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00:00 | Welcome back. This is lecture team up very briefly discussing the structure of |
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00:08 | C. N s now that you studied the intricate details of neurons and |
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00:15 | and synaptic transmission. Now you're placing els and communication of these cells through |
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00:24 | neurotransmitter systems within the complex structures off brain within the nuclei without the interconnected |
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00:34 | structures and even comparing it's too other , which what we call comparative neuro |
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00:43 | when you compare the development on the and function of the complexity of different |
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00:52 | areas across different species. So once walked through the brain way, we |
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01:01 | a lot way learned a lot. learned a little bit about the brain |
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01:07 | . We learned quite a few about a few brain structures. We learned |
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01:12 | this cortical organization, which will come again. If you recall it's both |
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01:18 | . It's organized in six layers as . It's columnar where you have these |
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01:23 | and micro columns that connect the south the columnar fashion, and these cells |
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01:30 | these micro columns process similar the same of information that is then communicated long |
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01:37 | through lateral connections. So there's this collectivity and this neocortex, which allows |
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01:44 | parts of the neocortex to interconnect. at the same time, you have |
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01:50 | in this cortical circuits and in the you have these canonical circuits of excited |
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01:55 | an inhibitory cells and redundancy in the of architectural er the fact that you |
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02:03 | six layers independently off where you take little peace, a little plug of |
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02:10 | new cortex from viewed from occipital temporal lobe or pre frontal lobe still |
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02:17 | six layers. The thickness might be , but some of the canonical circuits |
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02:21 | sort of economical signaling and functioning between to inhibitory cells. This is, |
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02:28 | , replicated across different New York cortical . Mhm. So we then reviewed |
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02:40 | parts of the C. N We talked about the cranial nerves, |
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02:50 | I think everyone did really well on on the cranial nerves. And you |
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02:55 | another slide with little Bugs Bunny images you on your exam with these cranial |
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03:05 | . And, uh, the only I'd like to add before we finish |
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03:10 | particular material is discussion on the spinal for a few minutes, noting that |
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03:20 | already mentioned that the spinal cord. vertebra. Aziz. Well, |
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03:25 | the spinal nerves that exit out in the vertebrae s of the material column |
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03:33 | the spinal cord. That's basically like bone that wraps around that. |
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03:38 | you still have the three men in , so we'll surround it. You |
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03:41 | the the super spinal fluid and also bailing, especially through the central |
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03:50 | So the spinal cord is divided into cervical and you have the first cervical |
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03:56 | . The corresponds thio exiting out right the first cervical vertebra. See Juan |
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04:04 | all the way to the seventh cervical and the eighth cranial nerve exiting underneath |
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04:12 | seventh cervical vertebra. So you have cervical nerves and seven cervical vertebra. |
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04:22 | you have 12 thoracic nerves on 12 vertebra through thorax. T one from |
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04:31 | to T 12 over here. Once reach T 12, then you are |
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04:38 | into the lumber area. Lower back area lumber vertebra L one located |
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04:48 | and first lumber nerve exiting out And you can see that at |
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04:54 | uh, level where you have vertebra the spinal nerve exiting it corresponds, |
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05:03 | that particular area of the body and lower part off the spinal cord sub |
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05:11 | the lower extremities and the lumber area serves the nerves and the lumber area |
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05:19 | and the around belongs in the thoracic . So, uh, the lumber |
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05:28 | is here and then you have fifth nerve l five. And what you |
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05:38 | is that by the time you get the fifth lumber vertebra and you have |
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05:44 | fifth lumber nerve coming out the spinal , there is no longer one continuous |
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05:54 | . But it is rather like a that is referred Thio as called a |
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06:03 | , the Qana equine for horses called caudate for tail. Okay, |
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06:12 | everything can be translated and deciphered. versus Rasta row. So Korda tail |
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06:23 | Equestrian Club Queen A horse's tail. this is called a Qana, where |
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06:31 | spinal cord from being one continuous large , splits out into multiple ah, |
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06:42 | , individual nerves exiting odd in between lumber, lower lumber vertebra and between |
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06:53 | sacral vertebra. So you have also vertebra. Finally, the saco |
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07:02 | So this is important because the spinal proper that proper one continuous cable stops |
