back to indexUnderstand & Improve Memory Using Science-Based Tools | Huberman Lab Podcast #72
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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman,
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and I'm a professor of neurobiology and ophthalmology
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at Stanford School of Medicine.
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Today, we are discussing memory,
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in particular, how to improve your memory.
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Now, the study of memory is one that dates back
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many decades, and by now there's a pretty good understanding
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of how memories are formed in the brain,
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the different structures involved,
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and some of the neurochemicals involved.
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We will talk about some of that today.
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Often overlooked, however,
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is that memories are not just about learning.
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Memories are also about placing your entire life
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And that's because what's really special about the brain,
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and in particular, the human brain,
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is its ability to place events in the context
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of past events, the present, and future events,
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and sometimes even combinations of the past and present,
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or present and future, and so on.
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So when we talk about memory,
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what we're really talking about
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is how your immediate experiences
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relate to previous and future experiences.
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Today, I'm going to make clear how that process occurs.
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Even if you don't have a background in biology or psychology,
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I promise to put it into language
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that anyone can access and understand.
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And we are going to talk about the science
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that points to specific tools
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for enhancing learning and memory.
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We're also going to talk about unlearning and forgetting.
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There are, of course, instances
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in which we would like to forget things,
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and that too is a biological process
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for which great tools exist to, for instance,
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eliminate or at least reduce the emotional load
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of our previous experience that you really did not like,
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or that perhaps even was traumatic to you.
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So today, you're going to learn
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about the systems in the brain and body
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that establish memories.
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You're going to learn why certain memories
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are easier to form than others.
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And I'm going to talk about specific tools
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that are grounded in not just one,
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not just a dozen, but well over a hundred studies
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in animals and humans that point to specific protocols
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that you can use in order to stamp down
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learning of particular things more easily.
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And you can also leverage that same knowledge
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to better forget or unload the emotional weight
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of experiences that you did not like.
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We are also going to discuss topics like deja vu
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and photographic memory.
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And for those of you that do not have a photographic memory,
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and I should point out
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that I do not have a photographic memory either.
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Well, you will learn how to use your visual system
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in order to better learn visual and auditory information.
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There are protocols to do this
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grounded in excellent peer reviewed research.
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So while you may not have a true photographic memory,
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by the end of the episode, you will have tools in hand,
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or I should say tools in mind or in eyes and mind
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to be able to encode and remember specific events
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better than you would otherwise.
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Before we begin, I'd like to emphasize
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that this podcast is separate from my teaching
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and research roles at Stanford.
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It is however, part of my desire and effort
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to bring zero cost to consumer information
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about science and science related tools
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to the general public.
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In keeping with that theme,
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I'd like to thank the sponsors of today's podcast.
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Our first sponsor is Eight Sleep.
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with cooling, heating, and sleep tracking.
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Many times on this podcast,
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I've talked about the incredible relationship
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between temperature and sleep,
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as well as temperature and wakefulness.
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Many people aren't aware of this,
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but waking up in the morning is in part the consequence
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of your body heating up and falling asleep at night
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and remaining in deep sleep is in part the consequence
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of your body temperature dropping by one to three degrees.
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Eight Sleep mattress covers are terrific
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Today's episode is also brought to us by Thesis.
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I don't like the word nootropics,
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because nootropics means smart drugs,
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and there really isn't a neuroscience of smart.
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Of course, there is this notion of intelligence,
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but we now know there are lots of different forms
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Also, as a neuroscientist,
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we don't really think about intelligence,
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Okay, let's talk about memory
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and let's talk about how to get better
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at remembering things.
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Now, in order to address both of those things,
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we need to do a little bit of brain science 101 review.
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And I promise this will only take two minutes.
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And I promise that even if you don't have a background
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in biology, it will make sense.
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We are constantly being bombarded with physical stimuli,
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patterns of touch on our skin,
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light to our eyes,
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light to our skin for that matter,
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smells, tastes, and sound waves.
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In fact, if you can hear me saying this right now,
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well, that's the consequence of sound waves
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arriving into your ears through headphones,
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a computer, or some other speaker device.
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Each one of, and all of those sensory stimuli
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are converted into electricity and chemical signals
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by your so-called nervous system,
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your brain, your spinal cord,
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and all their connections with the organs of the body
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and all the connections of your organs of the body
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back to your brain and spinal cord.
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One of the primary jobs of your nervous system, in fact,
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is to convert physical events in the world
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that are non-negotiable, right?
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Photons of light are photons of light.
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Sound waves are sound waves.
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There's no changing that.
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But your nervous system does change that.
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It converts those things into electrical signals
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and chemical signals,
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which are the language of your nervous system.
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Now, just because you're being bombarded
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with all this sensory information
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and it's being converted into a language
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that neurons and the rest of your nervous system
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can understand does not mean that you are aware of it all.
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In fact, you are only going to perceive a small amount
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of that sensory information.
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For instance, if you can hear me speaking right now,
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you are perceiving my voice,
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but you are also most likely neglecting the feeling
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of the contact of your skin
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with whichever surface you happen to be sitting
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So it is only by perceiving a subset,
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a small fraction of the sensory events in our environment
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that we can make sense of the world around us.
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Otherwise we would just be overwhelmed
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with all the things that are happening
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in any one given moment.
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Now, memory is simply a bias in which perceptions
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will be replayed again in the future.
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Anytime you experience something,
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that is the consequence of specific chains of neurons
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that we call neural circuits being activated.
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And memory is simply a bias in the likelihood
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that that specific chain of neurons
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will be activated again.
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So for instance, if you can remember your name,
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and I certainly hope that you can,
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well, that means that there are specific chains of neurons
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in your brain that represent your name.
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And when those neurons connect with one another
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and communicate electrically with one another
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in a particular sequence, you remember your name.
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Were that particular chain of neurons to be disrupted,
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you would not be able to remember your name.
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Now, this might seem immensely simple,
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but it raises this really interesting question,
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which we talked about before,
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which is why do we remember certain things and not others?
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Because according to what I've just said,
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as you go through life,
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you're experiencing things all the time.
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You're constantly being bombarded with sensory stimuli.
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Some of those sensory stimuli you perceive,
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and only some of those perceptions
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get stamped down as memories.
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Today, I'm going to teach you
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how certain things get stamped down as memories.
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And I'm going to teach you how to leverage that process
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in order to remember the information that you want
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Now, even though I've told you that a memory
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is simply a bias in the likelihood
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that a particular chain of neurons will be activated
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in a particular sequence again and again,
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it doesn't operate on its own.
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In fact, most of what we remember
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takes place in a context of other events.
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So for instance, you can most likely remember your name,
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and yet you're probably not thinking about
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when it was that you first learned your name.
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This generally happens when we are very, very young children.
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And yet I'm guessing you could probably remember
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a time when someone mispronounced your name
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or made fun of your name,
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or as the case was for me,
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I got to the third grade and there were two Andrews.
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And sadly for me, I lost the coin flip
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that allowed me to keep Andrew.
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And from about third grade until about 12th grade,
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people called me Andy, which I really did not prefer.
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So if you call me Andy in the comments,
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I'll delete your comment.
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Just kidding, doesn't bother me that much.
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But eventually I reclaimed Andrew as my name.
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Well, it was mine to begin with and throughout,
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but I started going by Andrew again.
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Why do I say this?
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Well, there's a whole context to my name for me.
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And there may or may not be a whole context
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to your name for you,
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but presumably if you asked your parents
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why they named you your given name,
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you'll get a context, et cetera.
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That context reflects the activation
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of other neural circuits that are also related
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to other events in your life,
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not just your name, but probably your siblings names
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and who your parents are and on and on and on.
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And so the way memory works is that each individual thing
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that we remember or that we want to remember
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is linked to something by either a close,
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a medium or a very distant association.
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This turns out to be immensely important.
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I know many of you will read or will encounter programs
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that are designed to help you enhance your memory.
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You have these phenoms that can remember 50 names
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in a room full of people,
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or they can remember a bunch of names of novel objects
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or maybe even in different languages.
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And oftentimes that's done by association.
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So people will come up with little mental tricks
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to either link the sound of a word or the meaning of a word
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in some way that's meaningful for them
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and will enhance their memory.
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That can be done and is impressive when we see it.
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And for those of you who can do that, congratulations.
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Most of us can't do that,
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or at least it requires a lot of effort and training.
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However, there are things that we can do
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that leverage the natural biology of our nervous system
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to enhance learning and memory of particular perceptions
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and particular information.
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Let's first just talk about the most basic ways
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that we learn and remember things
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and how to improve learning and memory.
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And the most basic one is repetition.
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Now the study of memory and the role of repetition
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actually dates back to the late 1800s, early 1900s,
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when Ebbinghaus developed
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the first so-called learning curves.
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Now learning curves are simply what results
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when you quantify how many repetitions of something
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are required in order to remember something.
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In fact, it's been said that Ebbinghaus
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liberated the understanding of learning
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from the philosophers by generating these learning curves.
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What do you mean by that?
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Well, before Ebbinghaus came along,
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learning and memory were thought to be philosophical ideas.
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Ebbinghaus came along and said,
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well, let's actually take some measurements.
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Let's measure how well I can remember a sequence of words
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or a sequence of numbers if I just repeat them.
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So what Ebbinghaus did is he would take
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a sequence of numbers or words on a page
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and he would read them.
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And then he would take a separate sheet of paper
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and we have to presume he didn't cheat.
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And he would write down as many of them as he could
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and he would try and keep them in the same sequence.
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Then he would compare to the original list
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and he would see how many errors he made.
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And you do this over and over and over again.
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And as you would expect early in the training
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and the learning, it took a lot more repetitions
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to get the sequence correct.
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And over time, it took fewer sequences.
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And he referred to that difference
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in the initial number of repetitions
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that he had to perform versus the later number
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of repetitions that he had to perform
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as a so-called savings.
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So he literally thought of the brain
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as having to generate a kind of a currency of effort.
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And he talked about savings as the reduction
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in the amount of effort that he had to put forward
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in order to learn information.
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And what he got was a learning curve.
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And you can imagine what that learning curve looked like.
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It was at a very sharp peak at the beginning
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that dropped off over time.
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And of course he remembered all this meaningless information
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but even though the information might've been meaningless,
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the experiment itself and what Ebbinghaus demonstrated
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was immensely meaningful because what it said
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was that with repetition,
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we can activate particular sequences of neurons.
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And that repeated activation lays down
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what we call a memory.
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And that might all seem like a big duh,
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but prior to Ebbinghaus, none of that was known.
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Now I should also say Ebbinghaus,
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because of when he was alive,
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was not aware of these things that we call neural circuits.
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It was in 1906 that Golgi and Cajal got the Nobel prize
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for actually showing that neurons are independent cells
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connected by synapses,
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these little gaps between them where they communicate.
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So he may have been aware of that,
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but the whole notion of neural circuits
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hadn't really come about.
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Nevertheless, what the Ebbinghaus learning curves
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really established was that sheer repetition,
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just repeating things over and over and over again,
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is sufficient to learn.
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Something that no doubt had been observed before,
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but it had never been formally quantified.
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Now, if we look at that result,
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there's something really important
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that lies a little bit cryptic,
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that's not so obvious to most people,
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which is the information that he was trying to learn
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wasn't any more interesting the second time
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than it was the first,
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probably was even less interesting
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and less and less interesting with each repetition.
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And yet it was sheer repetition
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that allowed him to remember.
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Now, sometime later in the early to mid 1920s,
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a psychologist in Canada named Donald Hebb
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came up with what was called Hebb's postulate.
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And Hebb's postulate, broadly speaking,
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is this idea that if a sequence of neurons
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is active at the same time or at roughly the same time,
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that that would lead to a strengthening of the connections
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between those neurons.
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And many, many decades of experimentation later,
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we now know that postulate to be true.
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Neurons themselves are not smart.
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They don't have knowledge.
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So every memory is the consequence, as I told you before,
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of the repeated activation of a particular chain of neurons.
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And what Ebbinghaus showed through repetition
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and what Donald Hebb proposed and was eventually verified
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through experimentation on animals and humans
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was that if you encourage the co-activation of neurons,
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meaning have neurons fire at roughly the same time,
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they will strengthen their connections.
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It leads to a bias in the probability
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that those neurons will be active again.
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Now, this is vitally important
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because nowadays we hear a lot about
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how memories are the consequence
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of new neurons added in the brain,
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or that every time you learn something,
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a new connection in your brain forms.
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Well, sorry to break it to you,
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but that's simply not the case.
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Most of the time, and I want to emphasize most,
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not all, but most of the time when we learn something,
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it's because existing neurons, not new neurons,
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but existing neurons strengthen their connection
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through co-activation over and over and over
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through repetition, or, and this is a very important or,
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or through very strong activation once and only once.
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In fact, there's something called one trial learning
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whereby we experience something
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and we will remember that thing forever.
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This is often most associated with negative events,
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and I'll explain why in a few minutes,
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but it can also be associated with positive events,
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like the first time you saw your romantic partner
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or something that happened with that romantic partner,
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or the first time that you saw your child,
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or any other positive event,
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as well as any other extremely negative event.
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So again, both repetition and,
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I guess we could label it intensity,
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but what we really mean when we say intensity
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is strong activation of neurons can lay down these traces,
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these circuits that are far more likely to be active again,
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than had there not been repetition
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or not some strong activation of those circuits.
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So with that in mind,
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let's return to the original contrarian question
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that I raised before,
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which is why do we remember anything?
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Every day you wake up,
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your neurons in your brain and body are active,
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different neural circuits are active,
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and yet you only remember a small fraction
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of the things that happen each day,
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and yet you retain a lot of information from previous days
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and the days before those and so on.
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It is only with a lot of repetition
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or with extremely strong activation
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of a given neural circuit that we will create new memories.
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And so in a few minutes,
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I'll explain how to get extremely strong activation
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of particular neural circuits.
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Repetition is pretty obvious, repetition is repetition,
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but in a few minutes,
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I'll illustrate a whole set of experiments
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and a whole set of tools
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that point to how you can get extra strong activation
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of a given neural circuit as it relates to learning
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so that you will remember that information,
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perhaps not just with one trial of learning,
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but certainly with far fewer repetitions
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than would be required otherwise.
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Before we go any further,
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I want to preface the discussion by saying
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that there are a lot of different kinds of memory.
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In fact, were you to take a voyage into the neuroscience
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and or psychology of memory,
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you would find an immense number of different terms
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to describe the immense number of different types of memory
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that researchers focus on.
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But for sake of today's discussion,
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really just want to focus on short-term memory,
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medium-term memory, and long-term memory.
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And while there's still debate,
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as is always the case with scientists, frankly,
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about the exact divisions
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between short-term, medium, and long-term memory,
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we can broadly define short-term memory and long-term memory
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and we can describe a couple of different types of those
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that I think you can relate to in your everyday life.
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The most common form of short-term memory
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that we're going to focus on is called working memory.
