WEBVTT - Special Episode: Dr. Charan Ranganath & Why We Remember 0:00:43.680 --> 0:00:47.360 Hi, I'm Aaron Welsh, and this is this podcast will 0:00:47.440 --> 0:00:51.360 Kill You. Welcome to another of our tp w k 0:00:51.640 --> 0:00:55.040 Y book Club episodes, where we get to explore a 0:00:55.120 --> 0:00:59.279 science or medicine book beyond the pages by asking the 0:00:59.320 --> 0:01:03.360 author all sorts of questions for about forty five minutes 0:01:03.440 --> 0:01:06.600 or so. As you've probably heard me say, it's one 0:01:06.640 --> 0:01:10.000 of my favorite parts of putting this podcast together, and 0:01:10.080 --> 0:01:12.720 I hope that you're enjoying it too. If you are 0:01:13.040 --> 0:01:15.520 or if you're not, we'd love to hear from you. 0:01:15.880 --> 0:01:19.560 Send us your thoughts, your unanswered questions, your book suggestions, 0:01:19.640 --> 0:01:22.880 your favorite selections, and anything else you want to tell 0:01:22.959 --> 0:01:26.440 us to us via the contact us form on our 0:01:26.440 --> 0:01:30.560 website This Podcast will Kill You dot com. Speaking of 0:01:30.600 --> 0:01:33.960 our website, did you know that you can find all 0:01:34.040 --> 0:01:37.279 of the books we've covered so far this season and last, 0:01:37.680 --> 0:01:39.520 as well as the books that we'll be getting to 0:01:39.640 --> 0:01:42.920 later this year on our website. All you have to 0:01:42.959 --> 0:01:45.480 do is head over to our website and click on 0:01:45.560 --> 0:01:48.440 the link to our bookshop dot org affiliate account under 0:01:48.480 --> 0:01:52.320 the extras tab. Once you're on bookshop, you'll find various 0:01:52.360 --> 0:01:58.360 TPWKY associated booklists, including one for book Club Pro tip. 0:01:58.560 --> 0:02:02.240 These lists are good great for finding future reads or 0:02:02.360 --> 0:02:05.800 picking out gifts for the bookworms in your life. So 0:02:06.200 --> 0:02:10.160 with that shall we get into this week's book. I 0:02:10.200 --> 0:02:13.639 am delighted to share with you all a book whose 0:02:13.720 --> 0:02:19.079 subject literally all of us can relate to. Why we remember? 0:02:19.560 --> 0:02:23.359 Unlocking Memories, Power to hold on to What Matters? By 0:02:23.440 --> 0:02:29.440 Doctor Charan Ranganath. In this fascinating and insightful book, Ranganath 0:02:29.680 --> 0:02:34.080 expertly guides readers through complex concepts of how memory works 0:02:34.240 --> 0:02:38.640 and what happens when it doesn't, how memories are formed, forgotten, 0:02:38.960 --> 0:02:42.800 or forged, and what studying the mechanisms of our memory 0:02:42.880 --> 0:02:45.640 can tell us about our past as well as our present. 0:02:46.440 --> 0:02:51.120 An expert is no exaggeration. Doctor Ronganath is Professor of 0:02:51.160 --> 0:02:55.440 Psychology and Neuroscience and Director of the Dynamic Memory Lab 0:02:55.480 --> 0:02:59.120 at the University of California at Davis, and his work 0:02:59.160 --> 0:03:03.120 has investigated the neural underpinnings of how memories are made, 0:03:03.600 --> 0:03:07.160 what happens when we retrieve memories, and how things like 0:03:07.280 --> 0:03:13.239 emotions influence our recollection. We've all had those moments where 0:03:13.280 --> 0:03:16.680 we can't remember where we put our keys, or when 0:03:16.760 --> 0:03:20.320 we've typed in eight different passwords to that one random 0:03:20.360 --> 0:03:23.040 website we had to make an account four years ago, 0:03:23.360 --> 0:03:26.560 only to get locked out on our ninth try, Or 0:03:26.600 --> 0:03:30.280 when we struggle to remember that colleague's partner's name whom 0:03:30.320 --> 0:03:36.080 we met literally three minutes ago. I forget easily, easily 0:03:36.560 --> 0:03:39.600 ninety percent of some of the episodes we've released, like 0:03:39.760 --> 0:03:43.480 don't ask me anything about arsenic at this point, And 0:03:43.640 --> 0:03:46.440 there have been at least a few times where Aaron 0:03:46.640 --> 0:03:50.000 or I will suggest a topic that we've already done 0:03:50.040 --> 0:03:54.720 an episode on, having completely forgotten