Original subtitles

Over the last 100,000 years,

our species has been on quite a ride.

We've gone from primitive hunter-gatherers

poking around for scraps

to a world-conquering, city-dwelling,

hyperconnected super species,

and it's all thanks to the 3 pounds

of wet biological material stored up here.

We live surrounded by our inventions.

We have the means to travel,

to make,

to communicate,

to build.

What I find incredible is that all of this

was built with the same neural material

that our ancestors used to hunt and to build primitive tools.

The genius of mother nature and the secret to her success

was to build a brain that could innovate to make the journey

from primitive man to this in a very short amount of time.

I want to explore what it is about the brain

that's made this journey possible.

If we can understand how it works,

then maybe we can direct its power in new ways

and open a new chapter in the human story.

So what's next for our brains?

What do the next 1,000 years have in store for us,

and in the far future,

what is the human race going to look like?

What will we be capable of?

This is a journey into who we might become.

We'll look at how we can use our brains

to control new kinds of bodies...

How our sensory experience can be expanded to new horizons.

We'll look at how we might one day

separate our minds from our physical selves,

even possibly overcome death.

The human body...

It's a masterpiece of complexity and beauty.

It's a symphony of 40 trillion cells,

all operating in concert,

and it's all orchestrated

by the 3-pound organ we call the brain.

Sensory information floods in.

Decisions are made.

Responses are formulated.

The brain sends out commands,

and the body moves into action,

but what if the brain could do more, handle more?

What if there were other ways for it to operate?

We're heading for a fundamental change

in the relationship between the body, the brain,

and the outside world.

We're marrying our biology with our technology,

and that's poised to transform who we will be.

This is all possible, thanks to a special property

of the brain called plasticity.

It's best illustrated through a remarkable story.

Meet Cameron mott.

In this home movie, she's 4 years old.

♪ I'm a Princess girl all day ♪

♪ a Princess girl, prin... ♪

I'm a Princess girl.

Eagleman, voice-over: One day, Cameron

suddenly started having seizures.

Oh! Ooh...

Woman, voice-over: The really big issue was that

Cameron's seizures were drop seizures where she would

fall down to the floor very quickly,

and they were very aggressive.

Cameron? Oh!

Whoopsy.

Eagleman, voice-over: She was diagnosed

with rasmussen's syndrome,

an inflammatory disease that attacks the brain.

It causes paralysis and, ultimately, death.

To save Cameron's life,

her physicians proposed a radical solution.

They would remove the diseased part of her brain.

Little harder.

Man, voice-over: The procedure itself is probably

the most drastic surgical procedure

that can be done in neurosurgery.

You know, it's not a simple operation.

There are man...

On a scale of 1 to 10,

10 being one of the more difficult operations

that we would typically perform in neurosurgery,

I'd say it's a 10.

Eagleman, voice-over: Seeing no other option,

Cameron's parents consented.

The real risk in the surgery is not

what happens if we do the surgery.

The question is, what happens to this person

if we don't do the surgery?

Eagleman, voice-over: The issue was that an entire half

of Cameron's brain had been affected.

Woman, voice-over: Our biggest concern was, would she survive?

Would there be some complication?

Um, would we go through all of this

and then still have seizures at the end?

This is Cameron's preoperative scan.

This is the material that underpins her intellect

and her emotion and her sense of humor,

who she is.

In this scan, the empty space

is where half of her brain has been removed.

No one could be sure how the loss

of that much brain tissue would affect Cameron.

What would she lose?

Could she be like other children?

This is Cameron 7 years on.

She's seizure-free...

And, more importantly,

beyond a slight weakness on one side,

she betrays no sign of the ordeal

that she went through.

I like to run a lot

and do different types of stuff outside.

I love math.

Give me... give me 3 quizzes to do, and I'll do it.

Ok. Let it go.

Just imagine taking your laptop and tearing out

half the motherboard and expecting it still to function.

It would never work with a computer,

but it can work with a young brain...

And that has dramatic implications.

We used to think of the brain as a fixed system

with different parts dedicated to specific jobs,

like seeing or deciding or moving,

but no region works in isolation.