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07:11 | about l two l three, number , number three. Okay, so |
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07:20 | means then the significance of this, if you ever heard of the spinal |
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07:28 | procedure and you would do a spinal because you would want to, for |
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07:34 | , sample the cerebrospinal fluid. So you have an infection off the |
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07:44 | if you have an infection of the such as, for example, |
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07:51 | Hey, in the cases of you will undergo a spinal tap, |
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07:59 | means that a needle oh, is to be inserted through the back. |
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08:06 | it is usually done around l 345 because the needle that is being inserted |
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08:17 | this area is actually a soft needle that that needle could squeeze in between |
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08:28 | nerves as opposed to damaging the continuous cable tissues squeezing between the nerves and |
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08:37 | some of the cerebrospinal fluid coming here the spinal canal. Mhm. So |
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08:46 | in anesthesia, you remember, you have dura mater. You have |
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08:55 | . We talked about dura mater. hard mother is one of the |
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09:00 | the main meninges. So we talked subdural, so we talked about subdural |
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09:07 | , uh, coagulation and blood damage Duerr. Oh, epidural. There |
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09:16 | epidural injections that might be done for purposes. Epic duro on Those would |
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09:24 | also done on the lower back. to numb the females, typically from |
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09:32 | the delivery process, from pain in in the lower back and, |
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09:39 | lower extremities during the birthing process. , so when be doing at the |
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09:48 | ? It is different from spinal You actually injecting? Ah, a |
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09:54 | anesthetic that is targeting the lumber, central portions off the body and and |
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10:05 | nerves. Okay, so remember that have this division. This is |
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10:12 | Well again. Come up on exam . Just because we didn't cover it |
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10:18 | exam to I didn't want to miss . So you you embed this image |
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10:22 | your hand. You really understand the cord. The divisions of the spinal |
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10:30 | recognize some of the key organs, , kidneys, uh, their locations |
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10:37 | respect Thio some of the nerves that traversing in this anatomical areas, and |
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10:45 | already know this very well. we know that dorsal root ganglion cells |
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10:51 | a DRG so much will send the wants into the dorsal areas and this |
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10:58 | looking, butterfly like pattern is this and surrounding the so HMAS In the |
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11:06 | cord, you have white matter and air, mostly ascending and descending |
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11:16 | LOTTO columns They're sending and descending connections sending either to the cerebral cortex or |
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11:24 | descending from the cerebral cortex and cerebellum palamos back into the spinal cord. |
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11:30 | here is the middle of the spinal that surprise supplies the cerebrospinal fluid, |
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11:38 | the dorsal horn okay, you'll have entry off the accents and on the |
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11:46 | horn is where you'll have the The motor neurons will put the |
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11:54 | and that output will come out eventually the same bundle that will shape and |
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12:02 | one spinal nerves. So these will dorsal root ganglion cell Selma's and they |
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12:09 | back Sants. And then this is ax on bundle from, uh, |
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12:16 | horn motor neuron output. Joining this half Aaron's versus the firings, performing |
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12:26 | single spinal norm at each vertebral a vertebra. Okay, so again you |
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12:37 | the spinal dura matter. You have rack, Lloyd's of Barack Annoyed |
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12:42 | and you have the Spinal Pia mater the spinal cord from the injury of |
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12:48 | it. Being flexible is you bend spine and you bend your spinal cord |
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12:56 | little bit that meninges also move around duh protected and cushion it. So |
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13:04 | you look at the pathways, what see is major major sensory information is |
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13:14 | through the dorsal column and not so dorsal information comes in here. |
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13:21 | sensor information from the body comes in your hands from your shoulders, from |
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13:28 | torso comes down and the travels up inform the cerebral cortex that somebody stopping |
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13:38 | on the hand. I have a on my leg and add information ascends |
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13:44 | travels up through the door, so So you have the left the right |
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13:52 | . So columns here now on the side here. Eventually, you also |
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14:00 | one spine off thalamic tract shown So these air the sending sensory pathways |
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14:08 | mostly dorsal column and then spinal which is from spine to follow |
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14:14 | is located. Um, eventually. , descending pathways are motor pathways, |
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14:25 | information a sensor. Information the descending as motor output. Move your hand |
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14:33 | or into your hand, or fix that is uncomfortable or there's too much |
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14:41 | on my back. I have thio , so this is all motor |
