00:06 - 00:10
SUSANA MARTINEZ-CONDE:
The brain is the biggest mystery
in science today.
00:10 - 00:14
THALIA WHEATLEY:
It's responsible for all
the facets of our personality,
00:14 - 00:16
everything we think
and everything we feel.
00:16 - 00:18
It makes you you.
00:18 - 00:20
URI MAOZ:
A very large fraction
00:20 - 00:24
of what's happening in my brain
I am not aware of at all.
00:24 - 00:27
HEATHER BERLIN:
But what exactly is going on
in your unconscious brain?
00:27 - 00:30
What part of your brain
is really in charge?
00:30 - 00:32
CHARLES LIMB:
All day long, we're doing
00:32 - 00:34
unscripted things that we didn't
know we would be doing.
00:35 - 00:36
Life is not scripted.
00:37 - 00:40
MAOZ:
Find a word that has
some meaning for you.
00:40 - 00:42
BERLIN:
So you might think
you've made a choice...
00:42 - 00:44
Representation.
00:44 - 00:46
BERLIN:
But in the back of your mind,
you wonder...
00:48 - 00:49
BERLIN:
Was that really me?
00:51 - 00:54
We might feel
like we're in control.
00:54 - 00:56
ANIL SETH:
This idea that we're
in control of our actions
00:56 - 00:58
seems critical to
our sense of identity.
00:59 - 01:02
BERLIN:
But our brains
may have other ideas.
01:02 - 01:05
BOBBY KASTHURI:
The brain is made of
almost 90 billion neurons,
01:05 - 01:07
but it produces
this illusion
01:07 - 01:11
that there's a single person
inside our skulls.
01:11 - 01:13
LUKE CHANG:
For every Pinocchio,
there's always someone
01:13 - 01:15
kind of pulling the strings
behind the scenes.
01:15 - 01:16
(device beeps)
01:18 - 01:22
MICHAEL GAZZANIGA:
There can be two separated minds
inside one system.
01:22 - 01:24
WHEATLEY:
It's not just that motor,
01:24 - 01:26
memory, language
is in the brain.
01:26 - 01:27
Your personality is up there,
01:27 - 01:30
your morality is up there.
01:30 - 01:34
BIANCA JONES MARLIN:
We as humans know how
environment and traumatic events
01:34 - 01:36
change people.
01:36 - 01:39
BERLIN:
"Your Brain: Who's In Control?"
01:39 - 01:42
Right now, on "NOVA."
01:55 - 01:57
BERLIN:
Have you ever thought
that you've made
01:57 - 01:59
a crystal-clear decision?
01:59 - 02:01
(inner voice):
I'm just gonna watch
two episodes tonight.
02:01 - 02:03
(narration):
But the next thing you know...
02:04 - 02:05
(inner voice):
Okay, just one more episode.
02:05 - 02:08
(laugh track playing)
02:08 - 02:09
Actually,
it's time to go to bed.
02:11 - 02:13
Well, I bet everyone else has
already finished this season.
02:13 - 02:14
(static hissing,
laugh track plays)
02:14 - 02:16
Wait, why am I
still watching this?
02:16 - 02:19
(narration):
Well, of course,
the answer lies in
02:22 - 02:25
Your brain contains multitudes.
02:25 - 02:30
It's a complex and intricate
three-pound piece of matter.
02:30 - 02:32
But you actually
have no awareness
02:32 - 02:33
of most of the things
that are going on
02:33 - 02:35
inside your brain.
02:35 - 02:40
I'm neuroscientist and clinical
psychologist Heather Berlin.
02:40 - 02:43
Come on, man!
02:43 - 02:45
BERLIN:
And I'm on a journey to discover
02:46 - 02:48
what's really driving
the decisions you make?
02:48 - 02:49
(device clicks)
02:49 - 02:51
No agency at all.
02:52 - 02:54
Who or what
is really in control?
02:55 - 02:58
There are important
unconscious processes
02:58 - 02:59
in your brain
that you're not aware of.
02:59 - 03:02
Most of the time,
the brain is a coordinated,
03:02 - 03:05
well-oiled machine,
with different brain regions
03:05 - 03:08
working together in harmony.
03:08 - 03:10
(audio distorting):
But under certain circumstances,
03:10 - 03:11
when things are out of sync,
03:11 - 03:13
we can gain deeper insight
03:13 - 03:17
into how the
brain actually works.
03:17 - 03:20
(wildlife chirping)
03:28 - 03:29
There's one thing
we do every day
03:29 - 03:31
with little to no
conscious control.
03:31 - 03:35
It's something you might spend a
whole third of your life doing:
03:36 - 03:41
When we sleep, we're supposed
to be unconscious and at rest.
03:41 - 03:46
But for some people,
that's not always the case.
03:52 - 03:54
BERLIN:
These are people who sleepwalk.
03:54 - 03:56
MAN:
Just like, just like you were?
03:56 - 03:57
EMMANUEL DURING:
Sleepwalking is a glitch
03:57 - 03:59
in the system,
03:59 - 04:01
because our identity is not
in control.
04:01 - 04:05
And that's what a lot
of my patients
04:05 - 04:07
tell me, like, they,
"I didn't do that.
04:07 - 04:10
"That's not possible.
04:10 - 04:11
This is not me."
04:19 - 04:20
So, sleepwalking?
04:20 - 04:22
Very common condition
or phenomenon.
04:22 - 04:24
Simply said,
it's what the word is.
04:26 - 04:29
but during your sleep,
you will walk.
04:29 - 04:31
We take it for granted, right?
04:31 - 04:32
But the walking
is extremely complex.
04:32 - 04:35
Just teaching a robot
04:35 - 04:39
all the inputs and outputs
for a body
04:39 - 04:44
to move forward on two legs
without falling.
04:44 - 04:47
All of this,
you don't even think about it.
04:47 - 04:50
It works independently.
04:52 - 04:55
BERLIN:
How is it possible to do
complex behaviors like walking,
04:55 - 05:00
eating, and sometimes
even driving while sleeping?
05:01 - 05:03
To find out,
I'm visiting a sleep center
05:03 - 05:06
at the Icahn School of Medicine
at Mount Sinai.
05:06 - 05:08
So, tell me a little bit
05:08 - 05:10
about what's happening
with you at night
05:10 - 05:12
and your sleepwalking.
05:12 - 05:14
Well, I've been
doing some weird things.
05:15 - 05:16
I painted a wall
in my living room
05:16 - 05:18
and one in my kitchen.
05:18 - 05:20
I made a triangle,
a perfect triangle...
05:20 - 05:21
...in my kitchen.
05:21 - 05:22
So what do you think
05:22 - 05:23
when you find that?
05:24 - 05:25
I don't know.
05:25 - 05:26
Just-- I laugh,
because I go,
05:26 - 05:28
"How the heck I did this?"
05:29 - 05:32
BERLIN:
Emmanuel During studies
what's going on in the brain
05:32 - 05:33
when someone sleepwalks.
05:33 - 05:36
In the center, sleep patients
are wired up with sensors
05:36 - 05:39
that pick up
eye and body movements--
05:39 - 05:42
as well as their brain waves--
while they sleep.
05:43 - 05:44
So what are we
looking at here,
05:44 - 05:45
these blue lines?
05:45 - 05:47
DURING:
These are the eye movements.
05:47 - 05:49
Okay, and then the,
the black lines here?
05:49 - 05:50
These are the brain waves.
05:50 - 05:51
So this patient is obviously,
05:51 - 05:52
he's lying in bed.
05:54 - 05:57
And dozes off slowly,
feels sleepy.
05:57 - 05:59
And as we move on,
he dives into
05:59 - 06:01
deep slow-wave sleep.
06:01 - 06:03
BERLIN:
During sleep, your brain
06:03 - 06:07
cycles through phases of
high and low activity.
06:07 - 06:09
When the brain waves slow down,
06:09 - 06:11
scientists call this
"deep sleep."
06:11 - 06:14
But when someone sleepwalks...
06:14 - 06:17
First of all,
everything looks good.
06:17 - 06:20
You see the brainwaves.
06:20 - 06:22
Everything is very,
very monotonous,
06:22 - 06:23
sort of slow waves.
06:24 - 06:25
And then it's interesting,
06:25 - 06:27
since there's a buildup of
slow wave,
06:27 - 06:29
that the amplitude goes up,
06:29 - 06:31
and then suddenly...
06:31 - 06:33
So he's seemingly awake.
06:34 - 06:37
Looks like a sudden arousal.
06:37 - 06:39
Looks sort of scared.
06:37 - 06:39
I mean, very brief.
06:39 - 06:40
Very fast, eyes open.
06:40 - 06:43
There's a,
sort of a split, then.
06:43 - 06:46
BERLIN:
The patient looks like
they're awake.
06:46 - 06:50
But a couple of key brain
regions seem to stay asleep.
06:50 - 06:53
DURING:
There's part of the brain
stays in slow-wave sleep.
06:53 - 06:56
It's such a deep stage of, of
sleep, it's hard to wake up,
06:56 - 06:58
and the other part of
the brain is already awake.