The brain is a vast, dynamic, interconnected network

that's always changing.

Instead of hardwired, I like to think of the brain

as live-wired, and that flexibility of the brain

opens up new possibilities for our future.

It could be argued that this future has been with us

since the 1970s in the form of a simple piece of technology.

This is a cochlear implant,

and it can give hearing to deaf people.

It picks up sounds and converts them to electrical signals

that plug directly into the cells of the inner ear.

Now, when it was first introduced,

researchers didn't think it was going to work

because biology is wired up with such precision

and specificity and this just takes

crude signals and shoves them into the brain

in a way that the brain's not expecting.

The cochlear implant represents a marriage

between metal electrodes and biological cells,

and yet it works.

Around the world, almost a quarter-million people

have had the chance to hear for the first time,

thanks to these implants.

Wow. Ha ha ha!

Eagleman, voice-over: Here's how.

Whether it comes from your ears or your eyes

or a touch on your skin, all the information

that enters your brain is converted into the same stuff...

Electrochemical signals.

These are the common currency of the brain.

When the implant produces these signals, however crudely,

the brain finds a way to make sense of them.

It hunts for patterns...

Cross-referencing with other senses.

At first, the signals are unintelligible,

but soon, meaning emerges.

Cochlear implants reveal something amazing

about the brain, which is, whatever signals you feed

into it, the brain will figure out

how to extract something useful out of that.

As long as the data coming in has a structure

that maps onto the outside world,

the brain will figure out how to decode it,

and this turns out to be one of nature's greatest tricks,

and now that we know about it,

it opens up a world of possibilities.

Why restrict ourselves to trying to replace

lost or damaged senses?

There must be ways for us to enhance

or add to the senses that we already have.

In my laboratory, we've created this vest.

It turns sound into patterns of vibration

that are felt on the skin of the torso.

The idea is that, given enough time,

the wearer's brain will learn

to automatically decode these vibrations.

They'll instinctively feel and understand information.

This is the alien language game,

so you're gonna feel a word presented to you

as a pattern of vibration on your torso.

Through time, you're going to get

better and better at this as your brain

starts decoding how these inputs maps onto words

that you know, and your job

is just to figure out what the language

of the vest is.

I can feel the vibrations on my body.

It makes no sense to me. They're just random.

I'm aware that maybe one in the left shoulder,

right shoulder, lower back...

Eagleman, voice-over: One of my lab members, Joshua,

wore the vest as he went about his day.

An app sends a pattern of vibrations to his torso.

He guesses what word that pattern represents,

and he's told whether he's right or wrong.

Joshua, voice-over: For the first week or so,

I mean, it's just total nonsense

to try to figure out which word was just projected onto me,

but as time has gone by, I am able to,

through some process, distinguish them.

Eagleman, voice-over: It seems strange that you could

understand information through your torso,

but that's the surprise.

It doesn't matter how signals find their way to the brain.

We have these peripheral senses that we plug in,

but here's the thing.

Our eyes, our nose, our mouth...

These are just what we inherit from our evolutionary past.

It's what we come to the table with,

but we don't have to stick with it

because it might be possible that we could plug

some sensory channel into an unusual port into the brain

and the brain will just figure it out,

and it may be that in the near future,

we can invent new sorts of sensory devices

and plug them directly into the brain.

In theory, there's no limit

to the new sensory expansion that we can create.

So just imagine if we could feed in an input

of real-time weather data so you could feel

if it's raining 100 miles away

or if it's gonna snow tomorrow...

Or imagine feeding in real-time stock data

and developing an intuitive sense

of how the markets were moving.

You'd be plugged into the global economy.

Because of the brain's capacity to take on new inputs,

we should be able to expand the experience of being human.

We could enjoy things that wouldn't be possible

with the traditional senses we arrive with.

It may be that the evolution of our technology,

rather than our biology,

is what guides the journey of our species from here on out.

As we move into the future,

we'll increasingly design our own portals on the world.

As far as we can tell,

there's no limit in what the brain can incorporate.

