Understand & Improve Memory Using Science-Based Tools

1. 0:00 – 2:45

   Memory, Improving Memory

   1. AHAndrew Huberman0:00

      (Instrumental music) Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, we are discussing memory, in particular, how to improve your memory. Now, the study of memory is one that dates back many decades, and by now, there's a pretty good understanding of how memories are formed in the brain, the different structures involved, and some of the neurochemicals involved. We will talk about some of that today. Often overlooked, however, is that memories are not just about learning. Memories are also about placing your entire life into a context, and that's because what's really special about the brain, and in particular, the human brain, is its ability to place events in the context of past events, the present, and future events, and sometimes even combinations of the past and present or present and future, and so on. So, when we talk about memory, what we're really talking about is how your immediate experiences relate to previous and future experiences. Today, I'm going to make clear how that process occurs. Even if you don't have a background in biology or psychology, I promise to put it into language that anyone can access and understand. And we are going to talk about the science that points to specific tools for enhancing learning and memory. We're also going to talk about unlearning and forgetting. There are, of course, instances in which we would like to forget things, and that, too, is a biological process for which great tools exist to, for instance, eliminate or at least reduce the emotional load of a previous experience that you really did not like, or that perhaps even was traumatic to you. So today, you're going to learn about the systems in the brain and body that establish memories. You're going to learn why certain memories are easier to form than others. And I'm going to talk about specific tools that are grounded in not just one, not just a dozen, but well over a hundred studies in animals and humans that point to specific protocols that you can use in order to stamp down learning of particular things more easily. And you can also leverage that same knowledge to better forget or unload the emotional weight of experiences that you did not like. We are also going to discuss topics like deja vu and photographic memory. And for those of you that do not have a photographic memory, and I should point out that I do not have a photographic memory either, well, you will learn how to use your visual system in order to better learn visual and auditory information. There are protocols to do this, grounded in excellent peer-reviewed research. So, while you may not have a true photographic memory, by the end of the episode, you will have tools in hand, or I should say tools

2. 2:45 – 7:54

   Eight Sleep, Thesis, InsideTracker

   1. AHAndrew Huberman2:45

      in mind, or in eyes and mind, to be able to encode and remember specific events better than you would otherwise. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero-cost-to-consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is Eight Sleep. Eight Sleep makes smart mattress covers with cooling, heating, and sleep tracking. Many times on this podcast, I've talked about the incredible relationship between temperature and sleep, as well as temperature and wakefulness. Many people aren't aware of this, but waking up in the morning is in part the consequence of your body heating up, and falling asleep at night and remaining in deep sleep is in part the consequence of your body temperature dropping by one to three degrees. So, it's vitally important that the temperature of your sleeping environment is controlled. I've had trouble over the years falling and staying asleep, or I should say falling asleep hasn't been so much of an issue for me, but waking up two or three or four hours later has been an issue. Oftentimes, I'm too warm. I need to open a window. I need to adjust the temperature of the room, and so on. Eight Sleep mattress covers are terrific because you can program the specific patterns of temperature that you want in your bed, or I should say below you, coming from the mattress, throughout the night. So, I've programmed my Eight Sleep to put my mattress into a state of coolness in order to fall asleep, and then to get slightly cooler as the night goes on to get into even deeper sleep, and then to warm up as morning approaches. Um, as mentioned before, Eight Sleep mattresses can be used for cooling and heating. So, some of you may actually need to heat your mattress, and Eight Sleep's terrific for that. For me, I use Eight Sleep to keep the mattress really cool. And I have to say, even though I thought I was sleeping pretty well before, I have not experienced the sort of sleep that I've been getting with Eight Sleep until now by creating this descending temperature in the beginning part of the night, cooler, cooler, cooler, and then warming up towards morning, even has a nice little vibration function. So, I wake up now to a slightly vibrating bed. And the sleep that I'm getting is just amazing. And I feel so much better during the day as a consequence. If you'd like to try Eight Sleep, you can go to eightsleep.com/huberman and check out the Pod Pro Cover and save $150 at checkout. Eight Sleep currently ships within the USA, Canada, and the UK. Again, that's eightsleep.com/huberman to save $150 at checkout. Today's episode is also brought to us by Thesis. Thesis makes custom nootropics. And to be quite honest, I don't like the word nootropics because nootropics means smart drugs. And there really isn't a neuroscience of smart. Of course, there is this notion of intelligence, but we now know there are lots of different forms of intelligence. Also, as a neuroscientist, we don't really think about intelligence. We think about those particular types of operations that you want your brain to perform in different contexts. So, for instance, some tasks and life experiences require that you remember information better. Other tasks and life experiences and forms of learning involve focus and task switching. Others, creativity, and so on, and so on. So, the word nootropics is too much of a catchall or throwaway phrase to appeal to me. Thesis understands this, and what they've done is they've created nootropics that are each designed toward a particular end goal. For instance, they have blends for focus, blend for motivation, a blend for clarity. They use only the highest quality ingredients, things like Alpha-GPC and phosphatidylserine. I've been using Thesis for close to six months now, and I can confidently say their nootropics have been a game changer for me.I often take the Clarity formula prior to long bouts of work, meaning cognitive work, and the Energy formula prior to physical workouts. To get your own personalized nootropic starter kit, you can go online to takethesis.com/huberman, take a three-minute quiz, and Thesis will send you four different formulas to try in your first month. Again, that's takethesis.com/huberman and use the code Huberman at checkout to get 10% off your first box. Today's podcast is also brought to us by InsideTracker. InsideTracker is a personalized nutrition platform that analyzes data from your blood and DNA to help you better understand your body and help you reach your health goals. I've long been a believer in getting regular blood work done, for the simple reason that many of the factors that impact your immediate and long-term health can only be assessed from a quality blood test. One of the challenges with a lot of blood tests and DNA tests out there, however, is that you'll get the numbers back, you get information about your blood lipids, and hormones, and so forth, but there are no directives as to what to do with that information. InsideTracker has solved that problem by creating a very easy-to-use dashboard. So you'll get your numbers back, and you can see what's in range and what's out of range, and then they will point you to specific nutritional, supplementation, and behavioral tools that will allow you to bring those numbers into the proper ranges for you. And I find that immensely beneficial, because just having a bunch of data without any knowledge of what to do with that data is more overwhelming than having no data at all, frankly. If you'd like to try InsideTracker, you can go to insidetracker.com/huberman to get 20% off any of InsideTracker's plans. Again, that's insidetracker.com/huberman to get 20%

3. 7:54 – 11:12

   Sensory Stimuli, Nervous System & Encoding Memory

   1. AHAndrew Huberman7:54

      off. Okay, let's talk about memory, and let's talk about how to get better at remembering things. Now, in order to address both of those things we need to do a little bit of brain science 101 review. And I promise this will only take two minutes, and I promise that even if you don't have a background in biology, it will make sense. We are constantly being bombarded with physical stimuli. Patterns of touch on our skin, light to our eyes, light to our skin for that matter, smells, tastes, and sound waves. In fact, if you can hear me saying this right now, well, that's the consequence of sound waves arriving into your ears through headphones, a computer, or some other speaker device. Each one of and all of those sensory stimuli are converted into electricity and chemical signals by your so-called nervous system, your brain, your spinal cord, and all their connections with the organs of the body, and all the connections of your organs of the body back to your brain and spinal cord. One of the primary jobs of your nervous system, in fact, is to convert physical events in the world that are non-negotiable, right? Photons of light are photons of light. Sound waves are sound waves. There's no changing that, but your nervous system does change that. It converts those things into electrical signals and chemical signals, which are the language of your nervous system. Now just because you're being bombarded with all this sensory information and it's being converted into a language that neurons and the rest of your nervous system can understand, does not mean that you are aware of it all. In fact, you are only going to perceive a small amount of that sensory information. For instance, if you can hear me speaking right now, you are perceiving my voice, but you are also most likely neglecting the feeling of the contact of your skin with whichever surface you happen to be sitting or standing on. So it is only by perceiving a subset, a small fraction of the sensory events in our environment that we can make sense of the world around us. Otherwise, we would just be overwhelmed with all the things that are happening in any one given moment. Now memory is simply a bias in which perceptions will be replayed again in the future. Any time you experience something, that is the consequence of specific chains of neurons that we call neural circuits being activated. And memory is simply a bias in the likelihood that that specific chain of neurons will be activated again. So for instance, if you can remember your name, and I certainly hope that you can, well, that means that there are specific chains of neurons in your brain that represent your name. And when those neurons connect with one another and communicate electrically with one another in a particular sequence, you remember your name. Were that particular chain of neurons to be disrupted, you would not be able to remember your name. Now this might seem immensely simple, but it raises this really interesting question, which we talked about before, which is, why do we remember certain things and not others? Because according to what I've just said, as you go through life, you're experiencing things all the time. You're constantly being bombarded with sensory stimuli. Some of those sensory stimuli you perceive, and only some of those perceptions get stamped down as memories. Today I'm going to teach you how certain things get stamped down as memories. And I'm going to teach you how to leverage that process in order to remember the information that you want far better.