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14:47 | You have the lateral pathway, the medial path. So through the lateral |
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14:55 | you have quoted coast spinal track from to spine. Rubio Spinal Track from |
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15:02 | ruber nuclei measure very little across the spinal tract. Active spinal track from |
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15:09 | in to spy planting. Wreck particular track that stimulus spinal track from the |
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15:17 | Peratis, the spinal tract, which essentially the stimulus which influences the movement |
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15:24 | and the balance of that movement in range. So you don't have to |
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15:30 | the names of the descending motor but you have to realize that you |
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15:35 | have to know this. Sending sensory is the dorsal column or located where |
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15:40 | sensory input is coming in on the side, and this is ascending |
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15:46 | And apart from the spinal thalamic all of the descending information is located |
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15:51 | and this lateral pathway, as well venture immediately so ventral side and on |
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15:58 | midline side, off spinal cord. you can see, these is basically |
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16:05 | bundles that carry information from different parts That information from Ponting from Tacked, |
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16:15 | from cortex. Okay and so This is automatic A This They're all |
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16:26 | nervous system and we don't have Thio, cover it. I still |
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16:31 | an image in there and we'll come to talk about image ing, But |
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16:36 | let you know that in the brain have basically two types of image ing |
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16:44 | you can do noninvasive left. by that I mean that one type |
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16:51 | image ing it's static. It's just image the anatomy of the brain. |
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16:58 | , so such image ing is X or computer tomography, which is a |
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17:07 | , extra emerging onda. There is imaging, functional and Marie, and |
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17:21 | is magnetic resonance in the chain, is based on hydrogen atoms and no |
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17:30 | X ray. We'll get into more when we actually review this in a |
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17:35 | bit more detail. I'll show you techniques in experimental techniques of clinical techniques |
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17:41 | which we can image brain activity and of brain networks so you can have |
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17:49 | static C t, which is computed . So when you say, what |
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17:55 | you doing? You're getting extra or t scan. You will hear that |
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18:00 | in the clinical setting CT scan this tomography Mariah magnetic resonance images, and |
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18:07 | may hear something like this functional. doing functional imaging of the brain. |
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18:12 | does that mean? So versus just ing the structures of the brain actually |
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18:18 | ing the function inside the brain without the skull open without doing a massive |
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18:24 | Trumper nation or, in any other , opening the brain portion so that |
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18:30 | can look through in depth, improve imaging. We have Pat, which |
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18:37 | positive on emission tomography in functional, Marai on and functional imaging instead of |
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18:46 | image ing. What are the changes the structure? Let's say just detecting |
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18:51 | tumor with computer tomography, you want see how that tumor effects activity, |
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18:58 | broad the fact of the tumors and of the brain. So if you |
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19:04 | see a dark spot in the which indicates the presence of tumor, |
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19:10 | doesn't tell you how it affects the of the brain. And so when |
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19:15 | looking at functional image ing and when thinking about activity of the brain, |
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19:23 | very active neurons and the more active neurons, iron and networks, the |
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19:29 | blood they will drawn to that specific and the mawr sugar, the more |
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19:42 | and the more oxygen it will So the regions of the brain that |
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19:50 | active, they need mawr oxygen, of me, They need more supplies |
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20:03 | or need more nutrients. Glucose. they're processing that. And they're generating |
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20:14 | teepee to drive activity and keep up the activity and metabolism and those brain |
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20:21 | . So the functional imaging is really at how much of that area of |
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20:26 | brain is consuming now, how much is going on in that particular area |
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20:33 | the brain? So for Emory in , you're looking at the hydrogen |
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20:42 | which is jumping between high energy and energy state. Okay, one |
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20:50 | the frequency at which this jumping is , at which the slow state protons |
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20:58 | energy is called resonant frequency. So frequency off this switch from low to |
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21:07 | energy state is the resonance frequency And big coils? It looked like this |
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21:16 | get placed in the case of I r m r i or pet |
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21:22 | or CAT scans, but in this , the functional imaging and the ever |
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21:28 | , your picking up radio waves emitted protons. Mhm. So this shows |
