© Distribution of this video is restricted by its owner
00:00 | This is the continuation off this Sensory system lecture we left off talking |
|
|
00:07 | Dermot. Tom's herpes zoster virus can chicken pox how the virus can remain |
|
|
00:17 | and then can reappear in one in . One dorsal root ganglion on one |
|
|
00:26 | highlighting one of the Dermot owns, are essentially the projections, Um, |
|
|
00:34 | you can see outline here on the and each one of these areas outlined |
|
|
00:42 | corresponds Teoh, a single spinal nerve to either the left or the right |
|
|
00:48 | of that nerve. Okay, so when we studied the visual system, |
|
|
00:55 | looked at the visual projections and the projections came from the retina into thalamus |
|
|
01:04 | into the primary visual cortex. When looked at the auditory system, the |
|
|
01:11 | projections where from the here, right the cochlea spiral ganglion South CO klia |
|
|
01:25 | superior, olive in fear. Ical ous in the brains town mediagenic alert |
|
|
01:34 | of the columns and the primary auditory . So you should be able to |
|
|
01:38 | these visual projections and pathways and auditory and pathways. So when we talk |
|
|
01:47 | the sensory neurons and the C N , we have Thio realize that there |
|
|
01:58 | certain fiber since a matter sensor information we discussed early on that is more |
|
|
02:08 | in nature. So we talked about reflex arch, and we talked about |
|
|
02:15 | just an activation of, ah sensory and one motor output can cause a |
|
|
02:22 | of a muscle. And then anything happens at the level of the spinal |
|
|
02:29 | , especially if anything moves, will inform through this ascending dorsal call on |
|
|
02:37 | through these ascending pathways will inform the water processing centers all the way. |
|
|
02:43 | was a matter sensory cortex. So some ways, you may think that |
|
|
02:50 | what happens at the level of the cord and even what may happen at |
|
|
02:54 | level of the brain stem, in ways it's somewhat reflexive is things that |
|
|
03:01 | don't think about much when I say at the level of the brain |
|
|
03:08 | I mean the psychotic eye movement, superior curricula sauce, the processing off |
|
|
03:14 | information and inferior calculus. Is there of the very rudimentary information processing is |
|
|
03:21 | When, uh, we talk about , we're talking also about the breathing |
|
|
03:29 | , the vital body centers that we think about the activity of how often |
|
|
03:35 | breathe or how fast our heart rate , uh, beating until there's something |
|
|
03:42 | . And, uh, these air controls that are seamless at the level |
|
|
03:47 | the spinal cord. They're more or reflexive. But if it reaches any |
|
|
03:51 | the higher processing centers in the thalamus in the cortex, then you can |
|
|
03:57 | of these areas becoming conscious, so speak, projections because now it gets |
|
|
04:04 | consciously the neocortex and gets bound with sensory inputs that might be simultaneous with |
|
|
04:13 | matter. Sensory inputs. And at the level of the spinal |
|
|
04:18 | these projections from the spinal cord will up. It's still laterally through the |
|
|
04:24 | column until it we just the dorsal nuclei here at Cut number two, |
|
|
04:30 | is through the doula blah anggada. this is it's the lateral information until |
|
|
04:37 | reaches medulla blonde gotta And from there have information that crosses over control |
|
|
04:44 | So if you recall now the nucleus the solemn asses ventral posterior eventual posterior |
|
|
04:52 | nucleus. This is the VP stands venture posterior nucleus of the Palomas. |
|
|
04:58 | where this amount of sensor connections air in and from the thalamus again. |
|
|
05:04 | of the sensor information goes in the and remember, visual information goes through |
|
|
05:10 | lot. Algae, Nicollet, nucleus information through media lja Nicollet nucleus spinal |
|
|
05:16 | matter sensor information from ventral posterior nucleus the thalamus From the following list These |
|
|
05:23 | going to their respective primary cornices Primary cortex, primary auditory cortex. In |
|
|
05:28 | case, it goes into the So matter sensory cortex area s one |
|
|
05:35 | in the parietal low. Uh, close to the primary motor area, |
|
|
05:42 | you recall. Okay, So two things is that if you go to |
|
|
05:50 | school or if you go into any therapy where you study spinal cord injury |
|
|
05:56 | recovery from spinal cord injury, you'll that damage to the fibers up Thio |
|
|
06:05 | blonde gotta will remain on the insta side. But damage above will obviously |
|
|
06:13 | be contra lateral origin. Uh, know, on the other hand, |
|
|
