TED Talks · Neuroscience

Your memory while you sleep

Who wouldn't love acing a geography exam, remembering all the locations of the countries on a map,

Level: B1 · 72 sentences

Transcript

  1. Who wouldn't love acing a geography exam,
  2. remembering all the locations of the countries on a map,
  3. or avoiding embarrassing situations of suddenly forgetting the person's name standing right in front of you?
  4. It turns out that memory, like other muscles in the body,
  5. can be strengthened and enhanced.
  6. But instead of practicing with flashcards,
  7. there may be an interesting way that we can hack our memory while we sleep.
  8. Why do we sleep?
  9. This has been a question asked since the early days of civilization.
  10. And while we may not know the exact answer,
  11. there are a number of really good theories about why we need it.
  12. Sleep is when the brain transfers short-term memories experienced throughout the day into long-term memories.
  13. This process is called memory consolidation.
  14. And it's the memory consolidation theory that have scientists wondering if we can enhance certain memories over others.
  15. There was a paper recently in the journal Science by Ken Poller and his colleagues at Northwestern that seemed to show that this may be true.
  16. And that piqued our curiosity.
  17. Jude has been working on a DIY version of this task to see if we can prove memories through the use of sound and sleep.
  18. So Jude. How do you test if we can prove our memories with sleep?
  19. We need a human subject.
  20. We have a memory game that we have on an iPad,
  21. and then we make our subject play this game and remember the images and where they appear on the screen.
  22. So this is like a memory game that you used to play when you were a child,
  23. which picture was where.
  24. Exactly. And we tie each picture with a sound that represents that picture.
  25. So if you can see a picture of a car,
  26. for example, and you would hear the car engine.
  27. Just before you go to sleep, we're going to test you.
  28. We're going to see how well do you remember where the pictures are.
  29. Every time you see the picture, you're going to hear the sound.
  30. And now comes the experiment.
  31. You're going to go take a nap.
  32. And while you're sleeping, we're going to be recording your EEGs.
  33. And then we wait for them to go into what is called the slow wave sleep,
  34. which is the deepest phase of your sleep where it's really hard for you to wake up.
  35. Okay, pause. So here's some information on sleep.
  36. There are four stages.
  37. We have lighter stages of sleep and REM.
  38. But what we're interested in is called slow wave sleep.
  39. And it gets its name from the electrical signals called delta waves that we record from the brain.
  40. Now this is the part of sleep where scientists believe that memory consolidation can happen.
  41. In this deep period of sleep,
  42. we're going to do something that you don't know that we're going to do.
  43. Here's where the tricky part comes and we start playing our cues.
  44. Do you play all the cues from the thing?
  45. OK, no, the interesting part is we only want to play half of them to see if there's a difference.
  46. So your hypothesis is the one that they were listening to while they're sleeping,
  47. they're going to do better at when they wake up.
  48. Yes, exactly. When you wake back up and you play the game again,
  49. do you do better or worse than before a nap?
  50. What we found is that if we played you a cue during your sleep, for example,
  51. a car, you would remember the position of that car when you woke back up again.
  52. But if we didn't play you the cue during the sleep, for example, a guitar,
  53. you would be less likely to remember that guitar when you woke up.
  54. The memories that were cued, they remembered better than the ones they weren't,
  55. even though when they woke up, they don't remember hearing those sounds.
  56. Yes, exactly. You know they're sleeping.
  57. They can't hear it.
  58. They wake up.
  59. They do better on those than the ones that you didn't play.
  60. That's amazing. Yeah, it's like magic.
  61. So Jude ran this experiment on 12 people, and the results were significant.
  62. So it's not that you remember things better.
  63. It's that you forget them less.
  64. Now I was a huge skeptic when I first heard that you can do better at a memory task just by playing sounds during sleep.
  65. But we replicated these experiments for ourselves.
  66. The facts and memories that we collect throughout the day are very fragile and they're easily lost and forgotten.
  67. But by reactivating them during sleep, even without us being aware,
  68. it seems like we can make them more stable and less prone to forgetting.
  69. Now that's pretty incredible.
  70. Our brains are still active even when we're not.
  71. So if you're like me and a bit forgetful,
  72. perhaps the solution is a pair of headphones and a soft couch.