that we've already covered it. 0:03:55.400 --> 0:03:59.400 Sometimes it really does feel like our brain is sabotaging us, 0:03:59.680 --> 0:04:03.000 making us forget things that can be quite important, like 0:04:03.320 --> 0:04:05.400 whether or not you turn to the oven off as 0:04:05.440 --> 0:04:08.720 you sit on an international flight, while at the same 0:04:08.800 --> 0:04:16.240 time preserving the cringiest, most embarrassing, painful moments in exquisitely 0:04:16.520 --> 0:04:21.080 vivid detail so we can easily recall them at say, 0:04:21.279 --> 0:04:24.800 three am, when we're tossing and turning and our anxiety 0:04:25.000 --> 0:04:29.960 is at its peak. Complaining about our forgetfulness is a 0:04:30.000 --> 0:04:33.360 favorite pastime for many of us, but we don't often 0:04:33.400 --> 0:04:36.920 stop to consider why we remember in the first place, 0:04:37.640 --> 0:04:41.640 and how examining the role of memory over our evolutionary 0:04:41.720 --> 0:04:46.600 history can help to answer that question. In Why We Remember, 0:04:46.920 --> 0:04:51.080 Ranganath delves into this question and guides readers down many 0:04:51.120 --> 0:04:56.240 other roads relating to memory, including how we remember, the 0:04:56.320 --> 0:05:00.599 differences between different types of memory, like how is remembering 0:05:00.880 --> 0:05:05.920 your sixth birthday different from recalling the date the Titanic 0:05:06.000 --> 0:05:10.680 set sail at your favorite bars trivia night, How context 0:05:10.880 --> 0:05:15.040 like music or smell can strengthen our recall, the world 0:05:15.080 --> 0:05:20.200 of competitive memory, the unreliability of memory, how dejaus vous works, 0:05:20.400 --> 0:05:23.719 and even ways we can work at improving our memory. 0:05:24.640 --> 0:05:28.440 The neuroscience of memory is, as you can imagine, an 0:05:28.560 --> 0:05:32.400 incredibly complex topic where it would be so easy to 0:05:32.400 --> 0:05:36.360 get lost in the weeds, but doctor Ranganeth ensures that 0:05:36.400 --> 0:05:40.680 doesn't happen with his wonderfully clear and engaging writing. This 0:05:40.960 --> 0:05:44.080 is sure to be an episode you won't forget, at 0:05:44.160 --> 0:05:47.320 least for a while anyway, So let's get right to 0:05:47.400 --> 0:06:16.640 it after this break, doctor Ranganath, thank you so much 0:06:16.680 --> 0:06:20.320 for being here today. I absolutely devoured your book. I 0:06:20.360 --> 0:06:24.200 found it incredibly fascinating, could not put it down, and 0:06:24.320 --> 0:06:27.520 I wondered, you know, when did you decide I want 0:06:27.520 --> 0:06:31.040 to write a book about memory and two parter, how 0:06:31.040 --> 0:06:33.919 did you first become interested in researching memory? 0:06:34.800 --> 0:06:39.159 Great two part question. I got actually a background in 0:06:39.200 --> 0:06:43.240 clinical psychology in graduate school, and so initially my work 0:06:43.320 --> 0:06:46.080 was on depression, and I would see a lot of patients, 0:06:46.120 --> 0:06:49.760 and some of my time was actually seeing people, for instance, 0:06:49.760 --> 0:06:53.839 in treatment for depression or anxiety, and sometimes it was 0:06:53.880 --> 0:06:57.000 working in the neuropsychology clinic where people would be coming 0:06:57.040 --> 0:06:59.159 in and they would be worried, you know, do I 0:06:59.200 --> 0:07:02.240 have Alzheimer's disease or you know, maybe they had a 0:07:02.240 --> 0:07:06.280 car accident and an insurance claim and so forth. And 0:07:06.400 --> 0:07:10.360 so what was interesting is almost everyone who came into 0:07:10.360 --> 0:07:13.960 the neuropsychology clinic, whether or not it was their main problem, 0:07:14.080 --> 0:07:16.840 the thing that brought them in was almost always memory 0:07:17.120 --> 0:07:20.480 that they said they had a memory problem. And when 0:07:20.880 --> 0:07:24.400 I was working with patients, what I found was early 0:07:24.480 --> 0:07:26.920 on I was working, for instance, with my first patient 0:07:26.960 --> 0:07:30.120 was a phobia patient and he had a driving phobia, 0:07:30.760 --> 0:07:34.080 and so