06:21 | that comes from brain stem in the and the head is processed by trigeminal |
|
|
06:30 | . Five. If you remember, is trigeminal nerve, which is cranial |
|
|
06:37 | five And these a large mechanical receptors phase. And if you recall this |
|
|
06:44 | both sensory motor. So the same through cranial nerve, you will have |
|
|
06:50 | sensor information that goes up to the somatic sensory cortex. Again, it |
|
|
06:56 | over here at the level that the one okay, through the principal sensory |
|
|
07:03 | nucleus here crosses over projects into the posterior nucleus of the columnist and from |
|
|
07:11 | into the somatic sensory primary somatic sensory . So all of the information below |
|
|
07:18 | neck from the spinal cord basically crosses at the level of medulla goes to |
|
|
07:27 | , goes to the primary sensor All of the information above the neck |
|
|
07:33 | in the face is processed by cranial . Five trigeminal nerve, five fibers |
|
|
07:39 | carry that cross over that information. I'm carrying through the eventual posterior nucleus |
|
|
07:44 | the primary somatic sensory cortex. So we talk about maps and we talked |
|
|
07:53 | maps and the visual cortex, and we talk about cortical maps or representations |
|
|
08:01 | , what we see is the outside reflected in the anatomical structuring off the |
|
|
08:09 | . Well, we talk about We talk about ocular dominance columns, |
|
|
08:14 | example. So you remember that in primary visual cortex that was ocular dominance |
|
|
08:20 | . There's a columns that were dominated either the left or the right |
|
|
08:26 | So when we look in the primary sensory cortex, of course you will |
|
|
08:32 | the overall structure off homunculus reflected in primaries amount of sensor cortex that will |
|
|
08:42 | similar. Thio this individual. So will be an actual cortical map, |
|
|
08:48 | , represented in the primary sensory cortex the body of all of the somatic |
|
|
08:56 | . So it's a matter. Sensory receives dance input from dental posterior |
|
|
09:02 | which is in the following months. neurons in this matter sensor cortex |
|
|
09:08 | Remember, this is a central sulcus separates a front of love from the |
|
|
09:13 | lobe and then the other side of central focus. In the frontal |
|
|
09:18 | you will have the primary motor and here in the parietal lobe, |
|
|
09:25 | have some matter. Sensory cortex area primary, somatic sensory cortex. And |
|
|
09:30 | like with the one visual cortex one two, you have some matter. |
|
|
09:35 | s one s two s, three tertiary, and so on until reaches |
|
|
09:41 | 57 in it again reaches association areas this amount of sensor information is blended |
|
|
09:48 | information from other sensory modality, such vision, hearing and other cortical processing |
|
|
09:57 | such as emotions and logic and and such legions in this region. |
|
|
10:04 | if you legion somatic sensory cortex, there's a damage sense of somatic sensory |
|
|
10:10 | in Paris, somatic sensations. So you have a lesion to some matter |
|
|
10:14 | cortex, you may not have somatic . You may have impaired somatic |
|
|
10:20 | or they could be even sometimes Uh, but it could be |
|
|
10:27 | A loss of function on it could exaggerated function, depending on the amount |
|
|
10:34 | damage and the specificity, anatomical specificity that damage. So if you were |
|
|
10:40 | , electrical stimulates a matter sensor Cortex simulation amongst the matter Sensor Experience If |
|
|
10:50 | were to stimulate the matter of sensor , you would not produce movement if |
|
|
10:56 | were to stimulate the primary motor That's the motor commands. You will |
|
|
11:02 | seeing movement, but the body. you stimulate the neurons and somatic |
|
|
11:07 | you feel somatic sensations. You would the feeling off body sensations. So |
|
|
11:15 | in any, you know, cortical . And this amount of sensory cortex |
|
|
11:20 | also have a columnar, an alarm structure. It has a six layers |
|
|
11:28 | we know it, and it has column structure. But this column |
|
|
11:35 | interestingly, is dedicated in this case the anatomical parts of your body. |
|
|
11:43 | in this example, we're looking at map of your fingers. So if |
|
|
11:48 | were to look in this primary amount sense of context, that was actually |
|
|
11:53 | to be an architectural er, then the map that represents digit one digit |
|
|
12:00 | Digit three and you will have slowly neurons, these pink collars interspersed with |
|
|
12:07 | adapting neurons. Remember, we talked slowly adapting, uh, nerve |
|
|
12:16 | sensory nerve endings and slowly and rapidly one. So at the level off |
|
|
12:24 | map for fingers in the neocortex, also have slowly and rapidly, adapting |
