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00:00 So today we're going Thio very quickly what we discussed about the somatic sensory

00:06 and then watch a couple of very videos and talk about brain imaging and

00:13 ourselves off the basically some of the and some of the anatomy and function

00:21 we learned during the course. So sensor system. As you know,

00:27 have the skin. We have the endings in the skin. You

00:31 ah, nerve endings that are either small or large, receptive fields rapidly

00:38 slowly adapting where you have areas like and face. You need higher

00:45 so you have better two point There you have smaller, receptive fields

00:52 sensitive. You have four types of three mile unaided and one and Meilen

00:58 carrying the information of appropriate reception sensations, pain, temperature and,

01:07 , temperature, pain and itch and of this information below the neck enters

01:13 the spinal cord and through the sending and forms the rest of the

01:19 N s. We discussed derma tomes each Dermot, um, is essentially

01:25 Nana Tom ical representation off the communication one single spinal normal one side and

01:33 know that the spinal nerves are divided like the vertebra to cervical thoracic lumber

01:38 sacred regions. And we learned that , for example, will delineate one

01:48 the Dermot owns because the herpes virus remains dormant after chicken pox, typically

01:54 is only in one dorsal root ganglion one side, delineating that particular Dermot

02:01 , which is kind of a map correspondence to that particular spinal nerve segment

02:07 the skin. So all of the , as we discussed from the spinal

02:12 , will go through the ascending Darcel , and we'll cross over at the

02:19 off right here off medulla blank The doors will call them nuclear.

02:25 will cross over and we'll innovate the posterior nuclear's off the bow Lemus.

02:31 from there, the primaries amount of cortex or s one neo cortex that

02:37 the matter. Sensor information in the lobe now touch pathway that is processed

02:45 essentially the neck and up that subservient by the cranial nerve, trigeminal

02:54 five cranial nerve five and these air McCann a receptor accents from the

03:01 Remember the cranial nerve? Five. censoring Boehner so the sensor informational go

03:09 in the motor information will come has a motor components. So now

03:16 sensor information will travel and cross over the level right here at the level

03:23 the ponds and the principal sensory gentlemen, will nucleus and projected to

03:29 ventral posterior who is of the And from there, Phil,

03:33 a cortical projections will go into the . Sensory area one to matter.

03:39 Nucleus Area one. So we have maps. We already discussed the

03:45 which is this discontinues disproportionate map off human body as it is being represented

03:52 the amount of space that is dedicated processing some out of sensor information from

03:57 parts of the body. And when looked at the digits, we see

04:02 each digit has its own anatomical has its own sort of a

04:08 The representation for each digit on This is a matter of toppy.

04:15 this a matter topic map that we're is a map for all of the

04:22 from which you have sensations across the . It's discontinuous. It's not scaled

04:28 human body and certain parts of the on this map based lips fingers the

04:36 occupy Ah, lot more space than parts, um, of the

04:42 despite the fact that physically those parts the body a larger in the periphery

04:47 in the C N s, those the mawr important parts. And it

04:52 depends on the type of the organism the environment in which these organisms are

04:58 and their brains. Um, this determine the maps and the specificity for

05:06 somatic talky, uh, in rodents well develops a matter Topic map is

05:12 map from the rodent whisker pad where one of the bris a or each

05:18 of the whiskers has a barrel like representation. Each one of these barrels

05:26 the primaries amount of sensory cortex of rat rig calculus each one of these

05:33 or presents an individual whisker and somatic from that individual whisker. So all

05:41 these barrels combined together here, each of these represent the five rows of

05:49 and each one of the barrels represent whisker information in the primary cortex is

05:56 processed primary somatic sensory cortex from just one specific whisker. And so we

06:03 that this system lends itself thio some interesting manipulations, and these experimental manipulations

06:11 now allow us to determine certain very questions. Help us answer questions.

06:19 example, can we change the Can we? How? How can

06:23 alter this map in the cortex? happens if we change something on the

06:30 ? What happens if we change the of the activity in just one

06:35 Does that whisker ifit's inactivated? Will be able to see that map in

06:41 somatic sensory cortex? What happens if cut off one whisker? What?

06:46 happens if we cut off to What happens to this barrel structure?