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21:39 | that you can do cross sectional analysis the brain that you can look from |
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21:46 | locations and identify whatever area of interest the brain is the reason why you |
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21:53 | these coils so you can have so different directions and measurements and get placed |
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22:00 | the computer computer tomography computed tomography. really tomography is a very sophisticated X |
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22:09 | that is done in a coil like . So you're taking now hundreds of |
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22:15 | about 100 microns, thick ourselves through parts of the brain and then reconstructing |
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22:21 | in this three dimensional image of the . So, for for a pet |
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22:29 | and emission tomography, you have radioactivity that you inject with positively charged ions |
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22:36 | bloodstream and protons bind electrons and the electromagnetic radiation in the form of the |
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22:45 | . And so what you're looking for really glucose consumption or to deok sick |
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22:53 | . So pat is doing to dioxin okay, and you are injecting a |
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23:04 | will solution. But you're then picking with FM Marai. What you're doing |
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23:12 | there's no radioactively labeled solution. You looking at oxygenated hemoglobin or oxy hemoglobin |
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23:23 | de oxygenated hemoglobin. Um, and looking at the ratio. Why? |
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23:30 | the Mawr active is neuronal network, more oxygen the network is going to |
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23:40 | . So the more it's going to oxygenate and turn the oxy hemoglobin into |
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23:48 | CMA globe. And it's gonna be ratio in the active regions and also |
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23:55 | different speeds by which this ratio of versus D oxy hemoglobin is going to |
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24:02 | changing after Laurent. So what you do with functional imaging here is |
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24:11 | pet image ing showed you have a condition whatever your stimulus might be. |
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24:22 | you may be stimulating, uh, visual area. Let's say eso you're |
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24:30 | presenting something to the person while the head is in this coil, that |
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24:38 | or or or magnet coil from This simulation and then this is control |
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24:46 | is is the brain activity and the areas are the areas that are active |
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24:52 | a particular stimulation during a particular and then that task is no longer |
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24:58 | . So this is a control What you can do now in a |
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25:03 | simple way. But it actually happens a very mathematically sophisticated 34 dimensional |
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25:11 | You subtract the image of the brain activity during stimulation from control activity, |
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25:21 | the difference that you get tells you difference that relates to this particular stimulation |
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25:30 | . In In this case, if maybe showing a visual image and the |
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25:37 | alone, maybe you are activating exhibit . Yeah, So this is, |
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25:47 | , something that you know has done a very sophisticated level. This is |
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25:51 | very simple example, but you can that combination of these techniques are very |
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26:00 | . And they may be very important techniques, especially in neurodegenerative and neurological |
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26:08 | . That's a Marai together with the G or electrons of follow. Graham |
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26:12 | be used to definitively determine the full , the focus off off groups, |
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26:23 | focus or the full side off the activity source. So there might be |
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26:32 | small area in the brain, and want to locate it. And with |
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26:36 | g. If you remember as electrons hologram, you place electrodes on top |
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26:41 | the skull. Now, with the ing and functional imaging, you could |
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26:46 | inside activity of the skull naturally, to locate more precisely, the location |
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26:53 | the brain or the network in the that it's mostly dysfunctional on is responsible |
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26:59 | generating abnormal seizure epileptic like activity All right, let me pause here |
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27:09 | a second. So now we're moving the visual system and I am using |
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27:19 | slide to show you what looks like complex, interconnected network off cells. |
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27:33 | will be all understood by you by time we go through three lectures on |
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27:41 | individual system. But today we will with an I and one other reason |
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27:49 | showing you The slide is to show that outwards from the in the form |
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27:55 | optic nerve and later in the form optic track, innovate L G |
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28:03 | which is a lateral Jinich elit nucleus the foul months. And it has |
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28:09 | layers. So it's a pretty sophisticated , this nucleus in the following months |
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28:16 | this nucleus and the 1000 Muslim will send the signal from the column us |
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28:23 | visual information that came from the outside into the retina into the Thala. |
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28:29 | will then be sent to the one is the primary sensory visual processing area |
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28:41 | , and in the one that information going, thio diverge into two streams |
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28:49 | two pathways one pathway going to the parietal posterior parietal cortex that is called |
