If we unfold your brain, okay?
Which is generally painful, all right?
What we have to do is we have to sort of take all this crinkled stuff and
then open it up and layer it.
What you would see is something that looks like this.
And bare with me here, okay?
What's happened here is, this here is your eyeball, right there.
This back area is V1, they're showing,
this is on the inside, this is on the outside.
Here's your nose here.
This is the, these are your visual cortex areas here.
And, if I were to peel it out, so take this brain and flatten it out, okay?
You would get a map that looks something like this, so this big area here is V1,
that's this area back in here.
It wraps around.
Then there's these other visual areas.
Anything starting with a v is a visual area.
And then it goes all the way up and
here's that, so this is wrapping around this whole body, right?
Here's that somatic sensory, the feeling.
Here's your motor cortex, whole bunch of these other areas.
Okay, this is what you would see.
All right, but of course this is just a drawing.
Now I want to show you a picture that's kind of cool and
kind of gross at the same time, all right?
And here's what we're going to do, and again, PETA folks, turn this off.
All right.
You take an animal, a living animal, you immobilize its eye by giving
an injection that prevents the eye muscles from moving the eye, okay?
You put up a flashing pattern that's in like some rings,
that alternate sort of bright and dark spots, and you turn that on, but
remember the eye can't move, so the eye is fixed at the same point.
You then inject essentially a type of radioactive substance into
the bloodstream that binds with sort of the oxygenated red blood cells.
And the more cells work, the more oxygen they consume, okay?
So, you can measure, so this is like,
one of the first ways of measuring the activity of the blood cell, of, of the,
of the brain cells by, you have them do this work for a while,
while this radioactive tracer's connected to red blood cells and oxygen.
And what happens is the blood cells that are doing a lot of work,
build up a lot of this radioactive material.
But of course, you have to get a picture of that radioactive material, and
it's a very thin little bit of material, in a very thin part of the brain.
So what you have to do is what they refer to as euthanize the animal.
So the animal is, is, killed.
You then, very carefully, un-peel its brain.
And you can take a radiograph, you can actually measure, you know, you,
you can think of it as simply as putting the brain, that brain tissue
next to a photographic plate, and the radioactivity makes an image, okay?
There's a little more to it than that.
When you do that, you get this remarkable picture, and
this one comes from 1988.
So, even though this is sort of very fundamental work,
it's not all that old, okay?
And here is what the animal was looking at, okay?
It's macaque.
All right, so here you can see the, the visual stimulus the animal's looking at.
And here is the, the picture of its brain.
And what's so cool is that this structure is preserved.
This is what's referred to as retinotopic mapping,
is preserved within the cortex, okay?
So, when you move a little bit in the retina, you move a bit in the cortex.
Now what's also really cool is that it is not one-to-one,
in terms of, how much cortical area is devoted to how much of the retina?
In fact, the way it's drawn
out is sometimes referred to as log polar, et cetera.
And again, this is where we've unfolded your, your visual field.
And you see that like this little area, 1 2 3 4,
is looking at a lot on the visual cortex.
And this area out here, okay, is much, much smaller.
So you use more brain real estate for that tiny little area in the middle
of your visual field, than you use real estate for bigger areas out here.
Which also, I mean, yes,
it makes sense, because that's where all the processing needs to be.
But the fact that you can actually find this in the actual tissue is, you know,
in some sense remarkable.