Nova (1974–…): Season 43, Episode 6 - Memory Hackers - full transcript

Memory is the glue that binds our mental lives. But how does it work? Neuroscientists using cutting-edge techniques are exploring the precise molecular mechanisms of memory. By studying a range of individuals ranging-from an 11-ye...

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Memory... it's the key
to our identity.

Without memory, we're nothing.

It's who we are.

But how does it actually work?

It's a huge mystery.

Today, scientists
are probing our brains

like never before.

We're seeing a memory being
formed in front of your eyes.

Finding clues that lead us
to shocking new places.

Your memory's not as accurate
as you think it is.

We can tinker with a specific
memory at will.



Perhaps Mother Nature

needs a little bit of tweaking
on the dial.

From editing memories...

We can implant a false memory.

To deleting our worst fears.

It was unbelievable.

I was standing there like,
"How can this be possible?

I used to be terrified
of spiders."

We target and even erase
the fear memory itself.

Are we approaching the day where
at the flick of a switch,

we can rewrite our past?

Being able to use new
technologies to edit memories

is frightening.

I think that it's a matter
of when this happens,



not a matter of if it'll happen.

"Memory Hackers,"
right now on NOVA.

I remember...

I remember...

I remember...

I remember...

Hmm...

Memory.

We know it as a record
of our lives:

how to find our keys
or recite facts from school.

But stop and think about it.

It's so much more.

From your earliest memory...

Falling off of a horse
at about five years old.

When I walked into kindergarten
and I met my best friend.

About 1925, we moved
to 513 Spring Avenue.

Your happiest...

When my daughter was born.

When she, like, came out.

Seeing a real life human being

breathe that first breath
of fresh air.

Or saddest...

The death of my father.

We are little
but the sum of our memories.

It's who we are.

That's how we understand
ourselves and our lives.

Consider for a moment
just how vivid a memory can be.

The smells, the sounds...

I know the shoes, the socks,
the pants and shirt I wore.

It was like it happened
yesterday.

I do have a picture in my head.

I can see it!

That is a remarkably complex
computational process

that memory achieved

within milliseconds.

What an incredible,
powerful gift.

How is this gift possible?

How does the world
get into our heads

and turn into a memory?

How does memory actually work?

Wow.

Turns out that's one
of the biggest mysteries

in science today.

If you go and ask most people,

they would say
they understand memory,

but the truth is really
rather far from that.

We sort of understand
the tip of the iceberg.

We're just kind of
nibbling around

the big central mystery
of memory:

how do I bring back in time now

something that happened to me
long ago?

It's a very difficult problem
that we haven't solved.

Memory is the biggest mystery.

It's as big as the question of,
"What is the universe?

Why are we here?"

Could this 11-year-old boy

hold one of the keys
to unlocking the mystery?

On first glance,

Jake Hausler looks like
a normal fifth grader,

but as Washington University's
Roddy Roediger is discovering,

he seems to be anything but.

What happened Friday,
October 28, 2011?

World Series game seven.

Cardinals won 6-2.

Who were the pitchers
for the teams?

Chris Carpenter for St. Louis,
Matt Harrison for the Rangers.

The World Champs in 2011!

We're just getting to know Jake
and just starting to study him.

He's obviously a very bright kid

with a different kind
of very powerful memory.

Let's try a different day here.

How about May 4, 2013?

That was a Saturday,

and I saw Iron Man 3.

He appears to have
a pretty unique ability.

So he can tell you what he did
years ago to this date,

and that's very, very unusual,
in and of itself,

and to find it in a child
is particularly unusual.

When was Osama bin Laden killed?

May 2, 2011 in Pakistan,

May 1, 2011 in U.S.A.

I mean, it's amazing.

I've never felt like my memory
was particularly bad,

but compared to Jake's,
clearly it is.

It's just a mystery
as to what's going on here.

Jake can remember details

from almost every day
of his life since age seven.

Once he started speaking,
really,

we noticed he was different.

What are the 13 colonies?

Georgia, Connecticut,
Massachusetts, Maryland...

I remember taking him
to the grocery store one time

and he knew where
all the items were by aisle.

It's a little bit like having
a computer living with you.

We'd all remember getting a pet,
but the exact date?

What day did I pick up
Gracie in Wisconsin?

March 31.

Where did I fly into?

Minneapolis/St. Paul.

What did I eat for dinner
the night I was in Wisconsin?

Cheese curds?

That is correct.

There's no doubt that

there's something different
going on there.

What's different about Jake
is that he has HSAM:

Highly Superior
Autobiographical Memory.

Highly Superior, you can
remember days from your life

in lots of detail, like
what day of the week was it,

and you can't forget.

