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Greg Gage: Who wouldn't love
acing a geography exam,
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remembering all the locations
of the countries on a map
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or avoiding embarrassing situations
of suddenly forgetting the person's name
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standing right in front of you.
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It turns out that memory,
like other muscles in the body,
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can be strengthened and enhanced.
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But instead of practicing
with flash cards,
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there may be an interesting way
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that we can hack our memory
while we sleep.
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(Music)
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Why do we sleep?
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This has been a question asked
since the early days of civilization.
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And while we may not know
the exact answer,
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there are a number of really
good theories about why we need it.
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Sleep is when the brain transfers
short-term memories
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experienced throughout the day
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into long-term memories.
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This process is called
memory consolidation,
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and it's the memory consolidation theory
that has scientists wondering
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if we can enhance
certain memories over others.
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There was a paper recently
in the journal "Science"
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by Ken Paller and his colleagues
at Northwestern
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that seemed to show that this may be true,
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and that piqued our curiosity.
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Joud has been working
on a DIY version of this task
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to see if we can improve memories
through the use of sound in sleep.
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So Joud, how do you test if we can
improve our memories with sleep?
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Joud Mar’i: We need a human subject.
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[Step 1: Play a game]
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We have a memory game
that we have on an iPad,
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and then we make our subject
play this game
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and remember the images
and where they appear on the screen.
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GG: So this is like a memory game
you used to play as a child,
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which picture was where.
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And we tie each picture
with a sound that represents it.
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JM: So, if you can see
a picture of a car, for example,
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and you would hear the car engine.
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(Car engine starting)
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GG: Just before you go to sleep
we're going to test you.
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We're going to see how well
you remember where the pictures are.
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Every time you see the picture,
you're going to hear the sound.
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And now comes the experiment.
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You're going to go take a nap.
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[Step 2: Take a nap]
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And while you're sleeping,
we're going to be recording your EEG.
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JM: And then we wait for them to go
into what's called the slow-wave sleep,
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which is the deepest phase of your sleep
where it's really hard for you to wake up.
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GG: OK, pause.
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So, here's some information on sleep.
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There are four stages:
we have lighter stages of sleep and REM,
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but what we're interested in
is called slow-wave sleep.
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And it gets its name
from the electrical signals
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called Delta waves
that we record from the brain.
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This is the part of sleep
where scientists believe
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that memory consolidation can happen.
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In this deep period of sleep,
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we're going to do something
that you don't know we're going to do.
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JM: Here's where the tricky part comes,
and we start playing our cues.
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(Car engine starting)
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GG: Do you play all the cues?
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JM: No. We only want to play half of them
to see if there's a difference.
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GG: So your hypothesis is
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the one that they were listening to
while they're sleeping
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they're going to do better at.
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JM: Yes, exactly.
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GG: When you wake back up
and play the game again,
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do you do better or worse
than before a nap?
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What we found is that if we played you
a cue during your sleep,
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for example, a car --
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You would remember
the position of that car
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when you woke back up again.
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But if we didn't play you the cue
during the sleep,
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for example, a guitar,
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you'd be less likely to remember
that guitar when you woke up.
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The memories that were cued
they remembered better
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than the ones they weren't,
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even though they don't remember
hearing those sounds?
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JM: Yes, we ask them.
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GG: We know they're sleeping,
they can't hear it, they wake up,
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they do better on those
than the ones you didn't play.
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GG: That's amazing.
JM: It's like magic.
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GG: Joud ran this experiment on 12 people
and the results were significant.
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It's not that you remember things better;
it's that you forget them less.
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I was a huge skeptic when I first heard
that you could do better at a memory test
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just by playing sounds during sleep.
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But we replicated these experiments.
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The facts and memories we collect
throughout the day are very fragile,
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and they are easily lost and forgotten.
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But by reactivating them during sleep,
even without us being aware,
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it seems like we could make them
more stable and less prone to forgetting.
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That's pretty incredible.
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Our brains are still active
even when we're not.
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So if you're like me and a bit forgetful,
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perhaps a solution is a pair
of headphones and a soft couch.