4. 11:12 – 13:46

   Context & Memory Formation

   1. AHAndrew Huberman11:12

      Now even though I've told you that a memory is simply a bias in the likelihood that a particular chain of neurons will be activated in a particular sequence again and again, it doesn't operate on its own. In fact, most of what we remember takes place in a context of other events. So for instance, you can most likely remember your name, and yet you're probably not thinking about when it was that you first learned your name. Right? This u- generally happens when we are very, very young children. And yet I'm guessing you could probably remember a time when someone mispronounced your name or made fun of your name, or as the case was for me, I got to the third grade and there were two Andrews. And sadly for me, I lost the coin flip that allowed me to keep Andrew. And from about third grade until about, uh, 12th grade people called me Andy, which I really did not prefer. So if you call me Andy in the comments, I'll delete your comment. Just kidding. Doesn't bother me that much, but eventually I reclaimed Andrew as my name. (laughs) Well, it was mine to begin with and throughout, but I started going by Andrew again.Why do I say this? Well, there's a whole context to my name for me, and there may or may not be a whole context to your name for you. But presumably, if you ask your parents why they named you your given name, you'll get a context, etc. That context reflects the activation of other neural circuits that are also related to other events in your life. Not just your name, but probably your siblings' names, and who your parents are, and on, and on, and on. And so the way memory works is that each individual thing that we remember or that we want to remember is linked to something by either a close, a medium, or a very distant association. This turns out to be immensely important. I know many of you will read or will encounter programs that are designed to help you enhance your memory. You know, you have these, uh, phenoms that can remember 50 names in a, in a room full of people, or they can remember a bunch of names of novel objects, or in, maybe even in different languages, and oftentimes that's done by association. So people will come up with little mental tricks to, you know, either link the sound of a word, or the meaning of a word in some way that's meaningful for them and will enhance their memory. That can be done and is impressive when we see it, and for those of you who can do that, congratulations. Most of us can't do that, or at least it requires a lot of effort and training. However, there are things that we can do that leverage the natural biology of our nervous system to enhance learning and memory of particular perceptions, and particular information.

5. 13:46 – 17:11

   Tool: Repetition, Improving Learning & Memory

   1. AHAndrew Huberman13:46

      Let's first just talk about the most basic ways that we learn and remember things, and how to improve learning and memory, and the most basic one is repetition. Now, the study of memory and the role of repetition actually dates back to the late 1800s, early 1900s when Ebbinghaus developed the first so-called learning curves. Now, learning curves are simply what results when you quantify how many repetitions of something are required in order to remember something. In fact, it's been said that Ebbinghaus liberated the understanding of learning from the philosophers by generating these learning curves. What do we mean by that? Well, before Ebbinghaus came along, learning and memory were thought to be philosophical ideas, right? Ebbinghaus came along and said, "Well, let's actually take some measurements. Let's measure how well I can remember a sequence of words or a sequence of numbers if I just repeat them." So what Ebbinghaus did is he would take a sequence of numbers or words on a page, and he would read them, and then he would take a separate sheet of paper, and we have to presume he didn't cheat, and he would write down as many of them as he could, and he would try and keep them in the same sequence. Then he would compare to the original list, and he would see how many errors he made, and he would do this over, and over, and over again. And as you would expect, early in the t- training and the learning, it took a lot more repetitions to get the sequence correct. And over time, it took fewer sequences. And he referred to that difference in the initial number of repetitions that he had to perform versus the later number of repetitions that he had to perform as a so-called savings. So he literally thought of the brain as having to generate a kind of a currency of effort, and he talked about savings as the reduction in the amount of effort that he had to put forward in order to learn information, and what he got was a learning curve, and you can imagine what that learning curve looked like. It was at a very sharp peak at the beginning that dropped off over time, and of course, he remembered all this meaningless information. But even though the information might have been meaningless, the experiment itself and what Ebbinghaus demonstrated was immensely meaningful, because what it said was that with repetition, we can activate particular sequences of neurons, and that repeated activation lays down what we call a memory. And that might all seem like a big duh, but prior to Ebbinghaus, none of that was known. Now, I should also say Ebbinghaus, because of when he was alive, was not aware of these things that we call neural circuits. It was in 1906 that Golgi and Cajal got the Nobel Prize for actually showing that neurons are independent cells connected by synapses, these little gaps between them where they communicate. So he may have been aware of that, but the whole notion of neural circuits hadn't really come about. Nevertheless, what the Ebbinghaus learning curves really established was that sheer repetition, just repeating things over, and over, and over again is sufficient to learn. Something that no doubt had been observed before, but it had never been formally quantified. Now, if we look at that result, there's something really important that lies a little bit cryptic, that's not so obvious to most people, which is the information that he was trying to learn wasn't any more interesting the second time than it was the first, probably was even less interesting, and less and less interesting with each repetition. And yet it was sheer repetition that allowed him to remember.

6. 17:11 – 20:50

   Co-Activation and intensity Neuron Activation

   1. AHAndrew Huberman17:11

      Now, sometime later, in the early to mid-1920s, a psychologist in Canada named Donald Hebb came up with what was called Hebb's postulate, and Hebb's postulate, broadly speaking, is this idea that if a sequence of neurons is active at the same time, or at roughly the same time, that that would lead to a strengthening of the connections between those neurons. And many, many decades of experimentation later, we now know that postulate to be true. Neurons themselves are not smart. They don't have knowledge, so every memory is the consequence, as I told you before, of the repeated activation of a particular chain of neurons. And what Ebbinghaus showed through repetition and what Donald Hebb proposed, and was eventually verified through experimentation on animals and humans, was that if you encourage the co-activation of neurons, meaning have neurons fire at roughly the same time, they will strengthen their connections. It leads to a bias... ... in the probability that those neurons will be active again. Now, this is vitally important, because nowadays we hear a lot about how memories are the consequence of new neurons added in the brain, or that-Every time you learn something, a new connection in your brain forms. Well, sorry to break it to you, but that's simply not the case. Most of the time, and I want to emphasize most, not all, but most of the time when we learn something, it's because existing neurons, not new neurons, but existing neurons strengthen their connection through co-activation over and over and over, through repetition, or, and this is a very important or, or through very strong activation once and only once. In fact, there's something called one trial learning whereby we experience something and we will remember that thing forever. This is often most associated with negative events, and I'll explain why in a few minutes, but it can also be associated with positive events, like the first time you saw your romantic partner, or something that happened with that romantic partner, or the first time that you saw your child, or any other positive event, as well as any other extremely negative event. So again, both repetition, and I guess we could label it intensity, but what we really mean when we say intensity is strong activation of neurons can lay down these traces, these circuits that are far more likely to be active again than had there not been repetition or not some strong activation of those circuits. So with that in mind, let's return to the original contrarian question that I raised before, which is, why do we remember anything? Every day you wake up, your neurons in your brain and body are active, different neural circuits are active, and yet you only remember a small fraction of the things that happen each day. And yet you retain a lot of information from previous days and the days before those, and so on. It is only with a lot of repetition or with extremely strong activation of a given neural circuit that we will create new memories. And so in a few minutes, I'll explain how to get extremely strong activation of particular neural circuits. Repetition is pretty obvious. Repetition is repetition. But in a few minutes, I'll illustrate a whole set of experiments and a whole set of tools that point to how you can get extra strong activation of a given neural circuit as it relates to learning so that you will remember that information perhaps not just with one trial of learning, but certainly with far fewer repetitions than would be required otherwise.

