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PROFESSOR: Good afternoon.
In the last lecture we talked
about the remarkable human
brain, and how it empowers our
thoughts, or feelings, or
desires, or actions in the
world, and how we began to
understand this remarkable
complexity, or at least grasp
something of the complexity.
How we understand the potential
for things like
moral character,
and judgments.
The case of Phineas Gage, to
produce language, to speak our
feelings and thoughts that's
blocked in a patient like
Broca's patient, with
Broca's aphasia.
We talked about the fact that
split brain patients show us
not only to the left and right
hemispheres of the human brain
mediate separate mental
abilities, but that they also
seem to have almost independent
forms of
consciousness, or they
don't have to be
aware of one another.
And so my focus today is to say
we would learn from very
unusual clinical cases.
And I'm going to focus today on
tools we have to study the
typical human brain.
And what is it that we can do to
understand how your brain--
without having a
hemispherectomy or a big stroke--
how does it operate, and what
are the principles of human
brain function they gave
rise to the human mind?
So what are the ways we can
learn about the human brain?
And one thing we can't do is
when animal researchers can
do, we can't literally go inside
the brain except in
very rare clinical situations.
I'll talk about them, but it's
a rare source of evidence.
So there's a million ways in
which are trying to understand
which part of the brain is which
part of the mind, and we
talked about the fact that
phronology was a big misstep
in assigning the functions of
mental life to different parts
of the brain.
And so we hope we can do
a bit better than that.
And I'm going to review with
you today some of the core
methods, and there's
a number of them
studying the human brain.
The reason there's a number
is none of them
are the magic answer.
All of them are limited in their
own ways, and we sort of
need all of them to begin
to grasp how your
brain makes your mind.
There's three huge ways in which
we now have the human
brain organized.
Lesions, injuries to the brain,
stimulation when you're
allowed to stimulate
the brain--
rarer, but we'll talk
about that.
And the most common, the one you
see all the time in books
and magazines, recording,
functional MRI, EEG, methods
where we record brain
activity, and try to
understand how that relates to
the life of the human mind.
And so we're going to go through
these things a little
bit and show you how they're
applied in some ways that I
hope that you'll find
interesting.
We'll come back to many of these
things as we go through
the semester, and as we talk
about aging, or child
development, or personality,
or other
topics, social cognition.
We'll use these tools to
understand the brain bases of
those kinds of aspects
of our mental lives.
So what's a big injury
you can have?
You can have a stroke, where
tissue in the brain no longer
receives its vascular supply
that it depends on so greatly.
And a lot of different things
like hypoxia, lack of oxygen,
the brain is very sensitive
to oxygen.
Tumors can grow, you could have
degenerative disorders
like Alzheimer's, Huntington's,
Parkinson's, and
others, epilepsy.
So there's lots of different
ways in which you can end up
with brain injury, and
ultimately neuronal death.
What's the strength of this
form of evidence?
Well first of all,
it's causal.
We've talked about the
difference between causal and
correlational sources of
evidence, causal ones be more
powerful for scientific
explanation.
A certain part of the brain is
injured in you no longer can
speak, you change your
character, you no longer can
make memories.
We're pretty sure that part of
the brain in some way is
required, or causal, for
that part of your
mental life to operate.
The deficits you see following
brain injuries can be amazing,
we talked about Phineas Gage
changing his character, unable
to produce language, unable
to make new memories.
We'll talk a little bit about
patients with Prosopagnosia,
it's a good big word to go home
on spring break and if
your parents ask what have you
learned about, you say
Prosopagnosia.
That just means a deficit
in recognizing faces.
Patients with Prosopagnosia will
be unable to recognize
their own spouse
by their face.
They'll recognize it by the
voice, by the physical
movements, but not
by their face.
We learn amazing things about
the brain that until it
happens we didn't know that
could happen, what people like
to call counterintuitive.
So we'll talk later in the
course in a couple times about
blindsight, patients who say,
I see nothing, but their
behavior shows some part of
their brain sees something.
We'll talk about category
specific deficits where
patients all of the sudden can
no longer name living things,
but they can name nonliving
things.
So you wouldn't have
thought of that if
you didn't see that.
And we get separations
in the brain
between different things.
We talked about the difference
between the left hemisphere
being important for
local features,
the right for global.
The left thinking in terms of
functional things in the
world, the right in terms
of appearances.
We talked about that already.
We'll talk about other things,
the hippocampus is important
for knowing that, knowing a
piece of information but the
Basal Ganglia is important for
learning how to do things,
mental skills and
physical skills.
We'll come back to all of those,
it gives us way to
organize things.
Much of our most solid
understanding of the human
brain still comes from
the history of
neurology and lesions.
But what are its limitations?
First, brain injuries don't
follow anatomical boundaries,
they sort of crossover things
depending on the injury.
So they're not going to
selectively damage one part of
the brain and not touch an
adjacent one they could be
doing something different.
People can be variable
in their response.
Nearby systems, if you have two
things in the brain that
are next door to one another,
do quite different things.
Injuries are likely to injure
them both, and you will have a
wrong conclusion about
the architecture
of the human brain.
When we test a patient and ask
them to do things after a
brain injury, we don't really
test the part of the brain
that's not there.
We really test a part of the
brain that is there, people do
the best they can.
So there's secondary
degeneration to an injury,
there's recovery from
injury, there's
compensation from an injury.
When you test a patient with a
brain injury, you're testing
what the rest of the brain can
do in the absence of one of
its companions.
And finally can offer
limited views of
normal brain function.
Let me pick one and we'll
come back in the course.
We're very interested in
variation in people--
individuality--
what's the neurology
of individuality?
That's very hard to study in
lesion cases, because we don't
see enough of a lesion.
we don't have enough Phineas
Gages to ask would that injury
look different if you grew up in
one culture or another, if
you were outgoing versus shy.
Those kinds of things
are very hard to
answer patient by patient.
But we can test large groups of
people with imaging and ask
what's the influence of
culture on your brain
organization?
What's the influence of
personality on how your
brain's organized?
And you'll see later on in the
semester evidence about those
sorts of things.
So let's go back to Paul Broca,
the neurologist who
they gave a name to Broca's
area, because he sought a
patient like this,
like [INAUDIBLE].
That this patient had a big
injury in this area could no
longer speak.
And every course you ever take
about the brain almost will
include a discussion
about Broca's area.
So I'm going to warp your world
in a very narrow way,
but maybe a shocking way, and
tell you we don't even know
how to think about Broca's
area once we get more
scientific than that.
So because this is MIT
so we're willing to
tell the truth, OK.
So some years later Nina
Dronkers said the following
thing, she studied a large
group of patients who had
Broca's aphasia by behavior.
That is they had trouble
speaking, but the
comprehension was pretty good.
And then she made maps of
their injuries and she
overlaid those maps.
And she said who has Broca's
aphasia, and if you have
Broca's aphasia, what's the
one part of the brain that
every patient with Broca's
aphasia has damage to.
Because these patients--
what you see on these maps is,
some patients have damage
here, or here, or here.
But you line them all up and you
say, what's the one spot
that you have to have injured
to have Broca's aphasia?
And it's not this area that you
saw in the picture, it's
this area, in yellow, an area
called the Precentral Gyrus of
the Insula.
The Insula is a fascinating,
mysterious little structure--
you have one on the left,
and one on the right--
that runs along from the
temporal lobe, up to the
frontal cortex.
Just a couple years ago there
was a paper reporting that
patients who had stroke in
posterior insula instantly
gave up smoking, and never
wanted to smoke again.
There's huge research efforts
to help people quit smoking,
just because it's such a
difficult health problem.