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Working memory is your ability to keep a chain of numbers
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in mind for some period of time,
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but the expectation really isn't
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that you would remember those numbers the next day
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and certainly not the next week.
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So a good example would be a phone number.
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If I were to tell you a phone number, 493-2938,
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well, you could probably remember it, 493-2938.
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But if I came back tomorrow and asked you
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to repeat that chain of numbers, most likely you would not,
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unless of course we used a particular tool
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to stamp down that memory into your mind
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and commit it to long-term memory.
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Now, of course, in this day and age,
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most people have phone numbers programmed into their phone.
link |
They don't really have to remember the exact numbers.
link |
It's usually done by contact identity and so forth.
link |
So a different example
link |
that some of you are probably more familiar with
link |
would be those security codes.
link |
So you try and log on to an app or a website
link |
and it asks you for a security code
link |
that's been sent to your text messages,
link |
and then you can either plug that in directly in some cases,
link |
or you have to remember that short sequence
link |
of anywhere usually from six to seven,
link |
sometimes eight numbers.
link |
Your ability to do that, to switch back and forth
link |
between web pages or apps and plug in that number
link |
by remembering the sequence and plugging it in
link |
by texting or keying it in on your keyboard,
link |
that's a really good example of working memory.
link |
Long-term memory of the sort
link |
that we're going to be talking a lot about today
link |
is your ability to commit certain patterns of information,
link |
either cognitive information or motor information, right?
link |
The ability to move your limbs in a particular sequence
link |
over long periods of time,
link |
such that you could remember it a day or a week or a month,
link |
or maybe even a year or several years later.
link |
So we've got short-term memory and long-term memory,
link |
and we've got this working memory,
link |
which is kind of keeping something online,
link |
but then discarding it, okay?
link |
Not online on a computer, but online within your brain.
link |
There are also two major categories of memory
link |
that I'd like you to know about.
link |
One is explicit memory.
link |
So this is not necessarily explicit of the sort
link |
that you're used to thinking about,
link |
but rather the fact that you can declare you know something.
link |
So you have an explicit memory of your name.
link |
Presumably you have an explicit memory
link |
of the house or the apartment that you grew up in.
link |
You know something and you know you know it,
link |
and you can declare it.
link |
what was the color of the first car that you owned?
link |
Or what is the color of your romantic partner's hair?
link |
These sorts of things.
link |
That's an explicit declarative memory,
link |
but you also have explicit procedural memories.
link |
Now, procedural memories, as the name suggests,
link |
involve action sequences.
link |
The simplest one, it's almost ridiculously simple,
link |
If I say, how is it that you walk from one room
link |
to the other, you'd probably say,
link |
well, I go that direction, then I turn left.
link |
I say, no, no, no, no.
link |
How is it exactly that you do it?
link |
And say, well, I move my left foot,
link |
then my right foot, then my left foot.
link |
And you could describe that.
link |
So it's an explicit procedural memory.
link |
So much so that if you were going to teach a young toddler
link |
how to walk, you would probably say,
link |
okay, good, good, try.
link |
Okay, and you, you know,
link |
probably that's going to be pre-language for the toddler,
link |
but you're going to encourage them to move one leg
link |
And you're going to encourage and reward them
link |
for moving one leg than the other,
link |
because you have an explicit procedural memory
link |
of how to walk, okay?
link |
Almost ridiculously simple,
link |
maybe even truly ridiculously simple.
link |
But nonetheless, when you think about it
link |
in the context of neural circuits and neural firing,
link |
Even more amazing is the fact that all explicit memories,
link |
both declarative and procedural explicit memories,
link |
can be moved from explicit to implicit.
link |
What do I mean by that?
link |
Well, in the example of walking,
link |
you might've chuckled a little bit
link |
or kind of shook your head and said,
link |
that's a ridiculous thing to ask.
link |
How do I walk from one room to the next?
link |
I just walk, I just do it.
link |
Ah, well, what is just do it?
link |
What it is is that you have an implicit understanding,
link |
meaning your nervous system knows how to walk
link |
without you actually having to think about
link |
what you know about how to walk.
link |
You just get up out of your chair
link |
or you get up out of bed and you walk.
link |
In the brain, you have a structure.
link |
In fact, you have one on each side of your brain.
link |
It's called the hippocampus.
link |
The hippocampus literally means seahorse.
link |
Anatomists like to name brain structures after things
link |
that they think those brain structures resemble.
link |
When I look at the hippocampus,
link |
frankly, it doesn't look like a seahorse,
link |
which either reflects my lack of understanding
link |
of what a seahorse really looks like, a visual deficit,
link |
or I think it's fair to say that those anatomists
link |
were using a little bit of creative elaboration
link |
when thinking about what the hippocampus looks like.
link |
Nonetheless, it is a curved structure.
link |
It has many layers.
link |
It's been described by my colleague, Robert Sapolsky,
link |
and by others as looking more like a jelly roll
link |
or a cinnamon roll is what it looks like to me.
link |
And if you were to take one cinnamon roll,
link |
chop it down the middle.
link |
So now you've got two half cinnamon rolls
link |
and rather than put them back together
link |
in the configuration they were before,
link |
you just slide one down
link |
so that you've got essentially two C's,
link |
two C-shaped halves of the cinnamon roll
link |
and you push them together,
link |
slightly offset from one another.
link |
Well, that's what the hippocampus looks like to me.
link |
And I think that's a far better description
link |
of its actual physical structure.
link |
But I guess if you were to use that physical structure
link |
as the name, well, then you'd have to open up
link |
a brain atlas and it would be called
link |
two half C cinnamon rolls stuffed halfway together.
link |
So that's not very good.
link |
So I guess seahorse will work.
link |
Hippocampus is the name of this structure
link |
and it is the site in your brain.
link |
And again, you have one on each side of your brain
link |
in which explicit declarative memories are formed.
link |
It is not where those memories are stored and maintained.
link |
It is where they are established in the first place.
link |
In contrast, implicit memories, right?
link |
These subconscious memories are formed
link |
and stored elsewhere in the brain,
link |
mainly by areas like the cerebellum,
link |
but also the neocortex,
link |
the kind of outer shell of your brain.
link |
The cerebellum is, it literally means mini brain.
link |
And it does in fact look like a mini brain
link |
and is in the back of the brain.
link |
And the neocortex is the outer part of the brain
link |
that covers all the other stuff.
link |
So the hippocampus is vitally important
link |
for establishing these new declarative memories
link |
of what you know and what you know how to do.
link |
Now, in order to really understand
link |
the role of the hippocampus in memory,
link |
in particular explicit declarative
link |
and explicit procedural memory,
link |
and to really understand how that's distinct
link |
from implicit declarative and implicit procedural memories,
link |
we have to look to a clinical case.
link |
And the clinical case that I'm referring to
link |
is a patient who went by the name HM.
link |
Patients go by their initials
link |
in order to maintain confidentiality of their real identity.
link |
HM had what's called intractable epilepsy.
link |
So he would have these really dramatic
link |
so-called grand mal seizures or drop seizures.
link |
For those of you that know somebody with epilepsy
link |
or that have epilepsy, you might be familiar with this.
link |
You can have petite mal seizures, which are minor seizures.
link |
You can have tonic-clonic seizures,
link |
which are sometimes not even detectable.
link |
You can have absent seizures where people will just stop.
link |
It's almost as if their brain goes on pause
link |
and they'll just stop there.
link |
It was reported actually that Einstein had absent seizures,
link |
although I don't know that
link |
that's ever really been confirmed neurologically.
link |
Grand mal seizures are extremely severe
link |
and that's what HM had.
link |
So he could just be going about his day
link |
and maybe even cooking or doing something, driving,
link |
operating any kind of machinery,
link |
and then all of a sudden he would just have a drop seizure
link |
so he would just physically drop
link |
and go into a grand mal seizure.
link |
So convulsing of the whole body,
link |
loss of consciousness, et cetera.
link |
Or he would feel it coming on.
link |
Oftentimes people with epilepsy
link |
can feel the epilepsy seizure coming on
link |
kind of like a wave from the back of the brain.
link |
And sometimes they can get to a safe circumstance,
link |
And so the frequency and the intensity of his seizures
link |
were so robust that the neurosurgeons and neurologists
link |
decided that they needed to locate the origin,
link |
what they call the foci of those seizures
link |
and remove that brain tissue
link |
because the way seizures work is they spread out
link |
from that focus or that foci of brain tissue.
link |
And unfortunately for HM,
link |
the focus of his seizures was the hippocampus.
link |
So after a lot of deliberation, a neurosurgeon,
link |
in fact, one of the most famous neurosurgeons
link |
in the world at that time
link |
made what are called electrolytic lesions,
link |
actually burned out the hippocampus in the brain of HM.
link |
And as a consequence, he lost all explicit memory.
link |
Now, the consequence of this was that he couldn't exist
link |
in normal, everyday life, like most people.
link |
So he had to live mostly, not entirely,
link |
but mostly in a kind of hospital setting.
link |
And I've talked to several people who have,
link |
who I should say, who met HM directly
link |
because he's no longer alive,
link |
but an interaction with him might look like the following.
link |
He would walk up to you just fine.
link |
You wouldn't know that he had any kind of brain damage.
link |
He could walk fine.
link |
He could speak fine.
link |
And he'd say, hi, I'm Andrew.
link |
And he'd say, hi, I'm whatever his name happened to be.
link |
He wouldn't say HM, but he'd probably say his real name.
link |
And then perhaps someone new would walk into the room.
link |
He might turn around, look at that person
link |
as any of us might do,
link |
then turn around back to me and say,
link |
hi, what's your name?
link |
And if I were to say, well, I just told you my name
link |
and you just told me your name, do you remember that?
link |
He'd say, I'm sorry, I don't remember any of that.
link |
So you had to go through this over and over again.
link |
So a complete lack of explicit declarative memory.
link |
Now, he did have some memory for previous events
link |
in his life that dated way back, okay?
link |
Again, hinting at the idea that memories
link |
are not necessarily stored in the hippocampus.
link |
They're just formed in the hippocampus.
link |
So once they've moved out of the hippocampus
link |
to other brain areas, he could still keep those memories.
link |
They're in a different database, if you will.
link |
They're in a different pattern of firing
link |
of other neural circuits, but he couldn't form new memories.
link |
Now there's some very important and interesting twists
link |
on what HM could and could not do
link |
in terms of learning and memory
link |
that teach us a lot about the brain.
link |
In fact, I think most neuroscientists would agree
link |
that this unfortunate case of HM's epilepsy
link |
and the subsequent neurosurgery that he had
link |
taught us much of what we know, or at least think about
link |
in terms of human learning and memory.
link |
For instance, as I mentioned before,
link |
he still had implicit knowledge.
link |
He knew how to walk.
link |
He knew how to do certain things like make a cup of coffee.
link |
He knew the names of people that he had met
link |
much earlier in his life and so on.
link |
And yet he couldn't form new memories.
link |
Now, in violation to that last statement,
link |
there were some elements of HM's emotionality
link |
that suggests that there was some sort of residual capacity
link |
to learn new information,
link |
but it wasn't what we normally think of
link |
as explicit declarative or procedural memory.
link |
For instance, it's been reported,
link |
or it's been said, I should say,
link |
because I don't know that the studies were ever done
link |
with intense physiological measurements,
link |
that if you were to tell HM a joke
link |
and he thought it was funny, he would laugh really hard.
link |
Though he liked jokes, so you'd tell him,
link |
you'd say, HM, I want to tell you a joke.
link |
You tell him a joke and he'd laugh really hard.
link |
Then you could leave the room, come back,
link |
and tell him the same joke again.
link |
Now, keep in mind, he did not remember
link |
that you told him the joke previously.
link |
And the second time he would laugh a little bit less.
link |
And then you'd leave the room, come back again,
link |
say, hi, I'm Andrew.
link |
And he'd say, oh, nice to meet you,
link |
because as you recall,
link |
because you can recall things,
link |
but he couldn't recall things.
link |
He didn't know that he just met you,
link |
or at least he couldn't remember it.
link |
You tell him the joke a third time or a fourth time.
link |
And with each subsequent telling of the joke,
link |
he found it a little less funny,
link |
just as, keep this in mind, folks,
link |
if you tell a joke and you get a big laugh,
link |
don't tell it again, at least not immediately,
link |
not to the same person or the same crowd,
link |
because the second time it's a little less funny,
link |
and the third time it's a little less funny.
link |
And that actually has to do with a whole element
link |
of dopamine and its relationship to surprise.
link |
And that's the topic of a future podcast
link |
where we talk all about humor and novelty in the brain.
link |
But the point being that certain forms of memory
link |
seem to exist in a kind of phantom-like way
link |
within HM's brain.
link |
What do I mean by that?
link |
Well, this underscores the fact that he had
link |
an implicit memory of having heard the joke before.
link |
And it suggests that humor, or at least what we find funny,
link |
is somehow more related to procedures,
link |
similar to walking or motor ability,
link |
than it is to the precise content of that joke.
link |
That's a little bit of an abstract concept,
link |
but the point is that HM lacked explicit declarative memory.
link |
He couldn't tell you what he had just heard.
link |
He could not learn new information.
link |
And he couldn't tell you how to do something
link |
unless he had learned how to do that something
link |
Now, there've been a lot of other patients besides HM
link |
that have had brain lesions due to epilepsy,
link |
or I should say, due to surgeries to treat epilepsy,
link |
due to strokes, due to sadly gunshot wounds
link |
and other forms of what we call infarct,
link |
infarct, I-N-F-A-R-C-T, infarct,
link |
is the word we use to describe damage
link |
to a particular brain region.
link |
And many different patients with many different patterns
link |
of infarct have taught us a lot about how memory
link |
and other aspects of the brain work.
link |
HM really teaches us that what we know
link |
and what we are able to do is the consequence of things
link |
that we are aware of and learnings that have been passed off
link |
into subconscious knowledge, that our body knows,
link |
our brain knows, but we don't know exactly
link |
how we know that thing.
link |
And I tell you the story about HM's ability
link |
to understand a joke,
link |
but that with repeated telling of a joke,
link |
it has less and less and less of an impact
link |
in creating a sense of laughter, of humor in HM,
link |
not as just an anecdote to flesh out his story,
link |
but because emotion itself turns out to be the way
link |
in which we can enhance memories,
link |
even if those are memories for things that are not funny,
link |
are not intensely sad, are not immensely happy,
link |
or don't evoke a really strong emotional response
link |
or even any emotional response.
link |
And the reason for that is that emotions,
link |
just like perception, just like sensation,
link |
are the consequence of particular neurochemicals
link |
being present in our brain and body.
link |
And as I'm going to tell you next,
link |
there are particular neurochemicals
link |
that you can leverage in order
link |
to learn specific information faster
link |
and to remember it for a much longer period of time,
link |
maybe even forever.
