hey class on to part 2 of the brain and we're looking at the cerebrum now the cerebrum is you could argue the most advanced portion of the brain which means that our 15 minutes of discussing it today is just really not doing it justice there's plenty more that can be learned we're just going to hit some of the most basic structures and functions and revisiting this image from before this darkened region all of this is the cerebrum the largest region of the brain and it's made of two cerebral hemispheres so when Anna left a left hemisphere in a right hemisphere and they're divided by the longitudinal fissure remember earlier we talked about the dura mater and how it makes folds like the falx cerebri that goes down the midline of the brain so when we say the cerebral hemispheres are divided by the longitudinal fissure inside that Fisher is the falx cerebri these two hemispheres anatomically they look the same there are some functional differences that will mention briefly later on but one thing that you may have heard before is that the hemispheres operate contralaterally which means the information is crossing over so like you receive sensory information from and some motor commands to the opposite side of the body and we don't really know why that is and if it there's any significance to that much of what we'll talk about is looking at the cerebral lobes so many of these lobes of the brain match the names of the cranial bones so you have a frontal lobe parietal lobes occipital lobe and temporal lobes and then there's also this insula or you'll hear it it as it called as the insular lobe which is like the fifth type of lobe of the brain and previously and our intro to the nervous system we talked about gray matter and white matter gray matter in the brain includes the cerebral cortex outer portion of the cerebrum in their basal nuclei remember this term nuclei in this case we're saying is a bundle of gray matter which is just cell bodies a bundle of cell bodies embedded elsewhere in the brain so not in the cerebral cortex but a little island of gray matter I call them basal nuclei and if you look at the brain really the most noticeable thing right away is the gyri in the sole sigh so those are these grooves and fissures on the brain but then there are even bigger fissures that we call fissures altogether these serve really the same purpose you're trying to increase the cortical surface area because you want to fit more synapses between neurons in there and as it says it's like a crumpled piece of paper so if you have a piece of paper you crumple up small you've made all of these folds and ridges in the paper and you can fit it into a much smaller space here's some of the Anatomy just looking at the Fisher you've got some of the meninges still showing you have cerebellum and portions of the brainstem that we'll talk about later but you can also see the lobes we start to see the lobes being named on these diagrams and as we look at the lobes this table just captures some of the most basic overarching functions of each lobe and for some lobes we'll talk about them in more detail and others we won't really get into much more detailed in this but for starters what you should learn is that the frontal lobe contains a specific region called the primary motor cortex and as the name implies this is the primary place in your brain that when you decide to move muscle which means we're talking to skeletal muscle when you decide to move it this is where the command originates the frontal lobe specific part called the primary motor cortex the parietal lobes have a primary sensory cortex really close to the motor cortex right next door there's primary sensory cortex and processes a lot of sensory information but with a few exceptions like vision and hearing and smell so when we're talking about touch and specific things that are similar to touch like pressure and vibration painting temperature or I'll processed here and also taste so if you're trying to remember what lobe processes certain sensory receptor signals chances are it's the parietal lobe but occipital lobe as a visual cortex where we process visual stimuli so it's a pretty big lobe big portion what it does is just processing visual information the temporal lobe which is you know right about here it will not surprise you to know that it processes auditory information and if you kind of send your pinkies out a little bit more towards the front you can reach your nose to remind yourself that it also processes olfactory stimuli for the sense of smell all of these have what are known as association areas where they're integrating and processing data they're also kind of helping plan out motor activities but we'll talk about those in a moment we'll have some examples of those but it is in short it's kind of like checking in with other parts of the brain to make new associations you know I figure out what the brain should do with this information is gained and don't forget about the insula or you can call it the insular lobe it's kind of deep underneath this big sulcus called a lateral sulcus on the side of the brain we'll see more on that in a minute so here is a color-coded map that's showing some of these lobes and structures for example when we talked about the frontal lobe all of this is frontal lobe but specifically we mentioned the primary motor cortex that's here that's where you were conscious control of skeletal muscle originates and this Ridge this is one long continuous Ridge it has a name the precentral gyrus precentral refers to the fact that there's a structure here called the central sulcus not a huge fissure which is one of these many sul sy but it happens to run right down the center of the brain so it's called the central sulcus so pre in front of before the central sulcus is the precentral gyrus a ridge in front of the central sulcus so that's the structure and what it does what its function is is it's the primary motor cortex then behind or after the central sulcus is another gyrus the post central gyrus after the central sulcus is a gyrus this is the primary sensory cortex that's the one that processes touch pain temperature vibration pressure and so on you'll also see these association areas labeled an association area here there's one here there's one here in here so we'll talk about those again in a second and then you can see the other lobes here like this is really a great picture to see how the insular lobe is tucked away and have hidden inside of the brain and we can see one thing it has is the gustatory cortex to help process the sense of taste now if we read below we'll see a note that each of the regions of the cortex have a nearby Association area and so we said that what do these do well they're not receiving sensory information directly or directly generating motor commands they are making associations they're trying to interpret things interpret sensory input coming from elsewhere in the cerebral cortex because of the parts of the brain are in constant communication so they're going to use that information to kind of create an understanding of your world we can look at an example of that in a moment but let's talk frontal-lobe we already mentioned the primary motor cortex where it's found and what it does in this case an association area would be like using memories stored somewhere else but making an association between these memories and these movements so helping