A lot of our perception of space and time depends on our perspective as an observer. Memory is this incredible resource. It can be something that we can draw upon to be better people. It can be something we can draw upon to elicit more happiness, or something that can help us when we're uncertain. There is enormous power in the past if you can be flawed, flexible enough to get it.

Hey guys, how you doing? Hope you're having a good week so far. My name is Doctor Ronganchataji and this is my podcast, feel better live more we often think about our memories as a record of the past, but what if they're only a selective and evolving version of it? Well, today's guest is a world leading memory expert who has a surprising message. We're not supposed to remember everything. In fact, our brains are designed to forget and much of what you experience today will be lost by tomorrow. Doctor Charan Ranganath is a professor of psychology and neuroscience and director of the Dynamic Memory Lab at the University of California at Davis. For more than 25 years, he has studied the mechanisms in the brain that allow us to remember past events using brain imaging techniques, computational modeling, and research on patients with memory disorders. The occasion for his appearance on my podcast is the publication of his wonderful new book, why we remember the science of Memory and how it shapes us, which challenges, educates and enlightens on so much of what we thought to be true about memories. In our fascinating conversation, he explains that the seemingly selective and unreliable nature of human memory doesnt reveal laziness, distraction or early dementia.

Instead, it shows that our brains have not evolved to keep a comprehensive record of events rather than live in the past. The brains job is to extract the information it needs to guide our futures. We also discuss how memories create our sense of self. We learn that our memory is an unreliable narrator, but that we can use this to our advantage. By changing our perspective on traumatic experiences, we can feel differently about them in the present, a theory on which many forms of therapy are based on. We also discuss our brains ability to change its plasticity and how we are most likely to remember lifes emotional experiences as well as its new and surprising ones. Charon explains why music and smells are evocative cues, why its never too late to learn new skills, and why forgetting is a sign of an efficient brain. In fact, one of Charents key insights is that we shouldn't strive to remember more, but to remember better. This really is a fascinating conversation, full of fresh ideas, wisdom and practical advice about a topic that deeply matters to all of us. I wanted to start off with a quote from.

From your book.

Okay.

Memory is the prism through which we see ourselves, others, and the world. What does that mean?

Well, what it means is that I think we have an understanding of who we are. We have an understanding of the world around us, and we have an understanding of other people and all of that understanding, the connective tissue around the way in which we understand the world and ourselves and others is memory. Basically, we interpret the actions of others and their goals through our own memories of how people have treated us and our own memories of how we have behaved and our understanding of ourselves. Even though you might think yourself as being a very static entity, the self really develops over time. And somebody with a memory disorder, what you find is they end up frozen in time, and their personality does not develop that much relative to the time that they had brain damage. And so that's a interesting contrast to how the typical brain works over time.

One of the reasons I really like that quote and why I've enjoyed reading your book so much, is because one of the central cases you make is that who we are today, how we act today, in many ways, is influenced by the past, by the memories that we've kept from the past. And I was thinking about that through the lens of, let's say, dementia or age related cognitive decline. Many people around the world, they are either experiencing this or they know parents or family members or loved ones who are experiencing that. And so let's say it's a mother or a father who is now forgetting things compared to when they were younger. For some people, that's really, really difficult, like for their kids, it can be really difficult to interact with them. And it makes me think that there's a much broader philosophical point for me, which is, who are we without our memories?

Yeah, there is a sense of who you are without memory, but it's a very impoverished sense. I think, to some extent, if you reflect on who you are, you have to go back to who you were, who you have been, what you've done. Although what's fascinating is that you look back on the past through the lens of beliefs that you have about who you are. And so often we draw on an incomplete past in order to construct our sense of who we are. But at the same time, you still are drawing on those memories. And I think early in the stages of dementia, what you see in the MCI stage of Alzheimer's, for instance, which is very, very early, people do have a very crisp sense of who they are. But as the disease progresses into its more insidious forms. People lose a lot of that sense of who they are. Interestingly, in some cases, it can actually, they can be more peaceful, because sometimes I think people actually, their memories allow them to get stuck in loops of rumination and worry about the future. And so to some extent, somebody who has a memory problem can be happier because they are in the present.

But on the other hand, what happens, of course, is for those of us around somebody who's suffering from dementia, it could be just extraordinarily disturbing. My own grandfather had was brilliant filmmaker, and he actually did the first technicolor films in Telugu and I think maybe Kannada and a few other languages. Oh, wow. Yeah. So he was a brilliant, brilliant man. Wrote and directed films and was composed and sing and. But, yeah, he was. He had vascular dementia and died far too young. But. So I saw this, and it really is touching when you. I mean, in a hard way, to see someone lose that knowledge of everyone around them.

What's the evolutionary case for memory? I mean, why do we remember anything at all?

Well, this is the whole point of I wrote the book, in fact, is that essentially, if you think about it from the perspective of evolution, the past is the past. It's over with. So if we survive the past, why should we carry it with us? But the case to be made is that memories give us leverage to understand the present and the future. Right? Memories allow us to say, hey, I was in this cave and I got attacked by a bear. I better not go back there. But memories also give us a sense of like, hey, I tried this orange thing and I peeled it and I ate it and it was very tasty. Let me go back and get some more nutrients from this orange thing. That's kind of a memory. There's memory of. I thought this fellow cave person was my ally. I now realize they're my enemy. So we often have to stop and stop on a dime, sometimes mentally and flip. Based on our recent experiences, based on what I call episodic memory in the book, which is just drawing on one event. And this is very different, I think, than how.

Let's say, for instance, in AI, you have this kind of slow plotting generalization from just lots and lots of data. A human can take one instance and just draw from that and change the way they understand the present and change the way they anticipate what can happen in the future.

Many of us, I think, when we think about memory, we think about how can we improve our memory? How can we get it better? And of course, I want to cover that with you. But there's also cases in the book where memory gets in the way. You've kind of touched on that already in the sense of negative past experiences or let's say trauma, traumatic events that we can't let go of in those instances. It's not that we're looking for more memory, are we? We're actually looking to down regulate the memory that's been stored. I mean, how do you look at that?

Yeah, memory for. It's very interesting because having worked when I did my clinical training, about half my time was spent testing people who were worried about memory loss. And then the other half was working in the clinic with people who were processing their traumatic memories that they couldn't let go of. And I would argue we don't want to let go of the memories of the traumas that we've experienced, but we want to be able to experience in a way that's tolerable and manageable and limited. I think the problem that happens when traumatic memories take a life of their own is that it just really has this negative impact on us in a day to day format. But one of the things I talk about in the book is this idea that our memories of what happened are very different than the stories we make up about it and the physical emotions that we experience in the moment of remembering. And that can be useful in terms of treatment and growth.

That part of the book, chapter five, was one of my favorites, actually, and I reread it a number of times because maybe because it had personal resonance for me. But I think many of us think that when we store a memory from the past, good or bad, that we store the emotions with that memory, that it's one entity. That event happened. It was a negative event that I felt sad and fearful and anxious about. So when I recall that event, I also see those emotions as well. I also feel those emotions. But in that chapter you wrote, the brain mechanisms for remembering what happened are different from the brain mechanisms responsible for the feelings. Now, first of all, is that true? And secondly, why is it important for us to know that they're stored almost in different places?

So when people remember an emotional experience, what happens is that you do get the content of what happened, but you also feel it, sometimes viscerally, right? Like, so if you've been in a car accident, for instance, remembering it can probably bring your heart rate up and give you. Your eyes might dilate a little bit. And that feeling of remembering is what people associate with a vivid memory. So we've done studies where we give people memories for just random images, but they could be an image of a car crash, for instance, or an image of that's more pleasant of a person holding a baby, let's say. And what you find is that people will report remembering the car crash pictures more vividly. But interestingly, they don't necessarily remember the details of that car crash picture any better than the baby picture. So, in other words, and when we look at the brain activity, what we find is that there's an area of the brain called the hippocampus that's important for pulling up all these details from this past memory, linking it all to that context. But the amygdala is another brain area, which you probably talked about, I imagine, on your show, as being very important for emotional responses of many kinds, not just fear, but also positive emotions and reward attachments, so forth.

And that circuit is what drives the more physiological response that we have to remembering. That's at the root of many of our emotions. Now, when we experience it, it's often all together, especially because the amygdala and the hippocampus work together, but they're different in the sense that you can look at people who have memory problems and they still feel the emotions of past experiences, and you can actually look at people who have amygdala damage who don't feel it, but they remember it. And when we look at brain activity, the brain activity in the amygdala is more correlated with the emotional experience and the sense of vividness, but the hippocampal activity is more correlated with the actual memory for the details.

So how is that helpful, then, if someone is, let's say, suffering with PTSD, post traumatic stress disorder? And you do talk a little bit about this in the book. Right. How is it useful, then, to know that these are stored in different places? Does that have a therapeutic benefit?

I believe so, and I believe so for a number of reasons. So, first of all, cognitive behavior therapy has two different components. So, one is behavior therapy and the other is cognitive therapy. And behavior therapy is literally all about sort of reprogramming these more physiological aspects of emotional memory processing, meaning that it's like, just by sheer repetition over and over, the brain can learn to basically overwrite that fear response or that sense of threat that you have when you remember, say, something very traumatic, like an abuse experience or an assault or a combat. And then the second part of it, though, is the cognitive element. And I think, and this speaks to other issues that we can get into for sure, which is that we often remember these experiences in ways that are deeply rooted with our interpretation of what happened. Right. So if you feel the sense of this visceral sense of fear, and you recall many instances of the event that occurred, you can then put this all together in a very negative story and one that's very harmful, but it's possible. And many people do have experiences from the past that are very negative, but they learn from it in some ways.

Sometimes they learn not to make mistakes that they did before. Sometimes they learn that they're resilient and that they have this capability to overcome these things. And I think that's the cognitive piece, is reframing the interpretation that you have around this experience. And so that gets into this principle that memories have this interpretive, almost imaginative component. But also these memories can be revised and updated. And we do this all the time, in fact.

Yeah, this is such an interesting point. I think if you ask most people what they think a memory is, I think a lot of them would say, well, yeah, something happened in the past, and I have a memory of that incident. I have an accurate memory. I have an accurate recollection of that incident. But actually, one of the big things I've learned from your book is that a memory involves imagination, but also every time we revisit a memory, we're almost updating it and subtly changing it.

Yes.

Is that accurate?

I think that's very accurate. I love it. In fact, I should take you on the road with me. We'll be a great team. No, I mean, that's absolutely the right way of thinking about it. I don't like to talk about in my field, sometimes we talk about false memories and we talk about amemory, but really, memory is much more flexible and dynamic than that. And so I say memory is much more like a painting than a photograph. And what I mean by that is, if I'm trying to paint a picture of the scene now, and supposing I was a competent artist, I would probably capture some aspects of the scene very accurately, maybe your eye color, maybe your facial expressions and so forth. And I could certainly make errors in my picture that I might draw. But then on top of it, I would have some interpretive issues that are really reflecting my perspective as I look at you or my beliefs. And those are used to fill in the blanks to provide this connective tissue. And that's how memory, I believe, works, is that we have some elements of truth to our experiences, and then we have some errors sometimes that are details that are wrong.