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29:00 | parietal pathway. Another possible from the similar low from the V one area |
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29:09 | the two. The three before will thio the ventral to inferior temporal |
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29:20 | the eventual inferior temporal pathway. let's remember that this visual information gets |
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29:30 | in the retina in the Solomon's before reaches the primary visual cortex. |
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29:37 | increasingly, it gets more complex, increasingly building a fuller picture of the |
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29:44 | visual view. But the whole world you're observing, or the image that |
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29:52 | observing and then the pathways divergent to dorsal pathway and eventual pathway on dorsal |
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30:05 | will be emerging. This visual information a sensory experiences are parietal cortex and |
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30:13 | pathway mawr. With the auditory experiences are located, uh, in the |
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30:21 | lobe, I'm so these would be areas, then, where the information |
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30:30 | multiple census the hearing and vision get together and then give communicated across other |
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30:37 | areas and forming the complete sensory and response off the body. But to |
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30:49 | with, we can start with something is an introduction to the visual |
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30:59 | um, German term of gestalt, reform. Or if you may, |
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31:08 | picture of complete you and this the way it comes, is what |
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31:14 | see in the outside world. Is observing the screen now? It represents |
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31:22 | off the objects. So there are properties I have hands. Those hands |
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31:27 | about the size compared to my And so you know, certain properties |
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31:36 | the objects, and then the reason you see them in a certain way |
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31:41 | the reason why we observe them similarly all of you see in my hands |
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31:45 | about the same size is my face because we have very similar organization off |
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31:55 | architecture er of new normal networks and organization off sensor information processing by the |
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32:06 | . Uh, so that's why we certain things in the same way. |
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32:15 | , uh, there's also things that see exactly the same. And that's |
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32:23 | our anatomy is built very, very so. Three dimensional experiences that are |
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32:31 | from two dimensional images. Right now looking at the flat screen, which |
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32:39 | really thio dimensions, and you're looking at my image moving around now, |
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32:45 | is in two dimensions. But maybe gives you more dimension. Now you're |
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32:51 | , Oh, now he's far His hand is closed, his base |
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32:56 | close, and so but it's still dimensions, right? But you don't |
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33:03 | that I'm flat, you know, ? You don't think I'm flat because |
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33:10 | I turned, actually, you have depth to me. This is |
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33:14 | not just flat like I am on two dimensional screen, but we organized |
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33:19 | two dimensional pattern sensations into stable gestalt . You're not even thinking like you're |
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33:25 | . He's sitting these two walls around . There's a lamp. There's a |
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33:31 | a perspective going on that way, that everybody seeing this is organized, |
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33:39 | it's all flat. But do you that this lamp is behind me because |
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33:43 | can't even region? Okay? You knew that without me even reaching for |
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33:52 | . You already organized this into a pattern, Thio stalled, and it's |
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33:59 | despite the variation and information received. other words, because my hand is |
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34:05 | in front of you now. It mean that my hand is now five |
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34:09 | the size of my face. The of my hand hasn't changed. You |
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34:16 | suggested it. You're like, his hand is really close. You |
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34:20 | say, Well, God, he's a humongous hand on the right and |
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34:24 | left hand is so much smaller. know, this is all of the |
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34:30 | that you're observing, but you're keeping constant. It doesn't alarm your |
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34:40 | It doesn't alarm you to say what's on. Huge arm, You |
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34:44 | it's despite variations and information received despite light changing. If the light change |
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34:51 | something and my colleges on the phase blue, you would probably look at |
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34:58 | and say, Well, he really probably turn blue. Maybe it's a |
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35:02 | . Or maybe it's the curtains blew reflection. So you would you would |
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35:07 | have things that even observing you would say no. But maybe I did |
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35:11 | blue. Maybe I'm not feeling I'm just turning blue or green so |
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35:16 | brain makes or read the brain makes assumptions about what is to be seen |
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35:23 | the world, expectations that seemed to in part from experience. So we |
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35:28 | certain experiences if I if I move hand close so you know it's going |
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35:33 | take up the whole screen. And off course because of the built in |