06:51 discuss critical period of development, and said there's a lot of plasticity on

06:55 , recalled it With one island's future just six days, you could have

07:01 permanent change in the New York cortical , where you would have changes in

07:07 projections that air going into the neocortex by depriving animal of vision in one

07:13 for 3 to 6 days. And could have a permanent change in the

07:18 arrangements and the maps of the level the cortex. So here. The

07:24 is you are recording activity from sea whisker and e to whisker. And

07:30 can see that the C two whisker to whisker they get activated. Here

07:34 little dots of activity and then the . After the activation of the primaries

07:40 of sensor cortex and subsequently spreads. the C two whisker map and the

07:46 to was come up In this the the experimenters injected seeing Q X

07:52 a PV, which blocks glue dermatologic channels, glutamate receptor channels. So

08:00 means that there is no synoptic activity the level of the whisker. So

08:05 the synoptic activity, when glue excited or synaptic activity is blocked,

08:09 just injected at the layer at the C two. Now, when you

08:15 whisker see too, you don't see activity in the brain, so you

08:19 see how the activity map of the changed when you inactivated whisker C two

08:25 this could be a consequence of a manipulation. This could be a consequence

08:30 a trauma to whisker pad, a of a whisker, Um and but

08:38 you stimulate e to the whisker that haven't the fact that it's just one

08:43 over from C E to area, can still reproduce the map that you

08:50 seeing earlier before you inactivated whisker C . So now you can have very

08:58 manipulations off these maps. And how record activity in this maps is,

09:05 is really the naps and the cortex now representing off what is happening in

09:10 periphery and any changes that may be in the periphery. Any changes in

09:17 levels of activity will then be represented the changes in the cortical maps.

09:24 as you saw with the projections into four, primary visual cortex is changes

09:31 be permanent. So loss of the loss of the inputs could be

09:37 And the restructuring off the cortex can be really significant. So we looked

09:45 an example there quickly. We started this example off the digit map on

09:55 experiment that was done. Been looking the monkey brain maps. So the

10:03 hand here, the left hand map found on the right hemisphere. Remember

10:10 somatic sensory fibers crossover. So it's lateral information that we process so and

10:17 have digit 12345 from the monkey this is Monkey Palm and these are

10:24 actual digits Fingers, monkey fingers. if you live in some matter sensor

10:31 , You have area in this primary sensory cortex that is dedicated thio Digit

10:38 D, one D two D three four d five. And then what

10:44 if you have a surgical removal of third finger of digit three? Then

10:53 look back in this map and you no longer had any matter sensory cortex

11:01 is dedicated to digit three because it been removed. And what happens is

11:08 a matter sensor cortex and the synopsis the communication between neurons in this area

11:15 the loss of the inputs. It because if the loss of this matter

11:19 information coming from that digit results in reorganization of these maps, and this

11:27 is now permanent with a permanent loss this digit. But this reorganization and

11:36 primaries amount of sensor cortex happens all time, and it is a dynamic

11:44 . It is a dynamic map, like the activity in the periphery is

11:50 . And this bottom example, you a digit to and digit three that

11:58 being repeatedly stimulated by the spinning So those two digits are constantly being

12:09 systematic sensations disproportionately compared to the other digits. And when you look in

12:17 map off the monkey following this experimental up now what you're seeing is that

12:24 areas of the brain that are dedicated digits two and three have enlarged significantly

12:35 reorganize themselves. And this critical map that is the area that is responsive

12:42 digit three and digit to is compared two digit for digit one

12:52 That means that repeated activation of these digits reorganizes the primaries a matter,

13:00 cortical map into having basically, these to and digit three cortical activity that

13:10 increased. And this is all not Lee just cortical activity. This is

13:17 synaptic plasticity. This is also formation the new synapses. So the more

13:21 stimulating digit two digit three you for synapses that communicate that information all the

13:28 into the primary somatic sensory cortex and inputs that are coming from digit 23

13:34 strengthened and the maps at the level the cortex are enlarged at an expense

13:41 other fingers that are not as So now think about what happens every

13:49 to your cell phones, and what are you using? This will tell

13:56 about the fact again that the brain's plastic that the cortical maps can get

14:04 and reorganized that we can, image activity in this cortical maps.

