© Distribution of this video is restricted by its owner
Transcript ×
Auto highlight
Font-size
00:00 Welcome back. This is lecture team up very briefly discussing the structure of

00:08 C. N s now that you studied the intricate details of neurons and

00:15 and synaptic transmission. Now you're placing els and communication of these cells through

00:24 neurotransmitter systems within the complex structures off brain within the nuclei without the interconnected

00:34 structures and even comparing it's too other , which what we call comparative neuro

00:43 when you compare the development on the and function of the complexity of different

00:52 areas across different species. So once walked through the brain way, we

01:01 a lot way learned a lot. learned a little bit about the brain

01:07 . We learned quite a few about a few brain structures. We learned

01:12 this cortical organization, which will come again. If you recall it's both

01:18 . It's organized in six layers as . It's columnar where you have these

01:23 and micro columns that connect the south the columnar fashion, and these cells

01:30 these micro columns process similar the same of information that is then communicated long

01:37 through lateral connections. So there's this collectivity and this neocortex, which allows

01:44 parts of the neocortex to interconnect. at the same time, you have

01:50 in this cortical circuits and in the you have these canonical circuits of excited

01:55 an inhibitory cells and redundancy in the of architectural er the fact that you

02:03 six layers independently off where you take little peace, a little plug of

02:10 new cortex from viewed from occipital temporal lobe or pre frontal lobe still

02:17 six layers. The thickness might be , but some of the canonical circuits

02:21 sort of economical signaling and functioning between to inhibitory cells. This is,

02:28 , replicated across different New York cortical . Mhm. So we then reviewed

02:40 parts of the C. N We talked about the cranial nerves,

02:50 I think everyone did really well on on the cranial nerves. And you

02:55 another slide with little Bugs Bunny images you on your exam with these cranial

03:05 . And, uh, the only I'd like to add before we finish

03:10 particular material is discussion on the spinal for a few minutes, noting that

03:20 already mentioned that the spinal cord. vertebra. Aziz. Well,

03:25 the spinal nerves that exit out in the vertebrae s of the material column

03:33 the spinal cord. That's basically like bone that wraps around that.

03:38 you still have the three men in , so we'll surround it. You

03:41 the the super spinal fluid and also bailing, especially through the central

03:50 So the spinal cord is divided into cervical and you have the first cervical

03:56 . The corresponds thio exiting out right the first cervical vertebra. See Juan

04:04 all the way to the seventh cervical and the eighth cranial nerve exiting underneath

04:12 seventh cervical vertebra. So you have cervical nerves and seven cervical vertebra.

04:22 you have 12 thoracic nerves on 12 vertebra through thorax. T one from

04:31 to T 12 over here. Once reach T 12, then you are

04:38 into the lumber area. Lower back area lumber vertebra L one located

04:48 and first lumber nerve exiting out And you can see that at

04:54 uh, level where you have vertebra the spinal nerve exiting it corresponds,

05:03 that particular area of the body and lower part off the spinal cord sub

05:11 the lower extremities and the lumber area serves the nerves and the lumber area

05:19 and the around belongs in the thoracic . So, uh, the lumber

05:28 is here and then you have fifth nerve l five. And what you

05:38 is that by the time you get the fifth lumber vertebra and you have

05:44 fifth lumber nerve coming out the spinal , there is no longer one continuous

05:54 . But it is rather like a that is referred Thio as called a

06:03 , the Qana equine for horses called caudate for tail. Okay,

06:12 everything can be translated and deciphered. versus Rasta row. So Korda tail

06:23 Equestrian Club Queen A horse's tail. this is called a Qana, where

06:31 spinal cord from being one continuous large , splits out into multiple ah,

06:42 , individual nerves exiting odd in between lumber, lower lumber vertebra and between

06:53 sacral vertebra. So you have also vertebra. Finally, the saco

07:02 So this is important because the spinal proper that proper one continuous cable stops

07:11 about l two l three, number , number three. Okay, so

07:20 means then the significance of this, if you ever heard of the spinal

07:28 procedure and you would do a spinal because you would want to, for

07:34 , sample the cerebrospinal fluid. So you have an infection off the

07:44 if you have an infection of the such as, for example,

07:51 Hey, in the cases of you will undergo a spinal tap,

07:59 means that a needle oh, is to be inserted through the back.

