How Do I Decide? The Brain with David Eagleman

There's a lot of noise in this operating theatre,

but I want you to listen out for something.

In preparation for this patient's neurosurgery,

doctors have put electrodes into his brain to record the activity.

Through a speaker, we can hear the firing of individual neurons.

He's agreed to help me with an experiment about decision-making.

OK.

Can you tell me what you're seeing? So this is very simple.

'Without him knowing it,

'his brain will decide whether this is a rabbit, or an ostrich.

'It could be seen as either.'

What do you say, an ostrich?

'As his brain comes to a decision,

'there's a subtle change in the audio.

'It's buried in that pup-pup-pup.'

SCRATCHING SOUND

This is the sound of a decision getting made.

We're eavesdropping on single neurons working in consult

with billions of other neurons to land on a choice.

And this is what every decision

in the history of the human species looks like.

Every marriage proposal, every declaration of war,

every leap of imagination, every mission we've launched,

every bit of human magic looked just like this.

'Our brains are constantly making decisions.

'Some we're aware of, most we're not.

'Deciphering what we hear or see or smell, these are decisions.

'So is being afraid, falling in love,

'giving in, resisting.

'Decision-making is what allows us to navigate a course through life.

'And your lifetime of choices has sculpted you into the person

'you are right now.'

'No matter how easy your day seems, your brain is always hard at work.

'Making choices, weighing up different options.

'And it's often in a state of conflict.

'Locked in a great power struggle with itself.

'Let me show you what I mean.

'Right now, I have to make a momentous decision.

'Mint frozen yoghurt, or lemon?

'This is serious business because I like both.'

And inside my brain, this choice unleashes a whirlwind of activity.

Neurons are wildly getting in touch with one another.

They're forming competing networks.

One favours the zing of the zesty lemon.

The other, the freshness of the mint.

'When I finally go for the lemon, I have no real idea why I chose it.

'But if I could see under the hood, I would find

'that the lemon network has fought harder and won,

'squelching my mint network.'

But it's not just mint versus lemon.

I'm wondering whether to eat this yoghurt at all.

Because part of me wants it,

but part of me knows that it's fattening.

And it's because of this sort of conflict that we can get

angry at ourselves and cuss at ourselves and cajole ourselves.

Who's talking with whom, exactly?

It's only you, right? But it's different parts of you.

These rivalries are with us in every decision that we make.

They're usually so easily resolved that we're unaware of them.

But in some situations, they show themselves.

We can feel the tug of different networks.

'I'll show you what I mean.

'If I can find a willing volunteer.'

Excuse me, do you want to participate in an experiment?

-I don't think so.

-OK.

Excuse me, do you guys want to participate in an experiment?

This will only take 30 seconds.

-We're running late.

-OK. OK.

-Would you participate in an experiment for 30 seconds?

-OK.

-OK.

So here's what you're going to do. Put your hands out, OK,

-and I'm going to ask you to name the colour of the ink.

-OK.

-OK, so, what colour is that ink?

-Red.

-Good. OK.

-What colour is that ink?

-Blue.

'This is a pretty easy task.'

Green. Red.

'But introduce a conflict between the word

'and the colour of the ink and the situation changes.'

Blue. Yellow.

Orange. Orange.

Blue.

-DAVID CHUCKLES

-Green.

-Er...blue.

-OK.

Orange. Green.

Blue. Er...

THEY CHUCKLE

Orange.

Blue.

-Green.

-THEY LAUGH

-I had to close my eyes!

-Yeah, I saw that.

It's hard because of rivalries playing out inside the brain.

One network is involved in naming colours,

another has a lifetime of training in reading words.

'With both networks battling it out,

'you can directly experience the conflict.

'To get the right answer, you have to actively suppress

'the word-reading to name the colour.

'There are occasions when rival networks can't be reconciled.

'And those offer a special insight.'

In this rare footage,

we can see conflict in the brain expressing itself in the body.

Psychologist Matt Roser is a specialist in a condition

known as alien hand syndrome.

This is a rare side effect of a split-brain surgery

which is sometimes used to treat epilepsy.

Split-brain surgery is the disconnection of the two

hemispheres of the brain, the two halves of the brain.

By cutting the brain in half, you control the epilepsy better.

In this patient, it has further disturbing consequences.

It affects all her motor skills,

particularly the movement of her hands.

She can do what the doctor asks with one half of her body.