7. 20:50 – 25:40

   Different Types of Memory

   1. AHAndrew Huberman20:50

      Before we go any further, I want to preface the discussion by saying that there are a lot of different kinds of memory. In fact, were you to take a voyage into the neuroscience and/or psychology of memory, you would find an immense number of different terms to describe the immense number of different types of memory that researchers focus on. But for sake of today's discussion, I really just want to focus on short-term memory, medium-term memory, and long-term memory. And while there's still debate, as is always the case with scientists, frankly, about the exact divisions between short-term, medium, and long-term memory, we can broadly define short-term memory and long-term memory, and we can describe a couple different types of those that I think w- you can relate to in your everyday life. The most common form of short-term memory that we're going to focus on is called working memory. Working memory is your ability to keep a chain of numbers in mind for some period of time, but the expectation really isn't that you would remember those numbers the next day, and certainly not the next week. So a good example would be a phone number. If I were to tell you a phone number, 493-2938, well, you could probably remember it, 493-2938, but if I came back tomorrow and asked you to repeat that chain of numbers, most likely you would not. Unless, of course, we used a particular tool to stamp down that memory into your mind and commit it to long-term memory. Now, of course, in this day and age, most people have phone numbers programmed into their phone. They don't really have to remember the exact numbers. It's usually done by contact, uh, identity, and so forth. So a different example that some of you are probably more familiar with would be those security codes. So you try and log on to an app or a website and it asks you for a security code that's been sent to your text messages, and then you can either plug that in directly in some cases, or you have to remember that short sequence of anywhere usually from six to seven, sometimes eight numbers. Your ability to do that, to switch back and forth between web pages or apps and plug in that number by remembering the sequence and plugging it in by texting or, or keying it in on your keyboard, that's a really good example of working memory. Long-term memory of the sort that we're going to be talking a lot about today is your ability to commit certain patterns of information, either cognitive information or motor information, right, the ability to move your limbs in a particular sequence, over long periods of time, such, uh, such that you could remember it a day, or a week, or a month, or maybe even a year or several years later. So we've got short-term memory and long-term memory, and we've got this working memory which is kind of keeping something online, but then discarding it. Okay? Not online on a computer, but online within your brain. There are also two major categories of memory that I'd like you to know about. One is explicit memory. So this is not necessarily explicit of the sort that you're used to thinking about, but rather the fact that you can declare you know something. So you have an explicit memory of your name. Presumably you have an explicit memory of the house or the apartment that you grew up in. You know something and you know you know it, and you can declare it. So I can ask you, "What was the color of the first car that you owned?" Or, "What is the color of your romantic partner's hair?" These sorts of things. That's an explicit declarative memory. But you also have explicit procedural memories. Now, procedural memories, as the name suggests, involve action sequences. The simplest one, it's almost ridiculously simple, is walking. If I say, "How is it that you walk from one room to the other?" You'd probably say, "Well, I go that direction, I turn left." If I say, "No, no, no, no, how is it exactly that you do it?" You'd say, "Well, I move my left foot, then my right foot, then my left foot." And you could describe that. So it's an explicit procedural memory, so much so that if you were going to teach a young toddler how to walk, you would probably say, "Okay, good, good, try, okay," and you, you know, probably that's going to be pre-language for the toddler.But you're going to encourage them to move one leg then the other. And you're going to encourage and reward them for moving one leg the, then the other, because you have an explicit procedural memory of how to walk. Okay? Almost ridiculously simple, maybe even truly ridiculously simple, but nonetheless, when you think about it in the context of neural circuits and neural firing, pretty amazing. Even more amazing is the fact that all explicit memories, both declarative and procedural explicit memories, can be moved from explicit to implicit. What do I mean by that? Well, in the example of walking, you might have chuckled a little bit or kind of sh- shook your head and said, "That's a ridiculous thing to ask. How do I walk from one room to the next? I just walk. I just do it." Ah, well, what is just do it? What it is, is that you have an implicit understanding, meaning your nervous system knows how to walk without you actually having to think about what you know about how to walk. You just get up out of your chair, or you get up out of bed, and you walk.

8. 25:40 – 28:00

   Memory Formation in the Brain, Hippocampus

   1. AHAndrew Huberman25:41

      In the brain, you have a structure. In fact, you have one on each side of your brain. It's called the hippocampus. The hippocampus literally means sea horse. Anatomists like to name brain structures after things that they think those brain structures resemble. When I look at the hippocampus, frankly, it doesn't look like a sea horse, which either reflects my lack of understanding of what a sea horse really looks like, a visual deficit, or I think it's fair to say that those anatomists were using a little bit of creative, um, elaboration when thinking about what the hippocampus looks like. Nonetheless, it is a curved structure. It has many layers. It's been described by my colleague, Robert Sapolsky, and by others as looking more like a jelly roll or a cinnamon roll, is what it looks like to me. Uh, and if you were to take one cinnamon roll, chop it down the middle, so now you've got two half cinnamon rolls. And rather than put them back together in the configuration they were before, you just slide one down so that you've got essentially two Cs, two C-shaped halves of the cinnamon roll, and you push them together, right, slightly offset from one another. Well, that's what the hippocampus looks like to me. And I think that's a far better description of its actual physical structure. But I guess if you were to use that physical structure as the name, well, then you'd have to open up a brain atlas and it would be called two half-C cinnamon rolls stuffed halfway together, so that's not very good. So I guess sea horse will work. Hippocampus is the name of the structure, and it is the site in your brain, and again, you have one on each side of your brain, in which explicit declarative memories are formed. It is not where those memories are stored and maintained. It is where they are established in the first place. In contrast, implicit memories, right? These subconscious memories are formed and stored elsewhere in the brain, mainly by areas like the cerebellum, but also the neocortex, the kind of outer shell of your brain. The cerebellum is, it literally means mini brain. And it does in fact look like a mini brain, and is in the back of the brain. And the neocortex is the outer part of the brain that covers all the other stuff. So the hippocampus is vitally important for establishing these new declarative memories of what you know and what you know how to do.

9. 28:00 – 31:49

   Hippocampus, Role in Memory & Learning, Explicit vs. Implicit Memory

   1. AHAndrew Huberman28:00

      Now, in order to really understand the role of the hippocampus and memory, in particular, explicit declarative and explicit procedural memory, and to really understand how that's distinct from implicit declarative and implicit procedural memories, we have to look to a clinical case. And the clinical case I'm referring to is a patient who went by the name HM. Patients go by their initials in order to maintain confidentiality of their real identity. HM had what's called intractable epilepsy. So he would have these really dramatic so-called grand mal seizures or drop seizures. For those of you that know somebody with epilepsy or that have epilepsy, uh, you might be familiar with this. You can have petit mal seizures, which are minor seizures. You can have tonic-clonic seizures, which are sometimes not even detectable. You can have absence seizures where people will just stop. It's almost as if their brain kind of goes on pause and they'll just stop there. It was reported actually that Einstein had absent seizures, although I don't know that that's ever really been confirmed neurologically. Grand mal seizures are extremely severe. And that's what HM had. So he could just be going about his day and maybe even cooking or doing something, driving, operating any kind of machinery, and then all of a sudden he would just have a drop seizure. So he would just physically drop and go into a grand mal seizure. So convulsing of the whole body, loss of consciousness, et cetera. Or he would feel it coming on. Oftentimes people with epilepsy can feel the epileptic seizure coming on, kind of like a wave from the back of the brain. And sometimes they can get to a safe circumstance, but not always. And so the frequency and the intensity of his seizures were so robust that the neurosurgeons and neurologists decided that they needed to locate the origin, what they call the foci of those seizures and remove that brain tissue. Because the way seizures work is they spread out from that fo- focus or that foci of brain tissue. And unfortunately for HM, the focus of his seizures was the hippocampus. So after a lot of deliberation, a neurosurgeon, in fact, one of the most famous neurosurgeons in the world at that time, made what are called electrolytic lesions, actually burned out the hippocampus in the brain of HM. And as a consequence, he lost all explicit memory. Now, the consequence of this was that he couldn't exist in normal everyday life like most people. So he had to live mostly, not, not entirely, but mostly in a kind of hospital setting. And I've talked to several people who have, who I should say who met HM directly because he's no longer alive, but an interaction with him might look like the following.He would walk up to you just fine. You wouldn't know that he had any kind of brain damage. He could walk fine. He could speak fine and you'd say, "Hi, I'm Andrew." And he'd say, "Hi, I'm..." whatever his name happened to be. H- he wouldn't say H.M., but he'd probably say his real name. And then perhaps someone new would walk into the room. He might turn around, look at that person, as any of us might do. Then turn around back to me and say, "Hi, what's your name?" And if I were to say, "Well, I just told you my name, uh, and you just told me your name. Do you remember that?" He'd say, "I'm sorry. I don't remember any of that. What's your name?" So you had to go through this over and over again. So a complete lack of explicit declarative memory. Now he did have some memory for previous events in his life that dated way back. Okay? Again, hinting at the idea that memories are not necessarily stored in the hippocampus, they're just formed in the hippocampus. So once they've moved out of the hippocampus to other brain areas, he could still keep those memories. They're in a different database, if you will. They're in a different pattern of firing of other neural circuits. But he couldn't form new memories. Now there's some

