Anatomy & Physiology Nervous System Part 2: Brain

Welcome back to www.educator.com.0000

This is the second set of lessons in the nervous system specifically the brain.0002

The adult brain is composed of a hundred billion neurons.0006

That is amazing to think about.0012

That is a lot of cells.0013

In the first few years of life you actually lose a lot of brain cells.0014

Think of it this a way, a baby’s brain is like a giant, untamed bush, and you do not need all of those branches and leaves to have the bush look nice and have purpose.0019

Imagine that a baby’s brain undergo a lot of pruning.0033

You clip unnecessary parts off that are not needed and become this nice functional shape with compartmentalized parts.0037

Proportionally baby’s brains have a lot more neurons than they need.0047

By the time you get into your adult life you are not making any neurons anymore.0053

The ones you have are the ones you are going to use until the end of your life.0060

The brain is part of the CNS.0065

The CNS unlike the peripheral nervous system contains the brain and the spinal cord.0067

It is central, brain and spinal cord going down your back to the middle.0076

In additions to neurons that make up a lot of brain.0080

You are also going to have neuroglia and these are specialized kinds of neurons that do not do just the regular signaling.0085

They just do not do the sensory and motor part of how the CNS works with your body.0094

The first one is oligodendrocytes.0100

Oligodendrocytes came up in the previous set of lessons regarding how neurons work.0102

Remember Schwann cells being those myelin sheets wrapping around neurons0107

in your peripheral nervous system that branch off from your spinal cord and brain.0112

Oligodendrocytes make the wrapping inside the CNS.0116

They help insulate and make salutatory conduction possible in the brain.0122

Astrocytes they maintain the blood vein barrier.0128

They have a lot of functions but I find this more intriguing that astrocytes looks like little stars that is why they are called astrocytes.0133

It looks like little beams extending from the cell body.0143

Astrocytes maintain the blood brain barrier.0151

It is duly enough your blood stream not everything in there is able to go to your brain.0155

It is a protective mechanism which is very important.0162

Some drugs introduced into the blood stream they stay out of the brain and they affect other organs and nerves outside of the CNS.0165

Other things can pass through.0174

One of the many other function of your blood brain barrier is protecting your brain from certain microbes or parasitic worms.0177

Interestingly enough there is a certain parasitic worm that I have heard of that has evolved the ability to dissolve the blood brain barriers.0185

It does end up inside a person’s brain if it gets into the body.0193

Microglia is another kind of neuroglia and think of microglia as like the trash compactors of the brain.0198

They are like a macrophage would be in your blood stream on either of cell debris.0211

They go around doing phagocytosis where they grab stuff outside of the cell.0218

Let us say it is waste that is accumulated, it might be some kind of foreign invader that should not be there.0223

They are cleaning up the trash in your CNS.0232

The appendemal cells you are going to find these in the ventricles which are the hollow cavities.0236

You will see those in the future presentations.0244

They are like little holes or cavities inside the brain and the central canal and other cavity you are going to find in the spinal cord.0247

You would find these cells adjacent to those spaces deep within the CNS because they help produce cerebral spinal fluid.0253

They help regulate and monitor it incase something goes wrong.0263

They do help produce more of it when needed or produce less of it if there are already plenty.0267

When it comes to brain development you start small.0272

If you look at a tiny embryo at a microscopic level you have a neural tube that first develops.0278

It is just very simple such the neurons are lined up and there is a hollow section in the middle.0288

It is like a tube.0295

That tube ends up getting little pockets and you can call them brain vesicles if you want.0296

At 3 weeks, you would see 3 main sections.0302

And up here is the anterior part towards the front and back here is the posterior part.0308

Up at the anterior part you would call this first bump, the procencephalon.0317

This word cephalon is going to be suffix or ending of all of these little areas.0327

Procen is up at the front.0337

The next part which I am going to do in green is going to be called the mesencephalon.0343

For the sake of time that is going to make it simpler I am just going to write meson.0351

It has cephalon after it of course.0356

Finally, at the posterior part this is the rombencephalon.0358

That is at 3 weeks.0370

Usually even before a woman knows she is pregnant this has already happened.0373

Procencephalon, mesencephalon, and rombencephalon.0377

At 6 weeks it gets a little bit more developed and expanded.0381

I am still going to use black for what happens to this anterior vesicle.0385

That becomes 2 areas that grows that is called the diencephalon and telancephalon.0390

Diencephalon and the telancephalon.0397

Next up you are going to see the telancephalon gets more to be a T.0406

It will expand on the sides here and if you use your imagination if this expands horizontally.0411

You could see how it looks like at the top of the T.0420

That is how I remember it.0422

The middle part called the mesencephalon just stays mesencephalon and it is a part of the adult brain.0423

This is not going to take on a different name as we go on to the parts of this brain tube.0434

The rombencephalon does become a couple of other areas and there is a trick to remembering these areas.0442

This is the mesencephalon, myencephalon, the way that I remember the back end of this is this is alphabetical.0451

Mesen and meten and then myen, S, T, and Y.0464

These are alphabetical order and that is how I remember them from the middle part to the posterior portion.0475

We are going to jump ahead way over at 40 weeks which is the approximate time that it takes for a baby to develop and be born.0481

You are going to see names that you probably have seen before having to do with brain anatomy.0491

The front gets a lot bigger.0497

The teloncephalon becomes the entire cerebrum.0503

The cerebrum in adult brain or a new born baby brain is that recognizable part with all the wrinkles on the surface.0510