Instead, we now have the tools to shape

our own sensory experiences,

to widen our small windows on reality.

Eagleman, voice-over: Now, how we sense the world,

that's only half the story.

The other half is how we interact with it.

What if we could use the brain's flexibility

to change our physical bodies?

This is jan scheuermann.

Because of a rare genetic disease,

the spinal cord nerves that connect her brain

to her muscles have deteriorated.

Scheuermann, voice-over: I can't move anything below my neck.

Where the stem of my brain meets my spinal cord,

there's some deterioration there,

and the signals aren't getting through,

so my brain is saying, "lift up," to my arm,

and my arm's saying, "I can't hear you."

Eagleman, voice-over: Now jan's participating

in a trailblazing experiment...

Part neurosurgery, part robotics.

Two electrode arrays implanted into her brain

provide a link from her motor cortex to this...

The world's most advanced robotic arm.

Ok. Up, down.

Eagleman, voice-over: Its fingers can curl and uncurl.

It can roll. The wrist can flex.

Jan can control it just by thinking about it.

Right...

And grasp.

Eagleman, voice-over: Though she speaks the commands out loud,

she has no need to.

There's a direct physical link between the arm and her brain.

Down.

Eagleman, voice-over: An arm normally moves

because of a storm of activity in the motor cortex.

From there, the signals travel down the spinal cord

to the muscles of the arm.

In jan's case, electrodes eavesdrop

on the cortical signals directly

and redirect those to Hector, her new arm.

Scheuermann, voice-over: Like riding a bicycle,

the brain doesn't forget how to move the arm,

even though it hasn't moved in... in 10 years.

Eagleman, voice-over: With practice, this relationship

will become fully unconscious.

She'll be able to move Hector automatically

without thinking about it,

just as we do with our biological limbs.

Oh, it feels very good to be able to shake hands

and fist-bump and interact.

It's so very life-affirming to me to be able

to reach out and touch a person.

Eagleman, voice-over: Jan's experience points to a future

in which we use technology to enhance and extend our bodies,

not only replacing limbs or organs,

but improving them, elevating them

from human fragility to indestructibility.

Hollywood has often imagined a person who's part machine.

Well, that fantasy is fast becoming real.

As we learn how to take on new sensory experiences

and control new kinds of bodies, that's going

to profoundly change who we are as individuals,

and that's because our physicality sets the tone

for how we feel and how we think and who we are.

At this moment in history, it may be that we have

more in common with our stone-age ancestors

than we do with our descendants in the near future.

We're already beginning to extend the human body,

but no matter how much we enhance ourselves,

there's something we need to keep in mind.

Our body is made of flesh and bones.

It's going to deteriorate and die,

but what if the study of the brain

could address our mortality?

What if in the future, we didn't have to die?

There will come a moment when all of your neural activity

will come to a halt, and then the glorious experience

of being conscious will come to an end,

and it doesn't matter who you know or what you do.

It's the fate of all of us.

It's the fate of all life, but only humans

are so unusually intelligent

that we suffer over this.

When someone dies,

those who are left grieve.

They mourn the lost relationship,

but with every death, there's another loss.

Every brain contains a lifetime of information,

experiences, knowledge, wisdom.

At the moment of death, all that becomes lost.

Francis crick was one of the discoverers

of the structure of DNA, and he was also a friend

and a mentor to me, and when he died,

I remembered thinking about what a waste it was

that he was cremated and this brain of one of the greats

of 20th-century biology was going up in flames

because even after a person dies,

there's a lot of information about them stored

in the physical structure of their brain,

and we're reaching a point in neuroscience

where it becomes a possibility that we could preserve a brain

and read out the information and live with that person again.

Brain preservation is a new field.

It's controversial, and its promise is still unproven.

Nonetheless, some people

are actively exploring the possibility.

Here in the Arizona desert, the researchers

at the alcor life extension foundation believe

they can give the dead a chance to live again.

This facility holds the remains of over 100 people

preserved at ultralow temperature.

It's run by Max more,

who describes himself as a futurologist.

As soon as legal death has been declared...

Which is really not biological death,

but we have to wait for that point legally...