06:58 - 07:01
BERLIN:
One part of the brain
that doesn't wake up during
07:01 - 07:04
sleepwalking is called
the prefrontal cortex.
07:04 - 07:06
It's the region of the brain
responsible for
07:06 - 07:09
deliberate choices and
self-awareness.
07:09 - 07:13
DURING:
This prefrontal cortex
is the decision maker.
07:13 - 07:15
The other areas of the brain
07:15 - 07:18
can mostly work
independently of that.
07:20 - 07:22
So, essentially,
so many parts of the brain
07:22 - 07:26
can be engaged without
conscious awareness of it.
07:26 - 07:29
BERLIN:
During sleepwalking,
the motor cortex,
07:29 - 07:32
which controls movement,
the visual cortex,
07:32 - 07:34
which processes
visual information,
07:34 - 07:35
and the parts of the brain
07:35 - 07:38
that coordinate behaviors
like balance and speech
07:38 - 07:39
can all become active
07:39 - 07:42
without engaging
the prefrontal cortex.
07:43 - 07:45
MAN:
And what exactly are you doing,
ma'am?
07:45 - 07:49
It's a special code.
07:49 - 07:53
MARTINEZ-CONDE:
Experiences of sleepwalking
reveal that being conscious
07:53 - 07:56
is not an all-or-none
situation.
07:56 - 08:01
Our unconscious makes a lot of
everyday decisions for us.
08:01 - 08:04
NANCY KANWISHER:
For starters, boring stuff,
08:04 - 08:06
like regulating your heart rate
and your temperature
08:06 - 08:08
and deciding when to take the
food in your stomach
08:08 - 08:10
and move it down into your gut.
08:10 - 08:13
Like, thank God we don't have to
be aware of all that stuff.
08:13 - 08:16
DANIELA SCHILLER:
Motor function,
sensory function,
08:16 - 08:17
motor-sensory integration,
08:17 - 08:19
memory representation.
08:19 - 08:20
All of this is happening
08:20 - 08:25
below the surface, like the
inside of a clockwork.
08:25 - 08:28
(man mumbling)
08:25 - 08:28
BERLIN:
When you sleepwalk,
08:29 - 08:31
the brain regions that
control your movement, vision,
08:31 - 08:34
and breathing can get up to
all kinds of mischief
08:34 - 08:36
without you even knowing it.
08:36 - 08:40
But there's one case where even
those regions check out--
08:40 - 08:42
during anesthesia.
08:44 - 08:45
We know that there are drugs
08:45 - 08:46
that I can give you,
anesthetics,
08:46 - 08:49
that would remove
your conscious experience.
08:50 - 08:53
SETH:
And we all know that
consciousness comes in degrees.
08:53 - 08:55
Like, we can lose consciousness
in sleep,
08:55 - 08:57
but then we lose it
in a more profound way
08:57 - 09:00
when we are under
general anesthesia.
09:01 - 09:04
BERLIN:
When I was a young researcher
working in anesthesiology,
09:04 - 09:06
I saw this firsthand.
09:06 - 09:11
So what happens to your brain
activity when you go under?
09:17 - 09:19
Neuroscientist Emery Brown
is measuring the line
09:19 - 09:21
that separates being conscious
09:21 - 09:24
from being unconscious.
09:24 - 09:26
BROWN:
I want to guarantee my patients
09:26 - 09:27
that when I say
you're unconscious,
09:27 - 09:29
you're not going to perceive
pain,
09:29 - 09:31
you won't be moving around,
09:31 - 09:33
you won't remember
anything that's occurring.
09:33 - 09:35
Your heart rate
and blood pressure
09:35 - 09:36
and other physiological systems
will be well-controlled.
09:41 - 09:44
BERLIN:
The patient is undergoing
surgery.
09:44 - 09:46
But before
the surgeons can operate,
09:46 - 09:48
the anesthesiologists
have to put her under--
09:48 - 09:52
render her unconscious
with special drugs.
09:52 - 09:53
WOMAN:
I'm starting to
give you medicines
09:53 - 09:55
that might make
you feel kind of drowsy.
09:55 - 09:57
BROWN:
Look straight ahead.
09:57 - 09:58
Look straight ahead.
09:58 - 10:00
See, her eyes move
10:00 - 10:01
as we expect them to move.
10:01 - 10:03
So you're moving her head,
but her eyes stay straight.
10:03 - 10:05
WOMAN:
All right, now we're
going to have you breathe
10:05 - 10:07
a little oxygen.
10:05 - 10:07
BROWN: Breathe some oxygen
for a minute.
10:07 - 10:09
And can you
see my finger here?
10:09 - 10:12
Follow it with your eyes.
10:12 - 10:15
And if you can't follow it
anymore, tell me, all right?
10:17 - 10:18
Can you hear me?
10:21 - 10:23
See her eyes are fixed now?
10:21 - 10:23
BERLIN: Yeah.
10:23 - 10:26
You see the E.E.G. has
a large, slow oscillation?
10:26 - 10:27
BERLIN:
Yeah, yeah.
10:27 - 10:29
BROWN:
Her brain stem is out.
10:29 - 10:31
BERLIN:
It's out, that's it?
10:29 - 10:31
BROWN: Mm-hmm.
10:31 - 10:34
BERLIN:
When you go under,
it can feel like
10:34 - 10:36
one second you're here,
and the next,
10:36 - 10:39
you're out.
10:39 - 10:42
What's going on in
the brain when this happens?
10:42 - 10:46
Emery uses
a device called an E.E.G.,
10:47 - 10:49
a set of electrodes
that rests on the scalp
10:49 - 10:52
and detects electrical activity
in the brain.
10:52 - 10:56
That activity comes
in the form of waves.
10:56 - 11:00
BROWN:
The brain generates
brain waves or oscillations.
11:00 - 11:01
And there are oscillations
11:01 - 11:04
that we typically see
when someone's conscious.
11:04 - 11:07
BERLIN:
These brain waves are
measured by their frequency,
11:07 - 11:09
how fast
the waves come and go,
11:09 - 11:13
and by their amplitude,
how small or big the waves are.
11:13 - 11:14
BROWN:
I look at your E.E.G.
11:14 - 11:16
When you're awake,
11:16 - 11:18
you're going to have
a very rich response.
11:18 - 11:21
When I anesthetize you,
it goes away.
11:21 - 11:23
And so the difference
between those two states
11:23 - 11:25
represents the transition
from being conscious
11:25 - 11:27
to the unconscious.
11:27 - 11:28
See the oscillations,
see how they're
11:28 - 11:29
really big now.
11:28 - 11:29
BERLIN:
Yeah.
11:29 - 11:31
And before, see, they were
just sort of little...
11:31 - 11:32
Yeah, exactly.
11:31 - 11:32
Kind of, yeah.
11:32 - 11:35
(talking in background)
11:35 - 11:37
BERLIN:
When you're awake and
fully aware,
11:37 - 11:41
your brain wave activity is
diverse and dynamic.
11:41 - 11:44
It looks kind of like
an exciting conversation.
11:44 - 11:49
But when anesthesia drugs
hit the brain,
11:49 - 11:52
the activity
is dramatically reduced
11:52 - 11:55
to dull, slow-rolling
brain waves.
11:55 - 11:57
The once dynamic conversation
11:57 - 12:00
becomes
an unintelligible hum.
12:00 - 12:01
BROWN:
If you alter how
12:01 - 12:03
the parts of the brain
communicate sufficiently,
12:03 - 12:04
you can make
someone unconscious.
12:04 - 12:07
So that's what
the drugs are doing.
12:07 - 12:08
They're altering the way
12:08 - 12:09
the various parts
of the brain communicate.
12:11 - 12:15
BERLIN:
There's one region of the brain
in particular that acts as
12:15 - 12:18
a communication hub:
the thalamus.
12:18 - 12:21
It's made up of two parts,
each about the size of a walnut,
12:21 - 12:24
and sits deep inside your brain.
12:24 - 12:26
BROWN:
Thalamus is a
central way station
12:26 - 12:28
for all sorts of
information processing.
12:28 - 12:30
Auditory information
goes through there,
12:30 - 12:32
visual information
goes through there,
12:32 - 12:35
pain information
goes through there.
12:35 - 12:36
If I could take out
12:37 - 12:38
just one brain center
to make you unconscious,
12:38 - 12:40
it would probably be
the thalamus,
12:40 - 12:42
because
it's such a central actor
12:42 - 12:44
in processing
all types of information.
12:45 - 12:47
BERLIN:
After a couple of hours
of surgery,
12:47 - 12:51
the medical team is tapering
off the anesthesia drugs.
12:51 - 12:56
And the E.E.G. reveals the
patient's brain wave activity
12:56 - 12:58
becoming more complex
as she wakes up.
12:58 - 13:00
ANTHONY:
She's starting to take
13:00 - 13:01
some breaths on her own.
13:00 - 13:01
BROWN:
Yeah.
13:01 - 13:03
ANTHONY:
Open your eyes wide.
13:03 - 13:05
And squeeze my hand.