link |
And you can do that by leveraging the relationship
link |
in your nervous system between your brain and your body
link |
and your body back to your brain.
link |
So let's talk about tools for enhancing memory.
link |
Now there's one tool that is absolutely clear works,
link |
and it's always worked, it works now,
link |
and it will work forever.
link |
And that's repetition.
link |
The more often that you perform something
link |
or that you recite something,
link |
the more likely you are to remember it in the future.
link |
And while that might seem obvious,
link |
it's worth thinking about what's happening
link |
when you repeat something.
link |
But when I say what's happening, I mean at the neural level.
link |
What's happening is that you're encouraging the firing
link |
of particular chains of neurons
link |
that reside in a particular circuit, right?
link |
So a particular sequence of neurons playing neuron A, B, C, D
link |
played in that particular sequence over and over
link |
and over again, and with more repetitions,
link |
you get more strengthening of those nerve connections.
link |
Now, repetition works, but the problem for most people
link |
is that they either don't have the patience,
link |
they don't have the time,
link |
and sometimes they literally don't have the time
link |
because they've got a deadline on something
link |
that they're trying to remember and learn,
link |
or they simply would like to be able
link |
to remember things better in general,
link |
remember them more quickly.
link |
This process of accelerating repetition-based learning
link |
so that your learning curve doesn't go
link |
from having to perform something 1,000 times
link |
and then gradually over time, it's 1,750 times a day,
link |
500 times a day, 300 times a day,
link |
and down to no repetitions, right?
link |
You can just perform that thing
link |
the first time and every time.
link |
Well, there is a way to shift that curve
link |
so that you can essentially establish stronger connections
link |
between the neurons that are involved
link |
in generating that memory or behavior more quickly.
link |
How do you do that?
link |
Well, in order to answer that,
link |
we have to look at the beautiful work
link |
of James McGaugh and Larry Cahill.
link |
James McGaugh and Larry Cahill did a number of experiments
link |
over several decades, really,
link |
based on a lot of animal literature,
link |
but mainly focused on humans that really established
link |
what's required to get better at remembering things
link |
and to do so very quickly.
link |
I want to talk about one experiment that they did
link |
that was particularly important,
link |
and we will provide a link to this paper.
link |
It's some years old now, but the results still hold up.
link |
In fact, the results establish an entire field of memory
link |
in neuroscience and psychology.
link |
What they did is they had human subjects
link |
come into the laboratory and to read a short paragraph
link |
of about 12 sentences,
link |
and the key thing is that some subjects read a paragraph
link |
that was pretty mundane.
link |
The content, the information within the paragraph
link |
was all related to the content of the previous sentence,
link |
so it was a cogent paragraph, right?
link |
It just wasn't meaningless scramble of words,
link |
but it described a kind of mundane set of circumstances.
link |
Maybe it would be a story about someone who walked
link |
into a room, sat down at a desk, wrote for a little bit,
link |
then got up and had lunch,
link |
just kind of mundane information, not very interesting.
link |
Another group of subjects read also a 12 sentence paragraph,
link |
but that paragraph included a subset of sentences
link |
that had a lot of emotionally intense language,
link |
or that had language that could evoke
link |
an emotionally intense response in the person reading it.
link |
So it might've talked about a car accident
link |
or a very intense surgery,
link |
but it also could be positive stuff,
link |
things like a birthday party
link |
or a celebration of some other kind or a big sports win.
link |
So in other words, you have two conditions of this study.
link |
People either read a boring paragraph
link |
or they read a really emotionally laden paragraph.
link |
And again, the emotions could either be positive
link |
or negative emotions.
link |
Subjects left the laboratory and sometime later,
link |
they were called back to the laboratory.
link |
And I should say at no point in the experiment
link |
did they know they were part of a memory experiment, okay?
link |
They don't know why they're reading this paragraph.
link |
They came in either for class credit or to get paid.
link |
It's typically how these things are done
link |
on college campuses or elsewhere.
link |
They come back into the lab and they would get a pop quiz.
link |
They would be asked to recall the content of the paragraph
link |
that they had read previously.
link |
As is probably expected, perhaps even obvious to you,
link |
the subjects that read the emotionally intense paragraph
link |
remembered far more of the content of that paragraph
link |
and were far more accurate
link |
in their remembering of that information.
link |
Now, that particular finding wasn't very novel.
link |
Many people had previously described
link |
how emotionally intense events are better remembered
link |
than non emotionally intense events.
link |
In fact, way back in the 1600s, Francis Bacon,
link |
who's largely credited with developing the scientific method
link |
said, quote, memory is assisted by anything
link |
that makes an impression on a powerful passion,
link |
inspiring fear, for example, or wonder, shame, or joy.
link |
Francis Bacon said that in 1620.
link |
So Jim McGaugh and Larry Cahill
link |
were certainly not the first to demonstrate
link |
or to conceive of the idea
link |
that emotionally laden experiences
link |
are more easily remembered than other experiences.
link |
However, what they did next was immensely important
link |
for our understanding of memory
link |
and for our building of tools
link |
to enhance learning and memory.
link |
What they did was they evaluated the capacity for stress
link |
and for particular neurochemicals associated with stress
link |
to improve our ability to learn information,
link |
not just information that is emotional,
link |
but information of all kinds.
link |
So I'm going to describe some experiments
link |
done in animal models just very briefly,
link |
and then experiments done on human subjects,
link |
because McGaugh worked mainly on animals,
link |
also human subjects,
link |
Larry Cahill almost exclusively on human subjects.
link |
If you take a rat or a mouse and put it in an arena
link |
where at one location,
link |
the animal receives an electrical shock,
link |
and then you come back the next day,
link |
you remove the shock evoking device,
link |
and you let the animal move around that arena,
link |
that animal will quite understandably avoid the location
link |
where it was shocked, so-called conditioned place aversion.
link |
That effect of avoiding that particular location
link |
occurs in one trial.
link |
That's a good example of one trial learning.
link |
So somehow the animal knows
link |
that it was shocked at that location.
link |
It remembers that it is a hippocampal dependent learning.
link |
So animals that lack a hippocampus
link |
or who have their hippocampus pharmacologically
link |
or otherwise incapacitated
link |
will not learn that new bit of information.
link |
But for animals that do,
link |
they remember it after the first time and every time,
link |
unless you are to block the release of certain chemicals
link |
in the brain and body,
link |
and the chemicals I'm referring to are epinephrine,
link |
adrenaline, and to some extent, the corticosterones,
link |
things like cortisol.
link |
Now we know that the effect of getting one trial learning
link |
somehow involves epinephrine,
link |
at least in this particular experimental scenario,
link |
because if researchers do the exact same experiment,
link |
and they have done the exact same experiment,
link |
but they introduce a pharmacological blocker of epinephrine
link |
so that epinephrine is released in response to the shock,
link |
but it cannot actually bind to its receptors
link |
and have all of its biological effects,
link |
well, then the animal is perfectly happy to tread back
link |
into the area where it received the shock.
link |
It's almost as if it didn't know,
link |
or we have to assume it didn't remember
link |
that it received the shock at that location.
link |
So it all seems pretty obvious when you hear it,
link |
something bad happens in a location,
link |
you'll go back to that location.
link |
So that's conditioned place avoidance,
link |
but it turns out that the opposite is also true,
link |
meaning for something called conditioned place preference,
link |
you can take an animal, put it into an arena,
link |
feed it or reward it somehow at one location in that arena.
link |
So you can give a hungry rat or mouse food
link |
at one particular location, take the animal out,
link |
come back the next day, no food is introduced,
link |
but it'll go back to the location where it received the food
link |
or you can do any variant of this.
link |
You can make the arena a little bit chilly
link |
and provide warmth at that location,
link |
or you can take a male animal and turns out male rats
link |
and mice will mate at any point or a female animal
link |
that's at the particular so-called receptive phase
link |
of her mating cycle and give them an opportunity
link |
to mate at a given location.
link |
They'll go back to that location and wait and wait.
link |
This is perhaps why people go back to the same bar,
link |
the bar, seat at the bar or the same restaurant
link |
and wait because of the one time they,
link |
things worked out for them, whatever the context was.
link |
Conditioned place preference.
link |
Conditioned place preference as with conditioned place
link |
avoidance depends on the release of adrenaline, right?
link |
It's not just about stress.
link |
It's about a heightened emotional state
link |
in the brain and body, okay?
link |
This is really important.
link |
It's not just about stress.
link |
You can get one trial learning for positive events,
link |
conditioned place preference,
link |
and you can get one trial learning for negative events.
link |
Here I say positive, negative.
link |
I'm putting what's called valence on.
link |
I'm making a value judgment
link |
about whether or not the animal liked it or didn't like it.
link |
And we have to presume what the animal liked or didn't like
link |
but this turns out all to be true for humans as well.
link |
We know that because McGaugh and Cahill did experiments
link |
where they gave people a boring paragraph to read
link |
and only a boring paragraph to read.
link |
But one group of subjects was asked to read the paragraph
link |
and then to place their arm into very, very cold water.
link |
In fact, it was ice water.
link |
We know that placing one's arm into ice water,
link |
especially if it's up to the shoulder or near to it,
link |
evokes the release of adrenaline in the body.
link |
It's not an enormous release,
link |
but it's a significant increase.
link |
And yes, they measured adrenaline release.
link |
they also measured for things like cortisol, et cetera.
link |
And what they found is that if one evokes the release
link |
of adrenaline through this arm into ice water approach,
link |
the information that they read previously,
link |
just a few minutes before, was remembered.
link |
It was retained as well as emotionally intense information.
link |
But keep in mind that information that they read
link |
was not interesting at all,
link |
or at least it wasn't emotionally laden.
link |
This had to be the effect of adrenaline released
link |
into the brain and body,
link |
because if they blocked the release or the function
link |
of adrenaline in the brain and or body,
link |
they could block this effect.
link |
Now, the biology of epinephrine and cortisol
link |
are a little bit complex,
link |
but there's some nuance there that's actually interesting
link |
and important to us.
link |
First of all, adrenaline is released in the body
link |
It's released in the body from the adrenals.
link |
Remember epinephrine and adrenaline are the same thing.
link |
Cortisol is also released from the adrenal glands,
link |
these two little glands that ride atop our kidneys,
link |
but it can't cross into the brain.
link |
It only has what we call peripheral effects,
link |
quickening of the heart rate, right?
link |
Changes the patterns of blood flow,
link |
changes our patterns of breathing,
link |
in general makes our breathing more shallow and faster,
link |
in general makes our heartbeat more quickly, et cetera.
link |
we have a little brain area called locus coeruleus,
link |
which is in the back of the brain,
link |
which has the opportunity to sprinkler the rest of the brain
link |
with the neuromodulator epinephrine, adrenaline,
link |
as well as norepinephrine, a related neuromodulator,
link |
and to essentially wake up or create a state of alertness
link |
throughout the brain.
link |
So it's a very general effect.
link |
The reason we have two sites of release
link |
is because these neurochemicals
link |
do not cross the blood brain barrier.
link |
And so waking up the body with adrenaline
link |
and waking up the brain are two separate
link |
so-called parallel phenomenon.
link |
Cortisol can cross the blood brain barrier
link |
because it's lipophilic,
link |
meaning it can move through fatty tissue.
link |
And we'll get into the biology of that in another episode,
link |
but cortisol in general is released
link |
and has much longer term effects.
link |
And as I've just told you can permeate
link |
throughout the brain and body,
link |
adrenaline has more local effects
link |
or at least a segregated between the brain and the body.
link |
This will turn out to be important later.
link |
The important thing to keep in mind
link |
is that it is the emotionality evoked by an experience,
link |
or to be more precise,
link |
it is the emotional state that you were in
link |
after you experienced something
link |
that dictates whether or not
link |
you will learn it quickly or not.
link |
This is absolutely important
link |
in terms of thinking about tools to improve your memory.
link |
And no, I am not going to suggest
link |
that every time you want to learn something,
link |
you plunge your arm into ice water.
link |
Why won't I suggest that?
link |
Well, it will induce the release of adrenaline,
link |
but there are better ways to get that adrenaline release.
link |
Before I explain exactly what those tools are,
link |
I want to tamp down the biology of how all this works,
link |
because in that understanding,
link |
you will have access to the best possible tools
link |
to improve your memory.
link |
First of all, McGaugh and Cahill
link |
were excellent experimentalists.
link |
They did not just establish that you could quicken
link |
the formation of a memory by accessing material
link |
that was very emotionally laden
link |
or creating an emotional high adrenaline state
link |
after interacting with some thing,
link |
some word, some person, some information.
link |
They also tested whether or not that whole effect
link |
could be blocked by blocking the emotional state
link |
or by blocking adrenaline.
link |
So what they did is they had people read paragraphs
link |
that either had a lot of emotional content
link |
or they had people read paragraphs that were pretty boring,
link |
but then had them put their arm into ice water.
link |
And I should say they did other experiments too,
link |
to increase adrenaline.
link |
There are even some shock experiments
link |
that were done by other groups,
link |
any number of things to evoke the release of adrenaline,
link |
even people taking drugs that increase adrenaline.
link |
But then they also did what are called blocking experiments.
link |
They did experiments where they had people
link |
get into a highly emotional state
link |
from reading highly emotional material
link |
or they got people to get into
link |
a highly emotional neurochemical state
link |
by reading boring material
link |
and then taking a drug to increase adrenaline
link |
or ice bath or a shock.
link |
And then they also administered a drug
link |
called a beta blocker to block the effect of adrenaline
link |
and related chemicals in the brain and body.
link |
And what they found is that even if people were exposed
link |
to something really emotional
link |
or had a lot of adrenaline in their system
link |
because they received a drug
link |
to increase the amount of adrenaline,
link |
two manipulations that normally would increase memory,
link |
keep that in mind,
link |
if they gave them a beta blocker,
link |
which reduced the response to that adrenaline, right?
link |
So no quickening of the heart rate,
link |
no quickening of the breathing,
link |
no increase in the activity of locus coeruleus
link |
and these kind of wake up signals to the rest of the brain.
link |
Well, then the material wasn't remembered better at all.
link |
What this tells us is that,
link |
yes, Francis Bacon was right, McGaugh and Cahill were right.
link |
Hundreds, if not thousands of philosophers
link |
and psychologists and neuroscientists
link |
were right in stating and in thinking
link |
that high emotional states help you learn things.
link |
But what McGaugh and Cahill really showed
link |
and what's most important to know
link |
is that it is the presence of high adrenaline,
link |
high amounts of norepinephrine and epinephrine
link |
and perhaps cortisol as well, as you'll soon see,
link |
that allows a memory to be stamped down quickly.
link |
It is not the emotion.
link |
It is the neurochemical state that you go into
link |
as a consequence of the emotion.
link |
And it's very important to understand
link |
that while those two things are related,
link |
they are not one and the same thing.
link |
Because what that means is that were you to evoke
link |
the release of epinephrine, norepinephrine and cortisol,
link |
or even just one or two of those chemicals,
link |
after experiencing something,
link |
you are stamping down the experience
link |
that you just previously had.