Nobody is doing insula lesions
to help people
stop smoking, OK.
But it just stopped the smoking,
and their desire to
smoke, just like that.
This is now more towards the
front of the brain, this is
not what anybody in a book or
a course will tell you is
Broca's area, that's out here.
But it turns out this is the hot
spot, and you could say,
well what about the
original patient?
So kind of creatively Nina
Dronkers went back and they
did an MRI of the brain of the
deceased original Broca's
aphasic patient.
They still had his brain, they
put it in a scanner and they
ran a structural MRI.
And what they found was sure
enough he had damage way
inside the exterior limit of
this damage, in as well as in
white matter that
connects to it.
So even now imaging evidence
lets us rediscover what is the
true basis of your ability
to speak, or its
vulnerability to injury.
And it turns out not
to be exactly what
Broca thought it was.
He saw big lesion and he said,
this is the part of matters.
It turns out, as far as we
understand, it's a slightly
different part that he thought
was just at the
edge and not important.
So we can get better even going
back to 150 years of
imaging a brain, we don't have
many of those brains around.
Stimulation, so you like to go
in the brain is stimulate.
People who do animal work will
go in and stimulate a neuron
and see what happens.
It's rare, you only get into the
patient's brain when they
have a neurosurgical procedure
and they're considering a
resection, or removal
of tissue.
You can also do recordings
by putting grids on
top of those brains.
And Penfield did famous studies
for patients with
epilepsy, where he would
stimulate and map things that
contributed a lot to our
thinking about the brain.
But that's a rare source of
evidence, as you can imagine.
Another one that's much more
common-- there's one of these
devices down the street
in building 46--
is Transcranial Magnetic
Stimulation, or TMS.
So this is one in which people
are allowed ethically, and
responsibly to give you a
virtual lesion for a few
moments, if you volunteer
to do so.
So they put some sort of
wire, there's different
configurations, over your head
in a targeted location.
It generates a magnetic field
that passes through the skull
and induces a current.
And what happens is the
current drives lots
of neurons to fire.
Turns out, this is kind of
interesting, if all your
neurons are firing at the same
moment, in one sense it's as
if none of them were, because
there's no information.
There's a lot of different ways
you could think about
that, but for example if on your
300 channel television
you had all the channels on
simultaneously on the same
screen, it wouldn't be
very easy to watch,
something like that.
All the neurons firing pretty
much wipes out the
function of that area.
People do feel a little bit of
a physical sensation, if
you're prone to epilepsy it's
not a good idea to try this,
so it does require some
careful supervision
experimentally.
But you can do this with healthy
people, and if for
example you do it on this side
of the motor cortex, people
twitch or say they felt
somebody touch them.
Nobody touched them, but the
part of the brain that codes
for touch just got turned on.
If you put it on the occipital
cortex, visual cortex, and you
turn on at a certain moment,
you could put a word up and
word down, and the person will
say they saw nothing.
You'll make them functionally,
cortically
blind for a few moments.
People have done experiments
like this to suppress
activity, to enhance activity,
sometimes it makes people even
faster, like naming pictures.
And it's also been used there's
still experimental
studies of whether it can be
helpful for treatments of
neuropsychiatric disorders.
It's not invasive, in a sense of
you're not going literally
inside, you have a causal thing
because turning the
brain on or off.
It's not very well targeted, it
can't go into subcortical
areas, but it's a very
interesting tool.
Let's talk about recording brain
structure for a moment.
It's really important to
separate this concept between
recording structure, which is
a picture of anatomy, or
function, which is a picture
of physiology.
So there's old ones angiography,
and things like
that, I'll show you two.
Computed Tomography, and MR
and a really cool measure
called Diffusion
Tensor Imaging.
And then, dysfunctional
measures, and we'll talk about
those, EEG, PET, fMRI, MEG.
So here's some different
images you can
get from the brain.
This is a post-mortem brain,
this is a cut brain, here's
the front, here's the back.
If a brain was open in
front of you, this is
what you would see.
So here's an MRI, Magnetic
Resonance Imaging, and it's
pretty good, and I'll show you
some more pictures, in showing
you lots of information.
Not as good as if you were in
there, but pretty good.
Here's a CT scan, Computed
Tomography.
It's not as good, it's
more blurry.
And this thing that looks really
sad, it looks like get
your camera to focus, that's
actually the quality of the
picture that we see that
underlies maybe the most
widely used tool these days for
understanding the human
mind and brain, Functional
Magnetic Resonance Imaging.
It's a very smudgy picture,
but it has some really
interesting properties.
So here's the kind of thing you
go into for an MRI, both
structural or functional.
Some of you have almost
certainly been participants in
research or experiments,
or studies, stick up
your hand if you have.
Oh, a lot of you, OK, so you'll
speak up on this, is it
quiet or noisy?
It's super noisy, so you have
to have ear plugs in.
And this is why people doing
experiments with this
Functional MRI want to do
visual studies, because
auditory ones are tricky.
So Tyler, your head TA, likes
auditory stuff, it's 10 times
harder to pull off those
experiments.
Everybody tries to do visual
stuff, so you don't have the
noise problem.
But you get some beautiful
pictures, here's Computed
Tomography.
And here's an MRI structural
scan from the brain, the
ventricles, here's
Basal Ganglia.
With an MRI, beautifully you can
see the difference between
white and gray matter.
I'm always impressed that
the gray matter is
just this thin ribbon.
Cortex really means bark,
it's just like
the bark on our tree.
And when you look at the brain
this way, look at how much
white matter there is.
Here's your frontal cortex, look
at all that white matter
and then this thin, cortical
mantle, or ribbon, or bark.
That's what we think of as the
smarts of language, and social
planning, and things
like that.
So that's a structural
picture.
And then these two pictures
are sort of fun.
This is just recorded down the
street, we're going to fly
through your brain from
one ear to the other.
And you get amazing resolution,
it's not the same
thing like being inside
the brain.
There's things that you don't
see, we know that,
but you see a lot.
Isn't that cool?
Let's examine what
you can see now.
Only about 40 years ago, you
would have to have a person
die to see this.
This is a patient with
Huntington's disease, we'll
come back and talk about
that disorder.
Here's a healthy person,
top of the brain.
This is the caudate here, part
of the Basal Ganglia.
And you could see in a patient
who has passed away that part
of the brain is completely
withered away in
Huntington's disease.
You would have to wait until
person passed away to see
something like that.
Here's a healthy person
top of the brain,
again lining the ventricle.
This is the caudate.
And here in a living
Huntington's patients you can
see the great withering away.
Some of cortex 2 in later
stage of disease, but
especially in the
Basal Ganglia.
Here's a healthy older person,
about 70 years of age, top of
the brain, bottom of the
brain, the ventricle.
Here's on the left and right
of the hippocampus, the
structure we'll talk about,
without which you can cannot
learn any new fact,
or remember any
event in your life.
So powerful for almost every
sense of learning.
And look what happens the
structure in the same aged
patient with Alzheimer's
disease.
It's virtually gone, it's
greatly weathered.
You see it's much wider here,
because the tissue's greatly
shrunk in the Alzheimer's
patient.
So we can see these kinds of
changes in living people, for
both research purposes and
clinical purposes.
Here's one that's more cheerful,
and more reflecting
your experience.
Here are studies of brain
changes from age four to 21.
So they follow a large number
of people at NIH
from age four to 21.
And what this shows is this
color coding is the thickness
of the cortex.
And you might imagine that as
you get older, and smarter and
go through grade school, and
middle school, and high
school, and MIT college, and
as you head towards grad
school, your brain will
get thicker, and
thicker with cortex.
