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PROFESSOR JOHN GABRIELI: Last
time we discussed how people

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can approach psychological
issues in terms of

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experiments, and at least
correlations in some cases or

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causal studies through
experiments.

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And we discovered that
if you think

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about money, what happens?

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On average, you become more
self-reliant or less willing

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to help, right?

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We discovered that if you just
change the way that men and

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women approach each other at a
dating event, you change their

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internal feelings and their
external behaviors simply by

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who's approaching whom.

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So we learned all kinds of
things that you might or might

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not have known unless you
did the experiments.

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And for all these things that
are our mental life-- our

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thoughts, our feelings,
they are all

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supported by our brains.

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And so for me personally as a
neuroscientist, I've always

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thought that the brain is one
of the three amazing things

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out there in the
natural world.

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With the origins of the
universe, the origin of life.

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And the brain that allow us to
think and feel, to see, that

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remember, really everything that
we do comes from that.

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OK.

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So here's this device.

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And I want to share with you
just this phrase that people

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sometimes use, which is
that your mind is

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what your brain does.

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That your mind is what your
brain does And so the readings

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from Oliver Sacks for today kind
of remind you of that.

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So there are two women who have

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seizures of various kinds.

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And what happens in them?

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So one is Mrs. OC, 88-year-old
woman.

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And what starts to
happen to her?

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She starts to hear songs.

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And so powerfully, not just when
you have a little song in

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your head, that it's hard for
her to hear conversations.

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For her, a conversation like
we're having now, it's as if

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the music stayed
on really loud.

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Turns out she's having temporal
lobe seizures.

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The temporal lobes are the parts
of the brain that are

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terribly important
for hearing.

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So music is something
that we hear.

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And then she has a right
temporal lobe infarction.

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She's had an injury in the
right temporal lobe.

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Music, for most of us, is more
dependent on right hemisphere

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processes than the left.

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So that makes it unusual.

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And how does she feel about
the whole process?

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So what's generating
the songs, though?

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What's generating the songs
that she hears?

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Yeah, her memory.

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Her brain, right?

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Because in epilepsy,
what's happening?

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Neurons are firing.

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When neurons fire in organized
patterns, those are memories,

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desires, physical actions,
thoughts.

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When they're firing for no good
reason like an epilepsy

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because of some brain
difficulty,

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they just start firing.

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But the neurons that happen to
be firing will drive certain

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mental processes that they
normally support.

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In this case, the neurons that
are firing away are ones that

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are involved in memory
or songs and

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perception for songs.

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And when they fire, it's as if
you heard the song itself.

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Because when you hear my voice
or when you hear a song,

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you're never hearing the song.

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You're always hearing what your
neurons are interpreting

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the sound that comes
to your ear.

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Your mind is what your brain
does in that sense, and in a

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very central way.

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If you had an injury in that
part of the brain, you can be

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cortically deaf and never hear
a sound, even though all the

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information came through
your ear.

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So without your brain
interpreting the environment,

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you wouldn't know what it is.

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But if your brain starts to fire
on its own, that's just

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as good a signal as if you
heard a song itself.

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Because that is the stuff
of hearing songs.

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So she enjoyed it, actually.

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She declined taking
anti-convulsive medications.

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Because she felt it was a portal
to her past, right?

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The songs that she heard were
ones that reminded her of her

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life and were kind of
pleasant to hear.

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It was like being on a nonstop
highlight film of for life, or

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a highlight MP3.

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So now an opposite response to
a similar phenomenon comes

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from a Mrs. OM in her 80s.

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She hears songs, but she
also hears a lot

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of ringing and hissing.

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It's not limited to
the song itself.

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She doesn't mention any
of this for how long?

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Four years.

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She's hearing ringing,
hissing, songs.

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She knows because her mind is
fine that they're coming from

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nowhere but inside her head.

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But she doesn't tell anybody.

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That's a huge burden, right?

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And why doesn't she tell them?

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Yeah, yeah.

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And especially if you're in
your 80s, and you're going

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around saying, I'm hearing
things, people go, OK.

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Were putting you in the
old age home, right?

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You're out of it.

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So she doesn't want to
give up her freedom.

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And she gets a short playlist,
just three songs, and hears

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them over and over
and over again.

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You may have had the experience
that some songs you

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hear for a while.

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You like them more, and then
you get tired of them.

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If you had only three all the
time, every day, and a bad

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version that was hissing and
ringing, you would get pretty

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tired of the songs too.

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That stops by anti-convulsive
medications and medications

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that stops the seizures,
stop the songs.

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And so it's sort of a beautiful
story, when two

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opposite emotional responses for
how your mind is what your

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brain does.

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Now from this, the fact that
songs are played back as if

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you had pulled out songs from
your computer or shelf

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somewhere, you might think that
the brain retains these

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records perfectly throughout
life and epilepsy

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would just sort them.

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But we'll come back to that
later on, and say that in very

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much, we don't think
memory is that way.

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But we do remember songs that
are important for us.

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And if our brain just starts
firing in the same place where

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we store those songs, we hear
them just as real as your

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cortex hears it when it hears
the actual song itself.

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Because that's the place
where you hear it.

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So this is the kind of evidence
that at least in some

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sense, your mind is what
your brain does.

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And so here's this
amazing brain.

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It's about two to
three pounds.

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But every thought and feeling
you'll ever have, or every

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physical movement, every desire,
every thing that

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you're proud of or ashamed of
that crosses your mind will be

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supported by this structure.

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So I'm going to talk a little
bit about the neurons, just a

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little bit about the neurons
that compose the brain, and a

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little bit about a quick tour
through the gross organization

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of the brain.

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We'll come back to many of these
structures as they're

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relevant to different things
like memory or emotion or

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personality later
in the course.

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Talk a little bit about the
enterprise of trying to say

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which parts of our brain
support which

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parts of our mind.

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Missteps about that, famous
cases about that, that have

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turned out to have roughly
the right message.

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And we'll focus on hemispheric
specialization, the thing in

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humans where our left hemisphere
and our right

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hemisphere are organized to
accomplish different things,

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to support different
mental functions.

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And the surprise from split
brain or commissurotomy

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patients, that these different
mental lives that support our

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different parts of
the brain, that

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they can live in isolation.

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They don't even know they're
there one to the other.

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So let me rephrase this.

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As you sit there, the thought is
you might have independent

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parts of your mind supported
by independent

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part of your brain.

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And at any one moment, your
consciousness might be in one

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part, and then it might
move to another.

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And just like there's all these
people in this room,

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your brain might be all these
things having their own

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independent thinking lives.

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They have to interact a lot.

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But how much might there be
independent modules in your

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brain that are doing
their own thing.

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And now you're thinking about
music, and those turn on, and

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that's where your consciousness
is.

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Now you're thinking
about history.

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Now you're thinking about
dinner tonight.

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And different parts of your
brain turn on and that's when

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your consciousness is moving
from one part of your

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brain to the other.

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But the other parts
keep going.

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So we'll see how plausible
is that.

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So it took a long time for
people to decide that the

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brain actually is the
stuff of the mind.

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Smart philosophers like Plato
said, well, it's part of the

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body that's closest
to the heavens.

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That's where the gods might
reside, so that's a good place

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to have your mind and that's
where your brain is.

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A sort of GPS approach
to locating where

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the mind might be.

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Aristotle said, wait a minute.

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It's the warm and active heart--
the heart was very

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impressive in post-mortem
examination of people who have

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passed away--

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that houses the mind.

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And that it cools, and there's
an inner brain.

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So the brain was kind of a
radiator that would sort of

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cool stuff off to keep
the heart in optimal.

00:09:07.630 --> 00:09:09.110
And even now, we talk
about people having

00:09:09.110 --> 00:09:10.580
a big heart, right?

00:09:10.580 --> 00:09:12.250
A cold heart, a warm heart.

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We still talk about human
personality or character in

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terms of heart.

00:09:17.700 --> 00:09:20.230
Galen said that the brain
was surrounded-- there's

00:09:20.230 --> 00:09:22.070
ventricles in the middle of
the brain that have fluid,

00:09:22.070 --> 00:09:23.400
cerebral spinal fluid.

00:09:23.400 --> 00:09:27.000
And he hypothesized that the
brain was the packing material

00:09:27.000 --> 00:09:28.580
that protects that fluid.

00:09:28.580 --> 00:09:30.560
Hang on to that fluid, that's
all your stuff.

00:09:30.560 --> 00:09:32.410
We're going to cram a lot of
stuff around it, right?

00:09:32.410 --> 00:09:34.890
Like the bubble pack that
comes in the boxes.

00:09:34.890 --> 00:09:36.720
And of course now we know it's
the opposite way around.

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The mind is in the physical,
the dense part of

00:09:39.370 --> 00:09:40.420
the brain, not that.

00:09:40.420 --> 00:09:43.270
And then ideas from Descartes,
the pineal body is one of the

00:09:43.270 --> 00:09:46.660
very few structures that's in
the midline of the brain, that

00:09:46.660 --> 00:09:49.210
doesn't have a thing on the left
and a thing on the right.

00:09:49.210 --> 00:09:52.560
And so he thought maybe that's
where things get unified in

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the whole brain.

00:09:53.180 --> 00:09:55.290
It all comes together
as the place that

00:09:55.290 --> 00:09:56.390
runs the whole brain.

00:09:56.390 --> 00:09:57.290
And that's a wrong idea.

00:09:57.290 --> 00:10:00.530
But people were trying to figure
out what was going on.

00:10:00.530 --> 00:10:03.670
In modern neuroscience,
there's many levels of

00:10:03.670 --> 00:10:05.300
analysis of the brain.

00:10:05.300 --> 00:10:08.480
So if you go to any neuroscience
program, like

00:10:08.480 --> 00:10:09.880
Department of Brain and
Cognitive Science, you will

00:10:09.880 --> 00:10:12.440
actually see scientists who
study things like molecules

00:10:12.440 --> 00:10:15.830
and synapses, molecular
neurobiology, how neurons

00:10:15.830 --> 00:10:18.870
work, how neurons form networks,
little organizations

00:10:18.870 --> 00:10:22.270
of things that solve problems
at a higher level, maps,

00:10:22.270 --> 00:10:24.330
systems in the brain
as a whole.

00:10:24.330 --> 00:10:27.060
In this course, we mostly have
to operate at this level.

00:10:27.060 --> 00:10:29.590
That's the place where it's easy
for us to relate in some

00:10:29.590 --> 00:10:32.700
ways parts of the mind as we
understand it, of human nature

00:10:32.700 --> 00:10:34.720
as we understand it, and
physical parts of the brain.

00:10:34.720 --> 00:10:36.400
It's very hard for
us to get that to

00:10:36.400 --> 00:10:37.920
molecules at the moment.

00:10:37.920 --> 00:10:40.910
But lots of neuroscience is
working to connect these

00:10:40.910 --> 00:10:41.940
things at different levels.

00:10:41.940 --> 00:10:44.970
And I can't resist talking for
one second, too, about the

00:10:44.970 --> 00:10:46.730
fact that we know our
brains were not

00:10:46.730 --> 00:10:48.760
designed from scratch.

00:10:48.760 --> 00:10:52.680
You are not humans 3.0
or 98.0, right?

00:10:52.680 --> 00:10:56.180
Everything in us in some way
evolved from other species

00:10:56.180 --> 00:10:58.270
that were similar to us,
and far enough back,

00:10:58.270 --> 00:10:59.440
dissimilar to us.

00:10:59.440 --> 00:11:02.450
So there's lots of speculation
about how it is that we

00:11:02.450 --> 00:11:05.360
balance parts of the brain
that are ancient in their

00:11:05.360 --> 00:11:07.540
evolutionary roots, that are
more recent in their

00:11:07.540 --> 00:11:09.830
evolutionary basis, and what
that means about us.

00:11:09.830 --> 00:11:13.520
Another sense in which we're
comprised of multiple society

00:11:13.520 --> 00:11:16.940
of brain systems in
between our ears.

00:11:16.940 --> 00:11:21.110
So we know the cells in the
brain are glia support cells

00:11:21.110 --> 00:11:22.760
and neurons, that a neuron--

00:11:22.760 --> 00:11:23.900
and I know you all
know all this.

00:11:23.900 --> 00:11:25.990
Oh, let me say a word
about notes.

00:11:25.990 --> 00:11:30.610
So we sent PDFs of the lecture
notes from the first two

00:11:30.610 --> 00:11:32.370
lectures and the third
one just recently.