08:06 it is usually done around l 345 because the needle that is being inserted

08:17 this area is actually a soft needle that that needle could squeeze in between

08:28 nerves as opposed to damaging the continuous cable tissues squeezing between the nerves and

08:37 some of the cerebrospinal fluid coming here the spinal canal. Mhm. So

08:46 in anesthesia, you remember, you have dura mater. You have

08:55 . We talked about dura mater. hard mother is one of the

09:00 the main meninges. So we talked subdural, so we talked about subdural

09:07 , uh, coagulation and blood damage Duerr. Oh, epidural. There

09:16 epidural injections that might be done for purposes. Epic duro on Those would

09:24 also done on the lower back. to numb the females, typically from

09:32 the delivery process, from pain in in the lower back and,

09:39 lower extremities during the birthing process. , so when be doing at the

09:48 ? It is different from spinal You actually injecting? Ah, a

09:54 anesthetic that is targeting the lumber, central portions off the body and and

10:05 nerves. Okay, so remember that have this division. This is

10:12 Well again. Come up on exam . Just because we didn't cover it

10:18 exam to I didn't want to miss . So you you embed this image

10:22 your hand. You really understand the cord. The divisions of the spinal

10:30 recognize some of the key organs, , kidneys, uh, their locations

10:37 respect Thio some of the nerves that traversing in this anatomical areas, and

10:45 already know this very well. we know that dorsal root ganglion cells

10:51 a DRG so much will send the wants into the dorsal areas and this

10:58 looking, butterfly like pattern is this and surrounding the so HMAS In the

11:06 cord, you have white matter and air, mostly ascending and descending

11:16 LOTTO columns They're sending and descending connections sending either to the cerebral cortex or

11:24 descending from the cerebral cortex and cerebellum palamos back into the spinal cord.

11:30 here is the middle of the spinal that surprise supplies the cerebrospinal fluid,

11:38 the dorsal horn okay, you'll have entry off the accents and on the

11:46 horn is where you'll have the The motor neurons will put the

11:54 and that output will come out eventually the same bundle that will shape and

12:02 one spinal nerves. So these will dorsal root ganglion cell Selma's and they

12:09 back Sants. And then this is ax on bundle from, uh,

12:16 horn motor neuron output. Joining this half Aaron's versus the firings, performing

12:26 single spinal norm at each vertebral a vertebra. Okay, so again you

12:37 the spinal dura matter. You have rack, Lloyd's of Barack Annoyed

12:42 and you have the Spinal Pia mater the spinal cord from the injury of

12:48 it. Being flexible is you bend spine and you bend your spinal cord

12:56 little bit that meninges also move around duh protected and cushion it. So

13:04 you look at the pathways, what see is major major sensory information is

13:14 through the dorsal column and not so dorsal information comes in here.

13:21 sensor information from the body comes in your hands from your shoulders, from

13:28 torso comes down and the travels up inform the cerebral cortex that somebody stopping

13:38 on the hand. I have a on my leg and add information ascends

13:44 travels up through the door, so So you have the left the right

13:52 . So columns here now on the side here. Eventually, you also

14:00 one spine off thalamic tract shown So these air the sending sensory pathways

14:08 mostly dorsal column and then spinal which is from spine to follow

14:14 is located. Um, eventually. , descending pathways are motor pathways,

14:25 information a sensor. Information the descending as motor output. Move your hand

14:33 or into your hand, or fix that is uncomfortable or there's too much

14:41 on my back. I have thio , so this is all motor

14:47 You have the lateral pathway, the medial path. So through the lateral

14:55 you have quoted coast spinal track from to spine. Rubio Spinal Track from

15:02 ruber nuclei measure very little across the spinal tract. Active spinal track from

15:09 in to spy planting. Wreck particular track that stimulus spinal track from the

15:17 Peratis, the spinal tract, which essentially the stimulus which influences the movement

15:24 and the balance of that movement in range. So you don't have to

15:30 the names of the descending motor but you have to realize that you

15:35 have to know this. Sending sensory is the dorsal column or located where

15:40 sensory input is coming in on the side, and this is ascending

15:46 And apart from the spinal thalamic all of the descending information is located

15:51 and this lateral pathway, as well venture immediately so ventral side and on

15:58 midline side, off spinal cord. you can see, these is basically

16:05 bundles that carry information from different parts That information from Ponting from Tacked,

16:15 from cortex. Okay and so This is automatic A This They're all

16:26 nervous system and we don't have Thio, cover it. I still

16:31 an image in there and we'll come to talk about image ing, But

16:36 let you know that in the brain have basically two types of image ing

16:44 you can do noninvasive left. by that I mean that one type

16:51 image ing it's static. It's just image the anatomy of the brain.

