MARIAN DIAMOND:
Now, I thought that
with our brief survey
of the human body
that it would be a
shame not to spend
some time on the cells
that built the Golden Gate
Bridge, that built the
pyramids, that built the Palm
Pilot, if you want to take
an extensive view of what
these little masses
of protoplasm can do.
So I'm going to
very briefly cover
the two main cells in
your cerebral cortex
that are responsible for
all of your behavior.
So there are two types
that are most common.
These are cerebral
cortical cells.
The two most common will
be the pyramidal cells--
do you understand why I
took my choice of words
as to what we're respecting
in society, the pyramids--
pyramidal and stellate cells.
The pyramidal are
the most common.
And as the name implies,
they're pyramid shaped.
And the stellate, as the name
implies, they're star shaped.
When you get pictures
of them from the slides,
they don't always
have a whole cell.
You get parts, but roughly
looking something like that,
with a short axon.
The pyramidal cell
has a long axon.
So long axon neurons are
classified as Golgi Type 1.
You'll see that
in the literature.
Golgi Type 1 with a long axon.
In contrast, stellate cells are
Golgi Type 2 with short axons.
In fact, sometimes these are
called local circuit neurons
because they have such short
axons carrying on functions
within the local circuit.
But what I want to
elaborate a little bit
to show you the
dynamics of dendrites,
we'll talk about the dendrites
on the pyramidal cell.
And first, we'll have
the apical dendrite.
So it means that
it's just coming
from the apex of the pyramid.
Coming up here, this
is my apical dendrite.
Coming from the apical dendrite,
we'll have oblique dendrites.
Oblique dendrites.
And these will be coming off
obliquely from the apical,
somewhat like this.
So we'll just put two for
our oblique dendrites.
And three then, are
the basal dendrites.
Basal dendrites.
Coming from the base of the
triangle or the pyramid,
they'll have first
a primary, then
it'll branch to a secondary,
tertiary, and so forth,
and can keep on going
for many branches.
So these represent
basal dendrites.
Maybe distinguish them from
the soma by making this solid.
But it's interesting because
each set of dendrites
receives a different input.
So the apical dendrites are
receiving subcortical axons.
The oblique dendrites
will be receiving
from the opposite hemisphere,
the contralateral hemisphere.
Opposite or
contralateral hemisphere.
And the basal dendrites will
receive intracortical input.
Intracortical.
What's the term
for the same side?
Have you heard it?
Ipsilateral.
So this would be the
ipsilateral side.
Intracortical on ipsilateral,
which is same side.
So when one is measuring
dendrites and looking
for changes with
the environment,
it's fascinating when you
find only one set of dendrites
is responding.
We found that the basal
dendrites in our work
were responding
most, and that was
most exciting because
the intracortical play is
of the highest kind.
So it gives you an idea of why
one studies these dendrites.
Now, one type of cell which
is called a Betz cell.
It's the largest neuron.
We gave you two
examples of the largest.
We gave you an
anterior horn cell.
So an anterior horn cell and
the Betz cell are the largest.
Let's put them together.
Largest neurons.
Where do we find the Betz cell?
It's a pyramidal cell an
area IV, layer V. Betz cell,
pyramidal cell in
layer V, Area IV.
So can you see it?
Can you see where your
area IV is in your brain?
You know you've got six
layers to the cerebral cortex,
and you'll see these big ones.
So when you see them,
you won't think that this
is due to some abnormality.
They are normal.
There are few of them.
They inhibit
anti-gravity muscles.
Just to give you a little bit
about them, we'll stop there.
But it lets you know they
have a special function.
So that's just essentially
all we have time for
to give you the brief
introduction of two
types of cells.
Now, we want to spend the
rest of the time dealing
with the eye.
This phenomenal structure that's
designed to bring in light,
to stimulate nerve
cells, to give you
images of the outside world.
How many of your cranial nerves
are related to eye functions?
Half of your cranial nerves.
Six out of twelve are
related to the eye.
So two-fold purpose
in giving these.
So the first one then will
be the second cranial nerve.
What's its name?
STUDENT: Optic nerve.
MARIAN DIAMOND: Optic nerve.
So we know its
function is vision.
What's the third cranial nerve?
STUDENT: Ocular motor.
MARIAN DIAMOND: Ocular motor.
So it's going to the
levator palpebrae
to raise your eyelid,
if you remember.
And four of the six
extraocular eye muscles.
So we'll have a superior rectus,
we'll have an inferior rectus,
and we'll have a medial rectus,
all supplied by the third.
As well as the inferior oblique.
Then we have the
fourth cranial nerve.
What's its name?
Come on.