00:11:32.370 --> 00:11:35.930
Starting tomorrow, we'll send
you the PDF of each lecture,

00:11:35.930 --> 00:11:37.890
the latest by the night
before the lecture.

00:11:37.890 --> 00:11:40.820
So you will be able to
print it out or look

00:11:40.820 --> 00:11:42.230
at it on the computer.

00:11:42.230 --> 00:11:44.990
But neurons have a soma
or cell body.

00:11:44.990 --> 00:11:47.930
Those make up the grey matter
when we look at the brain.

00:11:47.930 --> 00:11:50.570
They have an axon that can be
covered with myelin that makes

00:11:50.570 --> 00:11:52.330
the white matter.

00:11:52.330 --> 00:11:55.540
The dendrite is the extensions
of the neurons that have the

00:11:55.540 --> 00:11:57.700
input to the neuron.

00:11:57.700 --> 00:11:59.300
We know that neurons
communicate by

00:11:59.300 --> 00:12:03.660
neurotransmitters across
synapses, junctions between

00:12:03.660 --> 00:12:06.140
different parts of neurons.

00:12:06.140 --> 00:12:07.610
When you have a collection
of cell bodies,

00:12:07.610 --> 00:12:09.110
people call it a nucleus.

00:12:09.110 --> 00:12:11.490
When you have a collection of
axons, they call it a tract.

00:12:11.490 --> 00:12:12.860
It's just vocabulary
and stuff.

00:12:12.860 --> 00:12:15.360
And you know this from other
courses, just reminding you

00:12:15.360 --> 00:12:16.190
about them.

00:12:16.190 --> 00:12:18.650
And then you get these
unbelievably startling kinds

00:12:18.650 --> 00:12:21.090
of numbers, which are always
huge estimates.

00:12:21.090 --> 00:12:25.180
But they show you how amazing
your brain is, and how hard it

00:12:25.180 --> 00:12:30.560
is for us to deeply understand
how the brain works.

00:12:30.560 --> 00:12:33.150
I mean, we understand incredibly
more than we did 10

00:12:33.150 --> 00:12:35.440
years ago, 20 years
ago, 30 years ago.

00:12:35.440 --> 00:12:37.950
We're incredibly far from
understanding how your brain

00:12:37.950 --> 00:12:40.950
accomplishes the amazing
things it accomplishes.

00:12:40.950 --> 00:12:43.360
So it has about 100
billion neurons.

00:12:43.360 --> 00:12:46.810
It has about 100 trillion
synapses, connections among

00:12:46.810 --> 00:12:48.500
neurons and dendrites.

00:12:48.500 --> 00:12:52.410
If you were to lay out the very
thin myelinated axons in

00:12:52.410 --> 00:12:55.870
your brain, just the big axons
that get myelin, it's

00:12:55.870 --> 00:13:00.090
estimated that you'd have
62,000 miles of axons.

00:13:00.090 --> 00:13:01.020
That's pretty good, right?

00:13:01.020 --> 00:13:04.270
Now you really want to wear
helmets when you go

00:13:04.270 --> 00:13:05.740
skateboarding or anything,
right?

00:13:05.740 --> 00:13:09.370
And about 100,000 miles of
dendrites in each of you.

00:13:09.370 --> 00:13:11.650
So this is why the brain
is amazing and hard.

00:13:11.650 --> 00:13:15.080
It's fantastic in
its complexity.

00:13:15.080 --> 00:13:19.200
An average neuron may have up
to 15,000 connections, 1,000

00:13:19.200 --> 00:13:24.430
synapses, and up to
1,000 neurons.

00:13:24.430 --> 00:13:25.680
There's different ways
of thinking about the

00:13:25.680 --> 00:13:27.160
computational power
of a neuron.

00:13:27.160 --> 00:13:30.780
But they estimate that these
might have, each one the

00:13:30.780 --> 00:13:33.200
computational power of
something like a

00:13:33.200 --> 00:13:34.310
medium-sized computer.

00:13:34.310 --> 00:13:38.460
So it's not the best computer,
but you've got

00:13:38.460 --> 00:13:40.760
100 billion of them.

00:13:40.760 --> 00:13:42.780
Now, that's the easy part.

00:13:42.780 --> 00:13:45.190
Take 100 billion neurons and
your computer's in your head.

00:13:45.190 --> 00:13:47.040
The hard part is to get them
all working together

00:13:47.040 --> 00:13:47.660
efficiently.

00:13:47.660 --> 00:13:51.030
And you're not sitting around
going, "Computer 33, get up to

00:13:51.030 --> 00:13:52.720
speed here.

00:13:52.720 --> 00:13:54.620
Something's wrong here." You
don't even think about them.

00:13:54.620 --> 00:13:56.110
You just go about
your business.

00:13:56.110 --> 00:13:58.400
The time for information to go
from neuron to neuron is

00:13:58.400 --> 00:14:01.250
pretty slow compared to fast
computers, pretty fast for

00:14:01.250 --> 00:14:02.800
biology, 10 milliseconds.

00:14:02.800 --> 00:14:05.100
And everybody thinks the secret
of the brain, whatever

00:14:05.100 --> 00:14:07.960
it will turn out to be in many
ways, is that you can run a

00:14:07.960 --> 00:14:11.330
fantastic number of computations
simultaneously

00:14:11.330 --> 00:14:12.930
and collaboratively.

00:14:12.930 --> 00:14:14.640
But we don't have a deep
understanding of how

00:14:14.640 --> 00:14:15.715
that all plays out.

00:14:15.715 --> 00:14:20.000
So here's a cartoon of this
amazing axon, the cell body,

00:14:20.000 --> 00:14:21.600
and the dendrites to
get inputs to it.

00:14:21.600 --> 00:14:24.865
The axon is the output signal
of a typical neuron.

00:14:24.865 --> 00:14:27.770
Neurons can have these beautiful
arborizations,

00:14:27.770 --> 00:14:30.500
tree-like properties
of dendrites.

00:14:30.500 --> 00:14:32.850
Neurons have all kinds of
different shapes in different

00:14:32.850 --> 00:14:35.070
parts of the brain, presumably
reflecting their different

00:14:35.070 --> 00:14:38.416
missions, what they have
to accomplish.

00:14:38.416 --> 00:14:42.400
An incredibly complicated
cellular factory inside all of

00:14:42.400 --> 00:14:44.980
them is producing different
things.

00:14:44.980 --> 00:14:46.600
This is a big overview.

00:14:46.600 --> 00:14:48.850
This is not for you to learn
a specific fact.

00:14:48.850 --> 00:14:51.000
And this, here's an actual
neuron that's injected in the

00:14:51.000 --> 00:14:54.780
fantastic tree of connections it
makes within the neurons to

00:14:54.780 --> 00:14:56.930
accomplish its mission.

00:14:56.930 --> 00:14:59.670
Here's a cartoon of a synapse,
places where neurotransmitters

00:14:59.670 --> 00:15:03.750
signal from one axon to one
dendrite, for example.

00:15:03.750 --> 00:15:05.370
Here's an actual picture.

00:15:05.370 --> 00:15:09.010
Here's the package of vesicles
that house the

00:15:09.010 --> 00:15:11.230
neurotransmitters in them,
making a connection or a

00:15:11.230 --> 00:15:13.390
synapse onto a dendrite.

00:15:13.390 --> 00:15:15.420
And you just have a fantastic
number of these.

00:15:15.420 --> 00:15:18.140
And as you're sitting in you
right now an unbelievable

00:15:18.140 --> 00:15:21.090
amount of stuff is going on--
releasing them, cleaning them

00:15:21.090 --> 00:15:23.720
away so they don't hang around
too long, building new ones to

00:15:23.720 --> 00:15:24.640
get ready to go.

00:15:24.640 --> 00:15:28.780
It's just an unbelievable story
per neuron, never mind

00:15:28.780 --> 00:15:30.050
the whole of them.

00:15:30.050 --> 00:15:32.430
So now we take a step back
to the brain as a whole.

00:15:32.430 --> 00:15:34.050
Here's the front of the
brain, top of the

00:15:34.050 --> 00:15:35.210
brain, back of the brain.

00:15:35.210 --> 00:15:37.210
I'm going to say a word about
the cerebellum, which we'll

00:15:37.210 --> 00:15:39.840
talk very little about
in this course.

00:15:39.840 --> 00:15:42.120
The cellular organization
of the cerebellum is so

00:15:42.120 --> 00:15:45.190
consistent that people estimate
that half of all the

00:15:45.190 --> 00:15:47.460
cortical neurons in the brain
are in the cerebellum.

00:15:47.460 --> 00:15:50.480
And if you see this cerebellar
size is small, not that large,

00:15:50.480 --> 00:15:52.990
it's because it's packed
so tightly.

00:15:52.990 --> 00:15:55.250
And it's so consistent in its
organization that people

00:15:55.250 --> 00:15:57.830
thought, that's the first part
of the brain we'll crack.

00:15:57.830 --> 00:16:01.110
Because the organization is so
clear that we'll be able to

00:16:01.110 --> 00:16:03.060
figure out what it's computing
and how it does it.

00:16:03.060 --> 00:16:05.450
And it's turned out to be
about as mysterious a

00:16:05.450 --> 00:16:07.030
structure as any.

00:16:07.030 --> 00:16:08.730
I can't tell you the number of
debates about what people-- we

00:16:08.730 --> 00:16:11.140
know it's involved in motor
control, but in many other

00:16:11.140 --> 00:16:12.760
things, as well.

00:16:12.760 --> 00:16:16.080
The wiring diagram, knowing it,
what's connected to who,

00:16:16.080 --> 00:16:19.270
turns out to be only a tiny step
in understanding how what

00:16:19.270 --> 00:16:21.610
part of the brain does
what it does.

00:16:21.610 --> 00:16:24.800
So here's this mysterious
cerebellum.

00:16:24.800 --> 00:16:28.550
And then here's a basal ganglia
that we know is

00:16:28.550 --> 00:16:30.280
involved in movement.

00:16:30.280 --> 00:16:31.620
Parkinson's Disease
affects it.

00:16:31.620 --> 00:16:33.530
Huntington's Disease
affects it.

00:16:33.530 --> 00:16:37.410
It's also involved in learning
habits of all kinds.

00:16:37.410 --> 00:16:40.240
It's also involved in the reward
systems of the brain.

00:16:40.240 --> 00:16:42.420
What have we found delightful
and important?

00:16:42.420 --> 00:16:45.290
What did we want to do
because the reward

00:16:45.290 --> 00:16:47.240
system is turned on?

00:16:47.240 --> 00:16:49.110
We'll come back to
that later on.

00:16:49.110 --> 00:16:51.210
And then the limbic system, the
part of the brain that's

00:16:51.210 --> 00:16:54.060
involved in emotion
and memory--

00:16:54.060 --> 00:16:55.200
amygdala and hippocampus.

00:16:55.200 --> 00:16:55.950
We'll come back to that.

00:16:55.950 --> 00:16:58.440
If you don't have this structure
intact, you can't

00:16:58.440 --> 00:17:00.340
form new memories ever again.

00:17:00.340 --> 00:17:04.190
We'll talk about patients
like that.

00:17:04.190 --> 00:17:06.010
And then we'll come to the
smarts of the brain, the

00:17:06.010 --> 00:17:08.520
cerebral cortex, four lobes--

00:17:08.520 --> 00:17:11.839
frontal, parietal, occipital,
and temporal.

00:17:11.839 --> 00:17:16.550
You have four on the left
and four on the right.

00:17:16.550 --> 00:17:18.540
These lobes are comprised
of gyri.

00:17:18.540 --> 00:17:20.369
That's the part of the brain
that sticks out.

00:17:20.369 --> 00:17:22.640
And then there's this sort of
indentation where it dives

00:17:22.640 --> 00:17:25.000
deep into a sulcus.

00:17:25.000 --> 00:17:27.510
Comes back up, it's the next
gyrus, dives deep into the

00:17:27.510 --> 00:17:28.540
next sulcus.

00:17:28.540 --> 00:17:30.620
A huge sulcus is called
a fissure.

00:17:30.620 --> 00:17:34.020
Here's a Sylvian fissure that
separates the temporal and

00:17:34.020 --> 00:17:35.600
frontal cortices.

00:17:35.600 --> 00:17:37.900
And one of the reasons that
people have speculated about

00:17:37.900 --> 00:17:39.640
why do we have a thing
like that?

