NOVA scienceNOW : 1 - Mirror Neurons

ROBERT KRULWICH: Hello again. Gaze into a
mirror, and what do you see? Well, I see my

face, of course. But in my face I see moods,
I see shifts of feeling.

We humans are really good at reading faces
and bodies. 'Cause if I can look at you and

feel what you're feeling, I can learn from
you, connect to you, I can love you. Empathy

is one of our finer traits, and when it happens
it happens so easily, perhaps becauseóand

this is brand new science, this is just out
of the labówe may have some special circuitry

in our brains that helps us whenever we look
at each other.

Ask yourself, "Why do people get so involved,
so deeply, deeply involved, with such anguish,

such pain, such nail biting tension over football?"

COMMENTATOR: The Cleveland Browns are gambling
on defense.

ROBERT KRULWICH: Why are we such suckers for
sports? And it's not just sports. We can lose

it completely at the movies, at video games,
watching a dance. Is there something about

humans, humans particularly, that allows us
to connect so deeply when we watch other peopleówatch

them moving, watch them playing, watch their
faces?

Well, as it happens, scientists have an explanation
for this strange ability to connect. It's

new.

DANIEL GLASER: It had never been found on
a cellular level before.

ROBERT KRULWICH: A set of brain cells, found
on either side of the head, among all the

billions of long branching cells in our brain,
these so-called "mirror neurons," have surprising

power.

DANIEL GLASER: What we've found is the mechanism
that underlies something which is absolutely

fundamental to the way that we see other people
in the world.

ROBERT KRULWICH: And it began entirely by
accident, at a laboratory in the lovely old

city of Parma, Italy, where a group of brain
researchers was working with monkeys, and

they were testing a neuronóthat's a brain
cellóthat always fired...made this sound...

(NEURON FIRING): Clack, clack, clack.

ROBERT KRULWICH: ...whenever the monkey would
grab for a peanut. So the lab had all these

peanuts around, and whenever the monkey made
its move...

(NEURON FIRING): Clack, clack, clack.

ROBERT KRULWICH: ...the neuron would fire.

Scientists thought, "Now here's a neuron that's
essential to motion. It's a motor neuron."

Then, one day, the monkey was just sitting
around, not moving at all, just sitting, when

a human scientist came into the lab. And when
that scientist grasped the peanut? Yeah, the

monkey's cell fired.

Now, the monkey hadn't moved, it was the human
that had moved, suggesting that this neuron

up here couldn't tell the difference between
seeing something and doing somethingóseeing

and doing were the sameóor more intriguingly,
that for this neuron, watching somebody do

something is just like doing it yourself.

The head of the lab, Giacomo Rizzolatti, thought,
"Wow!"

GIACOMO RIZZOLATTI (University of Parma):
The same neurons, one neuron, fired, both

when the monkey observed something, and when
the monkey is doing something. It is almost

unbelievable.

DANIEL GLASER: It was surprising, because
this cell, which was involved with motor planning

for the monkey, turned out to be interested
in the movements of other people as well.

ROBERT KRULWICH: Some people call them "monkey
see, monkey do" neurons, but the name that

stuck is "mirror neurons," because with them,
the brain seems to mirror the movements it

sees.

This accidental discovery got scientists thinking,
doing more tests, and soon it came pretty

clear that this is not just a monkey thing,
it's a people thing, too.

We all know that humans learn by looking and
copying; that's what infants do.

First you look...

MOTHER: One, two, three, four.

ROBERT KRULWICH: ...then you do.

DONNA: Ready? Let's see your feet this way.

ROBERT KRULWICH: And once you've watched and
copied and learned a set of moves, you not

only have them in your head, if you see somebody
else doing it you can share the experience.

They know the moves, you know the moves, so
you can move with them.

DANIEL GLASER: If you can use the years of
training that you, yourself, have doneólearning

to crawl, then learning to walk, then learning
to eatóthis is an incredibly rich set of

knowledge that you could apply to the problem
of actually seeing what's going on.

ROBERT KRULWICH: So that's why, when I head
down the street carrying all these packages,

not only do people watch, look how they're
watching.

They feel my predicament because they know
what it's like to carry heavy packages. They

know all about "carrying." So as they watch
me moving they can feel themselves moving.

Their neurons are "mirroring" the action.