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35:41 | wiring for vision, very intricate, wiring system that exists revision very |
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35:51 | intricate circus from the retina to the cortex to further down the association |
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36:00 | And we do things. We already certain things. If we take this |
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36:04 | pattern and a it's a vigorous pattern biggest in the sense that you really |
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36:11 | tell if these circles are organized in or and columns. Now, if |
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36:25 | look in B, I would ask , what does this represent? Be |
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36:33 | top and you'll say, Well, blue rose. Five. It's |
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36:42 | yellow, blue, yellow, yellow roh. No, I think |
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36:47 | it's blue columns and yellow columns, columns, yellow columns, blue |
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36:55 | yellow columns. And if you look this image, my brain tells me |
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37:00 | yellow. Roast blue rose, yellow , blue row, yellow row, |
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37:06 | row. That's just a Nasaf option we make because of the similarity. |
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37:14 | group yellow together, we group blue , and if somebody went to ask |
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37:21 | , will say, Well, this columns and this is Rose. In |
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37:27 | , it may not be in It maybe rose off blue and |
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37:33 | blue and yellow, blue and But your brain, your visual organization |
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37:41 | the way that you're seeing these patterns based on this principles of similarity, |
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37:46 | grouping things together similar in color, principles. Proximity. If you looked |
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37:56 | the image here on the right, would say off course it zits columns |
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38:01 | dots. And if you looked on bottom here, you say it's rows |
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38:06 | dots. But that may not be case. We were doing that because |
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38:12 | we see it. And that's because the proximity so thes air closer to |
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38:19 | other, vertically and further away from other, horizontally. So we immediately |
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38:28 | , Well, there's got to be column. This these air all group |
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38:32 | together and proximity principle tells us this called. Likewise, here. Here |
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38:41 | distance is closer horizontally as opposed to e. So we say immediately, |
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38:47 | on this proximity encoding in a way , okay, these arose of blue |
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38:57 | . Of course, they have a of different delusions. This is just |
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39:03 | know this line that if you took these blue lines, who would think |
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39:08 | number two is longer because it has arrowheads that are outward versus the arrowheads |
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39:17 | go in. Likewise, as you , this is not an illusion. |
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39:23 | , you know, again that I become much bigger. I didn't become |
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39:27 | smaller and shrunk to three feeds because moved away. So we make certain |
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39:37 | . There's a lot of different illusions some of the once that were in |
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39:43 | . So it's the vase illusion. see a vase of people see two |
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39:47 | facing each other to noses here This is the one that it's not |
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39:53 | up very well, but it's a yellow on frogs and green, and |
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39:58 | other thing about the illusions. Once see them, you learn them. |
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40:02 | you can pick them up very Some of the complex illusions may take |
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40:06 | a few seconds to realize what you're at. But the next time you |
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40:11 | and you see that same image with same illusion, that will be less |
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40:15 | a second. Like I know I've seen this before. You |
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40:18 | we constructed in your brain much, faster. So what are we looking |
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40:23 | ? Where we're looking at these different we're looking at light on and |
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40:31 | which is electromagnetic radiation, which has wavelength, uh, frequency that will |
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40:41 | that wavelength and certain amplitude, which be the strength of that particular lighter |
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40:47 | you wanna call it luminous when you're light about how many lumens will be |
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40:52 | amplitude of how how how bright that can shine for example, within a |
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40:59 | wavelength. So our electromagnetic radiations that absorbed and perceived by our eyes fall |
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41:10 | the range of 400 to 700 This is the wavelength in nanometers, |
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41:19 | the visible light in the visible spectrum , orange, yellow, green, |
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41:28 | , indica violent. So the shortest violent and shorter than 400 nanometer |
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41:38 | our ultraviolet rays and even shorter than . Our X rays and even shorter |
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41:48 | wavelengths are gamma rights. So if look on the other spectrum on the |
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41:57 | , which is 700 nanometers longer wavelength is infrared race. Then you have |
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42:08 | race that are very long way length you have broadcast bad broadcast bands. |
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42:15 | you have a C circuits. So visible light range I'm sure you may |
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42:22 | from maybe chemistry in high school, G. Bev Roy G. Dev |
