Hi. It's Mr. Andersen and in this video I'm
going to talk about the brain structure and function. Remember structure is what it's
made up of. And function is what does it do. We sometimes refer to this as the anatomy
or structure and physiology or the function. And so the cool thing is that we're going
to go through seventeen different structures in the brain, kind of lay out the basic plan
of the brain. But you are using your brain to process it. And if you do a good job when
we get to the end and I review all the parts, you should be able to tell me what their structure
is and what their function is. And so what type of organisms have brains? It's the animals.
Animals use nerves. They have muscles to move around. And so they have to organize that
movement. And so they use a brain. And so if we look at the two basic body plans of
animals, some are radially symmetrical. In other words they're built around almost a
tire. And then some are bilaterally symmetrical. In other words a tiger you could draw a line
right down the middle. There's going to be a clear right side and a left side. There's
going to be a clear front and end. And as we became bilaterally symmetrical we had to
organize that movement. And so this is a simple animal body plan. And so this animal is going
to move towards the right. And as it does so it has to take in information. We call
that sensory information using neurons. And so right now you're taking in sensory information
from your eyes, from your ears. And then inside your brain you're going to integrate that
information. You're going to make sense of it. And then you're going to figure out what
you want to do. How you're going to act dependent upon that. And so then we have this loop of
motor neurons out. Or motor nerves. And so this loop in simple animals is also important
in understanding how our brain works. But if we look at these real primitive brains
we find that they have a real common structure. They have these four humps. And we call those,
well the first one is not a hump, but the spinal cord. We then have the hindbrain, the
midbrain and then we finally have the forebrain. And we find this consistent throughout all
animals. And if we look at something like a shark, it pretty much looks just like that
primitive brain. You can see down here we've got the spinal cord that's bringing information
in. We then have the hindbrain, the midbrain and the forebrain. And so one thing you should
remember is that the closer we are to that spinal cord, the more basic the functions
are. And so we're right down in this hindbrain. It's going to be basically keeping the heart
beating. Keep the circulation going. Digestion in the shark. But when a shark decides to
attack you or it has some kind of an emotional response, that's going to be way up here in
the forebrain. Now if we look at you when you were really little, when you were an embryo,
you had a brain that looked very similar. You had a spinal cord. You then had a hindbrain.
You had a midbrain. And then you had a forebrain. But during development that brain changes
radically. And so this is what an adult brain looks like. So we still see that spinal cord.
We then have the hindbrain. We have the midbrain. But look how large that forebrain is going
to be. So that's where all of those emotions and memories and all of that thinking, we
generally attribute to the brain is going to be in the forebrain. And so let's get to
the actual anatomy. And so there are going to be 17 parts that we're going to go through.
So you should always be thinking what's the name of the structure? Where is it? And then
what's the function, what does it do? So if we look at a basic brain plan we find these
four things jump out right away. We're going to see the brainstem. We then see a cerebellum
on the back of the brain So again to get yourself oriented right the eyes are going to be right
up here. So this would be towards the back of the head. So that's going to be the cerebellum.
We then have the area of the thalamus hypothalamus. And then finally we have the cerebrum which
is going to be that dominant upper portion of the brain. And so let's begin with the
brainstem. The brainstem is broken down into three individual structures. So if we start
at the bottom we've got the medulla oblangata, the pons and then we finally have the midbrain.
And so those three things, medulla oblangata, pons and midbrain make up what we call the
brainstem. So that the structure. What's the function? Well it really does two things.
The first thing it's going to do are these more basic needs. It's going to keep yourself
breathing, keep circulation going, digestion, swallowing. All of that is going to be controlled
by the brainstem. If there's any damage to the brainstem it's going to be catastrophic.
What else does it do? Then we have information coming in. So we have sensory information,
just like that worm did, coming up to the brain. And then we have motor nerves going
out. And so the brainstem is important in routing that information and filtering that
information, sending it where it needs to go. What's behind that? We have the cerebellum
The cerebellum, and the function of that is motor control. So as you do sports, for example,
it's the cerebellum that's giving you that coordination. And it also gives you motor
memory. So as you learn to ride a bicycle and you remember how to ride a bicycle that's
going to be thanks to your cerebellum. If we keep moving up we now have the thalamus.