What its name?
STUDENT: Trochlear.
MARIAN DIAMOND: Thank you.
What's it do?
STUDENT: It's a pulling muscle.
MARIAN DIAMOND: It's
a pulling muscle.
Good for you.
So you remembered trochlear
and remembered it's a pulley,
but where is it going?
What muscle is this?
What one's left out?
STUDENT: Superior oblique?
MARIAN DIAMOND:
Superior oblique.
Right.
Process of elimination.
You can learn by
that if nothing else.
Superior oblique.
And then we get five.
What's the name of five?
Trigeminal.
What's it doing for your eye?
What's it doing for the face?
What's it doing for your nasal
cavity and your oral cavity?
It's sensory, right.
It's sensory.
You get a piece of dust on your
cornea, that's fifth nerve.
So it's sensory to the eye.
We'll put cornea
because that's what
causes us most of our problems,
getting something in our eye
and it hurts and it itches.
Sixth nerve, what's it called?
STUDENT: Abducens.
MARIAN DIAMOND: Abducens.
Do you remember what it does?
What muscle is it going to?
STUDENT: Lateral rectus.
MARIAN DIAMOND:
Lateral rectus, right.
Let's see, we've
got two, four, six.
We need one more, seven.
What's seven doing for your eye?
You've opened your eye, how
are you going to close it?
Circular.
Every time you blink.
What is it?
STUDENT: Orbicularis oculi.
MARIAN DIAMOND:
Orbicularis oculi.
See why I review and review?
It's up there somewhere but you
don't know how to retrieve it.
And that's what we've got to
train you, on how to retrieve.
All right, so this is facial.
And it was going to
your orbicularis oculi.
So you can close your eye.
Now, I think there's just
one statement in here
that I think is
important that I read,
that 70% of the receptors in
your body are in your eye.
Just to make the
dynamics of this.
Here we have all kinds of
receptors throughout your skin.
But with the receptors in your
eye, it's 70% were in the eye.
What part of your brain stem
does your eye develop from?
Do you think it's
going to be hindbrain?
No.
MIdbrain?
No.
What's left?
Forebrain.
Good.
We can work up to it.
It sounds elementary, but
when you don't know it,
we've got to review.
So yes, it's going to come
from the diencephalon.
The more you remember
your embryology,
the more you'll remember
your neurology of the brain.
So let's see, we've
got a cross-section
of the diencephalon.
We have our central canal.
And we have, at the floor
of the diencephalon,
the migration of nerve
cells that will form
what's called the optic cup.
Two eyes.
So the optic cup has two parts.
We have the pigmented retina
and we have the neural retina.
Pigmented is the outer portion.
And the neural
portion, the inner.
The pigmented layer prevents
the diffusion of light
to adjacent rods and cones.
Prevents diffusion of light
to adjacent rods and cones.
So let's now develop our
neural retina briefly.
You could spend a
whole semester on it
just to introduce the basics.
And this will be anterior.
This will be our neural retina.
You've probably had
this in basic biology.
We'll start with, the
light is coming through.
It comes all the way
through the retina
to the lowest level of cells.
And the first layer will
be the rods and cones.
And these are your
photoreceptors.
How many rods do you have?
About a hundred million.
How many cones?
About 7 million.
Why do you need rods?
What do they do for you?
STUDENT: Night vision.
MARIAN DIAMOND: Pardon?
STUDENT: Night vision.
MARIAN DIAMOND: Night vision.
Dim vision, right.
Night vision or dim vision.
Why do you have cones?
Acute vision and color vision.
How do you remember
which is which?
Cones begins with a C, acute
a C, and color a C. All right?
Just because, frequently,
it makes it easier for you.
Now, the next layer of cells
will be the horizontal cells.
And what are horizontal
cells doing for you?
STUDENT: Lateral integration.
MARIAN DIAMOND:
Lateral integration.
So I have to make room here.
Horizontal cells to
lateral integration.
And then we have bipolar cells.
And they're carrying the
impulse on up to the next layer,
which is four.
So amacrine cells.
What do amacrine cells do?
They're again,
lateral integration.
What makes them different?
What's amacrine mean?
They have no axon.
A, without.
And we're working our
way up to the last layer.
What is it?
STUDENT: Ganglion cells.
MARIAN DIAMOND:
The ganglion cells.
Right.
And their axons now will
form the optic nerve.
Your second cranial nerve.
But how do they do
that, and what happens,
and why does the light have to
come all the way through all
these layers to
go out eventually?
Why don't we just have the
rods and cones catch it first
and then the ganglion
cells come out?
Good question.
We'll wait for our
evolutionists to tell us.
