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00:01 Fun. So this is lecture 19 the science. And we're talking about

00:07 data sensory system and what you see the right uh upper corner is a

00:15 . It's called the homunculus. Uh we'll talk about that in a

00:19 Maybe it's a little bit too dark one, but this may make him

00:23 off. So, somatosensory system is sensations and we're talking about somatic

00:31 anything that touches your body, the , pain, irritation, mosquito bites

00:40 everything below the head down. The system was processed through spinal cord,

00:48 root ganglia cells in the spinal Everything that is a matter of sensory

00:54 here around your face and head. you're talking about the sensory components of

01:04 of the cochlea nerves, uh uh of the cranial nerves and in particular

01:08 nerves like triamino nerve. Ok. what a thematic sensation, stimuli,

01:15 , position of joints and muscles. also called proprioception, distension of

01:22 temperature of limbs and brain here. receptor, somatosensory receptors are unique in

01:29 sense that they are distributed throughout the . When we talked about photoreceptors that

01:35 located in the retinas. When we about hair cells, the auditory receptor

01:41 , they were in the cochlea somatosensory cells. The nerve endings are located

01:50 the body and the head. The important four senses that it's processing is

01:56 , temperature, pain, and proprioception is the largest organ in your

02:05 And you have a hairy skin and glamorous skin. And uh it's always

02:12 to remind ourselves how much money we on our skin. It's probably also

02:18 most expensive organ because shampoos creams, , deodorants, we spend a lot

02:28 money, you know, laser hair , whatever it may be. Uh

02:34 this is an important organ. You survive without the skin and people lose

02:40 areas of the skin, for due to burns, you cannot

02:45 it's a protective uh layer and it us to, to live and it

02:52 the nerve ending, different nerve the markle discs. For example,

02:57 my core puzzles, the three nerve that are coming out. All of

03:03 are part of the sensory component of spinal nerve, which essentially becomes the

03:12 root ganglia component that carries the a into the spinal cord that will be

03:19 the MC ad. By the way and things like that, then you

03:24 hair follicle that's wrapped around with the follicle receptors and you have a chi

03:30 core puzzle Ruini nerve endings. So is a variety of different sensory nerve

03:39 that are present in different parts of skin. And in particular, as

03:45 can see, this is the epidermis most of what we're talking about is

03:51 in the dermis area. OK. receptive fields. Remember receptive fields in

04:00 retina, we said that in the receptive fields or these centers around.

04:05 that's because the retinal cells, the will react mostly to these round center

04:13 illuminations. That's when the retinal ganglion in the retina will produce action

04:19 So the same way here now that familiar with that concept in, in

04:24 way in a more complex manner. , we can understand this receptive field

04:31 in a very simple manner. This field is where I touched, there's

04:36 to be nerve endings, they are to process information from this area versus

04:42 area versus this area. And that the receptive field. This is the

04:47 field. Now, the sizes of receptive fields, they vary across the

04:53 and there are some areas where receptive are much smaller and those are typically

04:58 most sensitive or the most dexterous and important parts for handling different things and

05:06 and feeling different things. So there's uh two point discrimination fast and the

05:15 point discrimination test is that you can two uh pans, for example,

05:21 are equivalent and place them very close . And if you place these,

05:25 , this is not a good example if, let's say, imagine these

05:29 too small. So I place them my hand and I can clearly tell

05:33 there are 22 endings that are stimulating hand. And that's because the nerve

05:40 here and the receptive fields are, small and they can discriminate that there

05:45 actually two if I touch here and didn't know I'm holding two and somebody

05:52 was doing that in this area except field sizes are very large, 42

06:01 , right? 25 millimeters, 42 . That's a lot 10 millimeters is

06:09 centimeter 4.5 centimeters here almost. So talking about an inch and a half

06:15 size. So that means that the between these have to be at least

06:19 inch and a half from my torso tell. Yes, there are two

06:23 that are distinct. And if I them close together, I can no

06:27 tell that because the receptive fields are large and it keeps falling within the

06:31 receptive field. So index fingers will the smallest receptive fields because we typically

06:40 it and we use it a lot with the digital devices too, thumbs

06:44 pretty small receptive fields. Hands in forearm, not so much, there's

06:50 that much discrimination and the receptive fields the forearm, face lifts. Of

06:56 , a lot of very sensitive areas for a number of reasons will have

07:02 , the discrimination uh ability, big , still pretty small receptive feel with

07:09 and calf. Again. Like if put two objects and touch yourself,

07:13 cannot tell if it's two or unless you spread them far enough

07:17 And then you can tell that it's two. So why use fingertips for

07:22 reading? Because you have high densities the receptors and you can see the

07:29 receptors because of their sizes. Mesner puzzles will have these really tiny receptive

07:36 . But as you can see, in the previous picture, a lot

07:40 them were intermingled together. So where have Mesner core puzzles, you may

07:46 have a little bit of overlapping For example, with the Petrini core

07:53 , receptive field and Putin core puzzles much larger nerve endings and therefore their

07:59 fields are much larger. But when get to, again to the

08:04 you have a lot of small nerve with very small receptive fields allowing you

08:12 discriminate very small differences. And that's people that are blind or visually challenged

08:20 use braille to read. And that's done with the fingertips and typically

08:25 the index fingers and maybe pubs and fingers. So small receptive fields.

08:32 reason why is the areas that we a lot that have high sensitivity,

08:40 more of the brain area to process information. So you'll see that and

08:47 why the caricature of homunculus was a of that. So this is just

08:52 illustration, an illustration of how you stimulate and you can record action potentials

09:00 uh this nerve, the median nerve this case. And these are the

09:07 main receptive uh uh nerve nerve Mesner Paum Marco and Rois, some

09:18 them are small. Myers and Merkel small. Some of them have large

09:24 field sizes and ruin. That distinction them is not just in size and

09:32 much of it would contribute to the discrimination on the stimulus. But also

09:36 of them are rapidly adapting and others slow adapting. So my and Virginia

09:44 and large ones are rapidly adapting and mark and the are slow in that

09:51 . And as you can see it is an example of somebody something

09:55 the skin like you put a shirt and you generate a number of action

10:01 in this nerve, right? You that, but score muscles after you

10:07 a shirt on no longer, you're longer feeling that shirt, there's no

10:12 of the same stimulus as the initial . And then of course, if

10:16 now lift the shirt, you will see some action potentials here at the

10:21 of the stimulus and at the end the stimulus and they're very rapidly

10:25 That means that they fire action potentials they adapt to the stimulus and they

10:31 firing the actual, that's what this adaptation is to the stimulus. It's

10:36 . Right. Because you don't want do your clothing all day long or

10:39 shoes or your socks. And of , if it's uncomfortable or too tight

10:43 something, you will keep adjusting it of the time. But in

10:47 even then you'll kind of forget about for most of the day.

