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Tai Asks Why

Season 2 - Deja vu

VOICE: This is a CBC podcast.

TAI: You guys know that feeling, when you're in the middle of your day doing whatever, doing your normal thing or your unnormal thing, doing whatever, really and then just all of a sudden you just get this weird like epiphany feeling like, whoa, I've done this before.

[Music]

TAI: And, you know, you haven't, but you feel like you have. Déjà vu. Right? Which I learned from my papa that it comes from the French and it means already seen. So you feel like you've been in the situation before. You feel like. That's important thing, but you haven't cause it's happening right now. If you guys like it, that's great, but I think it's like a really weird sensation.

FINN: Deja vu is like, I know exactly what's coming next. This is really weird.

ZOE: Well, sometimes I just get this weird feeling.

KADEN: There's sort of nothing else like it.

ZOE: Like it happened to me this morning, actually. But sometimes it's stronger than other times.

TAI: But why? My friends had some theories.

ZOE: Maybe, you just dreamed about it. I don't really know. I have that feeling sometimes.

KADEN: But people think that it has something to do with like a parallel universe where pretty much you have memories from like another parallel universe where like you've already experienced that before or you're experiencing it simultaneously. So you feel like you've already experienced it.

PIPER: Sometimes I feel like when I have deja vu, it's like, oh, well, then this is actually meant to happen or something like that.

ZOE: I think maybe it's because your brain is really good at figuring out patterns. If you notice something is really similar, maybe that's your brain saying wait a second.

TAI: My friends had some good ideas, but, you know, which one is it? Is it a past life? Is it part of a dream? What's happening in your brain when you experience deja vu? Is it a good thing? Is it a bad thing? Why do we even have it in the first place?

[Tai theme song]

TAI: Hi there. I'm Tai and this is my podcast, Tai Asks Why. There are so many good questions out there. They just really want to get answered. How does a song get stuck in your head? When the dinosaurs died, why did some other animals survive? What are animals saying to each other? What is the science of bullying? Why is space so dark? And what is deja vu?

[Music]

CHRIS: I think the déjà vu is a is a memory problem.

TAI: This is Chris Moulin. He's a neuropsychologist at the University Grenoble Alps in France and he's an expert on memory and deja vu. So Chris, what exactly is deja vu?

CHRIS MOULIN: I think deja vu is is caused by like a little glitch in the memory system where you have two feelings at the same time. You have the feeling that you find something familiar. And at the same time, it's that you also know that that familiarity is false. In fact, it couldn't possibly be true.

TAI: For some reason you get the experience of remembering it while it's being stored in memory for the first time, so you get a feeling like like I've been here before. If you're like on the moon.

CHRIS MOULIN: Yeah, exactly. So you would have like the feeling that your your having a memory, but without actually having the memory. And the example of being on the moon is a great example cause we know that deja vu in fact happens more likely in in novel environment. So if you go to a place for a first time, it's then that you'll likely to get deja vu. So I went to New York for the first time in my life and it was a really big deal. And when I was there, I turned the corner and I had a massive sense of deja vu. I had this big feeling of familiarity, but I knew it was the first time I'd been in there New York, so it wasn't possible. I'd been there before. So it wasn't possible that it was a memory. It was a very strange experience.

TAI: Yeah. Did you like, hold on. Like, I swear I saw it before. But like, I guess I didn't. Is it still deja vu, if you like, if you feel the sense of familiarity, but you're not sure that you've been there before, you're like, oh, wait, hold on. I've been to New York before. Is that still deja vu?

CHRIS MOULIN: Well, that is such an excellent question. So one of the conundrums in deja vu, such as why old people get less deja vu. And I think just like you've kind of suggested they get less deja vu because they say, well, they've just done so much that it is it is quite possible they're confused because they did already do something very, very similar. And I don't think that is déjà vu, because I think deja vu is only that time when you're really certain it hasn't happened before and there's not that sort of confusion.

TAI: Yeah, that that does make sense.

[Music]

TAI: So according to Chris, déjà vu starts around the time you're 10 and it just gotta dies out after your 30s. So I'm in the height of my years. I've gotta get out there, take advantage of this sweet spot before the world gets too familiar. And you know what? I'm actually going in New York with my family for the first time next week. Who knows? Maybe I'll get a déjà vu.

[Music]

TAI: OK. So I'm here in New York, Manhattan specifically. Man, this place is massive, like it's really big. The buildings and the skyline. I really like how it's so organized, everything is just so big. But unfortunately, I'm not getting any deja vu yet, you know. Everything's completely new. Turns out I can't really force myself to get deja vu

CHRIS MARTIN: When it happens, it's really fleeting. It's hard to put your finger on it. It's almost over before you even recognize that it's even happened. It's also hard to predict when it will happen. So it makes it really challenging to study in the laboratory.

