| 00:00 | it's not. So this is going be lectured 16 of neuroscience and you |
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| 00:08 | watch lecture 15 Visual system, the if you haven't done so already the |
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| 00:16 | age video point. And when you this uh lecture, I'm just gonna |
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| 00:29 | you over some of the key I wanted to do it on the |
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| 00:34 | but it's a little bit slow. starting the first component of the visual |
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| 00:41 | is understanding the I. And understanding the anatomy. Yeah. Of the |
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| 00:50 | and also the properties of the So the light has certain properties when |
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| 00:54 | strikes the eyeball, there's certain anatomy the eyeball and there's certain of course |
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| 01:01 | of the visual system. Why is called the visual system? Because it |
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| 01:05 | multiple compartments circuits. If you made structures in the brain that processes visual |
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| 01:13 | and the stream of the visual information from the eye into the thalamus of |
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| 01:18 | funicular nucleus and to the primary visual and subsequently split into two streams. |
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| 01:24 | I talked about that in the election dorsal parietal stream and ventral inferior temporal |
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| 01:29 | . And you can see that the away it goes from the primary visual |
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| 01:33 | area, if you want, the hierarchically advanced and complex the processing is |
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| 01:39 | the more it gets co joined with sensory modalities such as hearing uh emotional |
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| 01:45 | of what is going on and such sensory information as we discuss all of |
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| 01:50 | sensory information goes through thalamus and the columnist. You have the nucleus. |
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| 01:55 | nucleus nucleus had a quick discussion about olfactory system which actually does not have |
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| 02:02 | important column as it goes bypasses thomas as I said it has an input |
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| 02:07 | thomas to join it with other information . So it does have if not |
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| 02:14 | direct processing of smell for for the input in processing that smell. So |
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| 02:20 | just reminded me that this is sort a little bit of an exception in |
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| 02:24 | sensory world when you ask that question in general this is the information from |
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| 02:31 | will go into thalamus and we'll go the primary auditory cortex And so we |
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| 02:37 | all of these different components of the that I walked you through and you |
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| 02:41 | know them very well. And then talked about the circuit in director we |
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| 02:46 | about the photoreceptors, bipolar cells of ganglion cells. We talked about the |
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| 02:54 | here and the two types of photoreceptors cones and rods that are connected to |
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| 02:58 | south and connected to retinal ganglion cells form the fiber bundle up the optic |
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| 03:04 | which is your cranial nerve to that out and this is actually the bundle |
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| 03:09 | that cranial nerve to it then goes the chasm and part of this bundle |
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| 03:15 | over So there is this light processing to strike the very back of the |
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| 03:20 | moment to excite. Excite the photo with a photo transaction takes place today |
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| 03:26 | understand what the photo transaction is and the circuit actually works when the light |
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| 03:32 | going to be able to make some these retinal ganglion cells fire action potentials |
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| 03:38 | artists will hyper polarize those. So general the only output of the retina |
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| 03:45 | you know is from the retinal ganglion . We talked about the farsightedness and |
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| 03:51 | in that lecture we talked about also layer of circuit control by horizontal and |
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| 04:00 | immigrant cells and we'll look into a bit more detail today. Again, |
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| 04:04 | recall that you have two different types the cone and rod photoreceptors and the |
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| 04:10 | between them, anatomical differences as well the functional differences where the rods are |
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| 04:15 | the night vision and slowly adapting comes for the high acuity vision and require |
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| 04:20 | lot of life. And the arrangement the receptors is such that the |
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| 04:27 | actors are expressed at high densities in area that is very central, right |
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| 04:32 | the pupil in the back of the called a phobia which essentially focuses all |
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| 04:37 | the direct actual rays of light to onto the conflict of receptors. And |
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| 04:40 | robert receptors are responsible for the dark . I located more on the periphery |
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| 04:46 | the retina. And so and phobia have a specialized kind of a cone |
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| 04:49 | structure that uh points all the light to the counts and three types of |
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| 04:56 | depending on the stimulus, the light coming in. This electromagnetic source light |
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| 05:02 | in photons of lives that are coming depending on which wavelength they are. |
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| 05:08 | gonna anxiety the blue green or red and they can excite them in different |