Can you lift your hands up in the air?

But she has no conscious control of the other half.

Can you give me a thumbs up with this hand? Give me a thumbs up.

Show me the index finger...

Her right brain takes control of her left hand and fights for attention.

What's going on? Tell us what's going on.

Can you show me your pinkie? OK, great.

Can you take your pinkie and touch your forehead, please?

The hand just doesn't respond to commands.

It seems to have a will of its own.

Because now there are almost like two half patients inside one body.

Can you show me your thumb? Show me your thumb.

For this patient,

her alien hand syndrome was eventually brought under control.

'Something's wrong!'

But the disorder reveals something that's normally hidden.

giving us a window into the struggle

that's waged inside our heads every day.

Can you show me your thumb? Show me your thumb.

In the business of decision-making,

two big systems that often come into conflict

are those we can summarise as reason and emotion.

These systems work together, so we're generally not aware

that more than one thing steers our decisions.

'But some situations can tease them apart.

'Consider the trolley dilemma.'

-Hi.

-Hi.

-I'd like to invite you to step into this booth here

and we're going to show you a video and just ask you

-a question about what you would do in this sort of scenario.

-OK.

You see a train trolley whose brakes are broken.

It's barrelling down the track out of control.

In its path, you see four workers.

They're too far away to warn, but if you don't do something,

they face certain death.

Then you see a lever.

If you pull it, you'll divert the trolley onto another track

and those four workmen will be saved.

But here's the thing. Another man is working on the other track.

If you pull the lever, he will definitely die.

So, do you pull the lever?

What do I do now?

-OK, did you pull the lever?

-I pulled the lever.

-OK, great.

Now here comes scenario two. There's one more scenario.

OK, great. Here we go.

This time, the dilemma is slightly different.

There are still four workers in the path of the out-of-control trolley.

But now there's no lever, no way to divert the trolley.

Instead, there's a large man standing on a water tower

next to the track.

Push him off into the trolley's path

and his weight will be enough to stop the trolley.

You'll be sacrificing one to save the others.

So, do you push the man?

-OK, did you push the man off?

-Absolutely not.

-What did you do in the first scenario? Pull the lever?

-I pulled the lever.

Because it's trading one life for four lives, right?

So, what's the difference between the two scenarios?

The physical crime tag of causing death,

even though I could see where they were the same thing,

they would have the same results,

my gut feeling was...was adverse to that.

Everyone I ask makes the same choice.

They'll pull the lever, but they won't push the man.

OK. HE LAUGHS

It's the same ethical dilemma in both cases.

Would you trade one life for four?

In the first scenario, it's just a math problem.

In the second one, you have to physically interact

with the man, push him to his death.

And that recruits other networks in the brain involved in emotion.

So, what's going on behind the scenes?

The conflict is being played out across the brain.

At first, the logic system dominates.

But introduce the idea of killing a man with your bare hands

and the emotion system comes online, tipping the balance.

You're caught between competing drives,

with the result that your decision can change entirely.

The trolley dilemma sheds light on real-world situations.

Think about modern warfare.

When you launch a long-range missile or pilot a drone,

or program a cyber attack, these cause damage at a distance.

The rational networks are at work,

but not necessarily the emotional networks.

Detachment reduces internal conflict.

It's more like pulling the lever than pushing the man.

War is easier to wage at a distance.

If we're capable of bypassing our emotional systems,

why do we have them at all?

So often in neuroscience, we learn most about the brain

when things go wrong.

For two decades, Tammy Myers had a successful career

as an engineer and a happy marriage.

Then, two years ago, there was an accident.

That morning, we got up and rode about an hour.

From what my friends tell me,

we went into a 90-degree turn that was not marked.

And, um...

..tried everything we could to get around the turn, the bike went down.

From there, I don't remember anything.

Tammy recovered from the crash, but one problem remained.

We're going to need four, cos...

She now struggles to make even the simplest decisions.

I don't... I don't...

I don't...I don't care.

I'm going to start crying and I don't want to cry.

But there's too many things in there.

There's good days and there's bad days

and you don't necessarily know what day it's going to be

when you wake up in the morning.

'I'm waiting for the day that...'

You know, that she's normal.

I can't make any... It's too many things

for my brain to process.

That sounds absolutely stupid!

SHE SOBS

Tammy's brain damage is in the prefrontal cortex.

Her logic and emotion systems have become disconnected.