But then also, we have an interpretation that's not necessarily true or false. It's just our interpretation. And so. And that's based on our perspective and the way we look at the world. But what's interesting is we can go back and revisit events from different perspectives. We don't have to see it exactly the same way. And, in fact, I would argue we routinely do. I talk in the book about one case where I had a near death experience, and over time, it just became a hilarious story that I love to share with people. So I think we. In fact, my saying in life is there's no use in having a horrible experience unless you get a great story out of it.

Okay, so let's take that, because that. I think maybe that illustrates this point really well. Right, so you had a near death experience so that could be stored in your body as something negative and fearful, are you saying? Basically by re updating it and tweaking it, sharing a different perspective, looking at it under a different light, however you want to describe it, you have now converted a fearful experience into a funny one.

I do this all the time, and I'm sure many of your listeners do, too. In fact, obviously, there are certain kinds of traumas that are very hard to make light of. So I do not want to tell people, oh, yeah, just laugh it off and you'll be great. But I do think we do this all the time. And, in fact, just the act of sharing a memory can change it. And what I mean by this is if I'm telling you a story about something that happened to me, I'm shaping it into a narrative. But this narrative is no longer something that just sits around and regurgitates in my head. It's a narrative that's designed to communicate something to you. And that changes my perspective right off the bat. So now you tell me your perspective in real time, and you bounce these ideas off, and now I'm changing it. I'm rotating my frame of reference, and I'm looking literally through a new lens at these same experiences. And sometimes that can lead you to real growth. I think that's the special sauce in therapy, is this idea of seeing things from a very different point of view.

Because often the memories that people are most traumatized by are ones that are associated with shame and guilt, and they're things that they very rarely talk about. And those are the experiences, I think, that people need to exchange the most. Not because just indulging in a traumatic memory will make it better. I'm not of the belief that just simply wallowing in a negative memory will somehow cure you or that you'll just get some catharsis and everything's going to be okay, but through the process of having someone else look at it, who's empathetic and their goal is shared with you to make progress, to look at things a new way and find growth. Because every experience has some different way that can be looked at.

It's really powerful that not just for severe trauma, for all kinds of experiences that we initially perceive as negative, and those words are quite key, initially perceive our perception as negative. I mean, one incident for me, and this relates to therapy. So I've done a form of therapy called ifs, internal family systems. So, in one of those sessions that I was doing with a therapist, we revisited an incident from when I was about eight years old, right? So, in my house when I was eight years old, and by revisiting it as my. I think at the time, my 40 year old self, I was able to put a new story on that same incident. So the incident happened. Eight year old Rongan developed a certain interpretation of that, which then led to me having certain behaviors and reactions throughout my life. But it was absolutely profound, because by going into that incident, updating it, changing the narrative, I found almost instantaneously within days, like, my behavior was different. Now, some people say that Ifs is one of the types of therapy that go to the root cause and deal with it right there and then.

I'm not asking necessarily to speak to that, but more about this idea that you can go in and change your memory. And then I was also thinking, well, why is it that then changes my behavior? Is it because when we sleep, you know, things start to change with our memory. So if I've given it a different story in the daytime, well, when I go to sleep, is my brain then updating that memory? I think it's called reconsolidation or something like that. So is there any truth to what I've just said? Do you see it like that, having studied memory for decades now?

So you can just start off by just the actual therapy experience you have. Right. And if you look at some of the work in emotion regulation, my friend Ethan Cross wrote this book called Chatter, which is about the stories that we tell ourselves in our head. And one of the things he talks about in terms of the negative stories, the ruminations that we have, which are all about rumination, is always about memory. It's really thinking about things that you regret or things that other people did to you and traumas and stuff, is to really look at it from a third person perspective, look at it from an outside perspective. And the perspective issue is quite powerful, because there's basic, basic studies showing that you can give people, let's say, even just a boring story. But this one experiment I just love to talk about over and over again is like, people hear a story about these kids walking around in this house, and they're playing hooky from school. And in one case, you're asked to. To watch this from the perspective of an, I believe it was an estate agent. And the other, or it was either that or prospective homebuyer.

One of the two, my memory is imperfect, and the other one was the perspective of a thief. And what you find is, naturally, the one who's looking from the perspective of a thief. They recall all the valuables in the house. And the other is, if you look at it from the perspective of the home buyer, the estate agent, you remember all the things that determine the value of the house. But then what they did was they flipped people's perspective and they said, okay, now change it. If you were thinking about this as a thief, think about it as a home buyer. And people recall all of these parts of the memory that they couldn't access before just by changing their perspective. So now you brought up this idea of sleep, and let's go to that. Sleep has a bunch of effects on memory that we're still trying to figure out. It's quite complex. One idea is consolidation, which is that you strengthen individual memories. Uh, but there's another compelling line of evidence, which I quite like, which is that, uh, and we found some evidence for this in my own lab, which is that, uh, sleep allows the brain to find connections between different experiences that we've had.

Right. So this ability to find connections means that you can now take an experience that you've had right now and say, hey, wait a minute. One week ago, I had an episodic memory that links up with this. And a month ago, we had some information that connects to this. And so it can start to build some wisdom and knowledge out of what's happened. It can also allow you to incorporate information that's inconsistent with your beliefs, inconsistent with what you used to think, and that allows you to be more flexible and change and grow exactly along the lines that you're talking about. So I believe sleep can play this very powerful role, and I think it's. We don't know nearly enough about these things, but I think it's very important that in post traumatic stress disorder, sleep is profoundly affected, and you have these night terrors are part of it. And I think what happens may be that the traumatic memory takes hold and is just constantly being reprocessed. So you mentioned the term reconsolidation. And so this is a phenomenon that's been studied extensively in non human animals. And the idea is that if. If I'm afraid of driving and I repeatedly drive over and over and over again, what can happen is that the brain learns to basically suppress the fear response that you have to driving.

It learns in this particular context, I'm safe to drive. Then it learns in that particular context, I'm safe to drive. And so gradually, you can overcome that fear by sort of saying, here's a safe zone. Here's a safe zone. But reconsolidation, the idea is that when I retrieve a memory, like a fear memory, I can actually open that memory up to changing it. And it works by sort of partially activating the memory. So you just give a little spark, and then the memory pops up, but then it's opening up to change. And we don't know a whole lot about when and how that works in the human brain. Sleep might play a role, but I'm actually thinking that some of the new psychedelic psychotherapies, like MDMA for post traumatic stress disorder, it may be a mechanism that you retrieve these memories. You view them from a profoundly altered perspective, one in which you can be more dispassionate or maybe compassionate, I don't know. And revise these memories because psychedelics can enhance plasticity in the brain.

I mean, something you just said, maybe think about comfort zones and the benefits of within reason going outside our comfort zones, right? So, for example, I don't know. You could take anything in life where you feel a bit fearful, let's say public speaking, right? So let's say the first time you have to get up and speak in front of 500 people, for whatever reason, you might feel afraid, right? Your amygdala might become rampant and sort of overtake the rational part of your brain, the prefrontal cortex, and you may not do a good performance because you're so nervous. Is this accurate based on what you just said, that if you do that, of course not everyone will be the same. But let's say someone does that 20 times. The first time they're really scared. The second time they're like, oh, actually, it wasn't that bad. The first time they were a little bit better, but they're still, like 90% scared compared to 100% the first time. And by the 20th time, they have learned that actually, this is okay. No one's gonna laugh at me or throw their phone at me or their pen or whatever it might be.

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So technically, it's probably more extinction. The difference between extinction and reconsolidation, I apologize if the viewers feel like we're going into the weeds here.

This is great. I love it.

Okay, so basically, if you go back to, like, Pavlov and the oldest studies of learning. So extinction, the idea there is that basically, um, you're learning something new. So reconsolidation, the idea is you're erasing some part of a memory. You're actually erasing the fear.

So in the example I gave from an incident from my childhood, reconsolidation, is me erasing the fear from that negative situation earlier on in life. Is that. Is that true?

It could be. Or it could be that you're reframing it in a way that reduces the cycle of fear that you have when you remember. Just as an aside, talking about memory, one of the fascinating things about writing this book that I really love is that people feel compelled to tell me their memories. And it's just I've heard so many poignant memories from so many people, positive and negative. It's just astounding. So it's been a real gift to have the chance to interact with people about memory. I can imagine distinction is basically the brain learning. This is a safe environment. It's like you habituate, you get kind of get like. We used to do this with panic disorder. People who have panic attacks in various locations is you'd actually have people hyperventilate, and so you'd have them breathe into a paper bag very rapidly until they hyperventilate. And it wasn't because we were, like, trying to be sadistic. It's because basically people would get into the state of panicking, and then that response eventually goes away and you learn, hey, I can have this. The brain is basically tweaking itself to say, I made a mistake in this environment.

I've done this, and I didn't have a heart attack. Everything's okay. And through just plowing through this experience over and over, the brain starts to suppress that fear response. So it's a new form of learning. Now, technically, reconsolidation is more of an erasure of the original fear association in the first place. And we still don't know how well it can be harnessed in the clinic, because this is like, it's most effectively studied in animals, where you give them these intense drugs that sort of, like, wipe out plasticity at the time of retrieval. But I do think whether or not you call it reconsolidation, or whether or not you call it extinction, or whether or not you call it memory updating, we have an enormous degree of flexibility in the way that we feel about our memories. And I think that can happen through just raw trial and error over and over again. I mean, I know for a fact that, like, my fear of getting on the highway when I drive has gone down since my first times when I was driving. I've been around long enough now that I've seen people when I was early in my career, some professors whose research really got hot, and you'd watch them give talks, and it was like watching just like an accident in slow motion.

It's just miserable. I'm feeling this gut wrenching fear just watching them, like they could have collapsed at any moment. And then I see them give their hundredth invited talk, and they're just fine. And I've seen this myself with teaching. I mean, this has been one of the things about teaching that's great is you are thrown into baptism of fire, and students can smell. They're like sharks sometimes. They can really just sense the blood in the water if you're scared. And you just have to plow through that until, like, by the end of the quarter, you're just a different person.

Yeah. Fascinating, this idea that we update a memory every time we go and revisit it. I think it's really powerful. I think many of us have experienced the situation where maybe with a friend, you were both at the same event, the same concert, the same night out, whatever it might be, but you remember it differently. And I think there's something really compassionate behind the idea that we update our memories, because a lot of the time, people argue over a different recollection. No, that's not what happened. This is what happened. But actually reading your book makes you think more and more, well, hold on a minute. Maybe both perspectives are true. People are just seeing a different angle of the same event. But, of course, sometimes people remember different, you know, the same experience differently. But I don't know. It was quite a compassionate view. It makes me think, well, you know, in terms of what is the truth?

Yeah.

It's like, well, there are multiple truths on any event.