10. 31:49 – 36:44

    Emotion & Memory Enhancement

    1. AHAndrew Huberman31:49

       very important and interesting twists on what H.M. could and could not do in terms of learning and memory that teach us a lot about the brain. In fact, I think most neuroscientists would agree that this unfortunate case of H.M.'s epilepsy and the subsequent neurosurgery that he had, taught us much of what we know, or at least think about, in terms of human learning and memory. For instance, as I mentioned before, he still had implicit knowledge. He knew how to walk. He knew how to do certain things like make a cup of coffee. He knew the names of people that he had met much earlier in his life, and so on. And yet he couldn't form new memories. Now in violation to that last statement, there were some elements of H.M.'s emotionality that suggests that there was some sort of residual capacity to learn new information, but it wasn't what we normally think of as explicit, declarative, or procedural memory. For instance, it's been reported, or it's been said I should say, because I don't know that the studies were ever done with intense physiological measurements, that if you were to tell H.M. a joke and he thought it was funny, he would laugh really hard. So he liked jokes so you'd tell him, you'd say, "H.M., I want to tell you a joke." You'd tell him a joke and he'd laugh really hard. Then you could leave the room, come back, and tell him the same joke again. Now keep in mind, he did not remember that you told him the joke previously. And the second time he would laugh a little bit less, and then you'd leave the room, come back again. Say, "Hi, I'm Andrew." He'd say, "Oh, nice to meet you," because as you r- know, uh, as you recall, because you can recall things, but he couldn't recall things. He didn't know that he just met you, or at least he couldn't remember it. You tell him the joke a third time or a fourth time, and with each subsequent telling of the joke, he found it a little less funny. Just as, keep this in mind folks, if you tell a joke and you get a big laugh, don't tell it again. At least not immediately. Not to the same person or the same crowd, because the second time it's a little less funny, and the third time it's a little less funny. And that actually has to do with a whole element of dopamine and its relationship to surprise, and that's the topic of a future podcast where we talk all about humor and novelty in the brain. But the point being that certain forms of memory seem to exist in a kind of phantom-like way within H.M.'s brain. What do I mean by that? Well, this underscores the fact that he had an implicit memory of having heard the joke before, and it suggests that humor, or at least what we find funny, is somehow more related to procedures similar to walking or a motor ability than it is to the precise content of that joke. All right. That's a little bit of an abstract concept, but the point is that H.M. lacked explicit declarative memory. He couldn't tell you what he had just heard. He could not learn new information, and he couldn't tell you how to do something unless he had learned how to do that something many years prior. Now there have been a lot of other patients besides H.M. that have had brain lesions due to epilepsy, or I should say due to surgeries to treat epilepsy, due to strokes, due to, um, sadly gunshot wounds and other forms of what we call infarcts. Infarct, I-N-F-A-R-C-T. Infarct is the word we use to describe damage to a particular brain region. And many different patients with many different patterns of infarct have taught us a lot about how memory and other aspects of the brain work. H.M. really teaches us that what we know and what we are able to do is the consequence of things that we are aware of and learnings that have been passed off into subconscious knowledge, that our body knows, our brain knows, but we don't know exactly how we know that thing. And I tell you the story about H.M.'s ability to understand a joke, but that with repeated telling of a joke it has less and less and less of an impact in creating a sense of laughter, of humor in H.M. Not as just an anecdote to flesh out his story, but because emotion itself turns out to be the way in which we can enhance memories, even if those are memories for things that are not funny, are not intensely sad, are not immensely happy, or don't evoke a really strong emotional response, or even any remote emotional response. And the reason for that is that emotions, just like perception, just like sensation, are the consequence of particular neurochemicals being present in our brain and body. And as I'm going to tell you next, there are particular neurochemicals that you can leverage in order to learn specific information faster and to remember it for a much longer period of time, maybe even forever, and you can do that by leveraging the relationship in your nervous system between your brain and your body, and your body back to your brain.

11. 36:44 – 41:42

    Tool: Emotion Saliency & Improved Memory

    1. AHAndrew Huberman36:44

       So let's talk about tools for enhancing memory. Now there's one tool that is absolutely clear works.And it's always worked, it works now, and it will work forever. And that's repetition. The more often that you perform something or that you recite something, the more likely you are to remember it in the future. (smacks lips) And while that might seem obvious, it's worth thinking about what's happening when you repeat something. But when I say what's happening, I mean, at the neural level. What's happening is that you are encouraging the firing of particular chains of neurons that reside in a particular circuit, right? So a particular sequence of neurons playing neuron A, B, C, D, played in that particular sequence over and over and over again. And with more repetitions you get more strengthening of those nerve connections. Now, repetition works but the problem for most people is that they either don't have the patience, they don't have the time, and sometimes they literally don't have the time because they've got a deadline on something that they're trying to remember and learn, or they simply would like to be able to remember things better in general, remember them more quickly. This process of accelerating repetition-based learning so that your learning curve doesn't go from having to perform something a thousand times and then gradually over time it's a thousand, 750 times a day, 500 times a day, 300 times a day and down to no repetitions, right? You can just perform that thing the first time and every time. Well, there is a way to shift that curve so that you can essentially establish stronger connections between the neurons that are involved in generating that memory or behavior more quickly. How do you do that? Well, in order to answer that we have to look at the beautiful work of James McGaugh and Larry Cahill. James McGaugh and Larry Cahill did a number of experiments over several decades really, based on a lot of animal literature, but mainly focused on humans, that really established what's required to get better at remembering things and to do so very quickly. I want to talk about one experiment that they did that was particularly important. And we will provide a link to this paper. It's some years old now, but the results still hold up. In fact, the results establish an entire field of memory in neuroscience and psychology. What they did is they had human subjects come into the laboratory and to read a short paragraph of about 12 sentences. And the key thing is that some subjects read a paragraph that was pretty mundane. The content, the information within the paragraph was all related to the content of the previous sentence so it was a cogent paragraph. Right? It just wasn't meaningless scramble of words. But it described a kind of mundane set of circumstances. Maybe it would be a story about someone who walked into a room, sat down at a desk, wrote for a little bit, then got up and had lunch. You know, just kind of mundane information, not very interesting. Another group of subjects read also a 12 sentence paragraph, but that paragraph included a subset of sentences that had a lot of emotionally intense language or that had language that could evoke an emotionally intense response in the person reading it. So it might have talked about a car accident or a very intense surgery. But it also could be positive stuff. Things like a birthday party or a celebration of some other kind or a big sports win. So in other words you have two conditions of this study. People either read a boring paragraph or they read a really emotionally laden paragraph. And again, the emotions could either be positive or negative emotions. Subjects left the laboratory and sometime later they were called back to the laboratory. And I should say at no point in the experiment did they know they were part of a memory experiment. Okay? They don't know why they're reading this paragraph. They came in either for class credit or to get paid. That's typically how these things are done on college campuses or elsewhere. They come back into the lab and they would get a pop quiz. They would be asked to recall the content of the paragraph that they had read previously. Now, as is probably expected, perhaps even obvious to you, the subjects that read the emotionally intense paragraph remembered far more of the content of that paragraph and were far more accurate in their remembering of that information. Now, that particular finding wasn't very novel. Many people had previously described how emotionally intense events are better remembered than non-emotionally intense events. In fact, way back in the 1600s, Francis Bacon, who's largely credited with developing the scientific method, said, quote, "Memory is assisted by anything that makes an impression on a powerful passion, inspiring fear, for example, or wonder, shame, or joy." Francis Bacon said that in 1620. So Jim McGaugh

