And first, at first I want to remind you what we finished last class which was on Tuesday. So we had a discussion of the general structure of the cerebrum, right? So we have two hemispheres. Okay, hemispheres are separated by the median longitudinal fissure.
separated from cerebellum by the transverse. Cerebral fissure, there are elevations on the surface of the cerebrum that are called gyri, and crevices between those elevations are called sulci. cerebrum can be divided each hemisphere can be divided in into five lobes okay frontal occipital parietal temporal and the lobe called insula it's located deep to those four superficial lobes cerebrum has three major parts functional parts and sort of for the future reference when we say functional parts they may not be clearly distinct in terms of anatomical separation for instance bones the human body are very distinct.
If I'm telling you that humerus and radius are two different anatomical structures, you can clearly see that. When I say functional parts, they may not be very strictly physically separated, but functionally they are very different. And those three parts are cortex, which is fairly thin, dark superficial layer of the brain you can see it here that dark beige layer on the surface sometimes this is what is called a gray matter of the brain okay cortex is responsible for our conscious activities either controlling skeletal muscles the motor activities or perceiving the information flow, the sensory input from the rest of the body and special senses.
Basal nuclei it's a deeper structure which is generally responsible for the movement control and we will discuss in some details what exactly it does. And you can see that there's a bunch of white matter which is responsible for communication between different parts of the cerebrum and more general communication between different parts of the central nervous system. Does that make sense?
We're going to discuss also the functional division of each part because cortex has different regions, basal nuclei has different, several anatomical parts, and white matter has three different types of fibers that comprise it. Now think about this for a second. We know a lot about the human brain, really a lot. We know what are the functions of different parts of the human brain. We know where, say, I don't know, parts of the brain that control, that receive visual information are located.
Parts of the brain that are responsible for motor control. We even know what are the functions of the brain structures that have no conscious control over them, like cerebellum or basal nuclei or brain stem. We still know what's going on there. So what do you think, how do you think we started to gain this knowledge? How did we start to gain the knowledge about the functions of the brain?
What is the easiest way to know, to learn, what is the function of a specific structure in the body in general? Exactly, cut it off. Not deliberately, I mean, some people did that deliberately. There was a famous Dr. Mengele. You may have heard an argument that he was a famous Nazi doctor who was conducting experiments on the prisoners of war in concentration camps.
And there are claims that he gained some really important physiological information about the human body. despite the fact that it was extremely inhumane. I have to disappoint you that he did not do his experiments in a very scientific manner, so the value of his quote-unquote research for the science is limited because of that lack of proper controls.
Yeah, he had something like, do they have the same psychological profiles or something? Yeah, he was doing that. He was, they had really, if you're into that, you may also read about the Japanese, something like a Squad 731, I will check during the break.
Japanese fellas, they actually... were far ahead of Germans in terms of the anti-humanity and cruelty, but they were looking mostly at the effects of anesthesia or lack thereof and infectious diseases. They were studying effects of infectious diseases on humans.
Again, those fellows didn't really do any proper controls, so it was kind of a problem. What was the name of the person? Dr. Mengele. M-E-N-G-E-L-E. Interestingly enough, he wasn't...
As far as I know, he wasn't caught after the... Yes? There's like a conspiracy that he ran away to Brazil.
Argentina, I'm sorry. Yes. Argentina. That's where all German people went.
Yes. That's why there's like a weird number of... And like a specific...
Well, there's Twinsburg here, come on, and Dr. Mengele wasn't ever in the United States. It may also be environmental, by the way. Yeah, it may be.
No, it's just one of the... the hypothesis is that birth of twins is sort of a protective mechanism when women are exposed to the stressful conditions, whether those are chemically stressful conditions or psychologically stressful conditions, sort of to protect, to... and we're talking about fraternal to... Secondary oocytes are released during ovulation, and when they are fertilized, you get two fraternal twins.
Sort of, okay, let's bring them out faster. Let's not wait for the second opportunity. Okay? I mean, it's a high... hypothesis, nobody would ever be able to prove it.
So loss of function, right? With the brain it was mostly study of people who suffered the brain trauma or stroke. Initially it was brain trauma because, you know, with the stroke at the time, like in the 19th century, it was impossible to diagnose which part of the brain was affected by the stroke.
Eventually, when we got the imaging techniques, even such an X-ray or then CT, it became easier to check this. Now, another interesting approach that is less invasive, to say the least, and... much more benign and allows you to gain way more information is functional MRI.
