All language subtitles for NOVA.S50E10.Your.Brain.Whos.in.Control.1080p.WEB.h264-BAE_track3_[eng]

♪ ♪

SUSANA MARTINEZ-CONDE:
The brain is the biggest mystery
in science today.

THALIA WHEATLEY:
It's responsible for all
the facets of our personality,

everything we think
and everything we feel.

It makes you you.

URI MAOZ:
A very large fraction

of what's happening in my brain
I am not aware of at all.

HEATHER BERLIN:
But what exactly is going on
in your unconscious brain?

What part of your brain
is really in charge?

CHARLES LIMB:
All day long, we're doing

unscripted things that we didn't
know we would be doing.

(sizzling)

Life is not scripted.

MAOZ:
Find a word that has
some meaning for you.

BERLIN:
So you might think
you've made a choice...

Representation.

BERLIN:
But in the back of your mind,
you wonder...

Come on!

BERLIN:
Was that really me?

♪ ♪

We might feel
like we're in control.

ANIL SETH:
This idea that we're
in control of our actions

seems critical to
our sense of identity.

BERLIN:
But our brains
may have other ideas.

BOBBY KASTHURI:
The brain is made of
almost 90 billion neurons,

but it produces
this illusion

that there's a single person
inside our skulls.

LUKE CHANG:
For every Pinocchio,
there's always someone

kind of pulling the strings
behind the scenes.

(device beeps)

♪ ♪

MICHAEL GAZZANIGA:
There can be two separated minds
inside one system.

WHEATLEY:
It's not just that motor,

memory, language
is in the brain.

Your personality is up there,

your morality is up there.

BIANCA JONES MARLIN:
We as humans know how
environment and traumatic events

change people.

BERLIN:
"Your Brain: Who's In Control?"

Right now, on "NOVA."

♪ ♪

BERLIN:
Have you ever thought
that you've made

a crystal-clear decision?

(inner voice):
I'm just gonna watch
two episodes tonight.

(narration):
But the next thing you know...

(inner voice):
Okay, just one more episode.

(laugh track playing)

Actually,
it's time to go to bed.

♪ ♪

Well, I bet everyone else has
already finished this season.

(static hissing,
laugh track plays)

Wait, why am I
still watching this?

(narration):
Well, of course,
the answer lies in

your brain.

♪ ♪

Your brain contains multitudes.

It's a complex and intricate
three-pound piece of matter.

But you actually
have no awareness

of most of the things
that are going on

inside your brain.

I'm neuroscientist and clinical
psychologist Heather Berlin.

(laughs)
Come on, man!

BERLIN:
And I'm on a journey to discover

what's really driving
the decisions you make?

(device clicks)

No agency at all.

Who or what
is really in control?

There are important
unconscious processes

in your brain
that you're not aware of.

Most of the time,
the brain is a coordinated,

well-oiled machine,
with different brain regions

working together in harmony.

(audio distorting):
But under certain circumstances,

when things are out of sync,

we can gain deeper insight

into how the
brain actually works.

(wildlife chirping)

♪ ♪

There's one thing
we do every day

with little to no
conscious control.

It's something you might spend a
whole third of your life doing:

sleeping.

When we sleep, we're supposed
to be unconscious and at rest.

But for some people,
that's not always the case.

♪ ♪

(mumbling)

BERLIN:
These are people who sleepwalk.

MAN:
Just like, just like you were?

EMMANUEL DURING:
Sleepwalking is a glitch

in the system,

because our identity is not
in control.

And that's what a lot
of my patients

tell me, like, they,
"I didn't do that.

"That's not possible.

This is not me."

♪ ♪

So, sleepwalking?

Very common condition
or phenomenon.

Simply said,
it's what the word is.

You sleep,

but during your sleep,
you will walk.

We take it for granted, right?

But the walking
is extremely complex.

Just teaching a robot

all the inputs and outputs
for a body

to move forward on two legs
without falling.

All of this,
you don't even think about it.

It works independently.

♪ ♪

BERLIN:
How is it possible to do
complex behaviors like walking,

eating, and sometimes
even driving while sleeping?

♪ ♪

To find out,
I'm visiting a sleep center

at the Icahn School of Medicine
at Mount Sinai.

So, tell me a little bit

about what's happening
with you at night

and your sleepwalking.

Well, I've been
doing some weird things.

I painted a wall
in my living room

and one in my kitchen.

I made a triangle,
a perfect triangle...

What?
...in my kitchen.

So what do you think

when you find that?

Like...
I don't know.

Just-- I laugh,
because I go,

"How the heck I did this?"

BERLIN:
Emmanuel During studies
what's going on in the brain

when someone sleepwalks.

In the center, sleep patients
are wired up with sensors

that pick up
eye and body movements--

as well as their brain waves--
while they sleep.

So what are we
looking at here,

these blue lines?

DURING:
These are the eye movements.

Okay, and then the,
the black lines here?

These are the brain waves.

So this patient is obviously,

he's lying in bed.

Mm-hmm.

And dozes off slowly,
feels sleepy.

And as we move on,
he dives into

deep slow-wave sleep.

BERLIN:
During sleep, your brain

cycles through phases of
high and low activity.

When the brain waves slow down,

scientists call this
"deep sleep."

But when someone sleepwalks...

First of all,
everything looks good.

You see the brainwaves.
Mm-hmm.

Everything is very,
very monotonous,

sort of slow waves.
Mm-hmm.

And then it's interesting,

since there's a buildup of
slow wave,

that the amplitude goes up,

and then suddenly...

Whoa.
So he's seemingly awake.

Sudden.
Yeah.

Looks like a sudden arousal.