we worked through a lot of the mechanics 0:07:34.200 --> 0:07:38.600 of that, which is basically just exposure to drive drive drive, 0:07:39.360 --> 0:07:43.880 but he wasn't quite happy, and it wasn't until we 0:07:43.960 --> 0:07:46.400 really kind of got into a little bit of his 0:07:46.560 --> 0:07:50.440 memories around that time that he felt like he was 0:07:50.480 --> 0:07:54.720 really satisfied and he had actually, it turns out, a 0:07:54.760 --> 0:07:57.560 falling out with his father right before this car accident, 0:07:57.720 --> 0:08:00.600 and it was all at least for him, there is 0:08:00.640 --> 0:08:03.800 a deep link between them, and so it was just 0:08:03.920 --> 0:08:06.320 over and over again. I would see these links to 0:08:06.400 --> 0:08:09.760 memory throughout my clinical practice, in my training, that is, 0:08:10.200 --> 0:08:12.760 and at the same time, there were these new advances 0:08:12.800 --> 0:08:16.360 coming up in brain imaging. And what was great about 0:08:16.400 --> 0:08:18.640 that was that a lot of the way we were 0:08:18.680 --> 0:08:23.600 thinking about memory in the clinic was really not grounded 0:08:23.640 --> 0:08:26.760 in the best science that was around. It was more 0:08:26.840 --> 0:08:31.000 based on what was useful in the clinic. But I 0:08:31.000 --> 0:08:33.439 felt like, if we can actually get into people's brains, 0:08:33.480 --> 0:08:36.400 we can really figure out what's going on. And so 0:08:36.559 --> 0:08:38.760 that's how I ended up getting into the world of 0:08:38.800 --> 0:08:43.479 memory research. And over the years, you know, I've always 0:08:43.960 --> 0:08:46.400 I've really felt like I wanted to write a book 0:08:46.440 --> 0:08:49.040 for regular people because I never really felt like I 0:08:49.040 --> 0:08:51.400 would have gone this road. I feel like a very 0:08:51.480 --> 0:08:57.319 unlikely scientist, and so I wanted to write something for 0:08:57.760 --> 0:09:01.280 you know, everyone, to share science and where it's going, 0:09:01.360 --> 0:09:03.679 where it's gone and what we've learned from it, And 0:09:03.720 --> 0:09:07.000 again that kind of stems back to my interests of 0:09:07.040 --> 0:09:09.600 bringing a scientific perspective back to a lot of the 0:09:09.600 --> 0:09:12.960 clinical work. And so I just didn't think I was 0:09:13.000 --> 0:09:15.240 ready yet. I didn't think I had the book in 0:09:15.320 --> 0:09:18.000 me yet. I didn't think I had the time. And 0:09:18.480 --> 0:09:21.480 my agent, Rachel, actually she'd contacted me out of the 0:09:21.520 --> 0:09:27.080 blue in March of twenty twenty, and so we had 0:09:27.320 --> 0:09:29.480 an appointment to get together. I think it was the 0:09:29.520 --> 0:09:33.000 second or the third week of March, and two days 0:09:33.040 --> 0:09:35.840 beforehand turned out we had to cancel it because of 0:09:35.840 --> 0:09:39.360 the lockdowns, And it was like the universe was just 0:09:39.400 --> 0:09:42.280 telling me write this book. And then, you know, it 0:09:42.320 --> 0:09:44.680 was really just became apparent to me just how much 0:09:44.720 --> 0:09:49.400 people need to hear from scientists, not just journalists, not 0:09:49.600 --> 0:09:53.840 just politicians who were up on the science, but scientists themselves, 0:09:54.520 --> 0:09:57.439 especially because there's so much We talked about this a 0:09:57.520 --> 0:10:01.800 little bit in the beginning before we started recording, that 0:10:02.480 --> 0:10:06.120 a big part of science is actually having some degree 0:10:06.120 --> 0:10:08.920 of uncertainty, some degree of not knowing. I mean, that's 0:10:08.960 --> 0:10:12.080 actually a big part of science in general, is figuring 0:10:12.120 --> 0:10:15.360 out what we don't know and so I think people 0:10:15.440 --> 0:10:20.360 wanted facts at the beginning of the pandemic, and that's 0:10:20.559 --> 0:10:23.680 you know, that's how we are taught science in high 0:10:23.679 --> 0:10:26.160 school is this is just a boatload of facts that 0:10:26.200 --> 0:10:29.000 you have to memorize, and it's really a process, and 0:10:29.040 --> 