The Cerebrum

hi everyone its mr. senti thanks for joining me today in this discussion that we're going to have on the cerebrum that's right the cerebrum what could be more complex what could be more important what could be more interesting and relevant than a discussion about the cerebrum and I hope I hope you find it interesting and enjoyable as well it's the largest part of the brain it's the most conspicuous you could see it right here it's it's the classic iconic view of the brain or cerebrum where most of the other structures apart from the cerebellum which is down over here posterior this is the frontal area here it's what most people think of when they think of the brain and there's a lot going on there and so I'm glad that you're able to join me in this conversation that we're going to have today so one of the things that I'm going to say right at the gate is that it controls all of our conscious thoughts and all of our perception of our senses and it dictates and commands and it tells our muscles to move and it is it houses all of our intellectual functions and so I I put this image here put on your thinking cap get ready for this video the shout out to to my students at the Community College of Vermont so glad that you're here joining me in this conversation that we're having on the cerebrum and so the cerebrum I just wanted to point out a couple of areas it and the in the top part right up here the top part of the cerebrum there's a place where there processes sensory information and that's right sensory information and so do you notice right here let me just be a little bit more clear there's a line that sort of separates right in here it's referred to as a central sulcus okay and I'll come back to this but over here just behind it right here is it is a somatosensory area and that's where senses are going to be processed and then just in front of it right here this is what's known as the motor cortex primary because this is what's going to detect and direct motion right in this particular area so these are some of the things that that we're going to be talking about in this video and so other things that will be coming up as I mentioned this sort of cognitive thinking and decision-making occurs over here this location of the brain if you're wondering how how do we know some of the things that we know that's that's a complicated question it's a fair question part of it is through decades of research in neuroscience part of it is amazing technology and imaging like for example this functional MRI right here which is showing us more and more where different processes are occurring in the in that cortex of the brain and cerebrum and so let's talk a little Anatomy and so that we can get some common footing here so if you took the brain and you slice it right here and you were looking at it front on in other words a frontal plane you'll notice that there's gray matter toward the outside so toward the outside of a structure or an organiser - as the cortex so this is the cerebral cortex and it's grey matter those of you may know is because the fact that it has many nuclei or soma of neurons and so therefore it has a darker appearance whereas the white matter has more axons in other words tracts of extensions from the neuron which are myelinated and therefore giving a white appearance because of their lipid density okay so you have gray matter and you have white matter in in that cerebrum and also I promised that I would mention this here that you'll notice the brain has all of these convolutions and so you'll notice here that each little fold is known as a gyroscope lauryl gyrus for singular or sulci for plural or sulcus you see this in indentation right here it's referred to as a sulcus right in here and this increases surface area of the of the of the cerebrum and therefore increases the number of cortical neurons and therefore increases the brain's ability so pretty awesome you'll notice here in this orange line that there's a larger deeper groove called the fissure and since this is separating the left and the right hemisphere of the cerebrum it's referred to as the longitudinal fissure right there it separates the hemispheres of the brain now the two hemispheres have different functions although they are structurally similar and that would be part of our discussion today looking at some of the functionality of what's happening but they're structurally similar so I wanted to point out something kind of intriguing at the top of the video which is I find kind of curious like for example you know you have a right eye and a left eye so an image coming in being picked up from the right side and over the right visual field is then being picked up by the the retina of the eye and then brought back by the optic nerve and then there's sort of a little cross over right here there's a optic ky's chiasm that occurs and this allows for images from the right side of the brain to be picked up over here on the left hemisphere and in particular on the back part of which is where the primary visual cortex is being picked up back here and then again images from the left side optic chiasm is being picked up over here over on the right the right side and so there's a there's kind of a cross that occurs inside the cerebrum I find that to be good pretty cool so similar situation is occurring in the somatic sensory information coming into the body from one side it's being processed on the other side in the brain like for example if we're picking up something in terms of temperature we're feeling something in a sensory neuron that afferent neuron unipolar neuron is going to be then bringing that