16:58 , so such image ing is X or computer tomography, which is a

17:07 , extra emerging onda. There is imaging, functional and Marie, and

17:21 is magnetic resonance in the chain, is based on hydrogen atoms and no

17:30 X ray. We'll get into more when we actually review this in a

17:35 bit more detail. I'll show you techniques in experimental techniques of clinical techniques

17:41 which we can image brain activity and of brain networks so you can have

17:49 static C t, which is computed . So when you say, what

17:55 you doing? You're getting extra or t scan. You will hear that

18:00 in the clinical setting CT scan this tomography Mariah magnetic resonance images, and

18:07 may hear something like this functional. doing functional imaging of the brain.

18:12 does that mean? So versus just ing the structures of the brain actually

18:18 ing the function inside the brain without the skull open without doing a massive

18:24 Trumper nation or, in any other , opening the brain portion so that

18:30 can look through in depth, improve imaging. We have Pat, which

18:37 positive on emission tomography in functional, Marai on and functional imaging instead of

18:46 image ing. What are the changes the structure? Let's say just detecting

18:51 tumor with computer tomography, you want see how that tumor effects activity,

18:58 broad the fact of the tumors and of the brain. So if you

19:04 see a dark spot in the which indicates the presence of tumor,

19:10 doesn't tell you how it affects the of the brain. And so when

19:15 looking at functional image ing and when thinking about activity of the brain,

19:23 very active neurons and the more active neurons, iron and networks, the

19:29 blood they will drawn to that specific and the mawr sugar, the more

19:42 and the more oxygen it will So the regions of the brain that

19:50 active, they need mawr oxygen, of me, They need more supplies

20:03 or need more nutrients. Glucose. they're processing that. And they're generating

20:14 teepee to drive activity and keep up the activity and metabolism and those brain

20:21 . So the functional imaging is really at how much of that area of

20:26 brain is consuming now, how much is going on in that particular area

20:33 the brain? So for Emory in , you're looking at the hydrogen

20:42 which is jumping between high energy and energy state. Okay, one

20:50 the frequency at which this jumping is , at which the slow state protons

20:58 energy is called resonant frequency. So frequency off this switch from low to

21:07 energy state is the resonance frequency And big coils? It looked like this

21:16 get placed in the case of I r m r i or pet

21:22 or CAT scans, but in this , the functional imaging and the ever

21:28 , your picking up radio waves emitted protons. Mhm. So this shows

21:39 that you can do cross sectional analysis the brain that you can look from

21:46 locations and identify whatever area of interest the brain is the reason why you

21:53 these coils so you can have so different directions and measurements and get placed

22:00 the computer computer tomography computed tomography. really tomography is a very sophisticated X

22:09 that is done in a coil like . So you're taking now hundreds of

22:15 about 100 microns, thick ourselves through parts of the brain and then reconstructing

22:21 in this three dimensional image of the . So, for for a pet

22:29 and emission tomography, you have radioactivity that you inject with positively charged ions

22:36 bloodstream and protons bind electrons and the electromagnetic radiation in the form of the

22:45 . And so what you're looking for really glucose consumption or to deok sick

22:53 . So pat is doing to dioxin okay, and you are injecting a

23:04 will solution. But you're then picking with FM Marai. What you're doing

23:12 there's no radioactively labeled solution. You looking at oxygenated hemoglobin or oxy hemoglobin

23:23 de oxygenated hemoglobin. Um, and looking at the ratio. Why?

23:30 the Mawr active is neuronal network, more oxygen the network is going to

23:40 . So the more it's going to oxygenate and turn the oxy hemoglobin into

23:48 CMA globe. And it's gonna be ratio in the active regions and also

23:55 different speeds by which this ratio of versus D oxy hemoglobin is going to

24:02 changing after Laurent. So what you do with functional imaging here is

24:11 pet image ing showed you have a condition whatever your stimulus might be.