00:17:39.640 --> 00:17:44.380
Why do we have these waves of
a gyrus going up and then

00:17:44.380 --> 00:17:48.230
plunging into the depths, then
coming back up like this again

00:17:48.230 --> 00:17:52.040
and plunging from sulcus
to sulcus?

00:17:52.040 --> 00:17:53.840
And nobody really knows.

00:17:53.840 --> 00:17:55.330
But there's kind of
a speculation

00:17:55.330 --> 00:17:58.510
that's fun and plausible.

00:17:58.510 --> 00:18:03.160
One thing we know is that bigger
cortices are good, not

00:18:03.160 --> 00:18:05.050
so much one person to another,
but across species.

00:18:05.050 --> 00:18:06.820
Your smarts are in
your cortices--

00:18:06.820 --> 00:18:09.090
language, higher-level
thought, and so on.

00:18:09.090 --> 00:18:11.980
So on the whole, a species that
has bigger cortices has a

00:18:11.980 --> 00:18:14.670
lot of opportunities for
thought and social

00:18:14.670 --> 00:18:16.840
development and so on.

00:18:16.840 --> 00:18:21.380
So you could imagine having
babies with heads this big.

00:18:21.380 --> 00:18:24.850
They'd be really smart, maybe.

00:18:24.850 --> 00:18:26.555
But what would be the problem?

00:18:30.710 --> 00:18:33.830
What would be the big problem?

00:18:33.830 --> 00:18:37.240
Think about it not from your
perspective, perhaps, if most

00:18:37.240 --> 00:18:41.740
of you are sort of teenagers or
young 20s or something like

00:18:41.740 --> 00:18:43.220
that, most of you.

00:18:43.220 --> 00:18:46.900
So you don't remember your birth
experience directly.

00:18:46.900 --> 00:18:49.730
But who remembers your birth
experience pretty well?

00:18:49.730 --> 00:18:50.320
Your parents?

00:18:50.320 --> 00:18:50.820
OK.

00:18:50.820 --> 00:18:51.060
All right.

00:18:51.060 --> 00:18:53.770
It's your mother, especially.

00:18:53.770 --> 00:18:55.540
Giving birth is a
pretty painful,

00:18:55.540 --> 00:18:57.730
specific, challenging process.

00:18:57.730 --> 00:19:00.340
So if a head this big came
out, it would be

00:19:00.340 --> 00:19:01.725
incommensurate with the
birth canal that

00:19:01.725 --> 00:19:02.530
the mother can afford.

00:19:02.530 --> 00:19:04.020
It's already pretty challenging
with your head as

00:19:04.020 --> 00:19:05.550
big as it is when
it comes out.

00:19:05.550 --> 00:19:06.450
That's the challenge of birth.

00:19:06.450 --> 00:19:07.890
It's not getting the
arms and legs out.

00:19:07.890 --> 00:19:11.150
Its the head that's too big.

00:19:11.150 --> 00:19:14.060
So now we have a problem that
the mother's birth canal is

00:19:14.060 --> 00:19:14.790
only so big.

00:19:14.790 --> 00:19:17.755
We want as much brain and
smartness in our species and

00:19:17.755 --> 00:19:19.050
in ourselves as possible.

00:19:19.050 --> 00:19:20.850
So how are we going to get a
lot of neocortex in there?

00:19:23.370 --> 00:19:26.890
We're going to fold it.

00:19:26.890 --> 00:19:30.720
A lot of neocortex in there,
but a smaller volume to get

00:19:30.720 --> 00:19:32.070
out through the birth canal.

00:19:32.070 --> 00:19:35.170
And that's thought to be why the
brain has this elaborate

00:19:35.170 --> 00:19:39.180
plunging from sulcus to sulcus,
and this sort of

00:19:39.180 --> 00:19:43.620
convolved physical structure.

00:19:43.620 --> 00:19:47.070
And if we think about the brain,
we can think about

00:19:47.070 --> 00:19:49.770
things that go into our brains,
about the outer world.

00:19:49.770 --> 00:19:54.220
So when you see, vision enters
through this area, or when you

00:19:54.220 --> 00:19:55.800
hear, it enters here.

00:19:55.800 --> 00:19:58.640
When you touch or when you move
your body, these are the

00:19:58.640 --> 00:19:59.680
motor cortical neurons.

00:19:59.680 --> 00:20:02.250
So it's either sort of major
inputs or major output.

00:20:02.250 --> 00:20:02.840
That's in blue.

00:20:02.840 --> 00:20:05.900
That's the areas that are
devoted to specific perception

00:20:05.900 --> 00:20:08.320
or modalities or sensories.

00:20:08.320 --> 00:20:09.905
And then we have areas
in yellow here.

00:20:09.905 --> 00:20:11.470
They are the areas
that are sort of

00:20:11.470 --> 00:20:13.760
closely tied to one modality.

00:20:13.760 --> 00:20:16.690
But already, they're
interpreting what's going on.

00:20:16.690 --> 00:20:19.290
And then you have areas in pink
here that are sort of not

00:20:19.290 --> 00:20:23.070
tied to any modality and are
devoted to what we might call

00:20:23.070 --> 00:20:24.100
abstract thought.

00:20:24.100 --> 00:20:26.950
And you can see the prefrontal
cortex, the part of the cortex

00:20:26.950 --> 00:20:28.930
that's in front of
the motor cortex.

00:20:28.930 --> 00:20:30.510
There's a huge swath
like that.

00:20:30.510 --> 00:20:31.370
We'll come back to that.

00:20:31.370 --> 00:20:33.180
We think it's terribly important
for thinking,

00:20:33.180 --> 00:20:35.680
problem solving, and
many aspects of the

00:20:35.680 --> 00:20:39.570
highest human mentation.

00:20:39.570 --> 00:20:43.090
Now we're a huge believer in
the end that form follows

00:20:43.090 --> 00:20:44.430
function in the brain.

00:20:44.430 --> 00:20:46.250
And if we understood the correct
relationship between

00:20:46.250 --> 00:20:48.240
form and function,
we'd be very far.

00:20:48.240 --> 00:20:51.170
And a neuroanatomist named
[? Broadbent ?]

00:20:51.170 --> 00:20:53.340
made the following
heroic effort.

00:20:53.340 --> 00:20:54.830
What he did is he sectioned
brains into

00:20:54.830 --> 00:20:56.370
lots of thin slices.

00:20:56.370 --> 00:20:58.570
And he followed them through
a microscope.

00:20:58.570 --> 00:21:02.170
And every time the brain tissue
changed, the neurons

00:21:02.170 --> 00:21:06.220
looked different, he would
change the number of the area.

00:21:06.220 --> 00:21:08.880
So he started in something
like Area One.

00:21:08.880 --> 00:21:10.230
And the neurons look
pretty similar.

00:21:10.230 --> 00:21:11.570
And he's moving,
moving, moving.

00:21:11.570 --> 00:21:12.450
And then all of a sudden
they start to look

00:21:12.450 --> 00:21:13.720
different, the neurons.

00:21:13.720 --> 00:21:16.540
And then that becomes something
like Area Three.

00:21:16.540 --> 00:21:17.920
Moving, moving, Area Four.

00:21:17.920 --> 00:21:19.095
Moving, moving, Area Six.

00:21:19.095 --> 00:21:23.410
So every time the neurons looked
different to his eye,

00:21:23.410 --> 00:21:24.530
it gets a new number.

00:21:24.530 --> 00:21:27.105
The idea being when the neurons
look different, they

00:21:27.105 --> 00:21:28.380
have a different job to do.

00:21:28.380 --> 00:21:30.490
And that part of the brain
does something different.

00:21:30.490 --> 00:21:33.020
And there's lots of debates
about the best way to do this,

00:21:33.020 --> 00:21:34.090
or different interpretations.

00:21:34.090 --> 00:21:36.560
But something like this holds
true in a striking way.

00:21:36.560 --> 00:21:40.210
The cellular organization of the
brain reflects in some way

00:21:40.210 --> 00:21:42.180
what that part of the brain is
accomplishing, what part of

00:21:42.180 --> 00:21:44.150
your mind it supports.

00:21:44.150 --> 00:21:47.040
And then we have simplified
color pictures of this.

00:21:47.040 --> 00:21:50.520
And we'll come back to
neuroimaging next time.

00:21:50.520 --> 00:21:53.880
But it's turned out to have a
second life in neuroimaging.

00:21:53.880 --> 00:21:56.940
Because when scientists across
the world want to compare

00:21:56.940 --> 00:21:59.620
their neuroimaging results,
they'll talk about, well, I

00:21:59.620 --> 00:22:03.610
got activation in Area 46,
or I got it in Area 21.

00:22:03.610 --> 00:22:06.520
It's become a nomenclature for
the organization of the human

00:22:06.520 --> 00:22:09.480
brain that allows you to
integrate all kinds of imaging

00:22:09.480 --> 00:22:12.100
data about the human species.

00:22:12.100 --> 00:22:14.310
And here's a view from the
inside of the brain.

00:22:14.310 --> 00:22:16.420
And here's a structure chord,
the corpus callosum, that

00:22:16.420 --> 00:22:20.500
we'll come back to in the
next few minutes.

00:22:20.500 --> 00:22:25.790
So how much are functions
localized or distributed?

00:22:25.790 --> 00:22:26.700
How much is--

00:22:26.700 --> 00:22:28.970
you have a specific thing your
mind does, and it's in one

00:22:28.970 --> 00:22:31.600
place in the brain versus it's
spread over a range.

00:22:31.600 --> 00:22:34.110
And this idea of how much things
are distributed or

00:22:34.110 --> 00:22:36.560
localized for mental functions
in the brain has been a source

00:22:36.560 --> 00:22:38.900
of huge debate.

00:22:38.900 --> 00:22:41.130
And I'll show you a misstep,
and then I'll show you some

00:22:41.130 --> 00:22:43.510
things where we think we
have it more correctly.

00:22:43.510 --> 00:22:45.280
The misstep is a phrenology.

00:22:45.280 --> 00:22:49.240
And the most famous name
in this is from Gall.

00:22:49.240 --> 00:22:50.700
Spurzheim is another one.

00:22:50.700 --> 00:22:54.950
And in the 19th century--
that's the 1800s--

00:22:54.950 --> 00:22:56.800
the phrenology took
hold a lot.

00:22:56.800 --> 00:22:59.340
And there's a sort of
a Freudian story.

00:22:59.340 --> 00:23:01.650
If you want to call it that,
of Gall, which is that

00:23:01.650 --> 00:23:05.090
apparently when he was a
student, he viewed himself as

00:23:05.090 --> 00:23:07.750
a very effortful and fastidious
student who took

00:23:07.750 --> 00:23:09.800
all the notes you're supposed to
take, and worked very hard

00:23:09.800 --> 00:23:12.580
for exams and did everything
you were supposed to do.

00:23:12.580 --> 00:23:14.520
But shock of shocks,
some students did

00:23:14.520 --> 00:23:16.470
better than he did.

00:23:16.470 --> 00:23:17.690
And he looked around
the classroom.

00:23:17.690 --> 00:23:18.940
He said, who are these
students doing

00:23:18.940 --> 00:23:19.700
better than I am?

00:23:19.700 --> 00:23:21.050
Because I'm trying
as hard as I can.

00:23:21.050 --> 00:23:22.180
And some students are
doing better.

00:23:22.180 --> 00:23:24.360
And he said, hey, one thing I
notice about these students is

00:23:24.360 --> 00:23:26.320
they all seem to have
big foreheads.

00:23:26.320 --> 00:23:26.766
OK?

00:23:26.766 --> 00:23:27.212
[CHUCKLES]

00:23:27.212 --> 00:23:30.030
Now, I don't know how accurate
he was scientifically.

00:23:30.030 --> 00:23:32.920
But apparently, this was a
emotionally transformative

00:23:32.920 --> 00:23:33.670
moment for Gall.

00:23:33.670 --> 00:23:34.900
And you'll see in what
way this ended

00:23:34.900 --> 00:23:37.990
up guiding his science.

00:23:37.990 --> 00:23:41.560
So Gall and Spurzheim were
actually good neuroanatomists.

00:23:41.560 --> 00:23:43.680
They describe lots of things
about the brain that were

00:23:43.680 --> 00:23:46.290
correct that were kind of
unknown at the time.

00:23:46.290 --> 00:23:49.440
For example, the pyramidal
tracts, the tracts that move

00:23:49.440 --> 00:23:51.780
from your motor cortex-- say on
your left to control your

00:23:51.780 --> 00:23:54.970
right hand, or on your right
to control your left hand--

00:23:54.970 --> 00:23:58.110
they describe those very well.