information up here here's the dorsal root ganglia inside and the spinal cord and then it's going to cross over and it's going to be perceived and detected over here I mentioned before in the primary somatosensory portion of the cortex okay so same thing over on on the other side it's crossed over to the outside of the hemisphere and so let's talk a little bit about lobes I mentioned hemispheres but there's also lobes of the cerebrum and those are named after the skulls for which are protecting them or that are directly above them so we have the frontal bone which is on top of the frontal lobe then we have parietal lobe there's two parietal lobes on both sides of the brain and then we have a temporal lobe right here right below the temporal bone and then we have the occipital lobe which is right behind the occipital bone and so we have these various lobes of the cerebrum I wanted to point out this particular area right here this central sulcus right in here that's highlighted in blue the central sulcus is able to divide the interior toward the front the frontal lobe from the posterior parietal lobe as you can see right there okay you might notice there's a couple of other cool things that that I'm not there that are not highlighted here but this is the PIA mater covering the left side of the hemisphere the pia mater is the innermost mint man in G which are layers that surround the brain and then the arachnoid mater in this case it's villi because it's sort of convoluted but that particularly er as you can see over here is just above that and then the dura mater has been removed in other words they had the hard shell of the of the of the brain the central sulcus as you can see right here as well okay so this is a lateral view of the brain of the central sulcus now this lateral sulcus which is shown right down here is going to separate the frontal lobe which is right there frontal lobe from the temporal lobe which is located right over here okay and then we have this one the parieto-occipital sulcus which is located back here as one might imagine that separates the parietal lobe from the occipital lobe which is located most posterior right in this area it's a little Anatomy right there so here's your parietal lobe here's your occipital lobe here's your frontal lobe and here's your temporal lobe located right here now the truth be told if these were not labeled it's sometimes difficult to you know delineate where exactly something starts and stops but further you know more that you're studying this the more you'll be able to identify those particular landmarks that separate the lobes like for example the central sulcus we were just talking about and lateral sulcus that is what you use as a guiding measure like okay there's the lateral sulcus there there's the temporal lobe and there over there is on the frontal lobe that's that sort of thing so it's possible now I find this to be pretty cool so if you were to take that lateral sulcus and you get some retractors and you literally pull it back a little bit you'll see that there's sort of like a little island or Islah of lobe a cortex that's actually in inward that you cannot see unless you retract back along that that particular sulcus and it's it's more medial to the lateral sulcus meaning more towards the center of the brain I mean that to be kind of interesting here you can see it in color in a cadaver so you take some retractors and pull it back and it's highlighted right in here so it's a it's a deep folded part of the cerebral cortex and the that's separating the the temporal lobe and the parietal lobe and the frontal lobe right in this area but if you pull it back you can see that sort of little island of cortex below and it's thought to be and in it when I say believed to be because we're always learning more and more about the functionality of the brain let me assure you not everything is known and there's more to come and so perhaps you'll be involved in discovering something about the functionality of the brand in your future studies and that we call so it's believed to be involved in consciousness and plays a role in all kinds of diverse functions ranging because it's a little bit more internal so it has an association with the limbic system so there's an emotional component to this particular area and it also helps to regulate various Homa hemostat homo static mechanisms or in other words keeping things regulate regulated and inside the body so let's look down the superior view of the brain and again here's the longitudinal fissure right here and then we're looking at the different hemispheres now I wanted to point out here you'll notice this pre central gyrus in other words it's just to the front right in here precentral gyrus and then just just behind that area right there is the post central gyrus right in here and I bring these to your attention because those are particularly important areas that we're going to be discussing shortly I mentioned them at the top of the video this post central gyrus is going to be in the primary sensory area and this pre central gyrus is an area where directions are given for conscious movement or of motor function in other words movement and muscle so those are really important areas of the cerebral cortex and so I'll come back to the cerebral cortex in a moment but I should point out that you know there's all of this white matter below and so when we get into this conversation we want to make sure that I'm giving equal due to not only the cerebral cortex which is the gray matter but what's known as the subcortical cerebrum in other words the white matter because it does matter so it's