13:05 - 13:08
BROWN:
Consciousness is really having
active cognitive processing,
13:09 - 13:10
being able to think and act.
13:10 - 13:12
ANTHONY:
Surgery's all done, okay?
13:12 - 13:13
BROWN:
It's the integration
of that information
13:13 - 13:16
which allows us
to start to understand
13:16 - 13:18
how consciousness
is actually formed.
13:22 - 13:24
KASTHURI:
Consciousness can obviously
13:24 - 13:26
interact with the physical world
like we can.
13:26 - 13:28
We can use drugs to remove it.
13:28 - 13:31
We go to sleep and
we're not conscious, and yet,
13:31 - 13:33
it's tenuous at the same time.
13:33 - 13:36
We can't say how any
specific set of neurons
13:36 - 13:39
working together
produces consciousness.
13:39 - 13:41
REBECCA SAXE:
It's so clear that anesthesia
13:41 - 13:44
is some kind of change of
consciousness, right?
13:44 - 13:48
The whole brain is there,
the pieces are there,
13:48 - 13:50
but the messages
aren't getting through
13:50 - 13:52
in a way that makes for
our conscious experience.
13:52 - 13:53
(static hissing,
beeps distorting)
13:53 - 13:55
And that's
the difference between
13:55 - 13:57
being aware
and not being aware.
13:58 - 14:00
BERLIN:
So the level of communication
14:00 - 14:02
among brain regions
is one difference
14:02 - 14:05
between being conscious
and being unconscious.
14:05 - 14:10
That means that no
single area of the brain
14:10 - 14:13
is responsible
for your consciousness.
14:13 - 14:17
It's that communication
that helps make you you.
14:17 - 14:20
MAN:
Now, let's remember
that the left hand
14:20 - 14:22
is governed from
the right hemisphere.
14:22 - 14:25
BERLIN:
For some people,
an entire half of their brain
14:25 - 14:28
can't really
communicate with the rest.
14:28 - 14:32
These are people who have
undergone split-brain surgery,
14:32 - 14:34
and it's as if...
14:34 - 14:38
(audio doubled):
They have two minds
in a single brain.
14:38 - 14:39
MAN:
Now the question becomes,
14:39 - 14:41
what happens when you allow
14:41 - 14:43
both hands together to
try to solve the problem?
14:43 - 14:45
And what we find out is
that they fight over each other.
14:45 - 14:48
One hand knows how to do it
and one hand does not,
14:48 - 14:51
and so they more or less
squabble.
14:51 - 14:53
The human brain contains
two sides,
14:53 - 14:55
the left hemisphere and the
right hemisphere, right?
14:55 - 14:58
And they are connected by a big
bundle of fibers.
14:58 - 15:00
It's called the corpus callosum.
15:00 - 15:03
All the communication
from one side of the brain
15:03 - 15:07
to the other has to pass
through this fiber bundle.
15:07 - 15:11
BERLIN:
For some people with epilepsy,
a seizure in one hemisphere
15:11 - 15:16
can quickly spread to the other
by way of the corpus callosum.
15:16 - 15:18
But if that bridge
is surgically severed,
15:19 - 15:22
a seizure can no longer cross
to the other side of the brain.
15:23 - 15:25
In addition to
treating epilepsy,
15:25 - 15:27
these surgeries
have also led
15:27 - 15:29
to some astounding research into
15:29 - 15:32
how the two hemispheres
function.
15:32 - 15:35
MILLER:
With your left hand,
make me the a-okay sign.
15:35 - 15:36
(woman laughs)
15:36 - 15:40
BERLIN:
To learn more about these
fascinating studies,
15:40 - 15:42
I met two pioneers
in the field:
15:42 - 15:44
Michael Miller
15:44 - 15:46
and Michael Gazzaniga.
15:46 - 15:49
Michael Miller asked me
15:49 - 15:52
to step into his lab
to do a few simple tests,
15:52 - 15:55
just like the ones
he's conducted with patients
15:55 - 15:56
after split-brain surgery.
15:56 - 15:58
So, Heather,
what you're going to see
15:58 - 15:59
are two shapes.
15:59 - 16:01
They're going
to come up on the screen.
16:03 - 16:05
You're gonna draw the shape
on the left side of the screen
16:05 - 16:06
with your left hand,
16:06 - 16:07
and the shape on the right side
of the screen
16:07 - 16:09
with your right hand.
16:09 - 16:11
And I want you to draw them
as quickly as you can
16:11 - 16:13
at the same time.
16:13 - 16:14
(laughs): Okay.
16:14 - 16:16
BERLIN: Piece of cake, right?
16:16 - 16:18
(device beeps)
16:19 - 16:20
MILLER:
Beautiful.
16:24 - 16:25
Okay, not sure what you were
drawing over here, but...
16:27 - 16:28
(device beeps)
16:29 - 16:31
Oh. (chuckles)
16:29 - 16:31
(laughing): Okay.
16:31 - 16:32
Did I mention I didn't get
that much sleep last night?
16:35 - 16:37
BERLIN:
The left side of the brain
16:37 - 16:39
controls most of
the right side of the body.
16:39 - 16:41
And the right side
of the brain
16:41 - 16:43
controls most of the left side
of the body.
16:45 - 16:46
(all laughing)
16:46 - 16:48
What happened is, I started out
trying to do different things,
16:48 - 16:50
and then they just sort of,
like, sync up together.
16:48 - 16:50
MILLER: Yeah, yeah.
16:52 - 16:53
Come on, man.
16:53 - 16:55
MILLER:
It's perfectly normal.
16:55 - 16:58
So, I mean, what's happening
is that the motor commands
16:58 - 17:00
in the, in one hemisphere...
17:00 - 17:01
...are interfering
with the motor commands
17:01 - 17:03
in the other hemisphere.
17:03 - 17:06
BERLIN:
It was basically impossible
17:06 - 17:07
for me to force my hands
17:07 - 17:10
to draw two different things
at the same time.
17:12 - 17:13
But for someone whose
two hemispheres
17:13 - 17:17
are disconnected,
there's no interference.
17:17 - 17:19
It's almost as if there's
one mind
17:19 - 17:21
controlling the left hand,
17:21 - 17:24
and a completely different
mind controlling the right hand.
17:24 - 17:26
And it isn't just movement
17:26 - 17:28
that's split
across the hemispheres.
17:28 - 17:33
Only half of your visual field
goes to each side of the brain.
17:33 - 17:35
MILLER:
When you're looking
straight ahead,
17:35 - 17:38
everything to the
left side of that space
17:38 - 17:41
goes only to
the right hemisphere.
17:41 - 17:44
And the opposite is true
for the right side of the space.
17:44 - 17:48
GAZZANIGA:
The left part of the brain
is where your language
17:48 - 17:49
and speech centers are.
17:49 - 17:51
That enables you to talk,
17:51 - 17:54
enables you to understand
language, and all the rest.
17:54 - 17:55
And the right side of your brain
17:56 - 17:59
is very important in
the evaluation of emotions,
17:59 - 18:03
evaluation of visual space.
18:03 - 18:05
I'm going to give you a test.
18:05 - 18:07
MAN: If you look
right at my nose,
18:07 - 18:09
I'm going to hold
up my hands.
18:09 - 18:11
You tell me how many fingers
you see, all right?
18:11 - 18:13
GAZZANIGA:
How many fingers do you see?
18:13 - 18:15
You see two, right?
18:15 - 18:17
Why did you see two?
18:17 - 18:21
(chuckling):
This one went to
your left hemisphere,
18:21 - 18:23
this one went to
your right hemisphere,
18:23 - 18:25
way over in the
other side of your brain.
18:25 - 18:27
How does your left
hemisphere know about it?
18:27 - 18:30
That pathway,
the corpus callosum.
18:30 - 18:32
It transfers that information.
18:32 - 18:35
Now I'm going
to split your brain,
18:35 - 18:36
and I do the same test.
18:36 - 18:39
How many fingers do I see?
18:41 - 18:43
You see anything else?
18:48 - 18:50
You see one,
you see this one,
18:50 - 18:54
because that goes straight to
your left, talking hemisphere.
18:54 - 18:57
This one is still going
to your right hemisphere,
18:57 - 19:01
which has now been
disconnected from your left.
19:01 - 19:04
So your left brain
can't talk about this.
19:04 - 19:06
So you now say
you only see one finger,
19:06 - 19:10
even though your right brain
is seeing this finger.
19:10 - 19:13
It just can't talk about it,
19:13 - 19:16
because the highway that
communicates that information
19:16 - 19:17
has been cut.
19:17 - 19:20
Show me with your right hand
what you see.
19:22 - 19:25
Put it down,
relax.
19:25 - 19:28
Show me with your left hand
what you see.
19:31 - 19:34
MILLER:
It's the most remarkable thing
to witness.
19:34 - 19:36
You know, there's this
whole other entity
19:36 - 19:39
in the head that's
controlling the body
19:39 - 19:41
and can understand
and remember
19:41 - 19:43
and feel and think
all on its own,
19:43 - 19:45
completely separate
from the other side.