Yeah, yeah, yeah. Oh, exactly. I mean, I use the quote in the book from Ben Kenobi that many of the truths that we cling to depend on our own perspective, which is one of my favorite lines from Star wars, where Luke Skywalker is like, you lied to me, and he's like, many of the truths that we cling to depend on our own perspective. And it's so true because we literally have a very limited perception of reality. Even in the moment, I might feel like I'm seeing this entire room. But, in fact, you could have all sorts of. You could. If we lived in some magical world where the books were literally changing in the background, I would not notice, because I'm not literally seeing it in the moment. I'm constructing this picture of the world that's based on my beliefs and based on my memories. And likewise, you can do these people have done these studies of people who are in two political parties who watch the same debate, and they walk away with completely different recollections of that debate because they're pulling out the instances from that debate based on their beliefs. There's studies of, like, football fans who watch the same match.

It's like a championship game, and one team wins and one team loses, but one team is one the fan of the winning team is remembering all these great plays, and the fan of losing team is remembering the times that the opponents cheated and the referees made the wrong call and all these other bits that are based on their belief and.

That even, I think, applies to disagreements within relationships. I often use this example, but I really like it because two romantic partners having a disagreement, stroke argument. What really happened? It kind of depends who you ask. Everyone's been in that situation, I think, where within the couple, two people have got a different recollection of the same event. And it doesn't necessarily mean that anyone's wrong. It's just they're remembering different things.

Yes. One of the you can extend this even further. You get into a fight with your spouse, you're thinking not only of what just happened that caused the fight and remembering all these things that they did to make you angry, but then you're also remembering all the other things that they've done in the recent past to make you angry. And that makes you feel even angrier. So then you eventually make up. A week goes by, and not only can you not remember all those things that they did to make you angry, but you can't even remember what you fought about. So you are literally seeing the past from a different perspective as you were at the moment of that fight. Right. So I think we underestimate even our own flexibility and the dynamic way in which, if I'm feeling excited and positive and optimistic, I have a very different lens through which I'm viewing the past than I do if I'm feeling miserable and feeling depressed or if I'm feeling angry. And so, really, a lot of our view of the past is so intensely colored by the present.

Yeah. One of the things that's had a profound impact on the quality of my life and how content and peaceful I feel these days is choosing to adopt the belief that if I was that other person, I'd be doing exactly the same as them now. Why I think that's really relevant to memory and the things that we're talking about is this idea that we can change our perception. Right. With enough repetition, I believe we can change how we view people and the world around us. And so my default reaction with almost anything and anyone now is, if I were them, I'd be doing the same thing. So what is it in their life, in their upbringing, in their recent past, that has led to them thinking about the world in the way that they currently think about it? You can talk about this in politics or negative comments on social media or, you know, interactions within a family. Why does that person think the way that they think? And I think it, for me at least, that speaks to this key concept in your book, which is memories are not fixed, right? So maybe I'm not talking about memory.

I'm talking about in the present, how I interact with the situation. But I guess the point I'm trying to make is that just as you can update your memory and tweak it, you can also update and change the way you view the world and the people around you. You don't have to be a victim to your past. And the way you used to think about the world when you were ten or 15 or even when you were 25. You have agency because of neuroplasticity, because the fact that the brain can change, you can also change the way you view the world, right?

Oh, absolutely. Absolutely. This is a fundamental part of the book, is, I mean, I really do believe this, that we all have this capacity to change, no matter how old we are. It can be very difficult that once we get into these, dig ourselves into these ruts, it can be very difficult to get out of them. But, you know, I would encourage people to think about, if you see yourself as somebody who is, you know, generally makes good decisions. And like you said about this thing with empathy, I think this is, there's an actually quite a literature on this of what's called the empathy gap, where if we fail to think about what others are doing and why they're doing it, we can also fail to think about what we would do in that situation, in that moment. So, for instance, I think many of us has had these moments where we're like, you know, you're extremely scared and defensive and will behave a certain way. But if you're not feeling scared right now, if you don't have a visceral sense of immediacy, it's probably hard to imagine how you would feel. And people do these things where they'll, you know, they'll say, oh, I had this bad breakup.

I'm never going to talk to this person again. And then they see this person again, and they just overcome with desire, and they make the same mistake over again that they did before. And so I really do think we. We often fail to appreciate what we could do in the moment. There's. And there's enormous positive things you can do with this. If you're preparing for a job interview, thinking about times where you've been successful can really help you feel better in the moment. Um, also thinking about, if you're trying to be more compassionate, thinking about times where you've been altruistic can make you feel more altruistic in the moment and make you more likely to engage in altruistic behavior. So there's enormous power in the past, if you can be flexible enough to get it.

That makes me think about the power of reflective practices. Right. So if the starting premise is that the way we view the past is changeable, that we can change our memories, and that we do change our memories, whether we want to or not, then you know what? I talk a lot about self reflective practices, like journaling. Or maybe once a week on a Sunday when you're having a quieter day, you can reflect on your week, what went well that week.

These are the good things.

These are what I learned. How does that play into memory? If we're actively reflecting on the positives, let's say even gratitude practices, a lot of science mind gratitude practices that is effectively going. I'm not to going to be held hostage by humans negativity bias that exists for a very good reason. I'm going to proactively take charge again. No, I'm choosing to remember the good stuff, what I'm grateful for, and therefore I'm going to start seeing more things in everyday life than I'm grateful for. How does your research around memory play into these kind of self reflective practices?

Well, it's funny you mentioned this, because after writing the book, I've started to say, well, how can I actually incorporate many of these things in my own life? Quite lousy at doing so, I'll just be quite honest. But one of the things that I've started to do is when I have a moment to really reflect. The book tour hasn't been great for that. When I have a moment to reflect, I try to do a gratitude practice. And I used to feel like, oh, I'm terrible at gratitude, which is a very negative belief. And then I decided one day to try something a little different. Rather than saying, trying to focus on the big things in life that I'm thankful for, to just take very small things that happened during the day. It could be an email that I got from a friend. It could be like something nice someone said to me in a hallway, but just these little random episodic memories. And I found that it would have a snowball effect. Thinking about the most mundane, positive thing that I had in the day made it easier to access other positive things. And initially, it was a lot of work sometimes because I can get tired at the end of the day and feel quite negative.

But then I would pick up a little thing, then that make it easier to pick up another thing. And then next thing, you know, I had access. It's like it just opens these doors to all of these different memories. And the memories, you know, I didn't have to work to feel thankful, because the memories did the job for me.

Yeah. Why do we remember certain events more than others?

Well, our brains are, first of all, just designed to take in a small amount of information we know from, you know, over a century of memory research that basically the overwhelming majority of the details of the things we experience are going to be gone. So thinking about what determines the fate of a memory is very important, right? There's a number of factors. So one is literally importance. And what I mean by this is what is biologically important. So the experiences that are associated with emotions like fear or desire or love, these are biologically important events that are associated with those experiences, right?

For survival.

For survival, right. Attachment is very important for survival. Obtaining rewards, avoiding threats, these are all very important. Anxiety, even, is important. Right. It's like, if you're worried that a predator is going to come out at any second, you do want to have an increase in stress hormones that will allow you to mobilize very quickly. And maybe you don't want to have too much planning and reflection going on. You want to be reactive rather than, you know, think too much about things that could happen, but really be aware of threats and mobilize. And so these are things, as I said, they're biologically important. And if you look at, um, the major chemicals in the brain that are associated with these states, things like dopamine, noradrenaline, serotonin, I'm sure you've talked about some of these chemicals on your show. These are stress hormones, like leukocorticoids, uh, like, uh, cortisol, for instance. These are chemicals that promote plasticity.

What does plasticity mean?

Well, so a memory itself, we think, is driven by a change in the connections between neurons. So neurons are the basic individual cells in the brain that are the most granular computational unit. Right. But a particular conscious experience we have isn't driven by a single neuron, but a whole collection or assembly of neurons that are active at a time. But to remember that event, you need to access some subset of those neurons that were active during the original event. So there's a bit of a re experience, so to speak, of the original event. And we never get everything, and we never get the whole unfolding in time, but we get little bits and pieces and fragments. And the reason we're able to do that is there's a change in the connections between the neurons, the synapses, so to speak. And that's what we call synaptic plasticity. Now, for listeners who don't care about these terms, what this comes down to is literally the brain is reshaping itself. The structure is literally changing such that if I activate some of the neurons that were active during a past experience, if I can just get in there and.

And activates some of them, you get this chain reaction where other neurons in that network also come alive. And so, as a result, that memory can pop up again. But it truly depends on these changes in the connections between neurons. But those connections can be quite labile, and they can undo themselves. And so what happens is, when these neuromodulators are released, like dopamine or serotonin or noradrenaline, they actually stabilize the changes that happen. They stabilize the plasticity so that the connections can be more long lasting. And as a result, the memory can be more long lasting. You can retain it for longer.

So, basically, events that have happened in our life that, through an evolutionary lens, would have been very important for survival, we are absolutely going to remember it, that those neurochemicals are going to be released. That's going to help solidify those memories in our brain. So we're going to remember when we nearly got mugged, when we were walking home when we were 17, from a bar or whatever it might be, right? We're going to remember that. And instead of looking at that as a negative thing, that kind of makes sense, doesn't it? We want to remember that.

Absolutely. And it's not just the negative or even the positive things. It's also the things that are surprising or the things that are novel and brand new. Like, you know, my first time going into your house, my first time exploring this region of England, you know, this is like my. I feel more alive. It's a little, you know, and that feeling of being more alive is like it's. It can be unpleasant for people sometimes to experience things that are new and surprising, but that's your brain basically saying, hey, let's do something with this experience, because this is going to be important for me to carry with me in the future.

There's a nice bit in the book where you talk about neuromodulators, and my recollection is that this idea that during these intense events, let's say a stressful event, we're flooded with these neuromodulators, which change the way we remember things you wrote, they influence how and what we remember, but also that the effects of something, for example, like noradrenaline, lasts for hours afterwards. After something has been emotionally intense, it doesn't just come on and off during that event. It lasts for a long time after. And I think you're making the case that that helps us remember these events in a different way from a much more neutral event.

Yeah, I think the time course is a little controversial as to whether it will last hours after the emotional event, but the memory will last for hours.

What sort of event are we talking about? You know, is it like an extreme event where you were held up at gunpoint or you were, I don't know, you were at a red light in your car and someone was really upset, and they start to get out of their car and come towards your car? I mean, that is a situation that many people have experienced before.

Right.

It's quite common. Yeah, it's not uncommon, I should say. So maybe through that lens, talk us through what happens. What are these hormones that come and what's the point of them?

Yeah. So these chemicals, some of them would be considered neurotransmitters, some of them would be hormones. Even things like estrogen, testosterone can affect plasticity. But you can take, let's say, something like a stress hormones, stress hormones, glucocorticoids. And these have a very slow time course. And what's interesting is when you're in a phase of stress, let's say you're. You're getting into a fight, let's say, with somebody who you really care about. And so this fight's happening. Now. What's interesting is, is that these chemicals can enhance plasticity not only for the things that are happening during the fight, but also a little bit before and a little bit after, the effects can spill over in time to events that preceded and followed the experience that elicited the stress in the first place. And again, biologically, this is what you want. If you go back into the proverbial cave that I mentioned before, or you get attacked by a bear, you not only want to remember that you got attacked by a bear, but you want to remember all the circumstances that led up to being attacked by the bear and what followed that, because that's all valuable information.

