♪ ♪
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.
See, her eyes move
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,
but the messages
aren't getting through
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
is very important in the
evaluation of emotions,
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
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.
And that gives me, I
think, the false belief
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.
A lot of our brains are devoted
to understanding other people.
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.
BERLIN: So, how
exactly do emotions...
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 w*r II.
MARLIN: At the
end of World w*r II,
the Netherlands were cut
off from food by n*zi 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.
Who initiated the
first movement?
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
inside our skulls.
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.
[playing slow tune]
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.
BERLIN: Charles
Limb is a neuroscientist
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 sh**t 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.
♪ ♪
♪ ♪
♪ ♪
♪ ♪
♪ ♪
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50x10 - Your Brain: Who's in Control?
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Nova often includes interviews with scientists doing research in the subject areas covered and occasionally includes footage of a particular discovery.
Nova often includes interviews with scientists doing research in the subject areas covered and occasionally includes footage of a particular discovery.