19:47 - 19:49
BERLIN:
The researchers conducted tests
19:49 - 19:51
to explore how
a split-brain patient's
19:52 - 19:54
two hemispheres
work independently
19:54 - 19:56
from one another--
19:56 - 19:58
including a now-famous
experiment
19:58 - 19:59
of a patient named Joe.
19:59 - 20:02
GAZZANIGA:
Look right at the dot.
20:02 - 20:04
BERLIN:
By quickly flashing a word
20:04 - 20:06
to just the left side of his
visual field...
20:06 - 20:08
(device beeps)
20:06 - 20:08
GAZZANIGA:
See anything?
20:08 - 20:09
BERLIN:
...that word would go
exclusively
20:09 - 20:11
to the right half of his brain,
20:11 - 20:14
the half that can't talk.
20:14 - 20:16
So the only way we're
going to know that it registered
20:16 - 20:19
is if he can
write something out, okay?
20:19 - 20:22
With his hand that is controlled
by his right hemisphere.
20:22 - 20:24
Exactly, his left hand.
20:22 - 20:24
The left hand.
20:24 - 20:26
GAZZANIGA:
We flash the word "Texas."
20:26 - 20:28
GAZZANIGA:
Look right at the dot.
20:28 - 20:29
See anything?
20:29 - 20:31
There's a flash.
20:31 - 20:33
I didn't see the word.
20:33 - 20:36
His right hemisphere
is seeing it.
20:36 - 20:38
GAZZANIGA:
We're seeing it,
but the right hemisphere,
20:38 - 20:41
at this point in his surgery,
20:41 - 20:43
cannot talk.
20:43 - 20:49
GAZZANIGA:
All right, I want you to
draw for me that thing
20:49 - 20:51
upside down.
20:51 - 20:53
BERLIN:
So he claims to not have
seen anything.
20:57 - 21:00
BERLIN: He was able
to do Texas upside down.
20:57 - 21:00
GAZZANIGA: Yeah.
21:00 - 21:02
MILLER:
But what's interesting is, he
had no idea what he's drawing.
21:03 - 21:04
MILLER:
We know because we saw the word.
21:04 - 21:06
JOE (chuckling):
I can't tell what it is.
21:06 - 21:08
BERLIN:
Wow.
21:08 - 21:10
GAZZANIGA: So then, later on,
I show him the word again
21:10 - 21:11
and I ask a different question
21:11 - 21:14
about what he saw.
21:14 - 21:16
BERLIN:
Once again, they showed
the word "Texas"
21:16 - 21:19
to just his right,
non-verbal hemisphere.
21:19 - 21:21
So when asked about what he saw,
21:21 - 21:24
all his left
hemisphere can say is...
21:24 - 21:27
I'm aware of a word,
I just didn't see what it was.
21:27 - 21:30
GAZZANIGA (in video):
Draw something that goes
with that.
21:30 - 21:32
A symbol of that.
21:34 - 21:36
BERLIN:
Oh, wow,
21:36 - 21:37
so he draws a cowboy hat.
21:36 - 21:37
MILLER:
Yeah, clearly...
21:37 - 21:38
Yeah, clearly, his right
hemisphere
21:38 - 21:40
knows exactly
what he's drawing.
21:40 - 21:43
But his left
is still confused,
21:43 - 21:44
so he doesn't understand it.
21:44 - 21:46
GAZZANIGA:
What's that?
21:49 - 21:51
What was the word?
21:51 - 21:52
(whispering):
So amazing.
21:51 - 21:52
JOE (in video): Texas.
21:52 - 21:53
(laughing):
I can't believe it.
21:54 - 21:57
GAZZANIGA:
Did you see "Texas"?
21:57 - 22:01
GAZZANIGA:
The split-brain phenomenon
suggests that there can be
22:01 - 22:03
two separated minds,
if you will,
22:03 - 22:05
inside of a skull.
22:05 - 22:09
The cooperation is on the paper,
not inside the head.
22:09 - 22:11
It's an astounding example
22:11 - 22:15
of cross-cueing and management
of two mental systems
22:15 - 22:16
into one unified act.
22:17 - 22:19
And the idea is
22:19 - 22:22
maybe that's going on in us
all the time, too.
22:24 - 22:27
KANWISHER:
Each of us has a sense
that we're a unitary being,
22:27 - 22:29
but actually,
that belies the fact
22:29 - 22:31
that each of us,
each of our minds,
22:31 - 22:33
is actually composed of
lots of different pieces
22:33 - 22:34
that are doing different things.
22:34 - 22:36
And different information
can be represented
22:36 - 22:39
in different
parts of that machinery.
22:39 - 22:43
And so a search for
"where am I in all of this?"
22:43 - 22:44
is a little bit misguided,
22:44 - 22:46
because the "I" is not
22:46 - 22:48
such a unitary thing in the
first place.
22:48 - 22:53
KASTHURI:
That feeling of unity, of "me,"
is actually distributed
22:53 - 22:56
across almost
90 billion neurons.
22:56 - 23:00
This illusion that there's a
single person
23:00 - 23:01
inside our skulls.
23:03 - 23:07
BERLIN:
Inside your brain are
over 100 distinct regions.
23:07 - 23:09
Many different
systems in the brain
23:09 - 23:11
control what you do,
from movement,
23:11 - 23:15
to vision, to speech, and
even social interaction.
23:17 - 23:19
MAHZARIN BANAJI:
I think most human
beings like to believe
23:19 - 23:22
that their mind is
under their own control.
23:22 - 23:25
If I want to,
I can stand up right now.
23:25 - 23:26
I can do that.
23:26 - 23:30
And that gives me, I think,
the false belief
23:30 - 23:32
that everything I do
has been chosen by me.
23:33 - 23:35
And if there is a story
from the brain to tell,
23:35 - 23:37
it is that we are quite wrong.
23:37 - 23:39
BERLIN:
Not only are there
multiple parts
23:39 - 23:41
of your brain
influencing you,
23:42 - 23:43
but there are things
in the world around you
23:43 - 23:46
that influence your brain,
23:46 - 23:48
including other people.
23:48 - 23:51
SAXE:
How we act and who we are
in our lives
23:51 - 23:54
is hugely determined by
23:54 - 23:56
the expectations of
the people around us.
23:56 - 24:00
The brain helps us be the most
social species on the planet.
24:00 - 24:04
A lot of our brains are devoted
to understanding other people.
24:04 - 24:08
SCHILLER:
Our brain doesn't
operate in isolation.
24:08 - 24:12
We constantly learn, take,
compare to other brains.
24:12 - 24:15
CHANG:
Our brains have evolved
to be able to
24:15 - 24:18
effortlessly reason about
other people.
24:18 - 24:20
And emotions,
similarly, have evolved
24:20 - 24:22
as ways that guide our behavior.
24:22 - 24:26
BERLIN:
So, how exactly do emotions--
24:26 - 24:30
and the emotions of others--
influence our brains?
24:31 - 24:33
Neuroscientist
Luke Chang studies how
24:33 - 24:37
emotions like greed and guilt
affect our decision-making.
24:37 - 24:39
MAN:
Hey, Grace, we're going to
start up the scout.
24:39 - 24:41
GRACE (on speaker):
Okay.
24:41 - 24:43
Go ahead
and make your decision.
24:44 - 24:45
(softly):
Okay, did you tell her to
go on to the next one?
24:45 - 24:46
MAN:
Yep, you can hit next.
24:48 - 24:50
BERLIN:
So, what are you guys
looking at here?
24:50 - 24:52
What's this study about?
Is there...
24:52 - 24:54
So she's playing
an investment game...
24:54 - 24:55
...with another
participant,
24:55 - 24:57
who's outside the scanner.
24:57 - 25:01
BERLIN:
Luke scans the brains
of study participants
25:01 - 25:04
while they play a game
from behavioral economics
25:04 - 25:06
called the Trust Game.
25:07 - 25:08
CHANG:
This is a cooperative game
25:08 - 25:11
where one person
has some sum of money,
25:11 - 25:13
and they can choose to
invest any amount of that money
25:13 - 25:14
in their partner.
25:14 - 25:17
BERLIN:
That investment grows.
25:17 - 25:22
So then, the study participant
has to decide:
25:22 - 25:25
they could be greedy
and keep all the money
25:25 - 25:27
or they could be generous,
25:27 - 25:29
and give some of
the investment back.
25:31 - 25:33
CHANG:
We've always been
really interested in,
25:33 - 25:36
why do people return the money
when they don't have to?
25:36 - 25:39
And guilt provides
one plausible mechanism
25:39 - 25:41
that might be
driving their behavior
25:41 - 25:43
to act cooperatively
in this game.
25:44 - 25:46
BERLIN:
And so you're balancing
making these decisions
25:46 - 25:50
between getting that
kind of dopamine reward hit
25:50 - 25:51
from being a little selfish
25:52 - 25:56
versus being balanced by
those feelings of, maybe, guilt
25:56 - 25:58
when you're not cooperating
or helping somebody else out.
26:00 - 26:03
BERLIN:
And the brain scans
reveal which parts of the brain
26:03 - 26:07
are most active when
someone is feeling guilt.