But the axons from
these cells now
are going to collectively come
out and go back to the brain.
Giving an example.
And as they pass
through then the retina,
we call the area the optic disc.
What's another term
for the optic disc?
STUDENT: Blind spot.
MARIAN DIAMOND: The
blind spot, because you
can see there are no
photoreceptors here.
It's just neural tissue
passing through nerve fibers.
So this is our blind spot.
If we just look with your
ophthalmoscope at your retina
when you get your eye exam,
what is the optometrist seeing?
This is the retina from
looking into the eye.
And we'll see in the
center of the retina
an area called the
fovea centralis.
Fovea centralis.
The fovea centralis
has only cones,
so it will have the
most acute vision.
This is where you're
focusing the light back
into a specific area.
So most acute vision is
in the fovea centralis.
And surrounding the fovea
centralis what do we have?
An area called-- hm.
It's yellow on the outside
and white on the in.
It looks like we have
no more yellow chalk.
This one looks yellow inside.
In yellow then, we've
put in the macula lutea--
macula lutea-- which
means yellow spot.
Macula is spot.
Lutea is yellow.
So it surrounds,
so you know where
your fovea centralis is because
of the presence of the macula
lutea.
But what I'm leading
up to is where
is the blind spot in
relationship to the fovea
centralis?
And so, if this is my nasal side
and this is my temporal side--
you can picture
this on yourself--
we'll find the blind
spot about here.
It's on the nasal side.
It equals your optic
disc or blind spot.
Have you ever tested yours
to be sure you have one?
Anybody not tested it?
You tested yours?
Put your finger in
front of your eye,
in front of your right eye,
and then look straight forward,
and then move your
finger to the right
and see where your
finger disappears.
Do you see where it disappears?
No, you're not looking--
you're following your finger.
That's not--
[LAUGHTER]
Look straight ahead.
Look straight ahead at
your red shirt back there,
and I'll move my finger, and
it disappears right about here.
I don't see the finger.
It's crossing your blind spot.
Can you get it?
Some can and some can't.
Try it on your own.
And why do we teach this?
How often have you pulled
out from a stop sign,
you've looked once and you don't
see any cars so you pull out
and all of a sudden, where
did that car come from?
That car was in your blind spot.
So I always say, when you
pull out from a stop sign,
turn your head twice
so you can catch it.
But you'll find it's really very
important for a safety factor.
All right, so we've got a brief
introduction to our retina.
And let me be sure I've got
all I want to give here.
So let's just follow
our optic nerve back
so you get the general
idea of how its
organized going to the brain.
[CHUCKLES]
Somebody's sleepy.
All right, let's take this.
We can have lots of
these coming back.
All right, what have we done?
Well, we have our
temporal field of vision
out here, our nasal
field, our nasal field,
our temporal field.
Field of vision.
And we formed here, what?
The optic nerve.
So if we cut the
optic nerve, what
are we going to see clinically?
I've only cut it here.
This is my right eye.
This is my left eye.
What are you going to see?
STUDENT: [INAUDIBLE]
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: Sure,
it's very simple.
You've cut all the pathway
that's coming from the eye.
So if I cut it, you get
right eye blindness.
Isn't that simple?
Nothing complex there.
Let's put a pituitary tumor in.
You've seen where
the pituitary is.
You know it's in the
sella turcica, right?
Part of your, which bone?
Pardon?
I hear mumbles, but which bone?
STUDENTS: Sphenoid.
MARIAN DIAMOND: Sphenoid, sure.
Terribly important.
You forgot all that already?
My, we'll have to put some of
those questions in the exam
and get you reviewing.
So here we've got a pituitary.
And the pituitary has a tumor.
So with a tumor,
what are we going
to see in our visual field?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: We're
catching information coming in
from the temporal field.
Right?
So these fibers are cut off.
So you'll have, in your
eye, no temporal vision.
You'll have blindness
out here in the field.
So it's a bitemporal--
We'll just call it blindness,
but it's called hemianopsia.
But I won't give you the word.
We'll just put blindness
to make it easier for you.
But to figure out, when you
damage the visual system,
you have to know
what the pattern is
so you can see the problems.
This then is my optic nerve.
Where it's crossing here,
this is the optic chiasm.
Optic chiasm.
This is the optic tract.
You get different
problems with vision,
in peripheral vision
or external vision,
if you have damage in
various parts of the pathway.
So this is my optic tract.
And what's important, just
so you've heard of it,
is this loop here.
These fibers, this area
is my thalamus here,
where they're having a
synapse in the thalamus.
All sensory pathways
synapse in the thalamus.
