♪ ♪ 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 90 billion neurons.

This illusion that there's a single person inside our skulls.

♪ ♪ BERLIN: Inside your brain are over 100 distinct regions.

Many different systems in the brain control what you do, from movement, to vision, to speech, and even social interaction.

MAHZARIN BANAJI: I think most human beings like to believe that their mind is under their own control.

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

I can do that.

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 War II.

MARLIN: At the end of World War II, the Netherlands were cut off from food by Nazi troops because they decided to protest through the country.

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

There was starvation, death, there was trauma.

BERLIN: Not only did those who suffered during the famine experience health problems, but some of their children, and even their grandchildren, had metabolic issues.

So people began to ask, how does an experience of a parent, of a grandparent, change offspring?

BERLIN: Researchers began to discover that your environment and your experiences can change the way your genes are activated in your body and in your brain.

MARLIN: It's not like you get your genes and it's set in stone.

They're constantly changing based on the environment.

BERLIN: To see this in action, Bianca studies mice.

MARLIN: We're able to map the whole genome of mice, target certain areas of that genetic code, and use them to answer important questions in science.

BERLIN: So how could stress and trauma alter the biology of the mice's offspring?

To find out, Bianca paired the smell of almond with an electric shock.

(shock buzzes) MARLIN: Because mice really navigate the world and rely heavily on the sense of smell, we use olfaction, pair it with a light foot shock, and we observe changes in the brain and changes in behavior.

BERLIN: She noticed that something inside of the mice's noses changed.

MARLIN: We're able to look at the cells in the nose that only respond to almond.

And what we observe is that after the light foot shock and the presentation of almond coinciding, there are more cells in the nose that express the almond receptor.

It's as if something in the milieu of the nose says, almond's important in this environment.

We need more cells like you.

BERLIN: Mice grew more cells that responded to the smell of almond.

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

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

These red dots are cells that were born after the presentation of odor and shock.

And this cell right here, this red and green cell, is a cell that was born after the presentation of almond and shock that also responds to almond.

This is the cell that we want to look at to see what information is inside, because we see more of these after the odor and shock pairing.

BERLIN: Remarkably, these changes were actually passed down to the next generation.

MARLIN: The offspring, the kids of the parents that were shocked with odor, were born with more cells that express the almond receptor.

Which means there's a memory that somehow is maintained in sperm and egg through implantation and represented in offspring.

It is as if we are observing a change in evolution over the time span of one generation.

And I just think that's fascinating.

Because we as humans know how environment and how traumatic events change people.

Just being able to take the science of that and being able to show that, we're just justifying what we already know as humans, what society has known for a long time, what individuals know.

We just want to bring that to an undeniable truth.

MARTINEZ-CONDE: Our brains are not static.

We try to make sense of what's happening right now, but we also try to make sense of what happened a long time ago and to have, like, this grand picture of our life as a trajectory.

Our ability for conscious awareness.

It's a magnificent ability, this ability to reflect on our own minds.

But it also leads us astray.

SETH: I have memories, plans, I have these feelings of agency over my actions.

But what the science itself is telling us is that these things aren't necessarily bound together.

Different aspects of the self can be manipulated, or even taken away altogether.

BERLIN: Your biology and the choices you make are all molded by your social interactions and even your family history.

And yet, we feel like we have control.

Like we have agency, right?

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

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

And I think this gets you starting to think, wait a minute, you know, is really everything under my control?

BERLIN: Neuroscientist Uri Maoz is putting our sense of control to the test.

We feel like we're in control, but where exactly does that feeling come from, and how does it work?

Ah, here you are.

Hello.

Hello.

Thank you very much for joining us, agent-ically and out of your own volition.

(laughs): Of course.

Before we start... Mm-hmm.

...let me give you this envelope.

Okay.

Please don't let anybody touch it.

Okay.

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

For later, okay.

BERLIN: To show me how my sense of control isn't always what it seems, Uri kicked things off by trying to get me to question my ability to choose by using a magic trick.

So where would you like to sit?

Where would I like to sit?

MAOZ: It's really up to you.

BERLIN: It's really-- I have a choice?

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

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

You're going to sit over there, okay.

Yes.

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

Um, let's see what this says.

Oh, my God, okay.

So...

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

Um... No?

Let's check and see what this one says.

This one says... Oh, come on.

Okay.

(laughs): So I'm that predictable?

You don't even know me yet!

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

I'm not totally convinced, but I'm starting to question, how do I know when I have made a decision?

If I may, let me give you, as a present, a book.

Here you go, this is yours.

Oh, thank you.

And I will just ask you to leaf through it... Mm-hmm.

...and find a word that has some meaning for you.

All right, I got it.

Can you tell me what the word is?

Representation.

Please write the word down, representation.

Mm-hmm.

And, you know, just stick that sticky note somewhere on that page, yeah, thank you.

Okay, okay, all right.

BERLIN: We'll come back to that later.

But for now, I'm starting to see how choice and agency aren't always so straightforward.

So to find out what's actually going on in the brain when our sense of control is in question, I took a look at a trial designed by post-doctoral researcher Alice Wong.