26:07 - 26:08
CHANG:
Those regions ended up being
26:08 - 26:09
something called the insula.
26:09 - 26:12
Signals about having
this gut feeling
26:12 - 26:14
that maybe this isn't
a good idea,
26:14 - 26:16
or, "I'd feel really bad if
I did that."
26:16 - 26:18
Those are the signals that
originate from the insula
26:18 - 26:21
that allow us to make decisions
to avoid harming someone else.
26:24 - 26:26
BERLIN:
Luke likes to think of it kind
of like a thermometer
26:26 - 26:28
and a thermostat.
26:28 - 26:29
CHANG:
If you try to think about how
26:29 - 26:31
a thermostat might be mapped
onto the brain,
26:31 - 26:34
one region might
be more like the thermometer,
26:34 - 26:37
detecting the ambient
temperature in the room.
26:37 - 26:39
BERLIN:
When it comes
to reading the room,
26:39 - 26:43
our brain's thermometer
seems to be the insula.
26:43 - 26:46
But all that information
needs to go somewhere else
26:46 - 26:48
and be integrated with
other types of information.
26:48 - 26:51
BERLIN:
That's our brain's thermostat--
26:51 - 26:53
a region located
inside the prefrontal cortex
26:53 - 26:58
that processes our emotions and
helps regulate our behavior.
26:58 - 27:00
And while your thermostat can
usually help you
27:00 - 27:02
take control of your emotions,
27:02 - 27:06
what would happen if it went
out?
27:08 - 27:11
CHANG:
There's a famous
patient named Phineas Gage.
27:11 - 27:13
WHEATLEY:
Phineas Gage was a railroad
foreman
27:13 - 27:15
who was working in Vermont,
27:15 - 27:21
and he was tamping down
a hole that had gunpowder in it,
27:21 - 27:22
and the gunpowder ignited,
27:22 - 27:25
sending the rod through his eye,
up through his brain,
27:25 - 27:30
taking out a big patch
of his brain in the process.
27:30 - 27:33
At first people thought,
well, this is a miracle.
27:33 - 27:36
This man has been
unscathed from this accident.
27:36 - 27:41
He had memory, he had language,
he had motor control.
27:41 - 27:43
But of course, his friends
noticed a difference.
27:44 - 27:46
CHANG:
His life fell apart-- he had
a hard time holding a job,
27:46 - 27:52
he lost all of his friends,
and he really just struggled.
27:52 - 27:54
WHEATLEY:
His personality
made him more fitful,
27:54 - 27:56
irreverent, more profane.
27:56 - 27:58
He was cursing a lot,
lewd behavior.
27:58 - 28:00
So he had sort of no filter.
28:00 - 28:02
We now know that the parts
of the brain
28:02 - 28:05
that he sort of surgically
excised
28:05 - 28:09
were involved in emotion
and control.
28:10 - 28:12
BERLIN:
Over a hundred years later,
28:12 - 28:15
neuroscientists mapped
the regions of his brain
28:15 - 28:18
that were harmed
in that horrific accident.
28:18 - 28:20
Areas of his prefrontal
cortex,
28:20 - 28:23
including the brain's
thermostat, were damaged,
28:23 - 28:26
which might account for
why he struggled socially.
28:26 - 28:28
He couldn't regulate his
emotions
28:28 - 28:33
or process how other people
might react to his behavior.
28:33 - 28:37
WHEATLEY:
And that was the key moment, I
think, in neuroscience history
28:37 - 28:39
when people realized,
28:39 - 28:42
oh, it's not just that motor,
memory,
28:42 - 28:44
language is in the brain.
28:44 - 28:46
Your personality is up there,
your morality is up there,
28:46 - 28:50
things that make you you
are there.
28:50 - 28:54
BERLIN:
I think we all kind of know
intuitively that emotions
28:54 - 28:56
impact our decisions.
28:56 - 28:59
So what sort of extra
information is this giving us?
28:59 - 29:01
CHANG:
In a lot of the scientific work
29:01 - 29:03
that's been done on studying
emotion in decision making,
29:03 - 29:05
people have really focused on
29:05 - 29:06
how emotions lead us to make
worse decisions,
29:06 - 29:09
maybe even irrational.
29:09 - 29:11
And I actually
don't think that's true.
29:11 - 29:13
If you have a goal
to not want to harm others
29:13 - 29:16
and to do what's going
to be in your self-interest,
29:16 - 29:19
emotions are actually helping
us make better decisions.
29:21 - 29:23
WHEATLEY:
We are, in fact,
the company that we keep,
29:23 - 29:27
because other people
bring out parts of us,
29:27 - 29:29
and strengthen
us in particular ways.
29:31 - 29:32
SCHILLER:
How you make decisions,
29:32 - 29:35
how you behave,
how you think about yourself,
29:35 - 29:37
all of these processes
we develop
29:37 - 29:39
by mimicking and interacting
29:39 - 29:41
and synchronizing with other
brains.
29:43 - 29:45
SAXE:
One thing that we all share
as humans
29:45 - 29:50
is that social life and social
contact
29:50 - 29:53
is an incredibly important part
of what our brain processes.
29:53 - 29:55
Our brains are, in detail,
influenced
29:55 - 29:57
by every experience we have.
29:57 - 29:59
Every moment, every sentence,
every image
29:59 - 30:03
changes your brain.
30:03 - 30:06
BERLIN:
And certain
experiences are so profound,
30:06 - 30:09
so extreme, that they can impact
brain biology
30:09 - 30:13
from one generation to the next.
30:13 - 30:16
Neuroscientist Bianca
Jones Marlin is studying
30:16 - 30:20
how your ancestors'
experiences might control
30:20 - 30:22
how your brain is wired today.
30:22 - 30:25
MARLIN:
We ask how trauma affects
the brain,
30:25 - 30:27
how trauma affects the body,
30:27 - 30:31
and really, how trauma affects
generations.
30:31 - 30:33
People in the world
suffer from traumatic events,
30:34 - 30:35
and these traumatic events
aren't just
30:35 - 30:38
a one-time change in
their brain and their body.
30:38 - 30:40
It actually continues
for seemingly their lifetime.
30:41 - 30:45
BERLIN:
Bianca's research is
inspired by her upbringing.
30:45 - 30:47
MARLIN:
My parents,
my biological parents,
30:47 - 30:49
were also foster parents.
30:49 - 30:51
So I had foster siblings
and adopted siblings growing up.
30:51 - 30:54
Only now as a scientist,
I realize that that motivates
30:54 - 30:56
a lot of
the questions that I ask:
30:56 - 30:59
how do we understand what
happens when kids
30:59 - 31:01
are born into trauma
31:01 - 31:03
and optimize what we do have for
better generations?
31:06 - 31:10
BERLIN:
One insight comes from
an event during World War II.
31:10 - 31:12
MARLIN:
At the end of World War II,
31:12 - 31:15
the Netherlands were
cut off from food by Nazi troops
31:15 - 31:17
because they decided
to protest through the country.
31:17 - 31:20
And during this period of time,
it created a man-made famine.
31:20 - 31:23
There was starvation,
death, there was trauma.
31:23 - 31:25
BERLIN:
Not only did those
31:25 - 31:28
who suffered during the famine
experience health problems,
31:28 - 31:33
but some of their children,
and even their grandchildren,
31:33 - 31:36
had metabolic issues.
31:36 - 31:38
So people began to ask,
how does an experience
31:38 - 31:42
of a parent, of a grandparent,
change offspring?
31:42 - 31:47
BERLIN:
Researchers began to discover
that your environment
31:47 - 31:50
and your experiences can
change the way your genes
31:50 - 31:53
are activated in
your body and in your brain.
31:53 - 31:55
MARLIN:
It's not like you get your genes
31:56 - 31:57
and it's set in stone.
31:57 - 31:59
They're constantly changing
based on the environment.
31:59 - 32:01
BERLIN:
To see this in action,
32:01 - 32:03
Bianca studies mice.
32:03 - 32:06
MARLIN:
We're able to map
the whole genome of mice,
32:06 - 32:08
target certain areas
32:08 - 32:11
of that genetic code,
and use them
32:11 - 32:13
to answer important
questions in science.
32:13 - 32:16
BERLIN:
So how could stress and trauma
32:16 - 32:19
alter the biology
of the mice's offspring?
32:20 - 32:22
To find out,
32:22 - 32:24
Bianca paired the smell of
almond
32:24 - 32:26
with an electric shock.
32:24 - 32:26
(shock buzzes)
32:26 - 32:29
MARLIN:
Because mice really navigate
the world
32:29 - 32:31
and rely heavily on the sense
of smell,
32:31 - 32:34
we use olfaction, pair it with
a light foot shock,
32:34 - 32:37
and we observe changes in the
brain and changes in behavior.
32:38 - 32:39
BERLIN:
She noticed
that something inside
32:39 - 32:44
of the mice's noses changed.
32:44 - 32:46
MARLIN:
We're able to look
at the cells in the nose
32:46 - 32:47
that only respond to almond.