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| 05:13 | . And this is where you get color mixing. And this is where |
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| 05:15 | get the creation of multiple hues. don't see the world in the |
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| 05:20 | red, green, blue colors, printers RgB. We'll see these guys |
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| 05:26 | G B C M Y K. K C M Y K. Seven |
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| 05:29 | . Yes, I am magenta Ok, you got me. So |
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| 05:38 | , but this is how you get uses. So we see quite a |
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| 05:41 | colors by having the ability to excite uh photo receptors at different wavelengths to |
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| 05:48 | degrees. And I always say that are animals that are a lot more |
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| 05:52 | in this world. You can see lot more colors. I'm not saying |
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| 05:54 | they have better vision but they'll see lot more colors. So you can |
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| 05:58 | scattered rays of light and things like . It's really cool. So now |
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| 06:04 | have the anatomy of the eye and next section and is to understand what |
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| 06:11 | going to be doing today is we're to understand the system from several |
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| 06:15 | First of all there is a structure structure of the cells in the |
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| 06:20 | Then each one of these cells have certain function. The photo receptors. |
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| 06:25 | transformed that photo of life into an reaction. A graded synaptic potential graded |
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| 06:32 | potential that gets communicated to bipolar And then retinal ganglion cells are the |
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| 06:38 | ones to produce this all our non which is different from the grated perceptive |
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| 06:44 | response which is an action potential and that information to lateral funicular nucleus. |
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| 06:50 | there's a structure there is a there's functionality in that circuit. And |
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| 06:56 | the time we're done on thursday you'll how all of this creates a primitive |
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| 07:00 | primal image of the outside world at level of the primary visual cortex. |
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| 07:06 | we've learned in the past with medical signaling is that you have to have |
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| 07:09 | neurotransmitter in order to activate the And that receptor is linked to G |
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| 07:15 | and a couple of cascade secondary And you can increase the production of |
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| 07:21 | messenger. We also saw opposing actions metabolic tropic chemical signaling. Some increased |
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| 07:28 | messengers of this decrease. We looked the tropic and memorable tropic having opposing |
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| 07:36 | . This is a system and the and the photo receptors where the |
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| 07:40 | Now there's a stimulus, it's not camera and life is linked to the |
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| 07:47 | . Protein. The receptor that contains light sensitive molecule, it's linked to |
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| 07:53 | protein coupled receptor and it causes a in the secondary messenger and actually regulates |
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| 08:00 | flow of sodium. So how does work? Let's first understand what is |
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| 08:06 | and why the system is a little from the other systems. You have |
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| 08:11 | learning so far when we were studying resting membrane potential, we said the |
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| 08:15 | membrane potential in the south, it's -65, 70 million volts. |
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| 08:22 | if you look at the photo receptors the dark, what you call a |
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| 08:27 | potential, maybe the south to actually polarized and their potential is minor study |
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| 08:35 | but the cells don't produce action for . So they're just they're different from |
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| 08:39 | that we were talking about earlier. they're deep polarized because there's a lot |
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| 08:44 | cyclic GMP and the cyclic GMP keeps sodium channel over and the sodium channels |
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| 08:51 | and then -30 middle of balls here the dark the light turns on, |
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| 08:56 | stimulus of light is yellow and the membrane of the photo receptor hyper |
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| 09:04 | So you would say whoa ! The actually had to polarize the cell. |
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| 09:08 | how does that work? And it's about what is downstream in the circuit |
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| 09:13 | . But you will say, well cells in the darker, constantly active |
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| 09:16 | . How come I'm not seeing things I close my eyes. It was |
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| 09:20 | to the circuit, there's a level control and there is inhibition in the |
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| 09:24 | . So this retinal circuit is not all excited for it as a significant |
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| 09:29 | component. So you turn the light and this member and potential goes back |
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| 09:33 | the polarized state in the dark. minus started millones when it is d |
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| 09:40 | and in the presence of sodium it's a lot of glutamate excitatory. When |
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| 09:46 | is not an upper sodium, the GMP gets converted into GMP. There's |
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| 09:53 | particular release, there's no glutamate Uh huh. The light sensitive molecule |
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| 10:00 | now Inside the option this is a configuration. When it hits. Uh |
