MARIAN DIAMOND: Let's
start this morning
with our classification
of neurons.
We have a structural
classification, a functional
classification, and a
chemical classification.
You can use any of them when
you're talking about neurons.
So let's begin with our
structural classification.
We could have unipolar
cells, and these you'll
find primarily in the embryo.
We'll have just a
soma and a process.
Then we can have the pseudo
unipolar, which you've already
had, but we'll put it in
for completion's sake.
Pseudo unipolar.
And it will be found in
the dorsal root ganglia.
You'll see later that
that's your spinal ganglia.
The dorsal root ganglion.
And that, as we
showed previously,
you'll have two processes,
but one's stem to the cell,
to the soma, so we come
up with a single cell.
We had a peripheral process.
Why don't we just
call it a dendrite,
because it's myelinated.
So this is a rare exception,
this peripheral process
is myelinated, though it serves
the function of a dendrite
by bringing the
information into the soma.
And we call a process
that's on its way
to the CNS a central process.
Then we have bipolar cells.
Bipolar, which just
tells you then we're
going to have two processes.
A single soma.
So here, we'll have a
dendrite and an axon
taking the impulse away.
Taking the impulse in.
Where do we find bipolar cells?
We'll find them in the
retina, in your eye.
Guess Eye receptor, your retina.
We've already had
one group of them.
We had them in the
olfactory epithelium.
So a bipolar cell in the
olfactory, the olfactory nerve.
And we'll find them in
the auditory ganglion.
Auditory ganglion.
And then, by far, the
most of the nerve cells
will be multipolar So
multipolar is the most numerous.
So you only have,
really, two in the adult
to worry about, bipolar,
pseudo unipolar,
and then everything
else is multipolar.
Example, we'll give the
anterior horn cell again.
It's got its many poles.
Anterior horn cell.
We'll use all of these as
we're developing the functional
aspects of the nervous system.
So we're just gathering
up our building blocks.
Now then, we have our
functional classification, again
very simplistic, but
basic to get us started.
We'll have motor.
We'll have sensory.
And what's the third?
Interneuron, yes.
The interneuron.
So example of a motor
cell, we'll keep using it
because I hope 10 years
from now, you'll remember,
the anterior horn cell.
It's a motor cell.
It's what's allowing me to
write on the blackboard.
The anterior horn cell.
Then the spinal cord.
Sensory, example of sensory.
Once again, I'll
use the same one.
Your dorsal root ganglion.
Everything coming
into your spinal cord
passes through the
dorsal root ganglion.
These are also called spinal
ganglia, collectively.
And then we have
the interneuron.
So most neurons
are interneurons.
They will connect the
motor and the sensory.
So let's just say they're
between motor and sensory.
Sensory will be bringing
things into the CNS,
and then it goes
over to interneurons
until you want a
function, and then
the motor will take it out
and carry out the function.
So then we have
chemical classification.
And there are so many
chemicals associated
with the nervous
system now, we can't
begin to take a couple of
hours to give them to you.
So we'll just give
you three examples.
We have what are called
cholinergic neurons.
This will be chemical.
Cholinergic neurons.
So those who've had this
before, what's the transmitter?
STUDENT: Acetylcholine.
MARIAN DIAMOND:
Acetylcholine, right.
Acetylcholine.
We have adrenergic neurons.
What's the transmitter?
STUDENT: Adrenaline.
MARIAN DIAMOND: Adrenaline, yes.
Then let's just put in one more.
Let's put in a GABAergic.
GABAergic.
What's the neurotransmitter?
STUDENT: GABA.
MARIAN DIAMOND: GABA.
What's it stand for?
Gamma amino.
What's the next word?
STUDENT: Butyric.
MARIAN DIAMOND: Butyric.
Last word?
STUDENT: Acid.
MARIAN DIAMOND: Acid.
So that gives you examples.
As we said, there are many,
many more of these now.
So just a few more basic terms.
We've been using them, but
we haven't defined them.
What we call groups of neurons.
So groups of neurons of
like function inside the CNS
are called what?
STUDENT: Nuclei.
MARIAN DIAMOND: Nuclei.
Plural.
A nucleus, singular.
Or nuclei, plural.
So example, since we've
talked about it before,
we've talked about
the vagus nerve.
When we go to see where it's
originating from, part of it's
originating from the
dorsal motor nucleus of 10.
Dorsal motor nucleus of
the 10th cranial nerve.
And what's the name of
the 10th cranial nerve?
The vagus, right.
So we review and review, right?
Constantly get it from
different perspectives.
Now a group of nerve cell
bodies outside the CNS--
group Of nerve cell
bodies outside the CNS,
what do we call them?