10:51 the slow ones, you can see the stimulant begins, there's a lot

10:54 action potential. So it kind it persists and there's a reason for

10:59 too because some of the stimuli, example, like pain or vision and

11:02 need to have persistent reminder that there's there like a mosquito bite, for

11:08 . OK. But you can see they're adapting but they're slowly adapting and

11:13 continuing very low rates of firing throughout continuous stimulus. Uh the more girls

11:22 discs and the endings, OK. the primary afferent in the central nervous

11:30 , again, that afference is the information in this case. Yes.

11:45 so the largest star probably in the and the back here and 42

11:53 So you're looking at an inch and half to almost two inches in

11:58 Yeah, that's why you would need , if you wanted to feel too

12:03 here on the torso, on the , you would have to separate them

12:08 than two inches apart. Let's say you don't, it's gonna appear to

12:14 if you closed your eyes it's gonna to you as a single stimulus.

12:18 if you spread it apart, I can clearly tell it's too because

12:23 receptive field sizes are very large in parts of the body, but not

12:30 others. And that's why we use for brain reading where they're really small

12:34 sensitive. So the apparent information is sensor information that's traveling. In this

12:41 , a famous spinal cord coming into dorsal side of the spinal cord part

12:46 the dorsal root Galin component contains the here. Remember the pseudo unipolar cells

12:52 have the peripheral axons and those peripheral will contain the nerve ending and then

12:58 central axons that will innervate and process that inflammation into the dorsal horn of

13:06 spinal cord which will contact the motor and the inter neurons. And then

13:10 motor component will come out venally, the motor nerve. And that is

13:15 neuromuscular junction that we discuss in the of the skeletal muscles. In this

13:21 that we're discussing. And there are ather that carry that information and they

13:28 in size from the largest one one uh about 13 to 20 micrometers

13:38 diameter. And they're myelinated to the ones, group, one,

13:45 two, group three, group group group three, the smallest ones

13:51 1 to 5 millimeters in diameter and still myelinated. And then there's group

13:57 , there are 0.2 to one 0.5 , the smallest diameter axons,

14:05 Because we're talking about axons, myelinated , but they're amongst those are unmyelinated

14:11 also within that a fiber module. . Now, the larger fibers and

14:20 better insulated or insulated larger fibers will the fastest ones because they'll conduct information

14:27 the fastest way. The smaller the there are and there is less

14:33 the speed of that conductance drops significantly thus different groups of apparent fibers are

14:44 for slightly different SOMA sensor information processing group one is appropriate exception of skeletal

14:55 location of your muscles and joints with to your body and gravity. Appropriate

15:03 group two, the kind of of skin group, three pain and temperature

15:12 group four, the slowest is temperature and itch information processing. So let's

15:21 of an analogy of you have a which is your hand and you're gonna

15:29 it in an ice bucket, it's bucket full of iced water, not

15:35 ice, ice water. Yeah. first thing is you're moving your hand

15:42 this is proprioception. This is the of your hand with respect to the

15:46 water. Second thing is you touch water, right? Second sensation.

15:55 first is the location. Second is sensation, mechanical receptors, different

16:02 First, you understand that now you're in air, you're in water and

16:05 also feel hard ice cubes against your . Ok. So these are mechanoreceptor

16:14 . Well, before pain. Usually temperature. Then after you put it

16:20 a few milliseconds, 10 2030 you'll , oh, it's cold water.

16:28 the temperature. Now, if you your hand long enough in that ice

16:34 full of ice water, you will feeling pain and that's gonna be the

16:41 perception and the pain and itch is , an equivalent of a mosquito

16:47 So first it's like, oh my where it is mosquito landed, I

16:52 it, it bit me. Then some time I feel pain and then

16:58 a while the itch persists. I , the mosquito is no longer

17:02 I may not even have pain but itch is persistent. So,

17:06 Um so uh primary for someone who sure they don't. Oh, that's

17:20 , that's a little bit different actually uh they will conduct the information for

17:27 . But pain processing will be taking in the spinal cord and in the

17:32 centers. So why they don't feel is because typically of the chemical changes

17:41 neural transmission and the perception of pain tolerance of pain. And in

17:46 one of the systems that controls pain the endocannabinoid system. And if a

17:53 has higher level of endo cannabinoids natural their bodies, they typically have higher

17:59 to pain too. Their perception of is not the same and so on

18:05 spinal cord, you will also chemical p typically that is involved in,

18:10 pain perception, processing and sending that for us to consciously perceive it.

18:19 , is there any like difference like the pain and to the,

18:29 three, between three and four, some overlap in the function.

18:36 But I hope that there's the difference temperature and pain, the pain.

18:44 . Yeah. The two, the both of these will process pain

18:47 temperature but they'll process it at different too. And the slowest one will

18:52 be responsible for the longest linger and sensation, which is typically itch or

18:58 of the skin like that because I to learn more if you know the

19:12 uh even slower conductance, even slower . Yeah, I mean, it

19:19 be nice if we had one fiber everything. But it, it goes

19:24 to the common theme of parallel redundance in processing. Let's say you

19:31 uh myelination in the periphery. That mean you're gonna lose all of the

19:36 because if you, you know, a myelinated fibers, you'll still be

19:41 to process certain information with the ones never had myelin the same.

19:48 OK. So spinal cord and we already talked about the segmentation of

19:55 spinal cord and we talked about the of the vertebra, cervical eric lumber

20:03 . And we talked about the nerves come in between cervical nerves and the

20:13 lumber five nerves here that are exiting the exiting out as motor neurons or

20:22 entering in as a and neurons in different areas. So the area,

20:31 example, from your hand here, information from your hand is processed at

20:40 C four, C five, C C four at the level of the

20:45 here. So for example, if have a pain in your hand all

20:51 way to here, it could be a number of reasons, carpal

20:56 which is here, you know, hit yourself in the hand, it

21:00 . But it also could be because using cell phone for too long in

21:04 screen position. And you're like, is my finger hurting? And that's

21:08 it's called the digital neck, you , so it's really like it,

21:13 , it moves and we stay in position for how many hours sometimes if

21:19 watching a movie on the small screen something like that, really, you

21:23 displaced your neck at this area C three C four C five forward

21:30 it can become problematic over a number years. So now, Sarel nerves

21:37 process all of the information from lower in the back, lumber, low

21:44 in the front. The is the essentially and the back here. And

21:51 is cervical all the way here to one and C two in the back

21:57 the, of the head. So are referred as Dermo toes where on

22:06 side, let's say C three the that is on A for C three

22:15 carry all of that information on this and enter that information into the dorsal