It's exactly the opposite.
Ever since you were about five
years old, you've been
shedding neurons by the
millions, and connections
among them by the trillions.
And you're still going
to do that until your
probably about 22 or 23.
Then you peak, and you decline
and become faculty members.
But that's really interesting,
we'll come back to this, that
what happens as your brain
get smart, experienced,
knowledgeable, all the
differences between you now,
if you're 17, 18, 19, 20, and
when you were four, it all
goes with your cortex
getting thinner.
And we'll come back to that
and how people think about
that, but let's see if I can
get this next movie to run.
There's also an ordering-- and
we'll come back this but I
want to show you this movie.
So the more blue you are, the
thinner you are, the more
advanced you are in terms
of ultimate young adult
development.
Here's visual cortex,
vision coming in.
This is Somatomotor Cortex, how
you feel, your body, and
how you move yourself.
And what you see is, as you go
from age four to 21, the blue
spreads, that spreading is your
brain maturing in higher
thought areas.
So we're going to review your
life on average right now,
here you go.
And now you're ready
to graduate.
It's kind of an amazing story
of fantastic brain changes
that move you from what you
could do and not do at four,
to what you can do and
not do at age 21.
And we couldn't see these
things, we couldn't begin to
see these things, until just
a few years ago in any
scientific sense.
All these things are like
miraculous sources of
information.
So let's pick another
thing, and we'll tie
it to school work.
Here's the structure we
said, the hippocampus.
So important for the formation
of new memories on an everyday
basis, everything that's
important and that you learn.
So here's a fun study they
took, and as you hear it,
think about its scientific
limitation, but it's fun as
students to think about.
They looked at students in
medical school in Germany.
They looked at the measure of
an anatomic thickness of the
hippocampus before and after
they studied like crazy for a
huge exam over some
number of periods.
This is the difference between
the two, and what they're
showing you is that as you
study, your hippocampus got
thicker as you crammed
for your test.
So will there be a day where
instead of having to give you
tests we could just measure
the thickness of your
hippocampus to know how much
you studied, and you could
just zoom in and out of a
scanner, I don't know.
But one cool thing about it is
it's showing you that we can
see structural changes not just
on a giant scale from
when you're four to 21, but from
some number of months of
experience, we can see a
physical change in your brain.
Now that's trivial for animal
researchers, they can show
amazing things in seconds, but
you see the human brain
physically changing.
So let's take a look at another
one, slightly more
controlled, we'll look
at two more examples.
London taxi cab drivers.
If you've travelled in various
cities, and have gone in
various taxis, you may have
had better or worse
experiences whether the taxi
driver knows where he or she
is going exactly.
London is famous for having a
very high code, taxi drivers
have to take big exams to get
their official taxi license,
they create a very
demanding thing.
And when they ask this in the
hippocampus if you learn lots
of routes, if you know tons of
routes in London, what happens
to the hippocampus as
it's memorizing all
these special routes?
And what they saw, that taxi
drivers had bigger hippocampi,
and the longer they drove,
the bigger it was.
So is this a causal or
correlational source of evidence?
It's correlational right?
So let's start with this, they
have bigger hippocampi, and
now maybe that's simply
because, what?
Maybe somebody who has an
awesome hippocampus is ready
to go to be a taxi driver.
Maybe they pass the test, and
the one who got lost all the
time, and was driving to the
wrong airport and stuff, small
hippocampus, never became
a taxi driver.
So the size of the hippocampus
is the cause of your success,
not the consequence.
Because the longer you drove,
the bigger it got, that kind
of goes with that.
But you could do a causal
experiment this way.
They taught people to juggle
three balls, they practiced
every day for three months.
Three months juggling
every day.
What you see in yellow are parts
of the brain-- that's a
statistical map--
parts of the brain that
significantly got thicker in
three months of practice.
So they could compare directly
before and after, it's a
causal experiment.
And these are areas that are
involved in the visual motion,
and it makes sense that areas
involved in visual motion
would somehow change.
But the fact that we can see
three months of experience
change the structure of your
brain, it's kind of remarkable
in they way that we can measure
and scientifically
scrutinize.
You might be curious if you did
three months of this and
you were a pretty good juggler,
you're impressing
your friends at parties, your
brain scan is different.
What do you think happened--
they followed these people
up-- after the juggling
requirements stopped?
They kind of stop, most of the
people, they were too busy.
They would show off here and
there, but that was it.
They measured their brain's
again about six months later,
and this change was gone.
It came in, and it went out
with the activity, it's
activity dependent.
So depending on what you do,
you could think about every
activity you do-- mental and
physical that you do-- is
constantly slightly changing
your brain.
And if you do a lot of it,
you're fundamentally changing
it like in these individuals.
But if you stop doing it you
go right back to where you
were, because you're going to
be doing something else.
And another fun measure that's
kind of beautiful and
intriguing is Diffusion
Tensor Imaging.
Now every [INAUDIBLE] we talked
about so far has been
gray matter of the brain,
the neurons and then the
circuits they form.
We're going to turn to white
matter, which is the
myelinated axons that are
the super conducting
highways of the brain.
And what Diffusion Tensor
Imaging does, it shows you
something about the organization
of that white
matter, measuring directly the
movement of water at very,
very tiny distances.
This is a cross-section of
a myelinated nerve fiber.
Those are the fibers that are
covered with white matter that
have to go some distance.
And the myelin protects the
quality and speed of that
signal through your brain.
And you could see at the level
of, if you're a tiny, tiny
drop of water, or smaller than
that, this is a pretty big
bump in the road.
So imagine you're a little drop
of water moving a little
bit, and you bump up against the
myelin, you go oh, can't
go that way, and you go
back this way, and
you go with the flow.
You go parallel with a myelin,
it's hard to cross it at that
microscopic scale.
But we can measure that movement
in areas where it's
highly constrained, and that's
a property of the water.
Here cerebral spinal fluid,
things can go anywhere.
Here's where there's a lot of
white matter, and the water
tends to flow along parallel
with the white matter, just
for physical reasons it
can't cross it over.
And here for example, is a
statistical map comparing this
measure of white matter
organization between adults,
who either in their childhood
had a diagnosis of dyslexia,
reading was difficult for
these individuals.
Or people who typical reading
development, where you learned
to read and wasn't particularly
difficult.
And you can see that in this
area around the Temporal
Parietal Cortex, there's a
significant difference.
But we can do one more thing.
These are reading scores this
way, this is the measure of
the white matter organization
from the
Diffusion Tensor Imaging.
Each of these as an individual
person now.
So the open dots are the people
who had typical reading
development.
The filled dots are the people
who had poor development, and
you can see it's pretty
continuous.
Even in the people with the open
circles who never had a
problem, the better they
read, the more the
organization is here.
So this is not just the
difference between good and
bad readers, it's a difference
between really good readers,
and medium readers, and poor
readers, right, continuous.
So now, cause or effect?
Were those of you who at three,
who had awesome myelin,
were you going, reading's
a snap.
I love this stuff, where's
War and Peace, mom?
Or, were you like the jugglers,
and you were reading
a lot, and you were exercising
this part of the brain, and
altered its physical
structure.
And the answer is
we don't know.
How could we know?
How could we know?
If you were scientists and were
given a pot of money to
do this, how could you know?
Well--
yeah?
AUDIENCE: Track the entire
lives of multiple people.
PROFESSOR: Yeah, do a
longitudinal study and start
like, before people read.
And you could see is
it different then?
Are we born to be big readers,
or by being big readers do we
alter the architecture
our brain.