Looks sort of scared.
I mean, very brief.

Very fast, eyes open.

There's a,
sort of a split, then.

BERLIN:
The patient looks like
they're awake.

But a couple of key brain
regions seem to stay asleep.

DURING:
There's part of the brain
stays in slow-wave sleep.

It's such a deep stage of, of
sleep, it's hard to wake up,

and the other part of
the brain is already awake.

BERLIN:
One part of the brain
that doesn't wake up during

sleepwalking is called
the prefrontal cortex.

It's the region of the brain
responsible for

deliberate choices and
self-awareness.

DURING:
This prefrontal cortex
is the decision maker.

The other areas of the brain

can mostly work
independently of that.

♪ ♪

So, essentially,
so many parts of the brain

can be engaged without
conscious awareness of it.

BERLIN:
During sleepwalking,
the motor cortex,

which controls movement,
the visual cortex,

which processes
visual information,

and the parts of the brain

that coordinate behaviors
like balance and speech

can all become active

without engaging
the prefrontal cortex.

MAN:
And what exactly are you doing,
ma'am?

It's a special code.

MARTINEZ-CONDE:
Experiences of sleepwalking
reveal that being conscious

is not an all-or-none
situation.

Our unconscious makes a lot of
everyday decisions for us.

NANCY KANWISHER:
For starters, boring stuff,

like regulating your heart rate
and your temperature

and deciding when to take the
food in your stomach

and move it down into your gut.

Like, thank God we don't have to
be aware of all that stuff.

DANIELA SCHILLER:
Motor function,
sensory function,

motor-sensory integration,

memory representation.

All of this is happening

below the surface, like the
inside of a clockwork.

(man mumbling)
BERLIN:
When you sleepwalk,

the brain regions that
control your movement, vision,

and breathing can get up to
all kinds of mischief

without you even knowing it.

But there's one case where even
those regions check out--

during anesthesia.

♪ ♪

We know that there are drugs

that I can give you,
anesthetics,

that would remove
your conscious experience.

SETH:
And we all know that
consciousness comes in degrees.

Like, we can lose consciousness
in sleep,

but then we lose it
in a more profound way

when we are under
general anesthesia.

BERLIN:
When I was a young researcher
working in anesthesiology,

I saw this firsthand.

So what happens to your brain
activity when you go under?

♪ ♪

Neuroscientist Emery Brown
is measuring the line

that separates being conscious

from being unconscious.

BROWN:
I want to guarantee my patients

that when I say
you're unconscious,

you're not going to perceive
pain,

you won't be moving around,

you won't remember
anything that's occurring.

Your heart rate
and blood pressure

and other physiological systems
will be well-controlled.

♪ ♪

BERLIN:
The patient is undergoing
surgery.

But before
the surgeons can operate,

the anesthesiologists
have to put her under--

render her unconscious
with special drugs.

WOMAN:
I'm starting to
give you medicines

that might make
you feel kind of drowsy.

BROWN:
Look straight ahead.

Look straight ahead.

as we expect them to move.

So you're moving her head,
but her eyes stay straight.

WOMAN:
All right, now we're
going to have you breathe

a little oxygen.
BROWN: Breathe some oxygen
for a minute.

And can you
see my finger here?

Follow it with your eyes.

And if you can't follow it
anymore, tell me, all right?

Can you hear me?

♪ ♪

See her eyes are fixed now?
BERLIN: Yeah.

You see the E.E.G. has
a large, slow oscillation?

See that?
BERLIN:
Yeah, yeah.

BROWN:
Her brain stem is out.

BERLIN:
It's out, that's it?
BROWN: Mm-hmm.

BERLIN:
When you go under,
it can feel like

one second you're here,
and the next,

you're out.

What's going on in
the brain when this happens?

Emery uses
a device called an E.E.G.,

a set of electrodes
that rests on the scalp

and detects electrical activity
in the brain.

That activity comes
in the form of waves.

BROWN:
The brain generates
brain waves or oscillations.

And there are oscillations

that we typically see
when someone's conscious.

BERLIN:
These brain waves are
measured by their frequency,

how fast
the waves come and go,

and by their amplitude,
how small or big the waves are.

BROWN:
I look at your E.E.G.

When you're awake,

you're going to have
a very rich response.

When I anesthetize you,
it goes away.

And so the difference
between those two states

represents the transition
from being conscious

to the unconscious.

See the oscillations,
see how they're

really big now.
BERLIN:
Yeah.

And before, see, they were
just sort of little...

Yeah, exactly.
Kind of, yeah.

(talking in background)

BERLIN:
When you're awake and
fully aware,

your brain wave activity is
diverse and dynamic.

It looks kind of like
an exciting conversation.

But when anesthesia drugs
hit the brain,

the activity
is dramatically reduced

to dull, slow-rolling
brain waves.

The once dynamic conversation

becomes
an unintelligible hum.

BROWN:
If you alter how

the parts of the brain
communicate sufficiently,

you can make
someone unconscious.

So that's what
the drugs are doing.

They're altering the way

the various parts
of the brain communicate.

BERLIN:
There's one region of the brain
in particular that acts as

a communication hub:
the thalamus.

It's made up of two parts,
each about the size of a walnut,

and sits deep inside your brain.

BROWN:
Thalamus is a
central way station

for all sorts of
information processing.

Auditory information
goes through there,

visual information
goes through there,

pain information
goes through there.

If I could take out

just one brain center
to make you unconscious,

it would probably be
the thalamus,

because
it's such a central actor

in processing
all types of information.

BERLIN:
After a couple of hours
of surgery,

the medical team is tapering
off the anesthesia drugs.