24:22 you may be stimulating, uh, visual area. Let's say eso you're

24:30 presenting something to the person while the head is in this coil, that

24:38 or or or magnet coil from This simulation and then this is control

24:46 is is the brain activity and the areas are the areas that are active

24:52 a particular stimulation during a particular and then that task is no longer

24:58 . So this is a control What you can do now in a

25:03 simple way. But it actually happens a very mathematically sophisticated 34 dimensional

25:11 You subtract the image of the brain activity during stimulation from control activity,

25:21 the difference that you get tells you difference that relates to this particular stimulation

25:30 . In In this case, if maybe showing a visual image and the

25:37 alone, maybe you are activating exhibit . Yeah, So this is,

25:47 , something that you know has done a very sophisticated level. This is

25:51 very simple example, but you can that combination of these techniques are very

26:00 . And they may be very important techniques, especially in neurodegenerative and neurological

26:08 . That's a Marai together with the G or electrons of follow. Graham

26:12 be used to definitively determine the full , the focus off off groups,

26:23 focus or the full side off the activity source. So there might be

26:32 small area in the brain, and want to locate it. And with

26:36 g. If you remember as electrons hologram, you place electrodes on top

26:41 the skull. Now, with the ing and functional imaging, you could

26:46 inside activity of the skull naturally, to locate more precisely, the location

26:53 the brain or the network in the that it's mostly dysfunctional on is responsible

26:59 generating abnormal seizure epileptic like activity All right, let me pause here

27:09 a second. So now we're moving the visual system and I am using

27:19 slide to show you what looks like complex, interconnected network off cells.

27:33 will be all understood by you by time we go through three lectures on

27:41 individual system. But today we will with an I and one other reason

27:49 showing you The slide is to show that outwards from the in the form

27:55 optic nerve and later in the form optic track, innovate L G

28:03 which is a lateral Jinich elit nucleus the foul months. And it has

28:09 layers. So it's a pretty sophisticated , this nucleus in the following months

28:16 this nucleus and the 1000 Muslim will send the signal from the column us

28:23 visual information that came from the outside into the retina into the Thala.

28:29 will then be sent to the one is the primary sensory visual processing area

28:41 , and in the one that information going, thio diverge into two streams

28:49 two pathways one pathway going to the parietal posterior parietal cortex that is called

29:00 parietal pathway. Another possible from the similar low from the V one area

29:09 the two. The three before will thio the ventral to inferior temporal

29:20 the eventual inferior temporal pathway. let's remember that this visual information gets

29:30 in the retina in the Solomon's before reaches the primary visual cortex.

29:37 increasingly, it gets more complex, increasingly building a fuller picture of the

29:44 visual view. But the whole world you're observing, or the image that

29:52 observing and then the pathways divergent to dorsal pathway and eventual pathway on dorsal

30:05 will be emerging. This visual information a sensory experiences are parietal cortex and

30:13 pathway mawr. With the auditory experiences are located, uh, in the

30:21 lobe, I'm so these would be areas, then, where the information

30:30 multiple census the hearing and vision get together and then give communicated across other

30:37 areas and forming the complete sensory and response off the body. But to

30:49 with, we can start with something is an introduction to the visual

30:59 um, German term of gestalt, reform. Or if you may,

31:08 picture of complete you and this the way it comes, is what

31:14 see in the outside world. Is observing the screen now? It represents

31:22 off the objects. So there are properties I have hands. Those hands

31:27 about the size compared to my And so you know, certain properties

31:36 the objects, and then the reason you see them in a certain way

31:41 the reason why we observe them similarly all of you see in my hands

31:45 about the same size is my face because we have very similar organization off

31:55 architecture er of new normal networks and organization off sensor information processing by the

32:06 . Uh, so that's why we certain things in the same way.