white because it contains myelinated axons that are projecting from the cerebral cortex so that so the soma is projecting its axons down all the way through to not only to cross between the hemispheres as we'll talk about but also all the way down into the brainstem and down the spinal cord for that matter so this is a frontal plane of the brain indicating this white matter so let's talk about this white matter that's that's part of the subcortical cerebrum and so I wanted to mention there's fibers that move that connect one hemisphere for to the other I mentioned that those are known as Association fibers and II and you can see them here so these Association fibers come in two kinds so they're they're referred to as the come miss miss sorrel to miss oral in other words bridge commissural fibers that these are bands of fibers connecting the two hemispheres commissural fibers and those are not shown in that particular picture but we have these arcuate fibers which are short as you can see up here these arcuate fibers which are connecting different Jireh to one another and then we have these longitudinal fasciculus vesicular which are longer bundles which are shown right here that are connecting frontal lobes with other lobes of the body and within the same hemisphere of the cerebrum okay and then we have projection fibers now these projection fibers are the ones that are if you will connecting the hemispheres right in here I'm sorry misspoke the commission can commissioner all fibers are the ones that are connecting the hemispheres as you can see in red but the projection fibers are the ones that are actually traveling all the way down into the midbrain and down into the brainstem and then all the way down into the into the spinal cord and back and forth so you have these projection fibers that are sort of ascending and descending right in here and then we have the commercial fibers so these commercial fibers that are going laterally so I decide one of the more pronounced commercial fibers is a structure known as the corpus callosum and it's a band of white matter and that again that's obvious or maybe not obvious but it's white matter because it contains axons as you can see here the corpus callosum and so it's interconnecting the hemisphere and it allows information to travel from one cerebral hemisphere to the other corpus callosum here's the coronal section of the brain you can see that corpus callosum here and this is all the white matter this is the gray matter of the cerebral cortex so this is one of the more pronounced of commercial of fibers but there is another one as well that I wanted to point out there's this interior one right here do you see this right here this bridge so here's the corpus callosum right there which is really significant and then this is the anterior commissure right in here now you may notice look at these lateral ventricles right here that are that are separated these are chambers of the brain this is separated by a septum sort of like your nasal septum but it's not a nasal septum it's the septum pellucidum right over here alright but so these are these are white matter commissure v komissarov fibers that are connecting the hemispheres to one another the corpus callosum being the more significant now these projection fibers is over saying before the ones that are traveling up and down not only from the the cerebrum but all the way down into the spinal cord and so they link the cortex the outer part of the cerebrum with the diencephalon and all the way down to the brainstem all the way down to the spinal cord but they also go down into the cerebellum as well so that's pretty cool and so an example of some of these projection fibers is a particular area this white area which is known as the internal capsule okay so it's a band of white matter in the middle of some gray islands if you will so this is where all the ascending and descending projection fibers or axons are traveling so it's a significant area so internal capsule so check it out it's right over here the internal capsule do you see that right there and right there so these are the projection fibers that are traveling all the way down and then ultimately down in the rest of the body internal capsule now more detail about that so here's the internal capsule as you can see look at all the branches of tracts if you will of axons that are traveling down and then all the way down mentioned before into the brainstem the midbrain the pons the medulla and then all the way down the spinal cord it's kind of in the shape of a V if you will and then the fibers sort of tease themselves out and go to different areas of the cerebral cortex it's kind of B shape this internal capsule alright now I also wanted to point out do you notice here the gray matter doesn't just exist on the most peripheral part of the cerebral cortex there's also some bodies if you will of gray matter that are sort of inside the brain and sort of in between areas of white matter like for example that I was just mentioning the internal capsule let me go back to this picture do you see the internal capsule right there there's these little islands of gray matter you see that right there and so let's talk about that so there's these masses of gray matter and again the gray matter is gray because it stains a little darker and it's darker in appearance because there's a lot of Soma in that so they're embedded within the white matter of the cerebrum okay and it plays an important role in motor function helping the motor nerve neuron area of the cortex it's one of its function and it's referred to as basal nuclei so basal ganglia so so many