|
|
12:31 | accordingly. And you have projections for that that form the slow and rapidly |
|
|
12:37 | neuron columns for each finger. But fingers and digit 123 is, |
|
|
12:49 | course, not the only thing that's this so matter topic nap, individual |
|
|
12:56 | . We have a red new topic point by point representation of the outside |
|
|
13:01 | if we're seeing that point by point of preserved installments in the primary visual |
|
|
13:08 | auditory. We have a tono topic . The map of tones and that |
|
|
13:13 | from the cochlea is reflected all the in the primary auditory cortex. |
|
|
13:19 | in somatic sensory system, we have so matter topic or so matter |
|
|
13:23 | Now this map that you've seen here basically body parts that are laid out |
|
|
13:30 | stretched out here over the salsa and gyre I that represent the primary somatic |
|
|
13:38 | cortex. And what you're seeing here this homunculus, which we call, |
|
|
13:45 | is the map, this exaggerated map the human body and it's exaggerated because |
|
|
13:52 | not scaled to human bodies. It's it's a caricature of the human |
|
|
13:58 | and this caricature is representative of the of cortical space that is dedicated to |
|
|
14:06 | parts of the human body. There's features of the Semana topic map. |
|
|
14:12 | map is not continues. It's not . When you think about the relationship |
|
|
14:18 | the anatomy of the body, for , do you think that your index |
|
|
14:27 | is anatomically very close? Thio your well, but it is not. |
|
|
14:34 | actually quite far away, and I say that that that maybe my shoulder |
|
|
14:40 | be closer to my forehead, But on this map, it's just |
|
|
14:45 | , and it's a finger. It's to the forehead. Yeah, maybe |
|
|
14:50 | association of how busy those areas are how those these areas interacting with other |
|
|
14:56 | that are most common for us to and feel sensations from face and hands |
|
|
15:02 | feed ourselves and listen on the phones things like that to form these maps |
|
|
15:07 | that over the evolution of the human . Also, you know, the |
|
|
15:13 | also typically not located by the Eso This is another discontinuity, in |
|
|
15:20 | way, in this caricature off the . But it is quite obvious from |
|
|
15:26 | caricature and from the layout here, body parts are important. How much |
|
|
15:35 | is dedicated to mouth, so more dedicated to lips and mouth than to |
|
|
15:42 | entire trunk off the body. But entire trunk of the body is much |
|
|
15:48 | , then the face of the But that doesn't matter. It's the |
|
|
15:52 | sensations. It's the importance of certain parts. Certain body parts, arm |
|
|
15:59 | important. Your hands are more Your lips, your nose, your |
|
|
16:05 | , your generals, they're Mawr important your everyday living, for your somatic |
|
|
16:14 | , for arousal of Samadi sensations for yourselves and adapting to this environment. |
|
|
16:25 | , so this is the map that would see this mom uncle asses the |
|
|
16:29 | that you would see if you were look in the more primitive animals. |
|
|
16:36 | in this case, let's look at rodents. You have a map. |
|
|
16:43 | a matter of topic map and But what do rodents do most of |
|
|
16:48 | time and how do they survive? have huge olfactory involves. They smell |
|
|
16:55 | and the whisk around This is a sensation. So if you look at |
|
|
17:01 | Retton Oculus, this is not the Oculus, but this is the right |
|
|
17:05 | rats, Oculus or mouse Oculus. , this is the map of the |
|
|
17:12 | or the mouth of the right of mouse or right, or any rodent |
|
|
17:17 | you can see the square here. square represents the the breast, |
|
|
17:26 | and the follicles, The whisker pad the rodents here. Okay, so |
|
|
17:34 | huge amount of medicines or cortex and is dedicated to this whisking the gristle |
|
|
17:43 | here for some matter since. Or . This is how these animals sense |
|
|
17:49 | outside world. Okay, we don't that. We use our hands. |
|
|
17:54 | don't have whiskers. We have facial , but we don't use it for |
|
|
18:00 | the world around. Although, uh, it could be at some |
|
|
18:05 | if you grow it really long. But in any case, on this |
|
|
18:11 | Brisa on this whisker pads, you a certain organization off the follicles you |
|
|
18:19 | 12345 hair follicles. Here you have five rows of hair follicles, and |
|
|
18:29 | row has a certain number of hair . And this is remarkable that when |
|
|
18:35 | look and the somatic sensory cortex off rodent animals and you do a |
|
|
18:44 | would you reveal you reveal in the amount of sensory cortex, a structure |
|
|
18:51 | we call a barrel cortex. It's barrel like appearances of these round shape |