So there can be this broader time course of the things that surrounded the event. But I think one thing we can also appreciate is that it's not a matter of stronger or weaker. I think in neuroscience, sometimes they try to reduce it to a strong memory and weak memory. But actually, emotions can change the. They can color the perception of the experience and the memory of the experience. So that I will particularly remember the things that are most emotionally significant. I'll particularly remember the parts of the memory that are associated with the threat, like the fact that the person pointed a knife at me, but not necessarily the color of their socks.

Yeah. There's a much bigger idea, isn't there, that in any interaction, any situation in life, there are multiple things that are always going on, but we don't remember them all. We remember the things that are necessary to remember, probably, or most commonly, for our survival. Right. So if it was a really worrying, stressful incident, I find this fascinating, that the noradrenaline that gets released also helps us lay down a memory, not just of what happened, but what preceded it happening. And let's say if that much noradrenaline wasn't released, we'd remember the event, but we wouldn't remember the steps that happened just before it. And that, of course, makes evolutionary sense. It makes something of something you said earlier on, where I think it was the kids playing hooky from school, and depending on the lens through which you looked at it, you would remember different things. Right. So the broader point for me is that we're constantly being exposed to all kinds of inputs, but we can only consciously remember the inputs that we decided were important to remember. But what happens then, if that is true, right. What happens then? I think you mentioned if, from a thief's perspective, they're looking at the house and they're seeing all the valuable things.

Right? So that's in their memory. But then you ask the same person to imagine they're an estate agent and they remember different things. So I guess, for me, does that mean that we are storing all of the things that happened, or a lot of them, and depending on the perspective we take, that opens up, like, certain neural pathways so we can remember certain things that are relevant to that perspective. Does that make sense?

That totally makes sense. Does totally make sense.

But that is wild. Yeah, because that means there are, then, for want of a better term, hidden memories. Like, there are memories that our brain is not bringing to our consciousness because it doesn't feel it's relevant in that moment.

Well, I might call it dormant or latent. And the reason I say that is because, and this is one of the fascinating things about memory, is people often think of, again, memories as strong or weak, but we often have these memories that we don't even know are there. And then you hear a song from your childhood. You smell something, or you're in a place that you haven't been to in years, and it just pops into your head. And what that shows is that sometimes you can have a memory that's capable of being strong. It's there, it's dormant, but without the right cue, you can't access it. It's like this locked door, and you need the key to get in. And mental context, the feelings we have, the places that we're in, the smells that we're experiencing, or the sounds we're hearing can create this window, or this can give you the key, so to speak, to unlocking those memories that you wouldn't have normally even known existed.

You mentioned music, and, of course, I think many of us have experienced that moment where we hear a song that we haven't heard in ages from a particular time in our life, and we can start to feel those feelings. It could be a loved one's death, it could be a breakup. It could be freshest week at university, whatever it might be. But that music can unlock things that you couldn't consciously think about or bring to your awareness. And, you know, why is that? I mean, do we know from the science and your research, like, why that might be?

There's a few reasons. So one, I think, is that we've touched on this already is that music tends to evoke emotional responses from us. And these emotional responses can be then very formative for memory. But there's another part of it, which is music tends to be part of what's called a context. So, in the hippocampus, basically, it's forming memories not based on your knowledge of the world or anything like that. It's just saying this whole experience that we're having, this experience that we're sharing right now is happening at a particular place at a particular time. And so I have all these areas of the brain that are basically processing what you're doing, processing the sights and sounds around me. But then the hippocampus is creating this big picture of how it all comes together, and that's what we would call the context. The context can include the emotions, but also the smells, sights, and sound. And music is a very powerful contextual factor. It's like the sound. I know that you're very into music, and for me, it's a deeply personal thing, and it's the soundtrack for our lives. And there are particular songs that we listen to during particular phases in our lives.

And so again, if it's unique. So a key to memory is distinctiveness. If there's a cue that's uniquely associated with a particular time in your life, it can be a vehicle for mental time travel, it can be a vehicle to take you back to other things. Because memory is all about cues and context. And so if there's something that brings you back to that past context and activates that mindset, then that mindset now is a cue to pull up more information. And what happens is you can get these chain reactions where you mentally go back to one time and you recall one thing. Recalling one thing now cues up another memory. And so you can. It can have the snowball effect where now you feel like you're back in that time and place.

We're seeing that with certain studies. I think if patients with dementia and in certain homes, I've read research showing that if they play music from that individual's youth or from their twenties or from their thirties, you almost evoke different behaviors, different facial expressions, like things that people couldn't access before without that music. I mean, that is pretty incredible. First of all, are you familiar with that research? And secondly, I don't know. When you hear things like this, I just think it makes us, or it should make us more humble. I go, how much? How much is our brain picking up that we just have no idea. Do you know what I mean? It's like we just don't know what is being stored inside us. But then the odd thing, but a musical, maybe a smell, maybe is a candle sense that can do the same thing, right?

Absolutely. Or being in a particular place. Like, I did my sabbatical in Cambridge, actually, and on Sunday I had a day of breaks from a book tour and I went to Cambridge to visit my old friends there. And just seeing certain landmarks brought me back. It wasn't just a memory of something that happened, it was the feeling of being back in the past. And it's just remarkable when this happens. Places are very powerful part of that, too. And if we want to go backwards to a previous topic, fear and stress can have this effect where it not only helps you remember the things that evoked that fear response or whatever, but also the stuff that happened before and after. And people have found this with other factors, too, like novelty. So Richard Morris from Edinburgh, actually, so your alma mater, he did these famous studies where he basically would have a ratio, learn the locations of food, but he would find that in this particular experiment, it was very forgettable. And the rat would soon forget where these food locations were. But if he put the animal in a new box that he'd never been to before, and if you're a lab rat, being put into a new box is a very stimulating experience.

Right. Kind of like how I might be if I got to go somewhere new after a long week of tedious work in the office. And so what happened is that that would actually rescue the otherwise forgettable memories for the things that happened right before. And so. And that was associated with dopamine, which again, is thought to be this neurotransmitter that's associated with reward. But it's really just about surprise, novelty and energizing you to get either information or get rewards. I know it's a little bit of a non sequitur going back, but I was also just very interested because we've been talking a lot about trauma, but there's also very positive elements of memory that can be enhanced. And this goes with music too.

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So one of the things that you see with a lot of neuromodulators is it's not necessarily a more is better thing. We used to see this in our stress studies, where you get what's called an inverted U response. So if you imagine the letter U and you put it upside down as a graph, right. The left side of it would be, if you have low levels of stress hormones, for instance, it can actually be bad for memory. If you have medium levels, it can be very high for memory. But once you get too high, you kind of get over the edge. And actually it's bad for memory again. So I wouldn't necessarily say with dopamine. I mean, I don't know for a fact that more is better. But in general, increasing dopamine activity can enhance plasticity. And certainly the kinds of experiences that you can get in a day to day thing, like just being in a new place, doing something new, trying out a new activity, meeting new people, can give you a little bit of that response. And that's why I really encourage that for people who are older. I think as we get older, we tend to get more set in our ways, and we could be a bit more rigid.

But it's really this beautiful, easy way to kind of take advantage of the brain's natural plasticity is to go out and seek novelty.

Yeah. Plasticity in that setting, when you say, when there's high dopamine there, it's a new experience. It's novel. How is plasticity helpful in that situation? Why should someone hear that and go, yeah, okay, novel experiences are going to increase dopamine, which is going to increase plasticity. Why is that important for that individual?

Well, I think we all complain about our memory, and we are often trying to improve memory. And so just in that sense, harnessing that plasticity can be a good thing just by incorporating a little novelty into our day. But I also think that there's something to be said for allowing ourselves to incorporate new information into what we believe and what we experience. And this is something that's kind of a latent theme throughout my book, is, I think we tend to view memory as something that should be effortless, and that if you're remembering easily, that's like, that's the ideal. But in fact, you learn more when there's a little bit of discomfort, when there's a little bit of struggle. Something I think you briefly mentioned at the beginning of our conversation, that this act of being in a new place or being around people who are different from us can be unpleasant in a slight way, in the sense of it's new and our brains, you can feel it struggling a little bit to adapt, but that is an enormous opportunity to broaden your knowledge, to give you more grist for the mill and imagination, for instance, in creativity.

And if you look at people who are extraordinarily creative artists and creative musicians, they are constantly seeking novelty and trying to incorporate that ability to find connections between things that shouldn't otherwise go together.

Yeah, I really love that section, actually, the book about creativity and what really drives it and how memory plays into that. And it reminded me of, I would imagine you've had this experience as well when you're writing. I've just handed in last week the latest, hopefully the final version of my manuscript for my next book.

Hey, high five.

Yeah, for sure.

Doesn't feel.

And, you know, over the last few months, as I've been really trying to finish it off, I felt I needed novelty. I wanted to travel, I wanted to go to different towns, different cafes, like walks in different areas. And it really did help. I mean, look, I'm telling myself a story. It helped. But I honestly, having been here before with previous books, I really find that actually is, as you're sort of suggesting, it's like you unlock a different part of your brain that you can't access when you're in the same rhythm and routine every day. Does that make plausible biological and neuroscientific sense?

Yeah. Yeah. Because one of the things that many, many researchers have shown is that the brain is constantly tweaking itself. And you can see this in every part of the brain that's been studied, to my knowledge, is that if you repeatedly do something in a very predictable way, the brain tweaks itself to optimize, to do that thing very well. And so when you have large deviations, things that are unpredictable or points where things are very novel, there has to be a large shift and a large reconfiguration in networks in the brain to accommodate this new experience. And, in fact, there's a school of thought that that's what the brain is trying to do, is take the most informative information, the stuff that violates our predictions, stuff that doesn't fit with what we already knew, and prioritize that for new learning. So rather than trying to learn everything, the brain is focusing on what's most essential, because if you already know a lot, you only have to encode the information that doesn't correspond to what's happening at the moment. And so if you engage in a very predictable set of actions, what happens is that you don't really form rich memories so well.

And you can see this, for instance, many of us in the lockdowns, in the pandemic, we just had this very repetitive, predictable set of experiences every day because we were just stuck at home, you know? And what that, what that meant was that for a lot of us, we don't have much memories of it other than just kind of the global trauma of the lockdowns. I don't think we, many of us have very rich memories from that time period. It's almost like this collective amnesia, which, which is in and of itself kind of scary.

Does that speak to this concept called event boundaries that you write about?