That is lot of brain tissues.0515

This becomes the cerebrum.0517

This is still the diencephalon and later on in this presentation you will see the diencephalon is just deep to what is in the cerebrum.0522

The mesencephalon stays the same.0533

That is like an area between the diencephalon and the brain stem.0536

This is still the meson.0542

The metoncephalon becomes 2 parts that are in the inferior and posterior parts of the brain.0545

This becomes the pons and the cerebellum.0555

Cerebellum means mini or little brain in Latin because it is kind of a modified version of the word cerebrum.0562

We are using blue to this last part here becomes the medulla oblongata which is a major portion of the brain stem leading to your spinal cord.0572

By the time a baby is born a lot has come to this initial simple neural tube.0592

These brain vesicles become well established and enhanced as time goes on.0600

When we look at the cerebrum brain structure in an adult or a young kid, on the superficial part where you are looking at the top view down the cerebrum.0606

Here is the left and right hemisphere.0622

You are not going to see pink and green and blue.0625

This is color coded so you can see the different lobes which we are going to cover in a little bit.0628

On the outside is the grey matter.0633

It is darker.0636

If you cut into the brain and look deeper you are going to see a greater portion of white matter.0637

They grey matter tends to be more of the parts of neurons that are cell bodies.0642

What makes it grey is all the cell bodies compacted together, the nuclei that are slightly darker all of those together give it a slightly dark appearance.0648

On the other end, the white matter that tends to be deeper in the connecting parts that gets the part of the brain together and sibling each other that is more white.0657

The white comes from more axons.0666

Axons are those long parts that are the sibling parts of neurons to communicate with another neuron or another part of the body.0669

That white comes from the myelin sheets and in this case you are going to see a lot of those oligodendrocytes covering those parts of the axons.0676

That is why it has more white appearance.0686

Convolutions are the technical terms for the wrinkles.0688

People say that every time you learn something you are going to have a new wrinkle in your brain.0693

That is a simplification in a cartoon way to put it.0698

It is not like when you learn something new a wrinkle magically appears at that moment.0702

There is some truth to it because the more wrinkles you have the more neural tissue you are fitting in your skull.0707

Think about the surface of this having no wrinkles.0715

This means way less surface area.0718

You can compact a lot neural tissue by folding it up and having it folded in this very nice way.0720

As your brain grows and as you have neurons being made and other neurons dying off because they are not needed,0727

you are going to have wrinkles established and maintained.0739

A gyrus is basically a ridge or a bulge and we will color that in red.0744

Here is a gyrus right here that is a bulge and here is another bulge.0752

This gyrus here that extends in the red part that has a specific name called the pregyrus, because this line is called the central sulcus.0758

Because it is in the front of it they call it the pre central gyrus.0773

On the other hand this gyrus is called the post central gyrus because it is just behind the central sulcus.0777

Plural for gyrus is gyri.0791

A lobe is a more familiar term.0794

All of this green area is a lobe.0799

This specifically is a parietal lobe.0804

The red ones are the frontal lobes.0808

The blue ones are the occipital lobes.0810

You cannot see them in this image but the temporal lobes are below.0812

Like I have mentioned earlier, a sulcus is a deep wrinkle.0818

It is an obvious kind of sinking in.0827

If the ridges of the gyri in between them you can call that a sulcus.0835

It is a shallow groove.0842

It is not very deep that is a fissure.0844

A fissure is like a sulcus but way deeper like a ditch.0848

Here is one of the biggest fissures in the brain, this is called the longitudinal fissure.0855

That is the obvious barrier that separates the 2 sides of the cerebrum.0865

Finally the cerebral cortex.0869

The outer few millimeters of grey matter that is surrounding the cerebrum is called the cerebral cortex.0872

You have a lot of neurons there and a lot of mental processing.0880

That is where all the human things will recognize on a daily basis come from.0884

You have a lot of higher processes going on there at the cerebral cortex level.0890

When we look at the cerebrum as a whole it is the higher brain.0895

It is the most obvious part of brain anatomy when you look at it.0900

This image you are seeing here is an FMRI or the functional magnetic resonance imaging picture of my brain.0905

We are looking at my brain and this is a sagittal section so it is like we take a slice right through here and you could see my profile there.0915

Here is the cerebrum, all of that.0926

Here are the deeper parts.0930

We have mentioned diencephalon earlier, this is the diencephalon right in there.0932

Here is the pons, medulla, cerebellum.0939

All of this, the majority of the brain is the cerebrum.0943

This image is like you cut through that longitudinal fissure.0948

The corpus callosum which you are going to here about later, is this white strip.0952

That is hundreds of millions of neurons specifically axons because it is white that are connecting the 2 sides of the cerebrum.0958

The way that the left and right hemispheres communicate is through the white strip.0969

The cerebrum is divided into lobes as I have mentioned earlier.0973

The frontal lobe upfront and it is a large lobe.0977

The parietal it is off to the side up top.0980

The temporal lobes you cannot see them in this image they are on either side here.0984

If you are seeing the actual left side of the intact brain or the right side it might be visible.0991

The occipital lobe is tucked back here.0996

The frontal lobe this is a superior view and you could see they are quite significant.0999

You got the left side and the right side of the frontal lobe.1006

The frontal lobes are involved in intelligent thought, planning, sense of consequence, and rationalization.1009

These are the parts of the brain that make you intelligent.1016

If you are thinking and you are tapping here, you are tapping the part that is going to either help you solve the problem or come up with an intelligent answer.1020

The pre frontal cortex is the very front part of this frontal lobe and that is where most of that intelligent stuff is going on.1028

The example of phineas gage is a good way to think about what the frontal lobe does.1038