So magnetic resonance technique allows you to measure the changes in the body in the real time, especially it allows you to change the blood flow to the certain regions of the brain. So if you would say have somebody speaking, or hearing, auditory cortex, you will see that, so if we have a conversation and we have a conversation, these areas of the brain are activated and you can see increased blood flow. If you would expose someone who's watching a movie to the functional MRI, you would see increased amount of blood flow.
to the occipital portion of the brain because that's where the visual perception parts are. Does that make sense? So and you don't, MRI is not damaging to the tissues at all. So person doesn't even feel what's going on the only as far as I know the only requirement is to sit still. believe because of the price oh you mean no overall it MRI was the latest that was developed that make sense oh when you get diagnosed probably the price I would say that's the only that's the only issue MRI machine is costly and they have to get the money back so they charge a load okay and in some cases they don't even bother going to ultrasound if they understand that MRI is going to get better picture in some in some cases of brain trauma something like that so we're going to talk about cortices okay and here you see the empty spaces When you see the empty space, I suggest, you know, you kind of feel it out.
Or you can just write down, if you take notes in your lab notebook, that's fine, you can just write it down. Okay? But sort of to keep you from falling asleep. So motor cortices.
They are highlighted here in red. As you can imagine, all motor cortices are responsible for the conscious control of movements. Primary motor cortex, which is located at the posterior portion of the frontal lobe, directly controls the motor cortex. voluntary movements, skeletal muscles, so-called pyramidal or corticospinal tracts.
Now if you think about the name corticospinal tracts in the spinal cord, they transmit the signal from the brain, from the motor cortex to the skeletal muscles sending the impulse that directly you know causes the constriction, contraction of the skeletal muscle. Does that make sense? So it's direct control. So what if there is a damage to the primary motor cortex?
What's going to happen? Come on, say it out loud. What's going to happen? How is it going to be manifested?
Yes. I probably didn't explain it well so think about this primary motor cortex you're going in the right direction but it's a little bit more severe right yes you have no control of the muscle so the part of the brain this part of the brain sends signals to the muscles does that make sense So damage to primary motor cortex means paralysis of a certain muscle or group of muscles. For instance, in the case of the stroke, if the primary motor cortex on the left side is affected, then right side will be paralyzed.
It depends on which part of the motor cortex is damaged, but right side will be paralyzed. And we'll talk about lateralization. Yes?
To some extent, yes, but not completely. You can train the person, and it depends on the degree of the damage. We'll talk about...
For example, if you have a part of the motor cortex that controls leg movements, and say more specifically ankle movements damaged, then you can train your brain. You can reestablish some links so that adjacent parts can take over. but it's not going to be it's not going to be as precise as it used to be does that make sense movements are going to be sloppy because you don't have same innervation of that area yes you can and of course if we talk about the massive damage that involves regions that control all muscle in the leg then you boned okay there's no way your leg is going to move Maybe just a little, but no way you can be able to walk. Okay?
Sorry. Now, premotor cortex is an interesting structure. It controls primary motor cortex.
Okay? So here's what happens. Premotor cortex is sort of a medium command center.
So it collects the sensory inputs. from different parts of the brain, sensory cortices. And it also receives the control inputs, motor control inputs, from basal nuclei and cerebellum. And then based on the collected information, so sensory inputs and control inputs from basal nuclei and cerebellum, premotor cortex plans the movement.
Does that make sense? Now let me explain. If you, I don't know, I'm trying to think.
If you play sports, any sort, say basketball, when you are shooting the ball and you stand, you do one thing, one sort of movement. Does that make sense? When you dribble the ball and you have to shoot just from get-go, it's going to be slightly different movement.
When you are, I don't know, tripping over, falling down, trying to shoot, it's going to be third kind of movement. In every case, premotor cortex receives information first about your balance from the vestibular system. if somebody guards you about this person guarding you okay visual input about your body position in space whether you trip in or not and on top of that basal nuclei and cerebellum send control impulses which you are absolutely unaware of, consciously unaware. So they automatically control, they refine the movements, make them more precise.
And premotor cortex integrates all those inputs, both control inputs from cerebellum and basal nuclei, and sensory inputs from different parts of the cortex to plan the movement in the best way. Does that make sense? So it...
plans the skilled movement so how do you think the damage to the premotor cortex will manifest go ahead can you generalize will you be able to contract a muscle still yes if you trained this skill you wouldn't be able to repeat this skill. Does that make sense? So you see you're losing skill.