00:23:58.110 --> 00:23:59.400
But here's where they
got kind of funny.

00:23:59.400 --> 00:24:01.080
They said, OK, we can describe
the physical

00:24:01.080 --> 00:24:02.090
organization of the brain.

00:24:02.090 --> 00:24:03.760
But now let's say which
part of the brain is

00:24:03.760 --> 00:24:04.990
which part of the mind.

00:24:04.990 --> 00:24:08.140
And in a way that we now
consider a bit willy-nilly,

00:24:08.140 --> 00:24:10.940
they began to assign different
mental processes to different

00:24:10.940 --> 00:24:11.660
parts of the brain.

00:24:11.660 --> 00:24:14.330
And the way they did it was they
said, I'm going to look

00:24:14.330 --> 00:24:14.820
at somebody.

00:24:14.820 --> 00:24:18.540
And let's pretend somebody you
know is very combative.

00:24:18.540 --> 00:24:20.830
What they began to
figure was this.

00:24:20.830 --> 00:24:23.190
Well, maybe the part of the
brain that's involved in being

00:24:23.190 --> 00:24:24.250
combative--

00:24:24.250 --> 00:24:27.710
the more combative you are,
the more you have of it.

00:24:27.710 --> 00:24:30.840
So if I feel your skull above
the part of the brain that I

00:24:30.840 --> 00:24:34.070
think goes with being combative,
if you have a big

00:24:34.070 --> 00:24:36.400
rise there, if I feel your
head-- and most of our heads

00:24:36.400 --> 00:24:39.410
are a little bumpy--

00:24:39.410 --> 00:24:40.830
the person who's really
combative is going to have a

00:24:40.830 --> 00:24:43.170
lot of bump there.

00:24:43.170 --> 00:24:45.960
And the person who's very
meek will have none.

00:24:45.960 --> 00:24:47.030
OK, does that make sense?

00:24:47.030 --> 00:24:48.470
They have these little
categories as they just

00:24:48.470 --> 00:24:49.630
thought about people.

00:24:49.630 --> 00:24:56.180
And they developed this idea
that they could find where

00:24:56.180 --> 00:24:59.790
cautiousness was, or
precociousness, or

00:24:59.790 --> 00:25:00.850
secretiveness.

00:25:00.850 --> 00:25:02.260
You'd give it a big
bump there.

00:25:02.260 --> 00:25:03.140
Let me show you this picture.

00:25:03.140 --> 00:25:06.440
Here's a device you would step
into that would have springs

00:25:06.440 --> 00:25:08.280
go down, and then it would go
up, and they would say, where

00:25:08.280 --> 00:25:09.170
do you have the high bumps?

00:25:09.170 --> 00:25:10.640
And where do you have
the little bumps?

00:25:10.640 --> 00:25:13.770
Now all of this is wrong.

00:25:13.770 --> 00:25:18.610
Because it's a naive way and not
a scientific way to do it.

00:25:18.610 --> 00:25:21.460
Weirdly enough, look at what
they put below the eye--

00:25:21.460 --> 00:25:23.260
language.

00:25:23.260 --> 00:25:24.930
Now that's a weird
place to put it.

00:25:24.930 --> 00:25:27.310
And what they saw was a soldier
who had a wound that

00:25:27.310 --> 00:25:30.250
went his eye and
into his brain.

00:25:30.250 --> 00:25:32.930
And they said, OK, he had
trouble producing language.

00:25:32.930 --> 00:25:34.860
And they said, well, that's
where language is.

00:25:34.860 --> 00:25:37.900
Language is not below
your eye.

00:25:37.900 --> 00:25:41.200
But they didn't realize that the
wound went up into what's

00:25:41.200 --> 00:25:42.080
something called Broca's area.

00:25:42.080 --> 00:25:43.870
We'll talk about that
in a couple minutes.

00:25:43.870 --> 00:25:46.580
And so they weren't
that wrong.

00:25:46.580 --> 00:25:48.540
They just didn't think
through where the end

00:25:48.540 --> 00:25:49.800
of the injury was.

00:25:49.800 --> 00:25:52.760
All the other ones, we
completely dismiss these days.

00:25:52.760 --> 00:25:56.380
But we have to worry about naive
ways in which we link

00:25:56.380 --> 00:25:58.770
the life of the mind to the
stuff of the brain.

00:25:58.770 --> 00:26:00.950
And they did a control
experiment. "The famous

00:26:00.950 --> 00:26:03.540
physiologist, Magendie,
preserved with veneration the

00:26:03.540 --> 00:26:04.945
brain of Laplace," who's
a big name in

00:26:04.945 --> 00:26:06.340
the history of chemistry.

00:26:06.340 --> 00:26:08.290
"Spurzheim had the natural
wish to see the brain."

00:26:08.290 --> 00:26:09.640
Spurzheim was the
phrenologist.

00:26:09.640 --> 00:26:12.330
"To test the science of
phrenologist, Magendie showed

00:26:12.330 --> 00:26:14.400
him instead the brain
of an imbecile.

00:26:14.400 --> 00:26:16.670
Spurzheim, who had already
worked up his enthusiasm,

00:26:16.670 --> 00:26:19.400
admired the brain of the
imbecile as he would have

00:26:19.400 --> 00:26:21.290
admired that of Laplace."

00:26:21.290 --> 00:26:22.350
So this was a control assess.

00:26:22.350 --> 00:26:24.030
I give you a brain of somebody
who's not a genius in

00:26:24.030 --> 00:26:25.510
chemistry, and you
go, oh my gosh.

00:26:25.510 --> 00:26:27.750
This chemistry part of the
brain is unbelievable.

00:26:27.750 --> 00:26:31.230
And this is the old idea we
talked about, that if you have

00:26:31.230 --> 00:26:34.220
an idea you believe in as a
scientist, you will always

00:26:34.220 --> 00:26:38.420
find positive evidence for
it everywhere you look.

00:26:38.420 --> 00:26:40.580
Back to the brain, and let's
talk about this part, the

00:26:40.580 --> 00:26:42.610
lower part of the orbital
frontal cortex.

00:26:42.610 --> 00:26:44.720
It sits right above your eyes.

00:26:44.720 --> 00:26:48.080
Your eyes would be something
like here.

00:26:48.080 --> 00:26:50.710
And we know something about what
that part of the brain

00:26:50.710 --> 00:26:54.070
does from the famous case
of Phineas Gage.

00:26:54.070 --> 00:26:56.920
He was involved in railroad
construction in Vermont.

00:26:56.920 --> 00:26:59.980
And that involved exploding
rocks to level the area so

00:26:59.980 --> 00:27:01.260
they could put in
train tracks.

00:27:01.260 --> 00:27:02.880
They would drill a
hole, put in some

00:27:02.880 --> 00:27:03.850
fuse, put in the powder.

00:27:03.850 --> 00:27:07.290
And they would use a tamping
iron to push down the sand and

00:27:07.290 --> 00:27:10.670
powder so there would be a big
explosion to flatten the rock.

00:27:10.670 --> 00:27:14.760
And at age 25 in 1848, he has
a mind who was described as

00:27:14.760 --> 00:27:16.640
well-balanced, energetic,
and persistent.

00:27:16.640 --> 00:27:20.970
He was the ideal employee,
resourceful, hardworking.

00:27:20.970 --> 00:27:22.880
He was made a foreman,
a leader.

00:27:22.880 --> 00:27:24.610
He was the most efficient and
capable in the group.

00:27:24.610 --> 00:27:28.970
And on September 13, 1848,
something big happened.

00:27:28.970 --> 00:27:30.420
There was a miscommunication.

00:27:30.420 --> 00:27:32.990
An iron that was three feet,
seven inches in length--

00:27:32.990 --> 00:27:35.130
I'll show you a picture in a
moment, because even if you've

00:27:35.130 --> 00:27:37.190
heard this story, until you see
a picture of it, you can't

00:27:37.190 --> 00:27:40.870
grasp how big this was compared
to a human being.

00:27:40.870 --> 00:27:43.310
There was a miscommunication,
the explosion went off early.

00:27:43.310 --> 00:27:44.710
He was directly over it.

00:27:44.710 --> 00:27:47.670
The rod flew up, went through
his head, all the

00:27:47.670 --> 00:27:48.740
way through his head.

00:27:48.740 --> 00:27:53.340
And it had the power to land 30
yards away after exploding

00:27:53.340 --> 00:27:54.860
up into the air.

00:27:54.860 --> 00:27:59.040
And by March of the next year,
he was back at work.

00:27:59.040 --> 00:28:02.200
Not too long a vacation, a
recovery period for that big a

00:28:02.200 --> 00:28:03.190
thing going through your head.

00:28:03.190 --> 00:28:06.250
But his personality had
fundamentally changed.

00:28:06.250 --> 00:28:11.130
So here's his cast of his actual
head and his skull.

00:28:11.130 --> 00:28:13.220
Here's where it shot
up through here

00:28:13.220 --> 00:28:15.660
and out this hole.

00:28:15.660 --> 00:28:17.630
Here's the actual rod
compared to that.

00:28:17.630 --> 00:28:21.330
So if you haven't seen this,
you can underestimate the

00:28:21.330 --> 00:28:23.050
amazingness of this thing.

00:28:23.050 --> 00:28:27.370
And at the time he was famous
not for the reason we now

00:28:27.370 --> 00:28:28.180
think of him.

00:28:28.180 --> 00:28:31.930
He was just a Ripley's believe
it or not story of that a

00:28:31.930 --> 00:28:34.750
human survived at all.

00:28:34.750 --> 00:28:38.120
So Antonio Damasio has attempted
to reconstruct by

00:28:38.120 --> 00:28:42.540
computer where this rod shot up
through here and out into

00:28:42.540 --> 00:28:44.250
30 yards away.

00:28:44.250 --> 00:28:46.770
They're that big compared
to him.

00:28:46.770 --> 00:28:48.970
And the amazing thing, and
described by a physician who

00:28:48.970 --> 00:28:51.580
worked with him at the time,
is "the equilibrium to his

00:28:51.580 --> 00:28:54.130
intellectual faculties and
animal propensities seems to

00:28:54.130 --> 00:28:54.630
have destroyed.

00:28:54.630 --> 00:28:57.085
He is fitful, irreverent,
indulging at times in the

00:28:57.085 --> 00:28:58.510
grossest profanity.

00:28:58.510 --> 00:29:00.360
Little deference for his
fellows, impatient of

00:29:00.360 --> 00:29:02.610
restraint, conflicting
with his desires.

00:29:02.610 --> 00:29:05.130
At times pertinaciously
obstinate, capricious and

00:29:05.130 --> 00:29:08.150
vacillating, devising many plans
of future operations,

00:29:08.150 --> 00:29:10.450
which are no sooner arranged
than they are abandoned in

00:29:10.450 --> 00:29:12.310
turn for others appearing
more feasible."

00:29:12.310 --> 00:29:14.500
Exactly the opposite of
who he was before.

00:29:14.500 --> 00:29:16.900
He was a responsible,
efficient leader.

00:29:16.900 --> 00:29:20.680
And now he's a totally
irresponsible person doing all

00:29:20.680 --> 00:29:22.110
kinds of things that
make no sense.

00:29:22.110 --> 00:29:24.710
"A child in his intellectual
capacity, he has the animal

00:29:24.710 --> 00:29:27.030
passions of a strong man."
So he completely

00:29:27.030 --> 00:29:28.090
changed who he was.

00:29:28.090 --> 00:29:31.030
In this regard, his mind was so
radically changed that his

00:29:31.030 --> 00:29:34.210
friends and acquaintances said
that "he was no longer Gage."

00:29:34.210 --> 00:29:37.540
So here's a physical insult to
the brain that changes the

00:29:37.540 --> 00:29:39.940
character of a person, that
changes what we would think of

00:29:39.940 --> 00:29:41.520
as the moral judgments.

00:29:41.520 --> 00:29:45.010
Of when is it right to tell the
truth, having plans and

00:29:45.010 --> 00:29:47.980
being a responsible, trustworthy
person, completely

00:29:47.980 --> 00:29:49.650
changed by this injury.

00:29:52.180 --> 00:29:54.860
One interpretation is this part
of the brain is essential

00:29:54.860 --> 00:29:59.210
for making moral judgments and
being of good character.