0:10:32.240 it's an evolving process, and one in which you go 0:10:32.280 --> 0:10:35.240 into the trenches and you're kind of you're trying to 0:10:35.280 --> 0:10:38.120 figure out nature, but you're also fighting nature. It's a 0:10:39.160 --> 0:10:43.440 trying to figure this stuff out, and there's uncertainty involved 0:10:43.440 --> 0:10:47.120 with that, and I feel like if scientists were getting 0:10:47.160 --> 0:10:50.760 to people, we could say more about both the uncertainty 0:10:50.880 --> 0:10:53.920 and also about some of the educated guesses that we 0:10:53.960 --> 0:10:55.520 can make based on what's out there. 0:10:56.360 --> 0:11:00.000 Do you point out in the introduction that we shouldn't 0:11:00.160 --> 0:11:03.040 be asking why do we forget? Or why am I 0:11:03.080 --> 0:11:07.640 so forgetful? But rather the more interesting question, and also 0:11:07.760 --> 0:11:11.120 of course the inspiration for your book's title, why do 0:11:11.200 --> 0:11:14.280 we remember? And for the full answer to that question, 0:11:14.440 --> 0:11:17.400 I'll direct our listeners to your wonderful book, But for now, 0:11:17.440 --> 0:11:19.520 could you just give us a brief overview? 0:11:21.040 --> 0:11:25.040 Happy too. So, basically, when I was approached to write 0:11:25.040 --> 0:11:26.480 a book, you know, there was a little bit of 0:11:26.520 --> 0:11:28.520 a talk of writing a book to tell people to 0:11:28.640 --> 0:11:32.160 improve their memories, and I'm all for that, but that 0:11:32.200 --> 0:11:34.959 book has been written by a lot of people, and 0:11:35.600 --> 0:11:39.920 really I wanted to give people a scientific perspective on 0:11:40.880 --> 0:11:44.240 what memory seems to be for and combating a lot 0:11:44.280 --> 0:11:46.600 of myths people have about memory. I think a lot 0:11:46.679 --> 0:11:50.680 of us expect that we're supposed to remember everything and 0:11:50.720 --> 0:11:55.400 it's supposed to be effortless. And the earliest scientific studies 0:11:55.400 --> 0:11:58.280 of memory, where we started to quantify how much people remember, 0:12:00.200 --> 0:12:03.880 it was pretty well known that about sixty percent of 0:12:03.880 --> 0:12:08.120 what you've experienced will be forgotten in twenty four hours. 0:12:08.200 --> 0:12:13.360 So that is probably the best case scenario in certain ways. 0:12:14.040 --> 0:12:17.280 But here's the thing. If the scigence has shown this 0:12:17.520 --> 0:12:20.880 over and over and over again, much of maybe most 0:12:21.040 --> 0:12:24.880 of what we experienced we won't remember that we will forget, 0:12:24.960 --> 0:12:27.920 I should say, then the real question is why do 0:12:28.000 --> 0:12:31.440 we remember anything in the first place. And I think 0:12:31.480 --> 0:12:34.280 that the answer to this has come out not so 0:12:34.400 --> 0:12:37.640 much in terms of memories replaying the past, as much 0:12:37.679 --> 0:12:42.040 as about memory being this resource that we're expected to 0:12:42.120 --> 0:12:43.880 draw upon in the present in the future. 0:12:45.360 --> 0:12:47.679 Let's take a quick break and when we get back, 0:12:47.800 --> 0:13:08.160 There's still so much to discuss. Welcome back everyone. I've 0:13:08.200 --> 0:13:11.600 been chatting with doctor Charan Ranganath about his book Why 0:13:11.679 --> 0:13:15.880 We Remember, Unlocking Memories, Power to hold on to what matters. 0:13:16.360 --> 0:13:21.480 Let's get back into things. You also mentioned different types 0:13:21.559 --> 0:13:26.199 of memory or broad categories of memory. First, what are 0:13:26.240 --> 0:13:28.959 those different types of memory and how do we use 0:13:29.120 --> 0:13:32.440 each of these types of memories in different ways? 0:13:33.679 --> 0:13:36.840 In the book, I talk about especially what I study, 0:13:36.920 --> 0:13:41.080 which is episodic memory, which is your ability to recall 0:13:41.200 --> 0:13:44.760 a specific event. You know, recall your first date, or 0:13:44.840 --> 0:13:48.679 recall that time that the Dallas Cowboys won the Super 0:13:48.720 --> 0:13:51.760 Bowl or whatever it is that you look back on 