What's the effort, and what's
the talent, or what's the
predisposition at birth, and
what's the time you put in
creating this part.
We don't know that yet, but we
have a place to look at that.
And then you can create these
kinds of beautiful pictures,
and I'll say a word
about this.
So this is an individual
person's white matter
organization.
So we could take this picture
of you, or anybody you know
who wants to go in a scanner.
And what's color coded here in
blue are fibers that are
running up or down, we can't
tell with the fibers which
direction they're going,
but we can tell other
orientations.
Up and down, left and right in
red, up and down in blue, and
green is front to back.
Pretty cool, huh?
I can tell you that I'll
say a word about this.
Should we do that again?
I like it, but I work
in this area.
This is fantastic, this is an
individual person's white
matter organization.
As information is flowing around
in your mind, here's
the paths that it's flowing
around in as you just do
anything that's interesting
in your feelings
or thoughts or anything.
It's fantastic.
I can tell you that the
algorithms that are used to
create these maps, there's
some debate
about the better ones.
So the last steps of this are
a bit debated, and a bit
depending on how cool you are
as a visual engineer.
But there's a lot of things
that's right about Diffusion
Tensor Imaging, there's
a lot of things that
are right about it.
Function, so most of all we're
interested in structure, not
just for itself, but how is it
makes your mind do the things
you could do.
And when we think about
different functional measures
that are available to
neuroscientists or
psychologists, we often think
in two dimensions, Spatial
Resolution, and Temporal
Resolution.
How precise are we where we are,
and what's the time scale
that we're measuring in,
milliseconds, are we averaging
over many seconds, many hours.
We know mental operations,
roughly speaking, occur at the
millisecond level, or maybe
10 milliseconds.
There's no answer to that, but
we know lots of things happen
that fast in the mind.
So if you look at this here you
can see that, for example,
if you're in animal work,
looking at size, you can get
down to the Synapse
or the Dendrite.
We can't touch that in humans,
we can't touch
that cellular stuff.
And it's not until we get up
to here, which is like big
patches of the brain, that we
can state things about people.
That's why it's always going
to be fundamental in
neuroscience to link the human
work to the animal work,
because we can't get to the
neurons or anything like that
in a person almost ever.
That has to come from animal
work, where you can do
invasive work.
So we have to look at
a pretty big patches
of the human brain.
How about time?
Well, we can get down to
milliseconds in time in the
human brain.
Functional things like PET and
MRI are here and in the order
of multiple seconds, I'll
come back to this.
But you can see all these
things have strengths.
Now you don't always want to be
down to a single synapse,
it's not clear that we would
understand much of the
organization of the brain at
the level of the synapse.
There's things happening in the
synapse, but a thing like
knowledge, or love, or something
like that probably
we can't study at the level
of the synapse.
Effectively, yet.
Bigger units are probably
more interpretable.
So here's a fun one, EEG's,
Electroencephalography.
So they put on your head some
sort of a cap with electrodes,
and they measure changes in
electrical activity that are
being picked up through
the skull.
And you're picking up huge
changes in hundreds of
thousands of neurons, but
you're able to do it
millisecond by millisecond
at the speed of thought.
The same electrical signal for
EEG and ERP, that evoke
response potentials, with EEG
you just watch it over time.
So you can see these different
rhythms that go with a person
in coma, or in deep sleep,
asleep, drowsy, relaxed.
You can see these characteristic
rhythms that
people can measure.
If you do an experiment, you can
time lock these moment by
moment to some stimulus or
task you give the person.
So here we're going to time lock
these, and then you get a
thing like this that says,
here's a response, maybe the
first moment after I see a word,
a second moment after I
see a word or something
like that.
So you can time lock
large electrical
responses in the brain.
And you get some studies like
this, and we'll come back to
this, but here's a fun one
in language for example.
You read a sentence like, It was
his first day at work, OK
that's the baseline condition in
purple, not a particularly
exciting sentence.
Although, your first day at
work is actually pretty
interesting-- but to
read the sentence.
How about this one: He spread
the warm bread with socks.
You go, Socks?
I'm shocked, that makes
no sense at all.
What happens as you read it,
here's in broken blue line,
you go wow, and that's
called the N400.
But that's kind of cool, that's
400 milliseconds after
you saw that word you said, I
get it's socks but it doesn't
make sense.
So you're violating semantics.
And then they have to do
a control experiment.
And a lot of psychology, in a
course like this, we can't
devote enough time to this.
But I can tell you high quality
research in psychology
is high quality thoughtfulness
like in any other field.
You could say, well maybe it's
not the word "socks" that's
bothering you, maybe just
because it's odd, just like a
weirded out signal, it's
a weirded out signal.
So they do this, She put on
her high-heeled shoes, but
they put shoes in big print
that you didn't expect.
So now you're weirded out,
but it makes sense.
So what happens in your
mind, you a very
different response here.
So here the meaning is wrong,
here the size is wrong.
And see you can read a person's
mind in this sense,
millisecond by millisecond as
they understand something like
a sentence.
You can do it with babies,
which is pretty cute, and
incredibly exciting too.
So we can measure to
the milliseconds.
Lots of people can take doing
it, it's relatively
inexpensive.
Why don't we just run
around and do that?
And we do that at MIT, and lots
of places do this too.
Well, Spatial Resolution is
really problematic, we don't
know where in the brain
the signals are
really coming from.
We know where the electrode
is on the head, but that's
picking up a lot of stuff below
it, we don't know where
the brain is coming from.
The way I think about it a
little bit, imagine you went
to a football game, and you
were on the outside of the
stadium, and you heard big
cheering on the side that you
knew was MIT.
You might think something good
happened to MIT, then you hear
big cheering on the side where
CalTech team is sitting, and
there's fans, it'd be
the usual Rose Bowl.
You might figure something good
happened at CalTech, but
you don't really know exactly
what happened, and exactly
where it happened.
So we don't know where the
signals are coming from in a
very precise way.
There's another method that's
sort of very intriguing too,
and we're just installing it
at MIT, and you could be
amongst the first generation
of participants, if you so
choose to be.
This is called
Magnetoencephalography, active
neurons produce small
magnetic fields.
You can use a superconducting
quantum device to measure this
tiny, tiny change to the
magnetic field, they're
secondary to the
neurons firing.
These signals are problematic
to measure because they're
estimated to be 100 million
times smaller than the earth's
magnetic field.
And all these measures we have
in human brain function, all
of them, the signal is terrible
compared to the
noise, it's terrible compared
to the noise.
And MEG might be the worst,
there's a number of places
that installed MEG, and had to
take it out because the local
traffic on the road was too big
relative to the difference
between the earth's magnetic
field in the signal they get.
Signal to noise is terrible in
every noninvasive human brain
measure we have.
But you get something
beautiful.
Now, any mental thought we have
of any interest of any
kind, we pretty much understand
to be the property
not of a single part of the
brain doing its thing, but a
remarkable concert, different
parts of your brain playing or
interacting with one another.
It's a symphony orchestra doing
anything interesting in
the human mind, and MEG can
show that beautifully.
So here's an individual's
structural MRI that's been
inflated, they've sort of blown
it out like a balloon so
it's sort of easy to look at.
And what you're going to see now
from Dale & Halgren in an
MEG measurement millisecond by
millisecond of what your brain
does, roughly speaking, when
you read a single word, OK
here we go.
See, back and forth, back and
forth, and there's all this
interaction feeding forward from
when you see it, feeding
being backward from parts of
your brain that say, I think I
know what it is, let's
double check.
Back and forth, back
and forth.
Let me do it one more time,
because I think
it's just so cool.