22:23 on one side. And then the side of the nerve will carry information

22:28 the opposite side. So in each , you have two dermas one ride

22:34 , let's say for C three, love dermato, C three, L

22:41 , L two, Dermato here on right and L two Dermato or L

22:46 Dermato on the left. Ok. it's a single spinal segment, not

22:54 across the whole body. Derma Uh You will see before COVID-19 came

23:03 . Uh the pharmacies have big signs vaccinations for shingles. So let's talk

23:10 this excerpt from your book. It's shingles and dermato. Uh The

23:17 most of us were infected by the Oster virus, commonly known as chickenpox

23:23 a week are so covered with red spots on our skin. We usually

23:30 out of sight is not out of of body. However, the virus

23:34 in our primary sensory neurons dormant but . So most people never hear from

23:41 again. But in some cases, it's now becoming uh if you're 50

23:47 over, it's about one in 51 four. So if you had uh

23:55 aster infection and you had chickenpox as child, then you have one in

24:02 chance of actually developing a condition that called shingles. So the virus sits

24:12 . So after the spots go away you're no longer have chicken pox,

24:18 virus actually goes back from the face from the upper body here and sits

24:28 and it sits dormant and the dorsal gang and then, well, whatever

24:36 reason, we don't know why, and five, why this one person

24:40 different from that of four and five didn't have the shingles. But this

24:46 reactivates. It typically reactivates in just single dermato on one side of the

24:53 . So this is person's lower back . And you can see that this

24:57 kind of a like nature's way of this dermato. It's almost a confirmation

25:03 this is the dermato. It would processed probably by uh lumbar lower lumbar

25:09 upper Sarel uh uh nerve. And so now if it reactivates, it

25:22 shingles and shingles is itching sensation, pain. And for some people,

25:31 can be very, very painful and can be to the point where you

25:37 wear clothing and can't really function normally a number of days. So there's

25:44 suggestion to vaccinate again against the herpes . So if you have a

25:53 as an older individual, you would less likely than you have to,

25:57 going to be able to fight off occurrence of that reoccurrence of that virus

26:04 the presentation of it in shingles. first of all, think about

26:08 this virus moves both in both It moved uh unter gradely. So

26:16 moved, it, it was already the surface and then it moved and

26:20 gradely the doo gang in a fashion dorsal part right, and sat down

26:28 the dorsal gang, dorsal gang and it moved, retrograde, it moved

26:37 an ether fashion. But through the gangling, remember we talk about how

26:41 can use viruses to trace connectivity and some of them are inter grade or

26:47 . This is an example where it move both directions but something has to

26:53 in order for it to move the direction and cause the shingles.

27:00 So secondary order neuron processing it, a matter sensory system. And so

27:06 have information. Remember that comes in and it ascends I ask you to

27:11 this 1st 2nd exam, the dorsal nuclei and the dorsal part of the

27:16 cord. These are the major ascending in the spinal cord and the ascend

27:23 the dorsal column nuclei. The way you read these diagrams again is cut

27:30 one here, OK. Through the cord, upper spinal cord, cut

27:36 two here is through me long. . And cut number three. In

27:44 particular case, we're targeting the parietal which contains the primary soma of sensory

27:54 and a part of the thalamus that the nucleus that carries that some amount

28:02 sensor information. So it goes from spinal cord into dorsal column nuclei,

28:10 level of Malaga where it crosses it becomes contralateral number of auditory.

28:20 just looked at auditor and we said the level of the brain stem,

28:23 information uh some remains of the some crosses over. Therefore, it

28:28 bi oral already and visual information became in the cortex right here. It

28:38 is completely contralateral. So some amount sensor information basically from right is processed

28:46 the last Mosen cortex. And the commands from the left motor cortex will

28:53 the right side of the bottom. . So from dorsal column nuclei,

28:59 crossover through what is called the medial projects into the ventral posterior nucleus of

29:08 thalamus. And then from ventral posterior , it goes into the primary Samata

29:14 cortical area S SWM. So the primary visual, one, primary auditory

29:20 a one primary SOMA S SWM area the parietal lobe. And this is

29:27 of the information from the neck down your face down, not from the

29:33 down from the face down. This a cut here through pads.

29:40 And the cut again to include the and the parietal cortex and the

29:48 Now, if it's not being processed the spinal cord, as I alluded

29:53 being processed by cranial nehi trigem which has a lot of large me

30:00 of receptors. Uh a lot of , sensory nerve ending axons in the

30:07 and that's the information and remember stomal nerve, so, so much

30:15 , but it's both. So it's and motor and this is the sensory

30:21 that will carry the sensor information, component will be responsible to contributing to

30:28 muscle movement. Ok. But the from the face comes through the trigeminal

30:34 innervates into the principal sensory trigeminal And the paws crosses over contralateral projects

30:44 the ventral posterior nucleus of the And from there into different area,

30:50 face area of the primary somatosensory cortical . S one OK. So

30:59 so good. Now, let's look maybe before we look at this uh

31:07 anatomy. Let's look overall at the of the body on the cortex.

31:16 this map is called somatotopic map. we have retinoic map point by point

31:23 presentation. We had tonotopic map, frequency map in the cochlea and we

31:31 some matter atop map. And there's features of this map. The map

31:36 not continuous in relation to the So the map is not continuous in

31:41 sense that here is the map for genitals and it's very close to the

31:50 . And here is the index finger it's very close to the head,

31:56 neither are really. So it's not lips, face this this forehead jump

32:05 this, why not neck someplace or or torso would be right. So

32:10 not continuous, right? The second it's not scaled to human body.

32:17 is a caricature of the homunculus, human body which illustrates which parts of

32:24 body have the most area dedicated to in the saliva, sensory cordage hands

32:34 a lot of touch, sensation because a lot of talking and also

32:42 with people through touch. Um so in general is huge and hands in

32:49 and huge the most sensitive areas. therefore you can see how much of

32:55 soma cortical space is dedicated to right? And how much of it

33:02 dedicated to the trunk. OK. trunk is hopefully much larger than my

33:14 , right? So if it if it was very important, it

33:18 have way more, but it's my face is actually taking up a

33:23 more area. The somatosensory cortex, indicates the importance of body parts,

33:28 body parts are more important than others touch, somatosensory sensations. Um and

33:37 and things in general, OK. talk about uh we're gonna come back

33:46 talk about the this finger map and I'll talk about this finger map way

33:53 all over the place now and talk about this finger map in a

34:00 . But let's talk about important organs other animals. So if we do

34:08 out of sensor sensation and we feel and if we want to get something

34:15 , with done with precision dexterous things like that, we will use

34:20 fingers think about rodents. You see , you know, picking up the

34:27 and signing things or typing. they do use their paws and they

34:32 use uh their uh their, their claws and whatnot. But a

34:39 area in the road and somatosensory cortex dedicated to the risk of patterns.