00:29:59.210 --> 00:30:01.940
What would be another
interpretation of why he might

00:30:01.940 --> 00:30:07.080
have changed, just common sense
besides that this part

00:30:07.080 --> 00:30:08.300
of the brain does that?

00:30:08.300 --> 00:30:11.620
We want to not be for
phrenologists, OK?

00:30:11.620 --> 00:30:16.140
So the first thought is, this
part of the brain supports

00:30:16.140 --> 00:30:19.400
what we think of as moral
reasoning and character.

00:30:19.400 --> 00:30:22.040
Well, what else could you
imagine might have happened?

00:30:24.980 --> 00:30:26.174
Yeah.

00:30:26.174 --> 00:30:29.443
AUDIENCE: He had a giant spike
driven though his skull and is

00:30:29.443 --> 00:30:30.377
upset about it?

00:30:30.377 --> 00:30:31.790
PROFESSOR JOHN GABRIELI: Yeah.

00:30:31.790 --> 00:30:34.220
I'll make up something
like that.

00:30:34.220 --> 00:30:37.070
But a more psychological and
different interpretation, let

00:30:37.070 --> 00:30:39.120
me try this one.

00:30:39.120 --> 00:30:41.120
He was getting ready
for the future.

00:30:41.120 --> 00:30:43.270
I'll be a foreman today, and
then next week, I'll be

00:30:43.270 --> 00:30:45.300
executive vice president, and
then I'll be associate

00:30:45.300 --> 00:30:47.170
executive president.

00:30:47.170 --> 00:30:48.610
And a rod goes through
his head, and he

00:30:48.610 --> 00:30:49.170
goes, wait a minute.

00:30:49.170 --> 00:30:49.810
Life is short.

00:30:49.810 --> 00:30:51.250
It could end at any moment.

00:30:51.250 --> 00:30:53.530
Why not just do what I want
to do all the time?

00:30:53.530 --> 00:30:57.020
Because the next rod could
come who knows when.

00:30:57.020 --> 00:31:00.110
And I had all these plans, and
I was promising people things

00:31:00.110 --> 00:31:01.670
next week that I delivered on.

00:31:01.670 --> 00:31:04.070
But that's a sucker's life,
because your life

00:31:04.070 --> 00:31:05.080
can end like that.

00:31:05.080 --> 00:31:09.710
So forget all the stuff about--
just enjoy the moment.

00:31:09.710 --> 00:31:11.160
That's a possible thing, OK?

00:31:11.160 --> 00:31:12.690
You see movies like that, where
people are told, you

00:31:12.690 --> 00:31:15.300
have so long to live,
and they change.

00:31:15.300 --> 00:31:17.800
What would you want to convince
yourself that it

00:31:17.800 --> 00:31:19.850
wasn't something like that,
which is not an unreasonable

00:31:19.850 --> 00:31:21.100
interpretation?

00:31:23.560 --> 00:31:27.120
What you would want to see, at a
minimum, is that if you have

00:31:27.120 --> 00:31:30.540
brain injuries other places in
the brain, you don't see that.

00:31:30.540 --> 00:31:32.240
And if you have other people
with brain injuries in the

00:31:32.240 --> 00:31:33.990
same part of the brain, you
see that consistently.

00:31:33.990 --> 00:31:35.100
At a minimum, you want
to say it's not

00:31:35.100 --> 00:31:37.130
just a big brain injury.

00:31:37.130 --> 00:31:39.620
But it's consistently a brain
injury in this part of the

00:31:39.620 --> 00:31:41.460
brain that leads to this
kind of behavior.

00:31:41.460 --> 00:31:43.970
And for at least this example,
that's true.

00:31:43.970 --> 00:31:46.490
Other patients with similar
injuries behaved similarly.

00:31:46.490 --> 00:31:49.750
People with very big injuries
elsewhere in the brain don't

00:31:49.750 --> 00:31:50.660
behave similarly.

00:31:50.660 --> 00:31:54.060
So there's a lot of reason in
the end for us to believe that

00:31:54.060 --> 00:31:55.640
this part of the brain is
essential for something that

00:31:55.640 --> 00:31:57.790
we consider almost
metaphysical.

00:31:57.790 --> 00:32:01.920
Character has this incredibly
physical dependence.

00:32:01.920 --> 00:32:04.280
And relatively recently, just
a few years ago, they

00:32:04.280 --> 00:32:09.700
discovered a picture of
Phineas Gage himself.

00:32:09.700 --> 00:32:11.380
Here's the rod.

00:32:11.380 --> 00:32:14.560
Here's the injury to his eye,
his eye is damaged.

00:32:14.560 --> 00:32:17.330
So one more example, and then
we'll switch this refrain.

00:32:17.330 --> 00:32:19.010
Paul Broca.

00:32:19.010 --> 00:32:22.150
And Broca's area in the brain,
here's Paul Broca.

00:32:22.150 --> 00:32:24.510
Here's a brain of a patient
named Mr. Tan.

00:32:24.510 --> 00:32:26.280
And let me say a word
about the story.

00:32:26.280 --> 00:32:29.230
So in France, a number of people
observing patients with

00:32:29.230 --> 00:32:32.140
injuries had talked about that
the left side of the brain is

00:32:32.140 --> 00:32:33.600
important for speech.

00:32:33.600 --> 00:32:35.820
Until then there had not been
much ideas that the left and

00:32:35.820 --> 00:32:38.270
right were fundamentally
different.

00:32:38.270 --> 00:32:39.700
So there's always sort of a

00:32:39.700 --> 00:32:41.390
background before the discovery.

00:32:41.390 --> 00:32:44.350
And there's a talk in 1861 which
describes a man who lost

00:32:44.350 --> 00:32:46.710
his speech but understood
everything said to him.

00:32:46.710 --> 00:32:47.660
He couldn't produce speech.

00:32:47.660 --> 00:32:48.955
He could understand speech.

00:32:48.955 --> 00:32:50.980
His intelligence is
still unimpaired.

00:32:50.980 --> 00:32:53.390
His speech is gone.

00:32:53.390 --> 00:32:55.610
And then Broca heard that talk,
and he went back, and

00:32:55.610 --> 00:32:58.360
five days later a patient named
LeBorgne, who had lost

00:32:58.360 --> 00:33:01.220
his speech-- he could only say
two things, "tan," and he

00:33:01.220 --> 00:33:03.850
could swear like crazy.

00:33:03.850 --> 00:33:07.950
And our current thought about
that is swearing that's

00:33:07.950 --> 00:33:11.150
emotional and intuitive, not the
one where you think, OK,

00:33:11.150 --> 00:33:12.640
I'm going to swear now
to scare somebody.

00:33:12.640 --> 00:33:14.530
But the one-- you stub your
toe in the middle of the

00:33:14.530 --> 00:33:16.460
night, and you really
let out a curse--

00:33:16.460 --> 00:33:18.790
we think that's guided
like an animal cry

00:33:18.790 --> 00:33:21.110
by the basal ganglia.

00:33:21.110 --> 00:33:25.610
Those heartfelt, really
emotional cursing is not

00:33:25.610 --> 00:33:26.500
really language.

00:33:26.500 --> 00:33:29.950
It's actually the same cry an
animal makes on injury.

00:33:29.950 --> 00:33:32.040
And it uses some of the
same neurocircuitry.

00:33:32.040 --> 00:33:34.500
But for higher level cortical
stuff, the only word he could

00:33:34.500 --> 00:33:37.160
say was "tan." He
died in 1871.

00:33:37.160 --> 00:33:39.470
They looked at his brain, and
they found this change in the

00:33:39.470 --> 00:33:41.190
left frontal cortex.

00:33:41.190 --> 00:33:44.410
And we now call that Broca's
aphasia, the inability to

00:33:44.410 --> 00:33:46.950
speak despite the
presence of--

00:33:46.950 --> 00:33:49.040
your mouth can move, and
you can understand

00:33:49.040 --> 00:33:49.850
language pretty well.

00:33:49.850 --> 00:33:51.140
We'll come back to that.

00:33:51.140 --> 00:33:54.080
So we talk about Broca's area,
and then Wernicke--

00:33:54.080 --> 00:33:56.890
the Broca's area's important
for production.

00:33:56.890 --> 00:33:58.900
And here's the kind of damage.

00:33:58.900 --> 00:34:02.270
And we'll come back to Broca's
aphasia later in the course.

00:34:02.270 --> 00:34:04.140
So this was a big hint that
there's something different

00:34:04.140 --> 00:34:07.740
between the right and the
left hemispheres.

00:34:07.740 --> 00:34:10.900
Now in what percentage of people
is language, especially

00:34:10.900 --> 00:34:13.770
speech production, predominantly
in the left?

00:34:13.770 --> 00:34:15.830
And our best answer for that
comes from a thing

00:34:15.830 --> 00:34:17.340
called the Wada Test.

00:34:17.340 --> 00:34:19.739
So this is a test given to
patients who are undergoing

00:34:19.739 --> 00:34:22.620
neurosurgery for something
like epilepsy,

00:34:22.620 --> 00:34:24.159
sometimes for tumors.

00:34:24.159 --> 00:34:28.050
And they want to know for you
personally with great

00:34:28.050 --> 00:34:30.780
certainty, which hemisphere is
the eloquent or speaking

00:34:30.780 --> 00:34:31.320
hemisphere?

00:34:31.320 --> 00:34:35.630
Because they want to remove more
tissue if they're away

00:34:35.630 --> 00:34:39.485
from your language areas, and
less tissue if they're near

00:34:39.485 --> 00:34:40.219
your language areas.

00:34:40.219 --> 00:34:42.290
Maybe they won't even do a
certain surgery if they're too

00:34:42.290 --> 00:34:44.360
much in the middle of
your language areas.

00:34:44.360 --> 00:34:47.449
Because in many cases, it's so
frustrating for people to lose

00:34:47.449 --> 00:34:50.730
their ability to speak their
thoughts, that they'd rather

00:34:50.730 --> 00:34:52.570
have the seizures, for
epilepsy, than

00:34:52.570 --> 00:34:54.060
be unable to speak.

00:34:54.060 --> 00:34:56.350
So physicians and neurosurgeons
are very worried

00:34:56.350 --> 00:34:57.170
about that.

00:34:57.170 --> 00:34:59.250
So what they give you is, they
give you a test where they put

00:34:59.250 --> 00:35:01.470
in a drug called
sodium amytal.

00:35:01.470 --> 00:35:04.810
And they inject it into your
femoral or carotid artery.

00:35:04.810 --> 00:35:06.140
It feeds up.

00:35:06.140 --> 00:35:08.580
And the way that the
vasculatures between the two

00:35:08.580 --> 00:35:12.340
hemispheres-- it mostly shuts
down the operation of one

00:35:12.340 --> 00:35:12.680
atmosphere.

00:35:12.680 --> 00:35:14.950
If you're injected in this
femoral artery, it'll mostly

00:35:14.950 --> 00:35:16.280
shut down your left.

00:35:16.280 --> 00:35:19.170
In this one, it will mostly
shut down your right.

00:35:19.170 --> 00:35:22.520
And while the patient has one
hemisphere turned off, and

00:35:22.520 --> 00:35:24.390
they know this because for
example, let's say they shut

00:35:24.390 --> 00:35:26.350
down this hemisphere
with the injection.

00:35:26.350 --> 00:35:27.270
You're waving your arm.

00:35:27.270 --> 00:35:29.730
It falls down because your motor
system can no longer

00:35:29.730 --> 00:35:30.650
control your arm.

00:35:30.650 --> 00:35:31.780
You're blind in this field.

00:35:31.780 --> 00:35:32.850
We'll talk about that.

00:35:32.850 --> 00:35:35.175
Many of the mental processes
done by this half of the brain

00:35:35.175 --> 00:35:36.180
are shut down.

00:35:36.180 --> 00:35:38.330
And then they'll test you like
crazy to see if you can talk.

00:35:38.330 --> 00:35:39.610
They'll say, what are the
days of the week?

00:35:39.610 --> 00:35:40.550
What's your name?

00:35:40.550 --> 00:35:41.360
Name these pictures.

00:35:41.360 --> 00:35:41.750
OK?

00:35:41.750 --> 00:35:43.420
Until the drug wears off.

00:35:43.420 --> 00:35:45.570
And then you come back two days
later or a day later, and

00:35:45.570 --> 00:35:47.230
they'll inject the other side.