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| 10:08 | now photo out of life changes into configuration and this confirmation will change activates |
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| 10:17 | G. Protein and G. Pro again in the dark. Its sodium |
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| 10:25 | coming in in the presence of psychology . In the presence of life is |
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| 10:29 | . Protein activation causes the conversion of GMP into GMP by fast for Dia |
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| 10:36 | here and in the absence of cyclic . When there is no cyclic |
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| 10:43 | the sodium channel is closed and the of potential is a hyper power. |
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| 10:54 | , cones require more energy to get more light. Right? The direct |
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| 11:00 | surveys of light rods gets saturated by light and they operate better. They're |
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| 11:06 | sensitive. So a lot of it down to Rod's having those free floating |
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| 11:13 | that actually increase the surface area and them more sensitive to the photons of |
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| 11:19 | . Okay, so we understand that is a circuit here and we are |
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| 11:25 | going to start developing our understanding of is a receptive field. If you |
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| 11:33 | of the uh as a matter of system for example, Which is your |
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| 11:38 | in your body? Where is your field for your right shoulder? In |
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| 11:44 | skin? It's on your right Whereas you receptive field for your left |
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| 11:50 | and your skin of somebody taps is your left shoulder. In other |
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| 11:52 | if somebody taps you on the road , you don't feel it's your left |
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| 11:56 | being tapped. So there's receptive Some of them are large year and |
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| 12:02 | torso on the hand, some of are very small for a time |
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| 12:08 | fine manipulation, fine dextrous movement. but the receptive fields individual system as |
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| 12:17 | . Did you have a question? you like? They are obviously I |
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| 12:28 | checked actually before the before the lecture showing that it's that it's open and |
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| 12:33 | . But but I'll. Okay, how is this organized? And the |
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| 12:51 | ? And what are the receptive fields the retina just talked about the |
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| 12:55 | What are the receptive fields in the ? What is retina seeing? So |
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| 13:00 | turns out that there is collections of receptor cells. Okay, in the |
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| 13:08 | , this photo receptor cells you can here they have zone in the surrounds |
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| 13:19 | . So the center zone can be and the surround can be off or |
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| 13:28 | surround can be armed and the center be off. I hope you're drawing |
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| 13:45 | me. Yeah, I'm joking. Okay. So low system resources, |
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| 14:09 | . Maybe what's going on. So why why is it why is |
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| 14:15 | that you have the receptive fields? other words, do you remember a |
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| 14:18 | ago and said? What happens if have a cooperating into the computer? |
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| 14:21 | does retina see? What does retina with a stalinist process? Well does |
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| 14:27 | process? Where does the picture form the outside world with his emotion, |
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| 14:32 | , everything being joined together? Where this happening? And how is this |
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| 14:37 | ? So what his retina see? if you were to hook up to |
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| 14:40 | computer and this is your retina Retina has collections of photo receptors and |
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| 14:47 | photo receptors react to beams of life are either center beam of life on |
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| 14:54 | surround be mobilized that's on or And this is what retina perceives retina |
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| 15:03 | luminescence difference and that luminescence difference in retinal circuit across retinal circuit is organized |
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| 15:11 | these on off center surround bipolar and ganglion cell receptive field properties. So |
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| 15:22 | way of envisioning is you can isolate retina from a turtle from an animal |
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| 15:28 | can instead of Pokemon electrode in the , whole cell or two you can |
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| 15:34 | it on my electrode array. So can record from 1000 spots in that |
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| 15:41 | . So you can shine the light you can shine the light just like |
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| 15:45 | know you have a flashlight, you adjust the beam, the beam is |
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| 15:49 | broad or the beam is really The beam is really narrow. There's |
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| 15:53 | lot more contrast in one spot, beam is really broad, there is |
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| 15:58 | contrast. So really narrow beams would on photo receptor in the center of |
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| 16:07 | in the surround. And these Micro recordings are really great because then you |
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| 16:13 | actually identify these groups of 30 receptors are responsible to reacting to a small |
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| 16:19 | of light into a larger beam of . And what is the response from |
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| 16:24 | retinal ganglion cells. So as you see these photo receptors, these clumps |