What about 2004?

Jim McGaugh is a pioneer
in the science of memory.

He discovered HSAM 15 years ago.

McGAUGH:
And when did you meet
with me?

June 28, 2008.

So far, out of the several
thousand tested,

he's discovered 55 adults
who have this amazing ability.

A Saturday at Panera Bread
in Newport Beach.

McGAUGH:
I can give them any date,
say ten years ago,

five years ago,
20 years ago, and so on.

Do you know when
Elvis Presley died?

August 16, '77.

And their performance will be
at least 80% correct,

and maybe 100% correct,

depending upon
the particular individual.

One of the best memories
McGaugh has ever tested

belongs to someone
you might recognize:

actress Marilu Henner
from the hit show Taxi.

I knew as a very young child

that I had
a very unusual memory.

They called me Miss Memory,
Miss UNIVAC, The Memory Kid,

things like that.

Name-calling aside,
they're not geniuses.

In fact, on average,
they have normal IQs.

They are not superior
in other forms of learning,

like book learning,

standard laboratory
learning tasks, and so on.

I think a misconception,

as you probably know,
that people have,

they think it's some type
of autistic savant thing,

that we're using some type
of mathematical calculation

like in Rain Man.

Yeah, definitely not Rain Man.

So what gives them
this amazing ability?

McGaugh has scanned
over a dozen HSAMs

and found some intriguing hints.

For example,
an area in the brain

associated with memory...
The uncinate fasciculus...

Is more active in HSAMs.

There are some differences
in the brain.

They're statistically
significant,

but they have not
given us a pattern

such that we can say,

"This is the neurobiological
basis of HSAM."

What is it about their brains
that enables this ability?

That's the open question.

And that's where Jake comes in.

He is the youngest person
ever discovered with HSAM,

and here
at Washington University,

scientists are mapping his brain
with new imaging technologies.

Over the next year,

they'll test his memory
while doing hundreds of scans.

All right, Jake,

so what happened
on April 8, 2013?

I went to the St. Louis Zoo.

When they are finished,
they will have perhaps

the most comprehensive picture
ever of a child's brain.

McDERMOTT:
We're getting loads and loads
of data on him.

It's very, very exciting.

I mean, to do this
in a normal person

in this comprehensive a way
would be really exciting,

and to be able to do it
on a child

who has particularly unique
abilities is extra special.

Then, they'll compare
Jake's scans to other children's

to see if they can unlock
the secret

of what makes his memory
so extraordinary.

It's a chance of a lifetime.

You can't write a grant saying

we're gonna go look
for someone like him

because you'll never
find him, right?

The hope is that
this little boy's brain

can help answer
some big questions

about how our memory works.

Jake clearly is able to extract

remarkable amounts
of information from his brain,

but we don't know if you or I
have that information in us,

but we just can't remember it,

or if it just doesn't get
encoded into our brain function

in the first place.

The mystery with Jake
and the other HSAMs is,

do they actually keep more
memories than the rest of us,

or do we all have this wealth
of detail

buried deep inside our brains...
We just can't get at it?

If we can understand
how he harnesses that,

to be able to generate that
within ourselves

could be a very powerful tool.

McGAUGH:
There is potential there

that we will learn something
truly new and important

about the functioning

of the most complicated
and interesting known structure

in the universe,
and that's our brain.

And the most important thing
it does is learn and remember.

But what exactly is a memory?

Amazingly, this simple question
has stumped thinkers for ages.

Until the 1950s,
few clues emerged,

and then came a single patient
who would change everything.

When I was a young researcher,

learning was learning
and memory was memory,

and it was just, you know,
a thing that happens.

And then along came the findings
of Brenda Milner

and her subject, HM.

HM stands for Henry Molaison,

patient zero
in the study of memory.

After a childhood
bicycle accident,

Molaison began to suffer
severe epileptic seizures.

To try and quell those seizures,

neurosurgeons performed
an operation

where they removed
the parts of his brain

that they thought were creating
those seizures.

Much of what they removed

came from a part of the brain
called the hippocampus.

After the surgery,
his seizures were gone,

but there was
an alarming side effect.

From that point forward,

he could no longer make
any new memories.

He was what we call
"densely amnesic."

It could only mean one thing:

the hippocampus must be
the part of the brain

responsible for creating
new long-term memories.

This in itself
was a breakthrough,

but that was just the start.

Do you know what you did
yesterday?

No, I don't.

How about this morning?

Brenda Milner wanted to know,
despite his amnesia,

could he still have
some form of memory?

He was a very nice person.

He was very cooperative.