32:15 , uh, there's also things that see exactly the same. And that's

32:23 our anatomy is built very, very so. Three dimensional experiences that are

32:31 from two dimensional images. Right now looking at the flat screen, which

32:39 really thio dimensions, and you're looking at my image moving around now,

32:45 is in two dimensions. But maybe gives you more dimension. Now you're

32:51 , Oh, now he's far His hand is closed, his base

32:56 close, and so but it's still dimensions, right? But you don't

33:03 that I'm flat, you know, ? You don't think I'm flat because

33:10 I turned, actually, you have depth to me. This is

33:14 not just flat like I am on two dimensional screen, but we organized

33:19 two dimensional pattern sensations into stable gestalt . You're not even thinking like you're

33:25 . He's sitting these two walls around . There's a lamp. There's a

33:31 a perspective going on that way, that everybody seeing this is organized,

33:39 it's all flat. But do you that this lamp is behind me because

33:43 can't even region? Okay? You knew that without me even reaching for

33:52 . You already organized this into a pattern, Thio stalled, and it's

33:59 despite the variation and information received. other words, because my hand is

34:05 in front of you now. It mean that my hand is now five

34:09 the size of my face. The of my hand hasn't changed. You

34:16 suggested it. You're like, his hand is really close. You

34:20 say, Well, God, he's a humongous hand on the right and

34:24 left hand is so much smaller. know, this is all of the

34:30 that you're observing, but you're keeping constant. It doesn't alarm your

34:40 It doesn't alarm you to say what's on. Huge arm, You

34:44 it's despite variations and information received despite light changing. If the light change

34:51 something and my colleges on the phase blue, you would probably look at

34:58 and say, Well, he really probably turn blue. Maybe it's a

35:02 . Or maybe it's the curtains blew reflection. So you would you would

35:07 have things that even observing you would say no. But maybe I did

35:11 blue. Maybe I'm not feeling I'm just turning blue or green so

35:16 brain makes or read the brain makes assumptions about what is to be seen

35:23 the world, expectations that seemed to in part from experience. So we

35:28 certain experiences if I if I move hand close so you know it's going

35:33 take up the whole screen. And off course because of the built in

35:41 wiring for vision, very intricate, wiring system that exists revision very

35:51 intricate circus from the retina to the cortex to further down the association

36:00 And we do things. We already certain things. If we take this

36:04 pattern and a it's a vigorous pattern biggest in the sense that you really

36:11 tell if these circles are organized in or and columns. Now, if

36:25 look in B, I would ask , what does this represent? Be

36:33 top and you'll say, Well, blue rose. Five. It's

36:42 yellow, blue, yellow, yellow roh. No, I think

36:47 it's blue columns and yellow columns, columns, yellow columns, blue

36:55 yellow columns. And if you look this image, my brain tells me

37:00 yellow. Roast blue rose, yellow , blue row, yellow row,

37:06 row. That's just a Nasaf option we make because of the similarity.

37:14 group yellow together, we group blue , and if somebody went to ask

37:21 , will say, Well, this columns and this is Rose. In

37:27 , it may not be in It maybe rose off blue and

37:33 blue and yellow, blue and But your brain, your visual organization

37:41 the way that you're seeing these patterns based on this principles of similarity,

37:46 grouping things together similar in color, principles. Proximity. If you looked

37:56 the image here on the right, would say off course it zits columns

38:01 dots. And if you looked on bottom here, you say it's rows

38:06 dots. But that may not be case. We were doing that because

38:12 we see it. And that's because the proximity so thes air closer to

38:19 other, vertically and further away from other, horizontally. So we immediately

38:28 , Well, there's got to be column. This these air all group

38:32 together and proximity principle tells us this called. Likewise, here. Here

38:41 distance is closer horizontally as opposed to e. So we say immediately,

38:47 on this proximity encoding in a way , okay, these arose of blue

38:57 . Of course, they have a of different delusions. This is just

39:03 know this line that if you took these blue lines, who would think

39:08 number two is longer because it has arrowheads that are outward versus the arrowheads

39:17 go in. Likewise, as you , this is not an illusion.

39:23 , you know, again that I become much bigger. I didn't become

39:27 smaller and shrunk to three feeds because moved away. So we make certain

39:37 . There's a lot of different illusions some of the once that were in

39:43 . So it's the vase illusion. see a vase of people see two

39:47 facing each other to noses here This is the one that it's not

39:53 up very well, but it's a yellow on frogs and green, and

39:58 other thing about the illusions. Once see them, you learn them.