0:13:51.840 --> 0:13:55.040 and reminisce about. Right, And those are events that are 0:13:55.080 --> 0:13:59.840 singular experiences in your life. Now, I should say, in 0:14:00.080 --> 0:14:04.240 neuroscience we're often obsessed with just splitting all these different 0:14:04.320 --> 0:14:07.160 kinds of memory into different boxes and so forth. I 0:14:07.200 --> 0:14:09.560 think in the real world there's a lot more interaction 0:14:10.200 --> 0:14:13.160 than we think between these different kinds of memory. So 0:14:13.320 --> 0:14:15.920 this is a little bit of an abstraction, I should say, right, 0:14:16.960 --> 0:14:19.000 And I'll get into that more, I'm sure later in 0:14:19.040 --> 0:14:22.240 the conversation. But there's another kind of memory that I'm 0:14:22.240 --> 0:14:25.280 interested in too, which is semantic memory, which is our 0:14:25.480 --> 0:14:29.920 general knowledge about the world. Right. So your general knowledge 0:14:29.920 --> 0:14:33.840 about the world you can apply anywhere, but episodic memory 0:14:33.880 --> 0:14:36.840 is specific to a time in a place. And what's 0:14:36.920 --> 0:14:39.960 cool about that is semantic memory is something that you 0:14:40.120 --> 0:14:43.200 learn very slowly, kind of like the way chat GPT 0:14:43.680 --> 0:14:47.760 learns about languages, like feeding it gobs and gobs of information. 0:14:48.880 --> 0:14:53.440 But episodic memory gives you this ability to mentally stop 0:14:53.480 --> 0:14:56.720 on a dime and take a take a U turn 0:14:56.760 --> 0:14:59.520 if you need to. In other words, once you learn 0:14:59.560 --> 0:15:03.080 about thing that's kind of exceptional, you can change, you 0:15:03.120 --> 0:15:06.440 can rotate your worldview in really interesting ways. Right. So 0:15:07.200 --> 0:15:10.160 you're dating someone, right, and then you find out that 0:15:10.240 --> 0:15:13.000 they've been texting with someone else on a you know, 0:15:13.320 --> 0:15:15.360 on a dating app or something like that, Right, and 0:15:15.920 --> 0:15:18.440 now you want to go back and change a lot 0:15:18.480 --> 0:15:22.280 of your assessments of this person that you're dating. And 0:15:22.360 --> 0:15:27.040 so that's just one example of how having these different 0:15:27.120 --> 0:15:31.040 kinds of memories allow you much more flexibility and allow 0:15:31.080 --> 0:15:31.960 you to learn quickly. 0:15:33.240 --> 0:15:37.480 Memory evolved in a different evolutionary context than the one 0:15:37.520 --> 0:15:41.680 that we currently find ourselves in. How did our ancestors 0:15:41.840 --> 0:15:45.960 use memory differently than we do now, and what implications 0:15:46.040 --> 0:15:49.680 does that have for us modern humans? You know, trying 0:15:49.720 --> 0:15:52.320 to remember that person that we just met at a 0:15:52.360 --> 0:15:54.760 work function and we're like, oh, their name, I can't 0:15:54.760 --> 0:15:58.440 remember their name? What is their face? Like everything? How 0:15:58.440 --> 0:16:01.760 does this affect what our memory prioritizes. 0:16:03.320 --> 0:16:06.640 It's useful to start off with just how our memories 0:16:06.800 --> 0:16:10.000 formed in the first place. And one of the no 0:16:10.040 --> 0:16:13.800 matter what kind of memory you're talking about, the general 0:16:13.840 --> 0:16:16.720 theory goes is that you have neurons, which are the 0:16:16.760 --> 0:16:19.920 basic computational unit of the brain. They're all these individual 0:16:20.040 --> 0:16:23.440 cells in our brain, but they're connected to each other 0:16:23.800 --> 0:16:25.800 and that in a way that allows them to talk 0:16:25.840 --> 0:16:29.520 to each other. And we think that through experience, no 0:16:29.560 --> 0:16:32.400 matter what kind of a smaller, big neural circuit you're 0:16:32.440 --> 0:16:36.440 talking about, those connections are tweaked and they change. And 0:16:36.480 --> 0:16:40.600 what that allows us to do is build associations between 0:16:40.720 --> 0:16:45.880 different things that we're experiencing. So even very very so 0:16:45.960 --> 0:16:51.000 called primitive organisms can learn the basic