Fortunately for us, he liked
doing tests, he liked puzzles.

So she came up with a puzzle
to trace a star shape

using only a mirror
to see his hand.

If you try this,
it's jolly difficult,

but normal subjects,
with practice, a few trials,

learn to do this thing.

Because HM appeared
to have zero ability

to make new long-term memories,
he should be hopeless.

He shouldn't be able
to learn anything.

How's he going to do?

I didn't know, I didn't know,
I had no idea.

And in fact, every time
Milner asked him to train,

he claimed he'd never done
the task before.

But his performance
betrayed him.

He got better and better,
until...

I was so excited,
because this was a breakthrough.

He can't remember
the events of his life,

but it seems that he can
possibly learn motor skills.

The fact that HM
could remember motor skills

but not new events in his life

meant that memory couldn't be
just one thing.

We had to leave behind
the notion

there was just
one kind of memory.

We now knew that there are
different kinds of memory,

and those different kinds
of memories

depend on different parts
of the brain.

Knowing where memories are
in the brain is one thing,

but how do they get there?

How does a long-term memory

get written in the brain
in the first place?

These are the questions
that have driven

Nobel Prize-winner Eric Kandel
for over 60 years.

It all started back in Vienna
on his ninth birthday.

I received a marvelous
little toy car

that I drove with great pleasure
through our small apartment.

Two days later
was Kristallnacht,

the infamous Night
of Broken Glass.

In that violent prelude
to the Holocaust,

thousands of Nazi soldiers
stormed the Jewish neighborhoods

in Vienna.

November 9,

there was a knock on the door,
and two Nazi policemen came in

and said,
"Pack all your things."

When we came back a week later,
everything of value is gone,

including my little toy car.

That was a very painful
experience.

A painful experience that would
define his life's work.

Everyone who went through
the Holocaust,

there are memories that
you can never forget.

Kandel wanted to know:

how did that experience
become a memory

he would carry with him
for life?

That got me interested in
psychology and psychoanalysis.

And when I got interested
in that, I said,

"What's the central question
in psychoanalysis?"

It's memory,
how we recall things.

But where to start?

His biggest lead was Milner's
early work with HM.

The hippocampus is crucial
for forming new memories.

But how do they get there?

Could there be a physical
mechanism on the cellular level?

So I thought I would record

from single cells
in the hippocampus,

and those cells
would be so unique,

they would speak to me
of memory storage.

Within months,

he was able to record the sound
of hippocampal neurons firing.

Our colleagues were euphoric.

But we didn't learn a darn thing
about learning and memory.

So I realized one needed to take
a reductionist approach,

and I thought I would use
a simple animal

with a simple nervous system,
simple behavior,

and try to study that.

Enter Aplysia Californica,
a giant sea slug

with one of the simplest nervous
systems in the animal kingdom.

One of the great giants
in the field

thought I was throwing
my career away.

In my naiveté, I was confident
that this would be right.

He thought if he could just
isolate the cellular changes

that occurred when Aplysia
learns simple tasks,

it would be the key
to understanding our memory.

Humans have neurons.

Sea slugs have neurons.

They're not that different,
right?

Even at the level of DNA,

our DNA's not so terribly
different.

The same fundamental kinds
of changes

should underlie memory.

To test his hypothesis,
Kandel's first step

was to create a memory
in the sea slug.

To do that, he trained it
to fear a light touch.

If you touch it in the siphon,
it'll withdraw the siphon.

The siphon is
the slug's water spout.

When it is touched, it also
withdraws its gill slightly

as a protective reflex.

But pair that touch...

Touch, shock.

With a mild shock, you get
a much stronger reaction.

And do it repeatedly...

Now when you touch
the animal's siphon again,

even weeks later,
without a shock,

it reacts as if it got shocked.

Somehow, it remembers that
that light touch means shock.

It has formed
a long-lasting memory.

The question is, how?

Kandel had a hunch.

If he could just replicate
that touch experiment

with single cells,

he could see exactly what was
going on to make a memory.

We could take the cells
out of the animal

and put it into the cell culture

and reconstruct
the neural circuit.

We could look at each level

and see what happens
with long-term memory.

That was this huge breakthrough.

What Eric Kandel really did was

he took this sort of phenomenon
of memory

and turned it
into a biological question.

"What are the changes
that are happening

that give rise to memory?"

To find out,

Kandel's team extracted
two neurons from the sea slug.

This is a sensory neuron
from its siphon,

and that's a motor neuron
from the tail.

They are connected
by a single synapse.

The synapse
is the point of contact

where one neuron
talks to another.