And the E.E.G. reveals the
patient's brain wave activity

becoming more complex
as she wakes up.

ANTHONY:
She's starting to take

some breaths on her own.
BROWN:
Yeah.

ANTHONY:
Open your eyes wide.

And squeeze my hand.

BROWN:
Consciousness is really having
active cognitive processing,

being able to think and act.

ANTHONY:
Surgery's all done, okay?

BROWN:
It's the integration
of that information

which allows us
to start to understand

how consciousness
is actually formed.

♪ ♪

KASTHURI:
Consciousness can obviously

interact with the physical world
like we can.

We can use drugs to remove it.

We go to sleep and
we're not conscious, and yet,

it's tenuous at the same time.

We can't say how any
specific set of neurons

working together
produces consciousness.

REBECCA SAXE:
It's so clear that anesthesia

is some kind of change of
consciousness, right?

The whole brain is there,
the pieces are there,

in a way that makes for
our conscious experience.

(static hissing,
beeps distorting)

And that's
the difference between

being aware
and not being aware.

BERLIN:
So the level of communication

among brain regions
is one difference

between being conscious
and being unconscious.

That means that no
single area of the brain

is responsible
for your consciousness.

It's that communication
that helps make you you.

MAN:
Now, let's remember
that the left hand

is governed from
the right hemisphere.

BERLIN:
For some people,
an entire half of their brain

can't really
communicate with the rest.

These are people who have
undergone split-brain surgery,

and it's as if...

(audio doubled):
They have two minds
in a single brain.

MAN:
Now the question becomes,

what happens when you allow

both hands together to
try to solve the problem?

And what we find out is
that they fight over each other.

One hand knows how to do it
and one hand does not,

and so they more or less
squabble.

The human brain contains
two sides,

the left hemisphere and the
right hemisphere, right?

And they are connected by a big
bundle of fibers.

It's called the corpus callosum.

All the communication
from one side of the brain

to the other has to pass
through this fiber bundle.

BERLIN:
For some people with epilepsy,
a seizure in one hemisphere

can quickly spread to the other
by way of the corpus callosum.

But if that bridge
is surgically severed,

a seizure can no longer cross
to the other side of the brain.

In addition to
treating epilepsy,

these surgeries
have also led

to some astounding research into

how the two hemispheres
function.

MILLER:
With your left hand,
make me the a-okay sign.

(woman laughs)

BERLIN:
To learn more about these
fascinating studies,

I met two pioneers
in the field:

Michael Miller

and Michael Gazzaniga.

Michael Miller asked me

to step into his lab
to do a few simple tests,

just like the ones
he's conducted with patients

after split-brain surgery.

So, Heather,
what you're going to see

are two shapes.

They're going
to come up on the screen.

♪ ♪

You're gonna draw the shape
on the left side of the screen

with your left hand,

and the shape on the right side
of the screen

with your right hand.

And I want you to draw them
as quickly as you can

at the same time.

Okay?
(laughs): Okay.

BERLIN: Piece of cake, right?

(device beeps)

Oh...
MILLER:
Beautiful.

(laughs)

Okay, not sure what you were
drawing over here, but...

(laughs)

(device beeps)

Oh. (chuckles)
(laughing): Okay.

Did I mention I didn't get
that much sleep last night?

(laughs)

BERLIN:
The left side of the brain

controls most of
the right side of the body.

And the right side
of the brain

controls most of the left side
of the body.

(all laughing)

What happened is, I started out
trying to do different things,

and then they just sort of,
like, sync up together.
MILLER: Yeah, yeah.

♪ ♪

(laughs)
Come on, man.

MILLER:
It's perfectly normal.

So, I mean, what's happening
is that the motor commands

in the, in one hemisphere...
Right.

...are interfering
with the motor commands

in the other hemisphere.

BERLIN:
It was basically impossible

for me to force my hands

to draw two different things
at the same time.

But for someone whose
two hemispheres

are disconnected,
there's no interference.

It's almost as if there's
one mind

controlling the left hand,

and a completely different
mind controlling the right hand.

And it isn't just movement

that's split
across the hemispheres.

Only half of your visual field
goes to each side of the brain.

MILLER:
When you're looking
straight ahead,

everything to the
left side of that space

goes only to
the right hemisphere.

And the opposite is true
for the right side of the space.

GAZZANIGA:
The left part of the brain
is where your language

and speech centers are.

That enables you to talk,

enables you to understand
language, and all the rest.

And the right side of your brain

evaluation of visual space.

I'm going to give you a test.

MAN: If you look
right at my nose,

I'm going to hold
up my hands.

You tell me how many fingers
you see, all right?

GAZZANIGA:
How many fingers do you see?

You see two, right?

Why did you see two?

(chuckling):
This one went to
your left hemisphere,

this one went to
your right hemisphere,

way over in the
other side of your brain.

How does your left
hemisphere know about it?

That pathway,
the corpus callosum.

It transfers that information.

Now I'm going
to split your brain,

and I do the same test.

How many fingers do I see?

WOMAN:
Two.

You see anything else?

No.

Okay.

You see one,
you see this one,

because that goes straight to
your left, talking hemisphere.

This one is still going
to your right hemisphere,

which has now been
disconnected from your left.

So your left brain
can't talk about this.

So you now say
you only see one finger,

even though your right brain
is seeing this finger.

It just can't talk about it,

because the highway that
communicates that information

has been cut.

Show me with your right hand
what you see.

Two.
Okay.

Put it down,
relax.

Show me with your left hand
what you see.

One.
Good.

MILLER:
It's the most remarkable thing
to witness.