They're still working,

but her emotions are no longer linked to her intellect.

Tammy's injury reveals that even in the most basic situations,

emotion is a necessary component of decision-making.

To understand the damage, Tammy's neurologist, Dr Eslinger,

has brought her here, to the grocery store.

'Tammy still experiences some level of emotional expression.'

She said it's very kind of elementary in a way.

And it's not linked into the logical system.

I don't understand what the difference is of all these things.

Right, if I forget things, I'll get my husband to pick 'em up...

Eslinger wants to see how Tammy copes with the most basic choices.

What should she buy for dinner?

So here you have some choices.

How do you decide what it is you would like?

Um...I just look at different things that are here.

And the different prices. I don't want baked potatoes.

I'd probably just pick up a bag of...

..maybe the gold potatoes, or...

'She was taking in the information accurately about what she was seeing

'and the fact there was cost and size and colour.'

So her brain was processing all the logical information, but the

emotion system wasn't coming into play, linking to that logic system.

There's so many. Why do you need so many potatoes?

-Ha! My chest is all tight thinking about all this.

-Why is that?

Because it's stress. It's a decision.

It's...it's, um...

There's a lot of stuff laying here.

'Tammy quickly became overwhelmed with information

'that she couldn't prioritise.'

The route that she took was,

"Let me take that one and get out of here".

I can't process the information.

-It's too much.

-Now, was that true before your accident?

No, no. I was an engineer.

I could do everything. But now I can't.

I can't pick a ham, let alone make ten decisions at work

within the next hour. Ten decisions maybe in the week.

The situation makes Tammy stressed,

but she can't make herself care about her choices.

To make a decision,

she needs to somehow value one option over another.

That's a lot of information to process.

And that can only be done with the help of the emotions.

It's information that you have to put into your head...

'The logical brain system still is very strong.

'And we want to force it to tap into the emotion system.'

So one of the things we do day-to-day

is we discard things that are not so important.

And sometimes it's our emotions that help us do that separation.

By having that logical brain system work on the process,

we may be able to break through,

at least in some ways, to reconnect those.

'I don't know what tomorrow is. Am I going to be better?

'Am I going to be worse?'

It seems like the pieces of the puzzle could be coming

together in a gradual fashion,

but it's really slow as far as my past being would have accepted.

'Tammy's story shows how important emotions are in making decisions.

'But here's the thing - emotions don't just happen inside the brain.

'Our emotional systems interact with the rest of our physiology.

'When we're faced with choices, our muscles imperceptibly tense.

'Our hormone levels fluctuate.

'These are automatic physical reactions.

'Gut feelings. And we need them.'

I'm trying to decide what kind of soup I want,

but it's a really difficult choice.

There's so many details for my brain to compute.

There's calories and price and taste and salt and packaging.

There are a millions details here

and I'm going to be paralysed all day under this mountain of data.

So what I really need is some sort of summary, a quick read.

And that's what the physiologic states of my body give me.

It allows me to put a value on this choice and a value on that choice.

And that's what allows me to make the decision.

'This conversation between the body and the brain never stops.

'But it really comes to the fore when we're stressed, or in danger.

'Take this situation.

'Before I think rationally about what's going on, I react physically.

'My sweat glands open.

'My heart rate increases.

'My pupils dilate. My body's screaming a simple message.

'Get me out of here!'

Every day, we experience emotional states like this,

but because they're mostly subtle and unconscious,

we're not typically aware of them.

But it turns out these states are crucial for navigating

all the decisions in our life.

'Most of us tend to distrust decisions based on feelings

'rather than intellect.

'So it can be surprising to learn just how much insight

'feelings can give us.'

Richard Tunney is an experimental psychologist.

He studies the formation of unconscious decisions.

He's running an experiment known as the Iowa Gambling Task.

I need you to keep your hands still.

Because that will affect the measurements we make.

A volunteer chooses to draw a card from one of four decks.

Each time she draws a card, she wins some amount of money

and she loses some.

Her task is to earn as much as possible.

As she plays, she's hooked up a machine similar to a lie-detector.

It monitors tiny changes in the sweat glands in her skin.

What she doesn't know is that the decks are not random, but rigged.

If she keeps choosing from decks A and C,

she'll end up making the most money.

The question is, how long before she figures that out?

The participant will explore the decks in the first instance

and they'll choose from all four decks.

They don't really begin to choose from the good decks consciously

until in the region of 20-30 cards.