Then, to simulate
a long-term memory

just like with the live animal,

Kandel repeatedly stimulated
the sensory neuron.

And when he did, suddenly
something magical happened.

New synaptic connections
started to grow.

This made us realize
for the first time

that long-term memory
actually involves

an anatomical change
in the brain

whereby new connections
are being formed.

And that just really
blew us away

the first time we saw it.

That was a phenomenal discovery

because it showed us
for the first time

that memory involves
a structural physical change

in the brain.

That became the foundation

for our whole conceptual basis
for understanding memory.

Using today's technology,

you can witness this process
first-hand.

This shows you the nucleus
in the cell.

After repeated stimulation,
the neuron's nucleus

starts to pump out these tiny
glowing specks called mRNA,

recipes for building proteins.

They're about to travel
down to the synapse

with instructions
to build new connections.

And you see
this magnificent voyage

that this particle,

which is carrying messenger RNA
to the synapses.

When it gets there,
the instructions are released

and the new connections grow,
seen here in green.

We're seeing a memory being
formed in front of your eyes.

These anatomical changes occur
in your brain

when you learn
and remember something.

From sea slugs to humans,
these physical changes

are considered
the biological basis of memory.

It's an article of faith
at this point

that the mechanisms
that he has uncovered

are fundamental ones to learning
and memory for all of us.

Kandel's work launched
a new way of probing memory,

grounded in biology and built
around a simple premise:

the growth of new connections

is what allows a memory
to persist

for days, months, even years.

But that was just a piece
of the picture,

a basic mechanism
for how memory works

at the level of single cells.

Even in a sea slug, a memory
is made up of about 50 neurons

out of 20,000.

In a human, it's more like
tens of thousands

out of 100 billion.

Somehow, it's this network
that stores a memory.

Which begs the question:

where exactly does a particular
memory live in us?

To this day,
that remains a mystery,

but we aren't without clues.

In the last 25 years,
new imaging tools

have allowed a generation
of explorers

to chart memory
in the human brain.

And today, we can finally begin
to draw a rough map

of where some of our most
treasured memories live.

Take something like
a first kiss.

Most people remember
their first kiss.

Do I remember my first kiss?

I do.

When did I kiss that girl?

There was this Italian,
this dashing Italian.

She was like, "This is something
people do who like each other,"

and I was, "Okay, I like you."

I remember, you know,

sort of planning this kiss
for, like, a week!

Her friend whispered to me,
"Make a move and walk faster."

And all of a sudden,
Lauren and I were alone

in kind of a grove of trees.

He takes my face like this
and plants one on me!

It was like the universe
exploded or something like that.

It just felt like suddenly,
everything was different.

The question becomes then,
where is the memory?

And what we started
to understand is that

there isn't a nicely
sort of packaged memory

that's sort of folded up
like a letter

and placed inside of an envelope

in one specific area
of the brain.

Different parts of memories

are coded in different locations
of the brain.

Think about your first kiss.

The visual elements are coded
at the back of the brain

in the visual cortex.

The smell components are coded
in the olfactory cortex

just above the nose.

The motoric,
the kinesthetic elements,

they're coded up here
in the motor cortex.

The emotional elements are coded

in deep brain structures
like the amygdala.

And together,
it is the hippocampus

that is going to grab ahold

of those individual
brain anatomical areas,

those balloons of information,

and it is going
to bind them together

and produces a memory that
you're capable of remembering.

So if different parts
of a memory

live in different parts
of the brain,

and we know that the growth
of new connections

is important for storing them,

that would suggest that
every memory

is physically tattooed
onto our brains.

So how come we don't
remember them all?

The question is, if there are
these structural changes

that give rise to memory,

but memories are changeable
and dynamic,

how can that be?

Perhaps the answer can be found

in the act of remembering
itself.

Think about it:

a memory only comes alive
when you recall it.

What happens in your brain

each time you recollect
a past experience?

That's what Karim Nader
wondered.

His quest for answers started
when he was a grad student

at one of Kandel's lectures.

Eric Kandel came
and gave this brilliant talk.

You know, there are examples
for this...

He had beautiful pictures

showing that synapses
could grow over time.

The work is very elegant.

It took everyone's breath away.

Looking at those pictures
gave Nader an idea.

"Hey, why would all of this
have happened just once?

"Wouldn't it be cool
if all of this happened again

when you recall the memory?"

If Kandel's work
helped establish

that memories can't form

without new proteins
that build new connections,

what happens
to those connections

when you remember something?

At the time, memory was pictured
kind of like a library.

The underlying dogma was that
when you formed a memory,

it was filed away in your brain,
and that's it.

It was there now forever.

It's called consolidation.