with learned movement patterns I'll coordinate your behavior so note that when we have an association area we're accessing different information from a different part of the brain the prefrontal cortex that's a region at the very front of the frontal lobe prefrontal cortex here's where you've got intellect reasoning judgment concern for others empathy personality traits management of your emotions the ability to interpret events predict if you predict the future not literally but to you know use what you know about the world to try to understand what will happen in the future and so this region is actually can be a source of anxiety since you are able to understand the world and predict the future and this region of the brain is what was targeted during lobotomies and so if you don't know anything about the pretty sordid history of lobotomies in the United States definitely worth a look pretty sad awful time with even people like you know JFK is not someone from my lifetime but you know it doesn't seem like ancient history by any stretch and his sister was one of the last American citizens to be lobotomised and depending on which books you read it was for something as simple as being a very outspoken female at a time where men and power didn't appreciate that so it's it's tough reading but it's worth a look the prefrontal cortex develops later in life and is impacted by your social environment so you know when you tell teenagers to make good choices they may not be able to they haven't fully developed their prefrontal cortex and finally this area is linked to the emotions which will mention later is called the limbic system saying the frontal lobe is good for besides initiating these voluntary skeletal muscle controls and handling all of this fancy stuff is that there are some a language area called Broca's area where you produce speech another area you will hear about our encounter at some point is their Nikki's area in the temporal lobe where you comprehend speech so you really need both of these intact to have these meaningful communication through verbal communication so try it alone but most of these lobes will be much shorter kreidel lobe has your primary sensory cortex we already talked about where that's found and what it does and like all these lobes there's an association area like if you process the sense of touch that's okay but you really need to access other parts of your brain to comprehend based on that touch what size is this what does its form or its texture or its weight or whatever all of these things you're accessing different reference points in your brain to make these associations the temporal lobe we mentioned both its ability to process auditory and olfactory information so one thing an association area might do is take those sounds that are processed and turn them into context so participating with Broca's and Wernicke's area are other parts of the temporal lobe that are trying to help us understand what we hear that will factory lobe is pretty deep the olfactory cortex rather is pretty deep in the temporal lobe taking input in from the olfactory nerves and it's tightly connected to that limbic system we mentioned before that is responsible for emotions and also memories so some people have very evocative connections between certain smells in certain feelings or memories I've never quite felt that way but it's a thing Loeb has the visual cortex to process information from the retina and it's an association area would interpret that data again just put it into context you know so like if you see a certain pattern on a shirt that's okay but if you realize it's you know the album cover from some you know emo band from back in your college days if you're like you know about that man that's crazy and then you get all your memories of you know the tattooing and the partying and the rocking yeah that's making those associations a few more things about the cerebrum there is some specialization across the hemispheres as we mentioned so if you hear about people saying left-brained or right-brained there appears to be some truth to that with the left hemisphere being better at things like speech language and math and the right hemisphere processing things like touch and spatial visualization and of course there's lots more that can be said about that but we're just going to very quickly peak of this concept of hemispheric specialization one of the other things we want to acknowledge is that there's not just all this gray matter in the brain in the cerebrum of the brain there's also white matter which means there are axons typically myelinated axons this is where the information is zooming back and forth between these cell bodies and these synapses and there are different names for this white matter in the brain so for example you have Association fibers which are intra hemispheric so they're inside of one hemisphere they interconnect different cortical areas within a hemisphere call them Association fibers if you want to go to the other hemisphere to be inter hemispheric we call those commissural fibers the classic example is the corpus collosum corpus collosum is this kind of curled Ridge or line here that's the main linkage between the right and left cerebral hemispheres remember the hemispheres can't talk all right here is that big chunk of dura mater called the falx cerebri so if the hemispheres want to talk they have to talk through this in this image the scalpel has sliced through the corpus callosum otherwise it would still be attached to the other side of the brain and last there are projection fibers the named projection would kind of suggest these are projecting out further away than these other examples so we're talking about going down to other regions of the brain like the midbrain or the pons cerebellum or down to the spinal cord if you notice these are kind of an alphabetical order you know that a is what you might want to think of first because that's intra hemispheric those are short distances and then you go to the C and by the way corpus callosum also starts with C's so these C's are going a little bit further between the hemispheres and when you get to P now you're projecting out very far away from one part of the brain to another or out of the brain altogether and don't forget those basal nuclei gray matter islands embedded in the central white matter so their functions are subconscious control of skeletal muscle tone that's meaning basically that your skeletal muscle is kind of always primed to be ready to fire and the basal nuclei assist with that they also help with coordinate coordinating these learned movement patterns and processing integrating a bunch of stuff from the cerebral cortex one of the examples of this that kind of takes into account some of that is like if you drop a pencil on the floor and you bend down to pick it up like you've done it a million times but that's a pretty tricky process to coordinate you know the balance of weight as it shifts between your legs and as your center of gravity kind of tilts forward as your hand reaches out you have to be aware of its movement through space like that's a lot of data coming in and going out and the basal nuclei help coordinate that and smooth it out so that's the cerebrum that's kind of the biggest busiest part of the brain we quickly move through the rest of the brain here in the following video lectures but for now I'll say goodbye