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| 16:28 | the photo receptors or center surround and can measure the receptor field properties by |
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| 16:37 | action potentials of the retinal gang So retinal ganglion cells are the only |
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| 16:43 | that produce the action for controls. this is this timeline here on the |
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| 16:48 | axis is time and each one of black sticks is an action potential. |
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| 16:56 | if you take a light and on center ganglion cells and you'll see what |
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| 17:02 | that? Where's ganglion cells there? not. The ganglion cells are sitting |
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| 17:07 | photo receptors but it's clumps of these receptors. I'm sorry guys, this |
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| 17:11 | the way the retina is built. just the way it is. People |
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| 17:16 | . Why is the center surround. is this? Because that's what it |
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| 17:19 | . This is the structure the function on top of that, the circuit |
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| 17:24 | the chemistry all of it working So the structure is that if you |
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| 17:30 | a beam of light, this focus beam of light on a on photo |
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| 17:37 | that are connected to the on retinal cell, you will get the most |
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| 17:42 | potentials. So if you're shining this of light and yellow here in the |
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| 17:47 | you get the most action potentials. is the beam of light, the |
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| 17:51 | is right here. If you shine beam of light on the surround but |
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| 17:57 | leave the center dark. So you you have a very sophisticated flashlight, |
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| 18:01 | can have only women a justice around not the center. What happens the |
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| 18:07 | from that retinal ganglion cell is So that retinal ganglion cell is an |
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| 18:14 | center ganglion cell, meaning that that cell will be activated. D |
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| 18:19 | producing the most action potentials when the of light is hitting the center. |
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| 18:25 | . The least will be one that of light is hitting this around. |
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| 18:30 | guess what happens if you have even across. There is no change in |
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| 18:36 | frequency of action potential firing because you are not. It's even illumination. |
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| 18:43 | there is no boundaries and there's no in luminescence. All center ganglion cells |
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| 18:50 | just the opposite of center ganglion cells produce the most action potentials when the |
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| 18:56 | regions of the photo receptors are Yeah and it will produce the least |
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| 19:03 | potentials when the center region is activated light. And again it will show |
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| 19:10 | change in the frequency of action potential the illumination is even across the whole |
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| 19:16 | field or even across large patches of regular. Well the whole right you're |
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| 19:25 | white space. There's not much there's not much elimination, there's not |
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| 19:30 | difference. Okay so set the field the receptor area in this case it's |
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| 19:38 | wonder. Sector in this case is that their sector sitting in the retina |
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| 19:44 | one stimulated results in a response of particular sensory neuron. Uh huh. |
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| 19:54 | retinal ganglion cells are going to be that information and through the circuit. |
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| 20:02 | by now you should be thinking, wait a second. There are these |
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| 20:05 | of photoreceptors they get activated by light photo receptors released. Glutamate bipolar cells |
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| 20:18 | is good at it. So how light? There's a circuit, how |
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| 20:25 | light can either inhibit gangly himself excited now. So that's what I just |
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| 20:31 | you before. You have certain on cells, they're excited, more action |
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| 20:37 | or santa, marta or just the . Now it comes down to the |
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| 20:45 | . The circuit is a following. remember there's two most important things to |
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| 20:50 | about this circuit and it's explained in couple of slides. First of all |
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| 20:56 | neuron photo receptor, what the receptors what the photo receptor is doing in |
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| 21:01 | light versus in the dark with respect member and potential and the dark is |
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| 21:06 | polarized in the light is hyper All right, the splitter receptor releases |
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| 21:13 | to me. The other most important to remember is that there is the |
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| 21:22 | from bipolar so that it depends on type of the glutamate receptor. Ethics |
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| 21:29 | that expresses and takin it receptor. plus stands here for signed conserving |
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| 21:39 | son conserving means that if in the this neuron is deep polarized, the |
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| 21:45 | is concerned across the synapse bipolar cell deep polarized is releasing glutamate this off |
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| 21:52 | ganglion cells D polarized. So now look at the situation where you have |
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| 22:00 | . What happens in the presence of in the presence of light. Norah |
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| 22:06 | hyper polarized. That means there is glutamate release. If there's no glutamate |