You can't modify it, it just is.

It's just in the brain.

So when you remember
your first kiss,

you pull out that book,
look at it, and put it back.

Though it may fade over time
or get lost in the stacks,

the original story, or memory,
is always still there.

Nader wondered,
"Could this really be true?

"Or is it possible that just
the act of recalling the memory

could rewrite the story?"

To find out, Nader designed
an experiment.

When Karim told me he wanted
to do that experiment,

I probably said something like,

"Don't do it,
don't waste your time."

But being a smart guy,
he went off and did it.

So Nader decided
to put his idea to the test.

He started by training rats
to fear the sound of a tone...

Okay, so there's the tone.

By pairing it with a mild shock.

Now there's the shock.

So right now he's really scared,
he doesn't like this at all.

Just like Kandel's sea slugs,

the rats quickly learn
to fear the tone alone.

They have formed a long-term
memory that the tone

predicts shock.

So every time it hears
the tone...

So you see,
even though there's no shock,

the animal's freezing,
it's afraid.

We know the rats' brains
have built new connections

to store the memory.

But what happens
to those connections

when the rat recalls the memory?

To find out, Nader first plays
the tone to remind the rat

of his fear,
and when he freezes...

The next part is gonna be giving
him a compound directly.

The compound is anisomycin,

a drug known
to block the proteins needed

to build the connections
that store new memories.

But Nader's rats have already
formed the memory;

they're just recalling it.

If memory consolidation really
is like a book in a library,

the drug should have no effect.

The rats' brains should have
built a permanent memory

and they should still freeze
when they hear the tone.

So if the memory
is wired in the brain,

this drug should have
absolutely no effect.

But now when Nader
plays the tone...

Oh my God, so now you see.

He keeps moving.

You would think that the animal
should be freezing if it

still had the memory there,
but now it's acting as if

the memory has been erased
from its mind.

As if it never learned to fear
the tone in the first place.

The memory appears to be gone.

My jaw just dropped.

I just couldn't believe it.

So I ran into
my supervisor's office going,

"Holy,

I can't believe
this happened."

I mean the probability of this
happening is like zero, right?

Because a drug known to block
the formation of new memories

also blocked them during recall,
it means the act of remembering

must make memories
vulnerable to change.

In other words:

It's not this you have a memory,
you encode it,

and it's stuck there.

But instead what it means
is that every time

that memory is recalled,
it is vulnerable to alteration.

Nader's discovery that any time
you recall the memory

you essentially disrupt it
was a significant advance.

It changes everything we think
about memory.

It turns out memory
is not at all actually

like putting a book away
in the library of the brain,

but it's more like bringing up
a file on your computer,

constantly modifying that file.

The theory is, every time
you recall something,

you have to pull it up
off the hard drive to view it.

To return it
to long-term memory,

you have to hit "save"
and reconsolidate the memory

by creating new proteins
to essentially rewire the memory

into your brain.

Imagine something precious
in a box.

And then each time you take it
out, it changes a little bit.

And then you put it back.

Then take it out,
changes a little bit.

That's how your memory works.

The idea that the simple act
of remembering

could make your memories
vulnerable to change

transformed our understanding
of memory.

Within a few years, Nader's
findings were replicated

in dozens of species and led
to over a thousand experiments,

even reportedly inspired
the movie

Eternal Sunshine
of the Spotless Mind.

Just focus on the memories.

Here at Lacuna,
we have a safe technique

for the focused erasure
of troubling memories.

But what if this isn't
just the stuff of movies?

What if it's possible to use
reconsolidation in humans?

Perhaps to erase
certain memories,

like the ones
that keep you up at night.

Heights...

I'm terrified of heights.

I don't want to be on a ladder.

I don't want to be
on the second floor.

I don't like to be looking down.

I can't tell you the last time
I've been in a pool,

I can't tell you the last time
I've owned a bathing suit.

But, I mean, the water gets like
probably right here,

and it's like the...

Elevators.

Snakes are the worst.

I don't know what it is
about bees,

but I just can't...
I can't be around them.

Spiders.

I'm petrified of spiders.

Even the smallest ones.

Terrified.

If I see a spider
I don't want to come near it.

I'm really scared of spiders.

Or at least I used to be.

But now I'm just completely
relaxed sitting here

with a tarantula.

And it's really crazy.

Ever since she was
a little girl,

Sasha de Waal has been plagued
by her fear of spiders.

But thanks to a new therapy
using reconsolidation,

that fear seems to have
been erased.

Yeah.

I'm petting
a poisonous spider indeed.

The scientist who cured Sasha
is Merel Kindt

from the University
of Amsterdam.