12. 41:42 – 47:14

    Conditioned-Placed Avoidance/Preference, Adrenaline

    1. AHAndrew Huberman41:42

       and Larry Cahill were certainly not the first to demonstrate or to conceive of the idea that emotionally laden experiences are more easily remembered than other experiences. However, what they did next was immensely important for our understanding of memory and for our building of tools to enhance learning and memory. What they did was they evaluated the capacity for stress and for particular neurochemicals associated with stress to improve our ability to learn information. Not just information that is emotional, but information of all kinds. So I'm going to describe some experiments done in animal models, just very briefly, and then experiments done on human subjects because McGaugh worked mainly on animals, also human subjects. Larry Cahill almost exclusively on human subjects. If you take a rat or a mouse and put it in an arena where at one location the animal receives an electrical shock and then you come back the next day, you remove the shock evoking device and you let the animal move around that arena, that animal will quite understandably avoid the location where it was shocked, so-called conditioned place aversion.That effect of avoiding that particular location occurs in one trial. That's a good example of one trial learning. So somehow the animal knows that it was shocked at that location. It remembers that. It is a hippocampal dependent learning. So animals that lack a hippocampus or who have their hippocampus pharmacologically or otherwise incapacitated will not learn that new bit of information. But for animals that do, they remember it after the first time and every time, unless you are to block the release of certain chemicals in the brain and body. And the chemicals I'm referring to are epinephrine, adrenaline, and to some extent the corticosteroids, things like cortisol. Now we know that the effect of getting one trial learning somehow involves epinephrine, at least in this particular experimental scenario. Because if researchers do the exact same experiment, and they have done the exact same experiment, but they introduce a pharmacological blocker of epinephrine so that epinephrine is released in response to the shock but it cannot actually bind to its receptors and have all of its biological effects, well then the animal is perfectly happy to tread back into the area where it received the shock. It's almost as if it didn't know, or we have to assume they didn't remember that it received the shock at that location. So it all seems pretty obvious when you hear it. Something bad happens in a location, you don't go back to that location. So that's conditioned place avoidance, but it turns out that the opposite is also true. Meaning for something called conditioned place preference you can take an animal, put it into an arena, feed it or reward it somehow at one location in that arena, so you can give a hungry rat or mouse food at one particular location, take the animal out, come back the next day. No food is introduced, but it will go back to the location where it received the food. Or you can do any variant of this. You can make the arena a little bit chilly and provide warmth at that location. Or you can take a male animal, and it turns out male rats and mice will mate at any point, or a female animal that's at the particular so-called receptive phase of her mating cycle, and give them an opportunity to mate at a given location. They'll go back to that location and wait and wait. This is perhaps why people go back to the same bar, or the bar, seat at the bar, or the same restaurant and wait for, 'cause of the one time they, you know, things worked out for them, what, whatever the context was. Conditioned place preference. Conditioned place preference, as with conditioned place avoidance, depends on the release of adrenaline. Right? It's not just about stress. It's about a heightened emotional state in the brain and body. Okay, this is really important. It's not just about stress. You can get one trial learning for positive events, conditioned place preference, and you can get one trial learning for negative events. Here I say positive and negative. I'm putting what's called valence on. I'm making a value judgment about whether or not the animal liked it or didn't like it, and we have to presume what the animal liked or didn't like and how it felt. But this turns out all to be true for humans as well. We know that because McGaugh and Cahill did experiments where they gave people a boring paragraph to read, and only a boring paragraph to read, but one group of subjects was asked to read the paragraph and then to place their arm into very, very cold water. In fact, it was ice water. We know that placing one's arm into ice water, especially if it's up to the shoulder or near to it, evokes the release of adrenaline in the body. It's not an enormous release, but it's a significant increase, and yes, they measured adrenaline release. In some cases, they also measured for things like cortisol, et cetera. And what they found is that if one evokes the release of adrenaline through this arm into ice water approach, the information that they read previously, just a few minutes before, was remembered. It was retained as well as emotionally intense information. But keep in mind, the information that they read was not interesting at all, or at least it wasn't emotionally laden. This had to be the effect of adrenaline released into the brain and body, because if they blocked the release or the function of adrenaline in the brain and/or body, they could block this

13. 47:14 – 49:35

    Adrenaline & Cortisol

    1. AHAndrew Huberman47:14

       effect. Now the biology of epinephrine and cortisol are a little bit complex, but there's some nuance there that's actually interesting and important to us. First of all, adrenaline is released in the body and in the brain. It's released in the body from the adrenals. Remember, epinephrine and adrenaline are the same thing. Cortisol is also released from the adrenal glands, these two little glands that ride atop our kidneys. But it can't cross into the brain. It only has what we call peripheral effects, quickening of the heart rate. Right? Changes to patterns of blood flow. Changes in our patterns of breathing, in general makes our breathing more shallow and faster, in general makes our heart beat more quickly, et cetera. Within our brain, we have a little brain area called locus coeruleus, which is in the back of the brain, which has the opportunity to sprinkler the rest of the brain with the neuromodulator epinephrine, adrenaline, as well as norepinephrine, a related neuromodulator, and to essentially wake up or create a state of alertness throughout the brain. So it's a very general effect. The reason we have two sites of release is because these neurochemicals do not cross the blood-brain barrier, and so waking up the body with adrenaline and waking up the brain are two separate so-called parallel phenomena. Cortisol can cross the blood-brain barrier because it's lipophilic, meaning it can move through fatty tissue. And we'll get into the biology of that in another episode, but cortisol in general is released and has much longer term effects, and as I've just told you, can permeate throughout the brain and body. Adrenaline has more local effects, or at least is segregated between the brain and the body. This will turn out to be important later. The important thing to keep in mind is that it is the emotionality evoked by an experience, or to be more precise, it is the emotional state that you are in after...... you experience something that dictates whether or not you will learn it quickly or not. This is absolutely important in terms of thinking about tools to improve your memory. And no, I am not going to suggest that every time you want to learn something you plunge your arm into ice water. Why won't I suggest that? Well, it will induce the release of adrenaline, but there are better ways to get that adrenaline release. Before I explain exactly what those tools are, I want to tamp down the biology of how all this works. Because in that understanding you will have access to the best possible tools to improve your memory.

14. 49:35 – 53:03

    Accelerating the Repetition Curve & Adrenaline

    1. AHAndrew Huberman49:35

       First of all, McGaugh and Cahill were excellent experimentalists. They did not just establish that you could quicken the formation of a memory by accessing material that was very emotionally laden or creating an emotional high adrenaline state after interacting with some things, some words, some persons, some information. They also tested whether or not that whole effect could be blocked by blocking the emotional state or by blocking adrenaline. So what they did was they had people read paragraphs that were, either had a lot of emotional content, or they had people read paragraphs that were pretty boring, but then had them put their arm into ice water. And I should say they did other experiments too to increase adrenaline. There were even some shock experiments that were done by other groups. Any number of things to evoke the release of adrenaline. Even people taking drugs that increase adrenaline. But then they also did what are called blocking experiments. They did experiments where they had people get into a highly emotional state from reading highly emotional material, or they got people to get into a highly emotional neurochemical state by reading boring material and then taking a drug to increase adrenaline or an ice bath or a shock. And then they also administered a drug called a beta blocker to block the effect of adrenaline and related chemicals in the brain and body. And what they found is that even if people were exposed to something really emotional or had a lot of adrenaline in their system because they received a drug to increase the amount of adrenaline, two manipulations that normally would increase memory, keep that in mind, if they gave them a beta blocker which reduced the response to that adrenaline, right? So no quickening of the heart rate, no quickening of the breathing, no increase in the activity of locus coeruleus and these kind of wake up signals to the rest of the brain, well then the material wasn't remembered better at all. What this tells us is that, yes, Francis Bacon was right. McGaugh and Cahill were right. Hundreds if not thousands of philosophers and psychologists and neuroscientists were right in stating and in thinking that high emotional states help you learn things. But what McGaugh and Cahill really showed, and what's most important to know, is that it is the presence of high adrenaline, high amounts of norepinephrine and epinephrine and perhaps cortisol as well, as you'll soon see, that allows a memory to be stamped down quickly. It is not the emotion. It is the neurochemical state that you go into as a consequence of the emotion. And it's very important to understand that while those two things are related, they are not one and the same thing. Because what that means is that were you to evoke the release of epinephrine, norepinephrine, and cortisol, or even just one or two of those chemicals after experiencing something, you are stamping down the experience that you just previously had. Now this is fundamentally important and far and away different than the idea that we remember things because they're important to us or because they evoke emotion. That's true, but the real reason, the neurochemical reason, the mechanism behind all that is these neurochemicals have the ability to strengthen neural connections by making them active just once. There's something truly magic about that neurochemical cocktail that removes the need for repetition.