Phineas gage is a way rare worker back in the 1800 and there was a freak accident happen when they are laying down truck.1045

There is an explosion that having to do with getting stuff deep into the ground to hold the rail down and there was a missed fire.1053

This hot rod went through his head and did not hit any major arteries and missed what could have made him blind1061

and missed a lot of areas but went straight through the frontal lobe and at the top of his head.1070

He could bleed to death.1076

The heat from that thing that rock into his head cauterized and sealed shut blood vessels with all that heat.1079

I am sure he is in a hospital for a while but he lived.1086

This is the first time in recorded history that we know of in which somebody had just damaged their frontal lobe.1090

Phineas before the accident was a polite gentleman.1099

He showed up on time for work.1103

He had a great personality and people liked him.1105

After the accident, people call into that phineas was not Phineas anymore.1107

He tended to curse a lot more.1113

He tended to show up late at work.1116

Those things that made him who he was in terms of recognizing the responsibility,1118

having intellectual responses, caring, how his actions impacted other people, that was gone.1124

Think of the frontal lobe as something that made Phineas who he was.1132

Once that accident happened, he acted like an uncivilized person.1137

The primary motor cortex is tucked back at the posterior section.1143

The motor cortex here and here, that controls the muscles of your body.1151

Along this ridge you have sections that are devoted to moving the arms and fingers, and legs, torso.1162

The initiation of all of those movements comes from this ridge, in this region.1173

It is called pre central gyrus because it is front of the central sulcus.1180

The amazing thing is the amount of tissue that is devoted to your fingers and mouth is larger than you expect.1185

Your legs and your back are large proportionally in your body.1195

The actual sections of this primary motor cortex, initiation of the movement of the back and legs is significantly smaller than your fingers and your mouth.1200

Think about the precise movements you have to do with your fingers or the precise fingers you need to do with your lips, tongue and jaw, to speak.1211

And all the things you do with your hands.1220

There is a lot going on.1223

The amazing thing is that they made this neural maps showing how proportionally these parts1224

of the motor cortex controls the muscles in all the parts of your body.1232

Brocas’s area is an area associated with the part of the motor cortex that controls your mouth.1237

The reason why it is a little different is Broca’s area has to do with coordinating those mouth movements in a way that enables you to speak clearly.1245

Somebody with damage to Broca’s area can still make noise.1255

They can still say words but not in a coordinated way.1261

It varies on how badly it is damaged.1266

Some people with problems with the Broca’s area they cannot find the right words or they cannot speak words in a clear way.1269

That enables people to understand them.1278

Most people, this Broca’s area is concentrated in the left hemisphere rather than the right.1280

We will come to that later about how that impact certain situations.1288

The parietal lobes conversely streak for sensing.1292

This is the pre central gyrus which allows you to coordinate muscle movements but on the side of the central sulcus you have the primary somatosensory cortex.1300

That is right here.1318

Typically in this part here you have the ability to move parts of your arm,1321

just on the other side of that sulcus you have the parts that allows you to feel someone touching your arm.1331

All of the feelings you get, something touching your lip, head, back, whatever part of your body is being touched even inside of your body1341

that you have sense of, those signals are coming up into these parts of the parietal lobe.1352

Just like with the motor cortex, the proportion of these strips that has to do with sensing stuff on your hands and on your lips, those stimuli are much more obvious.1359

As humans, we do a lot of touching with our fingers so one can be able to tell one object is different from the other in a fine tune way.1376

The proportions for the hands and lips are greater than the actual size of them in our body.1387

There are interesting drawings made where they draw what would a person look like if we took1394

the somatosensory cortex and took the proportions in there and drew that individual.1401

Those drawings have a large face, huge lips, the hands are humongous, the feet are big too, and the torso, arms, and legs are puny.1407

If you see this person with large hands and large lips because those areas are the most sensitive.1420

While in the subject of hemispheres, it is true that the left side of the cerebrum communicates with the right side of the body and vice versa.1426

The right cerebrum communicates with the left side of the body.1439

Wernicke’s area is an interpretative area that is mostly the parietal lobe but it is slight in the temporal lobe as well.1444

If you wonder what this area does, it has to do with the temporal lobe a bit because the things you hear, those sound waves going to your ear,1456

the nerves connect what you hear to the brain and temporal lobe.1466

That is how you can hear it.1471

There is an area in the temporal lobe communicating with this part of the parietal lobe and1475

it is called Wernicke’s area named after the doctor who discovered it.1478

This area allows you to hear speech as something you can understand.1484

If you have damage to Wernicke’s area something that can result is you may still understand what the word sit means.1491

You may understand what the word here means.1499

But if somebody said sit here, the person with damage to the Wernicke’s area they would not understand what that meant when those 2 words together.1502

They cannot understand what words mean when they are strung together that is thanks to Wernicke’s area.1513

Imagination and dreaming has a lot to do with these lobes.1520

I have read that when they analyze Einstein’s brain, his parietal lobes were larger than the average person’s brain.1523

Maybe he had a genetic gift more than others in terms of understanding or visualizing how the universe works.1533

The parietal gives you a sense of where your body is in space which makes sense because if that somatosensory cortex or strip1542

is telling me what parts of my body is being stimulated, having my feet touch the ground and having my arms touching this table that I am at,1551

that has a lot to do with the parietal lobe.1564

Just my body realizing where my arms are and where my feet are.1566

If I do a head stand, that will send a different signal going up to my brain.1571