We can then move the patient

from the bed into the ice bath.

We can add external ice on top.

We restart respiration.

We restart circulation by doing, essentially, mechanical cpr,

and then we also administer 16 different medications

to try and protect the cells as we cool down.

Eagleman, voice-over: Each body is submerged in liquid nitrogen,

bringing its temperature below minus-300 degrees.

This process is known as cryonic suspension,

and it doesn't require a whole body.

Sometimes a client chooses to preserve

only their head and brain.

So what we'll do is, we'll do the neuroseparation

somewhere down here, a few vertebras down.

We'll move the patient's cephalon

into the cephalon ring, where the head

is essentially upside down so we can excess the carotids,

and... just like with the whole-body procedure,

except there, we go through the chest...

Here, we're washing out the blood

and body fluids uh, from the brain.

Eagleman, voice-over: The idea is to perfectly preserve a body

into the distant future

with the hope that an advanced technology

not yet invented will allow for thawing and reanimation.

So, Max, tell me about these dewars.

All our patients are stored in these.

We call this a bigfoot dewar.

Uh, it contains 4 whole-body patient,

as you can see from this 3D-printed model.

Each of those goes in aluminum pod

that gives extra protection,

and we also get 5 neuropatients

in the center column,

so these fill up with about 450 gallons

of liquid nitrogen.

Uh, they're not sealed.

We just have a cap

floating on the top, and we top these up

once a week with liquid nitrogen

to keep them full.

So there are 9 people in here?

Not in every one.

Depends on how many neuropatients we have.

Uh, there's actually room for more neuropatients,

so some of them have neuropatients.

Others don't, so between 4 and 9.

Eagleman, voice-over: Alcor began 50 years ago.

Currently it houses 129 frozen residents,

and that number continues to grow.

Some of the pictures say,

"first life cycle... 1927 to 1996."

Do you see it as being a second life cycle?

What we're doing is, we're really just

giving people another chance at life.

Just as if today you were, you know, in your 30s

or 40s, had a heart attack and we did some

experimental surgery and brought you back,

you might have several decades more,

but we're talking something a little bit more radical.

We're talking about not just for another 80 years,

but potentially thousands of years, maybe longer.

Eagleman, voice-over: The people in these dewars

have taken a leap of faith into an unknown future.

There's no guarantee that the technology will ever come along

that allows them to wake up again...

So perhaps there are other ways

to access the information stored in a brain

not by bringing a deceased person back to life,

but by finding a way to read out the data directly.

This is both a promising idea and a monumental challenge.

At the department of brain and cognitive sciences at mit,

Sebastian seung is among the first pioneers of that process.

He's attempting to map out the innumerable connections

that underlie a brain's function.

That unimaginably vast network of pathways and links

is called the connectome.

Your connectome is unique.

It's one of the deepest theories in neuroscience

that your memories are stored

in your unique pattern of connections.

I like to think of it as a theory of personal identity,

what makes you you.

Eagleman, voice-over: The average human brain

has 86 billion neurons

and thousands of trillions of synaptic connections.

When the connectome is fully worked out,

it will be the most complex wiring diagram ever created.

It's very difficult

to map out connectivity inside the brain.

There's only one technology right now which promises

to give us all the connections from a single piece of brain,

and that's called serial electron microscopy.

Eagleman, voice-over: Seung is beginning

by mapping a mouse brain.

The process starts with taking a piece of brain tissue

and slicing it.

It's a high-tech deli slicer

for cutting very thin slices of brain.

To cut really thin,

you have to have a very sharp knife.

This is the world's sharpest knife,

a diamond knife whose blade is honed to atomic sharpness.

You can see a metal part which is moving up and down.

A piece of brain is mounted on it,

and the brain is being moved back and forth against a blade,

so slice after slice of brain

are floating onto the surface of water.

Each slice pushes the previous slice forward.

In order to see this cutting process,

a microscope is mounted on top of the ultramicrotome,

and it projects an image onto this computer screen,

where we see the cutting happening.

This conveyor belt produces a tape,

a very long tape which is kind of like a movie,

every frame of which is a slice of brain.