You know, there's this
whole other entity

in the head that's
controlling the body

and can understand
and remember

and feel and think
all on its own,

completely separate
from the other side.

BERLIN:
The researchers conducted tests

to explore how
a split-brain patient's

two hemispheres
work independently

from one another--

including a now-famous
experiment

of a patient named Joe.

GAZZANIGA:
Look right at the dot.

BERLIN:
By quickly flashing a word

to just the left side of his
visual field...

(device beeps)
GAZZANIGA:
See anything?

BERLIN:
...that word would go
exclusively

to the right half of his brain,

the half that can't talk.

So the only way we're
going to know that it registered

is if he can
write something out, okay?

With his hand that is controlled
by his right hemisphere.

Exactly, his left hand.
The left hand.

GAZZANIGA:
We flash the word "Texas."

GAZZANIGA:
Look right at the dot.

See anything?

There's a flash.
All right.

I didn't see the word.

His right hemisphere
is seeing it.

GAZZANIGA:
We're seeing it,
but the right hemisphere,

at this point in his surgery,

cannot talk.
Right.

GAZZANIGA:
All right, I want you to
draw for me that thing

upside down.

BERLIN:
So he claims to not have
seen anything.

Yeah.
Oh, my God.

(laughs)
Wow.

BERLIN: He was able
to do Texas upside down.
GAZZANIGA: Yeah.

MILLER:
But what's interesting is, he
had no idea what he's drawing.

MILLER:
We know because we saw the word.

JOE (chuckling):
I can't tell what it is.

BERLIN:
Wow.

GAZZANIGA: So then, later on,
I show him the word again

and I ask a different question

about what he saw.

BERLIN:
Once again, they showed
the word "Texas"

to just his right,
non-verbal hemisphere.

So when asked about what he saw,

all his left
hemisphere can say is...

I'm aware of a word,
I just didn't see what it was.

GAZZANIGA (in video):
Draw something that goes
with that.

A symbol of that.

BERLIN:
Oh, wow,

so he draws a cowboy hat.
MILLER:
Yeah, clearly...

Yeah, clearly, his right
hemisphere

knows exactly
what he's drawing.
Wow.

But his left
is still confused,

so he doesn't understand it.
Right.

GAZZANIGA:
What's that?

Cowboy hat.

Cowboy hat?

What was the word?

(whispering):
So amazing.
JOE (in video): Texas.

(laughing):
I can't believe it.

GAZZANIGA:
Did you see "Texas"?
No.

GAZZANIGA:
The split-brain phenomenon
suggests that there can be

two separated minds,
if you will,

inside of a skull.

The cooperation is on the paper,
not inside the head.

It's an astounding example

of cross-cueing and management
of two mental systems

into one unified act.

And the idea is

maybe that's going on in us
all the time, too.

KANWISHER:
Each of us has a sense
that we're a unitary being,

but actually,
that belies the fact

that each of us,
each of our minds,

is actually composed of
lots of different pieces

that are doing different things.

And different information
can be represented

in different
parts of that machinery.

And so a search for
"where am I in all of this?"

is a little bit misguided,

because the "I" is not

such a unitary thing in the
first place.

KASTHURI:
That feeling of unity, of "me,"
is actually distributed

across almost
90 billion neurons.

This illusion that there's a
single person

inside our skulls.

♪ ♪

BERLIN:
Inside your brain are
over 100 distinct regions.

Many different
systems in the brain

control what you do,
from movement,

to vision, to speech, and
even social interaction.

MAHZARIN BANAJI:
I think most human
beings like to believe

that their mind is
under their own control.

If I want to,
I can stand up right now.

I can do that.

that everything I do
has been chosen by me.

And if there is a story
from the brain to tell,

it is that we are quite wrong.

BERLIN:
Not only are there
multiple parts

of your brain
influencing you,

but there are things
in the world around you

that influence your brain,

including other people.

SAXE:
How we act and who we are
in our lives

is hugely determined by

the expectations of
the people around us.

The brain helps us be the most
social species on the planet.

SCHILLER:
Our brain doesn't
operate in isolation.

We constantly learn, take,
compare to other brains.

CHANG:
Our brains have evolved
to be able to

effortlessly reason about
other people.

And emotions,
similarly, have evolved

as ways that guide our behavior.

and the emotions of others--
influence our brains?

Neuroscientist
Luke Chang studies how

emotions like greed and guilt
affect our decision-making.

MAN:
Hey, Grace, we're going to
start up the scout.

GRACE (on speaker):
Okay.

Go ahead
and make your decision.

(softly):
Okay, did you tell her to
go on to the next one?

MAN:
Yep, you can hit next.

BERLIN:
So, what are you guys
looking at here?

What's this study about?
Is there...

So she's playing
an investment game...

Okay.
...with another
participant,

who's outside the scanner.

BERLIN:
Luke scans the brains
of study participants

while they play a game
from behavioral economics

called the Trust Game.

CHANG:
This is a cooperative game

where one person
has some sum of money,

and they can choose to
invest any amount of that money

in their partner.

BERLIN:
That investment grows.

So then, the study participant
has to decide:

they could be greedy
and keep all the money

or they could be generous,

and give some of
the investment back.

♪ ♪

CHANG:
We've always been
really interested in,

why do people return the money
when they don't have to?

And guilt provides
one plausible mechanism

that might be
driving their behavior

to act cooperatively
in this game.

BERLIN:
And so you're balancing
making these decisions

between getting that
kind of dopamine reward hit

from being a little selfish

versus being balanced by
those feelings of, maybe, guilt

when you're not cooperating
or helping somebody else out.

BERLIN:
And the brain scans
reveal which parts of the brain

are most active when
someone is feeling guilt.