32:48 - 32:51
And what we observe is
that after the light foot shock
32:51 - 32:54
and the presentation of almond
coinciding,
32:54 - 32:55
there are more cells in the nose
32:55 - 32:57
that express the almond
receptor.
32:57 - 33:00
It's as if something in
the milieu of the nose says,
33:00 - 33:02
almond's important
in this environment.
33:02 - 33:03
We need more cells like you.
33:04 - 33:06
BERLIN:
Mice grew more cells
33:06 - 33:09
that responded
to the smell of almond.
33:09 - 33:11
MARLIN:
Each one of these green
dots you see here,
33:12 - 33:13
these are neurons.
33:13 - 33:16
They're cells that can respond
to the almond smell.
33:17 - 33:20
These red dots are
cells that were born
33:20 - 33:22
after the presentation
of odor and shock.
33:23 - 33:27
And this cell right here,
this red and green cell,
33:27 - 33:28
is a cell that was born
33:28 - 33:30
after the presentation
of almond and shock
33:30 - 33:33
that also responds to almond.
33:33 - 33:35
This is the cell
that we want to look at
33:35 - 33:37
to see what information
is inside,
33:37 - 33:38
because we see more of these
33:39 - 33:40
after the odor and shock
pairing.
33:41 - 33:44
BERLIN:
Remarkably, these changes were
actually passed down
33:44 - 33:48
to the next generation.
33:48 - 33:50
MARLIN:
The offspring,
the kids of the parents
33:50 - 33:53
that were shocked with odor,
33:53 - 33:57
were born with more cells that
express the almond receptor.
33:57 - 33:58
Which means there's
a memory that somehow
33:58 - 34:02
is maintained in sperm
and egg through implantation
34:02 - 34:05
and represented in offspring.
34:05 - 34:09
It is as if we are
observing a change in evolution
34:09 - 34:14
over the time span of one
generation.
34:14 - 34:16
And I just
think that's fascinating.
34:16 - 34:19
Because we as humans know how
34:19 - 34:23
environment and how traumatic
events change people.
34:24 - 34:27
Just being able to take
the science of that
34:27 - 34:29
and being able to show that,
34:29 - 34:32
we're just justifying what we
already know as humans,
34:32 - 34:33
what society has known for a
long time,
34:33 - 34:35
what individuals know.
34:35 - 34:39
We just want to bring
that to an undeniable truth.
34:41 - 34:43
MARTINEZ-CONDE:
Our brains are not static.
34:43 - 34:47
We try to make sense of
what's happening right now,
34:47 - 34:52
but we also try to make sense of
what happened a long time ago
34:52 - 34:54
and to have, like, this grand
picture
34:54 - 34:56
of our life as a trajectory.
34:58 - 35:00
Our ability
for conscious awareness.
35:00 - 35:01
It's a magnificent ability,
this ability
35:01 - 35:03
to reflect on our own minds.
35:03 - 35:06
But it also leads us astray.
35:06 - 35:08
SETH:
I have memories, plans,
35:08 - 35:12
I have these feelings
of agency over my actions.
35:12 - 35:14
But what the science
itself is telling us is that
35:14 - 35:17
these things aren't
necessarily bound together.
35:17 - 35:19
Different aspects of
the self can be manipulated,
35:19 - 35:21
or even taken away altogether.
35:22 - 35:25
BERLIN:
Your biology
and the choices you make
35:25 - 35:27
are all molded by your social
interactions
35:27 - 35:30
and even your family history.
35:30 - 35:33
And yet,
we feel like we have control.
35:33 - 35:37
Like we have agency, right?
35:43 - 35:48
MAOZ:
An agent is somebody that is the
author of their own story.
35:49 - 35:51
But actually,
35:51 - 35:53
most of what's happening in our
brain we are not conscious of.
35:53 - 35:56
And I think this gets
you starting to think,
35:56 - 35:58
wait a minute, you know,
35:58 - 36:00
is really everything under my
control?
36:02 - 36:03
BERLIN:
Neuroscientist Uri Maoz
36:03 - 36:06
is putting our sense of control
to the test.
36:08 - 36:09
We feel like we're in control,
36:09 - 36:11
but where exactly does that
36:11 - 36:14
feeling come from,
and how does it work?
36:14 - 36:17
Ah, here you are.
36:19 - 36:21
Thank you very
much for joining us,
36:21 - 36:24
agent-ically
and out of your own volition.
36:24 - 36:26
(laughs):
Of course.
36:24 - 36:26
Before we start...
36:26 - 36:28
...let me give you
this envelope.
36:28 - 36:31
Please don't
let anybody touch it.
36:31 - 36:34
And don't look inside,
but we'll need it for later on.
36:34 - 36:35
For later, okay.
36:35 - 36:37
BERLIN:
To show me how my sense
of control
36:37 - 36:38
isn't always what it seems,
36:39 - 36:41
Uri kicked things off by trying
to get me
36:41 - 36:46
to question my ability to
choose by using a magic trick.
36:46 - 36:48
So where would
you like to sit?
36:48 - 36:49
Where would I like to sit?
36:49 - 36:51
MAOZ: It's really up to you.
36:49 - 36:51
BERLIN:
It's really-- I have a choice?
36:51 - 36:53
MAOZ:
Wherever you want--
you have a choice.
36:53 - 36:54
All right,
so I'm going to sit here.
36:55 - 36:56
You're going to sit
over there, okay.
36:56 - 36:58
So how about just before you sit
down, if you don't mind...
36:59 - 37:03
Um, let's see
what this says.
37:03 - 37:05
Oh, my God, okay.
37:05 - 37:09
So then that one obviously
says the same thing, right?
37:11 - 37:13
Let's check
and see what this one says.
37:13 - 37:16
This one says...
37:13 - 37:16
Oh, come on.
37:16 - 37:19
(laughs):
So I'm that predictable?
37:19 - 37:21
You don't even know me yet!
37:22 - 37:24
BERLIN:
I really don't know how
he did that!
37:24 - 37:29
I'm not totally convinced,
but I'm starting to question,
37:29 - 37:31
how do I know when
I have made a decision?
37:31 - 37:34
If I may,
let me give you,
37:34 - 37:35
as a present, a book.
37:35 - 37:37
Here you go, this is yours.
37:35 - 37:37
Oh, thank you.
37:37 - 37:39
And I will just ask
you to leaf through it...
37:39 - 37:42
...and find a word that has
some meaning for you.
37:42 - 37:44
All right, I got it.
37:44 - 37:45
Can you tell
me what the word is?
37:45 - 37:47
Representation.
37:47 - 37:49
Please write the word down,
representation.
37:49 - 37:51
And, you know,
just stick that sticky note
37:51 - 37:53
somewhere on that page,
yeah, thank you.
37:51 - 37:53
Okay, okay, all right.
37:53 - 37:55
BERLIN:
We'll come back to that later.
37:56 - 37:59
But for now,
I'm starting to see how choice
37:59 - 38:02
and agency aren't
always so straightforward.
38:03 - 38:06
So to find out what's
actually going on in the brain
38:06 - 38:08
when our sense of
control is in question,
38:08 - 38:10
I took a look
at a trial designed
38:10 - 38:13
by post-doctoral
researcher Alice Wong.
38:13 - 38:17
A volunteer from the lab,
Tomás, is being fitted
38:17 - 38:21
with a transcranial magnetic
stimulation device,
38:21 - 38:24
TMS for short.
38:24 - 38:27
It generates a strong magnetic
field
38:27 - 38:29
that can send
signals to your brain.
38:29 - 38:30
MAOZ:
The idea is that you
38:30 - 38:34
stimulate the brain using
a focused magnetic field.
38:34 - 38:37
And if you stimulate
that in the right part
38:37 - 38:41
of the motor cortex--
it's a part of the brain
38:41 - 38:43
that actually
controls your fingers--
38:43 - 38:44
it's like you're
pulling on a string here.
38:44 - 38:46
Every time you pull it,
the finger goes.
38:48 - 38:50
BERLIN:
With the device hooked up,
38:50 - 38:52
the researchers can make
his finger jump
38:52 - 38:56
involuntarily by sending
a signal to his motor cortex.
38:56 - 38:59
(device clicks)
38:56 - 38:59
WONG:
We're going to be locating
38:59 - 39:03
the spot of your motor cortex
that moves one of your fingers.
39:04 - 39:05
(device clicks)
39:05 - 39:06
How about that?
39:05 - 39:06
TOMÁS: That works.
39:06 - 39:09
That was a pinky movement up.
39:10 - 39:14
BERLIN:
Sometimes they ask him
to move his finger on his own.
39:14 - 39:17
WONG:
Could you replicate the movement
if in, that you...
39:17 - 39:19
TOMÁS:
Was something like this.
39:19 - 39:21
BERLIN:
Remarkably, by recording
39:21 - 39:24
the small electrical signals
that travel from his brain
39:24 - 39:26
down to his finger muscles,
39:26 - 39:29
Alice and Uri can pinpoint the
exact moment
39:29 - 39:32
that Tomás's brain has initiated
a movement--
39:32 - 39:36
almost 50 milliseconds
before he actually moves.