Yes. In fact, that was the example where event boundaries came into play for me so much in my own experience. So the concept of event boundaries is related to the fact that our episodic memories are related to context, right. So the place that happened, the kinds of goals we had and so forth. So even though our life is very continuous, right after I leave here, you'll go on to some other activity, you'll go on to some other activity, and it's all one continuum in time and space, when we remember these things, we tend to remember in a more discreet way. We tend to remember, here was the time in which we were having this conversation. And once you step out that door, your mindset will change to something completely different. You'll be on to a new goal, a new task, and you'll feel like you're in a different place. And what happens is, we found in our studies of brain activity is that when people are engaging in a very predictable event, for instance, the brain really encodes memories at these moments where you transition from one event to another, which are the points that are most surprising sometimes or most new, or just a shift.

Right? And that's those shifts are what we call event boundaries. Now, one of the interesting things is you can see this when people just even change a room, because suddenly what happens is your mindset changes as you go from one room to another, which is why we sometimes end up in the kitchen and you say, well, why am I here again? And so if we went to the kitchen right now to, let's say, get something, we showed up at the kitchen, we might be like, saying, oh, wait, why did we go in here again? Then we might say, oh, while we're here, why don't we get a few biscuits and come back? And then we come back into this room and, ah, we remember we were supposed to get your phone or something, right? So that's because of event boundaries. Because what happens is, is that when you change your mindset, your mental context shifts, and now it's harder to remember the things that happened in past context. Now, the problem with the lockdowns is we were staying in the same place, doing the same things, talking to the same people all day and all night.

And so as a result, you didn't have these big event boundaries, you didn't have these big context shifts. And so rather than having a very distinctive set of memories, you just had one big blur, one blob of experience. Yeah.

It's so fascinating because so many people, myself included, will catch up with someone you haven't seen since 2019, for example. Right? And we're recording this in 2024. So it's technically five years ago, but it only feels like. Yeah, only saw you about a year ago. It's like, no, wait a minute, it was five years ago. That's because of event boundaries. Right? That's because depending on which country you were in and what the restrictions were. But, you know, for the best part of two or maybe three years, the way you lived was very different. And was quite monotonous. So instead of it being a three year period, I guess maybe your brain has almost perceive that as like a three month period. Is that kind of what's happening?

Well, our sense of time in and of itself and the passage of time is very strongly related to our mental context and the changes in mental context. So for instance, if I'm like, it's almost like space, right? So if something is like 100ft away, for instance, versus 110ft away, those things will actually look very close together. But if something is 10ft away versus 20ft away, those will actually look very far apart. So a lot of our perception of space and time depends on our perspective as an observer, right?

Yeah.

So if we get back to this idea of context as being a crucial part of time, what can happen is, is that more context changes can lead to more of a perception of the passage of time. So event boundaries can have a very warping effect on our sense of the passage of time. And so just as an example, if when I was in lockdown, I was experiencing this and we had to do these polls when we're teaching classes just to keep students engaged. And so just for the heck of it, I said, do you feel like time is moving faster, slower or about the same over the course of a day? And almost every student said that time was moving more slowly over the course of a day. So then I would say, okay, if you look back at the past week, do you feel like the weeks are going by slower or faster? And they said, well, the weeks are going by very quickly. And I dont know if that was your experience, but it was certainly mine. But the math doesnt work out right. If the days are moving by more slowly, theoretically the weeks should too.

But what had happened was people had the sense of enormous monotony during the day. And so as a result, without that sense of event boundaries, time seemed to be moving at this glacial pace. But then at the end of a week, you look back and you say like, well, what happened over the past week? I don't even remember what happened. And so it felt like time was just slipping away and we're hemorrhaging time, you know? And so I guess the sense of what happens from five years ago, it's really slippery because it just depends on how much shifting was going on during that time.

Why is it easier to learn languages as a child than as an adult?

Because the brain is more plastic. So we've talked a lot about the hippocampus, but a lot of the higher level computations that happen in the brain are thought to happen in the neocortex. So if somebody thinks about just the prototypical picture of a brain. So if you just all mentally picture a brain, or if you have a picture in front of you, you'll see all this convoluted gray matter, right? And that little blob of wrinkly blob of gray matter is the neocortex. So all these areas we've, some of these areas we've been talking about, like the prefrontal cortex, that's part of the neocortex. Now, in the adult brain, those connections change quite slowly, meaning that the learning in the neocortex is somewhat gradual. But early in development, the connections between neurons in the neocortex can be quite labile. That is, you can get a pretty dramatic reconfiguration of connections in the neocortex. And so that allows us to really grab on to new things much more quickly because the connections between brain areas are just so labile.

And what does label mean?

Labile means that it's like they can be changed very quickly.

So it is true, like, kids pick up things quicker than adults?

Yes. Yes, definitely. And it's true with music, too. And actually, there's some interesting work. I wish, I'm slightly afraid to tell you this because I might not remember it accurately, but there's interesting work suggesting that children that learn a musical instrument from very young ages can actually develop perfect pitch or be more likely to develop perfect pitch as an adult, meaning that they can hear notes more effectively in music. And actually, their whole auditory system is tweaked for that purpose. So languages are like this, too. And so as an adult, we're fully capable. We have all the plasticity to learn a new language. I want to be clear about that. But as children, we can pick it up faster, and we're more likely to develop a native accent.

Well, that's interesting. More likely to develop a native accent. You see that, don't you, when people move countries in their twenties or their thirties, and they don't always take up the accent of their new country, let's say, compared to when they move as kids. So that's really, really interesting. In your book, you wrote that when you turned 50, you said you were going to write a book, which you've done, but secondly, that you were going to take up surfing. How's that going?

Terrible. Terrible. Davis where I live is not very close to the coast, so I haven't had a whole lot of practice. I did have a period right after I turned 50 where I was trying it, and it was touch and go where, like. But I did have times where I was able to stand up for people who haven't tried it. Surfing is an exceptionally brutal learning curve because you think it's just writing standing up, right? But that's part of it. And it's very hard, especially at the age of 50 when you're in poor shape like I am, but it's physically very demanding. You're using all these muscles you didn't know you have. But one of the fascinating skills in surfing is reading waves, which is also one of the beautiful parts of it. You sit on a surfboard and you look at the ocean and you see the waves coming, and you anticipate when is that moment where I start paddling like hell. And a skilled surfer will time. They'll put themselves in the right spatial position and they'll time it just right so that it just seems effortless. I didn't get very far in that because I need more time in surfable places.

So maybe the book will help me with this. Well, I guess the reason for me.

Asking that is relative to what we just said, which is it's easier to learn things when we're kids. I think your message is, yes, it may be harder for you to learn surfing in your fifties, but it's not impossible.

Oh, absolutely not. It's not at all impossible. And I really, really hope older people take this into account, because I think we often get frustrated by the obstacles in learning. But what's interesting is when we face those obstacles, that's when we're learning the most. As long as you have some kind of a feedback that's telling you this is how to do it, that feeling of struggle is when we're learning the most. And if you feel like something's effortless, you're probably not learning very much.

Not only that, I spoke to a neuroscientist, Doctor Tommy Wood, on this show. Well, several times, actually. But the last time he was on, we spoke about a paper that he published hypothesizing that one of the major causes of age related cognitive decline is the fact that we stopped learning new things and we stopped giving our brains that novel input, which, which you've already touched upon. Right. He is saying, like, you learned loads at school, you've constantly been exposed to new information, but then it kind of starts to stop. And if you do retire, let's say, at 60 or 65, and you stop learning new stuff, well, your brain has no reason to keep growing and the neuroplasticity and all those things. So I think there's another benefit there as well, right?

Yes. And we can think of it as the opposite, too. The more predictable of your daily experiences, the more your brain starts to over fit to that predictability and it becomes less open to things that are different. Right. So I was talking to somebody very recently who was doing some experiments where he was giving people movies to watch, and he had surprising endings on some of the movies. And people tended to have a bias to remember it as if the movies ended more predictably than they really did. And so I think there's something to be said for exposing yourself to novelty and exposing your brain to struggle, if nothing else, to develop more openness to things that violate the predictive nature of our daily lives.

Yeah. And I guess that speaks to people, let's say, who, I don't know, struggle in social settings. The more they become fearful, the more they stay at home and not go to the yoga class with other people, or not go to the cafe because they have to interact with the barista or other customers, whatever it might be, the harder it gets because your brain then down regulates. And so what you thought was tricky actually becomes trickier because you're avoiding it more.

Yeah, yeah. And there's all sorts of reasons why that can happen. I mean, one is just kind of the discomfort of new learning. As you get older, you might just not want it anymore. Uh, some of it might be also, uh, sensory problems. One of the things that we know is that, uh, hearing aids, actually, for people of hearing deficits can be very good for promoting, uh, um, uh, for stalling cognitive decline. And we don't know why. But my suspicion is, is that you have much less noise going on in the brain. You can use your attentional resources to focus on what's around you. You're going to be more confident and less, and that allows you to engage more with the world.

Let's talk about some of the common perceptions about memory. Memory is something that nobody wants to lose. Everyone hears these stories of age related cognitive decline, or sees parents, or in your case, your granddad's. And I think many of us, most of us think, I hope that doesn't happen to me. So what is normal as we get older? You mentioned before the situation where you end up in your kitchen and you forget why you went into the kitchen in the first place. Is that normal or is that a sign of dementia?

Oh, that's absolutely normal. And what it is, it's usually not a sign of dementia, because if you walk into the kitchen and you don't remember why you went there and you walk back to the room that you came from, you'll often go, oh, that's what I need. Right. So, it's not that you didn't have a memory for what you're supposed to do, but rather, you didn't have the memory accessible when you needed it. And that's exceptionally common as you get older. It's related to changes in prefrontal function. This area of the brain that we talked about that allows you to focus on what you need at a given moment. And so, as we lose that functioning, you're a little bit more reactive rather than proactive, and it's harder to shift your mental context or remember things.

So, is it a sign of age? Basically, I get that it's common. Let me put it this way. If we were doing what is necessary to look after our memory as well as we could, would that still be happening?

You have enormous abilities to reduce the changes that happen with age, in particular the frontal effects. And I think you. I'm sure you've talked about this with many of your listeners. Things like aerobic exercise, things like maintaining a healthy diet can reducing chronic stress and having ways of mitigating the chronic stress of everyday life. These can all be very important. One of the things that we found is that, uh, people, for instance, with cerebrovascular disease, like hypertension, that cause disturbance to, uh, the blood flow in the brain. They have changes in the white matter that really these. These are long range connections, kind of freeways in the brain. And so, as a result, the prefrontal cortex becomes disconnected from a lot of other areas, and you're less likely to activate it. You have more of these absentminded memory gaps that happen. Okay.

Right. This is really interesting. Let's go back to that kitchen situation. The reason I want to go back there is I just want to get or really understand this point clearly. You said that this is common. You said that many of us, and I think, I'm pretty sure that pretty much everyone listening to this right now has experienced this. At some point, they end up somewhere, and they can't quite remember why they were there in the first place. Now, you're saying it's not a sign of dementia, but you're hinting that it doesn't happen when we're younger. So, I guess what I'm really trying to understand is, are we accepting a degradation in our ability to remember because of the way we're living today. So should that happen when you're 30 or really, if things were more optimal, would we only start to get that situation where we turn up in a location and forget when we're 60 or 70?