terms but don't get overwhelmed don't be intimidated so basal meaning something like below or low and nuclei because that's what we're talking about these are the some of the nuclei so ganglia because they're pronounced structures in other words their their masses of of soma which give them the form which is what the term ganglia is coming from so the basal ganglia are gray matter within the the internal structure of the cerebrum and so they also help to direct subconscious activities as well and so you can get really into this as you know one can imagine this is brain science it's not it's not for the for the for the for the weak or faint of heart so they some of the some of the functions is thought to play a role in cognition it's thought to play a role in emotional function as well again associated with the limbic system as well and you'll notice some of the names right here are kind of this one in particular length of form nucleus right in here okay so these are the particular nuclei which are the gray matter which are below which are like little islands if you will in the middle of all this white matter okay and then here's those important projection fibers that are occur in the internal capsule that I was mentioning before right there okay so a little bit more so their various names for these basal nuclei and again with a variety of functions but I just wanted to point out fact that there is gray matter below not just on the cortex I find this picture to be particularly interesting too because you can really see it three dimensionally in terms of what these structures are really all about okay and so you can see the gray matter located here although it's colored but you can see all sorts of other structures here's the pineal gland the fornix which is the structure or this arching area right in here you can see that they're showing a little bit of the ventricles here it's the third ventricle you can see over here the lateral ventricle we were talking a little bit before just to give you some orientation about the septum pellucidum which is right here okay so again just to sort of close the book on the on the on the function of these basal cell or basal nuclei ganglia they're involved in subconscious control of muscle skeletal muscle tone as well and it also it's believed that they're they're involved in the coordination of learned movement patterns like blocking incredible okay and then finally this lateral perspective right here from the side you can see how these the gray matter is in has these really cool sort of scale like sort of like hooking arching kind of particular structures that are found in the internal part of the the cerebrum now in this area I have to mention this there's you know there's some other basal nuclei there's another group of sub for Tikal in other words below the cortex cerebral nuclei that are very significant and collectively they're they're referred to as in these two lobes right here the thalamus and so that you might be familiar with the thalamus it's sometimes called the diencephalon which is named after the embryonic structure that it develops from so the dominance what's that doing well that plays an important role in relay and routing sensory information because most of the sense neurons are passing through this thalamus and they're being processed there so that's one thing and then not only are they being processed there but then nerve tracts then carry it up to the cerebral cortex which does even more processing you can see here in green that the two left and right thalamus okay so getting back to the cerebral cortex okay so I wanted to make this really clear because I think it's rather important so in the cerebral cortex the outer part of the brain the gray matter it can be divided into two particular areas there's one area known as the primary complexes that are sort of the motor area that directs movement so the direction of movement but then there's a primary sensory location that is detecting the various senses of our temperature and feeling and pain and those sort of it thanks any detecting sound but then there's other areas in the cortex that are referred to as Association locations or Association complexes and those are the areas in the cerebral cortex that we were about to talk about that are involved in understanding and perceiving what it is so in other words you can hear my voice and that that's being picked up by the by a primary sense sensory location but then understanding what I'm saying and recognizing my voice and who what I'm talking about and understanding it occurs in another location entirely and so this has to be discussed and so these I was mentioning before this this again here's the frontal lobe right in here so the central sulcus which is where this pointer is gone the central sulcus right there is separating this primary motor which is toward toward the front right there of that and then the primary sensory area which is just a little to the back of the central soakin sulcus and so this is again detecting sensory information detecting it but the motor is ascending and directing muscle movement but in terms of sensory there's different Association areas where your your going to be able to recognize and understand what those are senses are all about and so again here's a nice picture showing the central sulcus and so what we talk about is the pre which is towards the front and the post central gyrus so this is an area right in here which is primary somatosensory and this is primary motor which is in the red okay so this motor area is again trying to really emphasize this is the precentral gyrus of the frontal