You don't lose the ability, say somebody's punching you you, what do you call it, like avoid it, right? You weave away. So you used to be able to do that.
You cannot do that anymore because you don't have that movement. Okay? Can you relearn this skill?
With time. You can. If not the entire thing is gone, then other parts of premotor cortex eventually can take over.
Does that make sense? So one of the, in my opinion, best examples... You used to play piano, then you suffer trauma or stroke, and you realize you can move your fingers, but you cannot play piano.
You lost the skill of playing piano, you lost that mechanical skill. You can relearn that with time. Does that make sense?
So it's planning movements. You cannot plan that movement, playing. You cannot...
plan that movement. Does that make sense? Okay.
Now Broca's area, you can see it right here, it's a special area that controls muscles involved in speech. You have to understand this is entirely the ability to say things, ability to control muscles that are involved in speech, muscles of your throat, muscles of your tongue, muscles of your lips, muscles of your face. Does that make sense?
So what if parts of the Broca's area are damaged? What if the stroke is in this area? Go ahead. Slurred speech or lack of it.
Can you still write things? Sure, yeah, you still have language. You just cannot say anything. Right? Does that make sense?
And finally, frontal eye field. Control eye movements. Well, that's kind of obvious. it's damaged, then you cannot move your eyes and focus them, well, point them at the object that you want to see. That's pretty simple, right?
Now, since we are starting that discussion of different cortical areas, I'm going to give you the idea of what I can ask you. The question can be about the function. That makes sense? Those are slightly different muscles. Swallowing involves some involuntary control and swallowing is swallowing reflex is controlled by medulla.
Does that make sense? So different types of controls involved you will be able to swallow because all you need to do is to push the food with the tongue then everything else goes absolutely it's a reflex does that make sense so you start swallowing voluntarily but what goes then is not voluntary go ahead the brook is the brook is area yes there's only for stupidity but it's not about it's not about like how you can still think okay yeah you can still have the result that come up and you're at the worst they'll they'll start they'll try and say like can you hand me that but then they'll start talking about like the Elephant in the garden. Yes, that's the difference. That's the difference. That's the comprehension of language.
That's the different part of the cortex. Does that make sense? Yes. Awesome.
So, type of question. Damage to this area will cause such and such. You pick which area I'm talking about.
Okay? Such and such part of the cortex controls. The following. I'm telling you. Wernicke's area controls.
You've got four answers. You pick one. What it controls. That make sense?
That's number one. Know the function. I put it in the table so it's easier for you. More structural.
Okay? Second thing that I will ask. Where something is located.
Do you understand? Frontal lobe, temporal lobe, parietal lobe, occipital lobe, insular lobe. We good? Is that understood? Awesome.
Now we're going to talk about sensory cortices and I really like that conversation because it's interesting and there's a lot of similarities between sensory cortices. So first is primary somatosensory. Actually both sensory cortices. primary and association are located on pre-etal lobe.
So the primary somatosensory cortex, soma, what does that mean? Can anyone remind you? Body, right?
You don't have to raise your hand, just yell from the place. Yes, it's a body. So somatosensory Cortex, primary somatosensory cortex receives sensory inputs from the body. What types of sensory inputs we are talking about here?
What can you think of from the body? Okay, position of the body in space. Yes. If you close your eyes, do you know if your arm is elevated, do you know if you like squatting?
If you close your eyes. That's position in space. What else? Touch, pain. What else?
Sagan? No, that's a separate one. That's a special sense. Does that make sense? No pun intended.
What else? Come on. Special sense.
Just one, another modality of sensation. So you have pain. you have touch touch generally any sort of mechanical okay can be touched can be pressure it's also touch vibration but another modality temperature okay so those are kind of major ones right and you know extreme temperature can cause pain extreme touch can cause pain okay and you have to understand somatic sensations aren't only coming from your skin or that's pretty much where most of the sensory receptors are but also from the inside of the body joints muscles that make sense think about it if you if say I look at you I'm bending my knee now trust me okay I know that my knees bent I don't see it but I know it because I know that some of the muscles are contracting and there are kinesthetic receptors in the joint and whatnot.
That make sense? So the function of primary somatosensory cortex is to receive the info and do a little bit of this spatial discrimination. Okay?
