | is like an alien snail. You see it has all this weird stuff |
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| 54:43 | on. So this right up this is the vestibular apparatus collectively that's |
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| 54:48 | vestibular apparatus and it's there where equilibrium , is is detected. So, |
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| 54:55 | balance or equilibrium and that would be inner ear. Now, this structure |
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| 55:00 | gonna be hard on the outside on the inside, it's fluid on |
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| 55:04 | inside. All right, we'll get all this structure. What we need |
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| 55:07 | do is we need to walk through quickly through the external ear. So |
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| 55:10 | , that weird looking thing on the of everyone's head that is called the |
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| 55:14 | . You'll also hear the word pea . Sometimes I encourage you to find |
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| 55:18 | and look at their ear for a while and look how weird it |
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| 55:21 | It is a weirdly structured. It like an old desiccated apricot. All |
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| 55:28 | . Stairs. Look at somebody's ear a little bit. You'll see. |
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| 55:31 | like, oh my goodness. It . It's weird. It has these |
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| 55:34 | and bumps and it doesn't make any . It's basically cartilage covered with skin |
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| 55:38 | its job is to direct sound to auditory canal. All right, or |
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| 55:44 | ear canal. That's what you'd probably it. This is referred to as |
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| 55:48 | uh uh the external auditory or external meatus. So it's not me. |
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| 55:54 | a me a I said, meet for years and someone finally correct me |
|
| 55:58 | , look at what an idiot you . Yeah, that's true. I |
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| 56:01 | . All right. And what this is it takes a sound and it |
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| 56:05 | that sound to the last structure with , which is the Timpani membrane which |
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| 56:08 | call your ear drum. So tim and it's basically a membrane that separates |
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| 56:14 | external ear from the middle ear. sand waves hit it, it vibrates |
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| 56:17 | the frequency at which the sand waves are hitting it. Now inside the |
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| 56:21 | auditory me. Uh we have um a sermon glands. Um, we |
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| 56:27 | , as I say, yeah, , well, some hairs and those |
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| 56:31 | kind of point this direction and it things from working their way down into |
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| 56:35 | ear. So basically keeps the canal , mostly clear every now and then |
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| 56:40 | have to get a Q tip and that stuff out. Um Just |
|
| 56:43 | you know, if you, there's different types of ear wax and |
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| 56:46 | it's actually genetically determined. So you have dry ear wax or you might |
|
| 56:50 | wet ear wax. You notice I mean that your ear wax is |
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| 56:55 | of those two types dryer and that's determined by your genetics. And I |
|
| 56:59 | remember is there's Asian is one and like uh Eastern European and Africa is |
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| 57:06 | the other. Let's see it All right, moving inward, we |
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| 57:11 | the middle ear. So this is referred to as a Timpani cavity. |
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| 57:16 | region right in here. This is you're gonna see three bones and a |
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| 57:20 | of muscles. We have three 123. And what this does is |
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| 57:24 | takes that vibrating, they're connected to timpani membrane as the timpani membrane |
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| 57:28 | it causes the bones to move and transferring and amplifying those sound waves. |
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| 57:35 | we have the uh maus the incus the staples they're named for what they |
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| 57:40 | like. So it's basically the the anvil and the hammer. So |
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| 57:45 | Anvil syrup is the order in which go through. And just behind the |
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| 57:49 | is a, a structure, it's membrane that goes to the interior called |
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| 57:53 | oval window. And so what you're is you're transferring the vibration of the |
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| 57:58 | membrane to the oval window so that vibrating at the same frequency. But |
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| 58:03 | the oval windows, you have fluid so you need to amplify that frequency |
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| 58:10 | that you can make the fluid inside structure vibrate. There's two muscles in |
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| 58:17 | . One is called the tier One is called the Sted. And |
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| 58:20 | job is to modify the movement of uh bones ever been to a concert |
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| 58:29 | been to a concert uh picked right in the front, in front of |
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| 58:31 | marshall stack. Yeah, the guy out hits that first riff and what |
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| 58:38 | you do? Right. That's, actually a reflexive response to protect the |
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| 58:46 | . Right now, these muscles are to contract to diminish the amplification that |
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| 58:53 | seeing from here to here. So you have really, really loud |
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| 58:56 | they constrict so that the bones don't quite as much, but they're a |
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| 59:01 | slow. And so it takes a bit of time for them to |
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| 59:05 | So you can actually damage your And so part of the reflex is |
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| 59:10 | prevent that. But over time notice a concert doesn't sound so loud. |
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| 59:13 | the, you know, a couple minutes right now it's just big |
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| 59:18 | Right. And you can sit there bang your head or whatever it |
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| 59:20 | Sing along with Taylor. I don't . I had a friend go to |
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| 59:26 | concert. She dressed up to the nine yards, uh, different types |
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| 59:34 | deafness. Yeah. And I'm, be honest, I won't be able |
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| 59:39 | , to identify all the different I'll show one type. All |
|
| 59:43 | But really if there's damage here, can bypass. That's what the cochlear |
|
| 59:49 | is, right? It's basically bypassing . But if there's damage to the |