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| 22:14 | ample kitchenaid and this is hyper This is signed conserving synapse bipolar, |
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| 22:19 | is hyper polarized. That retinal ganglion between bipolar to retinal ganglion cells are |
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| 22:29 | am bikini are signed. Conserving so the light this is hyper polarized this |
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| 22:36 | hyper polarized. And what is this doing is hyper polarized. So is |
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| 22:42 | cell on in the light or it's ? It's off center ganglion cells meaning |
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| 22:50 | in the presence of life this cell actually hyper polarized. Okay, well |
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| 22:56 | interesting. So how do you get sell to dip polarize now and you |
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| 23:01 | over to this side of the second to the left and you look at |
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| 23:06 | negative sign. This negative sign means sign inverting synapse And the sign inverting |
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| 23:13 | instead of containing ample Kinney. For they contain metadata, tropic blue |
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| 23:18 | Chapter six. Remember how we talked how I wanna tropic could de polarize |
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| 23:25 | south like in nicotine, a casino and most karina castillo Colin will have |
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| 23:29 | polarize the south So they're opposing actions that posson optically they mean a different |
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| 23:36 | to the stuff and puttin it would've binds Pazin optically means deep polarization. |
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| 23:43 | glutamate binds metal. A drop in receptors. It's the opposite is hyper |
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| 23:50 | . So that's why it's signed. synapse meaning that when this photo receptors |
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| 23:55 | polarized the metabolic tropic bipolar saul is to be hyper polarized downstream the synapses |
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| 24:06 | conserving. So hyper polarized means it's to be hyper Poland in the light |
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| 24:14 | shut down due them and release. glutamate release on the amp kinase side |
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| 24:21 | hyper polarization. I mean no glutamate hyper polarization here on the opposite |
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| 24:28 | Metal tropic no glutamate means deep polarization through g protein coupled cascade the metal |
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| 24:37 | tropic glutamate is inhibitory. So this is hyper polarized but the sign inverting |
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| 24:44 | cell is deep polarized and now this himself is also de polarized and that's |
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| 24:55 | this is an on center game So the lightest hyper polarization. And |
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| 25:02 | this circuit in fact that it causes polarization of ganglion cells and through metal |
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| 25:09 | tropic pathway the light which is a polarization of photo receptors actually causes deep |
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| 25:16 | . Yeah so now you see how basically the same stimulus. It's the |
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| 25:21 | stimulus but it's just the circuit that that information. And then organization of |
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| 25:28 | receptor salis is like a camera. you organize your little camera compartments. |
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| 25:35 | cellphone someday we'll have like 200 little cameras on them, all of |
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| 25:40 | . So this is how each one them is like a tiny little camera |
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| 25:43 | at a tiny little spot in the . You know so you have photoreceptors |
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| 25:51 | . So circuit signed conserving is plus deep polarization means the polarization sign. |
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| 26:00 | means deep polarization equals hyper polarization, in the cone equals hyper polarization. |
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| 26:07 | then you can answer these questions so can play around. But the two |
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| 26:11 | important things to remember is what does due to further receptor. And if |
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| 26:17 | study receptors communicating to the arena tropic . So on medical tropic bipolar. |
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| 26:23 | if you know these two things you'll able to answer all of the questions |
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| 26:27 | it's on off the polarizer hyper polarized not necessarily like straightforward and simple but |
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| 26:34 | it's not overly complicated. The circuit you'll say like it's all excited to |
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| 26:40 | so far blue team mates. So receptors bipolar cells would remain federal gang |
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| 26:47 | . Inhibition comes from these horizontally controlling horizontal circuit control through horizontal and american |
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| 26:56 | . And this is an example of cell. The horizontal cell when the |
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| 27:02 | photo receptor is activated in the light signed. Conserving meaning that in the |
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| 27:11 | this cone is hyper polarized and this solace hyper polarized. Oh this horizontal |
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| 27:21 | feeds back, it has a negative projection onto the cone photoreceptors cells. |
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| 27:30 | meaning and it's also signed inverting. when this horizontal cell is D polarized |
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| 27:36 | going to release Gaba the sign inverting actually going to hyper polarized to |
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| 27:44 | So then you say ah that's interesting you told us in the dark the |
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| 27:49 | are deep polarized and dark when the are d polarized. You have this |
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| 27:54 | cool level of regulation by inhibit 30 feedback de polarize is a little too |