34:45 already alluded to that when we talked the evolutionarily differences in the external development

34:52 body parts. How important are those parts and how that is reflected on

34:58 anatomical structures in the brain. So lot of what rodents do is they

35:06 around and they whisk around. This how they process the information. This

35:11 how they touch things, not with , but with whiskers, it helps

35:15 get around, helps them survive, helps them find food, helps them

35:19 danger, helps them procreate. And , this is what the rodent

35:26 So a lot of this ulus from and homunculus for human Rulli for

35:34 As you can see a huge part the rodents body, his la sensory

35:39 is dedicated, a huge part of cortex is dedicated to information processing from

35:45 patent. And there's a beautiful anatomical there where in the primary somatosensory

35:52 you have this structure of barrels and referred to as barrel cortex in

35:57 And each one of these barrels processes from home, one single whisker.

36:03 just like there are 12345, five of whiskers, you'll find 12345 rows

36:13 barrels in the cortex. You're gonna six or seven whiskers in there.

36:18 gonna count 1234567 whiskers in the third and you'll find seven barrels in the

36:26 somatic cortex. Really cool. Because uh it's a system that is

36:33 developed. It's a system that is described and it's a great experimental

36:40 You can wiggle uh a single whisker you can record activity from a single

36:50 in the cortex. So it's a system. You can wiggle a whisker

36:54 see the activity in the contralateral cortex a single barrel. And so from

37:01 whisker, you have the nerve you have the trigeminal ganglia, remember

37:05 trigeminal nerves that will carry the information they'll come in into the trigeminal

37:11 OK. It will carry that information that we just described until it reaches

37:20 the way the primer amount of sensory . And so you'll have by wiggling

37:25 C two whisker here. So it's , abc D E rows, you're

37:31 the whisker in the third row and can actually see an activation of a

37:35 barrel C two whisker C two barrel , the really nice experimental system.

37:44 uh there are dyes that we talked already in this course, we talked

37:50 calcium sensitive dyes. So we're now about experimental neuroscience. We talked about

37:55 sensitive dyes, we talked about optical signal imaging, right. So voltage

38:02 dyes represent activity or depolarizations and changes membrane potentials. And so this is

38:10 you wiggle whisker C two, 10 . After wiggling C two, if

38:16 have a dye that you applied on tissue, the neurons that are active

38:21 the whisker C two will show you map. So this is the 10

38:25 later the map for C two and what this information is going to

38:31 So these are brain maps, And they're spreading, they're moving through

38:35 tissue, they're spreading. Because that here, excited information gets communicated to

38:42 barrels to adjacent cortex areas, association to process that information as a

38:48 So some 26 milliseconds later just wiggling , C two whisker from a single

38:54 two barrel map. This brain map spread in a wavelike fashion, we

39:01 it like a brain wave. So are brain maps and brain waves.

39:06 there's a brain map for C two , you wiggle E two Whisker and

39:12 E two. So I'm referring to two and E two. This is

39:17 D E, the rows, the rows, wiggle C two. This

39:22 C two cortical map. Wiggle E . This is E two cortical map

39:26 some 18 and then 26 milliseconds it shows the spread of that

39:33 the activation of larger areas of the just by wigging a single whisker.

39:40 . Now, in this experiment, learned about things like AY and we

39:48 about an MD A receptor in the section of this course. And we

39:53 that these glutamate akin and MD A channels, they all have their own

40:01 or blockers. So in this C N Q X C N Q

40:08 and A PV or A P five applied on this area here in the

40:15 column and the in the area that to C two. So you blocked

40:22 activity and you block the formation of map and there is a little bit

40:27 residual activation that you may be But overall by blocking here excitation uh

40:38 and, and MD A receptor, block the spread of this excited

40:43 Now you have manipulated what we call spatial temporal properties of the map,

40:48 spatial temporal properties. How where is in space? Where is it in

40:53 ? How does it change over time over space? E two Whisker?

40:59 problem. There's no C N Q applied on E two Whisker. And

41:03 still see this beautiful spreading map of from E two whisper. So an

41:09 can be done now to see how can change the plasticity in the

41:16 For example, an equivalent could be where you block activity in the

41:20 There are simple experiments where a single , a few whiskers can be cut

41:26 see what effect it has on the activation. And it can reveal a

41:30 of information especially on the signaling on connectivity of a single whisker to the

41:37 of the brain on the chemistry underlying . Uh and uh and how to

41:44 these different brain maps and these different waves. Now in, in animals

41:51 uh humans and in this case, monkeys, there is a significant area

41:59 the primary somatosensory cortex that is dedicated the palm and that is dedicated in

42:06 case to the finger. So this the finger area in the somatosensory cortex

42:14 just like you have five digits. in this case, monkeys, five

42:19 , 12345, there are digit, digit, 2345 areas that you can

42:27 in the primary somatosensory cortex. Now one of these digits, primary somatosensory

42:39 which receives inputs from ventral posterior This neurons in the primary somatosensory cortex

42:47 responsive to samita sensor stimuli. If impair somatosensory cortex, if there's a

42:57 , somatosensory cortex, if there's traumatic injury or vascular injury, in one

43:03 of the mito sensory cortex, you lose the feeling mito sensory information from

43:09 opposite side of the body. If stimulate some out of sensor cortex on

43:15 side, it's gonna feel like, , I feel heat in my coming

43:19 my left hand. Although there's no on your left hand, but you

43:22 recreate the somatosensory sensations by simply stimulating primary somatosensory cortex neurons. And if

43:31 look at the finger map, which quite precise and a lot of somatosensory

43:37 area is dedicated to the finger We have slowly adapting and we have

43:43 adapting neurons and the columns and the is structured the six letter structure.

43:48 the Samay cortex, we won't get the details of it that will be

43:52 to each digit. So digit one have its own fast and slowly adapting

43:59 will be processed and be slowly and adapting neuronal columns. Now, in

44:05 cortex, so you saw ocular dominance . Now, if you look in

44:10 digit map and the primary somatosensory you're seeing this rapidly and slowly adapting

44:17 columns that process information from each And uh you know, maybe I

44:24 said that at the beginning of this , but I kind of asked you

44:32 uh think about something. How was phone call done 40 years ago?

44:42 in? Yes. Yeah. There this thing called pay phones. You

44:46 to have change or you call 1 call, collect or something like

44:54 So, and how much time 40 ago people spend on the phone if

45:02 were not, you know, phone or dispatchers or something like that.