Where the sensation is. We're clear what the spatial discrimination is. Now, the function of somatosensory association cortex is to integrate somatosensory information.
All right, does that make sense? No? No?
So we put it all together, okay? Say, I don't know. If you have, when we were kids, we loved to play the game.
One person gets blindfolded and this person walks around the room and catches other people and tries to identify, you know, who's been caught by touching the face. You better play it in a really crowded room with a lot of furniture because the most hilarious part is when this person hits like a door or something else. It's really, really funny.
So, but think about this. You touch somebody's face, you can tell sometimes who that is. Does that make sense? You reach in your pocket and you need to try your car keys, find your car keys.
You don't need to look at them. you can just you know touch them and okay that's my car key that's not the key from my house or something does that make sense so consequently the damage to the association cortex will deprive you from the ability to do such discrimination so i wouldn't be able to say you know i'm looking away and i'm i'm touching oh that's the faucet okay because the shape kind of matches i wouldn't be able to do that i will need to look at it Okay? Make sense? And obviously damage to the primary somatosensory cortex will deprive you of this sensation. You wouldn't be able to sense, to feel things from a certain part of the body.
Okay? Are we clear on that? Priatal lobe sensations, integration of body sensations. Both somatosensory and motor cortices exhibit so-called... somatotopy.
So soma means body, topi, topos means space. What does it mean? It means that whether we're talking about motor cortex or somatosensory cortex, each part of the body is represented. the brain in the cortex as the certain area let's look at the motor somatotopy first it's shown here in the left bottom corner and it's on the left is highlighted in red you see that what does that mean it means that this part for instance of the cortex controls muscles of the shoulder and muscles of the trunk.
Okay? This part, fingers and thumb, this part controls tongue. Does that make sense? Now, if you would look at it, what you're going to see is that some muscles, get more control, sorry, some muscles, some regions of the body are represented by a larger area than others.
Okay, let me explain. Your legs are pretty big compared to your face. Make sense? They're really big.
Seriously. Okay? region that controls the movements of your leg is pretty much here.
It's rather small. Now, relatively small face is controlled by the region of the motor cortex that is like twice as big as the region controlling the leg. You see the difference? Can you see the difference? Which consequences does it have in terms of the motor control?
Can you specify, what do you mean by more? I'm trying to get the word out of you and the word is precision. Does that make sense? So if I look at the region that controls fingers, it's huge. It's the same as for leg.
You can do really nice ways like you can play violin with your fingers. Or you can do the surgery with your fingers on your arms. Try to do that with your legs. It's going to be really sloppy. I mean, people learn.
Don't get me wrong. People learn. Some people learn to ride a bicycle using their legs. There was some ridiculous story. A girl was born without legs, without arms, just birth defect.
She rides a bike. She can drive like a kid's car with her legs. People learn that. Okay?
So that's possible, but the more cortical area is related to a certain part of the body, the better control it's going to have, more precise control. Does that make sense to you? Another thing, regions that are anatomically closer to each other, the regions that control them in the cortex will be located closer to each other as well.
So say this entire part of the cortex controls arms. You see that? Okay. This entire part controls face.
Of course, it's not like this exact point controls, I don't know, buccinator muscle in your cheek. There are adjacent patches in the cortex that control buccinator. So if one gets damaged, you may not lose control of a certain part of your body entirely.
It may be sloppy, but not entirely. So like, who are class disasters? And like, you guys are seeing the need to see just what they know, how the outcomes are that control some of their body movements? Great question.
I don't think that there will be. OK. So your question, let me reiterate because I need to get my thoughts together. Your question is whether are any differences in terms of the brain structure, the cortical structure between world class athletes.
say dancers or piano players or I don't know anything else very skilled and regular folks. I don't know about the studies I'm not saying that they weren't done but from my perspective you would at least see differences in the synaptic strength how well and fast the signal is transmitted between the neurons. you may see increased number of synapses in general. And if those people started to learn the skill from, I don't know, three years of age, then most likely there are going to be anatomical differences.
There were studies, inadvertent studies, not deliberate studies. You know, some people grew up in conditions with very low social interaction. People who were raised by animals.
It's not it's not a fairy tale. There were people who were raised by dogs and you know monkeys and whatnot Oh yeah, well those guys should have been stupid because Here's the thing people who were deprived of normal human social interaction had less gyri and solci in the brain So the brain was less folded. And what is the function of those folds? To increase surface area, which means increasing surface of which part of the brain? Superficial one.