The temporal lobe is mainly for hearing but that is not all.1577

That is why you see auditory cortex here.1583

Here is the right temporal lobe and on the opposite side you are going to see a very similar lobe, the left temporal lobe.1586

The auditory cortex that is where the nerves from your ears go to.1591

This is the one part of the brain where it is not switched.1597

With my left hand feeling something is attached those signals are going up my right part of cerebral hemisphere1600

but when I hear something to my right ear it does not go to the side.1611

It just went straight to the right temporal lobe and same with the left ear.1615

The auditory association area allows you to make sense of what you are hearing.1619

That is communicating with Wernicke’s area.1626

Also, words have a meaning to them beyond just what the definition is.1630

There is the connotation of what a word means.1637

You can say a word in different ways and if you have damage to the auditory association area,1641

that infliction that people apply to different words may not make sense to you.1646

The olfactory cortex is the parts of the temporal lobe associated with smell.1654

We will talk more about smell in future lessons.1661

You can see that the olfactory tracks from the receptors that allows you to smell they go right through the temporal lobe.1662

They pass through right by the hippocampi.1672

Hippocampi have a lot to do with memory.1677

You may have heard that a lot of all the senses smell has the deepest connection to memory because there is truth to that.1680

The fact that the olfactory cortex goes right next to these parts of the brain that allow you to have those long term memories.1687

That is why when you smell freshly baked cookies you may think about your grandmother’s cookies that she made years ago.1695

It just triggers that response.1705

You may smell a perfume or cologne that reminds you of somebody immediately.1707

That is an example of how smells could trigger long term memories.1712

The occipital lobes are mainly for vision.1717

The visual cortex are the part of the back occipital lobe of the posterior part of the cerebrum that enables you to see.1722

The visual association area is what is allowing you to make sense of what you are seeing.1730

If you have damage to the visual association area, you may still able to see perfectly fine.1737

When I look at a sentence and I see the words B, E, D, I see bed as a part of the visual association area and I know that means bed.1746

Someone with damage to the association area they will be able to see the b, e, d, but not makes sense of what those all mean together.1759

It can be a terrible thing.1771

This is one of those horizontal sections or a transverse cross section through the cerebrum.1774

All of this yellow stuff is the parts of the occipital lobe that are functioning and using sugars and doing all of those action potentials to enable a person to see.1783

They have done this time and time again showing how these parts of the brain are associated with seeing and interpreting what you are seeing.1797

The corpus callosum is a strip of white matter like I have said before that connects the 2 parts of the cerebrum.1806

Here is a nice side view of what a corpus callosum is and here is a frontal view if you could look through the frontal lobes and see it.1812

You can that here is longitudinal fissure that ditch between the 2 hemispheres of the cerebrum.1821

You have a connection between the 2 with a lot of axons, hundreds of millions of axons that are allowing the left and right side to communicate.1828

Sometimes through surgeries doctor will actually cut through it.1840

One of the reason why is somebody who has epilepsy, seizures that come again and again.1845

A seizure is like out of control electrical storm in a person’s brain.1853

Seizures over the long run can do a lot of harm.1859

They will cut through that because somebody who gets a little seizure starting in the left side of the brain,1862

it will jump to the other side through the corpus callosum.1870

If you cut off the connection to prevent the seizure form jumping back and forth, and creating some harmful scenarios.1874

People who are epileptic if they cut through that you will get interesting effects because now it is not communicating as well.1882

You do not have the right and left hemispheres communicating.1891

Here is an example.1893

If somebody has cut their corpus callosum is holding a pen in their left hand, remember the left hand is communicating with the right hemisphere.1895

The parts of the brain that has to do with mating objects like making sense of words is more on the left side of your brain.1905

That has to do with this.1916

The left side of my brain is in the right hand.1918

A person who holds this in their left hand with a cut corpus callosum they will be able to know that they are holding this,1920

describe the object, but they will have trouble naming it.1928

The left hand does not have signals going up to that language part of the brain on the left side.1933

Conversely if they did not take that object and put it in the person’s hand on the right side, now this goes up to the left part.1939

Your language area tends to be more in the left side.1950

It is pen but if you ask them is this the same object you are holding in your left hand, the person will be probably tell you yes or no.1953

It is an interesting result from cutting the connection between the left and right sides of the cerebrum.1963

There is an interesting side note here, there is one other area in the very front called the anterior commissar.1971

That commissar connects a little bit of the front part of the cerebrum.1980

People who have a split corpus callosum you still have one little area in front of it where you can have some communication.1987

The seriousness of what I am talking about can vary from person to person.1994

The limbic system is the deep within the cerebrum.2000

It is on both sides, it is slightly on the left and slightly on the right.2006

It establish emotion, linking higher and lower brain functions, and helping in memory storage and retrieval.2011

The amygdale is a major part of it that tends to be in the deeper section.2018

This whole red stuff colored in that is the limbic system.2024

The amygdale plays a role in the fight or flight response which you are going to here more about in future lessons that I am going to give to you.2028

If you have damaged amygdale it is going to be hard or impossible for that person to connect emotion with a response.2035

For instance, if I step out into the street and out of the corner of my eye I see a car coming, that is going to initiate a very quick response in my body to back away.2046

Somebody who has a damaged amygdale and ahs trouble when that is happening.2061

Recognizing that something is threatening to you is thanks to the amygdale.2065

That is where the fight or flight response is going to come into play.2074

If something is threatening to you and the amygdale is connecting the response to the higher part of your brain that gets you to react effectively and keep yourself alive.2077

The cingulated gyrus or the cingulate cortex is on the top part here and this part of the limbic system assigns specific steps to certain emotions.2090