The thalamus again sits right on top of the brainstem. And so the best analogy I could
come up with is a router. It's basically sorting data and sending it where it needs to go.
If we were to look below that there's a little structure here that's incredibly important.
It's called the hypothalamus. That's going to be really right above the roof of your
mouth. What is that accountable for? It's homeostasis. So it's maintaining body temperature.
It's maintaining osmolarity. All of that stuff is contained right up in the hypothalamus.
Also important in circadian rhythms. And then if we look right below that you can see a
little gland hanging out. And one-half of that pituitary gland, the posterior pituitary,
is technically part of the brain. And it's important in basically sending off hormones.
And so there are nerves that flow into that pituitary and it's sending out things like
antidiuretic hormone. That keeps your water balance the same. Oxytocin would be another
important hormone that comes out of there. If we keep moving up then we get to the level
of the cerebrum. What's the function of the cerebrum? That is integration. So what we're
doing is making sense of all of that data that comes in. Now what makes up that cerebrum
are going to be all these neurons. There's tons of neurons that are connected together.
Billions of neurons. And billions and billions of synapses or connections between these neurons.
And that's where we're making sense of information as it comes in. Now if you were to look at
this image right here, so of that brick wall, so take a moment to look at that and I'm going
to show you some other images. Now focus on this. And then that. And then that. And what
we find is as you look at those images your brain is integrating. It's making sense of
all that information. And it used to be a black box. We didn't know really what was
going on. But now we can use technology like a functional MRI. A functional magnetic resonance
imaging. And what we're looking at here is a brain in action. So this same study was
done on females. And what they would show them is something neutral, like a brick wall.
And then a kitten. And then something like dirt. And then something like puppies. And
so what we're seeing is as those images are switching back and forth we can start to see
where blood is flowing around in the brain and we can start to figure out what the different
parts of the brain actually do. We're able to figure out their function. So when we're
looking at the cerebrum every picture that I've shown you is from the side. So the eye
is up here. But if we were to rotate that 90 degrees now were looking at it head on,
we'll find that there are two hemispheres. There's going to be a right and a left hemisphere.
Now they are connected in the middle using something called the corpus collosum. So that's
a connection of nerves in between the two hemispheres. And we do tend to show lateralization.
There are going to be certain things that we put kind of on the left side of our brain,
like mathematical reasoning and logic. And things that we put on the right side like
facial recognition. Now this is plastic. In other words we can move these functions back
and forth. And you can even have a radical hemispherectomy, where you're cutting one
of these out and you still have a functioning brain. Now if we were to go right below the
corpus collosum we get into this area called the basal ganglia. And it's made up of a bunch
of nuclei. What are nuclei? Or what is a nucleus in a brain? It's basically a bunch of neurons
that are right next to each other that have the same function. And so all of these nuclei
together make up what's called the basal ganglia. And you can see this would be the corpus collosum,
connecting it together as well. So this is below the cerebral cortex. What's the function
of that? Well scientists have been able to figure out there is this complex interaction
of inhibition and excitatory response between these neurons. And basically it controls a
lot of our motor control. And if you have somebody who has Parkinson's disease then
we're having problems in this basal ganglia area. As we move farther up the brain we eventually
get to the cerebral cortex. And that's going to make up about 80 percent of the brain.
So it's most of the brain itself. And it's broken apart into these four lobes. And so
if we start in the front of the brain we have what's called the frontal lobe. What's the
function of that? It's mostly executive function. So it's kind of like the boss of your brain.