STUDENT: The ganglia.
MARIAN DIAMOND: Ganglia.
Ganglion, singular,
and ganglia, plural.
So with this very
simplistic introduction,
we have some tools to
begin to work with.
Let's go now to the development
of the nervous system.
I give the development
because it will give you
the terminology, basically,
for the whole nervous system
at the beginning so
that we can use it
for more advanced functions.
So let's look at the development
of the nervous system.
And we all started with
a simple neural tube,
with our nervous system
starts as a simple tube.
This is called the
neural tube, and it
will have a central canal.
That's our central canal.
This is the head end, tail end.
This end is going
to form your brain.
So what's the rest of all
of this going to form?
STUDENT: Spinal cord.
MARIAN DIAMOND: The
spinal cord, sure.
Your whole CNS.
So the neural tube
develops the CNS.
Now, let's take a section
through this cranial end,
a cross-section of neural tube.
And our central
canal is changing.
Not just a simple
elongated tube.
It's taking on some shape here.
This now is our central canal.
And the central
canal in the head end
will form the
ventricles of the brain.
Form ventricles of brain.
So you have these chambers
inside the brain coming
from the original central canal.
We have a landmark here, the
so-called sulcus limitans,
because we can use it for
functional considerations.
So we'll put our landmark here.
Use lateral projections
of the central canal,
we call them the
sulcus limitans.
Sulcus limitans.
Limiting sulcus.
Then we can draw
an arbitrary line
across to the
periphery of our tube,
and everything
dorsal to our line
will go into what's
called the alar plate.
Alar plate.
The alar plate is sensory.
Ventral to our arbitrary line,
we'll have the basal plate.
So what's everything
in the basal plate?
STUDENT: Motor.
MARIAN DIAMOND: Motor.
What do they call the gene that
stimulates this arrangement?
STUDENT: Hodgkin's [INAUDIBLE]?
MARIAN DIAMOND: No.
Sonic hedgehog.
I didn't name it.
It's the gene that
affects the protein that
affects the alar and basal
sensory and motor plates.
So we're always
learning things new.
It's never always the same.
So now, with this, we want
to introduce a few more
terms here.
We need to have a roof plate.
And as you would
anticipate, the roof plate
is going to be up here.
So this gives us just
some basic divisions
that we'll work
with as we go along
if we take a section through
the area of the brain.
This will be, essentially,
the same in the spinal cord
initially, and then the brain
takes off and becomes so
much more elaborate.
So now, let's look at the
divisions of our neural tube.
As I've said before, the liver
only weighs seven pounds--
seven pounds.
The liver weighs three
pounds, and the brain
weighs three pounds.
And yet, the liver,
every single cell
is the same as every other cell.
So if I take some of my
liver here, or liver here,
or liver here, or liver
here, they all look the same.
They're phenomenal factories.
But the brain only
weighs three pounds.
If I take some here,
it'll look entirely
different from some
here or some here.
Everything's different.
That's the beauty of it.
That's the contrast.
That's the challenge.
So now, let's look at our
divisions of the neural tube.
We'll start very simple again.
Three main divisions
and down to our cord.
Use simple terms to start with.
Forebrain, midbrain,
and hindbrain.
Now we change the terminology,
put it into our old languages,
because the
literature does that,
so that you're familiar
with what they are.
I had lots of fun in an office
hour the other day [INAUDIBLE]
on things on the web and
working it out and explaining
all the terminology.
Because students are
beginning to get it.
Now they can begin
to talk about it.
So it's our forebrain,
it's the prosencephalon.
So encephalon means brain.
Pros means before.
So this is our forebrain.
Then we have the mesencephalon.
Mesencephalon, which
is our midbrain.
Heard of encephalitis,
haven't you?
Encephalitis,
inflammation of the brain.
And the hindbrain will now
be the rhombencephalon.
And the "rhomb" just deals
with the shape, a rhombus.
So it's the shape of
a rhombus in Greek.
We'll see when we look at
the ventricle how it changes.
Now then, these continue
to divide and give us
more divisions.
And then we'll look
at the derivatives
of each of these divisions.
The prosencephalon is going to
change into the telencephalon
and the diencephalon.
And the diencephalon.
It's worth the investment of
time to get familiar with these
to begin with.
Then you can handle things from
now on anywhere in the brain.
The mesencephalon
stays the same.
The rhombencephalon
divides in two,
just as did the prosencephalon.
So we have the metencephalon,
metencephalon and the,
which is the last one?
Do you know?
Myelencephalon.
Myelencephalon.
How do I remember their order?