CHANG:
Those regions ended up being

something called the insula.

Signals about having
this gut feeling

that maybe this isn't
a good idea,

or, "I'd feel really bad if
I did that."

Those are the signals that
originate from the insula

that allow us to make decisions
to avoid harming someone else.

♪ ♪

BERLIN:
Luke likes to think of it kind
of like a thermometer

and a thermostat.

CHANG:
If you try to think about how

a thermostat might be mapped
onto the brain,

one region might
be more like the thermometer,

detecting the ambient
temperature in the room.

BERLIN:
When it comes
to reading the room,

our brain's thermometer
seems to be the insula.

But all that information
needs to go somewhere else

and be integrated with
other types of information.

BERLIN:
That's our brain's thermostat--

a region located
inside the prefrontal cortex

that processes our emotions and
helps regulate our behavior.

And while your thermostat can
usually help you

take control of your emotions,

what would happen if it went
out?

♪ ♪

CHANG:
There's a famous
patient named Phineas Gage.

WHEATLEY:
Phineas Gage was a railroad
foreman

who was working in Vermont,

and he was tamping down
a hole that had gunpowder in it,

and the gunpowder ignited,

sending the rod through his eye,
up through his brain,

taking out a big patch
of his brain in the process.

At first people thought,
well, this is a miracle.

This man has been
unscathed from this accident.

He had memory, he had language,
he had motor control.

But of course, his friends
noticed a difference.

CHANG:
His life fell apart-- he had
a hard time holding a job,

he lost all of his friends,
and he really just struggled.

WHEATLEY:
His personality
made him more fitful,

irreverent, more profane.

He was cursing a lot,
lewd behavior.

So he had sort of no filter.

We now know that the parts
of the brain

that he sort of surgically
excised

were involved in emotion
and control.

BERLIN:
Over a hundred years later,

neuroscientists mapped
the regions of his brain

that were harmed
in that horrific accident.

Areas of his prefrontal
cortex,

including the brain's
thermostat, were damaged,

which might account for
why he struggled socially.

He couldn't regulate his
emotions

or process how other people
might react to his behavior.

WHEATLEY:
And that was the key moment, I
think, in neuroscience history

when people realized,

oh, it's not just that motor,
memory,

language is in the brain.

Your personality is up there,
your morality is up there,

things that make you you
are there.

BERLIN:
I think we all kind of know
intuitively that emotions

impact our decisions.

So what sort of extra
information is this giving us?

CHANG:
In a lot of the scientific work

that's been done on studying
emotion in decision making,

people have really focused on

how emotions lead us to make
worse decisions,

maybe even irrational.

And I actually
don't think that's true.

If you have a goal
to not want to harm others

and to do what's going
to be in your self-interest,

emotions are actually helping
us make better decisions.

♪ ♪

WHEATLEY:
We are, in fact,
the company that we keep,

because other people
bring out parts of us,

and strengthen
us in particular ways.

SCHILLER:
How you make decisions,

how you behave,
how you think about yourself,

all of these processes
we develop

by mimicking and interacting

and synchronizing with other
brains.

SAXE:
One thing that we all share
as humans

is that social life and social
contact

is an incredibly important part
of what our brain processes.

Our brains are, in detail,
influenced

by every experience we have.

Every moment, every sentence,
every image

changes your brain.

BERLIN:
And certain
experiences are so profound,

so extreme, that they can impact
brain biology

from one generation to the next.

Neuroscientist Bianca
Jones Marlin is studying

how your ancestors'
experiences might control

how your brain is wired today.

MARLIN:
We ask how trauma affects
the brain,

how trauma affects the body,

and really, how trauma affects
generations.

People in the world
suffer from traumatic events,

and these traumatic events
aren't just

a one-time change in
their brain and their body.

It actually continues
for seemingly their lifetime.

BERLIN:
Bianca's research is
inspired by her upbringing.

MARLIN:
My parents,
my biological parents,

were also foster parents.

So I had foster siblings
and adopted siblings growing up.

Only now as a scientist,
I realize that that motivates

a lot of
the questions that I ask:

how do we understand what
happens when kids

are born into trauma

and optimize what we do have for
better generations?

♪ ♪

BERLIN:
One insight comes from
an event during World War II.

MARLIN:
At the end of World War II,

the Netherlands were
cut off from food by Nazi troops

because they decided
to protest through the country.

And during this period of time,
it created a man-made famine.

There was starvation,
death, there was trauma.

BERLIN:
Not only did those

who suffered during the famine
experience health problems,

but some of their children,
and even their grandchildren,

had metabolic issues.

So people began to ask,
how does an experience

of a parent, of a grandparent,
change offspring?

BERLIN:
Researchers began to discover
that your environment

and your experiences can
change the way your genes

are activated in
your body and in your brain.

MARLIN:
It's not like you get your genes

and it's set in stone.

They're constantly changing
based on the environment.

BERLIN:
To see this in action,

Bianca studies mice.

MARLIN:
We're able to map
the whole genome of mice,

target certain areas

of that genetic code,
and use them

to answer important
questions in science.

BERLIN:
So how could stress and trauma

alter the biology
of the mice's offspring?

To find out,

Bianca paired the smell of
almond

with an electric shock.
(shock buzzes)

MARLIN:
Because mice really navigate
the world

and rely heavily on the sense
of smell,

we use olfaction, pair it with
a light foot shock,

and we observe changes in the
brain and changes in behavior.

BERLIN:
She noticed
that something inside

of the mice's noses changed.

MARLIN:
We're able to look
at the cells in the nose

that only respond to almond.