45:09 typically, you know, when I little, uh and the cell phones

45:17 in the nineties really. So you , you don't know the world,

45:21 of you don't know the world without phones. You, you, we

45:26 . And that world was quite different to make a phone call, you

45:31 to go to a spot like it's like you were carrying the phone,

45:35 with you. You know, it , you would have to like drag

45:38 whole phone booth from the street. , so that's one thing. So

45:42 would come off the location if it the house, maybe you had two

45:47 . If you were really, you , slick, you had a really

45:50 cord so you could walk around where were talking with the phone and then

45:55 phones came into play in the, the eighties. And then when the

46:01 cell phones came out or they were satellite phones, they were the size

46:05 like this keyboard and only, you , super wealthy, uh people had

46:13 in their cars. So it was like, like the phones and the

46:18 that we have these days. So does that phone call look like?

46:22 , ok, I would go to living room, pick up the phone

46:28 , you know, punch in the or dial and then you wait for

46:32 beep, you know, and then the person doesn't pick up, you

46:38 a voicemail and then you hang up the person picks up, you stay

46:44 the phone, but not for Because, you know, you're,

46:48 standing here in the living room or . So, you know, you

46:51 be, you cannot move. So you have to move, you have

46:54 leave the phone and go to another or you get a book, come

46:58 , you know. Yes, I'm this. So, and then,

47:01 know, you would do this maybe times a day. Like your parents

47:05 really care if you didn't call them 15 minutes and texting them back.

47:10 were no texts really. If you in a hospital, you would get

47:13 beeper. So people had beepers in hospital. But you would do this

47:18 23 times a day unless you were , obsessed about somebody, you

47:22 like, uh, it was your . But other than that, you

47:28 interact with the phone but maybe 15 minutes a day, you

47:33 if you're in love with a girl a boy, you know, and

47:37 for a long time, you that happened. But then the bill

47:41 high too. It was expensive and heard it from your parents or your

47:45 or your roommates, you know. anyways and, uh, that was

47:51 , and, uh, this is ok. So what do we do

47:58 our cell phones? Is we hold typically like this, like this,

48:08 this, like this, we use typically with one or two fingers all

48:15 long. Tap, tap, tap , swipe, swipe, tap,

48:19 , tap, swipe, swipe swipe you look at the screen time,

48:24 , 10 hours of screen time. means you did this, the

48:29 tap, tap, swap, swap and your neck and C three

48:33 four digital net for 6 to 10 . And you're like, oh my

48:38 , I'm so tired. I can't anything today, you know.

48:43 hm. And where am I going this? You guys remember the brains

48:47 plastic, right? And I talked this course that said that you have

48:52 critical period of development where we have lot of plasticity and the brain can

48:57 itself, but you can also change permanently. But there is a level

49:00 plasticity that is also present in our in adult brains. And in

49:07 you guys are too late because you your lives with this. I had

49:11 change into this when I was in twenties from, you know, that

49:15 or payphone situation into this. So had a different plasticity and I have

49:19 develop it. You're way more far at using these devices because your plasticity

49:25 grew up with it just like as foreign language. You grew up with

49:30 devices, digital devices that, that, that a lot of our

49:34 didn't. So now you have this map that digital digit map, it's

49:40 digit map, 1234 digits on the , 12345 areas in the primary amount

49:47 sensory cortex is processing information from the digits. Ok. Ok. Now

49:52 monkey lost the middle finger when I a graduate student in Louisiana State University

50:00 Center in New Orleans. It was a monkey room. We had an

50:05 room, we'd walk up to the . There was one that would show

50:08 middle fingers all the time and just for you to look and, and

50:11 you middle fingers, somebody like taught to mean something against us. So

50:15 one lost the middle finger. And there's no longer a map with digital

50:23 and the two maps from digit two digit four have increased. And that

50:29 that there is no more space in somatosensory cortex for digit three, but

50:34 more space for digit two and digit . That means that they're becoming more

50:38 in the absence of this middle Now, does it have to be

50:43 radical? No, it can be radical as using a cellphone continuously.

50:48 this is an experiment where you have and digit two and digit three are

50:56 being stimulated with this stimulus disk which rotated. So they had the station

51:03 of the disc is constantly touching. that's an equivalent of doing this constantly

51:10 swiping and tapping and just repeating it a number of days. What it

51:19 ? It increases that area, that of digits, two and digits three

51:25 the expense of the digits. And why sometimes it's becoming more difficult when

51:31 doing another task is like, can still move these two fingers? You

51:35 , and that's why because you shrunk area with the fingers, you shrunk

51:41 area in the cortex or the fingers are not as active. Uh So

51:48 that we are plastic, that our are plastic and that our habits and

51:54 know, over the years, 6 8 hours a day can, can

51:59 uh reflective to your health and definitely to your brain maps and the reorganization

52:08 the structure based on the plasticity in different cortical areas. OK.

52:15 the last uh portion of this we're gonna watch a, a tremendous

52:20 talk by Dr Ramachandran. And as watch this TED talk, I want

52:25 to take notes. There are three . It's about 20 minutes long.

52:29 we'll probably end right about 23 We'll end maybe a little bit after

52:34 15. I'll write down the information I think is important for you to

52:39 from this talk. And it is to Sama center system, it is

52:43 to plasticity and it is related to disorders. Um Well, as Chris

52:54 out, I study the human the functions and structure of the human

52:58 . And I just want you to for a minute about what this entails

53:02 . Is this massive jelly, £3 of jelly you can hold in the

53:08 of your hand and it can contemplate vastness of interstellar space. It can

53:14 the meaning of infinity and it can itself, contemplating on the meaning of

53:20 . And there is this peculiar recursive that we call self awareness, which

53:25 think is the Holy Grail of Neuroscience Neurology. And hopefully someday we'll understand

53:30 that happens. OK. So how you study this mysterious organ? I

53:35 , you have 100 billion nerve little wisps of protoplasm interacting with each

53:42 . And from this activity emerges the spectrum of abilities that we call human

53:47 and human consciousness. How does this ? Well, there are many ways

53:50 approaching the functions of the human One approach, the one we use

53:56 is to look at patients who have damage to a small region of the

54:00 or there's been a genetic change in small region of the brain. What

54:04 happens is not an across the board in all your mental capacities. A

54:09 of blunting of your cognitive ability. you get is a highly selective loss

54:14 one function with other functions being preserved . And this gives you some confidence

54:18 asserting that that part of the brain somehow involved in mediating that function.

54:22 you can then map function onto structure then find out what the circuitry is

54:27 to generate that particular function. So what we're trying to do. So

54:32 me give you a few striking examples this. In fact, I'm giving

54:35 three examples, six minutes each during talk. The first example is an

54:40 syndrome called Grass syndrome. If you at the first slide, then uh

54:46 the temporal lobes, frontal lobes, lobes, OK. The lobes that

54:50 the brain and if you look tucked inside the inner surface of the temporal

54:56 , you can't see there is a structure called the fusiform gyrus. And

55:00 been called the face area in the . Because when it's damaged, you

55:04 no longer recognize people's faces, you still recognize them from their voice.