We have the same
nerve all the way
from the retina all the
way back to the thalamus.
And then we get new fibers
coming to the visual cortex.
But why do I mention this?
Because this loop,
called Meyer's loop,
is very important
anatomically to know
that some of these visual
fibers are going forward here
instead of backward.
Why is that important?
When the surgeon does
a temporal lobectomy--
a person has incurable
epilepsy and they
want to get rid of the source
and it's in the temporal lobe--
they remove the temporal lobe.
But if they're not careful--
See, the temporal lobe's
out here like this,
and they'll cut it off, and
they'll cut that Meyer's loop.
So why it's important to
know the so-called deviance
from what you'd anticipate.
It's obviously a
developmental thing.
When the brain was growing, it
carried these fibers forward
and then determined
to come on back again.
But that's Meyers loop.
And then, back to
your visual cortex.
What number did we give to
your primary visual cortex?
It's V1, right, but--
STUDENT: Area 17.
MARIAN DIAMOND: Pardon?
STUDENT: It's area 17.
MARIAN DIAMOND: Area 17, sure.
This is area 17.
So many people work
on the visual cortex
that I want you to at least be
aware of what they call it--
RV1.
So do you appreciate
everything you see now,
what it has to go through?
And this is just
minuscule compared
to what really goes on.
So now, let's see if we've
given you the basics here.
Let's look at the
coats of the eye,
because we've got to
protect this retina.
So the coats, we're
going to have three.
One will be the retina,
two will be the uvea,
and three will be the
sclera and the cornea.
So we've done the retina.
Let's get our eyeball.
We need a big area to work.
So this is our optic nerve.
This is our retina.
And so we can start
putting on our coats.
Let's put on the uvea.
It consists of three parts--
the choroid, the ciliary body--
whoops, I don't want to
get too close there--
and processes, and the iris.
So we're going to put in
our choroid coming around
outside our retina.
So this will be choroid.
And the choroid is
primarily vascular.
Vascular.
And then it expands
into this ciliary body.
Choroid was number one.
This is number two.
And it has processes, little
finger-like projections.
And what are those little
finger-like projections
holding?
What do we need here?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: Pardon?
STUDENT: A lens?
MARIAN DIAMOND: A lens, sure.
So they're going to
be holding the lens.
What's a lens made of?
Have you ever dissected an eye?
Have you ever taken the lens
out and put it on a newspaper?
And what happens to
the newspaper print?
It magnifies.
When you go out
into the classroom
the kids love it because a lens
is made of epithelial cells,
and yet they can magnify.
Hold it in your hand and
they change their chemistry.
So we haven't had that
before in the body.
We'll come back if we
have time because we
want to finish our coats.
So the other structure that
we need will be the iris,
and the iris is going
to come around here.
So this is as we see the
iris, in this position.
If we take the iris and
look at it from in front,
we'll see just the
disc with the pupil.
And here would be
your pupil here.
And we'll have the
muscles that we've
mentioned before in the iris.
We have those that are circular.
What were they
doing to the pupil?
These are circular muscles.
What are they going
to do to the pupil?
STUDENTS: Constrict.
MARIAN DIAMOND:
Constrict, right.
Constrict pupil.
And then we have the radial
muscles going from inside, out.
These are radial muscles.
What's going to happen
when they constrict?
STUDENTS: Dilate.
MARIAN DIAMOND: Dilate, sure.
You can just see that
these are muscles.
When they do this,
the pupil enlarge.
So dilate.
So you don't just
have to memorize,
you can figure them out.
It's so nice when students come
to the lab, the office hours,
and they're beginning to
work with the information
and they can figure things out.
It's just beautiful to see.
Dilate pupil.
All right.
We have one more coat to go.
We have the sclera.
So sclera will be
made of dense, they're
white gelatinous fibers.
So what's the common
name for this layer?
When you look at
somebody and they've
been studying all night.
Your sclera's
supposed to be white
and it's red because
you've worked so hard.
So the sclera, the
white of the eyes,
will be connective tissue.
Protecting.
It's like the dura
around the CNS and PNS.
So this is our sclera.
And anteriorly, it's going
to become translucent.
And what's it going to form?
The cornea.
Again, the cornea is made
of collagenous fibers
but they've changed
their chemistry
so that light can get through.
These are collagenous fibers,
but they're translucent.
Anybody had a corneal transplant
or know of anybody who can?
Wonderful things they
can do today, right?
Now, at the junction, between
the cornea and the sclera--
junction of cornea and sclera--
two more things I'd like to
say and then we'll show slides.
Junction of cornea
and sclera are
what are called the
canals of Schlemm.
Another one of these
scientists with a great name.