Hey, this thing 0:16:51.240 --> 0:16:53.720 is going to cause this effect in the world. This 0:16:53.760 --> 0:16:56.600 thing is going to be dangerous to me, this thing 0:16:56.680 --> 0:16:58.600 is going to be you know, a good source of 0:16:58.640 --> 0:17:01.600 food or whatever. Right, So those are just some basic 0:17:02.560 --> 0:17:05.480 ways in which memories can be formed, even in very 0:17:05.480 --> 0:17:09.879 simple nervous systems. But what's interesting is is that a 0:17:09.920 --> 0:17:13.119 lot of times that plasticity, the changes in those connections, 0:17:13.200 --> 0:17:18.639 is temporary, and often a way in which those connections, 0:17:18.640 --> 0:17:22.000 the changes are stabilized, comes from the release of these 0:17:22.040 --> 0:17:25.600 chemicals called neuromodulators. So I know you've talked about some 0:17:25.640 --> 0:17:29.520 of these in your show, dopamines one for instance, serotonin, 0:17:29.720 --> 0:17:33.399 norap and ephrin. These are things that people have often 0:17:33.440 --> 0:17:36.879 heard about, I think, and these are chemicals that are 0:17:36.880 --> 0:17:39.240 released in their brain that they don't cause neurons to 0:17:39.240 --> 0:17:42.639 be more just fire more or fire less, but they 0:17:42.760 --> 0:17:46.480 change the way processing happens. But they also stabilize plasticity. 0:17:47.359 --> 0:17:51.359 So why that's important is because these chemicals tend to 0:17:51.359 --> 0:17:54.960 be released, these neuromodulators, as we call them, tend to 0:17:55.000 --> 0:18:00.160 be released at particularly important times, times when you are 0:18:00.520 --> 0:18:02.959 you know, encountering something that gets you a state of 0:18:03.000 --> 0:18:06.400 desire or something that gets you know, when you're angry, 0:18:06.480 --> 0:18:10.840 you're scared, when you're stressed out. There are even you know, 0:18:11.000 --> 0:18:14.480 certain hormonal effects like you know, there's lots of stuff 0:18:14.520 --> 0:18:17.240 that happens. We're still figuring it out, but there's lots 0:18:17.240 --> 0:18:21.880 of stuff that happens after pregnancy that changes plasticity. There's 0:18:22.240 --> 0:18:26.040 so many different kinds of chemicals that can produce these changes, 0:18:26.359 --> 0:18:31.679 but they're all related to something important. And so that 0:18:31.840 --> 0:18:34.159 right there, to me is kind of a hint that 0:18:34.560 --> 0:18:38.680 memory is not about hoarding every experience that you have, 0:18:39.440 --> 0:18:42.520 but being more selective in terms of taking what you need. 0:18:43.720 --> 0:18:46.199 If you think about you brought up evolution, and I 0:18:46.320 --> 0:18:49.360 like to think of evolution mainly because it brings up 0:18:49.520 --> 0:18:54.600 this aspect of design constraints, right, So you can't have, like, 0:18:54.800 --> 0:18:58.000 you know, something that's great for hauling cargo and be 0:18:58.080 --> 0:19:01.560 the fastest car around. You got to make some choices. 0:19:01.680 --> 0:19:04.879 And so as a result, it's like in the brain, 0:19:04.920 --> 0:19:07.720 you could have something which is just like our phone. 0:19:07.880 --> 0:19:10.760 This is the massive storage capability of the stores everything 0:19:10.800 --> 0:19:14.480 we experienced exactly as we experience. And that's a hoarder's strategy. 0:19:14.880 --> 0:19:17.320 So you just hoard all these memories and then what 0:19:17.400 --> 0:19:19.480 you do with them, well, you can't really use them 0:19:19.480 --> 0:19:21.640 when you need them because you can't find what you're 0:19:21.680 --> 0:19:25.359 looking for. Or you could have this Marie Condos strategy 0:19:25.400 --> 0:19:27.639 of just taking these things that are valuable to you 0:19:27.680 --> 0:19:30.200 and bringing those along and saying goodbye to the rest. 0:19:30.520 --> 0:19:32.880 And I think that's the strategy that our brain is used. 0:19:32.880 --> 0:19:35.800 And you can see this quality over quantity trade off 0:19:35.880 --> 0:19:38.760 everywhere in the brain. Just in terms of even attention. 