15. 53:03 – 1:00:50

    Tool: Enhancing Learning & Memory - Caffeine, Alpha-GPC & Stimulant Timing

    1. AHAndrew Huberman53:03

       Okay, so let's apply this knowledge. Let's establish a scientifically grounded set of tools. Meaning tools that take into account the identity of the neurochemicals that are important for enhancing learning, and the timing of the release of those chemicals in order to enhance learning. When I first learned about the results of McGaugh and Cahill I was just blown away. I was also pretty upset, but not with them. I was upset with myself, because I realized that the way that I'd been approaching learning and memory was not optimal. In fact, it was probably in the opposite direction to the enhanced protocol for learning and memory that I'm going to teach you today. My typical mode of trying to learn something while I was in college or while I was in graduate school, or as a junior professor or even a tenured professor, was to sit down to whatever it is I was going to try and learn, perhaps even memorize. Or if it was a physical skill, move to whatever environment I was going to learn that physical skill in. And prior to that to make sure that I was hydrated, 'cause that's important to me, and certainly can contribute to your brain's ability to function and your body's ability to function, and general patterns of alertness, but also to caffeinate. Right? I would have a nice strong cup of coffee or espresso. I would have a nice strong cup of yerba mate. And I still drink coffee or yerba mate very regularly. I drink them in moderation I think, certainly for me. But typically I would drink those things before I would engage in any kind of attempt to learn or memorize or to acquire a new skill. Now caffeine in the form of coffee or yerba mate or any other form of caffeine does create a sense of alertness in our brain and body. And it does that through two major mechanisms. The first mechanism is by blocking the effects of adenosine. Adenosine is a molecule that builds up in the brain and body the longer that we are awake and it's largely what's responsible for our feelings of sleepiness and fatigue when we've been awake for a very long time.Caffeine essentially acts to block the effects of adenosine. It's a competing agonist, so not to get technical, but it binds to the receptor for adenosine for some period of time and prevents adenosine from having its normal pattern of action, and thereby reduces our feelings of fatigue. But it also increases state of alertness. So while it's reducing fatigue, it's also pushing on neurochemical systems in order to directly increase our alertness and it does that in large part by increasing the transmission of epinephrine, adrenaline, in the brain and body. It also has this interesting effect of up-regulating the number and/or efficiency, or we say the efficacy of dopamine receptors, such that when dopamine is present and is a molecule that increases motivation and craving and pursuit, that dopamine can have a more potent effect than it would otherwise. So caffeine really hits these three systems. It hits other systems too, but it mainly hit- Reduces fatigue by reducing adenosine, increases alertness by increasing epinephrine release or adrenaline release, I should say, both from the adrenals in your body and from locus coeruleus within the brain. And it can, in parallel to all that, increase the action or the efficacy of the action of dopamine. So my typical way of approaching learning and memory would be to drink some caffeine and then focus really hard on whatever it is that I'm trying to learn, try and eliminate distractions, and then hope, hope, hope or try, try, try to remember that information as best as I could. And frankly, I felt like it was working pretty well for me. And typically if I leveraged other forms of pharmacology in order to enhance learning and memory, things like Alpha-GPC or phosphatidylserine, I would do that by taking those things before I sat down to learn a particular set of information, or before I went off to learn a particular physical skill. Now, for those of you out there listening to this, you're probably thinking, "Well, okay, the results of McGaugh and Cahill pointed to the fact that having adrenaline released after learning something enhanced learning of that thing, but a lot of these things like caffeine or Alpha-GPC can increase epinephrine and adrenaline or dopamine or other molecules in the brain and body that can enhance memory for a long period of time. So it makes sense to take it first or even during learning, and then allow that increase to occur and the increase will occur over a long period of time and will enhance learning and memory." And while that is partially true, it is not entirely true, and it turns out it's not optimal. Work that was done by the McGaugh Laboratory and other laboratories evaluated the precise temporal relationship between neurochemical activation of these pathways and learning and memory. What they did is they had animals and/or people, depending on the experiment, take a drug, could be caffeine, could be in pill form, something that would increase adrenaline or related molecules that create this state of alertness that are related to emotionality, and they had them do it either an hour before, 30 minutes before, 10 minutes before, or five minutes before learning or during the bout of learning, right? The reading of the information or the performing of the skill that one is trying to learn. Or five minutes, 10 minutes, 15 minutes, 30 minutes, et cetera, afterwards. So they looked very precisely at when exactly is best to evoke this adrenaline release. And it turns out that the best time window to evoke the release of these chemicals, if the goal is to enhance learning and memory of the material, is either immediately after or just a few minutes, five, 10, maybe 15 minutes after you're repeating that information, you're trying to learn that information. Again, this could be cognitive information or this could be a physical skill. Now, this really spits in the face of the way that most of us approach learning and memory. Most of us, if we use stimulants like caffeine or Alpha-GPC, we're taking those before or during an attempt to learn, not afterwards. These results point to the fact that it is after the learning and memory that you really want to get that big increase in epinephrine and the related molecules that will tamp down memory. So what this means is that if you are currently using caffeine or other compounds, and we'll talk about what those are and safety issues and so forth in a moment, if you're using those compounds in order to enhance learning and memory by taking them before or during a learning episode, well, then I encourage you to try and take them either late in the learning episode or immediately after the learning episode. Now, given everything I've told you up until now, why would I say late in the learning episode or immediately after? Well, when you ingest something by drinking it or you take it in capsule form, there's a period of time before that gets absorbed into the body and different substances such as caffeine, Alpha-GPC, et cetera, are absorbed in, from the gut and into the bloodstream and reach the brain and trigger these effects in the brain and body at different rates. So it's not instantaneous. Some have effects within minutes, others within, you know, tens of minutes and so on. It's really going to depend on the pharmacology of those things and it's also going to depend on whether or not you have food in your gut, what else you happen to have circulating in your bloodstream, et cetera. But at a very basic level, we can confidently say that there are not one, not dozens, but as I mentioned before, hundreds of studies in animals and in humans that point to the fact that triggering the increase of adrenaline late in learning or immediately after learning is going to be most beneficial if your goal is to retain that information for some period of time and to reduce the number of repetitions required in order to learn that information.

16. 1:00:50 – 1:04:48

    Tool: Enhancing Learning & Memory - Sleep, Non-Sleep Deep Rest (NSDR)