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42:32 | the longest Red, orange, yellow , the ivy he is. |
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42:40 | swell, gentlemen. Roy G. Roy Red, orange, yellow, |
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42:46 | , blue Indigo Violence can never forget Roy G did just have to remember |
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42:51 | Red Roy is the 700 nanometer read , and then you have in for |
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43:00 | . And if you think about I want the What is the |
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43:04 | You know, ultraviolet is on that . Okay, so the slide that |
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43:11 | the eye, what happens is a of light can get reflected, and |
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43:16 | does from different surfaces could be absorbed different surfaces that the surfaces light white |
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43:23 | will reflect a lot of line black will absorb more light. And |
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43:30 | once the light hands a different medium air to water, then you have |
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43:37 | bending the rays of light, which referred to as refraction. So that |
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43:45 | enters into the pupil. This is pupil right here, Eyeball. This |
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43:52 | your eye. This is the Irish the pupil on this Is this Clara |
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43:58 | the iris, and then you have extra ocular muscles. Here. You |
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44:05 | , the ocular muscles are ocular motor , ocular muscles, movement off the |
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44:14 | movement off the eye muscles. You the cornea here in front, |
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44:19 | And then in the back, you the retina and the optic nerve that |
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44:24 | out off the I. So once exits out of the I one more |
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44:30 | , that goes into the solemn this L g m and from Thala mus |
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44:34 | L g m. It gets sent the primary visual cortex in the occipital |
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44:44 | . Here you have your locker All glam that is going to generate |
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44:48 | tears. Um, canal for for drainage. Here again, the |
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44:53 | the irises. Claire surrounding it. is a side view oven eyeball, |
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44:59 | you may. It was cut through sagittal plane. And what you're seeing |
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45:06 | is you're seeing the cornea on the surface here. Okay, you're seeing |
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45:16 | you have the acquis humor which sits in front, off the iris and |
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45:26 | pupil. So there's this cushion here fluid that's sitting between the cornea and |
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45:38 | and the pupil and behind the which is essentially a little shudder that |
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45:47 | the enter into the light. And can close that shutter and make it |
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45:52 | , and you can open the shutter make it larger. Okay, so |
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45:57 | is what, the pupil, the , And then you have the lens |
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46:02 | , and this lands okay, can thicker or sinner. So this Lance |
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46:12 | suspended and it's held up by the Serie Ligaments coming from Silla. Everybody |
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46:24 | and these suspensive ligaments can stretch. , we can contract and they can |
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46:34 | the lands or they can relax and can bulk up the lens. So |
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46:41 | they contract, the lens will get . And if they relax, the |
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46:47 | will get thicker. And as the gets thinner and thicker, it allows |
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46:53 | the light that comes into the Pew to precisely focus that image precisely on |
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47:01 | retina, which is located in the back off the eyeball have all is |
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47:08 | with the vitreous humor. It's gel liquid substance that gives an eyeball |
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47:17 | keeps up a certain shape off the , and you have the retina in |
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47:24 | back way. Have the muscle. the moving the eyeball on the movement |
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47:31 | the eyeball will move the eyeball, for the eyeball thio look at a |
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47:38 | area in the field of view and for the people Thio let in more |
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47:44 | less light and then for the lens become thinner or thicker as its |
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47:51 | The incoming light directing it on to retina phobia is where you have the |
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47:58 | resolution vision, and it is located in the path of the pupil directly |
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48:05 | the direct rays of light will be and hitting phobia, which is in |
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48:10 | back part of the retina with the resolution photo receptors or the highest special |
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48:19 | . And on the back off the you have optic nerve. So the |
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48:25 | where optic nerve exits out of the is called the optic disc, and |
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48:30 | optic disc is where you would have blind spot because there's no right in |
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48:35 | here in one area where all of output from the retina and the out |
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48:40 | in the eyeball exits out there is object in Europe, and obviously the |
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48:46 | has little blood vessels and micro vessels are innovating the eyeball. And sometimes |
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48:54 | may even see it. If somebody's tired or they may have an inflammation |
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49:01 | or they're running the I two you may see a pop. |
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49:04 | That's all that might be temporarily. you could observe it with with your |
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49:11 | eye as well this little blood Okay, okay, So more and |