But here's the thing -

the monitor indicates that volunteers figure out

which decks are good and bad much earlier.

After only ten tries, there's a spike of activity,

a warning sign whenever she reaches for the bad decks.

She doesn't realise it, but that's the beginnings of a hunch,

an understanding that her body registers before her conscious mind.

What we're seeing here is we're seeing

some physiological response prior to making the decision.

This spike here, in effect, predicts the choice

the participant is going to make.

As her hunch grows stronger, she marries logic

to what her body's been telling her.

Which decks to draw from and which to avoid.

OK, can I stop you there for a moment?

Can I ask you, if you were to choose any one of those four decks

for the rest of the experiment, which one would you choose?

I think I would choose deck C.

OK. Carry on.

It may feel like a logical deduction,

but it's built on a physical foundation.

The body and the brain are all integral to one another.

It's all part of the same system.

If physiology always plays a part in our decision-making,

what does that say about us?

Do we ever act in a purely rational way?

Or is that simply an illusion that we cling to?

Well, consider this -

if you ever come before a parole board, keep an eye on the clock.

We would all hope that Lady Justice is impartial,

but studies say otherwise, in a way that might surprise you.

Two men come up for parole on the same day, but three hours apart.

They've committed the same offence and served the same sentence.

So, what does the judge decide?

Now, here's what happened.

The first prisoner was granted parole and the second was denied.

Why? Given the crime was the same, what influenced the decision?

Was it race, age, looks?

Well, one study analysed 1,000 rulings from different judges

and they found it wasn't about those factors, it was about this.

'According to the research,

'prisoners were three times more likely to be given parole

'just after lunch, when board members were well fed,

'than just before lunch, when they were feeling hungry.

'Having to make decisions all morning is mentally taxing.

'And the judges were suffering from what's known as ego depletion.'

Their brains were running low on energy and that especially affects

the prefrontal cortex, which is involved in decision-making.

Traditionally, we assume humans are rational decision-makers.

They take in information, process it and come up with the best answer.

But real humans, even judges, don't operate that way.

They're biological creatures.

'The court system sets out to be rational and balanced,

'so it's a disturbing thought that it can be hijacked

'by the basic chemistry of our bodies.

'Even judges can be imprisoned by their biology.'

The story's the same with some of life's other big choices.

Where the decisions we make aren't necessarily conscious ones.

Instead, we're tugged along by hidden biological forces.

Evolutionary psychologist Geoffrey Miller has come up with

an interesting way to show this.

His team recruited the help of 18 lap dancers in New Mexico

and got them to record their earnings over three months.

We know that lap dancers' earnings fluctuate a lot.

Some nights, they earn 800.

Other nights, they might earn only 150.

And they're very conscious of how much they earn.

So it seemed like an ideal set-up for being able to ask them,

"How much have you earned night by night, shift by shift?"

And to be able to track that in relation to

where they are in the menstrual cycle.

Miller wanted to know if a woman becomes more attractive

to a man when she's ovulating.

At that point in her cycle, when she's most fertile,

a surge of the hormone oestrogen makes her skin softer,

her features more symmetrical

and her hip-to-waist ratio larger.

The changes are subtle,

but men's brains pick up on those cues unconsciously.

The results were surprisingly strong.

When women are ovulating,

they're earning about twice as much as they were earning

when they were menstruating,

but they were also earning a lot more than before menstruation.

So the real pattern is, if you're ovulating,

you're a lot more attractive to men, you're earning higher tips,

you're getting called over for more lap dances.

And we thought that was a pretty cool way of quantifying

female attractiveness to males.

Your hidden biological drives help you to select a partner.

But what makes you choose to stay with a partner?

It must have something to do with your values and your morals, right?

Actually, your hormones are doing a lot of the deciding for you.

One of them is this. It's called oxytocin.

Sometimes called the love hormone,

oxytocin strengthens the bonds we feel when we're in a relationship.

In a recent study,

heterosexual men who were in love were given a dose of oxytocin.

They were then asked to rate the attractiveness of different women.

The men who were given oxytocin

found their partners to be more attractive, but not other women.

In fact, with other women,

they kept a slightly greater physical distance.

So an attractive woman walks into the bar.

Lots of men clock her arrival.

But not this guy.

He's in love with his partner

and, pumped up with oxytocin, his attention doesn't wander.

From an evolutionary perspective,

you might expect that you don't want monogamy,

you want to have as many offspring as possible.