If you showed somebody a bunch of pictures of faces and they have a problem with they cingulated gyrus,2101

you could show the person a picture of a face that is like this.2109

You could tell that presumably you do not have a trouble with that part of the brain that I am giving a surprise or scared look.2113

The person who has damaged by looking at that part may not be able to tell you they are scared or surprised.2121

They may look with an open mouth and say I think they are hungry because they are missing that part that are enabling them to look at a face2129

and figure out what emotion that person is experiencing.2138

That is a part of being a social being.2143

As humans, we rely a lot on what other people are feeling or experiencing to inform us what is going on in our environment.2145

Limbic system is very important for keeping human beings alive.2151

A hippocampi is a part of the limbic system in the lower areas and it is like 2 nodules or areas deep within the temporal lobes named after the sea horse.2156

A hippocampus means a seahorse.2175

If you use your imagination maybe you will see that but here are the hippocampi and we are looking at the inferior view of the brain here.2177

Here is temporal lobe and you can see that they are concentrated in those sections.2187

The hippocampus has to do with getting memories.2191

It allows the consolidation of long term memories, the long synaptic term potentiation in a sense of time and space.2196

Long term synaptic potentiation that is a fancy term for saying that you are going to get a set of neurons in a connected path way stay in put2204

so that this one has the ability to stimulate this one permanently it maybe.2216

Long term memory is because you have a neural pathway established in your brain that has importance to.2222

If they have emotional importance, like importance for remembering your phone number or your address.2229

Those things that you remember for years, you can thank that hippocampus has enabled those parts of your brain to maintain neural pathways.2237

Short term memories, they form and they go.2249

If you ask me what I had for lunch on Tuesday of last week, I do not remember.2255

I could guess but chances are maybe I am wrong.2262

There was not a need for me to remember what I had for lunch on Tuesday last week.2266

Some people has a gift, have something special where they can remember everyday of their life and they call it a disorder.2270

It is somewhat a gift but the average person you will only going to be having long term memories maintained when they are needed.2280

A short term memory if you have a neural network established for conversation you had that was not of huge importance for someone.2287

After a day or two that conversation, the minor details of it you would not need that network anymore.2296

It can be re established for some other new experience that you just had.2304

The brain has a certain amount of what is called plasticity.2307

This is an important word that will come up later.2311

Plasticity meaning that the way the brain is arranged is not set in stone.2313

You can adjust what it is doing as your life changes over time.2322

That is very important.2326

Prior science from years ago, 30 to 40 years ago they thought that the adult brain was set in stone.2327

Research lately showed that is not true.2334

The brain has a great degree of plasticity.2337

Patient H.M is the best example I can give you on how the hippocampi work.2340

When he was alive for confidentiality reasons he was called H.M, his name was Henry Maleison.2347

Henry Maleison has passed away and that is why we know more about him now, he is one of the most studied patients in medical history.2357

Decades ago he had his hippocampi surgically removed in an operation because of issues about something in his brain.2367

The importance is that every other part of his brain is functioning properly but he is missing a hippocampus.2378

It is a great way to study what this does.2385

That is how we figure out what the other parts of the brain do.2388

If you damage one part and the rest of it is intact, you can figure out what is missing and what is different.2390

In patient H.M, with the doctors that studied him for years, he would not remember that.2395

They would come in weekly and study him and he has to be reintroduced to these people.2403

He can remember everything up to the surgery.2408

You can ask him about childhood memories, things about his family, he would remember those completely.2411

Once the hippocampi were removed, when it is no longer functional that prevented him from making long term memories that we take for granted.2418

The interesting is that memories has different addresses in the brain.2427

I do not want you think that he is completely incapable of long term memories.2434

It depends.2438

The amazing thing is that with the house that he lived in after the surgery, he was still being studied while he was living there with a caretaker.2439

If you ask him to design the floor plan he can design it exactly if you ask him to do it.2449

The theory behind that is even after his hippocampus was removed he had walked around that house for years everyday.2456

Something else in his brain was allowing him to remember that.2466

Another interesting thing about that is I have heard a story about H.M, that the doctors went in one day2472

and shook his hand and introduced themselves as if he never seen them before.2483

A few days later the doctors came back in, shake his hand, and now one of them has shaking buzzers on their hand.2490

The 41th doctor shakes his hand and introduce himself and shocks him.2499

He is disturbed by that and they had a good laugh afterwards.2503

You would think that he would not remember that at all.2508

The next time the doctors come in, the last doctor that walks into the room has the buzzer in his hand.2511

He meets the first 3 doctors and then the 4th one comes and he hesitated a little bit in meeting this person.2517

Maybe some other part of his limbic system had allow him to retain some kind of emotional response to that individual.2527

This is going to show you that he is very complicated.2535

Even he is missing a hippocampus, it does not mean that all of your long term memories are not going to happen anymore.2539

The majority is it is going to be affected.2546

The basal nuclei has to do with the coordination of learned movements.2549

It is maintaining those learned movements over time rather than initiating it.2555

For instance, when you walk the precise movements of your arms and thighs, you do not have to think about it consciously.2559

When you walk your arms just sway back and forth, opposite when your left arms move forward your right leg tends to move forward and so on.2567

We did not put conscious thought into it but you can thank the basal nuclei.2575

These regions deep within the brain and you could see they are concentrated in the white matter or the signaling parts2580

which makes sense because they are signaling these coordinated movements of your arms and legs while walking.2588

Parts of the basal nuclei are inhibited by dopamine.2593

I brought this up earlier in the previous lesson that if dopamine is the neurotransmitter that is turning off some of these parts.2599