These neurons may be the brain's way of translating
what we see so we can relate to the world.

DANIEL GLASER: The mirror system is the way
that you tap into...the way that you harness

your own abilities and project them out into
the world.

ROBERT KRULWICH: And people are really good
at watching and translating what we see. Like,

with just thirteen moving dotsóthat's all
there are hereóyou'll have no trouble recognizing

these very ordinary activities. What's more,
tests have shown that when a person sees a

movie like this of his own movement, he'll
recognize it immediately as his own.

And that's why sports fans tense with the
action, and wince, and leap. 'Cause if you

know the game...

FOOTBALL FAN 1: Flag! Flag!

FOOTBALL FAN 2: No, no, no flag.

FOOTBALL FAN: No flag.

ROBERT KRULWICH: ...then your neurons are
firing as if it's you playing, giving whole

new meaning to the phrase "armchair quarterback."
That's why it's so easy to be a sports fan.

But there is more, suggests U.C.L.A. professor
Marco Iacoboni. He thinks mirror neurons tie

us, not just to other people's actions, but
to other people's feelings.

MARCO IACOBONI (University of California,
Los Angeles): So the idea was to try to figure

out how the emotional system and this motor
system are connected together.

We're going to go in the scanner and what
you're going to do is to...

ROBERT KRULWICH: To demonstrate, he put me
into this very powerful f.M.R.I. brain scanner

that can peer into the brain while it's working.

And he gave me some goggles so he could show
me pictures when I was in there.

MARCO IACOBONI: So you can see here the eyeball
of Robert.

ROBERT KRULWICH: And once he had a good view
into my brain...

MARCO IACOBONI: Nice looking brain.

ROBERT KRULWICH: Thank you.

MARCO IACOBONI: Robert, you're not supposed
to talk when we scan you, all right?

ROBERT KRULWICH: Sorry.

Then he said, "Okay, I'm going to show you
a bunch of faces. And for each face, I want

you to imitate it."

So I did that. Then he recorded my brain while
I moved my facial muscles.

MARCO IACOBONI: We're going do, right away,
another one.

ROBERT KRULWICH: Okay.

Then he said "Okay, same faces, but this time,
don't move a muscle, just look." So I looked.

When we checked the results...

Oh, there's my brain. I've never seen my brain
before.

MARCO IACOBONI: This is your mirror area.

ROBERT KRULWICH: Iacoboni says that the part
of my brain that's working when I make a face,

the same part gets busy when I see the face.

Plus, when I was looking at these faces, I
remember feeling extra uncomfortable, kind

of bad. But when these faces came on, I felt,
I don't know, I felt better, almost happy.

And, in fact, at that moment I was looking
at the happy face, my brainóand this is my

brain at that instantósee that red area here,
it shows activity in the "happy" emotional

part of my brain.

And when I was imitating "happy" faces, look.
I get an even bigger response.

This, says Iacoboni, is a consistent result.
Mirror neurons, he believes, can send messages

to the limbic, or emotional system in our
brains. So it's possible these neurons help

us tune in to each others' feelings. That's
empathy.

MARCO IACOBONI: We strongly believe that that's
a unifying mechanism that allows people to

actually connect at a very simple level.

ROBERT KRULWICH: You are saying that there's
a place in my brain, which...whose job it

is to live in other people's minds, live in
other people's bodies?

MARCO IACOBONI: That's right.

HELEN HAYES in A FAREWELL TO ARMS: Oh, darling,
I'm going to die! Don't let me die!

GARY COOPER in A FAREWELL TO ARMS: Kat!

ROBERT KRULWICH: And great actors instinctively
know that if they put feeling and drama into

their bodies,...

HELEN HAYES in A FAREWELL TO ARMS: Hold me
tight! Don't let me go!

ROBERT KRULWICH: ...their faces, we will respond.

GARY COOPER in A FAREWELL TO ARMS: You can't
die. You're too brave to die!

DANIEL GLASER: What actors are experts in
is using their movements to inspire feelings

in the people watching. These are the experts
in the mirror system.

V.S. RAMACHANDRAN (University of California,
San Diego): We are intensely social creatures.

We literally read other people's minds. I
don't mean anything psychic like telepathy,

but you can adopt another person's point of
view.

LINDSAY SCHENK (University of California,
San Diego): When you put it together, what

do you think it's going to be?