00:35:47.230 --> 00:35:50.690
And they'll know with near
certainty in you which is the

00:35:50.690 --> 00:35:52.780
side of your brain that
does the speaking.

00:35:52.780 --> 00:35:57.620
And best estimates are that
something like 90% to 99% of

00:35:57.620 --> 00:35:59.260
people speak from their left.

00:35:59.260 --> 00:36:04.320
Even left-handers mostly speak
from the left hemisphere.

00:36:04.320 --> 00:36:06.230
Because these are patients with
epilepsy, we're not quite

00:36:06.230 --> 00:36:07.560
sure how they generalize
to everybody.

00:36:07.560 --> 00:36:09.080
We wouldn't do this with
typical people.

00:36:09.080 --> 00:36:12.370
Because these kinds of tests are
invasive and a bit risky.

00:36:12.370 --> 00:36:14.850
But our best estimates are that
if you're right-handed,

00:36:14.850 --> 00:36:18.320
it's almost certain you speak
from your left hemisphere.

00:36:18.320 --> 00:36:20.880
And if you're left-handed,
about 80% of left-handed

00:36:20.880 --> 00:36:23.750
people also speak from
the left hemisphere.

00:36:23.750 --> 00:36:25.250
So it doesn't go by handedness,
which makes

00:36:25.250 --> 00:36:27.910
handedness a bit more
of a mystery.

00:36:27.910 --> 00:36:33.150
So now switch from grey matter
discussions to white matter.

00:36:33.150 --> 00:36:34.630
In the middle of your
brain is something

00:36:34.630 --> 00:36:36.500
called the corpus callosum.

00:36:36.500 --> 00:36:38.190
Here it's viewed from the
middle, if we cut

00:36:38.190 --> 00:36:39.160
the brain this way.

00:36:39.160 --> 00:36:44.240
200 million myelinated fibers
that connect the similar areas

00:36:44.240 --> 00:36:45.510
from the left and the right.

00:36:45.510 --> 00:36:48.530
This is what hooks up the left
and right hemisphere

00:36:48.530 --> 00:36:50.760
from spot to spot.

00:36:50.760 --> 00:36:52.150
Here it is connecting--

00:36:52.150 --> 00:36:54.470
and this is from the side view--
so it's a huge white

00:36:54.470 --> 00:36:55.830
matter area.

00:36:55.830 --> 00:36:57.330
Corpus callosum.

00:36:57.330 --> 00:36:59.260
And people noticed it because
it was so striking.

00:36:59.260 --> 00:37:01.590
But they couldn't figure
out what it does.

00:37:01.590 --> 00:37:03.470
And it kind of started to
figure a little bit in

00:37:03.470 --> 00:37:04.860
philosophical debates.

00:37:04.860 --> 00:37:06.410
Would a divided brain--
if you cut the

00:37:06.410 --> 00:37:07.660
brain down the middle--

00:37:07.660 --> 00:37:09.500
would it read to separate
stores of mood,

00:37:09.500 --> 00:37:10.710
predisposition, knowledge,
and memory?

00:37:10.710 --> 00:37:13.060
That is, if your two halves of
your brain were divided from

00:37:13.060 --> 00:37:16.470
one other, would you be
sort of two people?

00:37:16.470 --> 00:37:18.690
Now, we're not going
to do that to you.

00:37:18.690 --> 00:37:21.590
But the fascinating thing is,
are you two people to start

00:37:21.590 --> 00:37:24.210
with, who talk to one
another sometimes

00:37:24.210 --> 00:37:26.890
across your corpus callosum?

00:37:26.890 --> 00:37:28.760
And William McDougall said,
well, the unity of

00:37:28.760 --> 00:37:31.180
consciousness does not
depend on the unity

00:37:31.180 --> 00:37:32.170
of the nervous system.

00:37:32.170 --> 00:37:34.550
And he volunteered for
commissurotomy to cut the

00:37:34.550 --> 00:37:35.880
corpus callosum.

00:37:35.880 --> 00:37:39.790
Erickson noted in 1940 that
epileptic seizures would

00:37:39.790 --> 00:37:43.640
become generalized convulsions
often in animal models--

00:37:43.640 --> 00:37:46.800
if the seizure began here,
it would spread to the

00:37:46.800 --> 00:37:49.540
corresponding part of the
opposite side of the brain,

00:37:49.540 --> 00:37:51.040
and become a much
worse seizure.

00:37:51.040 --> 00:37:53.150
So they got the idea that if
they cut the corpus callosum

00:37:53.150 --> 00:37:55.870
in patients with severe epilepsy
who did not respond

00:37:55.870 --> 00:37:58.060
to medications that maybe
that would make the

00:37:58.060 --> 00:37:59.700
seizures less severe.

00:37:59.700 --> 00:38:00.370
Does that make sense?

00:38:00.370 --> 00:38:02.460
Because you wouldn't transmit
the seizure from the left to

00:38:02.460 --> 00:38:04.760
the right or the
right to left.

00:38:04.760 --> 00:38:06.790
But people were sort of
almost making jokes

00:38:06.790 --> 00:38:08.220
about the corpus callosum.

00:38:08.220 --> 00:38:09.770
Because they couldn't figure
out what it does.

00:38:09.770 --> 00:38:11.300
They said, "The corpus callosum
is hardly connected

00:38:11.300 --> 00:38:12.680
with the psychological
functions at all.

00:38:12.680 --> 00:38:15.160
It is for transmitting seizure
activity from one hemisphere

00:38:15.160 --> 00:38:19.070
to the other." That's kind
of a neurology joke.

00:38:19.070 --> 00:38:21.170
Or Karl Lashley at Harvard,
"to keep hemispheres from

00:38:21.170 --> 00:38:24.150
collapsing into one another."
You do have to have structure

00:38:24.150 --> 00:38:25.780
to keep things from
collapsing.

00:38:25.780 --> 00:38:28.570
So now I need to tell you a
word for the next couple

00:38:28.570 --> 00:38:30.960
minutes for this to make sense,
about how your visual

00:38:30.960 --> 00:38:33.030
system is organized.

00:38:33.030 --> 00:38:35.320
So here's the world out there.

00:38:35.320 --> 00:38:37.550
And if you're looking straight
ahead, everything to the left

00:38:37.550 --> 00:38:39.650
people call the left visual
field, everything to the right

00:38:39.650 --> 00:38:41.660
people call the right
visual field.

00:38:41.660 --> 00:38:44.610
And we'll look at this more
next week a little bit.

00:38:44.610 --> 00:38:47.190
But weirdly, your eyes are
not set up in that way.

00:38:47.190 --> 00:38:49.690
You could think this eye looks
at this half, and this eye

00:38:49.690 --> 00:38:50.710
looks at that half.

00:38:50.710 --> 00:38:55.200
The way it's set up, each eye
looks at both fields.

00:38:55.200 --> 00:38:58.410
Each eye looks at both fields.

00:38:58.410 --> 00:39:02.860
And then the neurons that leave
the eye get organized

00:39:02.860 --> 00:39:04.610
here in the optic chiasm.

00:39:04.610 --> 00:39:08.530
So by the time they move out
towards the brain, everything

00:39:08.530 --> 00:39:10.830
in the opposite half of the
world is reflected.

00:39:10.830 --> 00:39:14.090
So everything that's in the
right visual field starts in

00:39:14.090 --> 00:39:15.940
your brain in the
left hemisphere.

00:39:15.940 --> 00:39:18.510
Everything that's in the left
visual field starts in your

00:39:18.510 --> 00:39:20.290
brain in the right hemisphere.

00:39:20.290 --> 00:39:21.660
Does that make sense?

00:39:21.660 --> 00:39:24.690
So the first part of your smart
neocortex that knows

00:39:24.690 --> 00:39:27.210
what's out there as you're
looking at a face, a word, a

00:39:27.210 --> 00:39:28.550
scene, anything--

00:39:28.550 --> 00:39:31.540
the right occipital cortex
notices what's on the left,

00:39:31.540 --> 00:39:34.410
and the left occipital cortex
notices on the right.

00:39:34.410 --> 00:39:37.720
Things are so seamlessly
integrated in the brain that

00:39:37.720 --> 00:39:39.230
you don't ever have
that feeling.

00:39:39.230 --> 00:39:41.230
You almost never have like,
we're getting bad signals on

00:39:41.230 --> 00:39:42.560
the left here.

00:39:42.560 --> 00:39:44.470
If you didn't have a course like
this, you wouldn't know

00:39:44.470 --> 00:39:45.080
that exists.

00:39:45.080 --> 00:39:47.050
And you could wonder, why on
Earth is it like that?

00:39:47.050 --> 00:39:50.230
Is it just to torture students
and confuse them about fields,

00:39:50.230 --> 00:39:52.390
eyes, and brains?

00:39:52.390 --> 00:39:54.240
And people debate about
some evolutionary

00:39:54.240 --> 00:39:55.020
history behind this.

00:39:55.020 --> 00:39:56.980
But it's a great big mystery--

00:39:56.980 --> 00:39:59.660
why we don't organize things
much more simply and just go

00:39:59.660 --> 00:40:01.020
all the way this way.

00:40:01.020 --> 00:40:01.700
Quite the opposite.

00:40:01.700 --> 00:40:05.130
We have in the left posterior
areas, that's where we see the

00:40:05.130 --> 00:40:06.290
right half of the world.

00:40:06.290 --> 00:40:07.790
And then things get
integrated.

00:40:07.790 --> 00:40:09.190
Is that OK?

00:40:09.190 --> 00:40:11.080
Keep in mind also that our
left hemisphere moves our

00:40:11.080 --> 00:40:12.900
right hand, and our
right hemisphere

00:40:12.900 --> 00:40:13.540
moves our left hand.

00:40:13.540 --> 00:40:15.550
So at least that's
the same story--

00:40:15.550 --> 00:40:19.170
opposite hemisphere seeing the
opposite field, controlling

00:40:19.170 --> 00:40:21.030
the opposite hand.

00:40:21.030 --> 00:40:25.500
So imagine these kinds of
patients who had the surgery

00:40:25.500 --> 00:40:28.720
that divided the corpus
callosum or

00:40:28.720 --> 00:40:30.590
treatment of epilepsy.

00:40:30.590 --> 00:40:31.410
Let me tell you a
couple things.

00:40:31.410 --> 00:40:34.030
Clinically, it was pretty
rarely done.

00:40:34.030 --> 00:40:35.200
There weren't that
many of them.

00:40:35.200 --> 00:40:37.960
It's pretty rarely done
nowadays, first.

00:40:37.960 --> 00:40:41.210
Second, the first thing that
people noticed was, it didn't

00:40:41.210 --> 00:40:43.450
have much an effect
on the patients.

00:40:43.450 --> 00:40:44.750
It's a fascinating story.

00:40:44.750 --> 00:40:48.890
Nobody noticed anything
for decades.

00:40:48.890 --> 00:40:51.790
Because they didn't have the
right questions to ask.

00:40:51.790 --> 00:40:55.320
So these patients are not like
astounding patients, I can't

00:40:55.320 --> 00:40:56.830
believe when I see them.

00:40:56.830 --> 00:40:58.920
They seem pretty much like
the same as they were.

00:40:58.920 --> 00:41:02.300
I'll show you a video in a
couple minutes of two of them.

00:41:02.300 --> 00:41:05.230
They're not looking unusual
in most ways.

00:41:05.230 --> 00:41:07.990
But when people figured out what
to ask of them, they saw

00:41:07.990 --> 00:41:08.960
remarkable things.

00:41:08.960 --> 00:41:12.980
They saw two minds
in one head.

00:41:12.980 --> 00:41:15.530
And here's how they saw that.

00:41:15.530 --> 00:41:18.560
If they showed them a picture,
let's say of a spoon and a

00:41:18.560 --> 00:41:21.300
picture of a cup simultaneously
in the two

00:41:21.300 --> 00:41:23.440
fields, they would be
up briefly and go.

00:41:23.440 --> 00:41:27.400
But it's easy for you to say, I
saw a spoon and I saw a cup.

00:41:27.400 --> 00:41:29.340
They would say, what
did you see?

00:41:29.340 --> 00:41:32.240
And the person would
say, a cup.

00:41:32.240 --> 00:41:34.610
And that would be it.

00:41:34.610 --> 00:41:35.300
What did you see?

00:41:35.300 --> 00:41:35.710
A cup.

00:41:35.710 --> 00:41:40.170
Because the information in the
right visual field goes into

00:41:40.170 --> 00:41:41.730
the left hemisphere.