Eagleman, voice-over: Once the brain has been arranged

in these filmlike strips, each sample is subdivided

into tiny areas which are then scanned

by a powerful electron microscope.

That process produces this...

A segment of brain magnified 100,000 times.

At this resolution,

it's possible to see almost every feature.

These small, black dots are DNA inside an individual cell.

The next step is to compile these images.

By stacking them in the thousands,

one on top of each other,

and then tracking the neurons through each image,

it's possible to reconstruct the exact way

that the neurons are connected,

a 3-dimensional model of the connectivity.

It should be possible to do this with whole human brain someday.

The result would be a map of all the wiring

that underpins a person's thoughts,

experiences, and beliefs.

There's just one issue.

If you image an entire human brain

with this resolution,

it would be a zettabyte of information.

Sounds like a dirty word, "zettabyte."

You never heard it before.

It's never spoken in polite company.

Well, it's the...

It's the total digital content of the world right now.

That's, uh, how much information it would be.

Eagleman, voice-over: It's a daunting figure.

Does it mean that the idea of reading out a human brain

will always remain beyond our reach?

Well, experience says that computing power alone

shouldn't be a barrier for too much longer.

There's a common observation in computing called Moore's law.

It states that processing power doubles every two years.

If that doesn't sound like much, think of it this way.

It means that computers today are a million times

more powerful than they were in the 1970s.

Just 20 years ago, this supercomputer behind me

was equivalent to all the computing power on the planet.

20 years from now, it'll probably be considered

a modest force of the type

you might shrink down and wear on your body.

We're in an era now where we're developing technologies

that can store unimaginable amounts of data

and run gargantuan simulations, and this is where our biology

is on a crash course with our technology.

So let's say the time will come

when computer power isn't an issue.

That opens up a new realm of possibility.

Suppose we could make a digital copy of the brain.

Then not only we could read it out.

We could make it run.

In the same way that computer software can run

on different hardware, it may be that the software of the mind

can run on other platforms.

In other words, what if there's nothing special

about the biological neurons themselves

and instead, it's only how they connect and interact

that makes a person who they are.

If that proved to be correct, it would follow

that we can exist digitally by running ourselves

as a simulation, and this is what's known

as the computational hypothesis of the brain.

The idea is that the wet, biological, gushy stuff

isn't the important part.

What matters are the computations

that are running on top.

The idea is that the mind is not what the brain is.

It's what the brain does.

In theory, you might swap cells for circuits,

oxygen for electricity.

The medium doesn't matter, provided all the pieces

and parts are connecting and interacting in the same way.

All your thoughts, emotions, memories,

your whole personality would still emerge.

There'd be no biological brain,

but there'd still be a fully functioning version of you.

This sounds like science fiction,

but a team in Switzerland has begun

an exceptionally ambitious project

that takes the first steps down this path.

They're attempting to build

a full working simulation of a brain.

It's called the blue brain project.

Sean hill is one of the members of the team.

What is the long-term goal here?

To deliver by 2023 a software and hardware

infrastructure capable of running

a whole human brain simulation.

If we want to move towards being able

to simulate an entire human brain,

how do we know what are

the important things to capture...

The structure, the cells, all the way down

to the proteins, the molecules?

How do we know?

We're working at subcellular.

We're working at cellular.

We're working at microcircuit.

We're working at brain regions

of mesocircuits,

and then we have whole brain

but for very simplified neurons,

so our goal is to get to whole brain

but with very detailed neurons.

Eagleman, voice-over: As a starting point,

they're looking at rat brains.

They take tiny slices of brain and subject them

to minute jolts of electrical current.

That mimics the activity of the living brain

and prompts the cells to interact.

Each interaction is recreated on the project's supercomputer

and then integrated into a larger model with data

from hundreds of other labs around the world.

The result is this electrical storm.

This is the best approximation

of what a very tiny fraction of your brain is doing

when you're, say, just staring into space.

The total activity in your brain is hundreds of millions of times

more than what you're seeing here,

and this typhoon of activity is roaring along

every second of your life.