link |
This is fundamentally important and far and away different
link |
than the idea that we remember things
link |
because they're important to us
link |
or because they evoke emotion.
link |
That's true, but the real reason, the neurochemical reason,
link |
the mechanism behind all that is these neurochemicals
link |
have the ability to strengthen neural connections
link |
by making them active just once.
link |
There's something truly magic about
link |
that neurochemical cocktail
link |
that removes the need for repetition.
link |
Okay, so let's apply this knowledge.
link |
Let's establish a scientifically grounded set of tools,
link |
meaning tools that take into account
link |
the identity of the neurochemicals
link |
that are important for enhancing learning
link |
and the timing of the release of those chemicals
link |
in order to enhance learning.
link |
When I first learned about the results of McGaugh and Cahill,
link |
I was just blown away.
link |
I was also pretty upset, but not with them.
link |
I was upset with myself because I realized
link |
that the way that I'd been approaching learning and memory
link |
In fact, it was probably in the opposite direction
link |
to the enhanced protocol for learning and memory
link |
that I'm going to teach you today.
link |
My typical mode of trying to learn something
link |
while I was in college or while I was in graduate school
link |
or as a junior professor or even a tenured professor
link |
was to sit down to whatever it is
link |
I was going to try and learn, perhaps even memorize,
link |
or if it was a physical skill,
link |
move to whatever environment
link |
I was going to learn that physical skill in.
link |
And prior to that, to make sure that I was hydrated
link |
because that's important to me
link |
and certainly can contribute
link |
to your brain's ability to function
link |
and your body's ability to function
link |
and general patterns of alertness, but also to caffeinate.
link |
I would have a nice strong cup of coffee or espresso.
link |
I would have a nice strong cup of yerba mate.
link |
And I still drink coffee or yerba mate very regularly.
link |
I drink them in moderation, I think, certainly for me,
link |
but typically I would drink those things
link |
before I would engage in any kind of attempt
link |
to learn or memorize or to acquire a new skill.
link |
Now, caffeine in the form of coffee or yerba mate
link |
or any other form of caffeine
link |
does create a sense of alertness in our brain and body.
link |
And it does that through two major mechanisms.
link |
The first mechanism is by blocking the effects of adenosine.
link |
Adenosine is a molecule that builds up in the brain and body
link |
the longer that we are awake.
link |
And it's largely what's responsible
link |
for our feelings of sleepiness and fatigue
link |
when we've been awake for a very long time.
link |
Caffeine essentially acts to block the effects of adenosine.
link |
It's a competing agonist, not to get technical,
link |
but it binds to the receptor for adenosine
link |
for some period of time and prevents adenosine
link |
from having its normal pattern of action
link |
and thereby reduces our feelings of fatigue.
link |
But it also increases state of alertness.
link |
So while it's reducing fatigue,
link |
it's also pushing on neurochemical systems
link |
in order to directly increase our alertness.
link |
And it does that in large part
link |
by increasing the transmission of epinephrine,
link |
adrenaline in the brain and body.
link |
It also has this interesting effect
link |
of upregulating the number and or efficiency,
link |
or we say the efficacy of dopamine receptors
link |
such that when dopamine is present
link |
and as a molecule that increases motivation
link |
and craving and pursuit,
link |
that dopamine can have a more potent effect
link |
than it would otherwise.
link |
So caffeine really hits these three systems.
link |
It hits other systems too,
link |
but it mainly reduces fatigue by reducing adenosine,
link |
increases alertness by increasing epinephrine release
link |
or adrenaline release, I should say,
link |
both from the adrenals in your body
link |
and from locus coeruleus within the brain.
link |
And it can in parallel to all that increase the action
link |
or the efficacy of the action of dopamine.
link |
So my typical way of approaching learning and memory
link |
would be to drink some caffeine
link |
and then focus really hard on whatever it is
link |
that I'm trying to learn,
link |
trying to eliminate distractions,
link |
and then hope, hope, hope,
link |
or try, try, try to remember that information
link |
as best as I could.
link |
And frankly, I felt like it was working pretty well for me.
link |
And typically if I leveraged other forms of pharmacology
link |
in order to enhance learning and memory,
link |
things like alpha GPC or phosphatidylserine,
link |
I would do that by taking those things
link |
before I sat down to learn a particular set of information
link |
or before I went off to learn a particular physical skill.
link |
Now, for those of you out there listening to this,
link |
you're probably thinking, well, okay,
link |
the results of McGaugh and Cahill pointed to the fact
link |
that having adrenaline released after learning something
link |
enhanced learning of that thing.
link |
But a lot of these things like caffeine or alpha GPC
link |
can increase epinephrine and adrenaline or dopamine
link |
or other molecules in the brain and body
link |
that can enhance memory for a long period of time.
link |
So it makes sense to take it first or even during learning
link |
and then allow that increase to occur
link |
and the increase will occur over a long period of time
link |
and will enhance learning and memory.
link |
And while that is partially true, it is not entirely true.
link |
And it turns out it's not optimal.
link |
Work that was done by the McGaugh laboratory
link |
and other laboratories evaluated
link |
the precise temporal relationship
link |
between neurochemical activation of these pathways
link |
and learning and memory.
link |
What they did is they had animals and or people,
link |
depending on the experiment, take a drug, could be caffeine,
link |
could be in pill form,
link |
something that would increase adrenaline
link |
or related molecules that create the state of alertness
link |
that are related to emotionality.
link |
And they had them do it either an hour before,
link |
30 minutes before, 10 minutes before,
link |
five minutes before learning
link |
or during the bout of learning, right?
link |
The reading of the information or the performing
link |
of the skill that one is trying to learn
link |
or five minutes, 10 minutes, 15 minutes,
link |
30 minutes, et cetera, afterwards.
link |
So they looked very precisely at when exactly is best
link |
to evoke this adrenaline release.
link |
And it turns out that the best time window
link |
to evoke the release of these chemicals,
link |
if the goal is to enhance learning and memory
link |
of the material is either immediately after
link |
or just a few minutes, five, 10, maybe 15 minutes
link |
after you're repeating that information,
link |
you're trying to learn that information.
link |
Again, this could be cognitive information
link |
or this could be a physical skill.
link |
Now, this really spits in the face of the way
link |
that most of us approach learning and memory.
link |
Most of us, if we use stimulants like caffeine or alpha-GPC,
link |
we're taking those before or during an attempt to learn,
link |
These results point to the fact
link |
that it is after the learning and memory
link |
that you really want to get that big increase in epinephrine
link |
and the related molecules that will tamp down memory.
link |
So what this means is that if you are currently using
link |
caffeine or other compounds,
link |
and we'll talk about what those are and safety issues
link |
and so forth in a moment,
link |
if you're using those compounds
link |
in order to enhance learning and memory
link |
by taking them before or during a learning episode,
link |
well, then I encourage you to try and take them
link |
either late in the learning episode
link |
or immediately after the learning episode.
link |
Now, given everything I've told you up until now,
link |
why would I say late in the learning episode
link |
or immediately after?
link |
Well, when you ingest something by drinking it
link |
or you take it in capsule form,
link |
there's a period of time
link |
before that gets absorbed into the body
link |
and different substances such as caffeine,
link |
alpha-GPC, et cetera,
link |
are absorbed in from the gut and into the bloodstream
link |
and reach the brain and trigger these effects
link |
in the brain and body at different rates.
link |
So it's not instantaneous.
link |
Some have effects within minutes,
link |
others within tens of minutes and so on.
link |
It's really going to depend
link |
on the pharmacology of those things.
link |
And it's also going to depend
link |
on whether or not you have food in your gut,
link |
what else you happen to have circulating
link |
in your bloodstream, et cetera.
link |
But at a very basic level,
link |
we can confidently say that there are not one,
link |
not dozens, but as I mentioned before,
link |
hundreds of studies in animals and in humans
link |
that point to the fact that triggering the increase
link |
of adrenaline late in learning
link |
or immediately after learning
link |
is going to be most beneficial
link |
if your goal is to retain that information
link |
for some period of time
link |
and to reduce the number of repetitions required
link |
in order to learn that information.
link |
Now, I want to acknowledge that
link |
on previous episodes of this podcast
link |
and in appearing on other podcasts,
link |
I've talked a lot about things like non-sleep deep rest
link |
and naps and sleep as vital to the learning process.
link |
And I want to emphasize
link |
that none of that information has changed, right?
link |
I don't look at any of that information differently
link |
as the consequence of what I'm talking about today.
link |
It is still true that the strengthening
link |
of connections in the brain, the literal neuroplasticity,
link |
the changing of the circuits occurs
link |
during deep sleep and non-sleep deep rest.
link |
And it is also true, and I've mentioned these results
link |
earlier that two papers were published in Cell Reports,
link |
Cell Press Journal, Excellent Journal
link |
over the last few years,
link |
showing that brief naps of about 20 to up to 90 minutes
link |
in some period of time after an attempt to learn
link |
can enhance the rate of learning and memory.
link |
However, those bouts of sleep,
link |
the deep sleep that night, I should say,
link |
or those brief naps, or even the so-called NSDR
link |
as we call it, non-sleep deep rest
link |
that was used to enhance the learning and memory
link |
of particular pieces of information,
link |
either cognitive or physical information or both,
link |
that still can be performed,
link |
but it can be performed some hours later,
link |
even an hour later.
link |
It can be performed two hours later or four hours later.
link |
Remember, it's in these naps and in deep sleep
link |
that the actual reconfiguration of the neural circuits
link |
occurs, the strengthening of those neural circuits occurs.
link |
It is not the case that you need to finish a bout
link |
of learning and drop immediately into a nap or sleep.
link |
Some people might do that,
link |
but if you're really trying to optimize and enhance
link |
and improve your memory, the data from McGaugh and Cahill
link |
and many other laboratories that stemmed out
link |
from their initial work really point to the fact
link |
that the ideal protocol would be focus
link |
on the thing you're trying to learn very intensely.
link |
There are also some other things like error rates, et cetera.
link |
Please see our episodes on learning.
link |
We have a newsletter on how to learn better.
link |
You can access that at hubermanlab.com.
link |
It's a zero cost newsletter.
link |
You can grab that PDF, it lists out the things
link |
to do during the learning bout.
link |
Still try and get excellent sleep.
link |
Again, fundamentally important for mental health,
link |
physical health, and performance.
link |
And we can now extend from performance to saying,
link |
including learning and memory.
link |
Nap, if it doesn't interrupt your nighttime sleep,
link |
naps of anywhere from 10 to 90 minutes
link |
or non-sleep deep rest protocols
link |
will enhance learning and memory.
link |
But we can now add to that that spiking adrenaline,
link |
provided it can be done in a safe way,
link |
is going to reduce the number of repetitions required
link |
to learn and that should be done at the very tail end
link |
or immediately after a learning bout,
link |
which is compatible with all the other protocols
link |
And the reason I'm revisiting the stuff about sleep
link |
and non-sleep deep rest is I think that some people
link |
got the impression that they need to do that
link |
immediately after learning.
link |
And today I'm saying to the contrary,
link |
immediately after learning,
link |
you need to go into a heightened state of emotionality
link |
Now it's vitally important to point out
link |
that you do not need pharmacology.
link |
You don't need caffeine.
link |
You don't need alpha GPC.
link |
You don't need any pharmacologic substance
link |
to spike adrenaline,
link |
unless that's something that you already are doing
link |
or that you can do safely
link |
or that you know that you can do safely.
link |
And I always say, and I'll say it again,
link |
I'm not a physician, so I'm not prescribing anything.
link |
I'm a professor, so I profess things.
link |
You need to do what's safe for you.
link |
So if you're somebody who's not used to drinking caffeine
link |
and you suddenly drink four espresso
link |
after trying to learn something,
link |
you are going to have a severe increase in alertness
link |
and probably even anxiety.
link |
If you're panic attack prone,
link |
please don't start taking stimulants
link |
in order to learn things better.
link |
I don't just say that to protect me.
link |
I say that to protect you.
link |
And I should mention that if you're not accustomed
link |
to taking something,
link |
you always want to first check with your doctor, of course,
link |
but also move into that gradually, right?
link |
Start with the lowest effective dose,
link |
the minimal effective dose.
link |
And sometimes the minimal effective dose is zero milligrams.
link |
Why do I say that?
link |
Well, we already talked about results
link |
where they put people's arms into an ice bath
link |
in order to evoke adrenaline release.
link |
You are welcome to do that if you want.
link |
In fact, that's a pretty low cost, zero pharmacology,
link |
at least exogenous pharmacology way
link |
to approach this whole thing.
link |
That's a way of evoking your own natural epinephrine.
link |
And it turns out also dopamine release.
link |
You could take a cold shower, you could do an ice bath
link |
or get into a cold circulating bath.
link |
We've done several episodes on the utility of cold
link |
for health and performance.
link |
You can find those episodes at huberunelab.com.
link |
Also the episode with my colleague at Stanford
link |
from the biology department, Dr. Craig Heller.
link |
Lots of protocols in particular in the episode
link |
on cold for health and performance
link |
that describe how best to use the cold shower
link |
or the ice bath or the circulating cold bath
link |
in order to evoke epinephrine and dopamine release.
link |
The point is that the time in which you would want
link |
to do those protocols is after,
link |
ideally immediately after you're learning about,
link |
meaning when you're sitting down to learn new information
link |
or after trying to learn some new physical skill.
link |
Now, whether or not that's compatible
link |
with the other reasons you're doing
link |
cold, deliberate cold exposure,
link |
and whether or not that's compatible
link |
with the other things you're doing,
link |
that depends on the contour of your lifestyle,
link |
your training, your academic goals,
link |
your learning goals, et cetera.
link |
But if your specific purpose is to enhance learning
link |
and memory, you want to spike adrenaline afterwards.
link |
And so what I'm telling you is you can do that with caffeine.
link |
You can do that with alpha GPC.
link |
You can do that with a combination of caffeine and alpha GPC
link |
if you can do that safely.
link |
Some of you I know are using other forms of pharmacology.
link |
I did a long episode all about ADHD.
link |
I have to just really declare my stance very clearly
link |
that I am not a fan.
link |
I am actually opposed to people using prescription drugs
link |
who are not prescribed those drugs, right?
link |
In order to enhance alertness,
link |
I think there's a big addictive potential.
link |
There also is a potential to really disrupt
link |
one's own pharmacology around the dopaminergic system.
link |
However, some of you I know are prescribed things
link |
like Ritalin, Adderall, and Modafinil and things of that sort
link |
in order to increase alertness and focus.
link |
So for those of you that are prescribed those things
link |
from a board certified physician,
link |
you're going to have to decide
link |
if you're going to take them before trying to learn
link |
or after trying to learn.
link |
You also have to take into consideration
link |
that some of those drugs are very long acting,
link |
some are shorter acting and time that
link |
according to what you're trying to learn and when.