55:08 , oh yeah, that's Joe. you can't look at their face and

55:12 who it is right. You can't recognize yourself in the mirror. I

55:15 , you know, it is, you because when you wink it winks

55:18 you know it's a mirror, but don't really recognize yourself as yourself.

55:24 . Now, that syndrome is well , it's caused by damage to the

55:27 . But there's another rare syndrome so . In fact that very few physicians

55:31 heard about it, not even this is called the carb graft

55:36 And that is a patient who's otherwise normal, who's had a head injury

55:41 out of coma, otherwise completely He looks at his mother and says

55:46 looks exactly like my mother, this , but she's an impostor. She's

55:49 other woman pretending to be my Now, why does this happen?

55:54 would somebody and this person is perfectly and intelligent in all other respects?

55:58 when he sees his mother, his kicks in and says, not

56:01 Now, the most common interpretation of , which you find in older psychiatry

56:05 is a Freudian view. And that that this chap and the same argument

56:11 to women by the way. But just talk about guys when you were

56:14 little baby and a young baby, had a strong sexual attraction to your

56:18 . This is the so called U of Freud. I'm not saying I

56:22 this, but this is the standard view. And then as you grow

56:27 , the cortex develops and inhibits these sexual urges towards your mother. Thank

56:32 . Otherwise, we would all be aroused when you saw your mother.

56:37 then what happens is there is a to your head, damaging the

56:41 allowing these latent sexual urges to flaming to the surface and suddenly and

56:47 , you find yourself being sexually aroused your mother and you say, my

56:50 , if this is my mom, come I'm being sexually turned on?

56:53 some other woman. She's an It's the only interpretation that makes sense

56:58 your damaged brain. Never made much to me this argument. It's very

57:04 as all Freudian arguments are didn't make sense because I have seen the same

57:12 , a patient having the same delusion his pet poodle. He'll say

57:17 this is not fifi, it looks like fifi, but it's some other

57:22 . Right. Now, you try the Freudian explanation there. You,

57:26 start talking about the latent beastiality in humans or some such thing, which

57:31 quite absurd. Of course, now really going on. So to explain

57:35 curious disorder, we look at the and functions of the normal visual pathways

57:40 the brain. Normally, visual signals in into the eyeballs, go to

57:43 visual areas in the brain. There in fact 30 areas in the back

57:47 your brain concerned with just vision. after processing all that, the message

57:51 to a small structure called the fusiform . Um where you perceive faces,

57:57 are neurons there that are sensitive to , you can call it the face

58:00 of the brain, right? I about that earlier. Now, when

58:04 area is damaged, you lose the to see faces, right? But

58:08 that area, the message cascades into structure called the Amygdala. In the

58:13 system, the emotional core of the and that structure called the Amygdala gauges

58:17 emotional significance of what you're looking Is it prey? Is it

58:22 is it mate or is it something trivial like a piece of lint or

58:26 piece of chalk or, or, , or I don't want to point

58:29 that but, or a shoe or like that. Ok. Which you

58:32 completely ignore. So if the Amygdala excited and this is something important,

58:36 messages then cascade into the autonomic nervous . Your heart starts beating faster.

58:41 start sweating to dissipate the heat that going to create from exerting muscular

58:47 And that's fortunate because you can put electrodes on your palm and measure the

58:51 change in skin resistance produced by So I can determine when you're looking

58:56 something, whether you're excited or whether aroused or not. Ok. And

59:00 get to that in a minute. my idea was when this chap looks

59:04 an object, uh when he looks his any object for that matter,

59:08 goes to the visual areas. And , and it's processed in the fusiform

59:13 . And you recognize it as a plant or a table or your mother

59:18 that matter. OK. And then message cascades into the Amygdala and then

59:22 down the autonomic nervous system. But in this chap, that wire that

59:27 from the Amygdala to the limbic the emotional core of the brain is

59:31 by the accident. So because the is intact, the chap can still

59:36 his mother and says, oh this looks like my mother. But

59:40 the wire is cut to the emotional . He said, but how come

59:42 it's my mother, I don't experience warmth or terror as the case may

59:48 , right? OK. And therefore says, how do I account for

59:53 inexplicable lack of emotions? This can't my mother. It's some strange woman

59:58 to be my mother. How do test this? Well, what you

60:00 is if you take any one of here and put you in front of

60:03 screen and measure your galvanic skin response show pictures on the screen. I

60:08 measure how you sweat. When you an object like a table or an

60:12 . Of course, you don't If I show you a picture of

60:15 lion or a tiger or a you start sweating right? And believe

60:19 or not, if I show you picture of your mother, I'm talking

60:22 normal people. You start sweating. don't even have to be Jewish.

60:27 . Now what happens? What happens you show this patient, you take

60:33 patient and show him pictures on the and measure his galvanic skin response tables

60:38 chairs and lint, nothing happens as normal people. But when you show

60:43 a picture of his mother, the skin response is flat. There's no

60:48 reaction to his mother because that wire from the visual areas to the emotional

60:53 is cut. So his vision is because the visual areas are normal.

60:57 emotions are normal, he'll laugh, cry so on and so forth.

61:00 the wire from vision to emotions is and therefore he has this delusion that

61:05 mother is an impostor. It's a example of what the sort of thing

61:08 do take a bizarre, seemingly incomprehensible psychiatric syndrome and say that the standard

61:14 view is wrong, that in you can come up with a precise

61:18 in terms of the known neuro anatomy the brain. By the way,

61:21 this patient then goes and mother phones an adjacent room phones him and he

61:28 up the phone and he says, , mom, how are you?

61:30 are you? There's no delusion through phone. Then she approaches him after

61:35 hour. He says, who are ? You look just like my

61:37 Ok. The reason is there's a pathway going from the hearing centers in

61:41 brain to the emotional centers and that's been cut by the accident. So

61:46 explains why with a phone, he his mother, no problem when he

61:51 it in person. He says it's , he says it's an impostor.

61:55 . How is all this complex circuitry up in the brain? Is it

61:59 genes or is it nurture? And approach this problem by considering another curious

62:04 called phantom limb. And you all what a phantom limb is when an

62:09 is amputated or a leg is amputated gangrene or you lose it in

62:13 For example, in the Iraq it's now a serious problem. You

62:17 to vividly feel the presence of that arm and that's called a phantom arm

62:21 a phantom leg. In fact, can get a phantom with almost any

62:24 of the body, believe it or , even with internal viscera. I've

62:28 patients with the uterus, removed hysterectomy have a phantom uterus, including phantom

62:36 cramps at the appropriate time of the . And in fact, one student

62:40 me the other day, do they Phantom P MS subject ripe for scientific

62:46 ? But we haven't pursued that. . Now, the next question

62:50 what can you learn about phantom limbs doing experiments? One of the things

62:55 found was about half the patients with limbs claim that they can move the

62:59 . It'll pat his brother on the , it'll answer the phone when it

63:03 , it'll wave goodbye. These are compelling vivid sensations. Patients are not

63:07 . He knows that the arm is there. But nevertheless, it's a

63:10 sensory experience for the patient. But , about half the patients, this

63:16 happen the phantom limb. They'll say , the phantom limb is paralyzed.