00:41:41.730 --> 00:41:43.560
That's the speaking
hemisphere.

00:41:43.560 --> 00:41:47.630
So left hemisphere says,
I saw a cup.

00:41:47.630 --> 00:41:50.780
The right hemisphere saw
this perfectly well.

00:41:50.780 --> 00:41:53.420
It's typically not the
speaking hemisphere.

00:41:53.420 --> 00:41:57.040
So that information is locked
in the right hemisphere, and

00:41:57.040 --> 00:41:59.710
it doesn't have access to the
speaking part of the brain in

00:41:59.710 --> 00:42:00.730
the left hemisphere.

00:42:00.730 --> 00:42:03.670
So each hemisphere had its own
experience, and only the left

00:42:03.670 --> 00:42:05.150
hemisphere could speak.

00:42:05.150 --> 00:42:08.260
You would integrate this
information instantly via the

00:42:08.260 --> 00:42:10.000
corpus callosum.

00:42:10.000 --> 00:42:12.690
But each hemisphere only
knew what it saw.

00:42:12.690 --> 00:42:16.340
And so here's another example,
which is not only that each

00:42:16.340 --> 00:42:17.870
hemisphere only knows
what it knows.

00:42:17.870 --> 00:42:19.400
But it's completely
ignorant that the

00:42:19.400 --> 00:42:21.170
other one knows anything.

00:42:21.170 --> 00:42:25.220
It's as if the two of you were
sitting next to each other and

00:42:25.220 --> 00:42:26.810
don't know each other,
are not passing notes

00:42:26.810 --> 00:42:29.790
or tweeting or whatever.

00:42:29.790 --> 00:42:32.220
It's as if like, do you know
exactly what the person next

00:42:32.220 --> 00:42:33.450
to you is thinking?

00:42:33.450 --> 00:42:35.260
No, not necessarily.

00:42:35.260 --> 00:42:37.640
So that's exactly what it is
like, like you're in one

00:42:37.640 --> 00:42:39.560
person in their brain,
in their skull.

00:42:39.560 --> 00:42:42.270
So they would show them a square
in the left visual

00:42:42.270 --> 00:42:44.480
field and a triangle in the
right visual field.

00:42:44.480 --> 00:42:46.150
You would say, I saw a square,
I saw a triangle.

00:42:46.150 --> 00:42:47.710
What do you want?

00:42:47.710 --> 00:42:48.780
Here's what happens.

00:42:48.780 --> 00:42:51.880
If they're asked to say,
say what did you see?

00:42:51.880 --> 00:42:55.590
And then behind a board,
draw what you saw.

00:42:55.590 --> 00:42:58.970
The board is there so it's
not confusing them.

00:42:58.970 --> 00:42:59.660
So here's what they say.

00:42:59.660 --> 00:43:00.180
What did you see?

00:43:00.180 --> 00:43:01.090
I saw a triangle.

00:43:01.090 --> 00:43:03.060
Because it's in the right field,
it goes into their

00:43:03.060 --> 00:43:04.800
visual area in the
left hemisphere.

00:43:04.800 --> 00:43:06.810
That's the speaking
hemisphere.

00:43:06.810 --> 00:43:08.930
But if they're drawing
with their left hand,

00:43:08.930 --> 00:43:11.190
what do they draw?

00:43:11.190 --> 00:43:12.520
The square.

00:43:12.520 --> 00:43:15.000
Because the right hemisphere saw
a square, so the left hand

00:43:15.000 --> 00:43:16.160
is drawing, it draws
the square.

00:43:16.160 --> 00:43:19.270
So simultaneously they will say,
a triangle, and the hand

00:43:19.270 --> 00:43:21.590
behind the board will
draw a square.

00:43:21.590 --> 00:43:25.280
And the patient is not bothered
in the least.

00:43:25.280 --> 00:43:27.950
Because each hemisphere only
knows what it knows.

00:43:27.950 --> 00:43:31.640
The reason they have the board
there is if they didn't have

00:43:31.640 --> 00:43:33.220
the board there, then the left
hemisphere would see you

00:43:33.220 --> 00:43:34.320
drawing a square.

00:43:34.320 --> 00:43:35.800
And you go like, why am
I drawing a square?

00:43:35.800 --> 00:43:36.720
I saw a triangle.

00:43:36.720 --> 00:43:37.940
And the person would
be weirded out.

00:43:37.940 --> 00:43:39.190
Does that make sense?

00:43:42.010 --> 00:43:43.010
But here's the thing.

00:43:43.010 --> 00:43:46.570
The amazing thing is both of
them have a lot of smarts by

00:43:46.570 --> 00:43:47.180
themselves.

00:43:47.180 --> 00:43:49.120
And they're completely
unaware of what the

00:43:49.120 --> 00:43:50.620
other hemisphere knows.

00:43:50.620 --> 00:43:52.960
Again, the idea is in you,
the hemispheres are

00:43:52.960 --> 00:43:53.710
talking all the time.

00:43:53.710 --> 00:43:55.630
But at lots of moments,
different parts of your brain

00:43:55.630 --> 00:43:57.270
might be knowing different
things.

00:43:57.270 --> 00:43:58.680
And we have a lot of
belief for that.

00:43:58.680 --> 00:44:00.690
But this is the most striking
demonstration.

00:44:00.690 --> 00:44:04.230
So here's a patient who was
asked to say what he saw and

00:44:04.230 --> 00:44:05.156
pick it up.

00:44:05.156 --> 00:44:06.980
He had one instruction.

00:44:06.980 --> 00:44:10.640
Read what you see, and pick
it up with your left hand.

00:44:10.640 --> 00:44:12.280
So he sees the word ring.

00:44:12.280 --> 00:44:14.620
In the speaking hemisphere,
he says ring.

00:44:14.620 --> 00:44:17.250
His left hemisphere sees the
word key, has enough language

00:44:17.250 --> 00:44:18.040
to read that.

00:44:18.040 --> 00:44:20.925
And it picks up the key
behind the board.

00:44:20.925 --> 00:44:23.980
And it never says, I saw two
things or anything like that

00:44:23.980 --> 00:44:25.660
in most cases.

00:44:25.660 --> 00:44:29.630
So let me stop here.

00:44:29.630 --> 00:44:31.570
And can we do the first video?

00:44:31.570 --> 00:44:33.970
So you're going to see an
example of a patient named

00:44:33.970 --> 00:44:37.760
Vicky who's going to be tested
by Mike Gazzaniga.

00:44:37.760 --> 00:44:39.890
You're going to see two videos
with Mike Gazzaniga when he

00:44:39.890 --> 00:44:40.720
was younger and when
he was older.

00:44:40.720 --> 00:44:42.870
He did a lot of the work with
these split brain patients.

00:44:42.870 --> 00:44:45.820
Plus, Alan Alda from MASH will
visit Mike Gazzaniga in the

00:44:45.820 --> 00:44:47.070
second one.

00:44:58.600 --> 00:45:01.040
So one of the really interesting
things is these

00:45:01.040 --> 00:45:03.810
split brain patients have given
us a chance to ask, you

00:45:03.810 --> 00:45:07.000
and I, what are some different
ways in which the right

00:45:07.000 --> 00:45:09.395
hemisphere and left hemisphere
are your own minds?

00:45:09.395 --> 00:45:12.141
And what are the things they
seem to care about, and that

00:45:12.141 --> 00:45:13.300
are useful?

00:45:13.300 --> 00:45:14.425
So here's one example
from Jerre Levy.

00:45:14.425 --> 00:45:16.250
It's a very clever experiment.

00:45:16.250 --> 00:45:18.600
She would show in the left
or right visual field

00:45:18.600 --> 00:45:20.330
something like this.

00:45:20.330 --> 00:45:24.060
And then say, in free view,
which of these two things is

00:45:24.060 --> 00:45:25.340
more similar?

00:45:25.340 --> 00:45:28.630
And on purpose it's ambiguous.

00:45:28.630 --> 00:45:30.850
On purpose you could say, well,
this is more similar

00:45:30.850 --> 00:45:33.630
because it has a similar
shape or appearance.

00:45:33.630 --> 00:45:36.600
This is more similar because I
use a spoon and a fork to eat

00:45:36.600 --> 00:45:38.470
a piece of cake.

00:45:38.470 --> 00:45:42.390
And if this was seen by the left
hemisphere, people would

00:45:42.390 --> 00:45:44.450
pick by function.

00:45:44.450 --> 00:45:47.440
If this was seen by the right
hemisphere, the patients would

00:45:47.440 --> 00:45:49.770
pick by appearance.

00:45:49.770 --> 00:45:53.460
So the ideas is that the left--
and this is the power

00:45:53.460 --> 00:45:56.590
of having two hemispheres in
parallel figuring out what's

00:45:56.590 --> 00:46:00.480
going on-- one is figuring out
what's the information I need

00:46:00.480 --> 00:46:02.930
about shape and things like
that in the world?

00:46:02.930 --> 00:46:05.160
And what's the information
I need about function?

00:46:05.160 --> 00:46:08.230
And because you have two
semi-independent brains in

00:46:08.230 --> 00:46:11.840
you, you're constantly figuring
out form and function

00:46:11.840 --> 00:46:14.430
and then using whatever you
need to use to solve the

00:46:14.430 --> 00:46:15.720
problem in front of you.

00:46:15.720 --> 00:46:16.780
Does that make sense?

00:46:16.780 --> 00:46:17.990
So here's another nice one.

00:46:17.990 --> 00:46:21.390
Here's scissors projected
into left visual field.

00:46:21.390 --> 00:46:24.280
The right hemisphere,
that would pick the

00:46:24.280 --> 00:46:24.990
spoon and the fork.

00:46:24.990 --> 00:46:27.940
Because the crossing shape
is resembling that.

00:46:27.940 --> 00:46:30.980
In the right visual field, left
hemisphere, people would

00:46:30.980 --> 00:46:32.360
pick the needle and thread.

00:46:32.360 --> 00:46:34.090
Because that functionally
goes with scissors.

00:46:34.090 --> 00:46:37.740
So your mind is seeing the same
thing, but in one case

00:46:37.740 --> 00:46:40.570
it's tuned, in the left
hemisphere, to functions, and

00:46:40.570 --> 00:46:43.110
the right hemisphere
to appearance.

00:46:43.110 --> 00:46:46.050
So these are just notes for you
going over what I said.

00:46:46.050 --> 00:46:49.240
So they talked about, would
you have two different

00:46:49.240 --> 00:46:50.190
consciousnesses in you?

00:46:50.190 --> 00:46:51.730
It's hard really to tell.

00:46:51.730 --> 00:46:53.740
They did one experiment with
Vicky, where they would

00:46:53.740 --> 00:46:56.150
present a nude picture in
the left visual field

00:46:56.150 --> 00:46:56.836
unexpectedly--

00:46:56.836 --> 00:46:59.790
and this was a long time ago,
it was a shocking thing.

00:46:59.790 --> 00:47:01.920
And the patient would
blush and giggle.

00:47:01.920 --> 00:47:05.480
When asked to explain why you
were blushing and giggling,

00:47:05.480 --> 00:47:08.680
all she could say is, oh doctor,
you have some machine.

00:47:08.680 --> 00:47:10.780
She knows something funny
happened and inappropriate.

00:47:10.780 --> 00:47:13.270
She can't tell you just in the
language in the hemisphere

00:47:13.270 --> 00:47:13.820
that saw it.

00:47:13.820 --> 00:47:16.120
And so she gives this other
kind of description.

00:47:16.120 --> 00:47:18.320
Another kind of a favorite
one is the dresses one.

00:47:18.320 --> 00:47:21.120
There was one patient who went
back to work in his father's

00:47:21.120 --> 00:47:21.870
grocery store.

00:47:21.870 --> 00:47:25.430
And this could be frustrating,
early on after his treatment.

00:47:25.430 --> 00:47:28.300
He would stock things onto a
shelf with one hand and remove

00:47:28.300 --> 00:47:28.860
it with the other.

00:47:28.860 --> 00:47:31.870
You could imagine that would
be a slow work day.

00:47:31.870 --> 00:47:34.630
These kinds of weird behaviors
pretty much

00:47:34.630 --> 00:47:36.240
clear up within weeks.

00:47:36.240 --> 00:47:38.480
After that, you have to test
to see the difference.

00:47:38.480 --> 00:47:40.830
Another one, they presented
the instructions -- walk

00:47:40.830 --> 00:47:43.090
across the room to the left
visual field, right

00:47:43.090 --> 00:47:43.480
hemisphere.