So, why do we have chemicals in the brain that enhance bonding?

Well, for the survival of the children,

having two parents around is better than having one.

It's so important that our brains make this decision for us.

In fact, the evidence suggests that some of our most complex decisions,

the ones we like to think of as carefully thought out,

are pre-programmed, influenced by our DNA.

Almost no choice at all.

If you feel the least bit uncomfortable, squeeze the squeeze ball

and we'll stop and take you out.

Read Montague uses neuroscience to analyse and predict voting patterns.

CHEERING AND APPLAUSE

It turns out that political ideology has strong biological underpinnings

which you can inherit from your parents.

Montague has found a link between a person's politics

and one basic reaction, disgust.

He has volunteers go into an MRI scanner,

where they look at a series of images.

I show them somebody with a knife to somebody else's throat,

physically threatening stimulus. A dead corpse.

Something that was gross, like flies on a salad,

or something like this.

These things elicit responses in your nervous system

and we record their brain activity.

Then we asked them, and not everybody agrees,

we asked them, "Hey, we have this other experiment we want you to do".

And they go into a booth and they answer a political ideology survey.

How do you feel about gun control,

abortion, premarital sex, things like that.

Montague's results are striking.

The greater the disgust response in the brain,

the more conservative the person is likely to be.

A smaller response correlates with a more liberal outlook.

The link between your neural response

and your political affiliation is not conscious, but it's powerful.

I think if you ask nine out of ten people on the street,

"How did you decide to vote for Candidate X?"

They would give you a long narrative about what they cared about,

the issues that Candidate X supported,

which side of those issues you were on

and how that person represented them.

But that is only half the story.

The shocking part is that your response

to a single disgusting image

can predict your score on that test

with 95% accuracy.

That kind of prediction is uncanny.

I show you a disgusting image,

I know how you're going to vote in 2016.

We may refine our political arguments,

they may become more sophisticated,

but the decision about our basic persuasion, that's already made.

'So far, we've been looking at decisions in the here and now.

'What soup do I want?

'Do I pull the lever?

'Who do I vote for?'

Orange. Green.

'But there's another aspect to the story of decisions.

'Predictions about the future.

'We have to weigh different options

'and guess how things might turn out

'at a time that doesn't yet exist.

'How does your brain pull off that trick?'

I have one hour of free time today and I'm trying to decide what to do.

I know I have to get to the grocery store, on the other hand,

I need to get to a coffee shop to work on a grant deadline.

And I'd like to be able to play with my son at the park today.

So, how do I decide?

Well, ideally, I'd like to be able to know what each of these

possible futures would be like, but I can't time-travel.

Or can I?

'It may sound like the plot of a movie, but wouldn't it be great

'if we could make decisions by looking back from the future?

'That's exactly what our brains are trying to do all the time.

'Running simulations of the future

'and giving each of them a different value.'

Think of valuations like neural price tags that tell us

how much we think something's going to be worth.

So going grocery shopping will put food in my fridge,

but, say that's worth ten units to me.

Writing a grant will fund my lab,

but it's difficult, let's say that's 25 units.

I love spending time with my son at the park,

so let's say that's 50 units.

Here's the thing - those prices can change through time.

If we get there, we run into friends and it's better than expected,

that ups my price tag for the next time around.

If we get there and the swings are broken and it's raining,

that lowers my price tag for the next time.

And that's important.

That's what allows us to prioritise how we make our decisions

based on the brain's best guesses for the future.

And it turns out there's a tiny, ancient system in the brain

whose whole job is to keep updating our assessments of the world.

I'm talking about the dopamine system.

The chemical dopamine typically has a constant rate of release.

But when something turns out better than expected,

there's a burst of dopamine.

That tells other parts of the brain

they should increase the value of that option.

When something is worse than expected, the dopamine drops

and the value goes down.

In most of us, this system works pretty well,

but it's delicately balanced.

Too much dopamine and that loop of positive feedback

gets out of control.

This is the root of addiction.

Neural psychiatrist Valerie Voon studies addictive behaviour.

She's interested in patients with Parkinson's disease.

They're producing less dopamine than normal,

so they're routinely put on medication to raise their levels.

What happens with dopamine medications that the patient

with Parkinson's is on is that it can potentially hijack the system.

Patients who were previously moderate in their behaviour

suddenly develop addictions to gambling, or food, or sex.