Canals of Schlemm.
There is fluid, posterior,
in the chambers.
In here it's being formed
and it has to get back
into the venous system.
So it gets back into
the venous system
through the canals of Schlemm.
So fluid posterior to cornea.
Does anybody know what
to call that fluid?
Aqueous humor.
It goes into canals of Schlemm,
back into the venous system.
So what happens if those
canals of Schlemm are blocked?
STUDENT: You block the flow.
MARIAN DIAMOND:
You block the flow.
You increase the pressure.
What did we call the condition?
Glaucoma.
You've heard of glaucoma.
It's when canals of
Schlemm are blocked.
So if we block canals of
Schlemm, you get glaucoma.
So you can go in with
a laser, open them up,
and get some drainage.
Get rid of it.
What do we do when
you get a cloudy lens?
What do we call a cloudy lens?
STUDENT: Cataract.
MARIAN DIAMOND: Cataract.
What do you do when
you get those today?
You get a lens transplant.
And the best place
in the world for you
to get a lens transplant is
this Turner down in San Leandro.
The head of neurosurgery
at UCSF once
said, the best
gift he could give
me was to tell me the name
of Tom Turner in San Leandro.
And everybody I've known
I've said, "Go down to him
to get your cataracts removed
and get your lens replaced."
And they don't have problems.
Other places, they're
still having problems.
Since he gave it to me, I
figured I'd give it to you.
We've got a few slides.
Let's go through.
All right.
I just wanted you to see
the histology of the cortex
to know that this is
filled with pyramidal cells
and stellate cells.
But layer one of the cortex
has no pyramidal cells
or no stellate cells.
So you always know
where layer two
begins because one has no
pyramidal-- it has other cells,
but not pyramidal or stellates.
Next one.
And this is one of your
pyramidal cells I've shown you.
The reason it's so
blurry is because it's
cut thick so that we can
get the branches in here.
It's cut at 150 mU and we
normally work at 10 mU or 6 mU.
Here's the big apical dendrite.
You don't get many other
dendrites coming off.
And the axon's so thin
you don't see them.
But we know these are
not axons, any of them,
because they have
dendritic spines.
Next one.
This is a stellate cell.
Stellate cell.
It's got its processes.
One looks a little
bit thicker here.
But on the whole, it doesn't
have a pyramidal shaped body.
The next one.
And these are just
the eye muscles.
What fill your
orbit then will be,
obviously, your eyeball,
your eye muscles.
But in addition,
it's packed with fat
to cushion the eyeball.
The next one.
And this gives you the basics.
You could see the
artery that's coming
into the retina is from
what major artery coming
into the skull?
STUDENT: [INAUDIBLE]
MARIAN DIAMOND: No.
The internal carotid.
Do you remember the first
branch of your internal carotid
was the ophthalmic artery.
When you look at an eyeball
through an ophthalmoscope,
you'll see the artery.
It's come up through the
optic nerve all over.
It's just wonderful to look at
somebody's ophthalmic arteries
so clearly.
But then you can see that
we'd have the retina and then
the pigmented
epithelium showing here.
There are different names
that I didn't give you.
But you come up
into where you'll
have the ciliary body,
the ciliary processes,
and ligaments that
suspend the lens.
And it's the
contraction of muscles
in the ciliary body which
allow the lens to change shape.
Next time I'll tell
you how that works.
But here's the iris here.
Here's the pupil between
the two ends of the iris.
And this is this
anterior chamber
that's filled with the liquid.
And the canals of
Schlemm are here,
at the junction between
the sclera and the cornea.
Right there.
There are other parts.
We'll have to give a
little bit more on Monday.
Next one.
And this gives you a picture
of the retina with the rods
and cones and a horizontal
cell for lateral excitation.
And then the bipolar
cells which are
synapsing with
the rods and cones
and with the ganglion cells.
And here are the
amacrine cells, which
are again lateral distribution.
And then your
ganglion cells connect
with the lateral inhibition
cells and the bipolar cells.
And here are your
ganglion cells,
whose axons will make
up the optic nerve.
The next one.
And this shows the optic
nerve, the optic chiasm.
Here's the pituitary.
So you could see, pituitary
tumors can encroach.
When they remove a pituitary,
they keep you awake
so you can tell whether they're
touching your optic chiasm
to see whether you get
any diminution of vision
while they're trying
to take out the tumor.
Optic tract coming back
to the lateral geniculate
of the thalamus.
And then it will loop around
and come back to your cortex.
It's a beautiful dissection.
These are your olfactory
tracts and olfactory bulbs,
very nicely here.
Next one.
That's it.
Enjoy your holiday.