40:02 you can pick them up very Some of the complex illusions may take

40:06 a few seconds to realize what you're at. But the next time you

40:11 and you see that same image with same illusion, that will be less

40:15 a second. Like I know I've seen this before. You

40:18 we constructed in your brain much, faster. So what are we looking

40:23 ? Where we're looking at these different we're looking at light on and

40:31 which is electromagnetic radiation, which has wavelength, uh, frequency that will

40:41 that wavelength and certain amplitude, which be the strength of that particular lighter

40:47 you wanna call it luminous when you're light about how many lumens will be

40:52 amplitude of how how how bright that can shine for example, within a

40:59 wavelength. So our electromagnetic radiations that absorbed and perceived by our eyes fall

41:10 the range of 400 to 700 This is the wavelength in nanometers,

41:19 the visible light in the visible spectrum , orange, yellow, green,

41:28 , indica violent. So the shortest violent and shorter than 400 nanometer

41:38 our ultraviolet rays and even shorter than . Our X rays and even shorter

41:48 wavelengths are gamma rights. So if look on the other spectrum on the

41:57 , which is 700 nanometers longer wavelength is infrared race. Then you have

42:08 race that are very long way length you have broadcast bad broadcast bands.

42:15 you have a C circuits. So visible light range I'm sure you may

42:22 from maybe chemistry in high school, G. Bev Roy G. Dev

42:32 the longest Red, orange, yellow , the ivy he is.

42:40 swell, gentlemen. Roy G. Roy Red, orange, yellow,

42:46 , blue Indigo Violence can never forget Roy G did just have to remember

42:51 Red Roy is the 700 nanometer read , and then you have in for

43:00 . And if you think about I want the What is the

43:04 You know, ultraviolet is on that . Okay, so the slide that

43:11 the eye, what happens is a of light can get reflected, and

43:16 does from different surfaces could be absorbed different surfaces that the surfaces light white

43:23 will reflect a lot of line black will absorb more light. And

43:30 once the light hands a different medium air to water, then you have

43:37 bending the rays of light, which referred to as refraction. So that

43:45 enters into the pupil. This is pupil right here, Eyeball. This

43:52 your eye. This is the Irish the pupil on this Is this Clara

43:58 the iris, and then you have extra ocular muscles. Here. You

44:05 , the ocular muscles are ocular motor , ocular muscles, movement off the

44:14 movement off the eye muscles. You the cornea here in front,

44:19 And then in the back, you the retina and the optic nerve that

44:24 out off the I. So once exits out of the I one more

44:30 , that goes into the solemn this L g m and from Thala mus

44:34 L g m. It gets sent the primary visual cortex in the occipital

44:44 . Here you have your locker All glam that is going to generate

44:48 tears. Um, canal for for drainage. Here again, the

44:53 the irises. Claire surrounding it. is a side view oven eyeball,

44:59 you may. It was cut through sagittal plane. And what you're seeing

45:06 is you're seeing the cornea on the surface here. Okay, you're seeing

45:16 you have the acquis humor which sits in front, off the iris and

45:26 pupil. So there's this cushion here fluid that's sitting between the cornea and

45:38 and the pupil and behind the which is essentially a little shudder that

45:47 the enter into the light. And can close that shutter and make it

45:52 , and you can open the shutter make it larger. Okay, so

45:57 is what, the pupil, the , And then you have the lens

46:02 , and this lands okay, can thicker or sinner. So this Lance

46:12 suspended and it's held up by the Serie Ligaments coming from Silla. Everybody

46:24 and these suspensive ligaments can stretch. , we can contract and they can

46:34 the lands or they can relax and can bulk up the lens. So

46:41 they contract, the lens will get . And if they relax, the

46:47 will get thicker. And as the gets thinner and thicker, it allows

46:53 the light that comes into the Pew to precisely focus that image precisely on

47:01 retina, which is located in the back off the eyeball have all is

47:08 with the vitreous humor. It's gel liquid substance that gives an eyeball

47:17 keeps up a certain shape off the , and you have the retina in

47:24 back way. Have the muscle. the moving the eyeball on the movement

47:31 the eyeball will move the eyeball, for the eyeball thio look at a

47:38 area in the field of view and for the people Thio let in more

47:44 less light and then for the lens become thinner or thicker as its

47:51 The incoming light directing it on to retina phobia is where you have the

47:58 resolution vision, and it is located in the path of the pupil directly

48:05 the direct rays of light will be and hitting phobia, which is in

48:10 back part of the retina with the resolution photo receptors or the highest special

48:19 . And on the back off the you have optic nerve. So the

48:25 where optic nerve exits out of the is called the optic disc, and

48:30 optic disc is where you would have blind spot because there's no right in

48:35 here in one area where all of output from the retina and the out

48:40 in the eyeball exits out there is object in Europe, and obviously the

48:46 has little blood vessels and micro vessels are innovating the eyeball. And sometimes

48:54 may even see it. If somebody's tired or they may have an inflammation

49:01 or they're running the I two you may see a pop.