    1. AHAndrew Huberman1:00:50

       Now, I want to acknowledge that on previous episodes of this podcast and in appearing on other podcasts, I've talked a lot about things like non-sleep deep rest and naps and sleep as vital to the learning process.And I want to emphasize that none of that information has changed. Right? I don't look at any of that information differently as the consequence of what I'm talking about today. It is still true that the strengthening of connections in the brain, the literal neuroplasticity, the changing of the circuits occurs during deep sleep and non-sleep deep rest. And it is also true, and I've mentioned these results earlier, that two papers were published in Cell Reports, Cell Reports journal, excellent journal, over the last few years showing that brief naps of about 20 to up to 90 minutes some per- in some period of time after l- an attempt to learn can enhance the rate of learning and memory. However, those bouts of sleep, the deep sleep that night I should say, or those brief naps, or even the so-called NSDR as we call it, non-sleep deep rest, that was used to enhance the learning and memory of particular pieces of information, either cognitive or physical information or both, that still can be performed. But it can be performed some hours later, even an hour later. It can be performed two hours later or four hours later. Remember, it's in these naps and in deep sleep that the actual reconfiguration of the neural circuits occurs, the strengthening of those neural circuits occurs. It is not the case that you need to finish a bout of learning and drop immediately into a nap or sleep. Some people might do that. But if you're really trying to optimize and enhance and improve your memory, the data from McGaugh and Cahill and many other laboratories that stemmed out from their initial work really point to the fact that the ideal protocol would be focus on the thing you're trying to learn very intensely. There are also some other things like error rates, etc. Please see our episodes on learning. We have a newsletter on how to learn better. You can access that at hubermanlab.com. It's a zero cost newsletter. You can grab that PDF. It lists out the things to do during the learning bout. Still try and get excellent sleep. Again, fundamentally important for mental health, physical health, and performance. And we can now extend from performance to saying including learning and memory. Nap if it doesn't interrupt your nighttime sleep. Naps of anywhere from 10 to 90 minutes or non-sleep deep rest protocols will enhance learning and memory. But we can now add to that, that spiking adrenaline, provided it can be done in a safe way, is going to reduce the number of repetitions required to learn. And that should be done at the very tail end or immediately after a learning bout. Which is compatible with all the other protocols that I mentioned. And the reason I'm revisiting the stuff about sleep and non-sleep deep rest is I think that some people got the impression that they need to do that immediately after learning. And today I'm saying to the contrary, immediately after learning you need to go into a heightened state of emotionality and alertness. Now, it's vitally important to point out that you do not need pharmacology. You don't need caffeine. You don't need Alpha-GPC. You don't need any pharmacologic substance to spike adrenaline unless that's something that you already are doing or that you can do safely, or that you know that you can do safely. And I always say and I'll say it again, I'm not a physician so I'm not prescribing anything. I'm a professor so I profess things. You need to do what's safe for you. So if you're somebody who's not used to drinking caffeine and you suddenly drink four espresso after trying to learn something, you are going to have a severe increase in alertness and probably even anxiety. If you're panic-attack prone, please don't start taking stimulants in order to learn things better. Please be safe. I don't just say that to protect me. I say that to protect you. And I should mention that if you're not accustomed to taking something, you always want to first check with your doctor, of course, but also move into that gradually, right? Stop- start with the lowest effective dose th- dose, the minimal

17. 1:04:48 – 1:08:42

    Tool: Enhancing Learning & Memory - Deliberate Cold Exposure, Adrenaline

    1. AHAndrew Huberman1:04:48

       effective dose. And sometimes the minimal effective dose is zero milligrams. It's nothing. Why do I say that? Well, we already talked about results where they put people's arms into an ice bath in order to evoke adrenaline release. You are welcome to do that if you want. In fact, that's a pretty low cost, um, zero pharmacology, at least exogenous pharmacology way to approach this whole thing. That's a way of evoking your own natural epinephrine and it turns out also dopamine release. You could take a cold shower. You could do an ice bath or get into a cold circulating bath. We've done several episodes on the utility of cold for health and performance. You can find those episodes at hubermanlab.com. Also the episode with my colleague at Stanford from the Biology Department, Dr. Craig Heller. Lots of protocols, in particular in the episode on cold for health and performance, that describe how best to use the cold shower or the ice bath or the circulating cold bath in order to evoke epinephrine and dopamine release. The point is that the time in which you would want to do those protocols is after, ideally immediately after your learning bout, meaning when you're sitting down to learn new information or after trying to learn some new physical skill. Now whether or not that's compatible with the other reasons you're doing cold ex- deliberate cold exposure and whether or not that's compatible with the other things you're doing, that depends on the contour of your lifestyle, your training, your academic goals, your learning goals, etc. But if your specific purpose is to enhance learning and memory, you want to spike adrenaline afterwards. And so what I'm telling you is you can do that with caffeine, you can do that with Alpha-GPC, you can do that with a combination of caffeine and Alpha-GPC if you can do that safely. Some of you I know are using other forms of pharmacology. I did a long episode all about ADHD. I have to just really declare my stance very clearly that I am not a fan. I am actually opposed to people using prescription drugs who are not prescribed those drugs, right, in order to enhance alertness. I think there's a big addictive potential there also. There's a potential to really disrupt one's own pharmacology around the dopaminergic system. Um, however, some of you I know are prescribed things like Ritalin, Adderall, uh...And Modafinil and things of that sort in order to increase alertness and focus. So for those of you that are prescribed those things from a, uh, you know, board certified physician, you're going to have to decide if you're going to take them before trying to learn or after trying to learn. You also have to take into consideration that some of those drugs are very long acting, some are shorter acting, and time that according to what you're trying to learn and when. So that's pharmacology, but as I've mentioned, there are the behavioral protocols. You can use cold, and cold is an excellent stimulus because first of all, it doesn't involve pharmacology. Second of all, you can generally access it at low to zero cost, especially the cold shower approach. And third, you can titrate it. You can start with warmer water. You can make it very, very cold if that's your thing and you're able to tolerate that safely. You can make it moderately cold. How cold should it be in order to evoke adrenaline release? Well, it should be uncomfortably cold, but cold enough that you feel like you really want to get out, but can stay in safely. That's going to evoke adrenaline release. If it quickens your breathing, if it makes you go wide eyed, that's increasing adrenaline release. In fact, those effects of going wide eyed and quickening of the breathing and the challenges in thinking clearly, those are the direct effects of adrenaline on your brain and body. And of course, there are other ways to increase adrenaline. You could go out for a hard run. You could do any number of things that would increase adrenaline in your body. Which things you choose is up to you, but from a very clear, solid grounding in research data, we can confidently say that spiking adrenaline after interacting with some material, physical or cognitive material that you're trying to learn is going to be the best time to spike that adrenaline.

18. 1:08:42 – 1:12:36

    Timing of Adrenaline Release & Memory Formation

    1. AHAndrew Huberman1:08:42

       Now, I realize that I'm being a bit redundant today, or perhaps a lot redundant in repeating over and over that the increase in epinephrine should occur either very late in an attempt to learn something, or immediately after an attempt to learn something. I also want to emphasize the general contour of pharmacologic effects and of behavioral tools to create adrenaline. What do I mean by that sentence? What I mean is that McGaugh and colleagues explored a huge number of different compounds and approaches, everything from the hand into the ice bath to injecting adrenaline, to caffeine, to drugs that block the effects of adrenaline and caffeine, drugs like Muscimol and picrotoxin. Please don't take those. These are drugs that reduce or enhance the amount of adrenaline, and the overall takeaway is that anything that increases adrenaline will increase learning and memory and will reduce the number of repetitions required to learn something, regardless of whether or not that something has an emotional intensity or not, provided that that spike in adrenaline occurs late in the learning or immediately after. And anything that reduces epinephrine and adrenaline will impair learning, and that's the key and novel piece of information that I'm adding now, which is if you're taking beta blockers, for instance, or if you're trying to learn something and it's not evoking much of an emotional response, and you're not using any pharmacology or other methods to enhance adrenaline release after learning that thing, well, you're not going to learn it very well. In fact, McGaugh and Cahill did beautiful experiments in humans looking at how much adrenaline is increased by varying the in- emotional intensity of different things that they were trying to get people to learn, or by changing the dosage of epinephrine, or by changing the amount of epinephrine blocker that they injected. Lots and lots of studies. The key thing to take away from those studies is that for some people, adrenaline was increased 600 to 700%, so six to sevenfold over baseline in the amount of circulating epinephrine or adrenaline. And keep in mind, sometimes that increase was due to the actual thing they were trying to learn being very emotional, positive or negative emotion. And sometimes it was because they were using a pharmacologic approach or the ice bath approach. I don't think they ever used a cold shower approach, but that would've been a very effective one, we can be sure. However, other people had a 0 to 10% increase, so a very small increase in epinephrine. What we can confidently say on the basis of all those data is that the more epinephrine released, the better that people remembered the material. Over and over again this was shown, whether or not it was for cognitive material, so learning a language, learning a passage of words, learning mathematics, or whether or not it was for physical learning. I want to emphasize something about physical learning, because I know a number of you are probably drinking a cup of coffee or having a cup of yerba mate or maybe even an energy drink and taking some Alpha-GPC or something before physical exercise. I'm not saying that's a bad thing to do or that you wouldn't want to do that, but that's really to increase alertness. It won't enhance learning, at least not as well as doing those things after the physical exercise. Now again, many of you, including myself, exercise for sake of the physical benefits of that exercise, so cardiovascular resistance training, but we're not really focused on learning and memory. So, I emphasize this just so it's immensely clear to everybody. If you want to use those approaches of increasing adrenaline prior to or during physical training or cognitive work for that matter, be my guest. I think that's perfectly fine, provided that's safe for you. It's only by moving it to late or after the learning that you're really shifting the role of that adrenaline increase to enhancing memory specifically.