Yeah, I would say that probably I was not being precise in the way I was talking about all this because, in fact, everybody forgets. Right? And so this, you can document these kinds of effects in young adults. I mean, some of these effects of event boundaries have been documented mainly in college students who are supposedly at their peak memory functioning. So it's definitely not the case that it's just something that happens with.

So it's not a problem.

It's not a problem. And, in fact, forgetting happens to everybody. We often have many, many memories that are just even in optimally functioning people, they should be forgetting most of what they experience.

That's a key point. Right. And that's one of the big points in your book as well, which is, you know, we don't remember everything. In fact, much of what happens today, I will forget.

And that's exactly what you want.

In fact, if the human brain was to remember every single thing that happened to us and in our lives every single day, it'd be overwhelming, wouldn't it?

Well, yeah. An analogy I give is like, I can look around in the studio and it's fairly neat and organized, right? But I could look at this and say, well, why aren't you a hoarder? Why don't you just throw as much stuff in as you can and never throw anything away and just fill the space? You've got all the space here that's not being used. Why not just hoard and hoard and hoard? And you'd say, well, that's ridiculous. Why would I want to do that? I want to be able to find what I want when I want it, right? And so there's a Marie Kondo approach, which would be to say, I'm going to let go of the things that don't matter and organize and hold on to these things that matter. And I think that's how the human brain is optimal when we basically hold onto the things that matter. And that's why I say in the book not to remember more, but to remember better. And so the problem with aging is not that we can't remember, but we often remember stuff that's inane at the expense of the things that are important.

And definitely what you're talking about in terms of modern life. Modern life often takes us away from what's important and gives us these more blurry, fragmented memories.

How much of a role is electronic media playing here?

So electronic media does not have to have bad effects on memory. And in fact, some studies can show that it can have good effect. But the way we interact with it and the habits we develop can, in fact, cause problems. And so, for instance, if you can see, you might see this, especially with your kids. There's been this proliferation of Instagram walls. So you go Instagram walls? Have you heard of this?

No. Go on.

Okay, so maybe this is more of a us thing, but definitely if you.

Go, maybe I'm out of touch with the kids.

Well, I can join you in that place. But basically these are like you go to a cafe or a restaurant, and they'll have a wall that has all this plants and stuff, flowers and things, and it has the name of this place in big letters. And so the idea is you go there and you take a picture of it and you immediately post it on social media. And I think this is kind of indicative of a way in which we interact with technology, that we just mindlessly document things, and we assume that because we're documenting it, we will remember the experience. But in fact, the way we're interacting with the world, through the lens of the camera or through the lens of our phone, so to speak, is changing the experience itself. That is, we're no longer there, but we're rather viewing it through the lens of just mindlessly taking pictures. So there's studies that show that if I go somewhere and I take pictures of it, I will feel that I'll be more likely to retain memories, but in fact, I could be less likely and I could go further and just say that it doesn't have to be that way.

You can use photos more selectively in ways that allow you to actually focus on the sites that are here, focus on the exact moments that you want to capture, and that can enhance your memory and give you better access to these events later on. But that's not usually how things happen. And I think like Snapchat, for instance, where your posts literally disappear after a couple of days, it's like a metaphor for how you remember in the modern world.

There's quite a modern phenomenon, which is people going to concerts and recording large amounts of that concert whilst looking through their phones. Now, look, my bias is I've got my own bias here. I grew up in an era where this didn't exist. I don't get it. I don't personally understand it. I also don't want to be judgmental of other people who choose to do it. And of course, lots of kids are growing up in an era where that is the normal thing to do. It almost doesn't exist if I didn't record it and post about it. Right? So let's take a concert, for example, where there's a band playing and a certain individual, let's say, is going to that it's a band that they really like. They're really. They're there, they're enjoying it, they're dancing with their friends, and they're also videoing a lot of it. So watching a lot of it through their screen. How does that impact the way they store that? So five years or ten years later, their ability to remember that concert, how does it change when you are doing it like that compared to when you're not?

It depends somewhat on how you do it. Right. So I think it's like the idea of documenting the concert is you want to remember what happened, but when we actually remember, we remember our experience of what happened. And our experience is not what's happening on the stage, but what's happening in our heads, what we are seeing and hearing and feeling. So part of. I mean, I don't know about you, but part of being at a concert is the place where it happens and the sense of interacting in this communal exchange with other people. And so if the camera is taking you away from that and getting you in your head about just how can I get as much of this concert as possible? You're depriving yourself of the memory of what that experience was, which I would argue is much more valuable than the actual live performance itself.

What if you took a photo when you were there? What if that individual took a photo of them and their friends with big smiles on their faces? Right? So they're not recording the music, which I would argue never sounds as good when you replay it afterwards compared to when you're actually there in the arena. But just trying to speak to the concepts in your book, if you're documenting the emotions and the people you were there with, would you think that that might be better? Because then when you're looking back, you're remembering, oh, God, I was with these really good friends of mine, and we caught up and we were smiling, we were laughing. Is it different the way we store memories if we do it like that?

Yes. Because what's happening is you're orienting yourself. You're actually planting cues in memory no matter what you're doing. Memories is all about planting cues, right? So what's the cue going to be? Is the cue going to be something that's happening on stage, or is the cue going to be the experience of being with your friends? And so that photo is a potential cue, a pathway to an experience.

Like you said before, when you hear music, you're unlocking a memory that was always there, but you can't access without the key.

That's right. That's exactly right. And so, and if you're documenting just what's going on on stage, it can potentially give you more memory for seeing what was on stage. But without a picture or two of you really hanging out with your mates and enjoying it, you won't necessarily have access to that part of the memory.

What if you went in to the concert with no phone and no camera? Right? So you're not being distracted by the phone and the camera and the emails and the Instagram or whatever else might be on your phone, which is, of course, very common for most of us these days. But you're literally just there now. Of course, you could be mindless whilst you're there, but in theory, with all your decades of memory research, do you think that not having anything with you to capture the experience means that your brain captures it in a much deeper way?

I believe so. I believe that if you're not mentally there, you're not even having the experience. So there's nothing really to remember other than taking the picture, other than taking the video. And conversely, if you are mentally there, you will have a memory of the experience. But I would also say that pictures have a very valuable. There's a lot of potential in pictures, and one is if you document selectively and you go back to the pictures, you revisit them. That act of recalling the memory, as we've talked about, can change the memory, but it can also strengthen the memory. So sometimes that change can just make it stronger. So you and I probably remember as kids having photo albums, and we would actually look back at our photos. And I don't know about you, but for me, I rarely look at my photos now, but if you're very selective, you have a better chance of being able to revisit those photos and then use them as triggers for memory retrieval. You talked about journaling. That's another way to do it, too. But these forms of documentation, to the extent that they're reminders, they allow us a window, again into that past.

And the more we go back, the more we're able to solidify that memory.

Okay, here's a real life scenario. Today's Thursday. On Monday of next week, I'm going to see John Mayer in London. Right. Haven't seen. Haven't seen John play live for a few years. He's one of my favorite artists.

He's a great guitarist.

For me, he's got everything. Guitar playing, songwriting, voice, lyrics, everything.

Like, good looking, too.

I think he's. I think he's incredible. He's still one of the artists who I would still travel to go and see. So I'm going to London next Monday to watch him. So if I want that experience to be lodged in my brain and for me to remember it, how might I go about that evening to increase my chances that that's going to be the case?

That's a really good question. I mean, part of it, I would say, would be to really engage with the place, engage with the emotions, engage with the. And what I. It's. It's hard for me to describe it, but it's like, often, I think, for people who are very intellectual, we get stuck in our heads. And the problem is, is that a memory for a thought is not all that different from something that you just imagined. Right. So if you're going all the way to London to see this concert, you're probably paying a lot of money to get tickets for this concert.

Yeah.

And you want to get the most of it. You have to be there. And part of being there is the sights and the sounds and not necessarily the. And the feelings that are happening in that moment that are evoked by being there, being with whatever friends or family you're going with, being the food that you're eating, the sights and the sounds that you have. And so it's really important to get out of your head. I'd probably also say, don't get plastered, which often happens in concerts or, you know, well, let's.

Let's talk about alcohol and what it does to memory, because, of course, alcohol is something that many people consume. What happens when we experience something and alcohol is present in terms of our ability to remember it?

Alcohol has a number of effects on memory, but let's. The most important one is it blocks plasticity. And so as a result, what happens is people who consume too much alcohol. For instance, you can get blackouts where you don't remember the entire time that you were drunk, because what happens is you're blocking the changes and the connections that you need between neurons to allow you to reactivate those memories. Even if you don't get blackout drunk, we often have blurry memories for these experiences. It's. And again, the plasticity is part of it. Part of it is it's shutting down your prefrontal cortex. And so you're kind of just grabbing memories of whatever it is around you. But it's very blurry memories. And then part of it, which is really fascinating, is it's part of the context. So the episodic memory, a big part of it is the feeling of being drunk, if that makes any sense. There's a very particular mindset that you're in after a couple of beers that you're not in when you don't have those couple of years. And so there's actually some studies that suggest, and I say this with the, I want people to be very clear about what I'm saying and what I'm not saying.

But there are studies that show that if you have an experience when you're slightly tipsy, you'll find it easier to remember that experience later on when you're in a tipsy state. Again, now, I'm not saying now the best memory will be if you don't get tipsy, and then you're completely sober when you try to remember later. But if you do have this experience when you're tipsy, one of the odd things that happens is recalling that memory will be easier if you're in a slightly tipsy state.

Again, it's the same principle, though, isn't it, where you said music can unlock memories that you can't access without the music, or it's harder to access. It's that context around an event that's so important. And I guess if you were somewhere where you were tipsy, it kind of makes sense that you almost can't be there and remember it when you're sober. But if you're the same level of tipsiness, your state is different and you can then remember. It's. Yeah, it's super interesting, isn't it?

Yeah. Yeah. And emotions are like this, too. Emotional states we're able to, when we're feeling angry, you can remember things that happen when you're angry, when you're happy. You can remember things that happen when you're happy. So all these physical sensations. There's even a great study by this psychologist, Alan Baddeley, who showed that divers who memorized words while they were underwater found it easier to recall those words when they were underwater. I mean, it's just the context can be so rich and multidimensional. It's the sites, the sounds, the smells, the emotions, the thoughts, the physical states. It's all there.

I'm interested as to where we store memory in the body. You just mentioned that sometimes we can get stuck in our heads, and we don't pay attention to the smell, the sound, the ambience, whatever it might be, in a particular situation. But what about this idea that emotions and memories perhaps can be stored in the body? So many body workers, massage therapists, therapists of all kind, will often tell you that when a certain part of the body which was tight, let's say, gets released, people can start crying. They can start to remember stuff at a different part of their life. I've had that experience myself, actually, to do with my psoas muscle. And so I guess that's emotions rather than memory. I'm just wondering, from your perspective, is there anything in your work that might explain that or speak to that?