We're not building abstract models.

We actually taking data from laboratories.

We're extracting, uh, probabilities.

We're extracting distributions from that

to build a much larger model that is based

on biological data,

not based on the assumption

of how... how biology works, but actually

on data that comes out of a biolaboratory.

Eagleman, voice-over: The blue brain team hopes

to achieve their goal by 2023...

A full working simulation of a human brain,

and that raises a question...

What will the finished product be?

Will it be a mind? Will it think?

Will it be self-aware?

If the answer is yes and a mind can live in a computer,

then do we have to copy nature's biological blueprints,

or might it be possible to program a different kind

of intelligence, one of our own invention?

People have been trying for a long time

to create machines that think.

This field, called artificial intelligence,

has been around since at least the 1950s.

The problem has turned out to be unexpectedly difficult,

and this speaks to the extraordinary enigma

of how the brain does what it does...

Because, while we'll soon have cars that drive themselves

and it's almost two decades since a computer

first beat a chess grand master,

the goal of a truly sentient machine

still waits to be achieved.

One of the latest attempts to create

an artificial intelligence can be found

at the university of Plymouth in england.

It's called icub.

It's a humanoid robot,

and it's designed to learn as a child learns.

Traditionally, robots are preprogrammed

with everything they need to know,

but what if you could create a robot

by developing it the way that a human infant grows?

Icub is about the size of a two-year-old.

It has eyes and ears and touch sensors,

and these allow it to interact with the world

and learn from it.

Babies don't come into the world knowing how to speak and walk,

but they come with curiosity,

and they pay attention, and they imitate.

They use the world that they're in as a textbook

so they can learn by example,

so what if you wanted to create a robot to do the same thing?

Well, you would take a crude brain simulation,

and you'd give it a mechanical body

so that it could interact with the world.

Hello.

Hello. I'm icub.

This is a red ball.

This is a red ball.

This is a yellow cup.

Yellow cup.

Eagleman, voice-over: The aim is that with each interaction,

the robot continually adds to its base of knowledge.

It's making connections

and building a repertoire of appropriate responses,

and, because it looks and sounds a bit like a human,

it's easy to be convinced that it thinks like one.

Where is the yellow cup?

Where is the red ball?

Eagleman, voice-over: Often, icub gets it wrong.

That's part of the process...

What is this?

I'm sorry. I don't know what this is.

Eagleman, voice-over: But the more it gets it wrong,

the more you get the sense

there's no real mind behind the program.

What is this?

I'm sorry. I don't know what this is.

Eagleman, voice-over: What becomes clear

is that icub is purely mechanical.

You can feel that it's run by lines of code

instead of trains of thought,

so it can say, "red ball,"

but does it really experience redness

or the concept of roundness?

Do computers do just what they're programmed to do,

or can it ever really have internal experience?

In the 1980s, the philosopher John searle

was chewing on this problem, and he came up

with a thought experiment that gets right at the heart of it,

and he called this the Chinese room.

Eagleman, voice-over: The experiment goes like this.

I'm locked in a room.

Outside, there's someone who only communicates in Chinese.

She writes out some questions

and then posts those to me in the room.

Now, I don't speak Chinese, but I do have these books,

and they give me instructions on exactly what to do

with these symbols, so I look in the book,

and... and if I can find a match to the symbols,

then the book tells me exactly how to respond,

so I can look up this response.

That matches, so now I can post this

as the reply to the message I received.

Eagleman, voice-over: When our Chinese speaker

receives the message, it makes perfect sense to her.

Eagleman, voice-over: As far as she's concerned,

we're having a conversation in her language.

Just by following a set of instructions,

I can convince somebody on the outside

that I speak Chinese,

and if I have a large enough set of response books,

I can have a conversation about anything,

but here's the important part.

I, the operator, do not understand Chinese.

I can manipulate symbols all day long,

but none of it has any meaning to me.

The argument goes that this

is just what happens inside a computer.

No matter how sentient it seems,

the computer is only ever following instructions,

manipulating symbols.

Now, not everybody agrees with this interpretation

of the Chinese room.