A volunteer from the lab, Tomás, is being fitted with a transcranial magnetic stimulation device, TMS for short.

It generates a strong magnetic field that can send signals to your brain.

MAOZ: The idea is that you stimulate the brain using a focused magnetic field.

And if you stimulate that in the right part of the motor cortex-- it's a part of the brain that actually controls your fingers-- it's like you're pulling on a string here.

Every time you pull it, the finger goes.

BERLIN: With the device hooked up, the researchers can make his finger jump involuntarily by sending a signal to his motor cortex.

(device clicks) WONG: We're going to be locating the spot of your motor cortex that moves one of your fingers.

(device clicks) How about that?

TOMÁS: That works.

That was a pinky movement up.

WONG: Okay.

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

WONG: Could you replicate the movement if in, that you... TOMÁS: Was something like this.

BERLIN: Remarkably, by recording the small electrical signals that travel from his brain down to his finger muscles, Alice and Uri can pinpoint the exact moment that Tomás's brain has initiated a movement-- almost 50 milliseconds before he actually moves.

With this information, it's as though they can predict his movement slightly before it actually happens.

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

WONG: Who initiated the movement?

TOMÁS: It was me.

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

TOMÁS: Quite a lot.

Full agency?

Okay.

BERLIN: Normally, the researcher isn't in the room, and all the questions are conducted by the computer.

Who initiated the movement?

I don't know.

How much agency did you feel over the movement?

TOMÁS: I would say some agency.

BERLIN: In some instances, just as Tomás decides to move his finger, the researchers use the magnetic field to make his finger move.

(device clicks) WONG: Who initiated the movement?

I really don't know.

Okay.

How much agency did you feel over the movement?

A little bit.

BERLIN: So, even in the instances when Tomás really did decide to move his finger... WONG: How much agency did you feel over the movement?

No agency at all.

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

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

MAOZ: When Tomás initiated the movement himself, yet we intervened with the TMS, Tomás said, "That wasn't me, I didn't initiate the movement.

It was the computer."

He thought that the computer initiated the movement, or it was both of them, or he wasn't sure, but he almost never said that it was him.

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

How is this happening?

MAOZ: You know, we walk around and we feel like, you know, we are the authors of our, of our actions and so on.

And you can see with just a little bit of messing around, it tends to fall apart.

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

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

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

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

BERLIN: ...under the right circumstances.

MAOZ: Everything has to align for you to feel the sense of agency.

When the finger moves, we get this feedback back to the brain and it's incorporated with whatever is happening in the brain to create the movement.

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

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

However, I think this experiment shows we're quite happy to relinquish control.

BERLIN: Like states of consciousness, there are levels of agency, ways it can be manipulated, and even taken away.

We think A happened and then B happened.

That's the end of the story.

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

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 shoot 99% free throws, all of a sudden, when you tell them you're going to get a million dollars if you make the next one... Mm-hmm.

Then all of a sudden, you inject conscious control over something that's much better just to left to its own subconsciousness.

And then your performance gets worse, and you're more likely to choke.

BERLIN: Surprisingly, the parts of your brain that are usually in control can get in your way.

Your prefrontal cortex, the decision maker, can make you overthink something you've done a thousand times.

LIMB: Freestyle: stay.

EMDIN: ♪ Yes, you want me to stay ♪ ♪ Relaxed, but I won't never play ♪ LIMB: Every human being is creative.

Whether they're creative artistically or not is another question, but we're all creative.

We have to be, because all day long, we're doing unscripted things that we didn't know we would be doing.

Life is not scripted.

And so no matter who you are in this world, you're doing things that are unplanned.

BERLIN: All day long, we're balancing forces that push us around, even if we're not aware of them, from past trauma to the emotions of others, and all the hidden forces affecting your brain.

KASTHURI: I'd like to believe that I am in charge of my life, that I am the agent of my life, that I actually can control my emotions, my abilities, my desires.

And the more I learn about brains, the more I realize that this is probably not true.

SETH: We can be influenced by our social networks, by our culture, by our genetics, by our development, by our childhood.

(clock ticking) BERLIN: Your brain is a complicated collection of these intricate parts, many of which you have no awareness of, and they all work together in a delicate dance to create your perception of you.

KANWISHER: The brain is who you are.

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

MARTINEZ-CONDE: We know that every experience, every thought, every memory, every sensation has its origin in the brain.

KASTHURI: The brain is made of almost 90 billion neurons, but it produces the idea that there's a single thing inside my head.

My particular pattern of neuronal connections, it actually creates me.

And your particular pattern of neuronal connections actually creates you.

BERLIN: Years of studying the brain have humbled me.

BERLIN: He looks scared.

BERLIN: You can't control everything that makes you who you are.

But the unconscious you is still you.

BANAJI: The vast majority of the brain's work is happening outside conscious awareness.

(crowd groans) LIMB: If you try to over-control some things, you actually will decrease your performance.

LIMB: You have to let go of conscious self-monitoring to just kind of, like, go with the flow.

It could be scary to say and scary to hear, but we are not just our own.

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

BERLIN: And by becoming more aware of the unconscious processes in your own brain, you can become more aware of what drives you, and what you ultimately can control.

♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