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| 59:55 | inside the cochlea that do the that's a lot harder to fix. |
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| 60:01 | then there's also nerve damage that you do. All right. So we |
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| 60:06 | the bones, got the muscle. then you see down here we have |
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| 60:09 | tube, we call it the but they are now starting to call |
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| 60:13 | the auditory tube because people's names are or something. Um, but the |
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| 60:18 | here is this allows this space to equilibrated to the external environment. Anyone |
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| 60:24 | ever popped your ears before like right. What are you doing? |
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| 60:29 | , you're using your jaw muscles to of spread open the, the |
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| 60:33 | And now what you're doing is you're the air behind the timpani membrane with |
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| 60:37 | air in front of the Timpani If you've ever played with a |
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| 60:41 | if you, if you create pressure the membrane of that drum. It |
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| 60:46 | a less uh less vibrating sound. other words, it's, it's |
|
| 60:53 | And if you've ever had a clogged , right. You know, you're |
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| 60:55 | taking off in an airplane, go different altitude, you'll start noticing, |
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| 60:59 | feel the pressure build up and you'll that it's harder to hear. It's |
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| 61:03 | the tian membrane isn't vibrating so So what do you do? You |
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| 61:07 | your ears? If that doesn't you can always do this. All |
|
| 61:14 | . And if it's a little kids on airplanes carry lollipops because they suck |
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| 61:19 | those. And it does the same . Just a little trick for your |
|
| 61:25 | . Dumb dumbs are your friends, dummies? Dumb dumps. All |
|
| 61:32 | Moving to the inner ear. This where all the action is taking |
|
| 61:35 | All right. So I said on outside, it's bony on the |
|
| 61:39 | We have kind of a soft gooey . It's really a membranous labyrinth. |
|
| 61:43 | picture does not show this. This is showing you the bony portions. |
|
| 61:47 | right. So what we said is have the cochlea. All right. |
|
| 61:50 | we have this vestibular apparatus. You see it actually has two parts to |
|
| 61:54 | . It has this region down which is not being labeled. This |
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| 61:58 | is called the vestibule. All if you go to somebody's house, |
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| 62:02 | is the vestibule right inside the open , that's where you greet people. |
|
| 62:11 | . So that's the vestibule. All . And then you see 123 |
|
| 62:16 | these are called the semicircular canals because are semi circles. All right. |
|
| 62:28 | what we're saying. All right. that's on the outside. Now, |
|
| 62:31 | is fluid inside these and what it , it's called para limp. And |
|
| 62:35 | very similar to the interstitial fluid. . Where interstitial fluid is between cells |
|
| 62:42 | these structures. You're going to see membranous material and inside the membranous |
|
| 62:48 | There is another fluid, it's called , which is very similar to intracellular |
|
| 62:52 | . All right. So kind of are kind of backwards here. |
|
| 62:56 | if you look at the three so in the cochlea, we have |
|
| 62:59 | cochlear duct in the vestibule, we a couple of organs, one is |
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| 63:04 | the uomo saccule. And then we the semicircular canals, we have the |
|
| 63:09 | circular ducts and it's these structures where gonna find the receptors for the different |
|
| 63:17 | that the ear is doing. So cochlear duct is responsible for hearing. |
|
| 63:21 | has an organ within it called the of corti. Um They also call |
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| 63:25 | the spiral organ. I have to to use the new nomenclature because |
|
| 63:31 | but these two things are for And what we're gonna do is we're |
|
| 63:34 | look at sound. First, we're look at how we detect sound through |
|
| 63:38 | spiral organ or, or or organ corti now notice here this, I |
|
| 63:43 | want to show you this when we you the uh uh electromagnetic radiation, |
|
| 63:47 | had those two weird wavelengths right This is the wave that you're more |
|
| 63:52 | with. So it looks like a little sine wave. What we're looking |
|
| 63:56 | here is that when you make what you're doing is you're causing air |
|
| 64:00 | or molecules in the air to compress to expand. it's called rare faction |
|
| 64:04 | compression, compression, rarefaction, rare faction. So you can see |
|
| 64:10 | , here's the compression, there's a faction and it matches up with the |
|
| 64:14 | sound waves in order to make I'm producing, I use energy. |
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| 64:18 | so I'm making that energy cause those to move. When those molecules hit |
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| 64:23 | molecules, they lose a portion of energy. And so sound dissipates the |
|
| 64:28 | and further away it gets from the of origin, right? So when |
|
| 64:33 | loud, everybody can hear me, when I whisper, right? Because |
|
| 64:41 | the amount of energy that's being Here, sound is characterized by both |
|
| 64:45 | and intensity. You heard the intensity loudness that's measured in decibels, that's |
|
| 64:50 | log scale. So as you go every 10, you're, you're going |
|
| 64:54 | significantly. When we're talking about we're talking about pitch, that's high |
|
| 64:59 | and low notes. All right. high frequencies, high notes, low |
|
| 65:04 | , very white. OK. You know who Barry White is. I |
|
| 65:10 | realized that. All right, here are. We're taking a slice through |
|
| 65:18 | cochlea. Whenever I make a reference that, you should probably add it |
|
| 65:26 | the list of things I need to up on youtube. OK. Barry |
|
| 65:30 | , who's Barry White? So here's cochlea, we're taking a slice through |
|
| 65:37 | . So you can see there's ring one, ring, number two, |
|
| 65:39 | just keeps dying up. So here's ring, there's a ring and then |
|
| 65:42 | just keeps going up. So you're spiraling upward. This is the cochlea |
|
| 65:47 | . So you can basically imagine I'm up all the way around and then |
|
| 65:50 | reach an apex, we call this helicotrema and then when I come back |
|
| 65:54 | other direction. So here is the window there, you can see your |
|
| 65:58 | . And so we have this one that's going all the way up. |
|
| 66:02 | , zip, zip, zip helima back the opposite direction. So we |
|
| 66:07 | names for these tubes, the tube the oval window moving up towards the |
|
| 66:13 | that's called the scala vestibule. So vestibular duct, that's that one, |
|
| 66:18 | go all the way up to the , come back around, you're now |
|
| 66:21 | the scala timpani. So here's the tim pan, all right, the |
|
| 66:26 | duct and then in between those, is where we see those two |
|
| 66:31 | So there's a membrane there and a there, you can see the two |
|
| 66:35 | . So those membranes creates a duct between them. And that's what you're |
|
| 66:39 | here. Notice this duct is closed itself. So we have the oval |
|
| 66:45 | , scala, tiny helima scala. then over here we have the round |
|
| 66:51 | . So oval window, first round . Second way you can think about |
|
| 66:54 | . If you ever play with one those stress stress ball stress toys. |
|
| 66:57 | like a little clown face and you the little eyes open, you know |
|
| 67:01 | I'm talking about. OK. So I put pressure here, that pressure |
|
| 67:05 | going to go all the way around it's gonna be absorbed over here at |
|