Cortex, which contains what? Yeah, conscious activities, okay, thinking and all that kind of stuff. Does that make sense?
So they were deprived and they were not as intellectually capable and would never be because they don't have enough neurons in the first place. Make sense? Okay. Sensory somatotopy.
That's also very interesting. Look at the right here. Okay. you see that also every region of the body has a matching region in the somatosensory cortex that receives the info from that part of the body. Does that make sense?
Like this part receives information from your hand and fingers, this part from your face. Do you see some similarities to motor cortex? size wise. If you would look at the size of the sensory cortex that receives info from say knee and foot It's not that big hand and especially face is pretty huge What do you think it means? somatosensory yeah well I mean I'm kind of giving you hint we talked about sensations so what would be the profound difference between face and the best example actually is the trunk okay so that's the trunk that's the face it's gonna be the most profound difference in terms of sensations between the face and the trunk Yes, the face is more sensitive.
And there is a test called spatial recognition test or two pin test. Take two pins, put them on different parts of the skin, different areas of the skin and start to get them closer to each other. At a certain distance, you won't be able to distinguish between them. Does that make sense?
On the face, you can get very, very close. A few millimeters. Before you won't be able to tell apart the pins that touch your face. Does that make sense?
On your back, it's like a few centimeters. And you stop distinguishing it. You know? When we were kids we had a game, also we had a lot of stupid games now, I realize when we were kids.
You close your eyes and somebody starts to move the finger towards your elbow. And you tell this person to stop when the finger reaches the elbow. It's really hard to get all the way, because when you don't see it, the spatial discrimination on your entire brachial region isn't that good.
Usually, you know, you manage to get it like all the way down here. and they say oh yeah that's the elbow no that's not so it shows you that special discrimination okay ability this sensitivity of a certain body area depends on the area of somatosensory cortex that this body area sends the information to and in addition to that if you think about it you have much more sensory receptors on your face or on your fingers, than say on the back of your trunk. Does that make sense? It's all about sensory receptors.
If you have high density of sensory receptors, you gotta have more cortex that will receive info from them. Does it make sense to you? Okay. Now, other... I have no idea what happened here.
Okay, awesome. Cortices of the special senses. Visual.
Primary and association as well. They both are located on the occipital lobe of the brain. Primary visual cortex. Receives the information from the retina. It does a little bit of the, how to say, a little bit of integration, not so much.
Mostly like contrast of the image. movement and then the sensory inputs are integrated in the visual association cortex. So that's where most interpretation occurs.
So it's responsible not only for recognition of things like color or the form of the object, but it also allows you to distinguish between people's faces. It's a known condition. I don't... something agnosia. There is a condition in which people cannot distinguish people's faces.
So this person will meet you in the hallway. and you introduce yourself and say oh nice to see you blah blah blah you will have a conversation and then this person will meet you in the hallway 20 minutes later and they will not even greet you because they don't know you they don't recognize you it is a damage to the visual association cortex that make sense auditory. Now auditory cortices are located in the temporal region of the brain.
You can see them right here. They are responsible for your hearing capacities. Primary will just receive impulses and will be responsible for distinguishing sounds based on pitch, loudness and location. When we'll get to special senses, we will see how it works. Okay, it's pretty simple.
Pretty much the pitch. Now, I'm not going to go into the pitch recognition. I know how it is, but it just takes too long.
Loudness, frequency of action potentials. The more frequent action potentials are, the louder the sound you perceive. Make sense? But then association auditory cortex will allow you to interpret the sound.
You hear something and you say, oh, that's the thunder, oh, that's the cat meowing, or somebody is speaking and I know that person. Moreover, you will be able to recognize the melody and remember the melody. Oh, it's something I've heard before.
Does that make sense? Actually pretty good with sound, like second best after dolphins, really good. Olfactory cortex, also in temporal, okay you can see that uncas here, part of the olfactory cortex. Smell, we are inferior.
to many animals, for instance, animals like snakes, lizards. Actually, if you happen to be on the main campus in one of the biology classrooms, Professor Rosemeyer keeps a lizard, Tegu, and he has really poor vision. Smell sensations are absolutely tremendous.
You can put him on the floor and roll the grapes in front of him, and he will just go to the grapes because he can smell them. He's really good at smell. Same goes for snakes. Dogs, of course, but we're pretty good.