49:04 That's all that might be temporarily. you could observe it with with your

49:11 eye as well this little blood Okay, okay, So more and

49:18 and more and more about this is intricate anatomy of the eyeball on the

49:23 of the life, passing indirectly again so that it gets directly on.

49:29 phobia, which has the highest resolution requires the highest amount of light.

49:34 it's both they need each other. needs to hit phobia. Thio,

49:42 us to see the detail in the and phobia needs to be located.

49:47 most lied to come in in order resolve that detail in the world,

49:54 right now has a very specific And in the way, what is

50:00 here is that if you're fixating in point of space, let's say you're

50:04 at a cam and space right. fixating room, this camp and that

50:12 . Looking at the Cannes, let's , in a certain way, your

50:16 , lightest coming in, that's going the phobia and notice What you have

50:21 a polite will. Pass through the through the hole, eyeball the whole

50:30 here through the whole vitreous humor solution it hits the back of the eyeball

50:38 retina, and you have three Three major types of cells here,

50:46 by Poland photo receptor cells and photo cells and actually true, introduce delight

50:54 a photon of light or electromagnetic signal electrochemical signal. They're located in the

51:05 back of the threat middle circuit. it, you have the pigment feeling

51:13 right, so retina is part of central nervous system. Phobia is again

51:20 highest acuity, the highest resolution And most of the time, if

51:25 want to look at something in great , we'll move our eyes around and

51:30 our lenses and focus our vision onto particular object, uh, to resolve

51:37 in great detail, Um, with . So let's look briefly at this

51:45 . There's gonna be more and more as we look into the visual

51:50 the retina, and move up into l G m. But for today

51:56 will learn that again. This visual coming in, which is the direction

52:01 life, will pass through this jungle the cells and synopsis interconnected synopsis and

52:08 gonna then finally hit the photo And you have two types of major

52:15 of types of photos. Separate. rod photo receptors that air a

52:20 We do not process color, and have chromatic cone photoreceptors that's specifically designed

52:28 process blue, red or green color activation of red, blue and green

52:35 various combinations will create a variety of of the visual world on the colors

52:41 you're seeing, and it's quite Toe learn the chickens, chicken.

52:46 actually see a lot more Hughes in world that we can see. Can

52:52 imagine if you have the ability to , like 2000 Hughes versus like some

52:57 100 years that we can see so world is actually the very colorful.

53:05 think about it next time you go Chick fil A, Uh,

53:10 that's a joke. But we do these chromatic, uh, cones.

53:16 that's how activation of different level of , blue and green can give us

53:21 variations and combinations of Hughes and colors we're seeing now that information is actually

53:27 process and photoreceptors and gets communicated to Selves, bipolar cells and send their

53:36 and contact ganglion cells. In they're referred to as either ganglion cells

53:42 retinal ganglion cells because they form a . Off optic nerve fibers exits out

53:53 they go from Ratna into the lateral Nicolas nucleus. So that's why they're

54:00 retina Jinich, Oculus self. They from retina and the optic nerve.

54:07 axles goes into the following us into lateral technical opponents of the followers.

54:14 this is, if you may, kind of ah communication happening from photo

54:21 , bipolar cells and then to the cells that send information through the optic

54:26 into the lateral Jamaica nucleus and the between the horizontal on bipolar cells.

54:33 synaptic transmission is being checked and controlled modulated by south and a cold horizontal

54:40 . And the communication between bipolar south the ganglion cells is being modulated and

54:48 by a McQueen cells. And we learn about the circuitry and greater detail

54:54 these, uh, horizontal and immigrants control on bipolar self communication of that

55:01 as well. Okay, so I for the sake of time, this

55:08 again quite a bit of information that covered today I am going Thio end

55:16 lecture here today and we'll pick up we left off at the next

55:26 So I will check the chat to sure that I can answer all of

55:31 questions and I will see you again

-
+