link |
So that's pharmacology.
link |
But as I've mentioned, there are the behavioral protocols.
link |
You can use cold and cold is an excellent stimulus
link |
because first of all, it doesn't involve pharmacology.
link |
Second of all, you can generally access it
link |
at low to zero cost, especially the cold shower approach.
link |
And third, you can titrate it.
link |
You can start with warmer water.
link |
You can make it very, very cold if that's your thing
link |
and you're able to tolerate that safely.
link |
You can make it moderately cold.
link |
How cold should it be in order to evoke adrenaline release?
link |
Well, it should be uncomfortably cold,
link |
but cold enough that you feel like you really want to get
link |
out, but can stay in safely.
link |
That's going to evoke adrenaline release.
link |
If it quickens your breathing, if it makes you go wide-eyed,
link |
that's increasing adrenaline release.
link |
In fact, those effects of going wide-eyed
link |
and quickening of the breathing and the challenges
link |
and thinking clearly, those are the direct effects
link |
of adrenaline on your brain and body.
link |
And of course, there are other ways to increase adrenaline.
link |
You could go out for a hard run.
link |
You could do any number of things
link |
that would increase adrenaline in your body.
link |
Which things you choose is up to you,
link |
but from a very clear, solid grounding in research data,
link |
we can confidently say that spiking adrenaline
link |
after interacting with some material,
link |
physical or cognitive material that you're trying to learn
link |
is going to be the best time to spike that adrenaline.
link |
Now, I realize that I'm being a bit redundant today,
link |
or perhaps a lot redundant in repeating over and over
link |
that the increase in epinephrine should occur
link |
either very late in an attempt to learn something
link |
or immediately after an attempt to learn something.
link |
I also want to emphasize the general contour
link |
of pharmacologic effects and of behavioral tools
link |
to create adrenaline.
link |
What do I mean by that sentence?
link |
What I mean is that McGaugh and colleagues
link |
explored a huge number of different compounds and approaches,
link |
everything from the hand into the ice bath
link |
to injecting adrenaline, to caffeine,
link |
to drugs that block the effects of adrenaline and caffeine,
link |
drugs like Musamol and Picrotoxin.
link |
Please don't take those.
link |
These are drugs that reduce or enhance
link |
the amount of adrenaline.
link |
And the overall takeaway is that anything
link |
that increases adrenaline will increase learning and memory
link |
and will reduce the number of repetitions required
link |
to learn something.
link |
Regardless of whether or not that something
link |
has an emotional intensity or not,
link |
provided that that spike in adrenaline occurs
link |
late in the learning or immediately after.
link |
And anything that reduces epinephrine and adrenaline
link |
will impair learning.
link |
And that's the key and novel piece of information
link |
that I'm adding now,
link |
which is if you're taking beta blockers, for instance,
link |
or if you're trying to learn something
link |
and it's not evoking much of an emotional response
link |
and you're not using any pharmacology or other methods
link |
to enhance adrenaline release after learning that thing,
link |
well, you're not going to learn it very well.
link |
In fact, McGaugh and Cahill did beautiful experiments
link |
in humans looking at how much adrenaline is increased
link |
by varying the emotional intensity of different things
link |
that they were trying to get people to learn,
link |
or by changing the dosage of epinephrine,
link |
or by changing the amount of epinephrine blocker
link |
that they injected, lots and lots of studies.
link |
The key thing to take away from those studies
link |
is that for some people,
link |
adrenaline was increased 600 to 700%.
link |
So six to seven fold over baseline
link |
in the amount of circulating epinephrine or adrenaline.
link |
And keep in mind, sometimes that increase
link |
was due to the actual thing they were trying to learn
link |
being very emotional, positive or negative emotion.
link |
And sometimes it was because they were using
link |
a pharmacologic approach or the ice bath approach.
link |
I don't think they ever used a cold shower approach,
link |
but that would have been a very effective one
link |
However, other people had a zero to 10% increase,
link |
so a very small increase in epinephrine.
link |
What we can confidently say on the basis of all those data
link |
is that the more epinephrine release,
link |
the better that people remembered the material.
link |
Over and over again, this was shown,
link |
whether or not it was for cognitive materials,
link |
so learning a language, learning a passage of words,
link |
learning mathematics,
link |
or whether or not it was for physical learning.
link |
I want to emphasize something about physical learning
link |
because I know a number of you are probably
link |
drinking a cup of coffee or having a cup of Yerba Mate
link |
or maybe even an energy drink
link |
and taking some Alpha GPC or something
link |
before physical exercise.
link |
I'm not saying that's a bad thing to do
link |
or that you wouldn't want to do that,
link |
but that's really to increase alertness.
link |
It won't enhance learning, at least not as well
link |
as doing those things after the physical exercise.
link |
Now, again, many of you, including myself,
link |
exercise for sake of the physical benefits of that exercise,
link |
the cardiovascular resistance training,
link |
but we're not really focused on learning and memory.
link |
So I emphasize this
link |
just so it's immensely clear to everybody.
link |
If you want to use those approaches
link |
of increasing adrenaline prior to
link |
or during physical training
link |
or cognitive work for that matter, be my guest.
link |
I think that's perfectly fine provided that's safe for you.
link |
It's only by moving it to late or after the learning
link |
that you're really shifting the role
link |
of that adrenaline increase to enhancing memory specifically.
link |
And as a cautionary note,
link |
don't think that you can push this entire system
link |
to the extreme over and over again,
link |
or chronically as we say, and get away with it.
link |
In other words, you're not going to be able to take
link |
a Alpha GPC and a double espresso,
link |
do your focus bout of work, cognitive or physical work,
link |
and then spike adrenaline again afterwards
link |
and remember that stuff even better, right?
link |
I'm not encouraging you.
link |
In fact, I'm discouraging you
link |
from chronically increasing adrenaline
link |
both during and after a given bout of work
link |
if the goal is to learn.
link |
Why do I say that?
link |
Well, work from McGaugh and Cahill and others has shown
link |
that it's not the absolute amount of adrenaline
link |
that you release in your brain and body
link |
that matters for enhancing memory.
link |
It's the amount of adrenaline that you release
link |
relative to the amount of adrenaline
link |
that was in your system just prior,
link |
in particular in the hour or two prior.
link |
So again, it's the Delta as we say, it's the difference.
link |
So if you're going to chronically increase adrenaline,
link |
you're not going to learn as well.
link |
The real key is to have adrenaline modestly low,
link |
perhaps even just as much as you need
link |
in order to be able to focus on something,
link |
pay attention to it, and then spike it afterwards.
link |
This is immensely important
link |
because while much of what we're talking about
link |
is actually a form of inducing
link |
a neurochemical acute stress,
link |
meaning a brief and rapid onset of stress,
link |
well, chronic stress, the chronic elevation
link |
of epinephrine and cortisol
link |
is actually detrimental to learning.
link |
And there's an entire category of literature,
link |
mainly from the work of the great
link |
and sadly the late Bruce McEwen
link |
from the Rockefeller University
link |
and some of his scientific offspring
link |
like the great Robert Sapolsky showing that chronic stress,
link |
chronic elevation of epinephrine
link |
actually inhibits learning and memory
link |
and also can inhibit immune system function,
link |
whereas acute, right?
link |
Sharp increases in adrenaline
link |
and cortisol actually can enhance learning
link |
and indeed can enhance the immune system.
link |
So if you really want to leverage this information,
link |
you might consider getting your brain and body
link |
into a very calm and yet alert state,
link |
so a high attentional state that will allow you
link |
to focus on what it is that you're trying to learn.
link |
We know focus is vital for encoding information
link |
and for triggering neuroplasticity,
link |
but remaining calm throughout that time
link |
and then afterwards spiking adrenaline
link |
and allowing adrenaline to have these incredible effects
link |
on reducing the number of repetitions required to learn.
link |
So if you're like me,
link |
you're learning about this information,
link |
this beautiful work of McGaugh and Cahill and others
link |
and thinking, wow, I should perhaps consider
link |
spiking my adrenaline in one form or another
link |
at the tail end or immediately follow
link |
and attempt to learn something.
link |
And yet we are not the first to have this conversation,
link |
nor were McGaugh and Cahill or any other researchers
link |
that I've discussed today,
link |
the first to start using this technique.
link |
In fact, there is a beautiful review
link |
that was published just this year, May of 2022
link |
in the journal Neuron, Cell Press Journal,
link |
excellent journal called Mechanisms of Memory Under Stress.
link |
And I just want to read to you the first opening paragraph
link |
of this review, which is, as the name suggests,
link |
all about memory and stress.
link |
So here I'm reading and I quote,
link |
"'In medieval times, communities threw young children
link |
in the river when they wanted them
link |
to remember important events.
link |
They believed that throwing a child in the water
link |
after witnessing historic proceedings
link |
would leave a lifelong memory for the events in the child.'"
link |
Believe it or not, this is true.
link |
This is a practice that somehow people arrived at.
link |
I don't know if they were aware of what adrenaline was,
link |
probably not, but somehow in medieval times,
link |
it was understood that spiking adrenaline
link |
or creating a robust emotional experience
link |
after an experience that one hoped a child would learn
link |
would encourage the child's nervous system,
link |
and they didn't even know what a nervous system was,
link |
but would encourage the brain and body of that child
link |
to remember those particular events.
link |
Very counterintuitive, if you ask me.
link |
I would have thought that the kid would remember
link |
only being thrown into the river.
link |
My guess is that they remembered that,
link |
but the idea here anyway is that they also remember
link |
the things that preceded being thrown into the river.
link |
So both interesting and amusing and somewhat,
link |
I should say, thought stimulating, really,
link |
that this is a practice that has been going on
link |
for many hundreds of years,
link |
and we are not the first to start thinking
link |
about using cold water as an adrenaline stimulus,
link |
nor are we the first to start thinking about using
link |
cold water-induced adrenaline
link |
as a way to enhance learning and memory.
link |
This has been happening since medieval times.
link |
So up until now, I've been talking about
link |
a pretty broad contour of these experiments.
link |
I've been talking about the underlying pharmacology,
link |
the role of epinephrine and so forth.
link |
I haven't really talked a lot
link |
about the underlying neural mechanisms,
link |
so I'm just going to take a minute or two
link |
and describe those for you because they are informative.
link |
We all have a brain structure called the amygdala.
link |
A lot of people think it's associated with fear,
link |
but it's actually associated with threat detection
link |
and more generally, and I should say more specifically,
link |
with detecting what sorts of events in the environment
link |
are novel and are linked to particular emotional states,
link |
both positive emotional states
link |
and negative emotional states.
link |
So the neurons in the amygdala are exquisitely good
link |
at figuring out, right, they don't have their own mind,
link |
but at detecting correlations between sensory events
link |
in the environment that trigger the release of adrenaline
link |
and what's going on in the brain.
link |
And because the amygdala is so extensively interconnected
link |
with other areas of the brain,
link |
it basically connects to everything
link |
and everything connects back to it,
link |
the amygdala is in a position
link |
to strengthen particular connections in the brain
link |
very easily, provided certain conditions are met,
link |
and those conditions are the ones
link |
we've been talking about up until now,
link |
emotional saliency that results in increases
link |
in epinephrine and cortisol
link |
or circulating epinephrine and cortisol
link |
being much higher than it was 10 minutes
link |
or 15 minutes before.
link |
And the net effect of the amygdala in this context
link |
is to take whatever patterns of neural activity
link |
preceded that increase in adrenaline and corticosterone
link |
and strengthen those synapses
link |
that were involved in that neural activity.
link |
So the amygdala doesn't have knowledge,
link |
it's not a thinking area, it's a correlation detector,
link |
and it's correlating neurochemical states
link |
of the brain and body with different patterns
link |
of electrical activity in the brain.
link |
This is important because it really emphasizes the fact
link |
that both negative and positive emotional states
link |
and the different but somewhat overlapping chemical states
link |
that they create are the conditions, as we say,
link |
the AND gates through which memory is laid down.
link |
AND gates will be familiar to those of you
link |
who have done a bit of computer programming.
link |
An AND gate is simply a condition
link |
in which you need one thing and another to happen
link |
in order for a third thing to happen.
link |
So you need epinephrine elevated
link |
and you need robust activity in a particular brain circuit
link |
if in fact that brain circuit is going to be strengthened.
link |
It's not sufficient to have one or the other,
link |
you need both, hence the name AND gate.
link |
And the amygdala is very good at establishing
link |
these AND gate contingencies.
link |
It's also a very generic brain structure
link |
in the sense that it doesn't really care
link |
what sorts of sensory events are involved
link |
provided they correlated in time
link |
with that increase in adrenaline and corticosterone.
link |
This has a wonderful side and a kind of dark side.
link |
The dark side is that PTSD and traumas of various kinds
link |
often involve a increase in adrenaline
link |
because whatever it was that caused the PTSD
link |
was indeed very stressful,
link |
caused these big increases in these chemicals.
link |
And because the amygdala is rather general
link |
in its functions, right?
link |
It's not tuned or designed in any kind of way
link |
to be specifically active in response
link |
to particular types of sensory events or perceptions.
link |
Well, then what it means is that we can start
link |
to become afraid of entire city blocks
link |
where one bad thing happened in a particular room
link |
of a particular building in a city block.
link |
We can become fearful of any place
link |
that contains a lot of people
link |
if something bad happened to us
link |
in a place that contained a lot of people.
link |
The amygdala is not so much of a splitter,
link |
as we say in science, we talk about lumpers and splitters.
link |
Lumpers are kind of generalizers, if that's even a word.
link |
And I think it is, someone will tell me
link |
one way or the other.
link |
And splitters are people that are ultra precise
link |
and specific and nuanced about every little detail.
link |
The amygdala is more of a lumper than a splitter
link |
when it comes to sensory events.
link |
Other areas of the brain only become active
link |
under very, very specific conditions
link |
and only those conditions.
link |
And similarly, epinephrine is just a molecule.
link |
It's just a chemical that's circulating
link |
in our brain and body.
link |
There's no epinephrine specifically for a cold shower
link |
that is distinct from the epinephrine
link |
associated with a bad event,
link |
which is distinct from the epinephrine
link |
associated with a really exciting event
link |
that makes you really alert.
link |
Epinephrine is just a molecule, it's generic.
link |
And so these systems have a lot of overlap
link |
and that can explain in large part
link |
why when good things happen in particular locations
link |
and in the company of particular people,
link |
we often generalize to large categories
link |
of people, places, and things.
link |
And when negative things happen in particular circumstances,
link |
we often generalize about people, places, and things
link |
associated with that negative event.
link |
So now I'd like to talk about other tools
link |
that you can leverage that have been shown
link |
in quality peer-reviewed studies
link |
to enhance learning and memory.
link |
And perhaps one of the most potent of those tools
link |
There are numerous studies on this in both animal models
link |
and fortunately now also in humans,
link |
thanks to the beautiful work of people like Wendy Suzuki
link |
from New York University.