| 67:07 | round window. What we're interested is on here. So this membrane that |
|
| 67:16 | up the roof of the middle duct the cochlear duct is called the vestibular |
|
| 67:22 | . So the floor of the vestibule the vestibular membrane, the roof of |
|
| 67:29 | timpani duct or what we call the of the cochlear duct is called the |
|
| 67:33 | membrane. All right. And these membranes, they're, they're movable, |
|
| 67:37 | ? They're soft. And so you think about it like this. |
|
| 67:40 | they sit like that. So up , vestibular membrane down here, basilar |
|
| 67:46 | , OK? Basler sorry, Basler right now. All I've done is |
|
| 67:52 | just painted what these structures are. the action that we're interested in is |
|
| 67:57 | to be taking place here inside that duct. So we need to come |
|
| 68:01 | take a closer look at the cochlear . All right, this is the |
|
| 68:05 | of this is what allows you to sound. All right now inside. |
|
| 68:12 | you can see we have this structure inside that cochlear duct. This is |
|
| 68:17 | organ of cord itself pulled out. it's this stuff right here pulling |
|
| 68:20 | So it's nice and big. What can see is we have a series |
|
| 68:23 | hair cells. All right, the cell is what actually detects hearing or |
|
| 68:29 | is the organ of hearing. This the structure that detects sound waves. |
|
| 68:34 | have this stiff membrane that stiff sits top. So it kind of sits |
|
| 68:40 | in the middle. So if you these two, it kind of sits |
|
| 68:42 | in between them. It's called the membrane. It's kind of like a |
|
| 68:46 | board, very, very stiff. right. So it doesn't move a |
|
| 68:51 | . The other two can move and we have nerve fibers that join together |
|
| 68:56 | they form a larger structure. This called the um spiral ganglia. They |
|
| 69:03 | the cochlear branch of the spinal Now, let's go through these one |
|
| 69:08 | a time. What is the hair ? These are mechanical receptors they have |
|
| 69:11 | their surface, the Stoia. So not true CIA, they're modification, |
|
| 69:16 | very, very stiff and they're actually to each other. The front one |
|
| 69:21 | sits over here that's called the And then you have a series of |
|
| 69:25 | CIA that move away from it. so what they're going to do is |
|
| 69:28 | going to be able to move back forth. We have one cell that |
|
| 69:32 | by itself. So you can see up there at the top of the |
|
| 69:35 | that's been colored yellow, that is single inner hair cell. So there's |
|
| 69:40 | whole row of them and it just in and out of the, of |
|
| 69:43 | picture as we're looking at them and we have the outer hair cells, |
|
| 69:47 | outer hair cells are 12 and then be a third one right there. |
|
| 69:51 | what these are the outer hair The inner hair cell is responsible for |
|
| 69:55 | movement of this fluid and ultimately is one that serves as the sensory |
|
| 70:02 | These three modify the movement of the . All right. So in other |
|
| 70:08 | , this modifies uh the the movement that we can modify how we perceive |
|
| 70:14 | . This is actually detecting the movement . So the inner hair cell is |
|
| 70:19 | detector. So how does this all ? We gonna be up here? |
|
| 70:24 | I'm gonna use the unwound picture. right. So when a sound wave |
|
| 70:31 | , it hits the penny goes through external auditory me Metu hits the timpani |
|
| 70:37 | . The timpani membrane vibrates at the of that pitch of whatever that sound |
|
| 70:43 | , right? So it's just think someone pressing a button on an organ |
|
| 70:48 | right that creates a pitch causes causes timpani membrane to vi vibrate, |
|
| 70:54 | causes the malis to vibrate the incus vibrate and the staples to vibrate. |
|
| 71:00 | what it's gonna do is it's gonna the oval window to vibrate at the |
|
| 71:04 | frequency. But because I have fluid that I need to amplify. And |
|
| 71:10 | the purpose of those bones is to the, the frequent or not the |
|
| 71:15 | but the loudness to make it more . All right. Now I'm gonna |
|
| 71:20 | something dumb here. But I want to visualize. Have you ever uh |
|
| 71:25 | to the pool with a uh a or a girlfriend and got under the |
|
| 71:30 | , looked at each other with goo eyes and said something stupid like a |
|
| 71:36 | ? If you talked underwater. Have ever talked underwater? You didn't have |
|
| 71:39 | be with the boyfriend or girlfriend? just like to think, you |
|
| 71:41 | it's more likely that you did it recently with someone that you were interested |
|
| 71:45 | . When you're a little kid, like making poop noises and stuff, |
|
| 71:49 | ? So, but have you ever that? Have you tried to talk |
|
| 71:52 | you talk underwater? Can you talk the same loudness or you have to |
|
| 71:55 | more noise, don't you? Because water doesn't move with the same degree |
|
| 71:59 | ease as air does. And so kind of why you have to have |
|
| 72:03 | amplification. So you're not changing the , you're just changing the loudness. |
|
| 72:09 | so what you're doing is you're creating wave in this environment up here. |
|
| 72:15 | ? And that wave has a wave , all right. And that wavelength |
|
| 72:21 | comes in and it's gonna move to certain point along the scale of |
|
| 72:27 | That's what this is trying to show . So if I make high pitch |
|
| 72:31 | , right, that high pitch noise gonna basically find some point. That's |
|
| 72:36 | the front end. If I'm doing low pitch noise, it's gonna be |
|
| 72:40 | place at the back end. Think a keyboard like on a well on |
|
| 72:45 | piano one end you got the and other one is the same sort of |
|
| 72:52 | . So the frequency determines where that is coming and this is just trying |
|
| 72:58 | show that right. So here you high frequency, here's low frequency and |
|
| 73:03 | , we've unwound the cochlea so that can visualize it. All right, |
|
| 73:08 | that wavelength can be like this or can be like this right now where |
|
| 73:16 | frequency uh hits. In other it's not gonna go um It's not |
|
| 73:22 | go ti ti ti ti ti ti ti ti ti. Oh This is |
|
| 73:25 | I stop. It's literally, I so big that this is where I'm |
|
| 73:29 | cause displacement of the vestibular membrane. I'm just gonna go back a |
|
| 73:35 | All right. Number a point. let it work, right. So |
|
| 73:41 | I have a very short frequency, gonna basically cause displacement of the vestibular |
|
| 73:46 | here. If I have a low , it's way gonna be here. |
|
| 73:49 | I'm some place in the mid, displacing the membrane some place in the |
|
| 73:53 | region. All right. And that's cause the membrane wherever that displacement is |
|
| 74:00 | go down, it's gonna cause the to move. Right. So I |
|
| 74:05 | fluid. Here's my vestibular membrane, vestibular membrane moves, I have a |
|
| 74:10 | bunch of fluid in here that if move this membrane, what's gonna happen |
|
| 74:13 | the fluid right here? If I this, what's going to happen to |
|
| 74:18 | fluid? If you squeeze a tube toothpaste, what happens is the toothpaste |
|
| 74:23 | the middle where you're squeezing it moves . So I'm getting movement of this |
|
| 74:29 | . Now this membrane, the Basler also moves and so I can get |
|
| 74:33 | Basler membrane to move. So wherever see displacement, that membrane, both |
|
| 74:37 | vestibular and the Basler membrane are going move. All right. Now when |
|
| 74:42 | happens. So here's the Basler Remember the tectal membrane is very, |
|
| 74:48 | stiff. I always pick on I I'll pick on you today. |
|
| 74:52 | right. Put your arm straight out just right. So she's a text |
|
| 74:56 | memory. Look how stiff her memory , it stays right there because it's |
|
| 75:05 | stiff. See, look at See, it stays right there. |
|
| 75:08 | I have a uh the basal the vestibular membrane and I'm moving like |
|
| 75:14 | , and it's staying stiff and on basal membrane, I have hair |
|
| 75:17 | What they're doing now is as they , they're gonna detect the movement of |
|
| 75:22 | fluid underneath there. Right? Uh I, I don't have three |
|
| 75:27 | . If I had three arms, do that. All right. And |
|
| 75:31 | what happens is, is that as go up and down, the fluid |
|
| 75:35 | around those hair cells and the hair are being bent back and forth. |
|
| 75:40 | , really, the only one that's interested in is the inner hair |
|