These dopamine-stimulating drugs are overstimulating the regions

involved in reward and motivation.

You see the cue and your expectation of the reward

becomes much larger than it should be.

When you take the medication away, they're always a bit dumbfounded

about how they ended up acting the way they did.

'As long as there's nothing wrong with our dopamine systems,

'it should be straightforward for us to control our impulses, right?

'Don't be so sure.

'Take the subprime mortgage meltdown of 2007.

'Between bankers hunting a quick profit

'and borrowers hunting their too-good-to-be-true dream homes,

'it turned into a storm of disastrous decisions.

'As a neuroscientist, what fascinates me

'is how everyone involved gave less weight to future consequences

'and were instead seduced by what was right in front of them.'

The very low interest rates plugged right into the

"I want it now" circuitry.

The idea is, take this house right now,

live better than you thought you could.

At some point in the future, the interest rates will go up,

but that's a long way away.

Because the pull of the now is so hard to resist,

the world economy almost tanked.

This present moment is a rich,

multisensory experience that's hitting me right now.

But the future, that's just an idea.

That's a simulation that takes place in my neural circuits

and it's a pale shadow compared to immediate experience.

It has less emotional pull than whatever is right in front of me.

So, once again, the brain is in conflict.

Different networks are battling it out between the present

and the future.

Instant gratification?

Or long-term reward?

When faced with these sorts of decisions, what do we do?

We rely on our willpower.

Think of willpower as that thing that allows you to pass on that cookie,

or at least the second cookie!

Or the thing that allows you to hit that deadline even though you want to be out in the sunshine.

We all know what it's like to have strong willpower and we also

know what it feels like when you just don't have enough of it.

In one experiment, people watch a wildlife film about animals in distress.

Half the audience has been told to react normally,

to cry if they feel like it.

The other half are instructed to curb their emotions,

using their willpower to squelch their feelings.

The key is what happens next.

After the movie, participants were given one of these - a hand exerciser -

and they were asked to squeeze it as long as they could.

The people who curbed their emotions give up squeezing sooner than the others.

They've exerted so much mental effort not to cry,

they actually have reduced physical strength.

This kind of self control, it takes energy.

It turns out that resisting temptation, or making hard decisions

or taking initiative - all of these draw from the same well of energy.

So, willpower isn't something that we exercise,

it's something that we use up.

It's like a tank of gas.

So, there's a good reason why we can't always rely on our willpower

to make us stand by our decisions.

Our willpower might be running on empty.

We all know that it's hard to get ourselves to do certain things,

like going to the gym.

I want to be in shape, but when it comes down to it,

there's usually something going on right in front of me that's more enjoyable.

So, the pull of what's happening right then

is more powerful than the abstract future notion of fitness.

So, to make certain that I come here,

I take inspiration from a man who lived 3,000 years ago.

In classical mythology, the hero Ulysses lashed himself to the

mast of his ship so that he could hear the bewitching song

of the sirens without steering into the rocks.

Ulysses knew that his future self wasn't going to be in any

position to make a good decision.

So, he structured things so that he couldn't do the wrong thing.

This sort of deal that's struck between your present

and your future self is known as the Ulysses contract.

My own Ulysses contract is to arrange with a friend to meet me here

at the gym, and that way the social pressure lashes me to the mast.

My friendship is collateral in the deal that I'm making with my future self.

This allows me to be the person I want to be,

making good decisions, resisting the seductive power of now.

-Come on.

-I got it.

Oh, yeah. Nice.

Our prisons are full of people who struggle with this.

They're unable to lash themselves to any mast

to avoid the rocks.

Attention, there is a door alarm.

For seven out of ten prisoners jailed in the US,

their ability to make long-term decisions is compromised.

They are there because of drugs.

For four decades, we have waged a war on drugs.

The US invests 20 billion each year into this fight.

But there's no sign of victory.

'And destroying the crop before the opium could be harvested from it.'

The difficulty with drug supply is that it's like a water balloon.

If you press it down in one place, it will come up somewhere else.

So, instead of attacking supply, a better strategy is to address demand -

and demand is in the brain of the addict.

So, if the problems lie in the brain, maybe the solutions do, too.

A couple of miles from my laboratory, there's a crack house.

It's abandoned now, but this was once a regular hang-out for Karen.

It brings tears to my eyes.

Because this was part of the lowest part I hit when I smoked crack.