TAI: This is also Chris, Chris Martin, not Moulin. He's a postdoctorate fellow working at the psychology department at the University of Toronto. And just like other Chris, he spent a lot of time studying déjà vu. And he explains that even though it's really hard to know when it's going to happen, there are actually ways that we can study it.

CHRIS MARTIN: What we can do is look at populations that have it in the context of temporal lobe epilepsy, which is a particular type of epilepsy. A little more than half of those patients experience deja vu with their seizures.

TAI: So Chris explained that the way they figure this stuff out is that when people are having seizures, whatever they experience helps give us clues about where in the brain the seizures are. So if you start seeing weird dots and colors and shapes, when you have a seizure, then they're able to figure out that it's probably happening around the part of your brain that deals with vision. And when people have déjà vu with their seizures, it's probably because it's happening in the part of the brain that deals with memory. But is the deja vu that they get with their seizures the same as the deja vu that I get?

CHRIS MARTIN: They're not radically different than what you or I would describe. It might last longer. So sometimes they could last up to a full minute versus what we might experience being two, three, four, five seconds, something like that.

TAI: It's a nifty feeling, but I guess if it happens for longer periods of time, it could be like really scary. Like, what's going on? Everything is happened before.

CHRIS MARTIN: Yup, and actually. So one neat anecdote I can share with you is this patient, I'm thinking in particular is said, you know, I'm looking around to find something that isn't familiar, but everything seems to be familiar, even though I know it shouldn't be.

[Music]

TAI: OK. So to learn more about what's happening in the brain when these deja's are vuing, Chris Martin brings epileptic patients to his lab to check out their brain activity. So I got him to take me to his lab to check out what deja vu looks like in the brain. Its all right.

CHRIS MARTIN: We are in Sydney Smith Hall at University of Toronto. The psychology department and most of our labs are downstairs, which is where the lab that I work in is so we're heading down there.

TAI: So this is where he takes patients that are part of their experiments. It's really cool. How are we able to understand what goes on with déjà vu? How are you able to capture what's going on in the brain?

CHRIS MARTIN: So one way to do this is implant electrodes that would go deep into the brain and have multiple recording sites on those electrodes so they can really localize of a high degrees of precision where in the brain these seizures are starting. And what's really interesting about these depth electrodes is that you can also use them to stimulate the brain.

TAI: Wow, that's gnarly. So Chris can apply these electrical impulses to the brain through these sites and see what sort of experience the patient has and what they've seen is that the seizures are starting in these specific parts of the brain called the paver rhino and enter Ronald Cortex. Rhinel means nose. So parrot rhino means near your nose and end to rhino means in your nose. So you can try to picture this weird deja vu area inside your head where your nose ends and your brain begins.

CHRIS MARTIN: And what's most compelling is if you stimulate those regions, the participants have these sort of fleeting experiences of familiarity. They wouldn't know that you've just stimulated they just spontaneously say, I'm experiencing deja vu right now.

[Music]

TAI: So you guys do have ways to induce déjà vu.

CHRIS MARTIN: There are ways in clinical settings to induce deja vu. Yes. You can connect the dots and say, well, if we stimulate here, we see deja vu. If we stimulate elsewhere, we don't see that response.

TAI: So you say that you have pictures. What do those look like?

CHRIS MARTIN: Oh, yeah. They look like brains. Sorry. So I just thought I'd give you a sense of of where in the brain we're talking about.

TAI: Best part of the job, kids.

CHRIS MARTIN: So these are, in fact, pictures from inside your brain, not your brain, but inside of a brain. Inside someone's skull.

TAI: OK. It looks like I have no interpretation cause it has nothing that I could relate it to.

CHRIS M: Yeah, it looks a little bit like cauliflower. This is looking at it from the front as if you're coming in through some of the face or the back of the head and just scroll through any one of these and you can.

TAI: Whoaah

CHRIS MARTIN: Hold it through the entire brain.

TAI: Wow.

CHRIS MARTIN: So it's this purple part of the brain that if you stimulate you, you may experience deja vu.

TAI: I can see deja vu. OK, guys. It really does look like a weird, complex, slightly moldy cauliflower with all the grooves in the branches. It's really cool that Chris can just pinpoint these exact locations where déjà vu occurs.

CHRIS MARTIN: The other thing you can do in the context of epilepsy is look at long term consequences of these repeated seizures. So what we find is that we see reduced volume in patients who have deja vu as compared to those who don't in these very specific regions.