14:16 then we can image this activity using techniques. So think about the phone

14:27 again. I mentioned that at the , in the course off the

14:31 think about the actions that one had take to make a phone call 20

14:42 ago. Think about actions that one to take to find out the latest

14:53 30 years ago. You have to to a newsstand, pick up a

14:59 or go to the library and shake a newspaper. If you wanted to

15:03 something from archives, you want to library, and you requested something that

15:07 called microfiche, almost like a So my new things that were tiny

15:15 of all of the journals, newspapers, mostly this was your

15:20 and then what you would do with paper. You would pick it up

15:24 you unfolded, Read a page and . Read a page. How do

15:28 read news? Now? First of , you look at the news on

15:32 TV most of the time, and you read news, it's on the

15:35 . And how do you read news one finger? This hand is

15:39 or the hand that is holding is the phone, and your main hand

15:44 just tapping one or two fingers. think about your maps and actually imbalance

15:51 you would see in these maps where whole Palmer grip is represented much stronger

15:57 on the control lateral side and on left side. Because I'm a right

16:02 individuals so would have a lot mawr a lot more cortical space that's dedicated

16:08 the maps of these digits. that are active on this hand.

16:15 this is an example of all of sonata sensor information. Uh, that

16:24 into the somatic sensory cortex. if you're listening to more music than

16:31 census, auditory senses are potentially It is also quite common that if

16:38 doesn't have very good vision. They . I'm or on their hearing,

16:42 the hearing might be more sensitive than person that has good vision. There

16:47 a limited amount of space in the , so if you are exercising certain

16:54 , if you're activating certain synapses having Auditory visual, sonata sensory Um,

17:05 obviously there's there's there's a complexity in brain networks. They choose what information

17:13 pay more attention to. If we in the dark world, our readiness

17:19 be developed differently. Um, if lived in the world of some of

17:24 insects or bees, we would be in the thermal map world. That

17:29 we would perceive all of the surrounding not as we do as humans,

17:34 rather as hot spots off thermal So that iss what we have,

17:45 we constantly evolve because technology surround us , and because of that, our

17:56 change our brain maps change, our maps evolve, and it's a beautiful

18:06 of life that we all go through is in the brain and prefers very

18:12 its lending itself to learning but can be injured and can also be hijacked

18:20 neurological disorders. and abnormal brain So I'm gonna pause the recording

18:28 So let me remind you hear of visual system. If you recall,

18:31 had the maps of activity and we the maps in this case, the

18:36 dominance columns that where the columns or areas of the brain that were dominated

18:42 one eye over the other eye. we just basically with this, continue

18:48 about brain maps in the New York . Remember this. The structure of

18:53 layer structure off the columns of the columns, small columns of process information

18:59 are linked to the hyper columns. so when we came up, for

19:04 , and looked at the orientation columns , Okay, we said that if

19:11 look at these cortical these air cortical cortical maps Mhm Um, it's very

19:20 because you have orientation columns where cells a particular area of this column,

19:25 responsive to a bar of light a specific orientation. And so how would

19:31 do an experiment like this where you visualized these orientation columns? How can

19:37 visualize all of these individual cells, and yellow? Reacting to one direction

19:42 light orientation of light bar cells and reacting to another orientation of light bar

19:50 mentioned in the past that there is technique that's called voltage sensitive dye image

19:55 technique and this is what I'm about share with you. How is this

20:02 ? And what? How can you activity in the cortex like this?

20:07 how can you pick up activity from different parts of the brain? And

20:12 when you talk about voltage sensitive these air very interesting dies. And

20:19 are the guys that I have worked my laboratory here at the University of

20:23 as well. And what you see on the far upper right corner is

20:30 see, essentially a protein channel that be conducting ions across. Okay,

20:36 these air our channel conductors that are a plasma membrane. What you're looking

20:41 is a cartoon of the plasma membrane you see these little squiggly warms.

20:47 , these little squiggly warms our little molecules, and these little dye molecules

20:54 embed themselves in the fossil lipid bi . And as the current passes,

21:01 the current dip polarize us, is positive current comes in the South,

21:06 see dies that will change their These warms will change their confirmation.