Anything interesting that your
brain does is an incredibly
complicated millisecond by
millisecond interaction
between large scale
brain networks.
So here we go again, reading a
single word, arrives in the
back of the brain, front's
thinking about back, front,
back, front, back front.
We read the word.
It's just amazing, and MEG is
one of the better measures for
us to see this time based
way in which your mind
accomplishes things.
The strengths are it has great
temporal resolution,
noninvasive, Spatial Resolution
is it maybe better
than EEG, or perhaps better, not
as good as a fMRI, we'll
come to that.
And it only can measure neurons
in the cortex that are
parallel to the skull, so we
can't see lots of things like
support local structures
like the hippocampus.
So now we're moving to the
measures that you most often
see, but these other ones
all help us a lot.
And they are all derived from
the following things.
Sadly, for PET or fMRI, the most
widely used studies to
understand how your mind works,
we can't interrogate
the neurons to compute your
mind, we can't, they're off
bounds to us.
The other measures you just
saw are based on neurons.
What we have to do is we have to
look for gossipy neighbors,
that is the vasculature that
surrounds and supports the
neurons that compute the mind.
And we know the neurons require
oxygen and glucose,
metabolically to do their
work, the cellular life.
And the brain area's active,
there's increased blood flow,
and increased energy supplies
that come to that.
So it's all the sort of
inference by the secondary
consequence of neurons
doing their business.
So the brain is about 3 and 1/2
pounds, it's about 2% of
your total body mass.
So it has a tenfold, 20% extra
demand of body oxygen, your
brain cries out for oxygen
at every moment.
So 2% of your body, but 20%
of the oxygen demand.
And it's so sensitive that only
10 minutes of loss of
oxygen can often cause
irreversible brain damage,
especially in structures
like the hippocampus.
The first discovery that blood
changes that are going with
brain changes, blood changes
that are the sort of the
echoes, if you will, a secondary
consequence, is low
tech character current
machines.
This is work from Angelo Mosso
in the late 1880's, and he saw
a patient who had a unusual sort
of malformation, so he
had almost no skull here.
And he put on it something that
measured the pressure
there, and he also measured--
and what's shown here in red
is this pressure as a control
thing, that's pretty clever--
pulses of blood in the forearm,
so those are in blue.
That's the control, that's not
just blood everywhere.
And what he did is, the guy's
still sitting there, nothing
happening, and he noticed that
when the church bells rang
nearby, boom, this device picked
up increased pressure
over this part of the head.
That's pretty cool, it has to
be blood, it's not neurons,
OK, it's blood.
But now he has the signature of
mental life in your brain,
the blood consequence
of a thought, which
is I hear the Church.
They asked the guy, does it have
to be something that you
hear, he says, did you
make your prayers
today, your Ave Maria?
Again nothing happening
peripherally, but boom, as he
gives his answer, a change
in blood pressure there.
Or do math problem, boom,
a change there.
So all of the sudden, blood
changes of a part of the brain
become the witness to that part
of the brain supporting
the mental operations
to do that task.
And here's a PET study, the
first weighted Positron
Emission Tomography, which is
basically used to measure
local brain activity by looking
at the consequences of
photons disintegrating as
they're measured in this sort
of a device.
And here's the way they use this
task to discover which
parts to map the neural
organization
of the human mind.
So I need somebody who's willing
to do a task at their
seat, and it's just going to be
reading words, or coming up
with words.
OK, thanks.
Here you go, ready?
Look at that, in our field we
call that fixation, you're
just looking, OK,
just looking.
Alright, good job.
Ready for something else?
Alright, now just look
at these things,
OK, you see the words?
The technical word is reading.
Alright, now imagine we did one
more thing with you-- and
actually if you were
in a PET scanner
here's what would happen.
If in a PET scanner, you'd be
sitting down there like that,
there'd be a physician in their
lab coat like this.
There'd be physicist in the
basement making up some sort
of a tracer they're going
to inject into you
every round of this.
Because that's what they need to
sort of track this, and it
comes up an elevator, and people
take turns running down
the hall with it, because it has
a pretty short half-life.
The shortness of its half-life
is what makes you able to do
these multiple measures.
This is a pretty big deal
process, and in fact the one
or two PET sessions I ever
attended, you would rotate who
would run down the field with
the radioactive substance, so
you would share the radioactive
substance.
So now you've done that, and
you feel like, I'm doing
pretty good.
So now they come and
they say, are you
ready for another injection?
They have a catheter running
into your arm, and they inject
you again, here comes the
radioactive stuff, the oxygen.
And now they ask you to read the
words aloud presented one
at a time, why don't you
just read aloud one
at a time, go ahead.
AUDIENCE: Rose, cat,
apple, pen, plane.
PROFESSOR: OK, and they say
thank you very much, and we're
going to do one more injection
if that's OK with you, of
radioactive substance.
And now we're going to ask you
to do one thing, and this is
harder, as you see each word
tell us a verb that describes
what you might do with that
object, or what a person might
do, so go ahead, for
rose tell us.
AUDIENCE: Smell, pet,
eat, write, fly.
PROFESSOR: Perfect.
Yeah, I can tell you that in the
experiment they present a
lot of these, and a lot of
subjects after while just go
use, use, use, use, hold,
hold, hold, hold.
But you did a good job, OK.
This is just looking at
something, this is looking at
a word, which is reading.
Now don't forget, we're the only
species that ever read,
reading has been around in our
culture only for about 700
years on any scale, and reading
is an incredible thing
to work correctly.
And you saw the whole brain
flicker to get it right.
But now you're going to say
the word in the next
condition, so you're not just
looking at the word, but
you're also saying it.
And now finally you're not only
saying a word and looking
at it, but you are thinking
about it to come up with
smell, or pet.
So they say, what we're going
to do is we're going to do a
hierarchy of your mind, just
looking, reading, reading and
talking, reading and talking
and thinking.
And by comparing those different
conditions, we'll
subtract them against each
other, and pull out the part
of your mind that sees a word,
that speaks a word, and that
thinks about a word,
and we'll separate
those out in the brain.
So basically the subtraction
method.
So when we compare looking at
fixation versus looking at
words, we'll see what part of
your brain discovers that it's
a word, knows how to read words,
looking at words versus
repeating them.
We'll discover the basis of
speech, speaking a word versus
coming up with the verb,
thinking about stuff, their
meaning, and coming
up with an answer.
So again the idea is if you're
saying something like pet for
the cat, you're doing
all these things.
Or you might just be reading
it aloud, and
we'll subtract them.
In both these conditions, here
you saw a word and read it,
here you saw a word and came
up and produced a verb, you
subtract these two and
you end up with a
statistical image like this.
This is not a raw image of
blood, all these you ever see
those are statistics of the
areas that differed by some
statistical criterion between
one condition and another.
They're all statistics, they're
not blood, or raw
blood, that underlies it, but
what you see is a statistic,
and here's the statistic.
Now in both of these cases,
you saw the word.
In this case you simply read it,
in this case you read it
in your head and you came
up with a verb.
But why don't we see
anything back here?
Why don't we see the seeing of
the word, even though the
seeing occurred in
those conditions?
Why isn't it visible in
this brain picture?
Because it's been
subtracted out.
So always in these brain imaging
experiments, for
reasons I'm about to tell you,
we almost always have to do
some kind of subtraction.
And I'll tell you why, but that
subtraction is very big.
Because what you subtract out,
that's the heart of the
experiment, and your decision
about what's a legitimate
subtraction.
And the reason we have to
do it is this, look
at these two things.
Here's one condition, and here's
the other condition.
Do you see that they look
pretty similar?
Again, signal to noise.