39:36 - 39:41
With this information, it's
as though they can predict
39:41 - 39:44
his movement slightly
before it actually happens.
39:44 - 39:49
So now, his sense of agency
is about to be put to the test.
39:49 - 39:50
WONG:
Who initiated the movement?
39:50 - 39:52
TOMÁS:
It was me.
39:52 - 39:54
WONG:
How much agency did you
feel over the movement?
39:54 - 39:55
TOMÁS:
Quite a lot.
39:55 - 39:57
Full agency? Okay.
39:57 - 40:00
BERLIN:
Normally, the researcher
isn't in the room,
40:00 - 40:04
and all the questions
are conducted by the computer.
40:04 - 40:06
Who initiated the movement?
40:08 - 40:11
I don't know.
40:11 - 40:14
How much agency did
you feel over the movement?
40:15 - 40:17
TOMÁS:
I would say some agency.
40:17 - 40:18
BERLIN:
In some instances,
40:18 - 40:23
just as Tomás decides
to move his finger,
40:23 - 40:25
the researchers use the magnetic
field to make his finger move.
40:25 - 40:27
(device clicks)
40:25 - 40:27
WONG:
Who initiated the movement?
40:27 - 40:30
I really don't know.
40:32 - 40:35
How much agency did
you feel over the movement?
40:35 - 40:37
A little bit.
40:37 - 40:39
BERLIN:
So, even in the instances
40:39 - 40:42
when Tomás really did decide
to move his finger...
40:42 - 40:44
WONG:
How much agency did you feel
40:44 - 40:47
over the movement?
40:44 - 40:47
No agency at all.
40:47 - 40:50
BERLIN:
...he didn't always
feel like he was in control.
40:50 - 40:54
So after the experiment, I was
excited to hear the results.
40:54 - 40:59
MAOZ:
When Tomás initiated
the movement himself,
40:59 - 41:02
yet we intervened with the TMS,
41:02 - 41:06
Tomás said, "That wasn't me,
I didn't initiate the movement.
41:06 - 41:09
It was the computer."
41:09 - 41:11
He thought that the computer
initiated the movement,
41:11 - 41:12
or it was both of them,
or he wasn't sure,
41:12 - 41:14
but he almost never
said that it was him.
41:15 - 41:17
BERLIN:
So what do you think is going
on there?
41:17 - 41:19
How is this happening?
41:19 - 41:21
MAOZ:
You know, we walk around
and we feel like, you know,
41:21 - 41:23
we are the authors of our,
of our actions and so on.
41:23 - 41:25
And you can see with just
a little bit of messing around,
41:26 - 41:27
it tends to fall apart.
41:27 - 41:30
BERLIN: It's fragile,
like our sense of self...
41:30 - 41:32
BERLIN:
...our memories,
our sense of agency.
41:32 - 41:35
They're all things that
our brain evolved over time.
41:35 - 41:38
BERLIN: But they're fragile
and they can be manipulated...
41:38 - 41:39
BERLIN:
...under the right
circumstances.
41:39 - 41:41
MAOZ:
Everything has to align
41:41 - 41:42
for you to feel the sense
of agency.
41:42 - 41:44
When the finger moves,
41:44 - 41:46
we get this feedback
back to the brain
41:46 - 41:48
and it's incorporated with
whatever is happening
41:48 - 41:49
in the brain
to create the movement.
41:49 - 41:53
MAOZ:
And together you get this sense
of agency over the movement.
41:53 - 41:57
I think that in everyday life,
we are in control.
41:57 - 42:00
However, I think this experiment
shows we're quite happy
42:00 - 42:02
to relinquish control.
42:02 - 42:04
BERLIN:
Like states of consciousness,
42:04 - 42:05
there are levels of agency,
42:05 - 42:10
ways it can be manipulated,
and even taken away.
42:10 - 42:13
We think A happened and then B
happened.
42:13 - 42:15
That's the end of the story.
42:15 - 42:18
But of course, most of our brain
activity is unconscious.
42:18 - 42:20
Who initiated the first
movement?
42:20 - 42:23
That was me.
42:23 - 42:24
SETH:
So, we sometimes misinterpret.
42:24 - 42:26
Our experience of
voluntary action
42:26 - 42:28
is a little bit
retrospective in this sense.
42:28 - 42:30
The brain looks at what
the body did,
42:30 - 42:32
and figures out if that makes
sense
42:32 - 42:35
as an act of its own free will.
42:36 - 42:39
BERLIN:
After the agency experiment,
42:39 - 42:41
we had more important
matters to attend to.
42:41 - 42:45
So, Heather, when you came in,
I gave you an envelope, right?
42:45 - 42:47
Nobody touched it but you?
42:48 - 42:51
Do you remember
that later on,
42:51 - 42:52
I gave you that book?
42:53 - 42:54
And in that book,
you opened it
42:54 - 42:58
to whatever page you wanted,
and you found a word in there.
42:58 - 43:00
Right, where the...
42:58 - 43:00
Can you tell
us again what that word was?
43:00 - 43:02
Yes, it was on page 105.
43:02 - 43:05
And the word was
"representation."
43:05 - 43:07
Representation, okay.
43:07 - 43:10
So if you don't mind just
putting the book aside
43:10 - 43:12
and if you could take the
envelope out now.
43:12 - 43:14
Can you open it and see
what's inside, please?
43:14 - 43:15
Oh, this is one of these things
43:16 - 43:18
that's gonna freak me out,
right?
43:16 - 43:18
Let's see.
43:18 - 43:19
I'm getting chills.
43:24 - 43:27
Come on. No way!
43:27 - 43:30
Come on-- no, seriously!
43:27 - 43:30
(both laugh)
43:30 - 43:32
That's really freaky.
43:32 - 43:34
So you're in control,
right?
43:34 - 43:37
I don't know how you did that--
that is really weird.
43:37 - 43:38
I mean, what do I do now?
43:38 - 43:41
(laughs):
I don't know where to--
what do I do with that?
43:41 - 43:43
BERLIN:
Uri's magic acts are tricks.
43:43 - 43:46
Sleights-of-hand
and misdirection.
43:46 - 43:48
But when I saw what
was written on the card,
43:48 - 43:52
I have to admit I wondered
if my choices mattered at all.
43:52 - 43:55
Going to do this...
43:55 - 43:56
BERLIN:
Alice Wong's experiment supports
43:56 - 43:59
the idea that it isn't just
about what happens in the brain
43:59 - 44:01
at the moment
a decision is made.
44:01 - 44:03
How did you do that?
44:03 - 44:05
BERLIN:
Your sense of agency
or control
44:05 - 44:09
also has to do with feedback
you get after the decision--
44:09 - 44:12
physical, social, and emotional.
44:12 - 44:15
I think of agency as a sense,
so there is a sense of agency
44:15 - 44:18
that sometimes
can get disrupted, perhaps,
44:18 - 44:20
just like you have a sense
of sight or smell and so on.
44:20 - 44:22
Sometimes,
you have visual illusions.
44:22 - 44:24
It's similar
with a sense of agency.
44:24 - 44:27
I can manipulate
your sense of agency.
44:27 - 44:28
But that doesn't
mean that we never
44:28 - 44:30
have a sense of agency.
44:32 - 44:34
BERLIN:
Your brain is
a meaning-maker machine.
44:34 - 44:37
And creating a sense of agency
44:37 - 44:40
is one of the ways it makes
meaning out of your daily life.
44:42 - 44:45
BANAJI:
There is no way in
which I can operate
44:45 - 44:46
without understanding
44:46 - 44:49
what is happening
and why I'm doing it.
44:49 - 44:53
It's the filling-in of
the blanks that is necessary
44:53 - 44:55
in some ways for survival,
to give meaning, to make sense
44:55 - 44:58
of the cause and effect of
things.
44:58 - 45:00
KASTHURI:
Perhaps we have
that feeling of consciousness
45:00 - 45:03
because it gives
me a sense of agency.
45:03 - 45:07
It allows me to pretend like
I'm the one making decisions
45:07 - 45:08
and I'm the one
reaping the rewards
45:09 - 45:12
or the failures
of that particular decision.
45:12 - 45:15
BERLIN:
There are parts of the brain
that allow you
45:15 - 45:18
to feel like
the author of your own life.
45:18 - 45:20
But that's
only part of the story.
45:20 - 45:22
(echoing):
Each of our minds is
actually composed
45:22 - 45:24
of lots of different pieces
that are doing different things.
45:24 - 45:27
This illusion
that there's a single person
45:27 - 45:29
inside our skulls.
45:29 - 45:31
MARLIN:
We know how environment
45:31 - 45:34
and how traumatic events change
people.
45:34 - 45:36
Our brains are, in detail,
influenced
45:36 - 45:39
by the expectations
of the people around us.
45:39 - 45:44
But of course, most of our brain
activity is unconscious.
45:44 - 45:46
(playing slow tune)
45:46 - 45:49
BERLIN:
But there are some situations
where letting go
45:49 - 45:52
of conscious control
can have amazing results.