If you do not have as much dopamine being released as you should, you can get some uncoordinated movements making it hard to make precise motions.2605

The olfactory bulbs/tracts have to do with smelling.2614

This is a great image from Grey’s anatomy.2620

We are looking at an inferior diagram of the brain.2623

These little red parts outlined there, they look like little white strands.2626

They are very obvious when you turn it underneath.2635

You can see these 2 parts and they have to do with receiving smells from the olfactory receptor cells and bringing those parts into the brain.2638

These are the only nerves that go directly into the cerebrum rather than the diencephalon or brain stem.2650

If you think about the nerves coming from your arms, legs, and eyes, they go through relay stations on the way up to your higher brain.2656

The exception is this olfactory tracts.2667

They are just inferior to the pre frontal cortex like I have mentioned before, the very front part of the frontal lobe is called the pre frontal cortex.2670

The ventricles of the brain are basically cavities.2680

If you heard that the ventricles of the heart, the hollow areas within the heart is the same kind of structure in terms of white disk.2685

These are hollow cavities deep within the brain.2692

We would not call this a ventricle.2696

If you remember this is the longitudinal fissure that you can see very easily when you look down on the brain from a superior view.2698

This is a ventricle and this is a ventricle.2706

This is one of the frontal or coronal sections straight through the cerebrum.2710

This is a good view.2716

You can see parts of the ventricles here.2718

This is a transverse horizontal section.2721

What do these cavities do?2724

They have to do with generating and circulating the CSF also called the cerebral spinal fluid.2726

There is a kind of cell known as the choroid plexus that is adjacent to the ventricles.2735

Remember the appendimle cells they have to do with making CSF and regulating it.2745

These ventricles those cavities within the brain gets CSF in there and they circulate that around the outside of the brain2756

and outside of the spinal cord as well as in the central canal.2766

What does the CSF do?2772

Why is it important?2774

It has a lot to do with protecting the CNS and helping to regulate the amount of gases coming in and out, the waste leaving, nutrients coming in,2775

so that the health of CSF impacts circulation in and out of the brain.2786

It is very important.2792

The diencephalon is deeper than the cerebrum.2793

We are done with the cerebrum.2801

That was a lot of slides.2803

The cerebrum is very complicated.2805

If you go just deep to that, there are 2 regions, the thalamus and the hypothalamus.2807

Hypo meaning below the thalamus.2812

The thalamus is a relay station.2815

It brings sensory information up to the cerebral cortex in a coordinated fashion.2817

Like I have said earlier, the majority of the nerves coming into the CNS they have to go through the thalamus on their way up.2822

A classic example of that is the optic nerve.2830

The hypothalamus which is directly below the thalamus has a lot of roles.2833

It is just above the pituitary gland and you are going to see this more obviously in future lessons.2839

If you took a cross section of the brain, there is a little thing that looks like a pea that is hanging from the base.2844

That is the pituitary.2849

The hypothalamus is what is right above it.2850

Feeding reflexes, salivating.2853

A baby making certain motions during breast feeding has to do with the hypothalamus initiating those things.2855

The feeding center and thirst center, you getting hungry and thirsty.2866

The signals from the brain that have to do with that come from the hypothalamus.2872

Had to do with sleep versus being awake.2879

Typically for most humans when the sun goes down after that you tend to get more tired, the exception being if you work at night shift.2882

For the average human being circuiting rhythms has to do with signals from the environment telling your brain it is sleepy time.2892

When the sun comes up, it is time to wake up.2902

The regulations of the circuiting rhythm that have to do with changing your conscious state that is from the hypothalamus.2905

Communication with the pituitary gland.2914

If you remember me saying that the pituitary gland is like a little pea shaped gland hanging right below the hypothalamus.2915

A lot of people refer to the hypothalamus as the master of the endocrine gland.2921

It is the big head huncher.2925

The pituitary gland is second in command.2927

The hypothalamus tells the pituitary gland to secrete certain hormones at certain times.2930

The pituitary glands impacts the other endocrine glands and causes them to release hormones.2936

The pituitary glands causes other organs be regulated.2942

For instance, the pituitary gland secretes growth hormone.2946

Making your bones elongate in a proper way throughout your adolescence that is regulated via the hypothalamus and pituitary gland.2950

Subconscious skeletal muscle control are all those movements you do that you do not have to think about, you can thank the hypothalamus.2960

The pineal gland is the final part of the diencephalon and it is in the anterior portion of this area.2968

It is like a smaller pea.2974

It is a similarly looking structure but not hanging in the brain, it is tucked in the back.2978

This has to do with secreting melatonin.2984

Melatonin is a neurotransmitter that puts you to sleep.2986

There are lots of studies done with people taking melatonin pills when they go to a plane to make them go to sleep.2993

I studied that it has to do with the placebo effect of that suggesting that the average person who takes a melatonin supplement did not need it.3001

The melatonin in your brain is enough to put you to sleep naturally.3012

The mesencephalon is just posterior/inferior to the diencephalon.3016

Here in this cross section this is another sagittal cross section straight to the corpus callosum.3026

You could see this end is the mesencephalon.3034

It has a lot to do with processing visual and auditory data that comes in from the eyes and ears.3037

Your reflexive somatic motor responses are generated here.3043

That is a fancy terminology for when you hear a sound or see something at the corner of your eye and react.3047

If I heard something over there and did this, without me having to think about it, that is because of the mesencephalon.3054

If your eyeballs move too and there is actually something has a lot to do with the mesencephalon.3060