21:15 well, this confirmation will be reflected the fluorescence properties. Most of these

21:22 are fluorescents and the fluorescence property. with deep polarization you'll have an increase

21:28 in in dia activity and with deep . A lot of times you will

21:32 able thio High levels of activity would these red hotspots and low levels of

21:39 or hyper polarization would represent the blue here. And so in the for

21:46 . For the neuroscientists to visualize these activity during visual tasks during visual stimulation

21:55 and to visualize these orientation columns and these columns they're made. This is

22:00 experiment that was actually done because you to open up the skull. The

22:06 day tripper nation have to very carefully up the skull and expose through the

22:13 and through the dura mater, the you have to cut through the meninges

22:20 expose the surface of the brain. , so this is an experimental

22:25 But you might imagine that without bolted guy, a similar kind of setting

22:32 is used to identify the folks side areas in the brain that are generating

22:39 activity, uh, in humans. before neurosurgical activity. Now, this

22:44 an experimental set up, but you do that Experimental set up concurrently,

22:50 can embed an electrode which records the and potential, and you can place

22:57 fast camera. It has to be fast camera processing, 10 kilohertz or

23:05 kilohertz, at least 2000 frames per . That fast camera is mounted on

23:11 of the microscope. So this microscope focused on is looking in this window

23:18 , and you have fast camera and animal's head is mounted and the animal

23:22 being presented visual information. And that camera is connected to the computer and

23:29 computer does is that the changes in fluorescence properties and these vaulted sensitive dies

23:36 reflected and translated into digital change that recorded in the computer. And so

23:43 , you have these voltages sensitive which are fluorescent dyes, and you

23:49 use a microscope or you can use macroscopic in this case. So you

23:54 still be, uh, um enhancing signal some five or 10 times.

24:01 four x or 10 x So it's but its macro because you have to

24:07 a large window. You're not focusing on a single cell. So you're

24:11 a large window. View this with microscope while you're doing the experiment.

24:16 as you present animal with a visual , voltage sensitive dies which are present

24:22 the cortex. So you apply voltage dies onto the cortex that you're going

24:27 image these voltage sensitive dies absorbed themselves the membranes of the neuron.

24:34 And as you stimulate the eyes, reckless of the animal left and right

24:42 or orientation of the signal in one over orientation of the bar, light

24:48 bar, one direction over the What you're doing is you're changing the

24:54 potential, and the changes in the potential are translated into these cortical activity

25:01 . And these cortical activity maps represent changes off the voltage sensitive dye

25:07 Confirmation all properties as the current flows the channels, is to sell

25:11 polarizes some hyper polarizes. So this how these experiments were done. And

25:17 gonna post this article on bolted sensitive image ing. It's a mostly experimental

25:24 of imaging. Andi, Uh, , for example. Window could also

25:31 used for intrinsic optical signal images, unfortunately, won't have that much time

25:36 go over and look at it. , I'd like to share a video

25:41 was done by my graduate student and and my laboratory in voltage sensitive dye

25:48 ing in one second. So the that we did with a new

25:54 my graduate student Ah, lot of had to do with How do seizures

26:01 in the brain, where the mechanisms lead to the formation of the

26:07 where do this seizures originate? And do they travel across different cortical

26:15 What are the dynamics of these The idea was not only to understand

26:20 mechanisms and the dynamics of the seizures them to come up with alternative,

26:25 and un explored ways of controlling these neurological activities. The name of this

26:33 epileptic brain waves, and this was a part of the competition that University

26:38 Houston organized from 10 years ago in ing of scientific activity. And so

26:45 new bomb, uh, managed thio a third prize for basically representing science

26:53 this visualization or, in a artistic visualization. Off science, the

28:23 , so let me explain to you happening a little bit here. So

28:27 is called the stimulation or paired stimulation the hippocampal tissue. This is a

28:35 off the brain. It has a structure. This is called the dente

28:40 to see three area and the sea one area, this black stick.

28:45 here is a stimulating electrode, and slice that is sitting here is a

28:51 of the hippocampus that has been taken a rat brain, and the slice

28:56 been impregnated with voltage sensitive dye. now those little squiggly, warm,

29:01 sensitive dye molecules air sitting inside the of penetrated into the plasma neuronal membranes

29:08 the neuronal membranes, Uh, And as they stimulate as we stimulate

29:14 a stimulating electrode, we see a flow of activity. And so,

29:19 we stimulated with the normal with a solution or normal brain, you see

29:28 levels of activity that's green, and pretty well organized, and it's pretty

29:33 confined. And then, in the image ing, we now induced an

29:41 condition. And so this slices now and the same stimulus, the same

29:48 of stimulus, the same parameters now these massive mountains, as you can

29:57 . And they're quite disorganized, their specific. And even after the

30:03 there is a significant level of activity remains so. This is basically this

30:08 normal activity and normal hippocampus here. this is a bill epic activity.