ROBERT KRULWICH: So if mirror neurons help
us connect emotionally, what about people

who have trouble with this? Kids like Christian,
who has autism?

LINDSAY SCHENK: Why do you like LEGOÆs?

V.S. RAMACHANDRAN: It's been known for some
time that children with autism could be quite

intelligent, but have a profound deficit in
social interaction.

ROBERT KRULWICH: Christian can speak and read
and write, but like many kids with autism,

he will avoid eye contact, he often misunderstands
questions.

LINDSAY SCHENK: So, Christian, can you tell
me what you did in school today?

CHRISTIAN: Doing well.

LINDSAY SCHENK: You're doing well?

CHRISTIAN: Mmhmm.

ROBERT KRULWICH: Everybody wants to know what
exactly causes this. So Dr. Ramachandran and

his graduate student, Lindsay Schenk, designed
an experiment...

LINDSAY SCHENK: So we're going be reading
your brainwaves with this cap.

ROBERT KRULWICH: They recorded brainwaves
while the kids opened and closed their hands

and while they looked at a movie of somebody
else's hands. For most people, the brainwave

looks the same either way, whether they're
doing or seeing. But for the kids with autism,

the wave changes, suggesting, possibly, that
autism might have something to do with broken

mirror neurons.

V.S. RAMACHANDRAN: Their brains may indeed
be different in that regard, and they may

have deficits in their mirror neuron system.
But we don't know this for sure yet. There

needs to be...additional work needs to be
done using brain imaging.

ROBERT KRULWICH: But what we do know, says
Ramachandran, is that healthy human beings

are intensely social. More than our cousins,
the monkeys, we invent ways to connect. We

invent dances, and handshakes, and games to
play. We eat together. We meet and we talk.

We talk a lot.

V.S. RAMACHANDRAN: Everybody's interested
in this question: "What makes humans unique?"

What makes us different from the great apes,
for example? You can say humorówe're the

laughing bipedólanguage certainly, okay?
But another thing is culture. And a lot of

culture comes from imitation, watching your
teachers do something.

ROBERT KRULWICH: And here V.S. Ramachandran
makes a big leap. He has proposed that at

a key moment in our evolution, this is his
guess, our mirror neurons got better. And

that made all the difference, he says, because
once we humans got better at learning from

each otherólooking, copying, teachingówe
could do things the other creatures couldn't.

V.S. RAMACHANDRAN: In other words, if you
are a bear, and suddenly the environment turns

cold, you need a few million years to develop
polar bear type layers of fat and fur.

ROBERT KRULWICH: It would take many, many,
many bear generations to select for furrier

bears. But, says Ramachandran...

V.S. RAMACHANDRAN: If you're a human, you
watch your father slaying another bear and

putting on a fur coat, you know, skinning
it, using that as a coat. You watch it, you

learn it instantly. Your mirror neurons start
firing away in your brain, and you've performed

the same sequence, complicated sequence. Instead
of going through millions of years of evolution,

you've done it in one generation.

ROBERT KRULWICH: And while no one is claiming
that mirror neurons are the key ingredient

that makes us different from other creatures,
what these neurons do suggest about us seems

almost self-evident. You can see it any Sunday
at a sports bar, that deep in our architecture,

down in our cells, we are built to be together.

DANIEL GLASER: There'd be very little point
in having a mirror system if you lived on

your own. There'd be a lot of point in having
a digestive system if you lived on your own.

There'd be a good point in having a movement
system if you lived on your own. There'd be

a good point in having a visual system if
you lived on your own. But there'd be no point

in having a mirror system. The mirror system
is probably the most basic social brain system.

It's a brain system which there's no point
in having if you don't want to interact or

relate to other people.

ROBERT KRULWICH: But we do like to interact.
And maybe now, as never before, we will understand

why. Okay, now, before we leave this subject,
we've designed a little mirror neuron exercise.

What we're going to do is take a wishbone,
an ordinary wishbone, the kind you break for

good luck, and we're going to take itócome
onóand we're going to take it for a stroll.

And, if your mirror neurons are working properly,
when you see anything, even a wishbone walking,

you know, along, you won't just watch that
bone, you are going to be that bone.

The walking bone was created and designed
by artist Arthur Ganson, and later in the

program we will show you a host of Ganson
gadgets in glorious motion.