When she heard about
Karim Nader's work,

she immediately saw
the potential.

So I was really thrilled.

I realized if this is going
to work for humans,

this is, yeah,
very important news.

So can you tell me a bit more
about your fear of spiders?

Using reconsolidation,
she has developed a treatment

to erase patients'
life-long fears.

They just scare me.

Just fear.

When I sleep I dream about it,
I'm just very scared.

For the treatment we will walk
to the other side of the room,

and there is a terrarium tank
with a tarantula in it.

I'm going to ask you
to touch the tarantula.

Okay?

They're not poisonous, right?

Yeah, well, all tarantulas
are poisonous.

Walk to the yellow line.

Very good, you are
doing very good.

Just like with Nader's rats,
the first step is to get Jeroen

to draw up the memory
of his fear.

You're doing very good.

We ask our participants
to approach the tarantula,

which triggers
the original fear memory.

How much distress
do you feel right now?

Dry mouth.

I feel shaking.

You are doing very, very well.

Try to look here.

Don't avoid it.

Stay here, it's important
that you see it.

Yeah?

Just put your hand here.

And then stop, yeah?

What do you think
that will happen?

Approaching the spider

makes the fear memory unstable.

Yeah.

Okay, very good, we go
to the other side of the room.

Such that if we give propranolol

after the exposure
to the tarantula,

the drug can interfere
with the restabilization

of the original fear memory.

Propranolol is
a blood-pressure medication

that blocks the release of
noradrenaline in the amygdala,

the fear center of the brain.

Since noradrenaline is part
of the brain's anxiety signal

during a fearful event,
blocking it after recall

seems to disrupt
the reconsolidation

of the fear part of the memory.

What is very important is that
it is not a forget pill.

If we do not trigger
the memory reactivation,

the drug will not work.

The next day Jeroen returns.

What we are going
to do is again,

walking to the other
side of the room

and I'm going to ask you
again to touch the spider.

You can touch it
here at the backside.

Very good.

Did you touch it,
did you feel it?

Yeah, yeah.

Okay, try it again.

It felt like rubber.

Yeah, try it again.

Oh, man.

Okay.

It takes a few tries,
but after just minutes...

Do it again.

Very good, yes, yes.

Yes.

How does it feel
to touch a tarantula?

Like touching a hamster.

Yeah.

Maybe he likes it.

So far Kindt's repeated
this work in over 30 people

with spider phobia and other
anxiety disorders, and...

The effects were so overwhelming

that I did not believe them
initially.

But in fact, the therapy worked

in every spider phobe
she tested, even a year later.

It was unbelievable,
and I was standing there,

like, how can this be possible?

It's my new friend.

It's really confusing.

It's like a contradiction...

Yeah, yeah, contradiction.

With how I used to feel
and how I feel now.

It's so strange,
like I am someone else now.

We of course cannot prove
that we delete or even erase

the original fear memory,
because we can only observe

the new behavior, but given that
the fear does not come back,

we hypothesize that
the previously formed memory

are in fact deleted.

Treating people with spider
phobia is only the first step.

Kindt is now among a handful of
scientists using reconsolidation

to treat a variety of disorders
from drug addiction to PTSD,

and though the research
is in its infancy,

early results have been
promising.

I am very hopeful that the
reconsolidation intervention

will be further developed

for people with post-traumatic
stress disorder.

But reconsolidation is more
than just a therapeutic tool.

If the act of recalling a memory
makes it vulnerable to change,

this may also explain something
we've known all along...

That our memory is often
an unreliable narrator.

I could swear by anyone, pass
every lie detector test that...

I had met Mother Teresa,
but I hadn't.

Something that I wanted to
happen, but it never did happen.

I believe that my earliest
memory was a very happy memory

of going to a movie called
The Greatest Show on Earth.

♪♪

And it wasn't until much later
I found out that the movie

was released when I was
eight years old.

So it couldn't have been
my earliest memory.

This comes as no surprise
to Elizabeth Loftus.

She's spent the last 40 years

exploring exactly how unreliable
our memory is.

I think people ought to pay
more attention to the fact

that there are memory errors
all around them.

Her work has inspired
a generation of researchers,

including psychologist
Julia Shaw.

The question isn't,
do we have false memories?

It's, how false
are our memories?

There are so many things

that can and do go wrong
along the way.

To find out how wrong,
Shaw has designed perhaps

the most comprehensive study
ever on false memory.

She starts by recruiting
over a hundred people

for what they think is a study
about their childhood memories.

So this is my first meeting
with the participant.

The first event which
we'll be talking about

was a time when you were 12
and you moved from Trinidad

to Kelowna with your family.