link |
Wendy's lab has identified how exercise works
link |
to enhance learning and memory
link |
and other forms of cognition I should mention,
link |
as well as things that can augment,
link |
can enhance the effects of exercise
link |
on learning and memory and other forms of cognition.
link |
Wendy is going to be a guest on this podcast.
link |
It's actually the episode that follows this episode
link |
and includes a lot of material
link |
that we have not covered today.
link |
And she's an incredible scientist
link |
and has some incredible findings
link |
that I know everyone is going to find immensely useful.
link |
In the meantime, I want to talk about
link |
some of the general effects of exercise
link |
on learning and memory that she's discovered
link |
and that other laboratories have discovered.
link |
If you recall earlier,
link |
I mentioned that learning and memory
link |
almost always involves the strengthening
link |
of particular synapses and neural circuits in the brain
link |
and not so much the increase
link |
in the number of neurons in the brain.
link |
There is one exception, however,
link |
and we now have both animal data and some human data
link |
to support the fact that cardiovascular exercise
link |
seems to increase what we call dentate gyrus neurogenesis.
link |
Neurogenesis is the creation of new neurons.
link |
The dentate gyrus is a sub-region of the hippocampus
link |
that's involved in learning and memory of particular kinds,
link |
certain types of events, in particular contextual learning,
link |
but some other things as well,
link |
sometimes involved in spatial learning.
link |
There's a lot of debate
link |
about exactly what the dentate gyrus does,
link |
but for sake of this discussion,
link |
and I think everyone in the neuroscience community
link |
would agree that the dentate gyrus
link |
is important for memory formation and consolidation.
link |
The dentate gyrus does seem to be one region
link |
of the brain, certainly in the rodent brain,
link |
but more and more it's seeming also in the human brain
link |
where at least some new neurons
link |
are added throughout the lifespan.
link |
And as it turns out that cardiovascular exercise
link |
can increase the proliferation
link |
of new neurons in the structure
link |
and that those new neurons, excuse me,
link |
are important for the formation
link |
of certain types of new memories.
link |
There are wonderful data showing
link |
that if you use X irradiation,
link |
which is a way to eliminate the formation
link |
of those new cells or other tools and tricks
link |
to eliminate the formation of those cells,
link |
that you block the formation
link |
of certain kinds of learning and memory.
link |
What does this mean?
link |
Well, there are a lot of reasons
link |
for the statement I'm about to make
link |
that extend far beyond neurogenesis
link |
and the hippocampus learning and memory,
link |
but it's very clear that getting anywhere from 180,
link |
I should say a minimum of 180 to 200 minutes
link |
of so-called zone two cardiovascular exercise,
link |
so this is cardiovascular exercise
link |
that can be performed at a pretty steady state,
link |
which would allow you to just barely hold a conversation.
link |
So breathing hard, but not super hard.
link |
This isn't sprints or high intensity interval training,
link |
but doing that for 180 to 200 minutes per week total
link |
is it appears the minimum threshold
link |
for enhancing some of the longevity effects
link |
associated with improvements in cardiovascular fitness.
link |
And we believe that it is indirectly,
link |
I should say indirectly through enhancements
link |
in cardiovascular fitness that there are improvements
link |
in hippocampal dentate gyrus neurogenesis.
link |
What does that mean?
link |
The improvements in cardiovascular function
link |
are indirectly impacting the ability of the dentate gyrus
link |
to create these new neurons.
link |
To my knowledge, there's no direct relationship
link |
between exercise and stimulating
link |
the production of new neurons in the brain.
link |
It seems that it's the improvements in blood flow
link |
that also relate to improvements
link |
in things like glymphatic flow,
link |
the circulation of lymph fluid within the brain
link |
that are enhancing neurogenesis
link |
and that neurogenesis it appears is important.
link |
Now, in fairness to the landscape of neuroscience
link |
and my colleagues at Stanford and elsewhere,
link |
there is a lot of debate as to whether or not
link |
there is much, if any, neurogenesis
link |
in the adult human brain.
link |
But regardless, I think the data are quite clear
link |
that the 180 to 200 minutes minimum
link |
of cardiovascular exercise is going to be important
link |
for other health metrics.
link |
Now, it is clear that exercise can impact learning
link |
and memory through other non-neurogenesis,
link |
non new neuron type mechanisms.
link |
And one of the more exciting ones
link |
that has been studied over the years
link |
is this notion of hormones from bone
link |
traveling in the bloodstream to the brain
link |
and enhancing the function of the hippocampus.
link |
Now, the words hormones from bones is surprising to you.
link |
I'm here to tell you that yes, indeed,
link |
your bones make hormones.
link |
We call these endocrine effects.
link |
So in biology, we hear about autocrine,
link |
paracrine, and endocrine.
link |
And those different terms refer to over what distance
link |
a given chemical has an effect on a cell.
link |
For instance, a cell can have an effect on itself.
link |
It can have an effect on immediately neighboring cells,
link |
or it can have an effect on both itself,
link |
immediately neighboring cells,
link |
and cells far, far away in the body.
link |
And that last example of a given chemical
link |
or substance having an effect on the cell that produced it,
link |
plus neighboring cells, plus cells far away,
link |
is an endocrine effect.
link |
And a lot of hormones not all work in this fashion.
link |
Hence why we sometimes hear about endocrine and hormone
link |
is kind of synonymous terms.
link |
Your bones make chemicals that travel in the bloodstream
link |
and have these endocrine effects.
link |
So they're effectively acting as hormones.
link |
And one such chemical is something called osteocalcin.
link |
Now these findings arrive to us through various labs,
link |
but one of the more important labs
link |
for sake of this discussion today
link |
is the laboratory of Eric Kandel
link |
at Columbia Medical School.
link |
Eric is now, I believe in his mid to late 90s,
link |
still very sharp, and has studied learning and memory.
link |
It also turns out that he is an avid swimmer.
link |
Now I happen to know that Eric swims anywhere
link |
from a half a mile to a mile a day.
link |
And again, this is anecdotal.
link |
This is, I'm not referring to the published data just yet,
link |
but he credits that exercise as one of the ways
link |
in which he keeps his brain sharp
link |
and has indeed kept his brain sharp for many, many decades.
link |
And as I mentioned before, he's well into his 90s,
link |
so pretty impressive.
link |
His laboratory has studied the effects of exercise
link |
on hippocampal function and memory,
link |
and other laboratories have done that as well.
link |
And what they found is that cardiovascular exercise
link |
and perhaps other forms of exercise too,
link |
but mainly cardiovascular exercise,
link |
creates the release of osteocalcin from the bones
link |
that travels to the brain
link |
and to subregions of the hippocampus,
link |
and encourages the electrical activity
link |
and the formation and maintenance of connections
link |
within the hippocampus,
link |
and keeps the hippocampus functioning well
link |
in order to lay down new memories.
link |
Now, osteocalcin has a lot of effects
link |
besides just improving the function of the hippocampus.
link |
Osteocalcin is involved in bone growth itself.
link |
It's involved in hormone regulation.
link |
In fact, there's really nice evidence
link |
that it can regulate testosterone and estrogen production
link |
by the testes and ovaries,
link |
and a bunch of other effects in other organs of the body,
link |
because again, it's acting in this endocrine manner.
link |
It's arriving from bone
link |
to a lot of different organs to have effects.
link |
Load-bearing exercise in particular
link |
turns out to be important
link |
for inducing the release of osteocalcin.
link |
And when you think about this, it makes sense.
link |
A nervous system exists for a lot of reasons,
link |
to sense, perceive, et cetera.
link |
You've got taste, you've got smell, you've got hearing.
link |
But the vast majority of brain real estate,
link |
especially in humans, is dedicated to two things.
link |
We have an enormous amount of brain real estate
link |
devoted to vision, certainly compared to other senses,
link |
the ability to generate coarse movements of the body,
link |
the ability, excuse me, to generate fine movements
link |
of the body, like the digits, or to wink one eye,
link |
or to tilt your head in a particular way,
link |
or move your lips, or move your face,
link |
and do all sorts of different things
link |
in a very nuanced and detailed way.
link |
So much of our brain real estate is devoted to movement,
link |
that it's been hypothesized for more than a half century,
link |
but especially in recent years,
link |
as we've learned more about the function of the brain
link |
at a really detailed circuit level,
link |
that the relationship between the brain and body
link |
and the maintenance,
link |
and perhaps even the improvement of neural circuitry
link |
in the brain, depends on our body movements
link |
and the signal from the body that our brain is still moving.
link |
So think about that.
link |
How would your brain know if your body was moving regularly
link |
and how would it know how much it was moving?
link |
How would it know which limbs it was moving?
link |
Well, you could say, if the heart rate is increased,
link |
then the blood flow will be increased,
link |
and then the brain will know.
link |
Ah, but how does your brain know
link |
that it's increased blood flow due to movement
link |
and not to, for instance, just stress, right?
link |
Maybe you actually can't move
link |
and you're very stressed about that,
link |
and so the increased blood flow
link |
is simply a consequence of increased stress.
link |
The fact that osteocalcin is released from bone,
link |
and in particular can be released
link |
in response to load-bearing exercise,
link |
so this would be running.
link |
Again, weightlifting hasn't been tested directly,
link |
but one would imagine anything that involves jumping
link |
and landing or weightlifting or body weight movements
link |
and things of that sort.
link |
That's a signal to release osteocalcin,
link |
and we know that signal occurs,
link |
that is directly reflective of the fact
link |
that the body was moving and moving in particular ways.
link |
In fact, you could imagine that big bones,
link |
like your femur, are going to release more osteocalcin
link |
or be in a position to release more osteocalcin
link |
than fine movements, like the movements of the digits.
link |
And this idea that the body is constantly signaling
link |
to the brain about the status of the body
link |
and the varying needs of the brain
link |
to update its brain circuitry is a really attractive idea
link |
that fits entirely with the biology of exercise,
link |
osteocalcin, and hippocampal function.
link |
I do want to mention that I'm not the first
link |
to raise this hypothesis.
link |
This hypothesis actually was discussed
link |
in a fair amount of detail by John Rady,
link |
who's a professor in Harvard Medical School.
link |
He wrote a book called Spark,
link |
which was one of the early books,
link |
at least from an academic, about brain plasticity
link |
and the relationship between exercise
link |
and movement in plasticity.
link |
And John, who I have the good fortune to know,
link |
has described to me experiments,
link |
or I should say observations,
link |
of species of ocean-dwelling animals that have,
link |
at least for the early part of their life,
link |
a very robust and complicated nervous system.
link |
But then these particular animals are in the habit
link |
of plopping down onto a rock.
link |
They find a kind of a safe, comfy space,
link |
and they actually stick to that rock,
link |
and they don't move anymore for a certain portion,
link |
I should say the late portion of their life.
link |
And it is at the transition between moving a lot
link |
and being stationary that those animals
link |
actually digest their own brain.
link |
They literally metabolize a good portion
link |
of their nervous system because they decide,
link |
well, don't need this anymore, and gobble it up,
link |
use it for its nutritional value,
link |
and then sit there like a moron version of themselves
link |
with a limited amount of brain tissue
link |
because they don't need to move anymore.
link |
Now, I certainly don't want to give the message
link |
that just moving, just exercise,
link |
is sufficient to keep the neural architecture
link |
of your brain healthy, young, and able to learn.
link |
While that might be true,
link |
it's also important to actually engage in attempts
link |
to learn new material, either physical material,
link |
so new types of movements and skills,
link |
and or new types of cognitive information,
link |
languages, mathematics, history, current events,
link |
all sorts of things that involve your brain.
link |
Nonetheless, it's clear that physical movement
link |
and cognitive ability and the potential
link |
to enhance cognitive ability
link |
and the ability to learn new physical skills
link |
are intimately connected.
link |
And osteocalcin appears to be at least one way
link |
in which that brain-body relationship
link |
is established and maintained.
link |
So given the information about osteocalcin and movement,
link |
and given the information about spiking adrenaline late
link |
or after a period of attempt to learn,
link |
you might be asking, when is the best time to exercise?
link |
Now, unfortunately, that has not been addressed
link |
in a lot of varying detail
link |
where every sort of variation on the theme
link |
has been carried out.
link |
And yet, Wendy Suzuki's lab
link |
has done really beautiful experiments
link |
where they have people exercise,
link |
generally it was in the morning,
link |
but at other periods of the day as well.
link |
And what they find is that at least as late
link |
as two hours after that exercise,
link |
there's an enhancement in learning and memory.
link |
Now, I want to be clear,
link |
we don't know whether or not that exercise
link |
led to big increases in adrenaline.
link |
It may be that those forms of exercise were modest enough
link |
or didn't challenge people enough
link |
that they merely got a lot of blood flow going
link |
and that the improvements in learning and memory
link |
were related to blood flow,
link |
and we presume increases in osteocalcin.
link |
However, you could imagine
link |
a couple of different logical protocols
link |
based on what we've talked about.
link |
Let's say you were going to do a form of exercise
link |
that was going to spike adrenaline a lot.
link |
So this would be exercise
link |
that really challenges your system
link |
and forces you to kind of push through a burn, right?
link |
So here I'm mainly thinking about cardiovascular exercise,
link |
but it could even be yoga,
link |
it could be resistance training.
link |
If it's going to give you a big spike in adrenaline,
link |
it's going to take some serious effort,
link |
then logically speaking,
link |
you would want to place that after a learning bout
link |
in order to increase learning and memory.
link |
However, if you're using the exercise
link |
in order to enhance blood flow
link |
and to enhance osteocalcin release
link |
in efforts to augment the function of your hippocampus,
link |
I think it stands to reason that doing that exercise
link |
sometime within the hour to three hours
link |
preceding an attempt to learn makes a lot of sense.
link |
And there I'm basing it on the human data
link |
from Wendy Suzuki's lab,
link |
I'm basing it on the studies from Eric Kandel
link |
and from others labs.
link |
Again, right now there hasn't been an evaluation
link |
of a lot of different protocols to arrive
link |
at the peer reviewed laboratory super protocol.
link |
However, since what we're talking about
link |
is using activities like exercise
link |
that most of us probably, perhaps all of us
link |
should be doing regularly anyway.
link |
And I do believe most, if not all of us
link |
should probably regularly be trying to learn
link |
and keep our brain functioning well
link |
and acquire new knowledge
link |
because it's just a wonderful part of life.
link |
And there is evidence that that actually
link |
can keep your brain young, so to speak.
link |
Well then, exercising either before or after
link |
a learning bout makes a lot of sense
link |
with the emphasis on after a learning bout
link |
if the form of exercise spikes a lot of adrenaline
link |
for all the reasons we talked about before.
link |
Okay, so we've talked about two major categories
link |
of protocols to improve memory that are grounded
link |
in quality peer reviewed science.
link |
And there is yet another third protocol
link |
that we'll talk about in a few minutes.