Your brain is busy all the time,
now we ask you to do
something and see
the difference.
And the difference is very tiny
by the way we measure it.
It's not tiny mentally, it's
not tiny in terms of the
consequences for civilization
in the world.
It's tiny because of the weird
way we have to measure it.
I can tell you that if I've
put on an optimal
checkerboard, the
psychophysicists have said,
this turns on your
visual cortex.
I'll get about a 3% to 5% change
in your brain signal.
If you wave your arm, I can get
3% to 5% signal change in
your cortex here.
If I ask you to do everything
in between seeing something
and moving your lips or hand,
everything about thought,
emotion, memory, desire,
motivation, everything that's
big in our life will get
something like that one tenth
of 1% of the signal change.
One tenth of 1% of the
signal change.
Yeah, Tyler's like yeah, that
means you have to test a lot
of subjects, and work 40
years on your Ph.D.
So we have to do that
subtraction, because if we
just take a picture of what's
going on in your head, it's so
much that we can't tell what's
going on at all.
And if we have you do something
that's pretty big,
like seeing like a really
provocative picture, we'll
just get one tenth of 1%
of the signal change.
So we have to do the subtraction
to have a hint.
And then we do one other weird
thing, we don't have to but we
often do it.
We want to average people to
make some general statement
about humanity, as far as we can
do it, based on the 10 MIT
students we test.
So we scrunch everybody's
brain into common space,
everybody's brain's a little
bit different, like their
bodies are a little
bit different.
We scrunch everybody to line
them all up so we have a
common physical space.
So by the time you see this
picture, it's a statistic on
an average of people in
most cases, but you
get an amazing story.
Which up until these
pictures--
about the late 1980s, it was
unimaginable that you could go
inside a living person's brain,
and see what it is that
allows you to hear a word in
auditory cortex, to see a word
in visual cortex, to move your
mouth to speak, or to think,
what's the verb that goes
with that word?
Unimaginable at your--
OK, now I have to do the quick
math, but you'll help me out--
what year were you born in?
'82?
'92?
I know, at my age it
all blends. '92?
OK, so just a year or two before
you were born-- this
was 5 years before you were--
unimaginable that you could
see such a picture.
When I was a graduate student at
Harvard, and the people at
Washington St. Louis
University--
who did the first of these--
did an incredible service
to the field.
Here we saw, oh my gosh, it was
like landing on the moon.
Going inside the human brain,
and knowing which part of the
brain endows us with
human capacities.
Now, we can be appreciative
or we can be skeptical
scientists, and we can say this,
let's pick this one.
Let's compare seeing a
word like "board,"
versus seeing a fixation.
We do that subtraction, and
that's seeing a word.
Just by common sense, what's
wrong with this comparison?
It's OK it's not terrible.
How can you control it better?
To understand what this part of
the brain is really doing?
I heard something?
Well partly it's a meaningful
word, versus something that
doesn't mean anything
to a plus.
But what else could you say
is different between them?
Yeah?
[INAUDIBLE]
GUEST SPEAKER: [INAUDIBLE]
PROFESSOR: In this case, oh my
gosh, yes, and I'll come back
to that, but let me not do
that one for the moment,
because that's a giant story
which I can't fit in today.
Yes your mind can be
all over the place.
So that's definitely the case,
so that's a good one.
Yeah?
GUEST SPEAKER: You could replace
the plus, which is
like really small,
with [INAUDIBLE]
PROFESSOR: Yeah, that's perfect,
OK that's the way I
was going-- the other one's
great too, two great comments.
Yeah you could say like, maybe
this is a part of your brain
it goes with five things,
or something this
big versus this big.
No you go, that's not so
interesting, the part of your
brain that looks at something
this big, versus this big.
But that's just as legitimate
a conclusion here.
How about this, five different
things, versus only this.
There's a lot of different ways
in which you could say,
what is the mental operation
that I've discovered in the
human brain and mind, it all
comes down to the comparison.
So here's what they did to
try to do a better job.
They showed you a more
complicated thing that doesn't
mean anything.
A bunch of letters that you
can't pronounce, a bunch of
letters that you can pronounce,
but it's not a real
word, and here's the
real world itself.
So if you want to say, what do
you think this part of the
mind is doing?
What part the mind does this
part of the brain allow to
happen in humans, and only
humans on this planet?
And every word you ever read
only happens because this part
of the brain does
what it does.
What is that part of
the brain doing?
Is it just simply responding
too complicated
things, five of them?
No, not much, a little
bit, but not much.
How about letters, letters are
pretty interesting, but there
can't be a word by English,
you can't pronounce this.
Not too interested?
A word, a set of letters you've
never seen together
before, but you can pronounce
by the rules of English.
Boom.
That's what I do, says this
part of the brain,
that's what I do.
I say, I see something, and it's
possibly a word and I can
say it by the rules
of English.
And by the way, if it's
a word I've done
before, I do that too.
I'm pretty flexible, I can do
new words, I can do words I've
known before.
It matches what you see with
language, that's reading.
Only our species can take our
visual system, and the
language you learn as a child,
and put them together, and
allow our civilization
to read.
And this is a part of the brain
where those roads meet.
And by the way, we talked about
local and global, the
forest and the trees.
And consistent with what we
talked about the split brain
patients, looking at global
stuff right hemisphere, if
you're looking at local stuff,
left hemisphere.
So we like it when the
information we have from
split-brain patients, or stroke
patients aligns with
healthy people doing a task
as they typically do.
Because then we sort of believe
there's something
right about that.
So PET, pretty good spatial
resolution, I mean, depends
what you mean by good.
My neuroscience colleagues
dismiss everything we ever do
as sort of pathetically
imprecise.
But 5 to 10 millimeters,
not as good as fMRI.
The temporal resolution is very
poor we can only take one
picture that lasts about
a minute, and averages
everything across that.
You have to inject people with
radioactive stuff, and it's
correlational.
But it has one other thing
that's really, really
interesting, Positron
Emission Tomography.
Because you're injecting a
radioactive label, you can
create different kinds of labels
that go to different
parts of the brain.
So here's Parkinson's disease,
which involves damage the
Substantia nigra, and
the Basal Ganglia.
Here's a healthy persons
Substantia nigra, and here's a
person with Parkinson's disease,
where these cells
have died away.
Typically, at least 80% of these
have to die before a
person shows Parkinson's disease
symptoms clinically.
Here's an injection of
radioactive stuff using PET
that binds to Dopamine
receiving neurons.
And you can see that in the
living Parkinson's patient,
this tremendous reduction
in these
receptors waiting for Dopamine.
In a living patient
specifically Dopamine receptors.
So that's a disease.
Here's why video games are
taking over the world.
Oh no, not yet.
We can do one more thing.
We can track the disease from a
typical person, to a person
with moderate Parkinson's
disease or severe.
Within the disease, we
can see differences.
But here's why video games are
taking over the world, because
if we take a healthy person,
young adults, give them this
kind of Dopamine binding tracer,
and have them play a
video game, two things happen.
A, the parts of your brain that
are involved in reward,
Dopamine, is the strongest
to reward
neurotransmitter that we know.
Things go crazy, and what this
graph is showing you is the
better you do, the more
rewarded you are.
This is why you will go for the
next level, because to get
that dopamine fix, you
got to keep going.
And we think these reward
mechanisms underlie
everything, in many ways they
relate to everything.
Why do you do whatever you do,
because at some level, in some
way, you find it rewarding.
And the data is very compelling
that way.
The last method I'll talk about
is functional MRI, and
it's the one that's most
widely visible.
So you sit in a scanner, stimula
are presented to you
to perform a task.