If you don't compare us, pretty good. Yeah, I mean, we can recognize. about 10,000 different scents.
We can distinguish between them. Okay? I think it's decent. And we have decent sensitivity. The thing about olfaction is that it is very tightly connected to unconscious responses to.
Does that make sense? Think about this. Sometimes you smell something and you think it's unpleasant you don't know why it's just unpleasant right there are examples of smells that will cause for instance choking or vomiting and you won't be able to control it it's a physiological response to a smell it is often referred to as rhinencephalon olfactory cortex because it involves multiple parts of the brain okay for instance amygdala its main function is the fear response hippocampus its main function is the memory I don't know if you have lived through that but sometimes you know you you get somewhere and you smell things and it Immediately you know causes some memories to pop up We lived in on Midwest we lived in Nebraska for a year then moved to Louisiana these two states smell totally different Okay We come to Ohio in the summer we get out of the plane. It smells like Nebraska Midwest smells different than the south probably because of vegetation but and it immediately you know we smelled it oh that's nebraska remember that okay it's unconscious we didn't even try to remember right a lot of it is emotional response and physiological for instance limbic system is the big part of emotional responses to any kind of stimulus including olfactory does that make sense gustatory, taste, sensation and recognition both, and physiological responses of course, you know, you don't like some taste, you like others, okay, and finally visceral sensory cortex.
Perceive signals from internal organs. What kinds of signals? What do you think?
Remember, that's conscious perception. What can you consciously feel from internal organs? Hunger actually is in hypothalamus, really.
When you eat a lot. what does it feel? You feel full, stretch. It's mostly stretch actually.
Sometimes pain because of ischemia, like if the blood flow stops to go to certain organ, feel ischemia. Like when somebody has cholecystitis, inflammation and stretch of the gallbladder because of the gallstones, again it's stretch. Does that make sense? So visceral responsible for the sensations from the internal organs. Did you get it?
Good? Yes? Yes?
Uh-huh. It's not particles. You asking mechanism? Is smell still related to muscle detection? No.
Smell is entirely molecular interaction. It's a chemical that interacts with its receptor. We'll talk about it.
The mechanism of smell sensation is absolutely fascinating. And Linda Buck and that other guy are so wonderful. one of the best t-shirts i saw on one concert that effing guy so linda buck and that effing guy they got noble prize for the smell society discovery of the mechanism how we send smell and it's simple and elegant really okay so we got motor cortices covered we got sensory cortices covered but we never spoke about about like the thinking, the intellectual part of the brain. Multimodal association cortices are responsible for this higher intellectual functions.
The first that we need to mention is prefrontal cortex. Like this whole thing. Okay?
Here. That is what makes you, you. everything from intellect to the abilities to learn, to abilities to plan, the abilities to think in abstract terms, make judgments, make decisions, reason with other people. I mean everything, what we call thinking.
Does that make sense? So every time I teach AP1 I forget the name of the dude. He was a British docker. He worked in the docks. I don't remember his name.
No, I don't remember. Yeah, so what happened to the guy? He got the rod, yeah, going straight through his prefrontal cortex. Metal rod. Amazingly, he survived.
And they managed to pull it out. He didn't have any motor or sensory deprivations. Okay?
surprisingly I know you know sometimes things happen like that what happened is totally different thing his personality changed completely before the accident he was very mild-mannered quiet man after the accident he became aggressive irritable and hugely profane person like it was complete switch And in line to that, you may have heard the name lobotomy. That was a treatment at some point that was used to treat different psychological disorders, paranoia, psychosis, schizophrenia. The only, well, it's not the only problem with the treatment. But if you think about this. Surgeons were operating on the organ, which function they did not really know.
Let's be honest, we don't know a lot about brain now, too, compared to... I mean, we know some, but the part that we don't know is much bigger. That make sense? So they were doing that. And when I was talking...
Yeah, and... And... These... surgeries are changing people's personalities. It's a huge ethical problem, right?
You have John Smith. You do lobotomy on John Smith. And the person that comes out of the anesthesia after lobotomy is not John Smith anymore.
You really change, profoundly change personality. You don't just cure person from schizophrenia or paranoia. You make a different person. So lobotomy is banned, nobody's doing it anymore for these obvious reasons.
Okay? We'll try to do it differently. Huh?
I do not know the surgical technique really. I really don't know. Yeah, so I don't think it's really a great idea.
just in general. Now, posterior association cortex. It's located on several lobes, temporal, parietal, and occipital.