| 75:44 | So as the inner hair cell is moved back and forth, it's actually |
|
| 75:50 | and closing channels on the hair cells it to depolarize. And because the |
|
| 75:57 | represents where high notes and low notes depending upon where I'm stimulating that hair |
|
| 76:04 | , that hair cell only detects that , right. So if it's a |
|
| 76:12 | wave that has a frequency of 1600 hair cell at 1600 detects that all |
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| 76:17 | other ones don't move the sound wave through, right? So it goes |
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| 76:23 | causes the basal membrane to move and it continues on, I'm going backwards |
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| 76:29 | . So it basically comes in, through and then that sound wave moves |
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| 76:32 | this way in the round window. it bulges and absorbs the energy so |
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| 76:37 | it doesn't keep going back and forth how we talked about how light goes |
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| 76:41 | and doesn't come out, right? that would be bad for vision, |
|
| 76:47 | energy goes in and gets lost. gets dissipates there. So as I'm |
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| 76:54 | back and forth, I'm detecting the of that membrane and the movement of |
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| 76:59 | , of the fluid through that hair . So this is what the hair |
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| 77:04 | is doing, right? It opens closes. So if I move towards |
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| 77:09 | cannoli, I'm gonna depolarize. If move away, it's gonna close. |
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| 77:13 | basically what I do is I produce potentials, then I stop, ax |
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| 77:17 | stop. And it's those action potentials then move down those uh down through |
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| 77:23 | spiral ganglia and out through the vestibular sorry, the cochlear nerve to the |
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| 77:30 | to say, guess what you just this frequency. Now that's really, |
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| 77:37 | slow motion. Listen to my I make a lot of interesting |
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| 77:41 | don't I, I mean, you understand my words, but in |
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| 77:46 | I'm just making a bunch of ah , right? But your brain takes |
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| 77:52 | and it's working up and down that . Sometimes things are being activated at |
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| 77:56 | same time, some things are some things are softer and all that |
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| 78:00 | is being processed at the level of cochlea and then it's sent onward into |
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| 78:06 | auditory pathway. So frequency depends on I'm actually stimulating amplitude. How |
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| 78:17 | how much movement do I have is a little bit of movement or is |
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| 78:21 | a lot of movement, the more I have more acu potentials I |
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| 78:31 | So this is what the sound It goes through that oval window through |
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| 78:37 | vestibular membrane causes a movement in the duct detected by the inner hair |
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| 78:44 | The sound wave continues through the Basler and then dissipates at the round window |
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| 78:50 | the hair cell, I produce an potential that action potential. So there's |
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| 78:55 | basal membrane, that action potential goes through the vestibular cochlear nerve goes to |
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| 79:01 | cochlear nuclei. That kind of makes , doesn't it cochlear nerve to the |
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| 79:06 | nuclei right up to the superior Here's that other crazy word, the |
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| 79:15 | colliculus telling us where sound is coming and then on to the medial geniculate |
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| 79:24 | . I mean, I actually had learn these for a reason. |
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| 79:26 | And then on to the primary auditory so that I can distinguish what the |
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| 79:30 | actually is. So I'm not making , words are coming from my |
|
| 79:39 | Now, again, if you look the cortex, it's to of typically |
|
| 79:43 | . So it matches this. So you were to map the keyboard of |
|
| 79:51 | auditory cortex, it'd go from high to low notes. Now, there's |
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| 79:55 | lot more complexity in there. Uh not gonna get to, but that |
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| 80:00 | of just gives you the big picture back to the outer ear, why |
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| 80:06 | ear is so shaped. I want to take a look at the person's |
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| 80:08 | next to you. Just, just take a look. How |
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| 80:12 | Isn't that weird looking funny looking Since you're too shy, I'll, |
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| 80:17 | show you my ear and see how look like. It's not like a |
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| 80:23 | dish. It doesn't point things, that shape helps us to map the |
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| 80:29 | of where the sound comes from. is trying to show you like here |
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| 80:32 | have sound and it's showing you how is being bounced off those little |
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| 80:37 | weird little rims that we have, know, and what it's doing is |
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| 80:41 | directing the sound through that acoustic and upon where the sound comes from and |
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| 80:49 | it's reflected, it will hit the geniculate nucleus at different times. And |
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| 80:55 | that timing difference that our brain uses determine direction of sound. So vertical |
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| 81:06 | , basically, it's how it's being on that, on the horizontal |
|
| 81:12 | High frequency sounds wavelengths are really, small. So you create a sound |
|
| 81:18 | . If you've ever seen, if can go, you can go and |
|
| 81:20 | up a wave shadow. If you like an island and a bunch of |
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| 81:23 | hitting the island, you'll see that waves kind of go around and create |
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| 81:27 | like Eddie behind it. But that's of what's happening here is there's like |
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| 81:31 | Eddie of sound waves behind and so hitting the right ear, not really |
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| 81:38 | the left ear. So your brain , oh, that's coming from the |
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| 81:41 | hand side. All right. But they are low frequency, sounds the |
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| 81:46 | in which it hits this one and hits that one are different. And |
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| 81:49 | it uses that timing to as, a, as a way to detect |
|
| 81:56 | . All right. So it's the does that kinda makes sense here? |
|
| 82:02 | about the the pathway? It's a bit hard but I mean, just |