Alphabetically.
S, T, and Y. So you can think
this is head end, tail end,
so S, T, E, just as
it is in the alphabet.
So it'll help you.
Because encephalon
is common to all.
So now what we're going
to do is take each one
and say a few words about it
so you get your orientation
of the total brain.
Because we'll be bringing
things in to part of it,
then take it on to another
part, to another part,
modifying the impulses.
So we need the basics,
basics, basics first.
Let's start now with
our myelencephalon.
What are the derivatives
of the myelencephalon.
Simple, because it's a very
basic part of your brain,
just adjacent to
the spinal cord.
I mean, this brain elaborates.
For early animals,
just had a spinal cord.
Information coming in,
going out, sort of reflex.
Then they add some more
cells to modify that.
So you put in a myelencephalon.
And then we go on,
and we're going
to see the cerebral cortex
is going to be way up here,
the highest, to
modify everything.
So our myelencephalon, the
structure we're going to form
will be the medulla.
I'll give you the full name
just so you've heard it.
Medulla oblong-- as soon
as I spell it right--
oblongata.
There we go.
We seldom use that.
But the kidneys have a medulla.
The adrenals have a medulla.
When people talk
about the medulla,
they have to say of the
brain, which structure they're
dealing with.
Your medulla is
only one inch long.
So it's a very small part
of your total brain, when
you picture it, just one inch.
It's one inch in
a chimpanzee, too.
So it hasn't evolved
that far up to the human.
So it has lots of functions in
that one inch, very dynamic.
As we said before,
it's essential to life,
but deals primarily--
it's got a center for
cardiovascular and respiratory
functions.
Where did I say the phrenic
nerve gets its control
for its rhythmic firing?
Pons and medulla.
This will be going down
for your phrenic nerve,
to keep you breathing.
Part of respiration center.
So there are lots of
cranial nerves that--
all of a sudden, I lost it.
No, it's there.
The cranial nerves
associated with the medulla
will be eight through 12.
The name of the
ventricle in the medulla
will be the fourth ventricle.
You have four ventricles.
We're starting at the bottom.
This is going to have
the fourth ventricle.
As soon as you start
reading your MRI scans,
you'll be alluding to these
all the time because they're
major landmarks.
So how does-- let
me just do this.
How does your neural tube
change as it forms the medulla?
You could say-- just put
your two hands together.
The palms represent the basal
and the fingers the alar.
Here's my sulcus
limitans in between.
When I come to the medulla,
it opens out like this.
So out here will be my alar.
My basal will still be my pons.
But what is important is what
happened to that roof plate.
We extended it tremendously.
So if we do this--
oh, our roof plate, I
guess, was pink, wasn't it?
So I-- So that's our roof plate.
So this is now alar plate, basal
plate, basal plate, alar plate,
and this is our roof plate.
When you study neuro
in detail, you'll
see how important this is.
And this is our
fourth ventricle.
So look at how it has changed.
I've seen people fail a PhD exam
for not being able to work out
what nuclei are in
various areas because they
didn't have their
fundamental development
of this area of the brain.
So this will give us a
very fundamental picture
of our medulla.
Let's move on up to
the metencephalon.
Two major derivatives
from the metencephalon.
Who knows those?
STUDENT: Cerebellum
and [INAUDIBLE]..
MARIAN DIAMOND: Pardon?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: Yes.
What are we coming up from?
The cerebellum and?
STUDENT: Pons.
MARIAN DIAMOND: Pons, right.
Derivatives will be the
cerebellum and the pons.
The cerebellum will
be on the dorsal side,
the pons on the ventral side.
So briefly, what are these.
Here's our medulla down here.
Our spinal cord.
And we've put in our cerebellum.
And on the ventral side,
we'll have the pons.
So now what in the
world are those?
The pons is a bridge.
That's what pons means.
We'll just expand it.
Here's our pons.
Here's our cerebellum.
What's it bridging?
It's a bridge of fibers
connecting the cerebral cortex,
which is up here,
the most highly
developed part of your brain.
From cerebral cortex down
to cerebellar cortex.
So I'll have pyramidal
cells way up here
in my cerebral cortex
that will have axons
that are going to go all
the way down, down, down,
down to my pons.
Masses of fibers coming down.
And then they will
synapse and send fibers
into the cerebellar cortex.
So major tracks for
the cerebral cortex
to talk to the
cerebellar cortex.
From cerebral cortex pyramidal
cells to cerebellar cortex.
And the connecting
link is the pons.
So that essentially gives
you pontine function.
Tremendous amount
of fibers coming in.
People are still
trying to learn why--
actually, this whole cortex
should have fibers going in.