Well, I've heard from a number of people that they've read things about how trauma is stored in the body, and I think that I can't speak to every part of this, but I do think that people neglect the idea that the brain is a body part. The mind is a product of the brain. And so when people tell me that trauma is stored in the body, well, I say, well, the brain's a body part, and so it is. But that's not necessarily surprising. And so these memories of painful experiences, for instance, are stored, in my opinion, in the brain. And. But the brain is interacting with the body throughout. I mean, there's all sorts of, you know, so hormones that are driving our physical responses in the body are also modulating memories. You can see even waves of activity in the brain that parallel people's breathing cycles. And you probably talked about heart rate variability is something. And there's a whole fascinating line of work on this topic and relating it to cognition. So I guess I would encourage people not to get caught up in the idea that necessarily memories are locked in the body, but more into this idea that the brain and other body parts, it's all connected in this way.

So that our brains are registering part of the context of an event is our internal context, our bodily context. We are embodied.

We are embodied. The other way I think about it sometimes is that sometimes we have adopted a posture or certain patterns in our body that mean we can't access certain thoughts. And when that part of the body is released, like, our posture can change and we become different people, we can access different parts of our brain because it's all connected. So actually, in some ways, we could argue that, but it's a little bit reductionist to say trauma is either stored in the body or the brain or the mind or whatever it might be, because actually, these things aren't separate. They're all constantly interacting. So whatever viewpoint you take there, I don't think you need to take many leaps to go. Yeah, it's totally believable that you could release a part of the body and generate a really deep, visceral emotional reaction.

Yeah, yeah. I mean, you've had one, right? So you know this, that you can get the emotional reaction, and that doesn't necessarily mean that a memory for a trauma is stored there, perhaps, but that when you manipulate the body, it has effects on your mind, and that can have effects on memory. So it's, as we've been talking about, it's all connected. Right. And so many things that affect your physical states can affect your mental context, which can open you up to memories that might not normally be accessible.

Often, Ciara and I talk about these four pillars of health, food, movement, sleep, and relaxation. Okay, you briefly touched on them, but let's just go through each of them and think about how making changes in that area can affect our memory. So you mentioned food, a good quality diet. And, I mean, that's another topic in and of itself, what that means. But generally speaking, a good quality diet can help our memory.

Yes. And one of the things that we're still learning about is the gut microbiome. So we know that the gut microbiome is interacting with the brain. And there's a fascinating study that I saw, and it's one of those things that you just hear about a study, and it just blows your mind. And so I was at this conference talking to somebody who studies nutrition effects on the brain, and he was telling me about the study where, like, these rats were given this high sugar, the equivalent of a rat, equivalent of a can of Coca Cola a day. And what they found was, when they became adults, these rats had memory problems and changes in the hippocampus relative to a rat that was eating healthy, rat, shower, whatever. But the trick was they took the gut microbiome from the coca cola rat and put it in a rat that was having a healthy diet, and they developed memory problems and had changes in their brain structure, too. So this is just, it's so relevant to this idea of how things are connected because things like stress, for instance, interact with that gut microbiome. Illness can interact with the gut microbiome.

Is that frustrating sometimes as a scientist, where you have to isolate and reduce things down to study them? Does it sometimes get frustrated when you think, yeah, I've studied this one thing in this one part of the body, but then, oh, my God, everything's connected. So that matters. But this and this. And this also matters.

It really is one of these things that gives you some humility, because, you know, there's a long. Just as an example, there's so much work out there on the neuroscience of addiction. And kind of tracking the pathways in the brain that are related to addiction. But I saw a really compelling article fairly recently from a neuroscientist who had been working in this area for a long time. And he came to the conclusion that a lot of this research was presenting this misleading picture of addiction as a disease of the brain, reflecting brain damage or weird brain function, as opposed to part of the social context that people are in, which is affecting the brain and poverty and challenges of prejudice, for instance, and all these factors that are being basically filtered into the brain. And so, again, it is very hard to translate any of these little things into the big things that happen in the real world. It's challenging. That doesn't mean that there's no relevance, but it does mean that we need to think more holistically about the brain.

I think I heard you in one interview or one presentation you gave say that there is some research that blueberries can have an impact on memory. Is that right?

There is some research on blueberries and as antioxidants that can have some positive effects on maintaining cognitive health in age. There's some new data on multivitamins, for instance. So there are these indicators. What I would say, though, is to focus more on the big picture. So, for instance, being able to maintain cardiac health is just huge for memory and maintaining cognition.

What does that mean, cardiac health?

Well, things like avoiding hypertension, also not cardiac per se, but diabetes, for instance. Managing diabetes or never going there in the first place, as you know it dramatically increases your risk for Alzheimer's and so forth. So maintaining, like, blood sugar levels that are. That are healthy. Cardiac health, like avoiding hypertension, avoiding cerebrovascular disease, cholesterol, keeping cholesterol down. And so these are big picture effects that are part of a. Related to a holistic diet things. And so I think sometimes people want, oh, can I take ginkgo? And that'll help me remember. And I think that's that kind of an easy solution. There will probably be some statistical benefit for some of these things, but that doesn't mean that everybody who takes a particular supplement will benefit. Some probably will get worse.

Yeah, I completely agree. And I think one of the dangers of focusing on, let's say, blueberries is that that people could conclude, well, you know what? I'll just keep going with my junk food diet. As long as I have a punnett of blueberries a day.

Exactly.

I'm going to be okay. It's like, well, I don't know which research paper we're referring to here, but I think you're going to get more benefit from actually cutting the blueberries and having just a more generally healthy diet seven days a week than thinking that it's going to mitigate other poor food choices, for example.

Yes. Yeah, yeah. That's exactly right. That's exactly right.

You mentioned aerobic exercise and its positive effect on the brain and memory. Why is that? Do we know some of the mechanisms? Is it just blood flow and oxygenation, or is it more complex than that?

It's many things. It is more complex than that. Although blood flow and oxygenation is a big one. This speaks to the everything is connected principle, which is why some of these lifestyle changes that you make can be just so powerful. So let's talk about the blood flow part of it. For instance, your brain depends on being able to process energy as quickly as possible, and that requires good blood flow. And so aerobic exercise can improve blood flow. Um, it can improve glucose metabolism, too. It can. I mean, you probably know more, way more about these things than I do. But, um, uh, there's research in animal models to suggest that exercise can increase neurogenesis, which is the creation of new cells in the hippocampus. That may be a factor as well. Um, but then there's the indirect factors, which is, uh, we know that, uh, stress, uh, aerobic exercise can dramatically reduce the negative aspects of stress, can reduce inflammation. It can affect sleep and improve sleep. It can improve emotion regulation. I mean, the benefits are just all over the place. But I think also it depends on people having the right attitude about it.

If you're doing exercise and it's stressing you out to do the exercise, that's probably counterproductive. And I think you want to benefit from the holistic impact. As opposed to focusing again, in a very narrow way on if I do. We talked about this. If I do 45 minutes a day, and I hate every minute of it, that's probably not going to be as good for you.

Let's just talk about stress. Okay? You mentioned the inverted u curve before. I think it's such a relevant topic. So many people are worried about their memory. They're worried that it's getting worse at an earlier age? Do you think across society, we are struggling with our memories at earlier ages now because of the ways that we're living?

As a scientist, I can't say. I just don't know. And I know it's a disappointing answer.

I appreciate the honesty.

Yeah, yeah. It's like. But I think we can look at that question, though, and say, can we, can we do better in terms of remember with age? We know for a fact that if you track people, even who are in the older ages, like 60 or something like that, you track that person over ten years. What you find is that in a big study, you look at the average, and the average will show a reduction in memory over that ten year period. But now you start to tease it apart and you look at individuals, some people are dramatically dropping off in that ten years, and some people are fine and they're maintaining their functioning well into old age. And. And we've. You can you and I know of people like this, right? And I was very compelled watching that Netflix special and the blue zones. I think you probably know about this, about places where people have a lifestyle that allows them to live into the hundreds sometimes, or, I mean, past the age of 100. And so there's lots of research right now on these superagers and flipping the script from thinking about aging in this negative light to thinking about how can we preserve our functions and thrive into old age.

Maybe that doesn't speak to this issue about the thirties and the way we're living, but we can come back to that, too.

That's fascinating. It makes you think about the wider societal view of aging, which is largely negative in a country like the UK or in a country like America. An almost expectation that you are going to decline as you get older. Of course your memory is going to be poorer. Of course your cognition is going to be less than what it was. And I don't agree with that. So I guess I'd love your comments on that. But also, what aspects of our memory might get better as we get older?

Well, we know that semantic memory or knowledge about the world can be preserved or improve as we get older. Also, as it turns out, people tend to have more of an optimistic view of the world, which leads them to have more of a bias to remember positive memories, which actually can be a very good thing. So these kinds of aspects of memory are preserved. It's really the episodic memory that changes. But I'd like your listeners to pause for just a moment on this question. And rather than thinking about, like, how can we remember as much as possible, think about what it means to have a better memory in the first place. And this is something that I really enjoyed writing in the book, which is that let's pause and just think about what the human lifespan is like. We have this long period of time where the brain is developing, and episodic memory, at least as the lab people will tell you, is actually not that good until you reach about young adulthood, maybe 20 to 30, and then it's functioning at its peak, so to speak.

Is that why we struggle to remember episodes from childhood?

Yes.

Or one of the reasons.

One of the reasons, yeah, context is another because you don't remember what it was like to be a child. But definitely that's a part of it for sure. But then as we pass 30, on average, memory starts to decline. So I looked at this and I said, God, this is such a horrible thing. Why were we designed to have this narrow window of time and recognitively optimal. But if you really look at it, the human lifespan is very weird. We have, like, this long period of development, many animals don't. Many animals are born and they have maybe a couple of months, and then they're at the adult level of the brain, then they're no longer capable of reproduction and they die. Humans are really weird species in that we have this long, we have the capability to live long past reproduction, and theres just not a whole lot of species that have menopause. So one of the things you have to think about is why, from an evolutionary perspective, do we have this long period of time where were alive, but we cant reproduce and yet were losing our cognitive function? And one idea which I really latched onto and I just love because, especially you and I come from indian cultures, where the attitudes about aging are very different.

And if we just focus on the aging end of the spectrum, one of the things that you see is that in many traditional cultures, older people are not trying to live like younger people. There's a change in the function of the elders relative to young people. Young people are going out, they're hunting, they're gathering, they're foraging, blah, blah, blah. But the older people are passing on the wisdom that they've accumulated. They're teaching children, passing on traditions, language, cultural tradition. And it's not about me. It's not about forming new memories for myself. It's about sharing what I've learned with younger people and what I find so valuable about that perspective. It just fits with the way the brain changes as we age. And it's not about, like, having optimal is really all about this cultural context and what we should be doing in the first place. And another species that lives long past reproduction is orcas. I just went in a deep rabbit hole about this because orcas experience menopause. And guess who leads a pod of orcas? Postmenopausal females. I just blew my mind when I read that. And they're the ones that teach this pot of orcas that you're going to hunt sharks because you can grab the liver and it's very tasty.