And what we observe is
that after the light foot shock

and the presentation of almond
coinciding,

there are more cells in the nose

that express the almond
receptor.

It's as if something in
the milieu of the nose says,

almond's important
in this environment.

We need more cells like you.

BERLIN:
Mice grew more cells

that responded
to the smell of almond.

MARLIN:
Each one of these green
dots you see here,

these are neurons.

They're cells that can respond
to the almond smell.

These red dots are
cells that were born

after the presentation
of odor and shock.

And this cell right here,
this red and green cell,

is a cell that was born

after the presentation
of almond and shock

that also responds to almond.

This is the cell
that we want to look at

to see what information
is inside,

because we see more of these

after the odor and shock
pairing.

BERLIN:
Remarkably, these changes were
actually passed down

to the next generation.

MARLIN:
The offspring,
the kids of the parents

that were shocked with odor,

were born with more cells that
express the almond receptor.

Which means there's
a memory that somehow

is maintained in sperm
and egg through implantation

and represented in offspring.

It is as if we are
observing a change in evolution

over the time span of one
generation.

And I just
think that's fascinating.

Because we as humans know how

environment and how traumatic
events change people.

Just being able to take
the science of that

and being able to show that,

we're just justifying what we
already know as humans,

what society has known for a
long time,

what individuals know.

We just want to bring
that to an undeniable truth.

MARTINEZ-CONDE:
Our brains are not static.

We try to make sense of
what's happening right now,

but we also try to make sense of
what happened a long time ago

and to have, like, this grand
picture

of our life as a trajectory.

Our ability
for conscious awareness.

It's a magnificent ability,
this ability

to reflect on our own minds.

But it also leads us astray.

SETH:
I have memories, plans,

I have these feelings
of agency over my actions.

But what the science
itself is telling us is that

these things aren't
necessarily bound together.

Different aspects of
the self can be manipulated,

or even taken away altogether.

BERLIN:
Your biology
and the choices you make

are all molded by your social
interactions

and even your family history.

And yet,
we feel like we have control.

Like we have agency, right?

♪ ♪

MAOZ:
An agent is somebody that is the
author of their own story.

But actually,

most of what's happening in our
brain we are not conscious of.

And I think this gets
you starting to think,

wait a minute, you know,

is really everything under my
control?

BERLIN:
Neuroscientist Uri Maoz

is putting our sense of control
to the test.

We feel like we're in control,

but where exactly does that

feeling come from,
and how does it work?

Ah, here you are.

Hello.
Hello.

Thank you very
much for joining us,

agent-ically
and out of your own volition.

(laughs):
Of course.
Before we start...

Mm-hmm.
...let me give you
this envelope.

Okay.
Please don't
let anybody touch it.

Okay.
And don't look inside,
but we'll need it for later on.

For later, okay.

BERLIN:
To show me how my sense
of control

isn't always what it seems,

Uri kicked things off by trying
to get me

to question my ability to
choose by using a magic trick.

So where would
you like to sit?

Where would I like to sit?

MAOZ: It's really up to you.
BERLIN:
It's really-- I have a choice?

MAOZ:
Wherever you want--
you have a choice.

All right,
so I'm going to sit here.

You're going to sit
over there, okay.
Yes.

So how about just before you sit
down, if you don't mind...

Mm-hmm.

Um, let's see
what this says.

Oh, my God, okay.
So...

So then that one obviously
says the same thing, right?

Um...
No?

Let's check
and see what this one says.

This one says...
Oh, come on.

Okay.
(laughs):
So I'm that predictable?

You don't even know me yet!

BERLIN:
I really don't know how
he did that!

I'm not totally convinced,
but I'm starting to question,

how do I know when
I have made a decision?

If I may,
let me give you,

as a present, a book.

Here you go, this is yours.
Oh, thank you.

And I will just ask
you to leaf through it...

Mm-hmm.
...and find a word that has
some meaning for you.

All right, I got it.

Can you tell
me what the word is?

Representation.

Please write the word down,
representation.
Mm-hmm.

And, you know,
just stick that sticky note

somewhere on that page,
yeah, thank you.
Okay, okay, all right.

BERLIN:
We'll come back to that later.

But for now,
I'm starting to see how choice

and agency aren't
always so straightforward.

So to find out what's
actually going on in the brain

when our sense of
control is in question,

I took a look
at a trial designed

by post-doctoral
researcher Alice Wong.

A volunteer from the lab,
Tomás, is being fitted

with a transcranial magnetic
stimulation device,

TMS for short.

It generates a strong magnetic
field

that can send
signals to your brain.

MAOZ:
The idea is that you

stimulate the brain using
a focused magnetic field.

And if you stimulate
that in the right part

of the motor cortex--
it's a part of the brain

that actually
controls your fingers--

it's like you're
pulling on a string here.

Every time you pull it,
the finger goes.

BERLIN:
With the device hooked up,

the researchers can make
his finger jump

involuntarily by sending
a signal to his motor cortex.

(device clicks)
WONG:
We're going to be locating

the spot of your motor cortex
that moves one of your fingers.

(device clicks)

How about that?
TOMÁS: That works.

That was a pinky movement up.
WONG: Okay.

BERLIN:
Sometimes they ask him
to move his finger on his own.

WONG:
Could you replicate the movement
if in, that you...

TOMÁS:
Was something like this.

BERLIN:
Remarkably, by recording

the small electrical signals
that travel from his brain

down to his finger muscles,

Alice and Uri can pinpoint the
exact moment

that Tomás's brain has initiated
a movement--

almost 50 milliseconds
before he actually moves.

With this information, it's
as though they can predict

his movement slightly
before it actually happens.

So now, his sense of agency
is about to be put to the test.