63:20 fixed in a clenched spasm and it's painful. If only I could move

63:25 , maybe the pain will be Now, why would a phantom limb

63:29 paralyzed? It sounds like an oxymoron we look at the case sheets.

63:33 we found was these people with the phantom limbs. The original arm was

63:39 because of the peripheral nerve injury. actual nerve supplying the arm was severed

63:44 cut by say a motorcycle accident. the patient had an actual arm which

63:49 painful in a sling for a few or a year. And then in

63:53 misguided attempt to get rid of the in the arm, the surgeon amputates

63:57 arm and then you get a phantom with the same pains, right?

64:02 this is a serious clinical problem. become depressed. Some of them are

64:06 to suicide. Ok. So how you treat this syndrome? Now,

64:10 do you get a paralyzed phantom When I looked at the case

64:13 I found that they had an actual and the nerve supplying the arm had

64:18 cut and the actual arm had been and lying in a sling for several

64:24 before the amputation. And this pain gets carried over into the phantom

64:31 Why does this happen when the arm intact but paralyzed? The brain sends

64:36 to the arm, the front of brain saying move but it getting visual

64:40 saying no move, no move, move, no. And this gets

64:46 into the circuitry of the brain and call this learned paralysis. Ok.

64:51 brain learns because of this Heben associative that the mere command to move the

64:58 creates a sensation of a paralyzed And then when you the arm,

65:02 learned paralysis carries over into the, your body image and into your

65:08 Ok. Now, how do you these patients? How do you unlearn

65:12 learned paralysis? So you can relieve of this excruciating clenching spasm of the

65:18 arm. Well, we said, if you now send the command to

65:23 phantom but give him visual feedback that obeying his command, right? Maybe

65:27 can relieve the phantom pain. The cramp. How do you do

65:31 Well, virtual reality, but that millions of dollars. So I hit

65:35 a way of doing this for But don't tell my funding agencies,

65:42 you do is you create what I a mirror box. You have a

65:45 box with a mirror in the middle then you put the phantom. So

65:49 first patient Derek came in. He his arm amputated 10 years ago.

65:53 had a brachial abul. So the were cut, the arm was

65:57 lying in his sling for a year then the arm was amputated. He

66:00 a phantom arm, excruciatingly painful and couldn't move it. It was a

66:03 phantom lung. So he came there I gave him a mirror like that

66:07 a box. OK? Which I a mirror box, right? And

66:12 patient puts his phantom left arm which clenched and inspires him on the left

66:16 of the mirror and the normal hand the right side of the mirror and

66:20 the same posture, the clenched posture looks inside the mirror. And what

66:25 he experience? He looks at the being resurrected because he's looking at the

66:31 of the normal arm in the mirror it looks like this phantom has been

66:35 . Now, I said now, wiggle your phantom, your real fingers

66:39 move your real fingers while looking in mirror. He's going to get the

66:43 impression that the phantom is moving, ? That's obvious. But the astonishing

66:47 is the patient then says, oh God, my phantom is moving again

66:51 the pain, the clenching phantom is . I remember my first patient who

66:55 in. Thank you. Bye. first patient came in and he looked

67:03 the mirror and I said, look your reflection of your phantom. And

67:06 started giggling. He says, I see my phantom but he's not

67:10 He knows it's not real. He it's a mirror reflection, but it's

67:12 vivid sensory experience. Now, I , move your normal hand. And

67:17 , he said, oh, I move my phantom. You know that

67:19 painful. I said, move your hand. And he says, oh

67:22 God, my phantom is moving I don't believe this and my pain

67:25 being relieved. OK? And then said, close your eyes, he

67:28 his eyes and move your normal Oh Nothing. It's clenched again.

67:32 ? Open your eyes. Oh my . Oh my God. It's moving

67:35 . It was like a kid in candy store. So I said,

67:39 , this proves my theory about learned and the critical role of visual

67:44 But I'm not going to get a Prize for getting somebody to move his

67:47 limb completely useless ability if you think it. But but then I started

67:56 maybe other kinds of paralysis that you in, in, in, in

68:00 , like stroke, focal dystonias, may be a learned component to this

68:04 you can overcome with the simple device using a mirror. So I

68:08 look Derek, well, first of , the guy can't just go around

68:11 a mirror to alleviate his pain. said, look Derek, take it

68:14 and practice with it for a week two. Maybe after repeated practice,

68:19 can dispense with the mirror, unlearn paralysis and start moving your paralyzed arm

68:23 then relieve yourself of pain. So said, OK, and he took

68:26 home. I said, look, after all, $2 take it

68:29 So he took it home and after weeks, he phones me and he

68:32 , doctor, you're not gonna believe . I said one. He said

68:35 gone. I said, what's I thought maybe the mirror box was

68:40 . He said, no, no, you know, this Phantom

68:42 had for the last 10 years, disappeared. And I said, I

68:46 worried. I said, my I mean, I've changed this guy's

68:49 image. What about human subjects? and all of that? And I

68:53 , Derek, does this bother He said no, last three

68:56 I've not had a phantom arm and , no phantom elbow pain, no

69:01 , no phantom forearm pain. All pains are gone away. But the

69:05 is I still have my phantom fingers from the shoulder and your box doesn't

69:10 . So can you change the design put it on my forehead so I

69:14 , you know, do this and my phantom fingers? He thought I

69:18 some kind of magician. Does this ? It's because the brain is faced

69:21 tremendous sensory conflict. It's getting messages vision saying the phantom is back.

69:27 the other hand, there's no muscle signals saying that there is no

69:31 , right? And your motor command there is an arm. And because

69:35 this conflict, the brain says to with it, there is no

69:38 there is no arm, right? goes into sort of denial. It

69:41 the signals and when the arm the bonus is the pain disappears because

69:46 can't have disembodied pain floating out there space. So that's the bonus.