Or they teach the language and the cultural influences to pods of orcas, which I just love. I fascinated by orcas. And I think this is a really important takeaway for people to have, is that we need to change the way we think about aging and cognition, not to a perspective of more, more, more. Or how can I be the person that I was at 20 to think about? How can I be the person that I want to be as a senior and embrace these stages? Like, because in Hinduism, for instance, and other religious traditions, there are stages in life, and we don't view that as a bad thing.

I love that. I just love what you just said, and I think it's so apt. They're not trying to be who they were in their twenties when they're 80. It's not about, can I still lift the same weight as in my twenties? Can I still run as fast? No, of course, you probably can't. That's okay. It doesn't mean you're declining. You're changing.

Changing, exactly. And that's why we have plastic brains even into old age.

Yeah, no, I love that. Let's just go back to stress. We covered food, movement. We touched a little bit on sleep and how important sleep is for memory. You write in the book about napping, I think, and how napping can help us enhance memories. I just want to pause on stress because I think many people are feeling that their lives are very, very stressful. I've also seen those inverted new grass where a little bit of stress is good for our memory and then too much, and you start to get these diminishing returns until it's downright toxic, worse than actually in the first place. Do you know what's happening? You know, the example I often use is, you know, again, if you're giving a talk in public and you feel a little bit nervous and you're feeling a little bit of stress, it's not a bad thing. Your brain's going to work better, you're going to pull different bits of information and be able to articulate these ideas because of that little bit of stress. But if it gets too much, you freeze. You can't think of anything. You don't know what to say. And, of course, chronic stress, over time, we know, kills nerve cells in the hippocampus, for example, one of the key memory centers of the brain.

So how do you see stress and its impact on memory?

Well, I'm not an expert on stress and memory, but we've definitely studied this topic, and your summary was spot on. In terms of the chronic stress being especially the most problematic for the brain, it's bad for the hippocampus. It's bad for the prefrontal cortex, too. And when we're under stress, the other part of it is, even in the moment of stress, the prefrontal cortex is kind of downregulated.

What does that mean for people?

That means that it's harder, basically, to try to control memory. So, in other words, retrieving memories under stress can often be quite poor, because essentially our brains are in a mode to be reactive to the environment. It's not necessarily about planning and participating. It's responding in the moment.

Is that then, let's say a parent is trying to get their kids out of the front door to school. They know they're running late, and they can't find the car keys. Never been in that situation myself before, but just imagining if that makes for.

A friend, just asking for a friend.

Right. So in that moment, if we apply what you just said, because there's stress, it's going to be even harder to remember where your car keys are, is that right?

Absolutely, yes, absolutely.

And trying more and more and getting more and more flustered is in many ways the worst thing to do.

Yes. Yeah, absolutely. Absolutely. Taking a deep breath, on the other hand, and just grounding yourself for a moment, taking that pause, can be a much better thing to do.

Okay.

And one of the things that I think people really need to think about with chronic stress is our brains did not necessarily evolve for the lifestyles that we live now. I'm very moved by the books of Robert Sapolsky, for instance, who studied the effects of stress and baboons. And one of the things that you see is that social status has such a big effect on stress. And I think, especially if you're in kind of a precarious state, that can drive a lot of these stress systems. In my clinical work, you learn all about this, is that stress and anxiety which is basically another form of label for stress. The two key predictors are unpredictability and uncontrollability. So if you're being chased by. If you're a mouse and you're being chased by a cat, there's no, you know exactly what to do. Run like hell. You're not going to think about it. It's done. But if you're a mouse and you're running around and you don't know where the cat is and somewhere, but you don't know where it is, and so it's unpredictable threat. And then once it comes, if you can't do anything about it, that's stress.

Right. And so I think a lot of people are in environments that have this kind of, have this kind of chaos to them. Children, for instance, in very abusive homes, suffer from this kind of thing where it's like the parents are unpredictable and you never know what can happen in a moment's notice. They have very little control of their environments, and that's horrible. But also people, adults in abusive relationships can have this, too. And I think to some extent, people, I don't know this. And so this is like where we get in the realm of speculation. But I don't think it's hard to imagine that people who are particularly sensitive can be in an unstable work environment where they never know what can happen at any moment, and they feel that sense of unpredictability and uncontrollability. Now, ultimately, our perceptions of our experience are based on our beliefs and so forth and the way we frame experiences. And so to some extent, two people can have the exact same experience into one, it's stress, and to another, it's not. I mean, this is actually, I saw a very recent paper on this who's someone who studied rats in the neuroscience of stress.

And what he said is, you know what? It's true that stress hormones can have these bad effects on memory and so forth in, you know, in chronic levels. But, you know, when an animal's mating, cortisol levels go up. You know, there's all sorts of things that we would view as positive for people. My friend Andy, who did a study of stress and memory, he studied skydivers. So these are people who are going up in a plane and they're about to jump out of the plane on their own volition. And yet you see this dramatic rise in cortisol levels right before you go out. So part of the body's stress response, the brain's stress responses, are not necessarily going to have the same effects if your mindset is different. Right. Being chased by someone with a knife versus, you know, snowboarding on a, you know, on a advanced, like a course or whatever, those two things are going to drive a lot of the same noradrenergic responses, but psychologically they're very different and they're going to have different effects on the brain function in the long term.

Yeah, that's actually, I think, one of the most empowering things, of course, being chased by a knife is a real threat, and I get that. And, you know, that requires you to take certain steps to make sure you're safe. But most of the things, many of the things we experience in life, we can change, whether they are actually stressful or not, by our perception, by training ourselves to look at it from a different viewpoint, things we were talking about differently.

Right.

You know, updating that experience and putting a different spin on it. I think these are really, really empowering things. You mentioned, or we mentioned hidden memories, or these kind of. What was the word you used?

Didn't use hidden, latent or dormant.

Yeah. I'm reminded of the story that Doctor Gabor Massey shared, I think, last week about a Haida individual, Haida being an indigenous community, I think, in Canada. And she was saying how until the age of five, she could speak fluent Haida. And at some point in her life, I think later on in childhood, she was put into the mainstream schools. And if my recollection is correct, he was saying that if she ever spoke a word of Haida, they would beat her. So she had to learn English, basically. And in her twenties or thirties, she was saying like, I cannot remember a word of Haida. And even in situations where people are speaking, it's like she knew it and it's gone. For what you know about memory, can something like that truly have gone? Or because of the heavy, heavy trauma has somewhere in her brain, it's been decided that we need to suppress that, because it is dangerous. It is dangerous to utter a word of Haida. So perhaps in the right situation, with the right key, that you could unlock that. I mean, how would you see that?

I would say that it's unlikely that those memories are repressed per se, in the sense that just unconsciously the brain is trying to hide it away. But what I would say is that it's very possible that you learn to suppress the memories consciously, and I'm sure somebody in that situation would learn to suppress them. So my friend Mike Anderson, who's in Cambridge, has actually studied this and shown that, in fact, people can lose access to memories just from being. Suppressing them over and over and over again. But that doesn't necessarily mean that they're gone. So one thing that I talk about in my book, which is a happier version of this, is flying back to India to visit my relatives there and talking about the experience of getting off the plane. And have you been to India?

Funnily enough, that bit in the book so resonated with me because I went last year, just over twelve months ago for the first time in quite a few years, and it was as if I'd never been away.

Yeah.

It just reminded me of my childhood. We used to go every other summer, basically for the entire summer holidays.

Yeah.

And I was like, yeah.

Just. It just.

It felt very, very familiar.

Yeah. Yeah. There's certain sights and sounds and smells that only happen there. The colors are brighter. The smells are more intense, sometimes terrible, sometimes brilliant and just intoxicating. The sound of the birds, the sound of some blown speaker that's producing prayers at a mosque or something like that, the guy selling the newspaper. And it's like that context brings out memories that were dormant before. And so it's certainly possible for somebody to be back in a community that they've been away from and access those kinds of memories. We also see, for whatever reason, people will report being more likely to engage in their first language as they get very old. And maybe it happens because you start to lose access to the, especially, like, as you're getting much, much older, lose access to some of those memories that are, say, not as important from the recent years. And the memories that stick with you and you come back to over and over and over again are more from those formative years. And that might be a factor as well, that people can. As you revisit those periods of your life more, it's easier to pull out the parts of you from those periods of time.

Yeah. Taran, look, I have so enjoyed this conversation. It's gone into so many different areas. As I mentioned to you when you came to my house first thing this morning, the book is just fabulous. Why we remember the science of memory and how it shapes us. There are so many new and fresh insights in there about a topic that I think we all deeply, deeply care about. We've covered a lot. Of course, there's plenty we haven't covered. Having spent years studying memory, having spent years writing this book, what are some of the key messages? Why the end here that you want to leave my audience with?

Remember better, not more. So if you look at the brain. It's always a less is more, less is more principle, meaning that you get the most out of as little as possible. So I would encourage people to really focus on not trying to take everything with them, but actually taking their experiences, saying, what do I want to take with me? What are the memories that I want to take with me? Whether it's like sitting in a concert and deciding whether to spend it taking a movie, or whether it's deciding, do I want to spend my time away from work watching tv versus taking a holiday with my family. I mean, these are, you never know when the opportunity is to make a great memory out of something. And I think the other thing that I really like people to take away is this idea that memory is this incredible resource. It can be something that we can draw upon to be better people. It can be something we can draw upon to elicit more happiness or something that can help us in times of, you know, when we're uncertain. But it can also. You don't want it in the driver's seat.

You want it as the copilot. You don't want memory to be driving you to make bad decisions because you're not pausing and taking time to evaluate the influence. Because I think one of the things that, that we often do is we become so busy and we're moving so quickly, we lose those moments of pause where we can control memory and use it towards our goals as opposed to having it feed into our biases and feeding into habits and that are bad and counterproductive behaviors.

Yeah, love it. It's been a real joy talking to you. Thank you for writing such a wonderful book and thanks for making time to come on the show.

Thank you so much for having me. I hope we can do this again sometime.

Yeah, me too. Really hope you enjoyed that conversation. Do think about one thing that you can take away and apply into your own life. And also have a think about one thing from this conversation that you can teach to somebody else. Remember, when you teach someone, it not only helps them, it also helps helps you learn and retain the information. Now, before you go, just wanted to let you know about Friday five. It's my free weekly email containing five simple ideas to improve your health and happiness. In that email, I share exclusive insights that I do not share anywhere else, including health advice, how to manage your time better, interesting articles or videos that I'd be consuming, and quotes that have caused me to stop and reflect. And I have to say, in a world of endless emails, it really is delightful that many of you tell me. It is one of the only weekly emails that you actively look forward to receiving, so if that sounds like something you would like to receive each and every Friday, you can sign up for free@drchataji.com. Friday five if you are new to my podcast, you may be interested to know that I have written five books that have been bestsellers all over the world covering all kinds of different topics, happiness, food, stress, sleep, behavior change and movement, weight loss and so much more.

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