Some people point out that, although the operator

doesn't understand Chinese, the system as a whole,

the operator plus the books, does understand Chinese.

Whatever the correct interpretation,

the important thing is this.

It exposes the difficulty and the mystery

of how physical pieces and parts

ever come to equal

our experience of being alive in the world.

With every attempt to simulate or create subjective experience,

we're confronted with one of the greatest mysteries

of neuroscience.

Every brain cell is just a cell...

Running its basic operations, following its local rules.

How do billions of these add up to the feeling of me?

If we want to see how simple parts

can give rise to something bigger,

one can look to the natural world.

The Houston zoo is home

to a large colony of leaf cutter ants.

Individually, each ant behaves simplistically,

but when these ants work together,

the colony is like a super organism

that accomplishes something much greater.

All of these ants have a different job.

There are some that are really, really good

at just cutting leaves,

others that are good at carrying leaves,

and then others that do other functions

within the group.

They're independent, but they all work

towards a common cause,

so they're all coming out doing

what their job is to do for the good

of the whole colony.

So do these ants communicate by chemical signaling?

Yes. They do.

Whenever they find something that is,

you know, a great leaf for them to cut

or fruit or vegetables,

uh, when one ant goes and finds that,

they will lay that signal,

and then the rest will just follow it,

and it becomes a very straight line.

Instead of them branching out,

going different directions

to get to the same thing,

they all follow the... The chemical signal.

So what happens if one of these ants

is just off by himself?

So if we were to get this guy,

this is a bigger ant here.

Yeah. Poor guy. He's just... He's just running...

Going around in circles.

Spinning in circles. Yeah.

He's not getting that signal,

that chemical signal, back

that, "you are going in the right directions."

Eagleman, voice-over: This ant can't function

outside the network of local signals

because he needs those to tell him what do.

Put him back into the network,

and he does just what's needed to serve the greater purpose.

The scout ants only worry about where to find the best plants.

The leaf cutters do the cutting.

The carriers know which parts to bring back to the nest,

and there, inside, other ants build, tend, harvest, mate.

It's an entire system

regulated by local signaling between them.

In all of this, no one ant sees the big picture

about the agricultural society they've created,

and it doesn't matter.

The power of the colony emerges

from the local interactions between the ants.

Put enough ants together, and, bang,

you get a superorganism with sophisticated properties

that don't belong to any of the parts,

and this is the concept of emergent properties.

Put enough simple units together and have them interact

in the right ways, and something larger emerges.

The idea is that something like this happens in the brain.

A neuron has certain properties.

It can gather chemical and electrical signals

and spit out signals to other neurons,

but fundamentally, it's a cell,

like trillions of others in the human body.

It spends its life embedded in a network of other cells,

and, whatever its function,

all it does is react to local signals.

Just like the ant, a brain cell spends its life

running its local programs,

but get enough brain cells together

interacting in the right ways, and the mind emerges.

The concept of emergent properties offers a possible way

to understand how the vast neural populations of the brain

might produce consciousness, and it gives rise to a question...

Could consciousness emerge from anything

that has lots of interacting parts?

Could a city be conscious?

Or maybe it's not enough

to have lot of simple pieces interacting.

Maybe the parts need to interact in very specific ways.

If that's true, then we might expect to find

particular signatures of activity

in networks that are conscious.

At the university of Wisconsin, giulio tononi and his team

are hunting for those signatures.

They're focusing on the transition to consciousness

that happens in the brain every single day when we wake up.

Tononi, voice-over: When you wake up in the morning

from a dreamless sleep,

before, there was absolutely nothing,

and then you're awake,

and in the... the space of a few seconds,

there is everything...

Colors, sounds, people, thoughts, desires,

plans for the day, and, of course, the world around you.

That is consciousness.

Eagleman, voice-over: Tononi's experiments use tms,

transcranial magnetic stimulation,

to make small, targeted disruptions in brain activity,

and they can do this while a person is awake or asleep.

In the awake brain, an electrical pulse

moves outwards across the cortex like ripples on a pond,

but in the sleeping brain, only nearby areas react.