WONG:
Who initiated the movement?

TOMÁS:
It was me.

WONG:
How much agency did you
feel over the movement?

TOMÁS:
Quite a lot.

Full agency? Okay.

BERLIN:
Normally, the researcher
isn't in the room,

and all the questions
are conducted by the computer.

Who initiated the movement?

I don't know.

How much agency did
you feel over the movement?

TOMÁS:
I would say some agency.

BERLIN:
In some instances,

just as Tomás decides
to move his finger,

the researchers use the magnetic
field to make his finger move.

(device clicks)
WONG:
Who initiated the movement?

I really don't know.

Okay.

How much agency did
you feel over the movement?

A little bit.

BERLIN:
So, even in the instances

when Tomás really did decide
to move his finger...

WONG:
How much agency did you feel

over the movement?
No agency at all.

BERLIN:
...he didn't always
feel like he was in control.

So after the experiment, I was
excited to hear the results.

MAOZ:
When Tomás initiated
the movement himself,

yet we intervened with the TMS,

Tomás said, "That wasn't me,
I didn't initiate the movement.

It was the computer."

He thought that the computer
initiated the movement,

or it was both of them,
or he wasn't sure,

but he almost never
said that it was him.

BERLIN:
So what do you think is going
on there?

How is this happening?

MAOZ:
You know, we walk around
and we feel like, you know,

we are the authors of our,
of our actions and so on.

And you can see with just
a little bit of messing around,

it tends to fall apart.

BERLIN: It's fragile,
like our sense of self...
MAOZ: Yes.

BERLIN:
...our memories,
our sense of agency.

They're all things that
our brain evolved over time.

BERLIN: But they're fragile
and they can be manipulated...
MAOZ: Yes.

BERLIN:
...under the right
circumstances.

MAOZ:
Everything has to align

for you to feel the sense
of agency.

When the finger moves,

we get this feedback
back to the brain

and it's incorporated with
whatever is happening

in the brain
to create the movement.

MAOZ:
And together you get this sense
of agency over the movement.

I think that in everyday life,
we are in control.

However, I think this experiment
shows we're quite happy

to relinquish control.

BERLIN:
Like states of consciousness,

there are levels of agency,

ways it can be manipulated,
and even taken away.

We think A happened and then B
happened.

That's the end of the story.

But of course, most of our brain
activity is unconscious.

That was me.

SETH:
So, we sometimes misinterpret.

Our experience of
voluntary action

is a little bit
retrospective in this sense.

The brain looks at what
the body did,

and figures out if that makes
sense

as an act of its own free will.

♪ ♪

BERLIN:
After the agency experiment,

we had more important
matters to attend to.

So, Heather, when you came in,
I gave you an envelope, right?

Yes.
Nobody touched it but you?

No.

Do you remember
that later on,

I gave you that book?
Mm-hmm.

And in that book,
you opened it

to whatever page you wanted,
and you found a word in there.
Mm-hmm.

Right, where the...
Can you tell
us again what that word was?

Yes, it was on page 105.

And the word was
"representation."

Representation, okay.

So if you don't mind just
putting the book aside

and if you could take the
envelope out now.
Okay.

Can you open it and see
what's inside, please?

Oh, this is one of these things

that's gonna freak me out,
right?
Let's see.

I'm getting chills.

Come on. No way!

Come on-- no, seriously!
(both laugh)

That's really freaky.

So you're in control,
right?

I don't know how you did that--
that is really weird.

I mean, what do I do now?

(laughs):
I don't know where to--
what do I do with that?

BERLIN:
Uri's magic acts are tricks.

Sleights-of-hand
and misdirection.

But when I saw what
was written on the card,

I have to admit I wondered
if my choices mattered at all.

Going to do this...

BERLIN:
Alice Wong's experiment supports

the idea that it isn't just
about what happens in the brain

at the moment
a decision is made.

How did you do that?

BERLIN:
Your sense of agency
or control

also has to do with feedback
you get after the decision--

physical, social, and emotional.

I think of agency as a sense,
so there is a sense of agency

that sometimes
can get disrupted, perhaps,

just like you have a sense
of sight or smell and so on.

Sometimes,
you have visual illusions.

It's similar
with a sense of agency.

I can manipulate
your sense of agency.

But that doesn't
mean that we never

have a sense of agency.

♪ ♪

BERLIN:
Your brain is
a meaning-maker machine.

And creating a sense of agency

is one of the ways it makes
meaning out of your daily life.

BANAJI:
There is no way in
which I can operate

without understanding

what is happening
and why I'm doing it.

It's the filling-in of
the blanks that is necessary

in some ways for survival,
to give meaning, to make sense

of the cause and effect of
things.

KASTHURI:
Perhaps we have
that feeling of consciousness

because it gives
me a sense of agency.

It allows me to pretend like
I'm the one making decisions

and I'm the one
reaping the rewards

or the failures
of that particular decision.

BERLIN:
There are parts of the brain
that allow you

to feel like
the author of your own life.

But that's
only part of the story.

(echoing):
Each of our minds is
actually composed

of lots of different pieces
that are doing different things.

This illusion
that there's a single person

MARLIN:
We know how environment

and how traumatic events change
people.

Our brains are, in detail,
influenced

by the expectations
of the people around us.

But of course, most of our brain
activity is unconscious.

BERLIN:
But there are some situations
where letting go

of conscious control
can have amazing results.

LIMB:
When you're playing the blues,

you have this kind of
well-known musical structure,

this template,
and then you use that

as a launchpad
for improvisation,

for innovation,
and for new ideas.

trying to understand how our
brain operates

when we are being truly
creative.