|
|
18:58 | areas. And so we call it barrel cortex and This is the cartoon |
|
|
19:05 | of that barrel cortex. And guess ? Just like you have. 52345 |
|
|
19:12 | of whiskers. You have exact same 12345 rows of these barrels and each |
|
|
19:24 | of these barrels. One of these and somatic sensory cortex is the |
|
|
19:31 | There's a critical map is a cortical and architectural map that represents a single |
|
|
19:38 | on a whisker pad in this And these maps can change so you |
|
|
19:50 | do several very interesting experiments. You first of all, stimulate and move |
|
|
19:56 | hair follicle, and you can look the anatomy and you could look at |
|
|
20:00 | anatomy if you have increased activity on air follicle. And look at this |
|
|
20:06 | coming from the whisker going into the going through the trigeminal ganglion, |
|
|
20:15 | going into the eventually into some other cortex. So now we're looking at |
|
|
20:21 | map here. Now we can manipulate off these whiskers and see whether we |
|
|
20:27 | change the map in the primaries amount sensory cortex. We can see what |
|
|
20:33 | if we do something different to this whisker in Rosie How does the map |
|
|
20:44 | on DSO? What you have, example, is do you have a |
|
|
20:52 | that is very active in this When you activate, you can also |
|
|
20:58 | brain activity. So this is the of brain activity saying that when you |
|
|
21:05 | right, see to whisker stimulus C whisker stimulus. You evoke this map |
|
|
21:10 | activity at the level of the primaries of sensory cortex. When you stimulate |
|
|
21:17 | to whisker stimulus, you vote a map, you activate different barrel cortex |
|
|
21:23 | you invoke over time. First of , this is the barrel cortex |
|
|
21:28 | a 10 milliseconds for C two This is the dog for E two |
|
|
21:34 | in different regions and then subsequently over , the stimulation of C two or |
|
|
21:39 | two whiskers developed these different looking so sensory maps. That air then obviously |
|
|
21:45 | with other activity in the brain. guess what happens if you inactivate c |
|
|
21:53 | whisker and you can inactivate that C whisker by locking it up mechanical, |
|
|
21:58 | you can actually eliminate it or cut off You actually then, without |
|
|
22:04 | you don't see a sea to map with E to activation. You can |
|
|
22:10 | enacted a C two whisker with chemical so you can block activity from that |
|
|
22:17 | two whisker locally with chemical injection. this case, we're injecting Sea and |
|
|
22:22 | X and the A P V. what C. N Q X and |
|
|
22:26 | P V stand for the glutamate receptor so you can inhibit glutamate receptor at |
|
|
22:33 | level of the whisker. And then can stimulate the whisker because it's |
|
|
22:38 | You will not see that map of . It's not translating into the |
|
|
22:43 | but the E two whisker, which not been affected. You will still |
|
|
22:47 | the map. So now you can the level off experimental manipulation you can |
|
|
22:52 | with this beautiful system, where you manipulate individual whisker individual whisk activity, |
|
|
22:58 | inhibit activity and individual whisker, and can see how it effects activity. |
|
|
23:06 | of activity in the brain war, restructuring of this activity, just like |
|
|
23:11 | saw in the visual cortex over And so this is the experiment in |
|
|
23:18 | you have a monkey and you have 12345 This is the map. It's |
|
|
23:25 | matter of sensory cortex. That represents digits. Okay, guess what |
|
|
23:32 | Uh, this animal who can lose digit three. It lost the middle |
|
|
23:39 | . Maybe was showing the middle finger lost the middle finger. Let's go |
|
|
23:44 | and see what happens in this Now, you can clearly see that |
|
|
23:49 | finger map dedicated to D four digit in digit to have expanded and have |
|
|
23:56 | over the map that was dedicated to three mhm. And this is not |
|
|
24:04 | not necessarily have to deal with the of the finger. Here is a |
|
|
24:09 | off these fingers here and continuous stimulation digit to and digit three in largest |
|
|
24:16 | matter sensor cortex, the map that dedicated to digit to and digit |
|
|
24:21 | So now think about your own. matter of sensory cortex, your |
|
|
24:25 | revolution, how they change and how change the finger movement. What are |
|
|
24:30 | most used fingers in your hand? realize how these maps are not |
|
|
24:36 | They're not standing in the sense of or even side of architectural. So |
|
|
24:42 | end this material here today. I you good luck on the quiz and |
|
|
24:48 | will see you next week because it's Week and we will not have a |
|
|
24:55 | lecture after you take the quiz. you so much and good |
|