The ripples hardly spread.

Tononi, voice-over: When you fall into dreamless sleep,

somehow the neurons are not able to talk to each other.

What we activate with tms remains very local.

It remains there. It doesn't travel anymore.

Eagleman, voice-over: That spread of activity

across the waking brain may be a clue to consciousness.

While different regions of the brain are invested

in different tasks, consciousness seems to have

something to do with integrating activity

across vast brain territories,

linking areas to produce a single, unified experience.

Tononi, voice-over: You don't have an experience

split in two pieces.

When I see your shirt,

I don't see a shape and the color separated from each other.

They are together.

They are bound together, so every experience is one.

Eagleman, voice-over: Every moment of experience

is a composite created from innumerable possibilities.

I might be feeling the heat of the day.

I might be remembering an event from high school.

My stomach might be digesting lunch.

I'm also seeing. I'm hearing.

My brain will create my sense of self

from all these different strands.

How the strands are woven together is still a mystery,

but tononi believes that the key to consciousness

is contained in these patterns of interaction.

He also believes that this key

doesn't have to belong only to biological creatures.

That definitely is how it evolved,

and it takes an organization of that kind to do it.

It just needs to be made the right way.

Eagleman, voice-over: Building consciousness on another medium

is still squarely in the realm of speculation.

It could turn out that there's something special about neurons

so that only a biological brain could produce consciousness.

Nonetheless, this idea offers us a glimpse

of one possible future.

With powerful enough computers simulating all the interactions

of a human brain, we could one day become

nonbiological beings, and that would be

the greatest leap in the history of our species.

We could leave these bodies behind.

Digitally, you could live whatever life you wanted

wherever you wanted with a kind of immortality on offer.

While the stars are far beyond the reach

of any flesh-and-blood human lifespan,

you could be uploaded and sent off

to experience other solar systems...

Or you could enter an existence in a simulated world...

One in which you flew...

Or lived underwater

or lived a life of luxury.

Maybe you could journey into a reconstructed version

of the past.

When we imagine simulated life, the choices are endless,

and they include a strange possibility

that what we're talking about is something

that's happening already right now.

The simulation could look something like this,

and it could be that we're already in it.

Now, that idea might seem preposterous,

but it's surprisingly difficult to disprove.

It seems hard to imagine that all of this

could be a simulation, but we already know

how easily we can be fooled.

Every night when you go to sleep,

you have bizarre dreams, and when you're there,

you believe those worlds entirely.

The fact that you can be so fooled by your dreams

is sufficient reason to question

what you're experiencing right now.

The philosopher Rene descartes wondered, "how can we ever know

whether what we're experiencing is reality?"

He said, "how do I know I'm not just a brain in a vat

"that's being stimulated in just the right ways

"so that I believe that I'm touching the ground

and seeing people and hearing their voices?"

And he realized there's no way to know,

but he realized something else, that there's some me

at the center of all this trying to figure this out,

so even if I am a brain in a simulation,

I'm thinking about it,

and, therefore, I am.

Over the course of this series,

we've discovered just how complex

and remarkable the human brain is,

how reality is something constructed inside our heads,

how we're built to need others...

How so much of who we are and what we chose to do

is governed by factors outside our conscious minds.

Now it seems to me that we stand at a major turning point,

one where we might take control of our own development.

We face a future of uncharted possibilities

in which our relationship with our own body,

our relationship with the world,

the very basic nature of who we are

is set to be transformed.

For thousands of generations,

humans have lived the same life cycle over and over.

We're born. We control a fragile body.

We experience a limited reality, and we die,

but science and technology are giving us tools

to transcend that evolutionary story.

Our brains don't have to remain as we've inherited them.

We're capable of extending our reality,

of inhabiting new bodies,

and possibly shedding our physical forms altogether.

Our species is just at the beginning of something,

and we're discovering the tools to shape our own destiny.

Who we become is up to us.

"The brain with David eagleman"

"the brain with David eagleman"

is available on DVD.

The companion book is

also available.

To order, visit shoppbs. Org

or call 1-800-play-pbs.