[Music]

TAI: Woah, so the epilepsy patients who have deja vu, who have these regions in their brains that are smaller than those who don't. It's really weird and I don't have epilepsy or anything, but I do get deja vu. So is it perfectly fine in part of a healthy brain or is it shrinking my brain sponge? Is it bad? Like, is it not good or is it just kind of just like a byproduct kind of just what happens? Because we see that it links to the reduction in size. But we don't necessarily know that that's the cause of the reduction. So is it necessarily bad?

CHRIS MARTIN: So anytime you have a seizure, that's bad. But I don't think that deja vu is necessarily bad. In fact, I think it's evidence of a healthy working, good working memory system because it's an indication that everything's going right and that you can detect that conflict.

[Music]

TAI: I asked Chris Moulin about this too remember him from earlier?

CHRIS MOULIN: I think deja vu is is caused by like a little glitch, glitch in the memory system.

TAI: Two Chris's. It's kind of like deja vu, right? Anyway, Chris Moulin agrees with Chris Martin that déjà vu isn't bad for us. Two Chris's. Two different last names. One result. So if they both say that it's not bad for me, then I'm going to assume that it's that the Chris's aren't lying and déjà vu isn't shrinking my brain's bunch.

CHRIS MARTIN: No, I don't think déjà vu is a bad thing at all, I think it's a sign that something's going on that's healthy. It's like a check saying, hey, hang on a minute. No, no, no no no

TAI: Oh, so, my friend Zoe was right.

ZOE: Maybe that's your brain saying, wait a second.

CHRIS MOULIN: So it's something that checks the familiarities system, doesn't run away with itself, that things don't get too familiar or that you have strange sensations of familiarity when when you shouldn't. I think it's something that's uniquely human in that sense, that it's this higher order consciousness we can have about thought processes.

TAI: Yeah, if your brains get to slip up every once in a while, it's best that you're aware that it's doing this.

CHRIS MOULIN: Absolutely. And more than that, most people describe it as quite a pleasant experience. I don't know if you like it when you've had it.

TAI: It's a good thing at a bad thing because for the first five minutes you're like, well, it's like really weird. You're kind of like creeped out. But for the five minutes after that, you're going to like, well, more like, whoa, like, you know, like, well, that was those cool. Cause it's like creepy but not like makes you unnerved.

CHRIS MOULIN: It's like weird. But it doesn't really scare you. It's like ohhh.

TAI: And then for the next couple of days, you're just like, well, that was that was cool.

CHRIS MOULIN: Yes. It makes you sit up and think, hey, what's what's going on? How does my mind do this to me? Ooh.

TAI: Woah.

CHRIS MOULIN: Ohh

TAI: Well, that was that was cool.

CHRIS MOULIN: So I don't think it's a bad thing. I think some people get it at times of stress and some people can have like kind of pathological forms of it, but I don't think it's a bad thing when we experience it.

TAI: OK. For those of you who don't know what pathological means, it means something related to a disease. Pretty much. So for the people with epilepsy getting deja vu, that cancer is a pathological kind of deja vu. But Chris says he's seen other weird bad types of deja vu too.

CHRIS MOULIN: Just after completing my PhD When I worked in a memory clinic, there was a guy who came in and his complaint was unusual. And he complained that he had already been tested before in the memory clinic. And his wife said that that was his problem. Instead of being forgetful, he complained that everything was a repeat of something he'd already done.

TAI: So what's that like? What happens if you get really frequent deja vu?

CHRIS MOULIN: It's a sad thing, really, because the people I've worked with who do have very constant forms of déjà vu like this patient I was talking about, the first guy I started working with, they become withdrawn and depressed because just as you say, they can't find anything new. And if you think about your life, what motivates you? And a lot of the good stuff is the new stuff. You don't want to watch the last episode of your favorite show. You want to watch the new episode. So we see that the people like that, they do kind of get a bit difficult to motivate and to find interesting things just because they they feel that everything's everything's repeating. You begin to understand when you work with rare disorders like that how the memory system is constantly active, like you are constantly looking at everything in your environment to see whether it's familiar or not, whether it's something you already encountered or not. And thankfully, it all goes on automatically without you ever really thinking about it until you have something like a deja vu. But the deja vu there shows you just how that automatic process is always going on.