69:51 , this technique has been tried on of patients by other groups in

69:54 So it may prove to be valuable a treatment for phantom pain. And

69:58 people have tried it for stroke, stroke, you normally think of as

70:03 to the fibers, nothing you can about it. But it turns out

70:07 component of stroke paralysis is also learned and maybe that component can be overcome

70:13 mirrors. This has also gone through trials helping lots and lots of

70:18 Ok. Let me switch gears Now the third part of my talk,

70:22 is about another curious phenomenon called This is discovered by Francis Galton in

70:27 19th century. He was a cousin Charles Darwin. He pointed out that

70:31 people in the population who are otherwise normal had the following peculiarity. Every

70:37 they see a number, it's colored is blue, seven is yellow,

70:42 is nine is indigo. OK. in mind these people are completely normal

70:48 other respects. OK? Or C# tones evoke color C# is blue f

70:54 is green. Uh another tone might yellow, right? Why does this

70:59 ? This is called synesthesia Galton called synesthesia. Mingling of the senses in

71:04 . All the senses are distinct. people muddle up their senses. Why

71:07 this happen? Another two aspects of problem are very intriguing synesthesia runs in

71:12 . So Dalton said this is a basis, a genetic basis.

71:16 synesthesia is about and this is what me to my point about the main

71:21 of this lecture, which is about . Synesthesia is eight times more common

71:26 artists, poets, novelists, and creative people than in the general

71:30 Why would that be? I'm going answer that question. It's never been

71:33 before. OK. What is What causes it? Well,

71:37 there are many theories. One theory they're just crazy. Now, that's

71:40 really a scientific theory so you can about it. OK. Another theory

71:44 there are acid junkies and potheads. . Now, there may be some

71:48 to this because it's much more common in the Bay Area than in San

71:52 . Ok. Now, the third is that, well, let's ask

71:57 what's really going on in synesthesia, ? So, but the color area

72:02 the number area are right next to other in the brain in the fusiform

72:05 . So we said there's some accidental wiring between color and numbers in the

72:11 . So every time you see a you see a corresponding color and that's

72:15 you get synesthesia. Now, remember , why does this happen? Why

72:18 they be cross wired in some Remember I said it runs in families

72:22 gives you the clue. And that there is an abnormal gene and in

72:27 gene that causes this abnormal cross wiring all of us, it turns out

72:31 are born with everything wired to everything . So every brain region is wired

72:36 every other region and these are trimmed to create the characteristic modular architecture of

72:41 adult brain. So there's a gene this trimming. And if that gene

72:46 , then you get deficient trimming between brain areas. And if it's between

72:51 and color, you get number color . If it's been tone and

72:54 you get tone color synaesthesia so so good. Now what if this

72:58 is expressed everywhere in the brain? everything is cross connected. Well,

73:02 about what artists, novelists and poets in common, the the ability to

73:08 in metaphorical thinking, linking seemingly unrelated such as it is the yeast and

73:14 is the sun. But you don't Juliet is the son. Does that

73:17 she's a glowing ball of fire. mean schizophrenics do that, but it's

73:21 different story, right? Normal people she's warm like the sun, she's

73:25 like the sun, she's nurturing like sun instantly you form the links.

73:29 , if you assume that this greater wiring and concepts are also in different

73:34 of the brain, then it's going create a greater propensity towards metaphorical thinking

73:40 creativity in people with synesthesia. And the eight times more common incidence of

73:46 among poets, artists and novelists. . It's a very phonological view of

73:50 . The last demonstration. Can I one minute? OK, you are

73:57 synesthetic but you're in denial about Here's what I call Martian alphabet just

74:03 your alphabet. A is A B BC, is C different shapes for

74:08 phonemes right here. You've got Martian . One of them is Kiki,

74:12 of them is Buba. So he's ask this question of his audience.

74:20 how many of you think that this Kiki? And this is Buba.

74:29 many of you think that this is ? And this is OK, see

74:38 happens in the audience? Which one Kiki? And which one is?

74:41 many of you think that's Kiki? that's Buba? Raise your hands?

74:44 , one or two mutants. How of you think that's Buba? That's

74:48 . Raise your hands. 99% of . Now, none of you is

74:51 Martian. How did you do It's because you're all doing a cross

74:56 synesthetic abstraction. Meaning you're saying that sharp inflection key key in your auditory

75:03 , the hair cells being excited, key mimics the visual inflection, sudden

75:09 of that jagged shape. Now, is very important because what it's telling

75:13 is your brain is engaging in a . It's just, it looks like

75:16 silly illusion. But these photons in eye are doing this shape and hair

75:22 in your ear are exciting the auditory . But the brain is able to

75:27 the common denominator. It's a primitive of abstraction. And we now know

75:31 happens in the fusiform of the brain when that's damaged these people lose the

75:39 to engage in Buba Kiki, but also lose the ability to engage in

75:43 . If you ask this guy, all that glitters is not gold.

75:47 does that mean? The patient well, if it's metallic and

75:50 it doesn't mean it's gold, you to measure its specific gravity.

75:53 So they completely missed the metaphorical So this area is about eight times

75:59 size in higher, especially in humans in lower primates. Something very interesting

76:03 going on here in the Anglo because the crossroads between hearing vision and touch

76:10 in humans and something very interesting is on. I think it's a basis

76:14 many uniquely human abilities like abstraction, and creativity. All of these questions

76:20 philosophers have been studying for millennia, scientists can begin to explore by doing

76:25 imaging and by studying patients and asking right questions. Thank you.

76:30 one of the, one of my uh uh uh fav favorite talks,

76:37 talks. Uh This will be in quiz and the exam, uh the

76:42 uh conditions that he was referring to a loss of function. Uh But

76:50 this case, delusion, the areas the brain that are involved and the

76:56 test, the galvanic skin response, phantom limb, you use neuro box

77:02 it's like lung paralysis and the somatosensory areas. And it can be likened

77:08 stroke and synaesthesia intermingling of census is wiring between the areas that process the

77:16 and the color areas uh and the portions which are mentioned here of the

77:23 . For here, cob grass is gyrus amygdala limbic system for emotional

77:30 Here, it's so not a sensory . And here it's the fusiform virus

77:35 the angular gyrus. And as he , something is very interesting is going

77:39 in the angular gyrus. It it possibly evolving structure and actively evolving structure

77:46 humans. Uh And uh some uh that have synaesthesia, they will literally

77:55 numbers of colors. Sometimes they will perceive sound and color. So if

78:02 is a inter mingling or cross wiring connectivity between these closely related areas,

78:11 color uh sound areas. Uh Some will have incredible abilities of listening to

78:19 wands and playing a whole piano concerto uh because they visualize it as,

78:27 colors and it's easier for them to recreate it. So this is

78:31 synaesthesia. And as we saw, all synesthetic to a certain degree because

78:36 use, learned what we've learned, use association, we use cross modal

78:44 that with, with that we derive you call the common denominator of auditor

78:50 visual information, describing something what it . Um Most of us. So

78:57 you very much. Have a great and I will see everyone on

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