What then is our
cerebellum doing for us?
Cerebellar functions.
We learn this early.
We'd have learned it, too,
balance and coordination.
And now, as we're beginning
to understand the connections
with the cerebral
cortex, it plays a role
in learning, fine movements.
I'll give an example
of a pianist.
See those hands.
Without a cerebellum,
that wouldn't be possible.
So with a pianist,
the cerebellum
is affecting both
hands and feet.
You've got those
pedals going as well.
Right?
Terribly important.
We've tested what
it means before.
So that gives us just
a basic introduction
to our metencephalon.
Let's move on to
the mesencephalon.
I'll move it over here.
We need to take the
mesencephalon-- maybe
if I give it some
dynamics for you.
The bullet that shot
President Kennedy
was lodged in his mesencephalon,
where they couldn't go in
for it, because you'll see
how it's not on the surface.
It wasn't anyplace
they could go for.
It was deep.
So the mesencephalon--
well, first,
let's look on a dorsal view.
So you know part of the--
you have to have
all these views.
We'll look at-- you'll see these
four rounded structures looking
down.
I'll show pictures of
these so you'll see them.
Let's just get the
basic arrangement now.
I think I'll take this off.
Since there are four
of them, they're
called the quadrigeminal bodies.
Quadrigeminal, four bodies.
Quadrigeminal Sham bodies.
And the two superior
ones are called the what?
Superior colliculi.
Superior.
Colliculi is just little
hill, because they
look like little bumps here.
Superior colliculi.
What do they do for you?
Visual motion.
Pick up that little
fly out there.
You hit your tennis
ball; you're watching it.
Visual motion.
The two inferior ones, what
are you going to call them?
STUDENT: Inferior colliculi.
MARIAN DIAMOND:
Inferior colliculi.
Sure, you can begin to name some
things that make sense, right?
Inferior colliculi.
They're part of your
auditory pathway.
You hear a loud
bang, and you jump.
An auditory reflex
response through
your inferior colliculi.
Very simplistic here.
Any one of these, you could
spend hours talking about.
All right.
Let's take now a--
what kind of section do I want?
Let's take a ventral view.
Ventral view.
And here, we'll have our
diencephalon up here.
We'll see these fiber tracks
coming down like this.
From down here, we have fibers
going in this direction,
and they're going out to a
structure that looks like this.
So we've just left
our metencephalon,
and we developed
these two structures.
So what are they?
These two structures, we just
developed in our metencephalon.
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: Pardon?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: Pons
and cerebellum, sure.
This is pons and cerebellum
from a ventral view.
Pons and cerebellum.
Just letting you know where
we are, because we've--
this was all metencephalon.
Now these fibers, here,
by the ventral surface
of our mesencephalon, so these
are called cerebral peduncles.
It'll come together.
It just takes time.
You're getting the parts.
We'll show how
they're connected.
And now we're going to
take a coronal section
of the mesencephalon.
And we'll see the
colliculi this way.
We'll take it on down this way.
And our central canal
has changed completely.
STUDENT: Professor?
MARIAN DIAMOND: I'm sorry.
STUDENT: What is D1
on the ventral view?
MARIAN DIAMOND: Oh, I'm sorry.
Diencephalon.
That was just abbreviation
for diencephalon.
Please ask.
All right.
Now, this is our central canal.
What do we call the central
canal in the mesencephalon?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: No.
That will be between
the diencephalon.
This is between the
fourth and the third.
Pardon?
STUDENT: Cerebral aqueduct.
MARIAN DIAMOND:
Cerebral aqueduct.
Good for you.
This is the cerebral aqueduct.
And this is where the central
canal is smallest in the brain.
So you get a tumor
in the midbrain,
and you can block your
cerebral aqueduct,
and you block all the flow of
CSF, cerebral spinal fluid,
that's in your ventricles.
So it's a crucial part.
We have a professor
who blocked it.
He'd come to class to show us.
They put a shunt in
to let the CSF run,
and they ran it under his
skin and took it down,
and it went into his
abdominal cavity.
The kids would
just come touch it.
They loved to touch
his head, but he was--
I mean, he'd sort of
retired, and everybody
had forgotten him.
But once he got that shunt,
he became a star in class.
So that was nice.
All right.
But it tells you how important
each one of these things
is, if one stops, to tell
you the dynamics of them.
And there we are.
And we didn't get
very far, did we?
We have lots to go.
But I think what I will
do while I have this,
just to make this
dynamic for you,
here are your cerebral
peduncles in this view.
They're down here.
This is coronal;
this is ventral.
This is ventral.