link |
But before we do that,
link |
I want to briefly touch on an aspect of memory.
link |
In fact, two aspects of memory
link |
that I get a lot of questions about.
link |
The first one is photographic memory.
link |
To be clear, there are people out there
link |
who have a true photographic memory.
link |
They can look at a page of text,
link |
they can scan it with their eyes,
link |
and they can essentially commit that to memory
link |
with very little, if any effort.
link |
While it might seem that having a photographic memory
link |
is a very attractive skill to have,
link |
I should caution you against believing that
link |
because it turns out that people
link |
with true photographic memory
link |
are often very challenged at remembering
link |
things that they hear,
link |
and oftentimes are not so good at learning physical skills.
link |
It's not always the case, but often that's the case.
link |
So be careful what you wish for.
link |
If you do have a photographic memory,
link |
there are certain professions
link |
that lend themselves particularly well to you.
link |
And indeed, a lot of people with photographic memory
link |
have to find a profession and have to move through life
link |
in a way that is in concert with that photographic memory.
link |
So again, it's a super ability,
link |
it's a hyper ability,
link |
and yet it's not necessarily one
link |
that is desirable for most people.
link |
There's also this category
link |
of what are called super recognizers.
link |
These people are, I should mention,
link |
highly employable by government agencies.
link |
These are people that have an absolutely astonishing ability
link |
to recognize faces and to match faces to templates.
link |
They can look at a photograph of, say,
link |
somebody on a most wanted list,
link |
and then they can look at video footage
link |
of, let's say, an airport or a mall or a city street
link |
at fairly low resolution,
link |
and they can spot the person whose face matches
link |
that photograph that they looked at.
link |
Even if that video or other footage is of people's profiles
link |
or even the tops of their heads
link |
and just a portion of their forehead,
link |
these people have just an incredible ability
link |
to recognize faces and to template match.
link |
And again, these people often will take jobs with agencies
link |
where this sort of thing is important.
link |
Some of you out there probably are super recognizers
link |
and may or may not notice it.
link |
If you've ever had the experience of watching a movie
link |
and thought to yourself,
link |
wow, her mouth looks so much like my cousin's mouth,
link |
or you look at a character in a movie or television show
link |
and you think, wow, they look almost like
link |
the younger sister of so-and-so,
link |
well, then it's very likely that you have this,
link |
or at least a mild form of this super recognizer ability.
link |
That is not memory per se.
link |
That is the hyperfunctioning of an area of the brain
link |
that we call the fusiform gyrus.
link |
The fusiform gyrus is literally a face recognition area
link |
and a face template matching area,
link |
and it harbors neurons that respond to faces generally.
link |
So as humans and other non-human primates
link |
care a lot about faces and their emotional content,
link |
and the identity of faces is super important to us
link |
for all the kinds of reasons that are probably obvious,
link |
knowing who's friend, who's foe, who do you know well,
link |
who's famous, who's not famous, et cetera.
link |
That is not memory per se.
link |
And yet, if you're a super recognizer,
link |
or I guess we could call it a moderate face recognizer,
link |
or not very good at recognizing faces,
link |
because indeed there are some people
link |
that are kind of face blind,
link |
they don't actually recognize people.
link |
When they walk in the room,
link |
I used to work with somebody like this,
link |
I'd walk into his office and he'd say,
link |
are you rich or are you Andrew?
link |
I'd say, well, am I rich rich, like, you know, wealth rich?
link |
And he'd say, no, are you Richard or are you Andrew?
link |
And I'd say, I'm Andrew, we know each other really well.
link |
He said, oh, I'm sorry, I'm kind of face blind.
link |
And it actually tend to be better or worse
link |
depending on how much he was working.
link |
Ironically, the more rested he was,
link |
the more face blind he would become.
link |
So it wasn't a sleep deprivation thing.
link |
That exists, that's out there.
link |
There's the full constellation
link |
of people's ability to recognize faces.
link |
That's not really memory.
link |
And yet visual function is a profoundly powerful way
link |
in which we can enhance our memory.
link |
So whether or not you're a super recognizer of faces,
link |
whether or not you are face blind or anything in between.
link |
Next, I'm going to tell you about a study
link |
which points out the immense value of visual images
link |
for laying down memories.
link |
And you can leverage this information.
link |
And this involves both the taking a photograph,
link |
something that's actually quite easy,
link |
easily done these days with your phone,
link |
as well as your ability to take mental photographs
link |
by literally snapping your eyelid shut.
link |
So I just briefly want to describe this paper
link |
because it provides a tool that you can leverage
link |
in your attempt to learn and remember things better.
link |
The title of this paper is Photographic Memory,
link |
the effects of our volitional photo taking
link |
on memory for visual and auditory aspects of an experience.
link |
I really liked this paper
link |
because it refers to photographic memory,
link |
not in the context of photographic memory
link |
that we normally hear about
link |
where people are truly photographic,
link |
look at a page and somehow absorb all that information
link |
and commit it to memory,
link |
but rather the use of camera photographs
link |
or the use of mental camera photographs,
link |
literally looking at something and deciding blink
link |
and snapping a, so to speak,
link |
snapping a snapshot of whatever it is
link |
that you were looking at and remembering the content.
link |
The reason I like this paper
link |
and the reason I'm attracted to this issue
link |
of mental snapshots is this is something
link |
that I've been doing since I was a kid.
link |
I don't know why I started doing it,
link |
but every once in a while, I would say maybe twice a year,
link |
I would look at something
link |
and decide to just snap a mental snapshot of it.
link |
And I've maintained very clear memories
link |
of those visual scenes.
link |
Two years ago, I was in an Uber and I looked out the window
link |
and it was a street scene.
link |
I was actually in New York at the time.
link |
And I decided for reasons that are still unclear to me
link |
to take a mental snapshot of this city street image,
link |
even though nothing interesting in particular was happening.
link |
And I do recall that there was a guy wearing a yellow shirt,
link |
walking, there was some construction, et cetera.
link |
I can still see that image in my mind's eye
link |
because I took this mental snapshot.
link |
This paper addresses whether or not
link |
this mental snapshotting thing is real.
link |
And this is something that I think a lot of people
link |
will resonate with, whether or not the constant taking
link |
of pictures on our phones or with other devices
link |
is either improving or degrading our memory.
link |
You can imagine an argument for both.
link |
A lot of people are taking pictures
link |
that they never look at again.
link |
And so in a sense, they're outsourcing their visual memory
link |
of events into their phone or to some other device.
link |
And they're not ever accessing the actual image again.
link |
They're not looking at it, right?
link |
You're not printing out those photos.
link |
You're not scanning through your phone again.
link |
Sometimes you might do that, but most of the time,
link |
Most of the photographs that people take in,
link |
they're not revisiting again.
link |
So the motivation for this study was that
link |
previous experiments had shown that
link |
if people take photos of a scene or a person or an object,
link |
that they are actually less good at remembering
link |
the details of that scene or object, et cetera.
link |
This study challenged that idea and raised the hypothesis
link |
that if people are allowed to choose
link |
what they take photos of, that taking photos,
link |
again, this is with a camera, not mental snapshotting,
link |
that taking those photos would actually enhance their memory
link |
for those objects, those places, those people,
link |
and in fact, details of those object places and people.
link |
And indeed, that's what they found.
link |
So in contrast to previous studies,
link |
where people had been more or less told,
link |
take photos of these following objects
link |
or these following people or these following places,
link |
and then they were given a memory test at some point later,
link |
in this study, people were given volitional control, right?
link |
They were given agency in making the decision
link |
of what to take photos of.
link |
And I'll just summarize the results.
link |
We'll provide a link to this study.
link |
I should say that some of the stuff that they tested
link |
was actually pretty challenging.
link |
Some of them were pottery and other forms of ceramics
link |
that are of the sort that you see
link |
if you go to a big museum in a big city,
link |
and if you've ever done that
link |
and you see all the different objects,
link |
there are a lot of details in those objects,
link |
and a lot of those objects look a lot alike.
link |
And so, you know, some will have two handles,
link |
some will have one handle, the position of the handles,
link |
how broad or narrow these things are.
link |
You know, a lot of this is pretty detailed stuff.
link |
They also took photos of other things.
link |
So basically what they found was that
link |
if people take pictures of things
link |
and they choose which things they are taking pictures of,
link |
right, it's up to them, it's volitional,
link |
that there's enhanced memory for those objects later on.
link |
However, it degraded their ability
link |
to remember auditory information.
link |
So what this means is that
link |
when we take a picture of something or a person,
link |
we are stamping down a visual memory of that thing,
link |
and that makes sense, it's a photograph after all,
link |
but we are actually inhibiting our ability
link |
to remember the auditory, the sound components
link |
of that visual scene or what the person was saying.
link |
Very interesting, and points to the fact
link |
that the visual system can out-compete the auditory system,
link |
at least in terms of how the hippocampus
link |
is encoding this information.
link |
The other finding I find particularly interesting
link |
within this study is that it didn't matter
link |
whether or not they ever looked at the photos again.
link |
So they actually had people take photos
link |
or not take photos of different objects.
link |
They had some people keep their photos
link |
and they had other people delete their photos,
link |
and turns out that whether or not people kept the photos
link |
or deleted those photos had no bearing
link |
on whether or not they were better or worse
link |
at remembering things, they were always better
link |
at remembering them as compared to not taking photos of them.
link |
What does this mean?
link |
It means if you really want to remember something
link |
or somebody, take a photo of that thing or person,
link |
pay attention while you take the photo,
link |
but it doesn't really matter if you look at the photo again.
link |
Somehow the process of taking that photo,
link |
probably looking at it, you know,
link |
in a camera typically we'd say through the viewfinder
link |
or now because of digital cameras on the screen
link |
on the back of that camera or on your phone,
link |
that framing up of the photograph
link |
stamps down a visual image in your mind
link |
that is more robust at serving a memory
link |
than had you just looked at that thing with your own eyes.
link |
Very interesting and raises all sorts of questions for me
link |
about whether or not it's because you're framing up
link |
a small aperture or a small portion of the visual scene.
link |
That's one logical interpretation,
link |
although they didn't test that.
link |
I should also say that they found that whether or not
link |
you looked at a photo that you took
link |
or whether or not you deleted it
link |
and never looked at it again,
link |
didn't just enhance visual memory
link |
or the memory for the visual components of that image,
link |
but it always reduced your ability to remember
link |
sounds associated with that experience.
link |
So that's interesting.
link |
And then last but not least,
link |
and perhaps most interesting, at least to me,
link |
was the fact that you didn't even need a camera
link |
to see this effect.
link |
If subjects looked at something
link |
and took a mental photograph of that thing,
link |
it enhanced their visual memory of that thing
link |
significantly more than had they not taken a mental picture.
link |
In fact, it increased their memory of that thing
link |
almost as much as taking an actual photograph
link |
with an actual camera.
link |
And the reason I find this so interesting
link |
is that a lot of what we try and learn is visual.
link |
And for a lot of people,
link |
the ability to learn visual information feels challenging
link |
and we'll look at something
link |
and we'll try and create some detailed understanding of it.
link |
We'll try and understand the relationships
link |
between things in that scene.
link |
It does appear based on the study
link |
that the mere decision to take a mental snapshot,
link |
like, okay, I'm going to blink my eyelids
link |
and I'm going to take a snapshot of whatever it is I see
link |
can actually stamp down a visual memory
link |
much in the same way that a camera can stamp down
link |
a visual memory, of course,
link |
through vastly distinct mechanisms.
link |
No discussion of memory would be complete
link |
without a discussion of the ever intriguing phenomenon
link |
This sense that we've experienced something before,
link |
but we can't quite put our finger on it.
link |
Where and when did it happen?
link |
Or the sense that we've been someplace before
link |
or that we are in a familiar state or place
link |
or context of some kind.
link |
Now, I've talked about this on the podcast before,
link |
at least I think I have,
link |
and the way this works has been defined
link |
largely by the wonderful work of Susumu Tonogawa
link |
at Massachusetts Institute of Technology, MIT.
link |
Susumu collected a Nobel Prize quite appropriately
link |
for his beautiful work on immunology,
link |
and he's also a highly accomplished neuroscientist
link |
who studies memory and learning and deja vu.
link |
And I should also mention the beautiful work of Mark Mayford
link |
at the Scripps Institute in UC San Diego,
link |
beautiful work on this notion of deja vu.
link |
Here's what they discovered.
link |
They evaluated the patterns of neural firing
link |
in the hippocampus as subjects learn new things, okay?
link |
So neuron A fires, then neuron B fires,
link |
then neuron C fires in a particular sequence.
link |
Again, the firing of neurons in a particular sequence,
link |
like the playing of keys on a piano in a particular sequence
link |
leads to a particular song on the piano
link |
and leads to a particular memory
link |
of an experience within the brain.
link |
They then used some molecular tools and tricks
link |
to label and capture those neurons
link |
such that they could go back later
link |
and activate those neurons in either the same sequence
link |
or in a different sequence to the one that occurred
link |
during the formation of the memory.
link |
And to make a long story short,
link |
and to summarize multiple papers
link |
published in incredibly high tier journals,
link |
journals like Nature and Science,
link |
which are extremely stringent,
link |
found that whether or not those particular neurons
link |
were played in the precise sequence
link |
that happened when they encoded the memory,
link |
or whether or not those neurons were played
link |
in a different sequence,
link |
or even if those neurons were played,
link |
activated that is, all at once with no temporal sequence,
link |
all firing in concert, all at once,
link |
evoked the same behavior,
link |
and in some sense, the same memory.
link |
So at a neural circuit level, this is deja vu.
link |
This is a different pattern of firing
link |
of neurons in the brain,
link |
leading to the same sense of what happened,
link |
leading to a particular emotional state or behavior.
link |
Now, whether or not the same sort of phenomenon occurs
link |
when you're walking down the street
link |
and suddenly you feel as if,
link |
wow, I feel like I've been here before.
link |
You meet someone and you feel like,
link |
gosh, I feel like I know you.
link |
I feel like there's some familiarity here
link |
that I can't quite put my finger on.
link |
We don't know for sure that that's what's happening,
link |
but this is the most mechanistic and logical explanation
link |
for what has for many decades, if not hundreds of years,
link |
has been described as deja vu.
link |
So for those of you that experienced deja vu often,
link |
just know that this reflects a normal pattern
link |
of encoding experiences and events within your hippocampus.
link |
I'm not aware of any pathological situations
link |
where the presence of deja vu inhibits daily life.
link |
Some people like the sensation of deja vu.
link |
Other people don't.
link |
Almost everybody, however, describes it as somewhat eerie,
link |
this idea that even though you're in a very different place,
link |
even though you're interacting with a very different person,
link |
that you could somehow feel as if this has happened before.
link |
And just realize this, that your hippocampus,
link |
while it is exquisitely good at encoding
link |
new types of perceptions, new experiences, new emotions,
link |
new contingencies and relationships of life events,
link |
it is not infinitely large,
link |
nor does it have an infinite bucket full of different
link |
options of different sequences for those neurons to play.
link |
So in a lot of ways, it makes perfect sense
link |
that sometimes we would feel as if a given experience
link |
had happened previously.
link |
I'd like to cover one additional tool that you can use
link |
to improve learning and memory.
link |
And I should mention, this is a particularly powerful one,
link |
and it's one that I'm definitely going to employ myself.
link |
This is based on a paper from none other
link |
than Wendy Suzuki at New York University.
link |
We talked about her a little bit earlier.
link |
And again, she's going to be on the podcast
link |
in our next episode, and is just an incredible researcher.
link |
I've known Wendy for a number of years,
link |
and it's only in the last, I would say five or six years,
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that she's really shifted her laboratory
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toward generating protocols that human beings can use.