CHRIS EMDIN:
♪ It's gon' be ill in the MRI ♪

BERLIN:
And today,

he's using a scanner to peer
into the brain

of educator and freestyle
rapper Chris Emdin.

♪ I wonder if I'm going insane
as I'm freestyling, profiling ♪

♪ Still wilin',
it's gon' be ill ♪

You ready for me?
WOMAN: Yes.

LIMB:
Okay, remember,
keep your head still

during the entire thing
and try not to move your feet

or your hands
at all during the rapping.

EMDIN (on speaker):
Okay, doing the best I can.

Yeah, awesome,
thank you.

BERLIN:
First, Charles asks Chris
to perform a memorized piece.

Now, that memory means you're
going to do the memorized lyrics

the way
you originally wrote them.

Okay?
EMDIN: Okay.

LIMB:
Memory.

EMDIN:
♪ I'm a physicist, lyricist,
spitting this ridiculousness ♪

♪ So witness the ignorance
I dismiss ♪
Up a little bit?

♪ Feelings and emotion
is the topic of the course ♪

♪ Staying motionless
to handle balanced force ♪

BERLIN:
Next, he gives him
a prompt and asks him

to improvise-- to create a new,
original piece on the spot.

He doesn't know what's coming.
Mm-hmm.

And that's going
to be his cues for that.

LIMB:
Freestyle: physicist.

EMDIN:
♪ Physicist, lyricist ♪

♪ Emcees like this
will always be kicking this ♪

♪ After all of
that it'll all be over ♪

♪ Lucky like I picked
a four-leaf clover ♪

♪ Can't move my shoulder ♪

♪ 'Cause the MRI machine won't
let me do it ♪

♪ But you wouldn't know
what it is that it's like ♪
(laughs)

♪ I'm like a baseball player
the way I strike ♪

♪ With the raps... ♪
LIMB: Stop.

(chuckles):
He's good.

BERLIN:
So, what does improvisation
or spontaneous creativity

look like in the brain?

LIMB:
What we found was that

the prefrontal cortex
that appears to be linked

to effortful self-monitoring

seemed to be turning off,

deactivating, in a pretty
intense way

in these highly trained
professional musicians

when they start improvising.

So in some sense, by letting go,
by decreasing activation

in the prefrontal cortex,

we can sort of gain control
of our lives in a way.

LIMB:
In fact, if you're
too self-conscious

and you're unable
to relax and let go,

you can't do
something like this.

When you start trying to put
conscious control mechanism,

your performance goes down--
you get worse.

So would you say this
goes to, to any activity,

really, if you're,
for a professional tennis player

or if you're trying
to do a physical activity,

that the more you're
able to practice letting go,

once you've learnt the skill,
the better you'll be.
Exactly.

LIMB:
Free throw shooters that are
able to shoot 99% free throws,

all of a sudden,
when you tell them

you're going to get a million
dollars

if you make the next one...
Mm-hmm.

Then all of a sudden, you inject
conscious control over something

that's much better just to left
to its own subconsciousness.

And then your performance gets
worse,

and you're more likely to choke.

BERLIN:
Surprisingly,
the parts of your brain

that are usually in control
can get in your way.

Your prefrontal cortex,
the decision maker,

can make you overthink something
you've done a thousand times.

LIMB:
Freestyle: stay.

EMDIN:
♪ Yes, you want me to stay ♪

♪ Relaxed,
but I won't never play ♪

LIMB:
Every human being is creative.

Whether they're
creative artistically or not

is another question,
but we're all creative.

We have to be, because
all day long, we're doing

unscripted things that we
didn't know we would be doing.

Life is not scripted.

And so no matter who you are

in this world, you're doing
things that are unplanned.

BERLIN:
All day long,
we're balancing forces

that push us around,
even if we're not aware of them,

from past trauma
to the emotions of others,

and all the hidden
forces affecting your brain.

KASTHURI:
I'd like to believe
that I am in charge of my life,

that I am the agent of my life,

that I actually can control my
emotions,

my abilities, my desires.

And the more I learn
about brains, the more I realize

that this is probably not true.

SETH:
We can be influenced
by our social networks,

by our culture, by our genetics,

by our development,
by our childhood.

(clock ticking)

BERLIN:
Your brain is a complicated
collection

of these intricate parts,

many of which
you have no awareness of,

and they all work together
in a delicate dance

to create your perception
of you.

KANWISHER:
The brain is who you are.

It's really different than
any other organ in that sense.

MARTINEZ-CONDE:
We know that every experience,

every thought, every memory,

every sensation has
its origin in the brain.

KASTHURI:
The brain is made of almost
90 billion neurons,

but it produces the idea

that there's a single thing
inside my head.

My particular
pattern of neuronal connections,

it actually creates me.

And your particular pattern
of neuronal connections

actually creates you.

BERLIN:
Years of studying the brain
have humbled me.

BERLIN:
He looks scared.

BERLIN:
You can't control everything

that makes you who you are.

But the unconscious
you is still you.

BANAJI:
The vast majority

of the brain's work is happening
outside conscious awareness.

(crowd groans)
LIMB: If you try to
over-control some things,

you actually will
decrease your performance.

LIMB:
You have to let go

of conscious self-monitoring
to just kind of, like,

go with the flow.

It could be scary to say
and scary to hear,

but we are not just our own.

WHEATLEY:
We are all multifaceted,
multi-dimensional people.

BERLIN:
And by becoming more aware

of the unconscious processes in
your own brain,

you can become more aware
of what drives you,

and what you ultimately
can control.

♪ ♪

♪ ♪

♪ ♪

♪ ♪

♪ ♪