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| 28:01 | . There's a little bit more inhibition and there's a little bit more inhibition |
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| 28:06 | the polarization of the cone photoreceptors. there's local level control of these receptive |
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| 28:14 | and member and potentials and you have tight control by inhibition. You have |
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| 28:22 | anatomy of horizontal self inputs responsible for antagonism. Okay so these boundaries between |
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| 28:32 | center and surround and the boundaries between receptors. Fields of these cells are |
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| 28:39 | large part defined by inhibition and inhibitory . You know we think about the |
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| 28:46 | as being sculpting sculpting to find edges that flashlight beam and without inhibition the |
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| 28:54 | beam is more kind of like elusive spread out around. Uh huh. |
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| 29:00 | that's one way you can think about . The other thing is important actually |
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| 29:05 | the circuit is that or sandals south gaba. Uh And horizontal cells also |
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| 29:18 | gap junctions. So what do you about gap junctions? We actually remember |
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| 29:23 | a bit about gap junctions there. junctions. And that means that a |
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| 29:28 | of light that deep polarizes locally and polarizes horizontal south locally will be spread |
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| 29:36 | the circa very quickly then synchronized very through the gap junctions. So this |
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| 29:43 | what the retina is seeing. Okay is the gap junctions are gonna control |
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| 29:49 | not only the sculpting properties but also spread of life and the dilution. |
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| 29:55 | you may have a really strong beam light is also in a way protective |
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| 30:00 | in this negative feedback loop. And in the structure of the circuit for |
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| 30:04 | the controlling the tightness of that beam how it should become more spread out |
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| 30:10 | potentially prevent the burnout. But the receptor cells in case there's strong beams |
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| 30:16 | light that are concentrated. Okay. the last section after the photo |
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| 30:28 | Now you understand the structure and a , you understand structure of the |
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| 30:35 | You understand the circuit in the You understand that there is certain neuro |
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| 30:43 | of that circuit and connectivity. A neurochemistry release of neurotransmitters and neuro pharmacology |
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| 30:50 | the tropic Russia's meddling tropic, there's transaction and the receptive field properties and |
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| 30:57 | information. There's some of the same for you to review. That information |
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| 31:03 | not all that is happening at the of the retina. So the receptive |
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| 31:08 | that are coming from these on and receptive fields from retinal ganglion cells. |
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| 31:13 | coming from the photo receptors clumps of photo receptors through the circuit that's where |
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| 31:18 | on or off. But retinal ganglion themselves are different. This P and |
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| 31:25 | M ganglion cells P stands for They're small cells with small projection trees |
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| 31:32 | have small receptive fields with slower conductance they're less sensitive to low contrast and |
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| 31:39 | cells which are large. They're faster large dendritic tree and there are more |
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| 31:47 | to low contrast. That makes Smaller cells smaller than Reddick projections. |
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| 31:53 | will acquire information from less of these receptors. To some of these fields |
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| 32:01 | going to be smaller in size and will be larger as science. |
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| 32:10 | Depending on where the light is being , these fields are actually overlapping with |
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| 32:15 | other to so what is not in . Type. Non in P. |
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| 32:21 | are the south that don't qualify an korean functionally to be either the power |
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| 32:27 | the magno cells. Now when we into the central processing will be able |
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| 32:37 | understand that we perceive these patterns, we perceive these basic patterns and that |
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| 32:44 | is a really strong patterning and anatomical patterning as you see along this system |
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| 32:53 | . I will talk about the ocular columns and the plasticity in a few |
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| 32:59 | , but before I leave you I want to tell you you had |
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| 33:02 | few distractions. So I'll go over five more minutes. We're going to |
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| 33:07 | looking at where these projections go from retina and 80 to 90 projections from |
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| 33:12 | retina go into the lateral nucleus of , 10% going through the satirical Oculus |
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| 33:20 | the text. Um remember texting and momentum and you remember text um contains |
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| 33:26 | structure called corporate quadra gemini. two Ecology, Provisional Information to Empirical Equality |
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| 33:34 | Auditor Information. So that's where that travels. And the superior calculus is |
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| 33:40 | for faster Katic eye movements. We have a smooth pursuit. And every |