And the example, the great example is a Wernicke's area, which is located on the parts of parietal and temporal region. It involves many activities. recognition of faces, ability to locate yourself in space.
There are actually many structures that allow us to know where to go. Like when you're in the new city or in the city that you live, but you have to navigate yourself. There are many structures in the brain that are responsible for it.
Wernicke's area participates in speech recognition. You have to understand the difference between the Broca's area and the Wernicke's. What does Broca's area do? Muscles, muscles of the speech, okay? Wernicke's is the language, recognition.
So if there is a damage to Wernicke's area, I'm talking to you and you have no idea what I'm saying. Does that make sense? limbic temporal located pretty much here some of the structures I have shown you here like cingulate gyrus and parahippocampal gyrus, hippocampus and amygdala located approximately in this area. Limbic association area is responsible for emotions I want you to distinguish emotions from physiological response to emotions. Okay, think about this.
When you are relaxed and you drive on the highway and somebody cuts you off and you're relaxed, you may say, ah, whatever. Right? And just keep going. In this case, you have no...
your emotions, you calm, okay? There's no physiological response involved. On the other hand, you're rushing somewhere and somebody cuts you off and you have a road rage and you flip this person off and it all escalates very quickly. What's going to happen to you?
Your blood pressure is going to rise. Your heart rate is going to rise. You have massive release of cortisol in the blood and norepinephrine in the blood, okay?
And glucose and everything. Does that make sense? So that's your physiological response to emotions. But emotions themselves are controlled by the limbic association area. If you are afraid of something or not.
If you like something or not. And also, a lot of it is about... conscious control of the emotions. You know, like you, something sad happens and you think it wouldn't be good to cry now and although you're very sad and you know, you're very emotional and stable, you keep yourself from crying consciously.
Or you want to punch someone in the face, but you don't do that because it's not socially appropriate in this environment. Does that make sense? So you consciously, sometimes emotions overcome your conscious control.
You know that you shouldn't do it, but you do it anyway. Okay? Does that make sense?
A big part of the limbic system is the establishment of memories. Okay, and think about this. Emotions play a very important role in establishing a memory.
If experience is dull, you're probably not going to remember it. But if experience is very emotional, whether it's a positive or a negative emotion, You can remember it. I still remember things that happened like 22 years ago that were not emotionally dull in any instance. Okay.
So limbic system, that's why emotions help to develop memories. And the main structure that's responsible for the memory development and storage, hippocampus. Okay. That make sense about the association areas and stuff?
Now, lateralization of the cortical functions. Generally, well, first of all, sensory and motor controls are lateralized, which means your left hemisphere. exerts motor controls over the right side of the body and receives sensory information from the right side of the body and vice versa. Does that make sense?
Okay, that's one. Second, hemispheres control pretty much unique abilities. Okay?
For instance, you can see that the verbal memory, memory to, you know, Verses, texts, it's mostly left hemisphere. Shape memory, right hemisphere. Rational thought, left hemisphere. Non-rational, inverbal, intuitive, abstract thought, right hemisphere. language complication left musical ability right so usually the hemisphere that's dominant for language is considered to be a dominant but in most in most people it's a left hemisphere language math stuff like that so right-handed people usually have left dominant hemisphere, left-handed people usually have right dominant hemisphere.
That is why in right-handed people abilities, rational abilities, math are more pronounced. People who are left-handed more frequently engaged in artistic activities, you know, like music, painting and stuff like that. Does that make sense?
That is true. And some people who are ambidextrous, both hands work equally well. Hemispheres work bilaterally.
It's kind of cool. What's uncool is that there is a strong association between ambidextrosity and chances to develop... Mental sickness, yes.
Usually it's schizophrenia or any other sort of, you know, being bipolar and stuff like that. Okay? Yeah, yeah, it's pretty common. And another problem is that if you think about this, every time you try to reteach the person who's left-handed to become right-handed, you forcefully change the connections between the two hemispheres, and it may lead to some unwanted consequences.
It's a big stress for a person. A funny thing about teaching traps in hand... For some left handed people, you'll notice that if you teach them how to write with your right hand, they'll write... Sometimes there are many interesting things that can happen.
We have tweens in a family, and one of them is left-handed, one of them is right-handed. And left-handedness... may not be absolutely dominant. So the person may write with left hand, eat with right hand, play musical instruments with left hand.