0:19:39.280 --> 0:19:42.560 We often think that everything we see, we're seeing everything 0:19:42.600 --> 0:19:45.240 in front of us, but really our eyes are moving 0:19:45.280 --> 0:19:49.000 around and just grabbing little high resolution bits of the world, 0:19:49.440 --> 0:19:51.960 and then our brain is using memory to some extent 0:19:52.040 --> 0:19:54.119 to really build a picture of what's in front of us. 0:19:54.200 --> 0:19:58.920 Right now, you explained a bit how memories are formed, 0:19:59.560 --> 0:20:04.280 how is a memory recalled, and do the processes or 0:20:04.320 --> 0:20:08.320 the parts of the brain involved differ depending upon the 0:20:08.359 --> 0:20:11.119 type of memory, you know, episodic or semantic. 0:20:12.080 --> 0:20:19.280 Great questions. So let's start with episodic memory. So there's 0:20:19.320 --> 0:20:21.760 an area of the brain called the hippocampus, which is 0:20:21.800 --> 0:20:25.120 probably one of the most glamorous areas of the brain. 0:20:25.200 --> 0:20:27.840 It's probably one of the most studied areas of the brain. 0:20:28.480 --> 0:20:32.840 And this area, on the one hand, it's evolutionarily very old. 0:20:32.920 --> 0:20:36.760 I mean even fish have a rudimentary hippocampus, and birds 0:20:36.800 --> 0:20:40.960 alone humans, right and so some of the theories go 0:20:41.119 --> 0:20:44.280 that the hippocampus evolved to tell us where we are, 0:20:45.080 --> 0:20:48.000 and I think the more modern perspective is it helps 0:20:48.080 --> 0:20:52.439 us track things in space and time. And so the 0:20:52.520 --> 0:20:55.480 hippocampus is basically saying, you know, we don't have a 0:20:55.520 --> 0:20:57.520 clock in our heads, we don't have a GPS in 0:20:57.560 --> 0:21:00.719 our heads. So to figure out where we are and 0:21:00.760 --> 0:21:03.320 when things are happening, it sort of has to put 0:21:03.359 --> 0:21:07.639 together all this arbitrary stuff that's happening and just glue 0:21:07.640 --> 0:21:11.160 it together and provide a little index that links everything 0:21:11.280 --> 0:21:14.080 just because they occurred at a particular place and time, right, 0:21:14.760 --> 0:21:18.679 And that's what we would call the context, so to speak. 0:21:19.280 --> 0:21:22.160 You know, as we're talking, you might have the scent 0:21:22.240 --> 0:21:24.680 of your dog in the background or something like that, right, 0:21:24.720 --> 0:21:27.360 you might have other things that are going on. You've 0:21:27.400 --> 0:21:29.600 got like this room in front of you, you got this 0:21:29.640 --> 0:21:31.680 big microphont frame. There are things that are just sort 0:21:31.720 --> 0:21:33.840 of in the background. But that's part of that context. 0:21:34.600 --> 0:21:38.719 And so one of the key features of episodic memory 0:21:38.760 --> 0:21:42.720 that explains a lot of its weirdness is that it's 0:21:42.840 --> 0:21:47.040 very sensitive to this context. So things like music, smells, 0:21:47.960 --> 0:21:51.359 being in a particular place. Those are all to the 0:21:51.359 --> 0:21:54.879 extent that they're unique contexts. They can just bring you 0:21:54.960 --> 0:21:58.200 back in time and give you the sense of literal 0:21:58.280 --> 0:22:01.440 time travel, where all of a sudden you're pushed back 0:22:01.520 --> 0:22:03.720 into a place in time that you haven't visited in 0:22:03.760 --> 0:22:04.480 a long time. 0:22:04.560 --> 0:22:04.720 Right. 0:22:05.119 --> 0:22:07.920 Songs are great for this because we tend to listen 0:22:07.960 --> 0:22:10.600 to songs during certain periods of our life, and so 0:22:11.359 --> 0:22:14.199 they're just these great tools for reminiscence because of that, 0:22:14.280 --> 0:22:17.959 because they were just the context, the soundtrack to our 0:22:18.000 --> 0:22:22.520 lives during these particular windows of time. So that's episodic memory. 