19. 1:12:36 – 1:15:12

    Chronically High Adrenaline & Cortisol, Impact on Learning & Memory

    1. AHAndrew Huberman1:12:36

       And as a cautionary note, don't think that you can push this entire system to the extreme over and over again or chronically, as we say, and get away with it. In other words, you're not going to be able to take a Alpha-GPC and a double espresso, do your focus bout of work, cognitive or physical work, and then spike adrenaline again afterwards and remember that stuff even better, right? I'm not encouraging, in fact, I'm discouraging you from-Chronically increasing adrenaline both during and after a given bout of work, if the goal is to learn. Why do I say that? Well, work from McGaugh and Cahill and others has shown that it's not the absolute amount of adrenaline that you release in your brain and body that matters for enhancing memory, it's the amount of adrenaline that you release relative to the amount of adrenaline that was in your system just prior, in particular in the hour or two prior. So again, it's the delta, as we say, it's the difference. So if you're going to chronically increase adrenaline, you're not going to learn as well. The real key is to have adrenaline mo-modestly low, perhaps even just as much as you need in order to be able to focus on something, pay attention to it, and then spike it afterwards. This is immensely important because while much of what we're talking about is actually a form of inducing a neuro-chemical acute stress, meaning a brief and rapid onset of stress. Well, chronic stress, the chronic elevation of epinephrine and cortisol is actually detrimental to learning, and there's an entire category of literature, mainly from the work of the great, and sadly the late, uh, Bruce McEwen from the Rockefeller University and some of his scientific offspring, like the great Robert Sapolsky, showing that chronic stress, chronic elevation of epinephrine actually inhibits learning and memory and also can inhibit immune system function. Whereas acute, right? Sharp increases in adrenaline and cortisol actually can enhance learning and indeed can enhance the immune system. So if you really want to leverage this information, you might consider getting your brain and body into a very calm and yet alert state, so a high attentional state that will allow you to focus on what it is that you're trying to learn. We know focus is vital for encoding information and for triggering neuroplasticity, but remaining calm throughout that time, and then afterwards spiking adrenaline and allowing adrenaline to have these incredible effects on reducing the number of repetitions required to learn. So if you're

20. 1:15:12 – 1:17:25

    Adrenaline Linked with Learning: Not a New Principle

    1. AHAndrew Huberman1:15:12

       like me, you're learning about this information, this beautiful work of McGaugh and Cahill and others and thinking, "Wow, I should perhaps consider spiking my adrenaline in one form or another at the tail end or immediately following an attempt to learn something." And yet we are not the first to have this conversation nor were McGaugh and Cahill or any other researchers that I've discussed today the first to start using this technique. In fact, there is a beautiful review that was published just this year, May of 2022 in the journal Neuron, Cell Press journal, excellent journal, called Mechanisms of Memory Under Stress, and I just want to read to you the first opening paragraph of this review which is, as the name suggests all about memory and stress. So here I'm reading and I quote, "In medieval times communities threw young children in the river when they wanted them to remember important events. They believed that throwing a child in the water after witnessing historic proceedings would leave a lifelong memory for the events in the child." Believe it or not, this is true. This is a practice that somehow people arrived at, I don't know if they were aware of what adrenaline was, probably not, but somehow in medieval times it was understood that spiking adrenaline or creating a robust emotional experience after an experience that one hoped a child would learn would encourage the child's nervous system, and they didn't even know what a nervous system was, but would encourage the brain and body of that child to remember those particular events. Very counterintuitive if you ask me. I would have thought that the kid would remember only being thrown into the river. My guess is that they remembered that but that they, the idea here anyway is that they also remember the things that preceded being thrown into the river. So both interesting and amusing and somewhat, um, I should say thought stimulating really that this is a practice that has been going on for many hundreds of years and we are not the first to start thinking about using cold water as an adrenaline stimulus nor are we the first to start thinking about using cold water induced adrenaline as a way to enhance learning and memory. This has been happening since medieval times.

21. 1:17:25 – 1:22:20

    Amygdala, Adrenaline & Memory Formation, Generalization of Memories

    1. AHAndrew Huberman1:17:25

       So up until now I've been talking about the pretty broad contour of these experiments. I've been talking about the underlying pharmacology, the role of epinephrine and so forth. I haven't really talked a lot about the underlying neural mechanisms. So I'm just going to take a minute or two and describe those for you because they are informative. We all have a brain structure called the amygdala. A lot of people think it's associated with fear but it's actually associated with threat detection and more generally, and I should say more specifically, with detecting what sorts of events in the environment are novel and are linked to particular emotional states, both positive emotional states and negative emotional states. So the neurons in the amygdala are exquisitely good at figuring out, right, they don't have their own mind but at detecting correlations between sensory events in the environment that trigger the release of adrenaline and what's going on in the brain. And because the amygdala's so extensively interconnected with other areas of the brain, it basically connects to everything and everything connects back to it, the amygdala is in a position to strengthen particular connections in the brain very easily provided certain conditions are met, and those conditions are the ones we've been talking about up into now, up until now. Emotional saliency that results in increases in epinephrine and cortisol or circulating epinephrine and cortisol being much higher than it was 10 minutes or 15 minutes before. And the net effect of the amygdala in this context is to take whatever patterns of neural activity preceded that increase in adrenaline and corticosterone and strengthen those synapses that were involved in that neural activity. So the amygdala doesn't have knowledge, it's not a thinking area, it's a correlation detector and it's correlating neuro-chemical states of the brain and body with different patterns of electrical activity in the brain. This is important because-It really emphasizes the fact that both negative and positive emotional states and the different but somewhat overlapping chemical states that they create are the conditions, as we say, the AND gates through which memory is laid down. AND gates will be familiar to those of you who have done a bit of computer programming. An AND gate is simply a condition in which you need one thing and another to happen in order for a third thing to happen. So you need epinephrine elevated and you need robust activity in a particular brain circuit if in fact that brain circuit is going to be strengthened. It's not sufficient to have one or the other, you need both. Hence, the name AND gate. And the amygdala is very good at establishing these AND gate contingencies. It's also a very generic brain structure in the sense that it doesn't really care what sorts of sensory events are involved provided they're correlated in time with that increase in adrenaline and corticosterone. This has a wonderful side and a kind of dark side. The dark side is that PTSD and traumas of various kinds often involve a increase in adrenaline because whatever it was that caused the PTSD was indeed very stressful, caused these big increases in these chemicals, and because the amygdala is rather general in its functions, right? It's not tuned or designed in any kind of way to be specifically active in response to particular types of sensory events or perceptions. Well, then what it means is that we can start to become afraid of entire city blocks where one bad thing happened in a particular room of a particular building in a city block. We can become fearful of any place that contains a lot of people if something bad happened to us in a place that contained a lot of people. The amygdala is not so much of a splitter as we say in science. We talk about lumpers and splitters. Lumpers are kind of generaliza- generalizers, if that's even a word. And I think it is, someone will tell me one way or the other, and splitters are people that are ultra precise and specific and nuanced about every little detail. The amygdala is more of a lumper than a splitter when it comes to sensory events. Other areas of the brain only become active under very, very specific conditions and only those conditions. And similarly, epinephrine is just a molecule, it's just a chemical that's circulating in our brain and body. There's no epinephrine specifically for a cold shower that is distinct from the epinephrine associated with a bad event, which is distinct from the epinephrine associated with a really exciting event that makes you really alert. Epinephrine is just a molecule, it's generic. And so these systems have a lot of overlap and that can explain in large part why when good things happen in particular locations and in the part- company of particular people, we often generalize to large categories of people, places, and things. And when negative things happen in particular circumstances, we often generalize about people, places, and things associated with that

22. 1:22:20 – 1:27:00

    Tool: Cardiovascular Exercise & Neurogenesis

    1. AHAndrew Huberman1:22:20

       negative event. So now I'd like to talk about other tools that you can leverage that have been shown in quality peer-reviewed studies to enhance learning and memory, and perhaps one of the most potent of those tools is

Episode duration: 2:09:16