I hated the move.

Actually the study is to see
if it's possible to implant

a false memory
about committing a crime.

I had colleagues saying,
"This isn't going to work.

"There's no way you will get
individuals to think

that they committed a crime
that never happened."

She begins with a true event
gathered from their parents...

In this case a family move.

We moved around like
every year kinda thing.

But this was just a trick
to gain trust.

The next step is to introduce
the false memory:

a fight so severe
that the police were called.

So the other event which
your parents report happening

was when you were 14 years old
you initiated a physical fight

and the police
called your parents.

They said it happened
in Kelowna, in the fall

and you were with Ryan
when it happened.

Only two of the details
are real:

the name of the best friend and
the place she lived at the time.

The rest is made up.

Honestly, I don't remember.

Like I don't know what
you're talking about.

I don't.. I feel like...
I don't think

I've ever been in a fight.

I'm so confused.

Shaw then turns to a series
of cognitive techniques

known to induce false memories,

starting with
an imagination exercise.

I'd like you to relax,
close your eyes

and focus your attention on
trying to retrieve this memory.

Okay.

Bolstered with
a little social pressure...

This might seem a bit strange,

but it does work
for most people.

Okay.

Subtly introducing this notion

that "it works for most people
if they try hard enough,"

which is a subtle form
of social manipulation.

And ask the participant
to visualize certain details

of the stories.

Introducing things that are easy
to picture first.

Picture yourself
at the age of 14.

"Picture yourself
at the age of 14."

That's an easy thing to picture.

In Kelowna.

In Kelowna, the place that
she lived at the age.

Also easy to picture.

And it's fall.

It's fall,
everybody can picture fall.

And you were with Ryan
when it happened.

When people imagine events
that might have occurred

in their past, we know
that that's a potent way

of creating a false memory.

After giving the memory
a week to set,

she brings the participant back.

Okay, so, welcome back.

And so by the time we get
to interview number two,

we're seeing a different story.

I remember, like,
a verbal fight and maybe I...

It seems so unlike...
but maybe I pushed or something?

Good, okay.

So this is where she's first
fully buying into this idea

that she's actually had a fight.

I feel like she pushed me first.

Okay.

And this person
is starting to picture

how it could have happened.

And "what could have been"

turns into
"what would have been"

turns into "what was."

So by the third interview,
the memory has taken hold.

I think the cops showed up,
and we were kind of having

a... maybe like a verbal
kind of fight

and then it kind of maybe got
into a push.

And it wasn't just this once.

Shaw was able to convince

over 70% of participants
that they committed a crime.

I think I just lost it.

Couldn't take it anymore.

I was incredibly surprised
at the rate that I had

in terms of successfully
implanting these false memories.

You physically feel
things about it?

Yes.

And yet there we were,
and they just kept coming

and coming and coming.

So much so, Shaw's team
cut the study short.

So this is a false memory study.

I'm so embarrassed.

And the ramifications go way
beyond fooling college students.

False memory studies like this

question one of the cornerstones

of the criminal justice system.

In those hundreds of cases
where DNA testing has proven

that these individuals
were wrongly convicted,

about three-quarters of the time
the convictions were based

on faulty eye witness testimony.

So if our memories are
more malleable than we think,

and we can change them, even
erase some of them, what's next?

Will there ever be a day when
at just the push of a button,

we can implant or edit
specific memories at will?

Is this your first trip?

Like in the movies?

The seed that we plant
in this man's mind

will grow into an idea.

This idea will define him.

It may come to change...

well, it may come to change
everything about him.

Movies like Inception,
Total Recall, Eternal Sunshine,

of course they're possible.

If mice had Hollywood, then it's
possible in practice right now.

In fact, here
at Columbia University,

Christine Denny is one of
a handful of neuroscientists

who can do just that.

It does seem like
science fiction.

But we are really doing
Inception in our lab

with turning on and off
memories.

It's called optogenetics,
a technique so revolutionary

it allows us not only
to map a specific memory,

but manipulate it with lasers.

At least in these little guys.

These mice might not
look so special.

You could not tell my mice apart
from a mouse on the street

or wherever you would go
to a pet store and buy a mouse.

They don't look any different.

But they are.

These are genetically
modified mice

that allow Denny to record
specific memories

and turn them on and off
at will.

To demonstrate,
she starts by putting a mouse

in a new environment.

You can see that the mouse
is just sitting here

in the corner, freezing.

Basically scared
of the environment.

That's because it's bright.

There's no place to hide.

But the goal isn't
to frighten mice.

She wants to see
if she can override this fear

by playing back a happy memory
she recorded yesterday.