[Music]

TAI: So your memories constantly accumilating all your experiences trying to see what has helpful info for the future. And this process just keeps on going, keeps on going behind your nose and that brain area that Chris Martin showed me. And you know, it's a good thing cause if everything was super familiar all the time, I'd be really sad cause, you know, movies would just suck. Nothing would be new and exciting. I'd be really sad. And the opposite would be kind of bad, too. Like if nothing was familiar, I wouldn't remember my route to school, how to tie my shoes. I wouldn't remember the answers for a test I was studying for. So I'm glad I got this weird déjà vu glitch. Checking in on me cause it helps me make sure the world is just the right amount of familiar. And it turns out there's other helpful glitches we get too.

CHRIS MOULIN: I mean, have you had this sensation where you look at a word for a long, long time and it starts to look strange like it might be spelt wrong? Or did you like sometimes go to write a word and then think, hang on a minute. Is it spelled like that? No, that looks completely weird. Did you ever have that?

TAI: Yes.

CHRIS MOULIN: So thatm that is related to deja vu. And that's that's, you can think of that as the opposite of déjà vu. That's called jamais vu.

TAI: In French, of course. My papa, who's great at French, tells me that jamais means never seen. So it's like the opposite of deja vu. Already seen just never seen. Mon francais tres bon. Oui oui oui. Merci papa

CHRIS MOULIN: And again, we can think of it as the same kind of a control mechanism but work in the other sense so that you don't want things to get so familiar. Like imagine if you if you like, just kept repeating stuff and repeating stuff and you never had any check on on whether it was right or not.

TAI: Yeah, I play piano, so like every time you're doing a song and if it's like three or more pages, every once in awhile, it'll just kind of be muscle memory. And then when you actually think about it, you just like stumble over your hands and then your hands just like you're like, what? Cause the more you think about how you play, you just like completely fall apart.

CHRIS MOULIN: Yeah. Exactly. I had it once when I was driving. And all of a sudden I was like oh my goodness What are those pedals for. I don't remember which pedals which.

TAI: Yeah. That is that's that's bad. OK, so then what is deja vu tell us about memory itself. You know, cause it's like it's a little unnerving that our brain does have these glitches.

CHRIS MOULIN: Yeah. I mean, I think I think you're right. It makes me sometimes question how would I ever know if something I'm remembering is a real memory or not? And in fact, there's plenty of evidence, not just for deja vu to make you think that. Hang on. Memory isn't that reliable. It has its biases. And we tend to confuse very, very similar events and similar people and similar objects. So one of the things that deja vu really rams home is that kind of idea that memory is kind of constructive and you make up a memory. But not only that, the thing that deja vu tells you is that what makes a memory is that it feels like a memory. And sometimes you can have that feeling even when it's false. So if you didn't have deja vu and if you didn't have this fact checking mechanism, then you'd be in real trouble cause you'd never know whether what you were remembering was a real memory or not.

[Music]

TAI: Pwow. That was just my mind exploding, that was really awesome.

CHRIS: And I must say you're pretty awesome, too.

[Music]

TAI: So I see what Chris is getting at. Memories are just assumptions you assume that this happened and this happened at this time. And if my memories, these assumptions are subjective. Then there's no real objective perception like myself, my life. It's all based on these assumptions of what are my memories. They're all just things I just thought was right. But there is a real world out there. Maybe that's why we get deja vu in new places because the mind just kind of has to dodge this is their big wide world. It's either been there or haven't. And you know, whether or not it's happened before is déjà vu. Double checking these assumptions. I wonder what my friends would think of all my new deja vu insights. So how do you guys take to the idea that déjà vu might just be your brain double checking your memories? If you're like I've been here before. Your brain is just helping you snap out of it and realizing you're not.

KADEN: Yeah, that's that's interesting. But it also makes a lot of sense.

FINN: I kind of imagine the brain as a computer like wires can cross and it's not predictable.

ZOE: Brains are weird.

TAI: Woah.

VOICE: Woah

[Deja vu song]

TAI: Deja vu. Deja vu. Deja vu. This feels familiar. I've been here before. This feels familiar. I've been here before. Deja vu.

TAI: Thank you so much for listening. I'm Tai Pool. This show is produced by Veronica Simmonds and Amanda Buckiewicz. Today my guests were Chris Moulin, Chris Martin and special thanks to Tina Verma, Sonya Buyting and my friends: Finn, Piper, Kaden and Zoe for talking to me about deja vu. The theme music is by Johnny Spence. And another big thanks to Johnny for helping me write and record the Deja Vu song.

VOICE 1: Next time on Tai Asks Why, bullies.

VOICE 2: Bullying is probably ubiquitous amongst life itself.

[Music]

Tai: Till next time. I'm Tai. Keep asking why.

VOICE: For more CBC podcasts, go to cbc.ca/podcasts

TRANSCRIPT: Tai Asks Why - Season 2: Deja vu

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