30:14 this is a bill epic activity mapping hippocampus. So let's watch it

30:18 In this audio visual representation of this thing, That way you can see

31:02 math is now disorganized. Now, is a electric activity. A zit

31:08 produced spontaneously, meaning that there is stimulating. Electra is the structure of

31:14 brain in the scythe when David Byrne and in the in the hippocampus.

31:30 now we're gonna image in the primary cortex, okay? And please pay

31:36 to this. This here where you the block is the surface. The

31:42 is a superficial new cortical layers. this is layer one, and all

31:46 way. Here is layers 56 where see this gray boundary here that's already

31:52 cortical So this is layer six all way to layer one. And this

31:57 primary visual cortex. And what we're here in this experiment is epileptic activity

32:04 forms of its own in this epileptic . And I have a recording electorate

32:10 it's sitting here and recording electrical activity like I showed you in the experiment

32:14 the monkey brains. So the electorate embedded here, and it's picking up

32:19 activity so that we can match individual activity. Ah, local neuronal network

32:25 with the overall view of what's happening this cortex. And so this is

32:30 huge advantage. Well, you can plant 12 electors, maybe four or

32:35 , maybe eight if you drive yourself across this cortex, and so you

32:39 pick up a different points of recording ing techniques such as vaulted sensitive damaging

32:45 . Where one of these peaks represents from about two or three cells allow

32:50 to visualize across large spaces of the . Yes, there is a large

32:56 , even that window that's open on monkey brain. That's few centimeters,

33:00 a couple of inches wide is a window, and so This is what

33:07 sensitive dye allow us not only recorded one point or two points, but

33:12 visualize how the six activity in neuronal is traveling. And you will see

33:18 very classical activity coming from lower levels up the ladder to three.

33:24 you have a lot of lateral projections are intra cortical, and then you'll

33:28 this activity goes back into column like and dies down again. And so

33:34 give you a mass interpretation of a right here with a layers The O

33:52 o. I think this is the map edge Analysis of the way can

34:10 E. There are these very fast in helper in the brain and you

34:36 see these waves of red and blue blue, red and blue drivers and

34:40 the blade through the brain, The trouble. You wanna hear a funny

34:49 ? So we did these experiments and let like half of the world know

34:54 we're picking up fast ripples of activity are very fast or 400 hertz oscillations

35:00 can happen in the brain now. just happy about it that I recorded

35:05 fast oscillations and the brain tissue like going on? I have this

35:10 Cameron was, I think, 9 . Nobody in Houston had the fast

35:16 fast on the camera from both the of damaging as I did. Nobody

35:19 do it like this. My we were so happy were the first

35:25 . And then we figured out that is an artifact. Ha,

35:29 Yes, indeed. We spend months months working on an artifact, and

35:34 know what these air these air surface . But it's a real thing because

35:38 said, Well, how is this way? What is this? We're

35:41 changing anything, but we're getting these . But we did change something.

35:46 put a chemical in the solution and chemical in the solution. Change the

35:51 attention. And as that water tension the surface changed, it also changed

35:56 influence the reflective properties off the tissue , which was really not representative of

36:03 tissue underneath the broader at the And so it's really great lesson that

36:09 can spend time starting an artifact, in the end, it's something that

36:13 extremely interesting for physicists and people that water attention and fluid dynamics is

36:19 because these are very fast fluid dynamics the 400 Hertz, we're,

36:27 Perper for a second. Moving in fun. Things like that chaotic orchestra

36:42 ripples of apple app remain. wait here on the way.

37:05 Okay, okay. Stop for a . Think about this. You're listening

37:14 music. You're getting somatic sensation coming your ears. Wow. Sorry.

37:21 sensation. You can pleasure here, in auditory sound, the sound is

37:26 into your here. You have a map. You have a sound

37:30 right? What if that frequency What if that sound map look like

37:35 ? So the music that you're actually to think about that. What if

37:39 music is actually encoded as a That this professor showing me now that's

37:45 you should think about. This is visual map. It could be an

37:48 map. It's your thought map. that's happening in your cortex. Communication

37:54 these networks, these complex waves of e all my nominees and that led

38:08 nation in style to the job in report. Whoa ! Spooky. All

38:45 , so that was really

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