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| 82:07 | of walk it out, go through membrane. What are the bones? |
|
| 82:10 | is the oval window? What is doing in the vestibular duct? Why |
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| 82:15 | it passing through the vestibular membrane? does it pass? Why does it |
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| 82:19 | at this particular point? That's all the frequency, right? What does |
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| 82:24 | do when it gets into the cochlear ? Why do the hair cells |
|
| 82:27 | What's the purpose of the tectal Ask those questions while you're studying? |
|
| 82:32 | it will make this process clear for . Don't just sit there and look |
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| 82:36 | the picture and go OK. I got it. All right. |
|
| 82:43 | that? I'd say. Have you been to Astro World? But it |
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| 82:47 | longer exists. Uh They have this at and I, I know they |
|
| 82:51 | it at the aquarium downtown. And you go to six flag, what's |
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| 82:54 | one in San Antonio? The six in San Antonio Fiesta, Texas. |
|
| 82:59 | you. Seen that. Fiesta Anyone like to ride that bad |
|
| 83:06 | Yeah, I fell off a I fell off a cliff broke and |
|
| 83:10 | got a big old hole in my . Talked about this. I know |
|
| 83:13 | that's like, you know, at very bottom it doesn't break and everyone |
|
| 83:15 | . Oh, that was fun. you hit and splat and it hurts |
|
| 83:18 | lot. So I, I did my favorite but this is what would |
|
| 83:22 | a vertical movement you wanna drive like . This is how I think I |
|
| 83:28 | . Not like a woman. I I look cool when I drive |
|
| 83:34 | My natural speed is around 80 miles hour. You know, don't get |
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| 83:39 | my way. You just don't be . That's, that's my motto. |
|
| 83:42 | be traffic. All right, that be horizontal movement. And then this |
|
| 83:46 | what I was describing. If you understand what I was saying the other |
|
| 83:49 | about the, the human gyroscope. it is 123 rings. You get |
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| 83:53 | strapped into that spin, one spin the next ring, spend the |
|
| 83:56 | ring and they all go on different . So your movement is all in |
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| 84:00 | directions, have a couple of shots tequila before that and you will be |
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| 84:05 | life. You will understand the hardness , of parting hard. All |
|
| 84:13 | what we, why I'm showing you 33 things is because these three things |
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| 84:19 | like or are similar to the three of movement that our brain detects vertical |
|
| 84:23 | , horizontal movement, angular movement. . So we have different structures that |
|
| 84:28 | responsible for that for the vestibule has two organs, the utricle and |
|
| 84:32 | These are also known as the otolith because they have odors and you're |
|
| 84:37 | I don't know, otolith is, worry, we'll get there. All |
|
| 84:40 | . But they're distinct because the semicircle do not have otoliths. All |
|
| 84:44 | So these look at the linear movement your head. OK. That's really |
|
| 84:50 | . It's all about. What's your doing, right? So, linear |
|
| 84:54 | would be vertical and horizontal, semi canals. You have three of them |
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| 84:59 | they're in three planes. So they're the X, the Y and the |
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| 85:01 | plane. And what they do is look at angular acceleration along those three |
|
| 85:08 | . All right. So that's the way to think of these, these |
|
| 85:13 | . So we'll start with the semi canal. So remember what we said |
|
| 85:17 | that there is a duct in the semi circular duct, you can |
|
| 85:21 | that here, there's these bulges. here you can see the 3123, |
|
| 85:26 | have these wide regions that are called . So here's the Aula inside the |
|
| 85:32 | . You have this speed bump It's called the cupula. I'm gonna |
|
| 85:37 | go ahead right now and just warn three of the words we're gonna use |
|
| 85:40 | with LA. We got an Ampulla . We're gonna talk about a macula |
|
| 85:44 | a second. So slow yourselves down you read these things. All |
|
| 85:49 | an Aula is the broadening spray space . It is the Ulla. It's |
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| 85:55 | speed bump. All right. And have fluid that sits inside that |
|
| 86:01 | Now, you have a all three . When you move your head, |
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| 86:06 | inertia of that fluid is first static then it begins to move after you |
|
| 86:11 | . So when you go, what's ? The fluid in there is sitting |
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| 86:16 | and then your head moves and then fluid moves after you've moved your head |
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| 86:20 | when that fluid moves, it causes cupula to move, right. |
|
| 86:25 | it's pressing on the cupula to cause to bend inside the cupula. That's |
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| 86:31 | you're gonna see hair cells, which the mechanical receptors. They have the |
|
| 86:36 | and so when they bend, they're detect the movement of the cupula or |
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| 86:40 | , that's what they're doing. So when we were hearing, we were |
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| 86:44 | not the sound waves, we were the movement of fluid that was moving |
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| 86:49 | the same frequency as the sound So it's not a detect direct |
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| 86:55 | same thing here. I'm not detecting movement of the body. I'm detecting |
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| 86:58 | movement of the fluid, right. so when I turn my head, |
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| 87:04 | of my semicircular canals are are facing so So here's the canal in the |
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| 87:11 | plane. So this would be where ample is located. So I have |
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| 87:15 | facing inward, the other one facing other way, right? So when |
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| 87:19 | turn the K Kcia are being bent opposite directions, so that those signals |
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| 87:26 | both sides of the brain tell my oh, the hair over on this |
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| 87:30 | is basically causing rapid action potentials. on this side is is not. |
|
| 87:35 | you're turning your head to the left if I turn my head the other |
|
| 87:40 | , the Kia flipped the direction and tells your brain, oh, you're |
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| 87:44 | your head to the right because of direction of the bending of the hair |
|
| 87:47 | . Now, this sort of angular occurs like even when you're looking up |
|
| 87:51 | looking down, right? Or if being spun in a circle, if |
|
| 87:56 | ever laid down on a merry go . Did you ever do that? |
|
| 87:59 | your kids let you, did your let you go play on playgrounds? |
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| 88:03 | , they did. Were you allowed go on the merry go round? |
|
| 88:07 | anyone shaking their head. Yes. . Lie down on the merry go |
|
| 88:13 | . Spin really, really fast. get up and it's like that was |
|
| 88:19 | , right? But that's the three planes, the X, the Y |
|
| 88:24 | then the Z. Yeah. So what the semi circum canals do. |
|
| 88:32 | as a couple of ways the hairs when the hairs move. That's just |
|
| 88:36 | you the degree of movement in that plane. Pretty simple. The otolith |
|
| 88:43 | we said are responsible for vertical and movement. All right, I'm gonna |
|
| 88:48 | out for a second. You guys doing vectors way back when. All |
|
| 88:54 | . So vectors have two components. you don't remember them, think about |