00:47:43.480 --> 00:47:45.600
Person gets up, walks
across the room.

00:47:45.600 --> 00:47:48.190
That person's asked, why did
you walk across the room?

00:47:48.190 --> 00:47:49.490
Person doesn't know why.

00:47:49.490 --> 00:47:52.090
Because their speaking
hemisphere didn't see it.

00:47:52.090 --> 00:47:53.930
And they'll just say something
like, I was thirsty.

00:47:53.930 --> 00:47:56.260
So interestingly, they
fill in motivations.

00:47:56.260 --> 00:47:59.050
They don't say, I don't know
why, or I have a split brain.

00:47:59.050 --> 00:48:00.940
What do you expect?

00:48:00.940 --> 00:48:03.080
I mean they're being tested
for that, right?

00:48:03.080 --> 00:48:05.290
But they seem like they want
to fill in some other

00:48:05.290 --> 00:48:05.770
explanation.

00:48:05.770 --> 00:48:07.830
And I'll show you another
example for that.

00:48:07.830 --> 00:48:09.440
And social psychologists
have said--

00:48:09.440 --> 00:48:10.810
because they like this--

00:48:10.810 --> 00:48:13.870
they said, this is an example
that people are desperate

00:48:13.870 --> 00:48:15.240
rationalizers for ourselves.

00:48:15.240 --> 00:48:17.220
We'll come back to this
in social psychology.

00:48:17.220 --> 00:48:19.620
You could think about whether
it's true for yourself or not.

00:48:19.620 --> 00:48:22.360
That when things are
contradictory, we don't say,

00:48:22.360 --> 00:48:23.810
oh, things are contradictory.

00:48:23.810 --> 00:48:28.240
We say, well, here's why, as we
explain our own behavior,

00:48:28.240 --> 00:48:31.370
that we have to rationalize
our own behavior.

00:48:31.370 --> 00:48:33.720
So here's the example.

00:48:33.720 --> 00:48:34.650
Here's the picture.

00:48:34.650 --> 00:48:36.830
So here's a split
brain patient.

00:48:36.830 --> 00:48:44.930
And he's shown pairs of pictures
in visual fields.

00:48:44.930 --> 00:48:46.900
And he's supposed to pick two
of them in free vision, then

00:48:46.900 --> 00:48:49.890
relate to what he sees.

00:48:49.890 --> 00:48:51.010
Here's the picture
that he sees.

00:48:51.010 --> 00:48:53.490
Boom, this goes up
and goes away.

00:48:53.490 --> 00:48:57.180
Now both hands go and pick
something related to what the

00:48:57.180 --> 00:48:58.450
person just saw.

00:48:58.450 --> 00:49:00.420
OK So this is shown briefly.

00:49:00.420 --> 00:49:01.860
It disappears.

00:49:01.860 --> 00:49:03.860
This hand--

00:49:03.860 --> 00:49:05.770
let me do this right--

00:49:05.770 --> 00:49:07.610
the chicken went to this
part of the brain that

00:49:07.610 --> 00:49:08.480
controls this hand.

00:49:08.480 --> 00:49:12.130
So the claw goes
to the rooster.

00:49:12.130 --> 00:49:15.372
This hemisphere saw a snowy
scene, controls this hand and

00:49:15.372 --> 00:49:18.290
it goes for the shovel.

00:49:18.290 --> 00:49:20.620
So now they're going to make
the patient confront the

00:49:20.620 --> 00:49:23.820
weirdness of what he just did.

00:49:23.820 --> 00:49:24.780
His hand went out.

00:49:24.780 --> 00:49:27.010
Each hemisphere points
to what it saw.

00:49:27.010 --> 00:49:29.480
And again, his answer could
be, I'm in an experiment.

00:49:29.480 --> 00:49:30.850
You're constantly tricking me.

00:49:30.850 --> 00:49:31.720
I know that.

00:49:31.720 --> 00:49:34.790
Basically they know that,
they're in an experiment.

00:49:34.790 --> 00:49:37.480
But his answer is,
I saw a claw--

00:49:37.480 --> 00:49:38.780
that's the speaking
hemisphere.

00:49:38.780 --> 00:49:39.980
I picked the chicken.

00:49:39.980 --> 00:49:43.880
OK, that's fine, left hemisphere
is speaking.

00:49:43.880 --> 00:49:45.050
And then you have
to clean out the

00:49:45.050 --> 00:49:46.820
chicken shed with a shovel.

00:49:46.820 --> 00:49:48.210
OK You understand?

00:49:48.210 --> 00:49:54.210
He's creating a story to make
his behavior seem coherent.

00:49:54.210 --> 00:49:56.890
Rather than just saying, I'm
an experimental subject and

00:49:56.890 --> 00:49:58.700
that's why you're testing me.

00:49:58.700 --> 00:50:00.490
Here's the last thing I want to
show you for two minutes.

00:50:00.490 --> 00:50:02.630
And then I'm going to show you
a film that touches on this.

00:50:02.630 --> 00:50:05.740
Psychologists are interested in
understanding also in what

00:50:05.740 --> 00:50:08.460
way we see the forests
and the trees.

00:50:08.460 --> 00:50:12.230
You see the bumper stickers,
think globally, act locally.

00:50:12.230 --> 00:50:15.560
Let's talk about global and
local, or parts and wholes.

00:50:15.560 --> 00:50:19.510
So the whole here is H. And the
locals are S. Does that

00:50:19.510 --> 00:50:20.000
makes sense?

00:50:20.000 --> 00:50:24.440
It's a way to operationalize an
experiment looking at the

00:50:24.440 --> 00:50:27.190
forest versus the
trees of S's.

00:50:27.190 --> 00:50:31.500
Here the whole is the C, and
the local elements are O's.

00:50:31.500 --> 00:50:34.290
And there's a painter who
did beautiful pictures.

00:50:34.290 --> 00:50:35.990
You'll see another example.

00:50:35.990 --> 00:50:40.370
But he made whole faces out
of vegetable parts.

00:50:40.370 --> 00:50:41.760
OK, do you see that?

00:50:41.760 --> 00:50:44.940
Every part here of this face,
if you look at it piece by

00:50:44.940 --> 00:50:49.540
piece, is a different
vegetable or fruit.

00:50:49.540 --> 00:50:51.770
So it's a sort of play on this
thing, and you'll see the

00:50:51.770 --> 00:50:52.400
movie that way.

00:50:52.400 --> 00:50:54.980
He made the whole face
of the parts of this.

00:50:54.980 --> 00:50:57.360
But here's what split
brain patients do.

00:50:57.360 --> 00:50:58.810
And I'll show you something
else in a moment.

00:50:58.810 --> 00:51:02.280
They're asked shortly after
surgery to copy this.

00:51:02.280 --> 00:51:04.970
It's right in front of
them all the time.

00:51:04.970 --> 00:51:06.300
It's right in front of
them all the time.

00:51:06.300 --> 00:51:09.100
Just copy what's right
in front of you.

00:51:09.100 --> 00:51:12.190
If they do it with their left
hand, right hemisphere, you

00:51:12.190 --> 00:51:15.830
see that you get the forest
but not the trees.

00:51:15.830 --> 00:51:16.740
Here's the trees, and
then they don't

00:51:16.740 --> 00:51:18.710
look that good, honestly.

00:51:18.710 --> 00:51:23.360
But still, there's some
Y-ish thing there.

00:51:23.360 --> 00:51:24.010
Copy this.

00:51:24.010 --> 00:51:24.890
It's right in front of you.

00:51:24.890 --> 00:51:27.870
If it's the left hand, you get
the forest but not the parts.

00:51:27.870 --> 00:51:29.620
If it's the right hand,
you get the

00:51:29.620 --> 00:51:31.050
parts but not the forest.

00:51:31.050 --> 00:51:31.890
Does that make sense?

00:51:31.890 --> 00:51:34.530
It's as if each hemisphere is
one hemisphere-- the left

00:51:34.530 --> 00:51:37.240
hemisphere is seeing the
parts, and the right

00:51:37.240 --> 00:51:38.830
hemisphere is seeing
the whole.

00:51:38.830 --> 00:51:39.660
So that's awesome.

00:51:39.660 --> 00:51:41.850
Because you don't have to
be global or local.

00:51:41.850 --> 00:51:45.970
Your mind is simultaneously
figuring out the local parts

00:51:45.970 --> 00:51:47.270
and the global parts.

00:51:47.270 --> 00:51:50.010
And then you can use whatever
is the useful information.

00:51:50.010 --> 00:51:53.870
Your mind, because you have
multiple brains in you, is

00:51:53.870 --> 00:51:55.790
sort of figuring out what
it needs to do.

00:51:55.790 --> 00:51:58.690
Last thing I'll show you, and
then we'll do one more video.

00:51:58.690 --> 00:52:03.370
Here are patients who have
injuries after stroke.

00:52:03.370 --> 00:52:04.670
It's the same idea, though.

00:52:04.670 --> 00:52:06.390
So here's what they
have to copy.

00:52:06.390 --> 00:52:07.770
It's right in front of them.

00:52:07.770 --> 00:52:08.960
Just copy it exactly.

00:52:08.960 --> 00:52:10.350
That's all they have to do.

00:52:10.350 --> 00:52:16.970
If the patient has damage on the
right, he loses his sense

00:52:16.970 --> 00:52:18.540
of wholeness.

00:52:18.540 --> 00:52:21.890
You see there's lots of Z's,
that's the parts perceived by

00:52:21.890 --> 00:52:23.580
the intact left hemisphere.

00:52:23.580 --> 00:52:25.400
But the right hemisphere
is not giving very much

00:52:25.400 --> 00:52:28.010
information about the whole.

00:52:28.010 --> 00:52:30.540
Here's another patient with
left hemisphere damage.

00:52:30.540 --> 00:52:32.940
That person fails to appreciate
the parts,

00:52:32.940 --> 00:52:33.770
but gets the whole.

00:52:33.770 --> 00:52:35.210
Here's the same thing
down here.

00:52:35.210 --> 00:52:37.990
A patient with right hemisphere
damage appreciates

00:52:37.990 --> 00:52:42.440
the parts in the intact left
hemisphere, but doesn't

00:52:42.440 --> 00:52:45.910
appreciate the whole in the
injured right hemisphere.

00:52:45.910 --> 00:52:48.680
Conversely, here's the injured
left hemisphere.

00:52:48.680 --> 00:52:50.110
That patient copies the whole.

00:52:50.110 --> 00:52:51.900
The right hemisphere gets
it, left hemisphere

00:52:51.900 --> 00:52:54.820
is missing the parts.

00:52:54.820 --> 00:52:55.820
The amazing thing?

00:52:55.820 --> 00:52:57.220
It's right in front of them.

00:52:57.220 --> 00:52:58.430
They're copying it.

00:52:58.430 --> 00:53:02.820
But if your brain is injured, it
no longer appreciates that

00:53:02.820 --> 00:53:06.580
the whole exists or that
a part exists.

00:53:06.580 --> 00:53:08.880
It's as if it wasn't there.

00:53:08.880 --> 00:53:10.720
So that's how much our mind
is what our brain

00:53:10.720 --> 00:53:12.030
does in this regard.

00:53:12.030 --> 00:53:14.110
And so if we do the last video
you'll see that again.

00:53:25.288 --> 00:53:27.250
Any questions on what you saw?

00:53:27.250 --> 00:53:29.860
So I would say neurons
are unbelievably--

00:53:29.860 --> 00:53:31.730
we can't even begin to
figure out your brain

00:53:31.730 --> 00:53:32.560
at the neuron level.

00:53:32.560 --> 00:53:34.740
We're so far from that.

00:53:34.740 --> 00:53:37.410
The big message from this last
part besides hemispheric

00:53:37.410 --> 00:53:40.420
specialization is that
your brain--

00:53:40.420 --> 00:53:41.660
and we'll show you this
over and over

00:53:41.660 --> 00:53:42.790
again in this course--

00:53:42.790 --> 00:53:46.840
is a society of semi-independent
brains doing

00:53:46.840 --> 00:53:50.500
their own thing, sharing
information as needed.

00:53:50.500 --> 00:53:53.400
And the more we study the brain,
the more we understand

00:53:53.400 --> 00:53:56.860
how many parts of you there are
that are semi-independent

00:53:56.860 --> 00:53:57.860
and autonomous.

00:53:57.860 --> 00:53:59.110
Thanks.