NARRATOR: Memory... it's the key to our identity.
Without memory, we're nothing.
It's who we are.
NARRATOR: But how does it actually work?
It's a huge mystery.
NARRATOR: Today, scientists are probing our brains
like never before.
We're seeing a memory being formed in front of your eyes.
NARRATOR: 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.
NARRATOR: From editing memories...
We can implant a false memory.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: "Memory Hackers," right now on NOVA.
Major funding for NOVA is provided by the following...
I remember...
Hmm...
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: Or saddest...
The death of my father.
NARRATOR: We are little but the sum of our memories.
DANIELA SCHILLER: It's who we are.
That's how we understand ourselves and our lives.
NARRATOR: 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.
NARRATOR: How is this gift possible?
How does the world get into our heads
and turn into a memory?
How does memory actually work?
Wow.
NARRATOR: 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.
RODDY ROEDIGER: 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.
SCHILLER: Memory is the biggest mystery.
It's as big as the question of, "What is the universe?
Why are we here?"
NARRATOR: 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.
ROEDIGER: 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.
ANNOUNCER: 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.
ROEDIGER: 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.
NARRATOR: Jake can remember details
from almost every day of his life since age seven.
Once he started speaking, really,
we noticed he was different.
MOM: What are the 13 colonies?
Georgia, Connecticut, Massachusetts, Maryland...
DAD: 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.
NARRATOR: We'd all remember getting a pet, but the exact date?
DAD: 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.
(laughing)
There's no doubt that
there's something different going on there.
NARRATOR: 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?
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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, defitely not Rain Man.
NARRATOR: 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.
NARRATOR: 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 imagingechnologies.
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.
NARRATOR: 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.
NARRATOR: Then, they'll compare Jake's scans to other children's
to see if they can unlock the secret
of wt makes his memory so extraordinary.
MAN: 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?
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
WALKER: From that point forward,
he could no longer make any new memories.
He was what we call "densely amnesic."
NARRATOR: 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.
BRENDA MILNER (recording): Do you know what you did yesterday?
HM (recording): No, I don't.
MILNER (recording): How about this morning?
NARRATOR: Brenda Milner wanted to know, despite his amnesia,
could he still have some form of memory?
BRENDA MILNER: He was a very nice person.
He was very cooperative.
Fortunately for us, he liked doing tests, he liked puzzles.
NARRATOR: So she came up with a puzzle to trace a star shape
using only a mirror to see his hand.
MILNER: If you try this, it's jolly difficult,
but normal subjects, with practice, a few trials,
learn to do this thing.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
ERIC KANDEL: I received a marvelous little toy car
that I drove with great pleasure through our small apartment.
NARRATOR: 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.
KANDEL: 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.
NARRATOR: A painful experience that would define his life's work.
KANDEL: Everyone who went through the Holocaust,
there are memories that you can never forget.
NARRATOR: 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.
NARRATOR: 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?
KANDEL: 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.
NARRATOR: Within months,
he was able to record the sound of hippocampal neurons firing.
KANDEL: 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.
NARRATOR: Enter Aplysia Californica, a giant sea slug
with one of the simplest nervous systems in the animal kingdom.
KANDEL: 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.
NARRATOR: 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.
NARRATOR: 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.
KANDEL: If you touch it in the siphon, it'll withdraw the siphon.
NARRATOR: 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...
KANDEL: Touch, shock.
NARRATOR: 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.
KANDEL: 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.
MARTIN: 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?"
NARRATOR: 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.
KANDEL: The synapse is the point of contact
where one neuron talks to another.
NARRATOR: 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.
KANDEL: 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.
JOE LEDOUX: 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.
NARRATOR: Using today's technology,
you can witness this process first-hand.
This shows you the nucleus in the cell.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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?
(laughing)
I do.
When did I kiss that girl?
There was this Italian, this dashing Italian.
MAN: She was like, "This is something people do who like each other,"
and I was, "Okay, I like you."
MAN: 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.
MATT WALKER: 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.
NARRATOR: 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?
NARRATOR: 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...
NADER: He had beautiful pictures
showing that synapses could grow over time.
The work is very elegant.