|
| 88:59 | me. Vectors have component number one magnitude. The second one is |
|
| 89:10 | See that's why you go back to me because the villain vector, I |
|
| 89:14 | crime that has magnitude and direction. All right. So what is magnitude |
|
| 89:25 | direction where I'm going? If I'm in the vertical plane? Do I |
|
| 89:30 | magnitude or do I do I have ? Yes. Up and down. |
|
| 89:35 | I have uh do I have horizontal in the vertical plane? Do you |
|
| 89:42 | how vectors are actually shown? They an X and A Y component? |
|
| 89:48 | you do have a horizontal component. is the horizontal component in the vertical |
|
| 89:54 | ? Zero? Right. I'm telling this because we're gonna keep it basic |
|
| 90:01 | . Vertical, horizontal is horizontal. when you move at an angle, |
|
| 90:06 | have both a vertical and a horizontal so both are being stimulated to a |
|
| 90:12 | degree. OK. So with that mind, first, let's go and |
|
| 90:16 | do the basics. All right. I tried to highlight things to make |
|
| 90:20 | easy so that you can see the to help you remember what goes |
|
| 90:23 | What? All right. So the organ which is found in the |
|
| 90:28 | there's two of them. We have mac or sorry, we have the |
|
| 90:30 | utricle saccule. What they have is are basically this goo like structure |
|
| 90:35 | You can see the goo like structure underneath them hair cells just like you |
|
| 90:39 | in the saccule, right? So hairs are embedded in that macula, |
|
| 90:46 | also embedded in the macula are a of crystals. These are the |
|
| 90:50 | The otolith is calcium carbonate. And that calcium carbonate crystal does is it |
|
| 90:55 | mass to the macula. So if were to take your macula and put |
|
| 90:59 | on its side, it would want droop because it has mass to |
|
| 91:04 | that kind of makes sense, It's like putting fruit in jello, |
|
| 91:09 | will move. But if you put in it, it moves more vigorously |
|
| 91:13 | it has greater mass. Right each of the hair cells are associated |
|
| 91:20 | a nerve fiber, they come they form the vestibular nerve. So |
|
| 91:25 | nerve joins up the cochlear nerve. where you get the vestibular cochlear |
|
| 91:28 | OK. So that's the easy So when I move the inertia is |
|
| 91:35 | to be felt by that greater mass cause that movement of the macula, |
|
| 91:40 | is going to be detected by the cells. So what do we |
|
| 91:44 | We have the utricle the utricle has hair cells in the vertical position. |
|
| 91:51 | . So vertical position. So when utricle moves, what I'm doing is |
|
| 91:57 | bending the hair cells back and So I'm detecting horizontal movement. |
|
| 92:04 | I'm in the car driving fast. I'm looking at the saccule, the |
|
| 92:10 | has the hair cells in the horizontal . So when they bend, I'm |
|
| 92:17 | movement in the vertical plane. This the dungeon drop, the elevator, |
|
| 92:24 | . Ok. So, Saccule detects in the vertical plane. Utricle detects |
|
| 92:29 | in the horizontal plane. When I much younger, my friend had a |
|
| 92:34 | GT back when they actually made muscle with six cylinder plus eight cylinder plus |
|
| 92:39 | cylinder engines. And he wanted to if his car really went 0 to |
|
| 92:45 | in what they told us. Have ever tried that? See how fast |
|
| 92:49 | car can actually get going. This awesome. We're on a straight |
|
| 92:54 | He's looking at his watch like I'm gonna tell him whether or not |
|
| 92:57 | going off the road. We did to 16. I think it was |
|
| 93:01 | five seconds. It was awesome. one of the, those each corsa |
|
| 93:09 | the movement? Which one made me like I was being pushed into my |
|
| 93:14 | utricle. There you go. All . Now, when your head is |
|
| 93:20 | erect, you're not gonna to detect sort of changes when you, when |
|
| 93:24 | move, just like we described that , you're gonna detect it. Utricle |
|
| 93:29 | saccular. Those are really easy. that's not the only time you're gonna |
|
| 93:32 | them. This is where we're coming . And I said, look when |
|
| 93:35 | look up, yeah, the semi canals were looking at angular movement. |
|
| 93:39 | my utricle and saccular are both involved that because they also detect that |
|
| 93:46 | When I tilt my head, the , those um, those otolith organs |
|
| 93:52 | being pulled towards the earth, so play a role as well. All |
|
| 93:58 | . So when you nod your head and forth, we're gonna say on |
|
| 94:02 | test, it's the semi circular But in reality, what is |
|
| 94:08 | Semi circulars, utricle and sacu. . All of the things play a |
|
| 94:15 | in detecting the movement of the It's just which ones play which role |
|
| 94:20 | your movement is all three at the time. But we just keep it |
|
| 94:26 | head in the horizontal plane. That's driving fast head in the vertical |
|
| 94:33 | That's the dungeon drop. That's the . OK. You're gonna remember that |
|
| 94:41 | the exam. Simple on the OK. Wow. I got to |
|
| 94:48 | I wanted to go. Are there about equilibrium? Questions about, question |
|
| 94:53 | , question about semi circular canals. one wants to know whether or not |
|
| 94:58 | mackerel tastes good because it's jello cherry . You just wanna go home, |
|
| 95:08 | you? No questions? Really? right. Let's talk about the motor |
|
| 95:17 | . What is the motor pathway? do you get a sense when you |
|
| 95:21 | a motor pathway? What do you we're trying to do? Move? |
|
| 95:25 | who's talking to? Who are my ? Talking to my brain or my |
|
| 95:28 | ? Talking to my muscles? Say loud. Say proud brains talking |
|
| 95:34 | don't be afraid, brains talking to muscles. So we're looking at pathways |
|
| 95:39 | are moving downward, right? The time we talked, we talked about |
|
| 95:43 | dorsal and the lateral anterior in, were talking about somatic century pathways, |
|
| 95:48 | way is where somatic century going down . I'm taking information into my |
|
| 95:54 | Now I'm taking information and telling my what to do. That's what the |
|
| 95:58 | pathways are. These are polysynaptic So there's many different parts of the |
|
| 96:03 | that are gonna be involved in a sense. What we're gonna do is |
|
| 96:07 | gonna start at the cerebral cortex or brain stem, but mostly cerebral |
|
| 96:13 | we're gonna travel down the spinal cord we're going to go down to our |
|
| 96:16 | organs. Remember, effector organs simply a fancy word for saying the thing |
|
| 96:21 | does the effect. So we're talking muscles, we're if we're talking about |
|
| 96:24 | , but motor also refers to the . You know, when you start |
|
| 96:29 | about the salivation, right? And start salivating, that is a motor |
|
| 96:36 | causing the glands to produce saliva. now. Functionally, muscles are the |
|
| 96:44 | that are skeletal muscles in particular is movement. All right. But that's |
|
| 96:50 | what motor pathways are limited to. also autonomic, right? So if |
|
| 96:54 | are involved, we're dealing with you can't make yourself salivate, but |
|
| 96:58 | can start thinking about food which will you to salivate, right? Think |
|
| 97:04 | lemon, lemon drops. You guys like lemon heads. If you think |
|
| 97:08 | lemonheads for a while, does that you go right back here? |
|
| 97:14 | posture. Do you guys think about posture a lot? Thank you for |
|
| 97:17 | up, right? Usually I point out, I will see people sit |
|
| 97:22 | . I have actually even the middle sit ups and I'll watch people do |
|
| 97:25 | . All right. So balance when talk about balance again, we're talking |
|
| 97:27 | equilibrium, muscle tone. Do you to think about your muscle tone? |
|
| 97:32 | , I mean every now and then may go like OK, let's sit |
|
| 97:35 | straight and put my shoulders back, out, flatten my stomach, but |
|
| 97:40 | not your normal posture, right? these are things that are done in |
|
| 97:46 | unconscious way. So it, with to these, we're saying we're starting |
|
| 97:51 | cerebral cortex or the brain stem, gonna see input from the basal |
|
| 97:57 | we're gonna see input from the All right. So what we're talking |
|
| 98:01 | here is we're now saying here's the of movement. How does movement |
|
| 98:07 | And we're going to start throwing in these different things that we've already talked |
|
| 98:11 | . When it came to movement, talked about the different part and said |