That's what one of my kids does. So he has partial dominance. And his artistic capacities are absolutely horrible. So it's not necessarily true. white matter that's pretty simple remember we discussed so cortex is considered to be gray matter okay now white matter what is white in the brain which protein huh communication myelin sheath right so white matter actually consists of myelinated axons Those myelinated axons are bundled together in the tracts and the function of the white matter is to connect different parts of cerebrum with each other as well as connect cerebrum to other parts of the CNS.
There are three types. the white matter fibers first type is association fiber right association fibers connect different cortical regions within the same hemisphere does it make sense different cortical regions within the same hemisphere commissural fibers These connect same regions between hemispheres. Okay, so commissural fibers on this picture are showed in green. See what I'm saying?
Same regions, but between hemispheres. And finally, projection fibers, which is shown blue in this image. They connect brain stem or spinal cord lower levels of CNS to the cortex.
You can see them. They run sort of vertical from up to bottom and vice versa. And they first, some of these fibers, the projection fibers, they decussate, which means they cross over. The decussation point is in the medulla oblongata. And when they go into the brain, they form so-called corona radiata.
You can see that. That is called often internal capsule, a band of fibers, and then spans out to different cortical regions, forming corona radiata. Now, the largest... commissural fiber, a so-called corpus callosum. You have models on your tables.
If you separate the hemispheres, you will see the, I don't remember the latter, but it's a large, like a huge worm, the white bent structure. I don't have the model. It's one letter in the center.
It's right in the center. Can you see that? Can you try and point? Yeah, yeah, yeah.
Can you show it to everybody? Like the large white structure with one letter in the center. It's on top of the encephalon. It goes like this. Scorpus callosum.
Okay. which can be translated as Callow's body. Now, basal nuclei. When we talked about the different parts of this rib room, I mentioned that this part is not very clearly anatomically defined. It is anatomically defined, but not extremely clearly.
But functional, it's very different. So it consists of several parts. The caudate nucleus, the head and the tail of the caudate nucleus you can see here.
The putamen. And if you would look at the transverse section in the superior projection of the brain, you can see putamen, globus pallidus. a caudate nuclei here okay the function of the basal nuclei which pretty much surrounds the thalamus is the control of movements but this control of movements is not conscious what basal nuclei does it receives the inputs from the entire sensory cortex essentially basal nuclei knows what's going on. Does that make sense? Everything.
We talk about somatic sensations, visual sensations, auditory sensations, all kinds of sensations. Is that clear? It also receives the inputs from the cerebellum, which isn't shown on the image, but somewhere from here, from cerebellum. and function of cerebellum is movement planning.
So when basal nuclei receives the information about the environment from sensory cortex and the movements that are about to happen, it will exert its output to the premotor. cortex and that's important pre-motor what's the function of the pre-motor cortex pre-motor not the primary motor pre-motor planning conscious planning of movements that make sense what basal nuclei does it refines the planning okay it helps to start and stop the movements it inhibits movements that are excessive for unnecessary or antagonistic that make sense what is important first the activities of basal nuclei you cannot feel them when I'm playing piano I know the skill okay that's my conscious activity but the fact that I'm playing piano this way is partially because of the basal nuclei because it allows me to make those very precise very clean movements and obviously damage to the basal nuclei in any way or dysfunction of the basal nuclei leads to movement related diseases. Two great examples are Parkinson's which can be characterized as too little movement inability to produce full range motion versus Huntington's disease which can be characterized as too much movement. If you've ever seen patients with Huntington's disease, the first clinical sign of Huntington's is so-called chorea.
Chorea is a Greek word for dance. People with Huntington's disease cannot produce the proper, you know, uninhibited Properly inhibited movement. So they can't do like a precise movement. Movements are going to be excessive. Does that make sense?
Do I understand the idea of the function of basal nuclei? Again, no direct access to motor control. it works through the premotor cortex.
You see what I'm saying when I say no direct access to motor control? It doesn't send signals. Basal nuclei doesn't send signals to your muscles. Okay?
It sends signals to the premotor cortex. So if we try to picture it, it's going to be... basal nucleosin signals to premotor cortex and receives them from cerebellum, sensory cortices, prefrontal cortices, okay, and actually from premotor cortex as well.
Does that make sense? See that? Good. Not yet, not good yet.
Okay, let me see what's going next. Okay, so we're gonna take a break and when we'll come back...