And I can't believe that I was part of that crowd.

If you're not strong enough, you just can't handle it.

It kind of draws you in.

Karen has had an addiction to crack cocaine for many years.

I thought I was in control of everything.

But that was the drug. I mean, I wasn't in control of anything.

I was a mess.

Dirty, hair matted up, clothes looked like they were in a mud fight -

I couldn't believe it. And then I'd step back and think,

"Damn! How did I drop so low?"

Karen's story makes her an ideal candidate for a new programme

we're running in my laboratory.

Rather than simply forcing drug addicts to go cold turkey,

we're trying to treat them with neuroscience.

Getting the brain to take control of its own addiction.

Inside the MRI machine, Karen watches images of drug use

and drug paraphernalia.

We ask her to go ahead and feel her cravings.

We measured the networks in her brain associated with that craving.

Then we switch and ask her to suppress the craving.

OK, Karen, when you're thinking about suppressing your craving,

think about the costs this has had to you - in terms of money,

in terms of relationship, in terms of employment opportunities.

'OK.'

We show her the same images and measure the regions in her brain

that are active when she's trying to resist the desire to use.

These are the networks that become active in Karen's brain when she's craving cocaine,

and when she thinks about all the reasons to resist it, then these networks come online here.

And these networks, the craving and the suppressing,

are always locked in battle.

Here's the key - we now superimpose a gauge,

which tells Karen how the battle is going.

Her job is to move it by tipping the balance

of the suppressing over the craving.

They show you pictures of different things. You have to do suppress and then not suppress.

It was like a little meter.

When it got to the first time, I couldn't do it at all.

Then, the second time, I got wind of it and I could really concentrate and say,

"Hey, this is it! This is what I've been missing.

"Your brain is the one that told you you needed crack,

"so why can't you train your brain to tell you it's not time for crack?"

I mean, I can suppress other things, why can't I suppress crack?

At the moment, she's looking at this background picture of cocaine

and she is working her way over to suppressing that craving

and holding it there successfully.

Now, the idea is that she can practice this in the scanner and learn how to get better at it

and the key is when she's back out in the real world and somebody offers her crack cocaine,

she'll have the tools available to know how to resist.

I'm not going to say I'm cured, because how can you be cured

of something that your brain conjures up - your subconscious conjures up.

So, I take steps to, when the thought goes through, I push it out.

I suppress it.

You know, I'm not going to say three months from now, a year from now, I'll be clean,

but that's what I work towards daily.

For me, Karen offers a glimpse of how neuroscience

can help people with addiction.

She's rewiring her circuitry, she's shaping her brain

to be better aligned with who she would like to be.

The future is filled with promise.

I'm married, I have a great husband, I have a great life

and I don't want to jeopardise that just for a hit of crack.

So, I mean, it's even more of a reason why I quit crack.

It helps my suppression state, because I can actually stop

and I'm doing it for myself, but I'm doing it for others.

My husband, my dogs, my family and that's what's important to me.

Karen has hope for resolving the conflict that constantly rages

in the hidden world of her neural networks.

I think a biological approach stands a better chance

of working than mass incarceration.

As we learn more about our own brains,

we can break away from slavery to our impulses

and earn the freedom that comes with having greater choice.

Decision-making lies at the heart of everything -

who we are, what we do, how we perceive the world.

Without the ability to decide,

we would be stuck in limbo between conflicting desires.

We wouldn't be able to navigate the now or plan for the future.

Neuroscience shows that you are not an individual,

you're made up of multiple competing drives.

And by understanding how choices battle it out in the brain,

we can learn how to make better decisions for ourselves and for society.

CROWD CHEERS AND APPLAUDS

Next time on The Brain, I'm going to investigate how our brains

are fundamentally wired to work together.

How this social network that envelops us from birth

is vital for our survival.

Understanding how brains deal with each other

allows us to understand what bonds our species...

..driving us to help one another.

And what makes us hate.

What allows acts of human violence.

Here, in 1995, thousands of Bosniaks took refuge

inside this United Nations compound.

But then on July 11th, the UN commanders made the decision

to expel all the refugees and they delivered them right into the hands

of their enemies who were waiting just outside this gate.

Even the most basic encounter...

like getting a cup of coffee...

..relies on trust with a stranger.

-Can I get a latte, please?

-Definitely.

-Thanks.

Our lives are built on these intersections.

It helps us to make sense of our past

and holds the key to our future.