lobe here it's highlighted in blue so you can clearly see it again if the blue wasn't here it might be tricky just saying but again takes time it directs a voluntary movement so this area is directing your muscles to move it's the primary motor cortex yeah there it is okay so there it is right there in red okay now this post central gyrus is with the sensory area so this is receiving sensory information so the the afferent messages are coming in to the brain about oh I'm touching something I'm feeling pressure ouch it's hurting a temperature all of these things are being picked up in this particular area right over here highlighted in blue which is the post central gyrus okay and there's lots of images that you can find that are kind of cool about this so this is where the particular areas you believe this that the location in the body where if some of these touching your hands and your fingers this is where in the brain you'll actually be detecting that okay I find that to be kind of interesting so again just to emphasize this so the primary area is the basic directing it's detecting I'm sorry it's detecting the sensory stimulation in the Association area is one of the areas that are it's characterized because it's far developed in the cerebral cortex in the brain in general and so it's necessary for us to to remember to recognize and to perceive the various senses okay and so these are what we referred to as sensory Association areas that that monitor and interpret the arriving information coming from the sensory area of the cortex so this interprets the inputs so if it's trying to understand what is happening when sensory information comes in so in other words visual so okay you might be able to again you know when the vision comes in it's it's in the ops if it'll lobe in the back that you're actually interpreting yes I understand I recognize that person or auditory Association in other words monitoring the fact that I do understand what is what it might what I'm hearing okay so and then I wanted to also point out in terms of Association that just in front of where the movements are being directed like right over here over this promoter area right in here is the association area which is where it sort of coordinates learned movement I find that to be kind of interesting as well hopefully you're not becoming too overwhelmed by by all this like just state stay with me on this and so basically this this somatic sensory Association area is what people love to talk about when they want to talk about this the the cerebral cortex they want to say look this is where we where we taste look this is where we see things and again we have some confidence with that I want to point out through years of study and functional MRI but I wanted to note that really the there it's complicated and so it's not precise I cannot say with with all confidence this is exactly where hearing is occurring this is exactly where touch is coming but but I can give you of this basic introduction to those concepts in other words you know I mentioned this before the primary motor cortex is the voluntary control of skeletal muscles that's important the primary sensory cortex is the perception of these various things that that's where we're confident about that but as far as you know the visual the auditory these kinds of smell and hearing an olfactory they occurred specifically in certain locations but there's a little crossover just just saying so take it kind of lightly from this point on when it comes to the Association centers of sensory information so we have smell and taste generally in these areas right over here okay so smell the old factory and taste is occurring right in this particular area right in here so for example if you're smelling and tasting a nice cup of coffee right in there and and then hearing like for example when we hear something hear something but then we interpret what it is it's a bell maybe it's the ringing breath it's a sound for breakfast is coming so that's being picked up in the in the temporal lobe okay so that Association centers in the temporal lobe which makes sense because it's a it's pretty close to the ear okay and then we could actually maybe we come downstairs and we say hey there's a nice cup of coffee waiting for me and the visualization of the cup of coffee is happening over here in the occipital lobe okay so the the understanding that that is a cup of coffee right there so the information and then we get you know and then from the prior loh we have some things in the cerebral cortex in terms of spatial manipulation in other words like when we're trying to get a sense of you know space in terms of grabbing the cup and orientating our spatial location and then also things like for example the heat of the cup are being picked up in the parietal lobe as well our perception of that and so these all of this information is then in in some instances are integrated and so we have these particular integration centers that receive information from a lot of different both sides of the cerebral hemispheres and what they do is they try to analyze this and so let me give you two examples of what I'm talking about in terms of integration areas this one area known as this Broca area okay and it was a Pierre Broca I was was working with some patients that were injured and they had they were had damage to their brain in this particular area highlighted in red and they lost their ability to speak after an injury to this particular of the sort of posterior area of the frontal gyrus right in this right in area and it became known as the Broca area and so this is now an area which we believe