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And she's putting that to great effect,
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great positive effect, I should say,
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publishing papers of the sort that I'm about to describe,
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but also incorporating some of these tools and protocols
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into the learning curriculum and the lifestyle curriculum
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of students at NYU, which I think is a terrific initiative.
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So you don't need to be an NYU student
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in order to benefit from her work.
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I'm going to tell you about some of that work now,
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and she'll tell you about this and much more
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in the episode that follows this one.
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The title of this paper will tell you a lot
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about where we're going.
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The title is, Brief Daily Meditation Enhances Attention,
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Memory, Mood, and Emotional Regulation
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in Non-Experienced Meditators.
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If ever there was an incentive to meditate,
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it is the data contained within this paper.
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I want to briefly describe the study.
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And then I also want to emphasize
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that when you meditate is absolutely critical.
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I'll talk about that just at the end.
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This is a study that involves subjects aged 18 to 45,
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none of whom were experienced meditators
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prior to this study.
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There were two general groups in this study.
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One group did a 13 minute long meditation.
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And this meditation was a fairly conventional meditation.
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They would sit or lie down.
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They would do somewhat of a body scan evaluating,
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for instance, how tense or relaxed they felt
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throughout their body and they would focus on their breathing
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trying to bring their attention back to their breathing
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and to the state of their body as the meditation progressed.
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The other group, which we can call the control group,
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listened to, of all things, a podcast.
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They did not listen to this podcast.
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They listened to Radiolab, which is a popular podcast
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for an equivalent amount of time,
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but they were not instructed to do any kind of body scan
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or pay attention to their breathing.
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Every subject in the study either meditated daily
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or listened to a equivalent duration podcast daily
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for a period of eight weeks.
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And the experimenters measured a large number of things,
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of variables, as we say.
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They looked at measures of emotion regulation.
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They actually measured cortisol, a stress hormone.
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They measured, as the title suggests,
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attention and memory and so forth.
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And the basic takeaway of this study is that eight weeks,
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but not four weeks of this daily 13 minute a day meditation
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had a significant effect in improving attention, memory,
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mood, and emotion regulation.
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I find this study to be very interesting
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and in fact important because most of us have heard
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about the positive effects of meditation
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on things like stress reduction
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or on things such as improving sleep.
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And I want to come back to sleep in a few moments
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because it turns out to be very important feature
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This particular study I like so much
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because they used a really broad array of measurements
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for cognitive function,
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things like the Wisconsin card sorting task.
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I'm not going to go into this, things like the Stroop task.
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And they also, as I mentioned, measured cortisol
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and many other things, including not surprisingly memory
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and people's ability to remember
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certain types of information.
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In fact, varied types of information.
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And the basic takeaway was, again,
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that you could get really robust improvements
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in learning and memory, mood, and attention
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from just 13 minutes a day of meditation.
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Now there's an important twist in this study
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that I want to emphasize.
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If you read into the discussion of this study,
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it's mentioned that somehow meditation did not improve,
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but actually impaired sleep quality
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compared to the control subjects.
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You might think, wow, why would that be?
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I mean, meditation is supposed to reduce our stress,
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stress is supposed to inhibit sleep,
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and therefore why would sleep get worse?
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Well, what's interesting is the time of day
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when most of these subjects tended to do their meditation.
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Most of the subjects in this study
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did their meditation late in the day.
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This is often the case in experiments.
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I know this because we run experiments
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with human subjects in my laboratory
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and people are paid some amount of money
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in order to participate,
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or they're given something as compensation
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for being in the study,
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but oftentimes the meditation, or in the case of my lab,
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the respiration work or other kinds of things
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that they're assigned to do are not their top, top priority,
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and we understand this.
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But in this study, the majority of subjects here I'm reading
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completed their meditation sessions
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from somewhere between 8 and 11 p.m.,
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and sometimes even between 12 and 3 a.m.
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I think there probably were a lot of college students
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enrolled in this study,
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and their hours often are late shifted.
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That impaired sleep, and this raises a bigger theme
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that I think is important.
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Many times before on this podcast,
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and certainly in the episode on Mastering Sleep
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and Conquering or Mastering Stress,
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those episodes, we talked about the value again
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of these non-sleep deep rest protocols, NSDR,
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for reducing the activity of your sympathetic nervous system
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the alertness, so-called stress arm
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of your autonomic nervous system,
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that makes you feel really alert.
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NSDR is superb for reducing your level of alertness,
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increasing your level of calmness,
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and putting you into a so-called
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more parasympathetic relaxed state.
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Meditation does that too, but it also increases attention.
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If you think about meditation,
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meditation involves focusing on your breath
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and constantly focusing back on your breath
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and trying to avoid the distraction of things
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you're thinking or things that you're hearing
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and coming so-called back to your body, back to your breath.
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So meditation is actually has a high attentional load.
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It requires a lot of prefrontal cortical activity
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that's involved in attention,
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which then logically relates
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to one of the outcomes of this study,
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which is that attention abilities improved
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in daily meditators.
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It also points out that increasing the level of attention
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and the activity of your prefrontal cortex may,
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and I want to emphasize may
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because I'm here I'm speculating
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about the underlying mechanism,
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inhibit your ability to fall asleep.
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So while we have meditation on the one hand
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that does tend to put us into a calm state,
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but it is a calm, very focused state.
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In fact, attention and focus are inherent
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to most forms of meditation.
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Non-sleep deep rest, such as yoga nidra,
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as some of you know it to be, or NSDR.
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There's a terrific NSDR script that's available free online
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that's put out by Made For,
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so you can go to YouTube, NSDR Made For.
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You can also just do a search for NSDR.
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There are a number of these available out there,
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again, at no cost.
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Those NSDR protocols tend to put people
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into a state of deep relaxation,
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but also very low attention.
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And we have to assume very low activation
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of the prefrontal cortex.
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So the takeaways from the study are several fold.
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First of all, that daily meditation of 13 minutes
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can enhance your ability to pay attention and to learn.
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It can truly enhance memory.
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However, you need to do that for at least eight weeks
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in order to start to see the effects to occur.
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And we have to presume that you have to continue
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those meditation training sessions.
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In fact, they found that if people
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only did four weeks of meditation,
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these effects didn't show up.
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Now, eight weeks might seem like a long time,
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but I think that 13 minutes a day
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is not actually that big of a time commitment.
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And the results of this study certainly incentivize me
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to start adopting a, I'm going for 15 minutes a day now.
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I've been an on and off meditator for a number of years.
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I've been pretty good about it lately,
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but I confess I've been doing far shorter meditations
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of anywhere from three to five or maybe 10 minutes.
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I'm going to ramp that up to 15 minutes a day.
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And I'm doing that specifically to try
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and access these improvements in cognitive ability
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and our abilities to learn.
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Also based on the data in this paper,
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I'm going to do those meditation sessions
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either early in the day,
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such as immediately after waking or close to it.
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So I might get my sunshine first.
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very big on getting sunlight in the eyes early in the day,
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as much as one can and as early as one can
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once the sun is out,
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but certainly doing it early in the day
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and not past 5 PM or so in order to make sure
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that I don't inhibit sleep.
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Because I think this result that they describe
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of meditation inhibiting quality sleep
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compared to controls is an important one
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to pay attention to, no pun intended.
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Today, we covered a lot of aspects of memory
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and how to improve your memory.
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We talked about the different forms of memory
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and we talked about some of the underlying neural circuitry
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of memory formation.
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And we talked about how the emotional saliency
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and intensity of what you're trying to learn
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has a profound impact on whether or not you learn
link |
in response to some sort of experience,
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whether or not that experience is reading
link |
or mathematics or music or language or a physical skill,
link |
The more intense of an emotional state that you're in
link |
in the period immediately following that learning,
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the more likely you are to remember
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whatever it is that you're trying to learn.
link |
And we talked about the neurochemicals
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that explain that effect,
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about epinephrine and corticosterones like cortisol
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and how adjusting the timing of those
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is so key to enhancing your memory.
link |
And we talked about the different ways
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to enhance those chemicals,
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everything ranging from cold water to pharmacology
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and even just adjusting the emotional state within your mind
link |
in order to stamp down and remember experiences better.
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We also talked about how to leverage exercise
link |
in particular load-bearing exercise
link |
in order to evoke the release of hormones like osteocalcin,
link |
which can travel from your bones to your brain
link |
and enhance your ability to learn.
link |
And we talked about a new form of photographic memory,
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not the traditional type of photographic memory
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in which people can remember everything
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they look at very easily,
link |
but rather taking mental snapshots of things that you see.
link |
Again, emphasizing that that will create a better memory
link |
of what you see when you take that mental snapshot,
link |
but will actually reduce your memory
link |
for the things that you hear at that moment.
link |
And we discussed the really exciting data
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looking at how particular meditation protocols
link |
can enhance memory, but also attention and mood.
link |
However, if done too late in the day,
link |
can actually disrupt sleep precisely
link |
because those meditation protocols can enhance attention.
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Now, I know that many of you are interested
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in neurochemicals that can enhance learning and memory,
link |
and I intend to cover those in deep detail
link |
in a future episode.
link |
However, for sake of what was discussed today,
link |
please understand that any number
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of different neurochemicals can evoke
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or can increase the amount of adrenaline
link |
that's circulating in your brain and body.
link |
And it's less important how one accesses
link |
that increase in adrenaline, right?
link |
Again, this can be done through behavioral protocols
link |
or through pharmacology.
link |
Assuming that those behavioral protocols
link |
and pharmacology are safe for you,
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it really doesn't matter how you evoke
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the adrenaline release, because remember,
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adrenaline is the final common pathway
link |
by which particular experiences,
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particular perceptions are stamped into memory,
link |
which answers our very first question raised
link |
at the beginning of the episode,
link |
which is why do we remember anything at all, right?
link |
That was the question that we raised.
link |
Why is it that from morning till night
link |
and throughout your entire life,
link |
you have tons of sensory experience,
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tons of perceptions, why is it that some are remembered
link |
and others are not?
link |
While I would never want to distill an important question
link |
such as that down to a one molecule type of answer,
link |
I think we can confidently say,
link |
based on the vast amount of animal and human research data,
link |
that epinephrine, adrenaline,
link |
and some of the other chemicals that it acts with
link |
in concert is in fact the way
link |
that we remember particular events and not all events.
link |
If you're learning from and or enjoying this podcast,
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please subscribe to our YouTube channel.
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That's a terrific zero-cost way to support us.
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In addition, please subscribe to our podcast
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on Spotify and on Apple.
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And now on both Spotify and Apple,
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you can leave us up to a five-star review.
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Please also leave us comments and feedback
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in the comment section on our YouTube channel.
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You can also suggest future guests
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that you'd like us to cover.
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We do read all those comments.
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Please also check out the sponsors mentioned
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at the beginning of today's podcast.
link |
That's terrific, perhaps the best way
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to support this podcast.
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We also have a Patreon.
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It's patreon.com slash Andrew Huberman,
link |
and there you can support this podcast
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at any level that you like.
link |
During today's episode and on many previous episodes
link |
of the Huberman Lab Podcast, we discuss supplements.
link |
While supplements aren't necessary for everybody,
link |
many people derive tremendous benefit from them
link |
for things like enhancing sleep and focus,
link |
and indeed for learning and memory.
link |
For that reason, the Huberman Lab Podcast
link |
is now partnered with Momentous Supplements.
link |
The reason we partnered with Momentous is several fold.
link |
First of all, we wanted to have one location
link |
where people could go to access single ingredient,
link |
high quality versions of the supplements
link |
that we were discussing on this podcast.
link |
This is a critical issue.
link |
A lot of supplement companies out there
link |
sell excellent supplements,
link |
but they combine different ingredients
link |
into different formulations,
link |
which make it very hard to figure out
link |
exactly what works for you
link |
and to arrive at the minimal effective dose
link |
of the various compounds that are best for you,
link |
which we think is extremely important.
link |
And that's certainly the most scientific way
link |
or rigorous way to approach
link |
any kind of supplementation regimen.
link |
So Momentous has made these single ingredient formulations
link |
on the basis of what we suggested to them.
link |
And I'm happy to say they also ship internationally.
link |
So whether or not you're in the US or abroad,
link |
they'll ship to you.
link |
If you'd like to see the supplements recommended
link |
on the Huberman Lab Podcast,
link |
you can go to livemomentous.com slash Huberman.
link |
They've started to assemble the supplements
link |
that we've talked about on the podcast
link |
and in the upcoming weeks,
link |
they will be adding many more supplements
link |
such that in a brief period of time,
link |
most, if not all of the compounds
link |
that are discussed on this podcast
link |
will be there again in single ingredient,
link |
extremely high quality formulations
link |
that you can use to arrive
link |
at the best supplement protocols for you.
link |
We also include behavioral protocols
link |
that can be combined with supplementation protocols
link |
in order to deliver the maximum effect.
link |
Once again, that's livemomentous.com slash Huberman.
link |
And if you're not already following us
link |
on Twitter and Instagram,
link |
it's Huberman Lab on both Twitter and Instagram.
link |
There I describe science and science related tools,
link |
some of which overlap with the content
link |
of the Huberman Lab Podcast,
link |
but much of which is distinct
link |
from the content of the Huberman Lab Podcast.
link |
We also have a newsletter
link |
called the Huberman Lab Neural Network.
link |
That newsletter provides summary protocols
link |
and information from our various podcast episodes.
link |
It does not cost anything to sign up.
link |
You can go to HubermanLab.com,
link |
go to the menu and click on newsletter.
link |
You just provide your email.
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And I should point out,
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we do not share your email with anyone else.
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We have a very clear privacy policy
link |
that you can read there.
link |
And that newsletter comes out about once a month.
link |
You can also see some sample newsletters,
link |
things like the toolkit for sleep or for neuroplasticity
link |
and for various other topics covered
link |
on the Huberman Lab Podcast.
link |
Once again, thank you for joining me today
link |
to discuss the neurobiology of learning and memory
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and how to improve your memory using science-based tools.
link |
And last, but certainly not least,
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thank you for your interest in science.
link |
And I'll see you in the next one.