We do a lot of stuff in our
lab with children, we show
them how the frog would do it.
For those of you who've done a
functional MRI experiment,
because there were so many
hands that were put up.
Do any of you want to say a
word about your experience
doing that?
What was it like, easy,
huge fun, recommend,
no, not so much fun.
It will vary a little bit.
We said noisy.
Some people find it
claustrophobic.
GUEST SPEAKER: I dont know, I
didn't really do anything.
I just had to sit there for a
really long time and not move.
PROFESSOR: Oh, so they didn't
ask you to do a task, maybe.
GUEST SPEAKER: Well, for
a big part of it, I
was watching a movie.
PROFESSOR: So for the student
they were watching a movie not
doing anything,
GUEST SPEAKER: [INAUDIBLE]
PROFESSOR: You were doing
yes or no clicks.
So that would be typical
functional MRI kind of
experiment, some of them are
more obnoxious, some are less,
some are funny, some
are not as funny.
Any other experiences?
Was it comfortable, not so
comfortable, medium.
Anybody else want to share?
No, OK.
OK.
So how does this work?
Functional MRI takes advantage
of MRI but it focuses on
hemoglobin, the stuff that
carries oxygen in your blood.
And it rests on the fact that
after oxygen has been
extracted it's more sensitive
to the magnetic field than
oxygenated hemoglobin.
So it's like this.
Here's basically capillaries and
veins, arteries and veins.
And as you go through the
capillary bed, the smallest
vessels, neurons are extracting
oxygen to support
their physical life.
What happens when this part of
the brain gets active, is that
more oxygen is extracted to
support the active neurons.
So we call this BOLD effect,
blood oxygen level dependent.
So we're measuring the change in
blood, changes the ratio of
oxygenated to deoxygenated
hemoglobins, that changes the
magnetic field as
we measure it.
And that's what we directly
measure, not the neurons.
So if the neurons are using up
oxygen, why does the BOLD
signal increase, why does
this ratio go up?
Because intuitively you'd
think it would go down,
because oxygen is being
extracted at a higher rate.
If you look at oxygen being
extracted, right after
something happens, 10
seconds, there's an
initial dip of oxygen.
That's the neurons extracting
oxygen to replenish themselves
from their activity, their
activity has been to give your
mind its life.
Then what happens is there's
this vast oversupply for much
longer time.
Intuitively, it's as if we
said it's so important to
metabolically support the
neurons that make up our
minds, that if some areas
demanding a lot of blood, we
send over way too much extra
as soon as we can, from a
distance to make sure
everything's OK.
And because our measurement is
so sad, we almost can never
measure this initial dip.
We almost always measure the
sustained oversupply of oxygen
to that part of the brain.
So you could say it's such
a house of cards.
The oversupply of the blood
going to a part of the brain
changes the balance of
oxygenated to deoxygenated
hemoglobin that changes
the magnetic property.
And that's how we try to figure
out what that part of
the brain is doing
for your mind.
But it works pretty well
in some cases.
Decent Spatial Resolution, no
injection, you can zoom in a
scanner and do a lot of
different things.
Modest Temporal Resolution,
because it's not milliseconds,
it's always on the order of
seconds, that's correlational,
not causal.
But you get some amazing
results, I'm just going to
present to you two or three.
So here's one, a thing we're
very interested about humans
is empathy.
How much we understand and feel
other people's happiness,
or sadness, or pain.
So the "observation or
imagination of another person
in a particular emotional state
automatically activates
a representation of that state
in the observer," empathy.
And how do we understand how
another person feels, and we
think that's a big thing
in how we relate to
one another as humans.
So Tania Singer did the
following experiment, we
talked about this
before a little
bit, embodied cognition.
That we understand others out
there by the feelings
we know within us.
We don't know their feelings,
but we know our
feelings inside us.
So here's what she did, she
brought in pairs of people who
were friends, or romantic
partners.
And she either had them get
some pain, it was a shock,
within ethical boundaries, but
not pleasant, that's the pain.
Or, you got to watch through a
video camera, while you're
being imaged, your partner
getting the shock.
So think about somebody you
care about and think about
them getting something painful,
and how you would
feel at that moment.
And they asked in the brain,
what's similar and dissimilar,
and we'll focus on what's
similar right now, between
feeling pain yourself, and
observing pain in somebody you
care about, emphasizing with the
pain you see them having.
And what they found is two
areas, something of an
Anterior Cingulate, and
something in the Insula, which
we talked about before, where
there was a lot of overlap.
So this phrase, I'm feeling your
pain, in your brain when
you feel for somebody else's
pain in this physical sense,
you turn on some of the same
brain areas as when you feel
physical pain directly.
It's as if the basis to imagine
another person's
feelings is the feelings you
know so well yourself.
And this is literally shown
now by the brain imaging.
It could've been a story, a
metaphor, an argument, this is
scientific evidence that
supports that likelihood.
So we're going to expend it
in a slightly fun way.
There's been a lot of study in
neuroeconomics thinking about
how we think about, for example,
things like trust.
So one game, and there's a
number of them, is called the
ultimatum game.
And many people probably
know this, but let me
remind you of this.
This version of it has
two players, a
proposer, and a responder.
And what they do is they give
to proposer a certain amount
of money, and the proposer is
allowed to make an offer to
the responder.
If the responder says, No,
nobody gets any money.
Usually people offered about
50%, so let's make this
concrete just for a moment.
Can I pick you for a second?
You can decline.
Imagine if Tyler came over to
me and give me $10, and I
said, how would you feel if I
gave you five and I kept five.
What do you think?
Might you go for It?
GUEST SPEAKER: Yeah, sure.
PROFESSOR: I mean, you go, I'm
$5 dollars ahead, you're $5
ahead, Tyler won't eat this
month because graduate student
stipends are modest, but it's
a zero sum game in the end.
So now Tyler comes over hands
me 10 more dollars, and I
offer you one.
What's your first feeling
assuming that I wasn't your
teacher grading you?
He saw me get ten,
I say here's one.
What's your feeling?
Think about it just for--
GUEST SPEAKER: You'd feel
kind of cheated.
PROFESSOR: --yeah.
You don't have to, by purely
economic perspective, would
you be ahead by taking
that dollar?
Yeah.
A dollar's a dollar, $2
is $2, but people
have a sense of fairness.
Even to their own detriment,
if you offer $2 and lower.
Even knowing that you're just
ruining $1 or two you would've
gotten for nothing, except
saying yes, people half the
time will say no.
It's like, you are so unfair--
you were saying to me, I would
never say this to you-- you
are so unfair, that we're going
to take us both down,
rather than you have the
pleasure of the $8.
OK It's so unfair,
that my sense
of fairness is disturbed.
It's an interesting way to
think about it, imagine a
friend of yours is handed $10,
and they offer you half, and
if you say no, nobody
gets anything, so
it's a trust game.
They had the people in the
scanner playing this game with
two people they saw on
a video monitor.
The two people they're playing
with are set up.
The person in the scanner is
the real participant, the
people out there they see,
are confederates,
they're play actors.
And one is a fair person, here's
$5, thank you, here's
$5, thank you.
Here's $6, oh, you're awesome,
we can get along, And then
there's an unfair player,
here's $1.
And you go, why is
this guy a jerk?
How about $2?
And after a while, you go the
fair player was very decent,
this unfair player--
who you believe is part of the
experiment, but is a set up--
and you're just thinking, why
is this person such a jerk?
They're constantly getting $10,
and constantly giving me
one or two.
No, no, no thank you.
Now, you get a shock, and you
see these two strangers, one
of whom was a wonderful, fair
player, and one of whom was an
absurdly unfair player.