It's emotional control up there. And if we have people who have damage to that frontal
lobe they have really huge emotional swings. As we move back towards the back of the brain
we get to the parietal lobe. What's the function of that? It basically is sensation. It's you
dealing with and reacting to your environment. So we have a lot of neurons coming in here
from a sensory input. As we move to the back we have the occipital lobe. The function of
that is vision, primarily vision. And then we move on to the side. We have what are called
the temporal lobe. Temporal lobe is going to be important in language. It's important
in hearing. It's also important in memory. We have a lot of memories in there. And so
each of these lobes have different functions that are associated with it. And hopefully
those little icons help you remember those functions. Now if we were to go inside the
parietal zone we'd find a really important part here. It's called the somatosensory cortex.
And that's where sensory information is coming into the brain. And then on the other side
of the lobe we have what's called the motor cortex. And so going way back to that worm,
we have information coming in, sensory information. And then we have motor output coming out.
And so that's going to be a point of integration where we get information in. Decide what we
want to do with it. And then send that message back out. Now if we were to look at that somatosensory
cortex and map it along the cerebral cortex, we would find that we dedicate huge amounts
of that brain surface area to things like your fingers, your tongue, your lips. In other
words we have way more neurons and way more sensory information coming in from your fingers
as opposed to, for example, your back. We don't have as much of it dedicated to that
on the back side. We could also functional MRIs and then even an operation to figure
out where a lot of these things are located, like speech and smell and hearing. But over
the future we're going to get really really good at figuring out specifically what are
all of the different parts of the brain. What are the nuclei? What do they do? And even
mapping it down to the level of the neuron. So how did you do? Do you remember those 17
different structures and their functions? Well it's time to review. So let's go through
it. What's this one at the bottom? Overall we call that the brainstem. Hopefully you
got that. What are the three parts of the brainstem though? Do you remember that? Could
you pause the video and then say what they are? Well starting from the bottom remember
we have the medulla oblongata. We then have the pons. And then we have the midbrain. So
that's going to be the structure and where it's found. Can you remember the two functions
of the brainstem? Two big things were, number one is to maintain breathing, heart rate,
digestion, swallowing. So these fundamental properties of life. But what's the second
one? Remember it's to sort information going up and down. What's behind that? What's that
structure called? That is the cerebellum. And so what's the cerebellum do? Remember
that's coordination, motor control and also motor memory. Do you remember what sits right
up above the brainstem? That is the thalamus. What's the thalamus do? Remember it sorts
information as it moves up to the upper parts of the cerebrum. What's below that? That is
the hypothalamus. Underneath that. What does that do? Remember that's homeostasis. It's
maintaining that internal body state. Do you remember what hangs off the bottom of that?
That is the posterior pituitary. Hopefully you're doing well so far. If we keep going
then, what is this upper portion of the brain called? We call that the cerebrum. Okay let's
keep going into the cerebrum the. So do you remember what's that connection between the
two hemispheres of the brain? We call that the corpus callosum. And do you remember what
we call those little nuclei that are found below that cerebrum? Those are called the
basal ganglia. And they're really important in motor control. And remember the corpus
callosum allows our hemispheres to connect. If we were to go up to the upper portion,
what do we call this, you know, highly folded upper portion of the cerebrum? That's called
the cerebral cortex. Do you remember what the front lobe is called? That was pretty
easy. That's called the frontal lobe. What about the yellow lobe right here? That's called
the parietal lobe. Do you remember what they do? Frontal lobe remember is executive or
boss like functions. And then parietal is going to be sensation of the environment.
What about at the end? Do you remember that? That's called the occipital. And then what
about the bottom? That's the temporal. Occipital remember is the location where we have vision.
And then temporal is going to be more language, hearing, memories are there. Now there are
two other parts in our lobe. So what do we call this area right here? And then this area
right here? Those are called the somatosensory cortex. Remember that takes in information,
makes sense of it. And then we have the motor cortex which is sending information out. So
those are those 17 structures. If you don't remember them you may want to watch the video
again. Maybe make some flashcards. But that's the brain. And I hope that was helpful.
Not cannabinoids specific, but since many of the papers posted here reference brain areas I thought this would bee good for some filler information.