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49:18 | and more and more about this is intricate anatomy of the eyeball on the |
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49:23 | of the life, passing indirectly again so that it gets directly on. |
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49:29 | phobia, which has the highest resolution requires the highest amount of light. |
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49:34 | it's both they need each other. needs to hit phobia. Thio, |
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49:42 | us to see the detail in the and phobia needs to be located. |
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49:47 | most lied to come in in order resolve that detail in the world, |
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49:54 | right now has a very specific And in the way, what is |
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50:00 | here is that if you're fixating in point of space, let's say you're |
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50:04 | at a cam and space right. fixating room, this camp and that |
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50:12 | . Looking at the Cannes, let's , in a certain way, your |
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50:16 | , lightest coming in, that's going the phobia and notice What you have |
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50:21 | a polite will. Pass through the through the hole, eyeball the whole |
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50:30 | here through the whole vitreous humor solution it hits the back of the eyeball |
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50:38 | retina, and you have three Three major types of cells here, |
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50:46 | by Poland photo receptor cells and photo cells and actually true, introduce delight |
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50:54 | a photon of light or electromagnetic signal electrochemical signal. They're located in the |
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51:05 | back of the threat middle circuit. it, you have the pigment feeling |
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51:13 | right, so retina is part of central nervous system. Phobia is again |
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51:20 | highest acuity, the highest resolution And most of the time, if |
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51:25 | want to look at something in great , we'll move our eyes around and |
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51:30 | our lenses and focus our vision onto particular object, uh, to resolve |
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51:37 | in great detail, Um, with . So let's look briefly at this |
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51:45 | . There's gonna be more and more as we look into the visual |
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51:50 | the retina, and move up into l G m. But for today |
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51:56 | will learn that again. This visual coming in, which is the direction |
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52:01 | life, will pass through this jungle the cells and synopsis interconnected synopsis and |
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52:08 | gonna then finally hit the photo And you have two types of major |
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52:15 | of types of photos. Separate. rod photo receptors that air a |
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52:20 | We do not process color, and have chromatic cone photoreceptors that's specifically designed |
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52:28 | process blue, red or green color activation of red, blue and green |
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52:35 | various combinations will create a variety of of the visual world on the colors |
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52:41 | you're seeing, and it's quite Toe learn the chickens, chicken. |
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52:46 | actually see a lot more Hughes in world that we can see. Can |
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52:52 | imagine if you have the ability to , like 2000 Hughes versus like some |
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52:57 | 100 years that we can see so world is actually the very colorful. |
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53:05 | think about it next time you go Chick fil A, Uh, |
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53:10 | that's a joke. But we do these chromatic, uh, cones. |
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53:16 | that's how activation of different level of , blue and green can give us |
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53:21 | variations and combinations of Hughes and colors we're seeing now that information is actually |
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53:27 | process and photoreceptors and gets communicated to Selves, bipolar cells and send their |
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53:36 | and contact ganglion cells. In they're referred to as either ganglion cells |
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53:42 | retinal ganglion cells because they form a . Off optic nerve fibers exits out |
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53:53 | they go from Ratna into the lateral Nicolas nucleus. So that's why they're |
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54:00 | retina Jinich, Oculus self. They from retina and the optic nerve. |
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54:07 | axles goes into the following us into lateral technical opponents of the followers. |
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54:14 | this is, if you may, kind of ah communication happening from photo |
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54:21 | , bipolar cells and then to the cells that send information through the optic |
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54:26 | into the lateral Jamaica nucleus and the between the horizontal on bipolar cells. |
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54:33 | synaptic transmission is being checked and controlled modulated by south and a cold horizontal |
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54:40 | . And the communication between bipolar south the ganglion cells is being modulated and |
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54:48 | by a McQueen cells. And we learn about the circuitry and greater detail |
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54:54 | these, uh, horizontal and immigrants control on bipolar self communication of that |
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55:01 | as well. Okay, so I for the sake of time, this |
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55:08 | again quite a bit of information that covered today I am going Thio end |
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55:16 | lecture here today and we'll pick up we left off at the next |
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55:26 | So I will check the chat to sure that I can answer all of |
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55:31 | questions and I will see you again |
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