It took everyone's breath away.
NARRATOR: Looking at those pictures gave Nader an idea.
NADER: "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?"
NARRATOR: 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.
NARRATOR: It's called consolidation.
RAMIREZ: You can't modify it, it just is.
It's just in the brain.
NARRATOR: 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.
JOE LEDOUX: 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.
NARRATOR: So Nader decided to put his idea to the test.
He started by training rats to fear the sound of a tone...
(ringing)
Okay, so there's the tone.
NARRATOR: 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.
NARRATOR: 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...
(ringing)
NADER: So you see, even though there's no shock,
the animal's freezing, it's afraid.
NARRATOR: 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?
(ringing)
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.
NARRATOR: 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.
NADER: So if the memory is wired in the brain,
this drug should have absolutely no effect.
NARRATOR: But now when Nader plays the tone...
(ringing)
NADER: Oh my God, so now you see.
NARRATOR: 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.
NARRATOR: 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 (bleep) (bleep) (bleep),
I can't (bleep) believe this happened."
I mean the probability of this happening is like zero, right?
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
MARK RUFFALO: Just focus on the memories.
Here at Lacuna, we have a safe technique
for the focused erasure of troubling memories.
NARRATOR: 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.
MAN: Heights...
I'm terrified of heights.
WOMAN: 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... (hyperventilating)
Elevators. (chuckles)
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.
NARRATOR: 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.
(laughing): I'm petting a poisonous spider indeed.
NARRATOR: 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.
MEREL KINDT: 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?
NARRATOR: 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.
NARRATOR: Just like with Nader's rats, the first step is to get Jeroen
to draw up the memory of his fear.
(breathing heavily)
KINDT: 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?
KINDT: Approaching the spider
makes the fear memory unstable.
Yeah.
Okay, very good, we go to the other side of the room.
KINDT: Such that if we give propranolol
after the exposure to the tarantula,
the drug can interfere with the restabilization
of the original fear memory.
NARRATOR: 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.
NARRATOR: 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.
(chuckles)
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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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?
(chuckles)
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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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."
NARRATOR: She begins with a true event gathered from their parents...
in this case a family move.
We moved around like every year kinda thing.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
SHAW: 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."
NARRATOR: 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.
NARRATOR: 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?
(quietly): Yes.
And yet there we were, and they just kept coming
and coming and coming.
NARRATOR: So much so, Shaw's team cut the study short.
So this is a false memory study.
(laughing): I'm so embarrassed.
NARRATOR: And the ramifications go way beyond fooling college students.
False memory studies like this
question one of the cornerstones
of the criminal justice system.
LOFTUS: 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.
NARRATOR: 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?
NARRATOR: 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.
NARRATOR: In fact, here at Columbia University,
Christine Denny is one of a handful of neuroscientists
who can do just that.
CHRISTINE DENNY: It does seem like science fiction.
But we are really doing Inceptio in our lab
with turning on and off memories.
NARRATOR: 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.
NARRATOR: 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.
DENNY: You can see that the mouse is just sitting here
in the corner, freezing.
Basically scared of the environment.
NARRATOR: 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.
NARRATOR: 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.
DENNY: The cells that are labeled here in green,
when I turn on the laser, those cells will turn on the memory.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: 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.
NARRATOR: But turn the laser off...
DENNY: And you can see that the animal is resuming its behavior
of freezing in the corner.
NARRATOR: 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.
SCHACTER: 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.
NARRATOR: A degree of precision many scientists think
we might have over our memories some day.
RAMIREZ: I think that it's a matter
of when this happens,
not a matter of if it'll happen in people.
NARRATOR: 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?
NARRATOR: 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?
NARRATOR: 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.
DOSENBACH: 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?
NARRATOR: 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.
JAKE: 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?
NARRATOR: 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.
NARRATOR: Could it be that what we think of as memory's flaws
are actually part of its strength?
MARTIN: 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.
WALKER: 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.
NARRATOR: 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.
The investigation continues online,
This NOVA program is available on DVD.
To order, visit shopPBS.org, or call 1-800-PLAY-PBS.
NOVA is also available for download on iTunes.