The maintaining of consciousness comes from this area.3066

I am using my mesencephalon right now.3071

The pons, it is the same image as before.3073

The pons is this bulge right here.3079

It is just below or inferior to the mesencephalon and just anterior or in front of the rest of the brain stem.3083

These links the cerebellum which is right back here with the other parts of the spinal cord.3093

Considering its proximity there it makes sense that it would do that.3101

The pons has a lot to do with getting communication to the higher brain and lower parts of the brain.3105

It plays a significant role in dreaming.3111

The medulla oblongata is the majority of the brain stem.3115

You can see that it is the inferior portion just below the pons.3122

Here is a side view.3129

Here is a frontal view and anterior view.3131

It contains the cardiovascular, vasomotor, and respiratory centers.3135

Damage to the medulla oblongata often result in fatality because your heart rate is controlled by the cardiovascular center.3141

The vasomotor center controls your blood pressure, the expanding and contracting of your arteries and the respiratory center.3152

You do not have to think to breath.3160

If we have to think every time we have to breathe our life will be a little shorter as human.3162

Thankfully you can sit or go running and that not have to think about breathing.3169

You are just going to automatically do it.3175

Now that talking about breathing you are probably thinking about every exhalation and inhalation that you are taking.3176

Without the medulla oblongata functioning properly, the heart, blood vessels, lung expansion and reduction is not going to happen.3184

That is needed to keep you alive.3193

The reticula formation is a part of the medulla oblongata that helps regulate vital autonomic functions.3196

Those are going to come more into play when we talk about the branches of the nervous system3203

in future lessons and how the endocrine system also controls the fight or flight response.3208

Numerous nerves ascend go into the brain through here which makes sense.3213

This is the spot that signals have to go through from the spinal cord.3220

If you continue this image down, the medulla oblongata transitions into the spinal cord.3226

The signals come from the lower parts of your body have to go through this area to get up into the brain.3234

The cerebellum which means little brain in Latin is inferior to the occipital lobe.3241

You can see that here is the occipital lobe and it is below it.3248

It is posterior behind the pons and medulla.3251

I love this image here on the right because when you cut it in half you can see this cool design that almost look like branches of tree.3255

That is known as the arbor vitae which is Latin for tree of life and that is made up of white matter.3265

It is a very distinguishing part of the cerebellum.3273

If you remember from the previous lesson on neurons the image of neurons with all those dendrites and looks like the most branching of trees you could have.3276

You have a lot of those kinds of neurons in here.3286

It is all about coordination of your motor function and balance.3290

If you are good in a video game and without consciously thinking about it anymore, just automatically move the aero buttons3295

and the other buttons on the side to do all the activities in a video game.3307

If you have this skeletal muscle memory of doing certain action to get to the next level, you can thank your cerebellum.3311

If you are able to play a piano or play guitar with 2 hands and get to the point where you can play3321

a piece of music without even having to think about it.3329

It is just your fingers know where to go, you can thank the cerebellum for that.3332

The meninges are wrappings around the brain and the spinal cord.3337

It envelops, wraps around the CNS as a whole.3346

It is around the superficial portion that helps insulate the CNS and helps regulate blood flow.3351

Sometimes you will get what is called meningitis which I will mention again in a little bit.3359

That is an infection of these meninges.3365

The problem with that is if we zoom in to where the meninges are, here is what it looks like to be the parietal bone or frontal bone.3368

Just deep to it you have these membranes that are right in between the skull and the brain.3378

If you get a bacteria, virus, fungus, in this part of your head, your immune response to that being there is going to create inflammation or swelling.3385

The problem with swelling here is that your skull is not going to budge.3397

The swelling in this region is going to be pushing on your cerebral cortex.3401

That is going to be potentially fatal.3406

Meningitis is one of those things that have to be treated as soon as possible.3408

Besides the infections, the meninges are very important.3412

The singular version of this word is not often used but they say meninx but I hear the word meninges a lot more because we are talking about them as a whole.3417

There are several layers.3430

The duramater is the one that is just adjacent to the inside of the skull.3432

Right under the cranium you got this area called the duramater.3439

You have another layer just deep to that.3445

There is a little pocket in between the 2 layers of the duramater that is where the CSF is going to be.3449

The fore wing of that CSF around the brain and spinal cord is going to be within that duramater.3455

We have this area called the arachnoid between the duramater and the piamater is right on top of the cerebral cortex.3461

That is the part of the meninges that is directly adjacent to that grey matter of the cerebrum.3471

The way that I keep them straight is I think of them in alphabetical order.3476

Duramater D comes before P, I think from top to bottom, most superior or most superficial to deep, the 2 layers of duramater and then the piamater.3482

Remember that duramater has 2 layers.3497

D for di meaning 2 or whatever works.3500

These are the layers of the meninges.3506

They are protecting the CNS and help regulate blood flow.3510

Some brain disorders and conditions.3513

Like I have mentioned previously seizures are most common in people with epilepsy but a seizure can happen in anyone.3517

Not always know about the origination of seizures but there are a lot of studies being done.3524

It is like an electrical storm in the brain and the reason why some of the seizure usually ends up on the ground convulsing is3529

because it is stimulating so many parts of the brain that are typically regulating motor control that is out of control.3539

You do not have that coordinated inhibition and excitation of those muscles.3547

It ends up creating a situation when they are convulsing.3552

A piece of advice, do not prevent someone from swallowing their tongue if they are having a seizure.3559

When a seizure is happening because of that uncoordinated movement sometimes the tongue can3566

get in the way of the respiratory passageways but that is not what as common as you think.3573