What we did is labeled
a positive memory

in the brains of these mice.

Yesterday this same mouse
got to explore the kind of place

it naturally likes: dimly lit,
full of soft bedding,

with a nice place to hide.

And while he was
scurrying around, Denny recorded

the exact neurons that fired
when he made a memory

of that pleasant place.

The cells that are labeled
here in green,

when I turn on the laser, those
cells will turn on the memory.

But how?

How do you record
a specific memory?

And how do you get brain cells
to respond to light?

Here's where the sci-fi wizardry
comes in.

We genetically engineered mice
so that we can permanently label

an individual memory.

The key is this mouse's
special genome.

It's bred to carry a piece
of DNA from algae

that has the code for
a light-sensitive protein.

In nature, that protein allows
the algae to respond to light.

In Denny's mice,
it just sits there quietly

in the mouse's genome,
not doing anything until...

When you inject a drug
right before you expose them

to this positive experience.

The drug switches that gene on,
telling any brain cells

that fire within the hour

to install this light-sensitive
protein on their surfaces.

As the mouse is exploring
a pleasant environment,

any neurons that fire will leave
a footprint of the memory

in the mouse's brain.

After the drug wears off,

only those cells
will respond to light.

Meaning:

It's basically like a switch.

So what you can then do is use
a laser to control these cells.

These tiny fiber optics
can shine light

directly into the mouse's brain.

And what we're going to try to
do now is to turn on these cells

that we've labeled
with a positive memory.

Right now the mouse is scared,
but if Denny is right,

the laser should activate the
exact same neurons that fired

when the mouse was making
a happy memory,

effectively causing it to relive
that positive experience.

Okay, so watch now what happens

when I'm going to turn
this laser on.

You can see that
the animal's actually smelling,

grooming himself, which is
a sign that he feels safe.

But turn the laser off...

And you can see that the animal
is resuming its behavior

of freezing in the corner.

Denny can now trigger
this memory at will.

On.

Off.

I think the first time we did
it, we didn't believe it.

But when you see inside
of the brains of these mice

and then to think that you're
only manipulating those cells

and changing the behavioral
output of the animal,

that's... yeah, science fiction.

This is potentially

one of the most important
new developments

in memory research because
it suggests a level

and precision of control
over memory that we've really

never seen before.

A degree of precision
many scientists think

we might have
over our memories someday.

I think that it's a matter

of when this happens,

not a matter of
if it'll happen in people.

Which raises the question,

if by a flick of a switch we
could edit that first kiss

or erase that argument
with a spouse,

would we want to?

What scientists now
are starting to realize is

that we can modify memories
in some remarkable ways.

How do we think about that?

By starting to manipulate
those memories,

are we suggesting that
evolution got it wrong?

Could it be possible

that our memories are built
the way they are for a reason?

Why would we be constructed
with a memory system

that is so potentially open
to suggestion and change?

Perhaps Jake,
the 11-year-old boy

with the amazing memory,

can help answer that question
one day.

After months of scans,
scientists are still searching

for something to explain
his extraordinary ability.

But even if they don't
find anything,

that's an important clue.

Jake's already telling us
something about our memories,

namely that the human brain has
the capability to remember

your entire life
in great detail.

It's a fascinating question
of, why don't we?

Consider Jake.

Though he and other HSAMs love
having their special memories,

even at his young age, he is
aware that it comes at a price.

Just like to everything,

there's an upside
and there's a downside.

The downside is you can remember
every bad thing

that happens to you.

McCAUGH:
They live in different worlds

than the worlds
that you and I live in.

And you have to wonder, would
you like to live in that world?

A world where you can't forget.

Forgetting is probably
one of the most important things

that brains will do.

Perhaps evolution was smart
enough to design a system

that stores only stuff
that's important.

Could it be that what we think
of as memory's flaws

are actually part
of its strength?

Maybe we have a misconception of
what the purpose of memory is.

That we think of it more
as an accurate recording

of past experiences
as opposed to a creative process

of combining our experiences
over time.

Perhaps the ultimate goal
of memory is not to retain

every single fact
that you've learned.

If you had just this picture-
perfect back catalogue

of 30, 40, 50, 60 years
of experience,

imagine how hard it would be
to pick out

the individual specific
experiences that you need

at any one moment

against the backdrop
of that sea of noise.

Somehow this complex
choreography of single cells

adds up to our memory,

a mysterious system that allows
us to time-travel to the past

and imagine our future.

But perhaps memory's
ultimate gift

is a way to navigate
that sea of noise

so we can pick out
the experiences

that each of us weave together
to tell the story of our lives.