0:22:23.400 --> 0:22:25.760 But there are other parts of the puzzle too. So 0:22:26.400 --> 0:22:32.040 sometimes our memories are these events are associated with things 0:22:32.080 --> 0:22:35.640 that again drive these sort of survival systems, and in particular, 0:22:37.080 --> 0:22:39.159 for instance, you can have things that scare us or 0:22:39.240 --> 0:22:43.040 stress us out right, and so when we retrieve those memories, 0:22:43.080 --> 0:22:47.040 they're accompanied by this sense, this visceral sense of rememory 0:22:47.080 --> 0:22:50.159 that's often like my heart's racing, or I'm just really 0:22:50.320 --> 0:22:54.240 aroused or stressed or worried or whatever it is. Right, 0:22:54.920 --> 0:22:57.080 And there's an area of the brain called the amygdala 0:22:57.640 --> 0:22:59.840 which seems to work with the hippn canvas but it 0:23:00.000 --> 0:23:04.359 really ties a lot of the important parts of a 0:23:04.440 --> 0:23:09.360 memory to those visceral responses that we have, so that 0:23:09.400 --> 0:23:13.240 the memory, when you retrieve it, you not only get 0:23:13.240 --> 0:23:15.800 this kind of a sense of mental time travel and 0:23:15.840 --> 0:23:18.200 so forth, but you also feel like you're there and 0:23:18.240 --> 0:23:21.560 you know, and you have a lot of those physiological 0:23:21.640 --> 0:23:26.560 sense of remembering, so to speak. And why that's important 0:23:26.600 --> 0:23:29.840 is that they are different from each other in that 0:23:30.520 --> 0:23:35.240 you can have a sense of remembering without that amygdalo component, 0:23:35.680 --> 0:23:38.159 and you can have that amigalo component giving you the 0:23:38.200 --> 0:23:43.320 physiological associations of a memory without actually remembering an event too. 0:23:43.480 --> 0:23:46.520 So they're different. But the interesting thing is people tend 0:23:46.560 --> 0:23:49.879 to feel like if they remember something and they have 0:23:49.960 --> 0:23:54.359 this big emotional response that they're somehow that memory becomes 0:23:54.400 --> 0:23:57.760 more vivid. So it's like they're two different things, but 0:23:57.880 --> 0:24:01.399 because they work together, they get you this integrated feeling 0:24:01.480 --> 0:24:02.160 of remembering. 0:24:03.400 --> 0:24:06.000 Let's take a quick break here, we'll be back before 0:24:06.040 --> 0:24:23.320 you know it. Welcome back. I'm here chatting with doctor 0:24:23.400 --> 0:24:27.240 Charon Ranganath about his book Why We Remember. Let's jump 0:24:27.280 --> 0:24:33.359 back into some questions. You write that to make memories 0:24:33.400 --> 0:24:38.000 that stand out, we need attention and intention. Can you 0:24:38.200 --> 0:24:40.600 give an example of what each of those is. 0:24:41.480 --> 0:24:45.119 Yes, So let me backtrack for just a second again 0:24:45.119 --> 0:24:49.679 to give the listeners some context, which is that imagine 0:24:50.000 --> 0:24:53.119 you have like a desk and it's just cluttered with 0:24:53.520 --> 0:24:56.160 all these like, uh, you know, I don't have to imagine, 0:24:56.160 --> 0:24:58.120 it's like I'm looking at what right in. 0:24:58.000 --> 0:24:58.600 Front of either. 0:24:59.119 --> 0:25:02.440 But but imagine that you just have your desk and 0:25:02.520 --> 0:25:04.960 it's cluttered with a bunch of junk, and it's all 0:25:05.160 --> 0:25:07.879 the same color, it all looks about the same and 0:25:07.920 --> 0:25:10.480 you're trying to find one posted note in this big, 0:25:10.520 --> 0:25:13.920 messy desk. It's going to be really hard. But now 0:25:14.119 --> 0:25:17.959 imagine you have like a fluorescent pink posted note sitting 0:25:18.080 --> 0:25:20.240 on this desk that has a bunch of white papers 0:25:20.280 --> 0:25:23.680 on it. It sticks out more, it's easier to find, right, 0:25:24.240 --> 0:25:26.800 And so memories are the same way. Because memories exist 0:25:26.840 --> 0:25:30.040 in this kind of ecosystem. It's not like there's just 0:25:30.119 --> 0:25:33.680 these individual memory traces. It's like the neurons are these 0:25:33.720 --> 0:25:38.159 different coalitions that are almost competing against each other. The 0:25:38.200 --> 0:25:41.920 science we call that interference. So the best way for 0:25:42.200 --> 0:25:45.200 a memory to be something that you can access very 0:25:45.240 --> 0:25:49.920 easily is for it to be distinctive. And the more 0:25:49.960 --> 0:25:52.720