This was a ventral view.
But you took them across this
way, so they looked this way.
What are these, then?
Generic term for
them, because we
don't know what level we are?
Corpora quadrigemina, right?
You're on the dorsal surface.
So these are your
corpora quadrigemina.
And we're going to put in here--
we'll go to my slides--
a very important structure here.
We know more about
its function than just
about any place in the brain.
What's it called?
Substantia nigra.
The black substance.
We'll come back
to that next time.
But let's have our slides.
Substantia nigra.
If you see me sitting
here doing this,
it means I'm losing cells
in my substantia nigra.
Parkinson's disease.
We'll pick that up next time.
Let's review.
All right, here's our main
character, all fully formed,
just so you can see
what we're developing.
We take it through development,
so you get the stages.
Here's our one-inch medulla.
There's our cerebellum.
Our pons is going to
be tucked in here.
We haven't developed our
cerebral hemispheres,
but we'll come to them.
Next one.
This gives you a
chance to introspect.
How many times have
you introspected
into your own body?
When you brush your teeth
tonight, open your mouth,
look back, you'll
see are your uvula.
Then you'll have your
vertebral column.
And then imagine you
could go straight through,
and you'd be at
your spinal cord.
But then start to climb.
This is medulla.
This is cerebellum.
This is pons.
This is fourth ventricle.
Here are colliculi,
superior, inferior.
Here's our cerebral peduncle.
We only got that far.
We have all this yet to develop.
Next one.
This just shows our tube
for our prosencephalon,
mesencephalon, rhombencephalon.
And we're going to see a change
so that the prosencephalon is
going to form our
cerebral hemispheres.
Here's our diencephalon here.
The eyes will come out
from there, the retina.
Then this is our
future aqueduct.
It's big still.
Here's our fourth ventricle.
And we could see how it's
beginning to curve and change.
And the next one.
And this shows what it's--
this is hindbrain,
midbrain, forebrain.
What happens if this does not
close one month in the embryo?
You don't form a brain.
You have what's called
anencephaly, without a brain.
We've seen those when I take
my small class over to UCSF
to pathology, where the brain--
this did not close, obviously.
Yours closed one month in utero.
So we go over here.
Here's our medulla.
Here's our pons.
The cerebellum's
going to develop here.
Here's midbrain.
If you got this far,
here's our medulla.
Here's our pons.
Here's our cerebellum.
Here are the colliculi.
Then here are the
cerebral peduncles.
Pede Next one.
And this is just
putting it in the head
so you could see
cerebrum is going
to come from the telencephalon.
The diencephalon here.
The midbrain.
The cerebellum.
And beginning to develop, the
cerebellum, pons, medulla.
Already, you're getting
tired of hearing them.
There's superior colliculus,
inferior colliculus.
And there are your peduncles
on the ventral surface.
This was dorsal surface.
Next one.
And this is to show the brain
of an embryo at four months.
You see none of the fissures.
People say, well, when
does it begin to fold?
Well, you could say at
least you know you don't
have folds at four months.
So roughly around five months
in utero do you begin to fold,
because if you
didn't fold, you'd
have a brain that's 2
and 1/2 feet square.
So it's got to fit in this
skull to get through this birth
canal, so it folds.
But see, this just shows,
pons, cerebellum, medulla.
Midbrain's in here.
Next one.
Now we're looking
at a dorsal view.
Here's why it's called
a rhombencephalon.
This looks like a
rhomboid figure.
This is the roof of
the fourth ventricle.
Medulla's down here.
We've taken off the
cerebellum so we
can look down and see superior
colliculi, inferior colliculi.
We're going to go up into
thalamus, basal ganglia,
and the hemispheres.
And the next one.
And this shows the pons
from a ventral view.
Here's the pons.
You can see it's a real bridge
going into the cerebellum,
but it's connecting all the
areas of the cerebral cortex,
sending them all in,
because we know now
that the cerebellum
deals with learning.
We used to think it was
all of these muscle things.
It's very definitely
involved in our learning.
Here's your medulla.
And if we went deep in here,
we'd go on to our diencephalon.
Next time.
But this is mesencephalon.
Next one.
And this just shows
the fibers coming
from the cerebral cortex.
They've got to all
come in, funnel down.
When they pass
through here, this
would be your cerebral
peduncles coming in.
These fiber tracks have to go
clear down to my spinal cord
so I can be playing
with this pointer.
And the next one.
Next one, please.
This one just shows
the development
of an area, the insulo.
It's-- why some people
will be speaking in 131A.
It's in a very important
area for our speech.
And the next one.
Is that it?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: That's it.
Enjoy.