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| 33:45 | you follow somebody moving across across the field or soccer field, you're constantly |
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| 33:51 | these jumps and refocusing on that even if you're moving your head, |
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| 33:56 | that person is going to be shifting and out of distance, making your |
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| 34:01 | and the lens uh basically adjusted to that person and focus the caddy key |
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| 34:08 | . Always say one of the best is in cats, you have a |
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| 34:12 | at home, they'll be sitting and be doing these like thinking thinking, |
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| 34:16 | like bounce, bounce movements, there's , car movements and very well developed |
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| 34:21 | in in in cats 1 to 3% retinal projections and stuff that come out |
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| 34:26 | here in the optic nerve here go the super charismatic nuclear super charismatic nucleus |
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| 34:32 | your master body. Clock is responsible circadian rhythms controlling your diurnal or day |
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| 34:38 | night rhythm. So it receives a input of life. It's not processing |
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| 34:43 | information but obviously some of the brain component like psychotic eye movement. Important |
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| 34:52 | evolutionarily for survival, keeping things in , moving. Ocular motor nerve, |
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| 34:58 | the eyeball. It's there the system there this is what we're seeing here |
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| 35:02 | pretty colors and things like that and and interpretation. That's all. Neocortex |
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| 35:07 | from higher centers. Super charismatic nucleus that light input. It doesn't process |
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| 35:12 | light input. It just it just super cosmetic nucleus date tonight, twilight's |
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| 35:21 | , lighter that's all it needs to and then it regulates the transcription factors |
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| 35:27 | regulates our rhythms so that you wake in the morning and go to sleep |
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| 35:31 | night. The nerve that comes out the eye is the optic nerve to |
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| 35:36 | you have the optic eye ASM so and nasal portion after retina will cross |
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| 35:42 | through the optic eye as subsequently you have optic tract on both sides. |
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| 35:47 | will contain inputs or outputs from the parts of the boat less than the |
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| 35:54 | eye And it is chi asthma Sitting here next to the stock of the |
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| 36:01 | gland. We mentioned the twitter guan HP. A access to remember hypothalamic |
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| 36:10 | adrenal axis. So it's involved in regulation and cortisol regulation. And we'll |
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| 36:18 | into examples when if you have engorged gland or damage or uh growth around |
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| 36:27 | gland, you will also start pinching damaging off the cars, causing certain |
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| 36:34 | of visual laws in general. The of view is divided into the left |
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| 36:40 | right hemisphere. The nasal fibers that closed here to the nose are the |
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| 36:46 | that cross over through the chaos and temporal fibers that are close to the |
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| 36:51 | . The retinal fibers are almost divided half will stay up so laterally on |
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| 36:55 | same side. This region here in middle, depicted right here. If |
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| 37:01 | fix it straight ahead is bipolar That means that both eyes are seeing |
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| 37:07 | area right here. The last i seeing the left periphery because right in |
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| 37:15 | shape like a cop like this. it's sitting like this. And so |
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| 37:21 | bent a little bit. And so receptors here, they will be looking |
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| 37:26 | there. Okay. And so only eye, the left eye and the |
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| 37:32 | in the left eye is going to able to see the periphery on the |
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| 37:36 | because the right I will not be to do it because of the |
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| 37:41 | The nose gets in the way and off the vision actually. So the |
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| 37:48 | periphery is again pursued by the nasal and that nasal component here you can |
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| 37:55 | the dots actually crosses over. The to refer is perceived by the right |
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| 38:01 | component that work This one. And it is also again the part |
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| 38:08 | crosses over. So I will end but when we come back we're going |
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| 38:15 | review how damage to the nerve, optic track and the chasm causes loss |
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| 38:22 | visual field. We will talk about in the thalamus and the six layers |
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| 38:27 | the thalamus. And then we'll finally about and remind ourselves about the anatomy |
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| 38:34 | the cortex and the cortical and laminar in the cortex. So we have |
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| 38:40 | half an hour of material to cover thursday and then I'll be happy to |
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| 38:46 | any questions or walk you through some or show you on all the video |
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| 38:51 | exam. Review if I find a good patch that explains something really |
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| 38:55 | So come prepared back on thursday I'll you here or I'll see you on |
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| 39:01 | and please register for your exam. have a good afternoon |
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