|
| 98:13 | is involved in movement. This, is involved in movement. This is |
|
| 98:16 | in movement, plus other stuff. we're going, here's movement. What |
|
| 98:19 | the things that we threw in that ? These always have two neuron |
|
| 98:25 | All right. So the first neuron always called the upper motor neuron. |
|
| 98:29 | second one is always the lower, motor neuron, right? The two |
|
| 98:34 | . So remember how we had, had the dorsal columns and we have |
|
| 98:36 | interior lateral system. This is kind what this is, is the direct |
|
| 98:40 | the indirect. So there's two different of pathways. What do you think |
|
| 98:44 | means? Go straight there? What you think indirect means? It's probably |
|
| 98:49 | what the direct is. It's slightly different. All right, we're |
|
| 98:55 | talk about lower motor neurons first because the easiest one. All right, |
|
| 98:59 | already spent some time. So here our, our cell body or |
|
| 99:03 | not our cell body, our spinal . And what we're interested in is |
|
| 99:06 | is the cell body located? Well, if we're dealing with the |
|
| 99:10 | somatic system, our cell body is where ventral horn, right? If |
|
| 99:19 | are autonomic, where are we going be located? Lateral horn? |
|
| 99:25 | So that's one of the key things we need to remember here. The |
|
| 99:29 | stays the same. We've already learned organization. So the cell body is |
|
| 99:32 | there, then we travel out via ventral route. We join up to |
|
| 99:36 | spinal nerve and then we travel to to the direction that we need to |
|
| 99:40 | . Now, here's the thing about lower motor neuron. This makes this |
|
| 99:44 | much easier, lower motor neurons are , always, always no exception to |
|
| 99:48 | rule, the absolute truth, If you want a muscle to |
|
| 99:54 | you need to tell it to you want a muscle to stop |
|
| 99:57 | stop sending the signal and it will . Ok. So we have a |
|
| 100:03 | that is always excitatory in the lower upper. What do you think if |
|
| 100:09 | is always? And I haven't talked , what do you think the upper |
|
| 100:13 | one or the other? Right? . Typically we have two different types |
|
| 100:18 | fibers. So here is a We have an alpha motor neuron will |
|
| 100:24 | to a region on the outside that the muscle to contract and tells how |
|
| 100:29 | it should contract, send the This is how much contraction you want |
|
| 100:33 | make. We also have a gamma neuron. The gamma motor neuron goes |
|
| 100:37 | into this little tiny structure called the spindle. And it innervates muscle that's |
|
| 100:43 | inside this little tiny structure. It contracts but it is associated with sensory |
|
| 100:50 | that are looking at the degree of . If these two things don't |
|
| 100:54 | then you're out of where you're, not in sync, then your, |
|
| 100:58 | muscle isn't contracting to where it needs go. Right? So when I'm |
|
| 101:03 | to hold something out to the if my arm starts slipping, my |
|
| 101:07 | says, oh, I can detect greater degree of stretch in here. |
|
| 101:12 | want it to this muscle. I , I want this to match |
|
| 101:16 | So what I'm gonna do is I'm to constrict this more so that the |
|
| 101:21 | thing contracts. And so that's how position my arms, my legs and |
|
| 101:27 | else, all my muscles because I'm to match the gamma and the alpha |
|
| 101:33 | . All right. So detection is in here. It doesn't do a |
|
| 101:36 | of work, it's still contracting, it's not actually doing the, the |
|
| 101:41 | work, the alpha is doing the work. So this is used to |
|
| 101:45 | the degree of stretch and whether or you're doing what the muscle is trying |
|
| 101:50 | accomplish. These muscles also dete are these fibers that uh demonstrated these pathways |
|
| 102:01 | somatotrope. All right. So, , as we said is basically just |
|
| 102:05 | arrangement. So as you move from to upper, it's gonna be |
|
| 102:12 | um you're more lateral, the further higher you are, you're more |
|
| 102:16 | the lower you are in the So basically, as you go |
|
| 102:20 | you're gonna find yourself going in into same position and remember this is going |
|
| 102:25 | be reflected again in M one in motor homunculus. So those fibers are |
|
| 102:32 | in a specific location that maps to specific point in the body. We |
|
| 102:38 | about motor units previously. And so does that motor unit remember? It |
|
| 102:43 | represents that alpha fiber and where it's and all the neurons that are um |
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| 102:50 | sorry, all the muscle cells that neuron is going to. So in |
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| 102:55 | particular case, we have 12, of them, I guess they did |
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| 102:59 | terrible picture here. But all of cells are being innervated by this one |
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| 103:03 | neuron. So this is a motor and produces that degree of force. |
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| 103:11 | talked about delicate activity versus course Previously, we have these motor units |
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| 103:18 | equally spread out through the muscle to sure that we're pulling all throughout the |
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| 103:25 | . So it can do the movement you're trying to accomplish here. |
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| 103:30 | we see the cortex and how the has those six layers. All |
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| 103:34 | they're found uh the the cell bodies primarily found in layer five. |
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| 103:39 | I'm not gonna ask you that but there's a group of cells that |
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| 103:43 | playing a role in regulating uh those motor neurons or not regular, but |
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| 103:49 | become those upper motor neurons. So lower motor neurons originate in the spinal |
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| 103:54 | , the upper motor neurons originate here the cortex and they are traveling |
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| 104:00 | they will cross over. In other , they'll deco at some point. |
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| 104:05 | if I'm trying to control my right , which, which side of my |
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| 104:10 | am I using my left? So originating up here in the motor |
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| 104:17 | those bet cells layer five, not so important, but they come |
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| 104:21 | they cross over at the pyramids most and they travel down to the spinal |
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| 104:27 | . In this case, it would right down to here. And then |
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| 104:30 | here are the lower motor neurons traveling down to make my fingers wiggle. |
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| 104:35 | kind of makes sense. So we the cortex, this is where the |
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| 104:45 | originates. Probably the meah we're going see decussation. That's the crossover. |
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| 105:03 | right, we get down to the cord and where are we going to |
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| 105:10 | if it's a muscle, where is gonna be horn? And now what |
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| 105:19 | gonna see is the lower motor neuron then that goes on to whatever muscle |
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| 105:33 | kind of makes sense. Now, you visualize that? So these are |
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| 105:42 | directly uh innervate the lower mouse motor and or there might be an interneuron |
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| 105:48 | place so that the signal can be . All right. And then here |
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| 105:54 | uppers can be excitatory or I should this or inhibitory. All right. |