People who have tried to prevent someone from swallowing their tongue or they are seizing have got their fingers bitten off.3579

That is not something you do want to put your fingers in a person’s mouth who3586

cannot control consciously their skeletal muscle movements because they might be biting down.3591

What you should do is find a way get a pillow and get something soft or just hold their head, prevent their head from hitting something hard.3595

When the seizure is done assess how they are doing.3604

Concussions are fairly common especially in sports that involved collisions.3608

Car accidents are another way for someone to get a concussion but anytime that your head hits something very hard3617

or something hits your head very hard, it can cause a brain bruise.3624

That is basically where the concussion is.3628

It has to do with your head being hit so hard that all of the meninges cushioning your brain,3630

the CSF being a nice buffer between your brain and the inside of your cranial cavity.3638

Your brain physically hitting to your skull and usually it is just damaged on the superficial parts of the brain that someone has recover from.3645

Enough concussions over time can cause permanent damage.3655

Meningitis I already mentioned before either bacteria, viruses, or fungi can actually infect your meninges.3659

The signs of meningitis happening is fever, sense of pain up here, it is like a bad headache, confusion like not a sense of what is going on.3670

The other one is if a person has trouble doing this, if they get a lot of pain from moving their head down to their chest.3683

It is because they are stretching part of the meninges and that activity will cause a lot of pain.3691

If those signs are happening go to the ER.3697

It is better to be safe than sorry.3700

Stroke also known as cerebral vascular accident has to do when arteries going up to the brain get clogged.3701

Depending on what artery get clogged or arterioles that is going to cut off blood flow to a certain part of the brain.3711

Strokes can be fatal and sometimes they are not.3718

It depends.3722

Signs of someone has a stroke is you get disagreement of what the sides of your body are doing or what it is able to do.3724

A stroke is going to happen on the right or left side.3732

It is very rare that you have two strokes on the left and right side simultaneously.3735

Let us say a person has stroke in their left hemisphere that is going to affect the right side of their body.3740

If you ask the person to smile and they will be able to lift up this part of the mouth that is a sign they has a stroke.3745

If you ask a person to lift up both of their arms, if they cannot lift this arm quite as well that is another sign they had a stroke.3753

You should take them to the hospital.3761

Hemorrhage this is not just in the brain but you can get hemorrhage in the brain, it is basically internal bleeding.3763

You can get hemorrhage in the surface of the brain, have hemorrhage within the brain, depending on how bad they are, they can be fatal.3770

Surgeries are required to get rid of bleeding.3777

Aphasia is any time that a person has the inability to speak or read at a normal level and that has to do3783

with underdevelopment or damage of those regions because of an accident.3792

Related to that is dyslexia.3799

I have heard that it affects as much as 15% of children and it still affects adults too.3801

Dyslexia is not something that is incurable.3809

It is something that someone can get over but it has to do with reading and the words is not completely making sense as it does in a normal reader.3814

Let us say the person is looking at the word pie, they may actually see eip when they read it.3822

That is going to create some issues with understanding.3833

There are therapies that a person can do to get to the point where they see this as they should.3837

It is something that with work you can conquer.3842

Disconnection syndrome is result of cutting through the corpus callosum, having the left and right hemispheres not being communication.3849

Having that disagreement of what the left and right sides of the body are telling the person.3859

Like I have mentioned earlier, there is a small area anteriorly connecting parts of the frontal lobes that can still be in communication.3866

The majority of that communication is in the corpus callosum.3876

Hydrocephalus literally means water on the brain.3879

This is most common in infants if they are not regulating the amount of CSF within the brain and the outside of the brain and spinal cord,3883

if they are producing way too much of it you can get the swelling.3892

It is almost looking that they head is ballooning.3896

That is most common in infant because if you say the skeletal system lessons, those cranial bones are not completely fused yet.3899

There is little bit of wiggle room and that build of that CSF looks like the head is ballooning and they can be fatal if not treated.3909

Parkinson’s disease has to do with coordinated motor stimulation and has to do a little bit with dopamine imbalance.3916

There is not a complete cure yet but I believe on day there would be a cure for Parkinson’s because it is probably more than dopamine.3930

There are genetic factors and environmental factors that have to do with Parkinson’s disease and its onset.3939

Alzheimer disease I have heard people mispronounce this and say old timers, it is Alzheimer and it is named after a doctor that researched it for many years.3948

Alzheimer disease here is a picture that shows you what it looks like.3959

Here is a healthy brain where those coronal or frontal section through the cerebrum and this is severe AD or Alzheimer disease.3964

You can see that there is a lot of deterioration.3973

It is going to affect the hippocampi and that is why somebody with severe AD is going to have memory problems or sense that maybe they are in a previous time.3976

One of my great grandparents have AD when we would talk to her she would think a lot about previous times as if she was still in the moment.3989

She would look at relatives that she knew and say you remind me of this person as if she was stuck in a previous time.4000

The cerebral cortex as you could see the outsides of the cerebrum are severely impacted.4009

You can see it is wearing a way of a lot of that grey matter and that is going to gradually incapacitate somebody4016

to the point where they are not going to be able to take care of themselves.4023

There is a lot of research in the AD identifying factors that making someone to likely get it.4026

Once again genetics has something to do with it but there are certain environmental factors that make it more likely for one person or another to get it.4033

As you age, the chances of AD coming into play increase.4041

If you look at a population of people who are in their 60’s, they are less likely to get it.4047

Some people in 60’s can get it.4053

If you look at a population of 80’s or 90’s the incidence of AD goes up significantly.4055

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