45:55 - 45:57
LIMB:
When you're playing the blues,
45:57 - 45:59
you have this kind of
well-known musical structure,
45:59 - 46:01
this template,
and then you use that
46:01 - 46:02
as a launchpad
for improvisation,
46:02 - 46:05
for innovation,
and for new ideas.
46:05 - 46:08
BERLIN:
Charles Limb is a neuroscientist
46:08 - 46:11
trying to understand how our
brain operates
46:11 - 46:13
when we are being truly
creative.
46:13 - 46:16
CHRIS EMDIN:
♪ It's gon' be ill in the MRI ♪
46:16 - 46:18
BERLIN:
And today,
46:18 - 46:20
he's using a scanner to peer
into the brain
46:20 - 46:23
of educator and freestyle
rapper Chris Emdin.
46:23 - 46:26
♪ I wonder if I'm going insane
as I'm freestyling, profiling ♪
46:26 - 46:28
♪ Still wilin',
it's gon' be ill ♪
46:28 - 46:30
You ready for me?
46:33 - 46:35
LIMB:
Okay, remember,
keep your head still
46:35 - 46:38
during the entire thing
and try not to move your feet
46:38 - 46:40
or your hands
at all during the rapping.
46:40 - 46:41
EMDIN (on speaker):
Okay, doing the best I can.
46:41 - 46:43
Yeah, awesome,
thank you.
46:43 - 46:48
BERLIN:
First, Charles asks Chris
to perform a memorized piece.
46:48 - 46:50
Now, that memory means you're
going to do the memorized lyrics
46:50 - 46:52
the way
you originally wrote them.
46:52 - 46:55
EMDIN: Okay.
46:55 - 46:56
LIMB:
Memory.
46:56 - 46:59
EMDIN:
♪ I'm a physicist, lyricist,
spitting this ridiculousness ♪
46:59 - 47:01
♪ So witness the ignorance
I dismiss ♪
46:59 - 47:01
Up a little bit?
47:01 - 47:03
♪ Feelings and emotion
is the topic of the course ♪
47:03 - 47:06
♪ Staying motionless
to handle balanced force ♪
47:06 - 47:09
BERLIN:
Next, he gives him
a prompt and asks him
47:09 - 47:14
to improvise-- to create a new,
original piece on the spot.
47:14 - 47:16
He doesn't know what's coming.
47:16 - 47:18
And that's going
to be his cues for that.
47:18 - 47:20
LIMB:
Freestyle: physicist.
47:20 - 47:23
EMDIN:
♪ Physicist, lyricist ♪
47:23 - 47:25
♪ Emcees like this
will always be kicking this ♪
47:25 - 47:26
♪ After all of
that it'll all be over ♪
47:26 - 47:30
♪ Lucky like I picked
a four-leaf clover ♪
47:30 - 47:32
♪ Can't move my shoulder ♪
47:32 - 47:34
♪ 'Cause the MRI machine won't
let me do it ♪
47:34 - 47:36
♪ But you wouldn't know
what it is that it's like ♪
47:36 - 47:39
♪ I'm like a baseball player
the way I strike ♪
47:39 - 47:41
♪ With the raps... ♪
47:41 - 47:42
(chuckles):
He's good.
47:44 - 47:47
BERLIN:
So, what does improvisation
or spontaneous creativity
47:47 - 47:50
look like in the brain?
47:50 - 47:51
LIMB:
What we found was that
47:51 - 47:55
the prefrontal cortex
that appears to be linked
47:55 - 47:58
to effortful self-monitoring
47:58 - 48:00
seemed to be turning off,
48:00 - 48:03
deactivating, in a pretty
intense way
48:03 - 48:05
in these highly trained
professional musicians
48:05 - 48:07
when they start improvising.
48:07 - 48:12
So in some sense, by letting go,
by decreasing activation
48:12 - 48:14
in the prefrontal cortex,
48:14 - 48:17
we can sort of gain control
of our lives in a way.
48:17 - 48:19
LIMB:
In fact, if you're
too self-conscious
48:19 - 48:21
and you're unable
to relax and let go,
48:21 - 48:23
you can't do
something like this.
48:23 - 48:26
When you start trying to put
conscious control mechanism,
48:26 - 48:27
your performance goes down--
you get worse.
48:27 - 48:29
So would you say this
goes to, to any activity,
48:29 - 48:32
really, if you're,
for a professional tennis player
48:32 - 48:34
or if you're trying
to do a physical activity,
48:34 - 48:37
that the more you're
able to practice letting go,
48:37 - 48:40
once you've learnt the skill,
the better you'll be.
48:40 - 48:44
LIMB:
Free throw shooters that are
able to shoot 99% free throws,
48:44 - 48:46
all of a sudden,
when you tell them
48:46 - 48:48
you're going to get a million
dollars
48:48 - 48:49
if you make the next one...
48:49 - 48:52
Then all of a sudden, you inject
conscious control over something
48:52 - 48:54
that's much better just to left
to its own subconsciousness.
48:54 - 48:56
And then your performance gets
worse,
48:56 - 48:57
and you're more likely to choke.
48:57 - 49:00
BERLIN:
Surprisingly,
the parts of your brain
49:00 - 49:04
that are usually in control
can get in your way.
49:04 - 49:07
Your prefrontal cortex,
the decision maker,
49:07 - 49:11
can make you overthink something
you've done a thousand times.
49:13 - 49:15
LIMB:
Freestyle: stay.
49:15 - 49:17
EMDIN:
♪ Yes, you want me to stay ♪
49:17 - 49:19
♪ Relaxed,
but I won't never play ♪
49:19 - 49:23
LIMB:
Every human being is creative.
49:23 - 49:24
Whether they're
creative artistically or not
49:24 - 49:27
is another question,
but we're all creative.
49:27 - 49:29
We have to be, because
all day long, we're doing
49:29 - 49:31
unscripted things that we
didn't know we would be doing.
49:31 - 49:34
Life is not scripted.
49:34 - 49:35
And so no matter who you are
49:35 - 49:39
in this world, you're doing
things that are unplanned.
49:40 - 49:42
BERLIN:
All day long,
we're balancing forces
49:42 - 49:45
that push us around,
even if we're not aware of them,
49:45 - 49:49
from past trauma
to the emotions of others,
49:49 - 49:52
and all the hidden
forces affecting your brain.
49:52 - 49:55
KASTHURI:
I'd like to believe
that I am in charge of my life,
49:55 - 49:58
that I am the agent of my life,
49:58 - 50:00
that I actually can control my
emotions,
50:01 - 50:03
my abilities, my desires.
50:03 - 50:05
And the more I learn
about brains, the more I realize
50:05 - 50:07
that this is probably not true.
50:08 - 50:10
SETH:
We can be influenced
by our social networks,
50:10 - 50:13
by our culture, by our genetics,
50:13 - 50:17
by our development,
by our childhood.
50:17 - 50:19
(clock ticking)
50:19 - 50:21
BERLIN:
Your brain is a complicated
collection
50:21 - 50:24
of these intricate parts,
50:24 - 50:26
many of which
you have no awareness of,
50:26 - 50:29
and they all work together
in a delicate dance
50:29 - 50:33
to create your perception
of you.
50:33 - 50:36
KANWISHER:
The brain is who you are.
50:36 - 50:38
It's really different than
any other organ in that sense.
50:39 - 50:41
MARTINEZ-CONDE:
We know that every experience,
50:41 - 50:44
every thought, every memory,
50:44 - 50:48
every sensation has
its origin in the brain.
50:49 - 50:52
KASTHURI:
The brain is made of almost
90 billion neurons,
50:52 - 50:53
but it produces the idea
50:53 - 50:56
that there's a single thing
inside my head.
50:56 - 50:58
My particular
pattern of neuronal connections,
50:58 - 51:00
it actually creates me.
51:00 - 51:02
And your particular pattern
of neuronal connections
51:02 - 51:06
actually creates you.
51:06 - 51:09
BERLIN:
Years of studying the brain
have humbled me.
51:09 - 51:11
BERLIN:
He looks scared.
51:11 - 51:13
BERLIN:
You can't control everything
51:13 - 51:16
that makes you who you are.
51:16 - 51:20
But the unconscious
you is still you.
51:20 - 51:23
BANAJI:
The vast majority
51:23 - 51:27
of the brain's work is happening
outside conscious awareness.
51:27 - 51:29
(crowd groans)
51:27 - 51:29
LIMB: If you try to
over-control some things,
51:29 - 51:31
you actually will
decrease your performance.
51:31 - 51:34
LIMB:
You have to let go
51:34 - 51:36
of conscious self-monitoring
to just kind of, like,
51:36 - 51:38
go with the flow.
51:38 - 51:40
It could be scary to say
and scary to hear,
51:40 - 51:42
but we are not just our own.
51:43 - 51:46
WHEATLEY:
We are all multifaceted,
multi-dimensional people.
51:47 - 51:49
BERLIN:
And by becoming more aware
51:49 - 51:53
of the unconscious processes in
your own brain,
51:53 - 51:55
you can become more aware
of what drives you,
51:55 - 52:00
and what you ultimately
can control.
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