is important to coordinate vocalization function in other words to generate a speech in this particular area so that's kind of interesting right there I just wanted to point that out now there's another area this sort of Warnecke area it's located in the temporal lobe on the left side of the brain and it's involved in comprehension of speech okay now when I said that the broken area was sort of the production of speech the the Warnecke area is basically trying to understand and when somebody is saying something to you it's being had understood in that particular area so it's pressing curiously only in one hemisphere and it receives information from all of the sensory association areas and so it's kind of an if you will I'm mentioning speech but it's sort of a general area as well so it's coordinating all kinds of things so not only like what you're seeing and comprehension basically what you're if you're reading if somebody's reading to you you're looking at the words it's kind of where you're Frank trying to figure it all out I also need to point out that in addition to those two areas this blue area is this prefrontal cortex part the the most interior part of the frontal lobe is where the most abstract intellectual functions are occurring in other words predicting the future events or the consequences consequences of various actions decision-making is occurring over here in the prefrontal cortex so that's an area of total interest and so I also wanted to mention that the hemispheres they're sort of this lateralization occurs there's functional differences between the left and right hemispheres so each cerebral hemisphere is performing certain functions that are that are not ordinarily performed by the opposite hemisphere and so this is also something that's kind of common you'll hear people discussing this you know with a left left brain or right brain conversation and so in most people the left brain so the left hemisphere is controlling things like reading and writing and math and in decision-making again that's occurring more in the front and speech and language as I was referring to before these are on the left side of the brain the right side of the brain has more to do with again related to senses of touch and smell sight again toward the back right in here in recognition of faces and voice inflections the right side of the brain okay and then finally I want to talk to you a little bit about how brain activity is monitored this is kind of a clinical finish to this conversation about the cerebrum so we have the ability to attach electrodes onto onto patient's right right on top of the skull and so what this is is that we're looking for that by doing this we're looking at electro encephalogram or EC or EEG electroencephalogram so electrodes I said before replaced on the skull and that it can actually detect electoral electrical activity that is occurring in the neurons within the brain and these are detected as little waves and I'll show you an example of a printout of this in a moment and so we've categorized these particular brain waves and four basic types there's alpha beta theta and Delta so let's look at these so this is what I was telling you about like a printout right in here and these are known as the Alpha waves and so this is sort of if you will normal so found in healthy awake adult at rest with the eyes closed right there so there you go and so the beta waves are more high-frequency and found in adults that are concentrating or mentally stressed I could say like for example those watching this video we might be exhibiting beta waves so theta waves are found in children right in here and so check that and check this out these are a little bit of higher amplitude right in here and there they're also found in intensely frustrated adults and I find that to be kind of funny too because maybe that the adult is frustrated because they're actually hanging out with the kids and so they're both exhibiting Delta waves but it could on a serious net it could indicate brain disorders in adult these theta waves and so that's indication again a physician may want to take a look at these following trauma to the to the to the skull for example and then finally the the fourth type of wave is a delta wave you might be familiar with this these are part of everyday conversation so these delta waves are the sleep pattern that you have there that you'll normally see so it's found while you're sleeping but it's also found in adults that are awake with brain damage and so this would be very detrimental if you're exhibiting Delta waves while you're awake and then finally I wanted to mention this that a seizure okay is okay so these are normal waves the brain waves right in here a seizure would be a change in that the East e SC of of a patient and so this rapid high amplitude right in here high frequency is the result of the seizure and a seizure might go unnoticed but then again it could also turn a person unconscious and it can also result in involuntary muscle spasms or what would are known as convulsions and so that both of those are not good okay so just to sort of wrap this up hopefully you enjoyed this conversation about the cerebrum and I I know it's very valuable and it was sort of a basic conversation there's a lot more to be to be studied like all things and so hopefully this is the beginning of a great journey that you'll have studying the cerebrum and I hope you enjoyed this particular video and thanks for watching

Channel: Ray Cinti

Views: 39,794

Rating: 4.862319 out of 5

Keywords: Cerebrum

Id: 1-5Dc8w6Cp4

Length: 41min 56sec (2516 seconds)

Published: Thu Apr 13 2017