You see them get a shock.
And they had both men and women
in the scanner watching
these things happen.
And here's what happened,
and it's kind of
funny, but you know.
For the women they had overlap
again between the parts of the
brain to turn on in here in the
insula, when they got a
shock, and when either the fair
player got a shock, or
the unfair player.
They felt bad for both
by this measure.
Look at the men in the study.
I feel bad if the fair guy gets
it, but this part of the
brain's like, yeah, give
it to 'em, can
you push up the voltage?
It just came out this way,
whether it would work that way
under all circumstances, all
ages, all societies, other
groups of men and women,
don't know.
But in this sample in
the United Kingdom,
the men had no empathy.
It's worse than that, it's
worse than they had no
empathy, let me show you this.
If they asked to indicate their
desire for revenge against--
this is a behavioral response--
their desire for
revenge against the
bad player.
I don't think they pursued the
unfair player down the street,
but just that feeling.
And the women said, a little
bit, the men said yes, if only
I could take down this person,
that would be great.
And here's the amazing thing,
we'll come back to the
structure called a nucleus
accumbens.
It sits in the bottom of
the Basal Ganglia.
It's the structure that in the
human brain is most identified
with reward and pleasure, most
identified with reward and
pleasure by fMRI imaging.
Look at the nucleus
accumbens when the
unfair player gets zapped.
The women, nothing much, the
men boom, big reward.
Revenge is rewarding
in their brain.
No sympathy, and lots of revenge
satisfaction for the
unfair player.
Now you can decide on your own
life who this applies to or
not, but it's sort
of fun to explore
these different things.
How we form ideas about empathy,
trust, whether they
are in a society
we grow up in.
Somewhat different on average
men and women, huge ranges
within men huge ranges
within women.
So it's a sort of fun
thing to explore.
Let me end with something that's
much more difficult and
disturbing, but another place
where imaging is giving us
insights that you could not
imagined having some time ago.
So this is a very difficult
case, I don't know if any of
you gone through it, I don't
wish it for you.
Some of you probably have, and
many of you will at sometime
in your life, when you have to
make an end of life decision.
And amongst the most famous of
these cases was Terry Schiavo.
Now I don't know that name even
rings a bell for you, but
it got very, very famous amongst
these kinds of cases.
So she had a cardiac arrest,
she had took a lot of diet
pills, and that may
have contributed.
In February 25, 1990, she went
into a coma, and then a
vegetative state.
So a vegetative state is when
a person seems to be kind of
awake, but when you talk with
them, they're not very aware,
they're not responsive, they're
not noticing, they're
not talking.
But their eyes are open, and
they're awake, their eyes are
not closed, so that's
what she is.
And they put in her a feeding
tube, because without that she
wouldn't live, she couldn't
eat and feed herself.
It was a heartbreaking
difference of opinion between
her husband and her parents.
Her husband petitioned some
years later, actually eight
years later, to remove
the feeding tube and
let her pass away.
The parents opposed that, they
said that's not her wishes,
she would want to keep on going
with the feeding tube.
The husband said no, I don't
believe that's her wishes.
So you have this very tragic
confrontation between the
parents who loved her, and the
husband who presumably loved
her having different ideas about
what to do with her,
whether to end her
life or not.
So finally her tube was removed,
but then the parents
went to court, and a judge
reversed it, and they
put the tube back.
She became, sadly, kind of
back and forth, living
nonliving, on judicial
decisions.
Her case became particularly
famous, for a bunch of
reasons, and it went back and
forth from court, to court.
Moving up in the state courts,
and there were several US
Supreme Court decisions about
whether to remove the tube, or
keep the tube in.
And it's a tragic thing, it's
a tragic choice between the
parents and the husband.
It got to the US Congress,
in the US Senate.
President Bush signed a bill
to keep her alive.
Everybody got involved, with
various opinions, finally the
Supreme Court made a series
of decisions.
It was disconnected in
2005, and she died in
March 31 of that year.
So tragic difficult decision,
and a tragic family situation
that became kind
of a political,
and judicial football.
So what's going on in the mind
of somebody like this, and how
could we even begin to interpret
it for a person who
can't speak for themselves
and can't respond.
So let me tell you about
a different case, we
don't know her case.
So, again a vegetative state is
one where you appear to be
awake, but there's no
sign of awareness.
Eyes are open, but the person's
not talking or
responding to anything
in their environment.
So here's a different woman, 23
years old, in 2005 she had
a road traffic accident, severe
traumatic brain injury.
Five months later she's
un-responsive, but she has
preserved sleep-wake, like
she's waking up going to
sleep, waking up
going to sleep.
Eyes open, but un-responsive
in every other way.
They put her into an fMRI
scanner, as well as healthy
comparison people, and
they have them do to
mental imagery tasks.
they read instructions to her.
But you go into scanner, and
you're told to imagine two
different things.
Playing tennis, so imagine in
your mind's eye you playing
tennis for a moment,
imagine that.
Or imagine visiting all the
rooms of your house starting
with your front door, in the
house that you are living in
now, or where you grew up.
Imagine those two things
in your mind.
First of all, just a pure
cognitive neuroscience level,
and we'll come back to that,
imagination is a really
interesting thing.
And it turns out when we imagine
things, again we use
the parts of our brain that
does them, imagination is
perception run backwards.
We can see imagination
in the human brain.
And depending on what you're
imagining, you use the same
systems that you see with.
If you imagine something you're
looking at, it will
turn on your visual system,
it's even more
specific than that.
So let's first look at what
happens with the controls.
When they imagine they're
playing tennis, they turn on
the supplementary motor area,
that's a part of your brain
that plans your physical
movements.
You're not moving, but you're
thinking about it, this is
imagination of movement.
When you plan a movement.,
you turn that on.
When you go around your house,
you turn on spatial areas that
are in the parahippocampal
cortex, and similar areas,
parietal cortex, and
parahippocampal cortex.
They're turned on if we show
you a movie where you're
moving around in spaces.
If you see spaces, you turn
those on, if you imagine
spaces, you turn them on.
So imagination in the brain is
perception run backwards, or
physical action run backwards,
you're not actually doing it.
But look at this patient who
got in the scanner, who was
non responsive, you read her the
instructions, and see what
she does, and look
at her brain.
Asked to imagine tennis,
asked to imagine the
rooms in her house.
It looks just like that.
What does that mean, just
in a common sense,
what does that mean?
Did she understand the
instruction, at some level
yes, she wouldn't turn on those
parts of the brain if
she didn't understand the
instruction, she imagines the
thing you ask her to instruct.
So this guy on the front page
of the New York Times said
fMRI could tell you the internal
mental life of a
person could no longer
speak, or communicate
with any other way.
Now it's turned out since then,
that when they put in
other patients into the scanner,
most of them don't
show this pattern.
So it's not that every patient
in a vegetative state this is
full of mental life
like this person.
And a deeper way, we don't
really understand what this
mental life is like.
We don't know whether she
simply understands some
things, but doesn't have
feelings, or plans, or
desires, or whether
she has those too.
We don't understand really the
full range of mental life, but
we know that she can understand
an instruction, and
her brain follows
through with it.
Most patients, it turns out,
don't look like that in
vegetative states.
So again, brain imaging has
taken us inside the mind of
somebody who cannot communicate
for themselves and
let us say something about
what it is that's
going on in that mind.
In conclusion, we've talked
about different ways of
learning about the brain,
different methods to record
structure and function that
vary in their temporal and
spatial acuity.
And incredibly different ways in
which we can understand the
organization in time and space
of how the brain supports the
human mind.