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| 106:05 | , let's think about this if I lifting up my leg like. So |
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| 106:12 | have a muscle that causes the contraction I have a muscle that's relaxing, |
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| 106:18 | ? What's the muscle that's causing the ? What do we call that |
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| 106:25 | And the muscle that is relaxing Ok. See stuff you already |
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| 106:30 | I'm not, I'm not like this stuff you've already learned. Ok. |
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| 106:36 | if the upper motor neuron is telling muscle, that agonist to contract, |
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| 106:41 | do you think it's telling the antagonist relax? Right. So that upper |
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| 106:48 | neuron is creating an excitatory signal and also creating an inhibitory signal, it's |
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| 106:56 | to two different places, right? the the lower motor neuron to the |
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| 107:02 | is always excitatory. The lower motor to the antagonist is always excitatory as |
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| 107:08 | . I'm just telling one to contract I'm telling the other one not |
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| 107:12 | which is why they're moving opposite each . That kind of makes sense. |
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| 107:18 | right, we'll see how far we in this part because it all goes |
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| 107:28 | . All right. So here's the cortex. We've seen this before. |
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| 107:33 | typically organized located in the precentral This is where the upper motor neurons |
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| 107:41 | beginning. So we've seen it in , all right. And one is |
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| 107:49 | with another region called the premotor All right. So up here in |
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| 107:55 | cartoon, here's the premotor cortex, the motor cortex, they're right next |
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| 108:02 | each other. It has some upper neurons. But what it's primarily doing |
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| 108:08 | it's working with the primary motor cortex store motor memory, it tells you |
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| 108:15 | to make a movement relative to what want to do. The example I'm |
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| 108:18 | here is the wave versus the high everyone wave at me. Oh, |
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| 108:22 | . And you know how to give a high five. It's a different |
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| 108:28 | , say muscles, right? So in context also it produces movements in |
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| 108:37 | to sound movements, in response to cues. All right. Now, |
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| 108:42 | does that mean? Does it mean turning my head? No. All |
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| 108:45 | . Everybody, you know those types things. You know, if someone |
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| 108:51 | at you, what do you You wave back the visual cue. |
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| 108:55 | that's the idea. Now, it send signals directly uh down the spinal |
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| 109:01 | if necessary because it has upper motor , right? But it's primarily talking |
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| 109:07 | and forth here. We have two cortex that you should be aware |
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| 109:13 | We have the prefrontal association cortex. also have the poster parietal association |
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| 109:20 | they're helping to modify your movements. . So they're talking to the primary |
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| 109:27 | , they're providing information. All Now, what the prefrontal cortex is |
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| 109:33 | is ensuring that your muscle movement is , right? So it is processing |
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| 109:40 | upon the information that it's receiving OK. So when someone waves at |
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| 109:45 | across the parking lot, what do do? I'm supposed to wave back |
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| 109:50 | smile like I know them. Even I don't, I'm gonna pretend I |
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| 109:55 | who you are. All right. it's basically the proper, that's much |
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| 109:58 | than flipping them off. That would , be like the inappropriate behavior. |
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| 110:02 | right. So, notice what it's . It's talking to the premotor or |
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| 110:08 | motor cortex as well as the premotor here with the bridal. Associate. |
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| 110:13 | you're doing is you're dealing now with . OK. I'm touching things. |
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| 110:17 | am I supposed to do when I things? Like when you reach into |
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| 110:21 | , into your drawer to pick up and something slimy graduate. No, |
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| 110:27 | , no, no, no. that's, that's not supposed to be |
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| 110:30 | , right? So it also provides muscle movements based on that. And |
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| 110:38 | takes that sensory information that you're, experiencing and helping you to determine how |
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| 110:43 | do that movement. So the motor and the premotor cortex, that's when |
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| 110:55 | talk about the direct pathways, that's we're using. Ok? I think |
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| 111:01 | just gonna stop here. Yeah. we come back, we're going to |
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| 111:05 | about where the indirect start and then going to kind of put all the |
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| 111:10 | together and then what we're going to is finish up movement and then we're |
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| 111:14 | to deal with autonomic, which is straightforward and fun. So you got |
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| 111:18 | long weekend. Well, not a weekend, you have a two day |
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| 111:22 | , come back, then we have Day, celebrate, have fun, |
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| 111:27 | , don't blow off any fingers blow up your little part of America |
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| 111:32 | not your fingers. And then one off and then the test, or |
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| 111:38 | it two days off in the I can't remember. Ok. So |
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| 111:41 | day off and then the test. right, final grades will be like |
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| 111:44 | , on Friday next week. But see you guys on Monday. All |
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| 111:47 | . Enjoy yourselves. Woohoo. Almost , almost done. Probably shouldn't be |
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| 111:55 | that out |
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