Hippocampus Love: The Neural Representation Debate & Cognitive Maps with Lynn Nadel (BONUS EPISODE)

 Decoding the Brain: Representation and Relational Memory in Cognitive Neuroscience
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This episode of 'Love and Philosophy Beyond Dichotomy,' hosted by Andrea Hiott, features a deep dive with Lynn Nadel into the complexities of representation in the brain. The discussion explores how thoughts and memories are formed and represented, beginning with a child's understanding and extending to advanced theories in neuroscience. Central themes include population coding, the relational nature of brain functions, and the embodied cognition approach. They also touch on historical perspectives from key figures like Tolman and Eichenbaum, the idea of cognitive maps in the hippocampus, and the role of pre-wiring and experience in shaping brain functions. The episode highlights ongoing debates and innovations in understanding cognitive processes and how the brain models reality.

Slides are here

Full conversations (1-5) with Andrea and Lynn

00:00 Introduction to Thought and Representation
01:48 Exploring the Concept of Representation
04:07 The Hippocampus and Cognitive Mapping
08:50 The Mind-Body Problem and Cognitive Neuroscience
29:30 Topographic Maps and Brain Representation
32:21 Understanding the Somatic Brain
32:50 Face Systems and Brain Localization
33:26 Sensory and Motor Systems
34:21 Mapping the Brain and Body Connection
35:01 Historical Insights: Penfield and Milner
35:50 Topographic Maps and Computational Advantages
38:11 Hippocampus and Non-Topographical Maps
39:44 Representation and Meaning in the Brain
48:20 Associative Learning and Memory
01:00:31 Concluding Thoughts and Future Discussions

Lynn is in Trondheim during this discussion attending the Kavli Prize week. This is the third conversation with Andrea and Lynn.
Exploring the Cognitive Neuroscience of Representation: Past, Present, and Future
#representation #lynnnadel #neuroscience #hippocampus #representationdebate

A Research Discussion with Lynn Nadel, part Three. 

In this (talk three) Andrea & Lynn discuss how we have thoughts and memories and what this means a la representation.
First talk
Second talk

Radical paper from Andrea

Transcript

Lynn Nadel: [00:00:00] There's no world out there, right? I mean, it's all constructed in our head. Basically, you ask, if you ask a five or a 6-year-old, which I've done this with my grandkid, and you know, you, you ask them, you know, where did their thoughts come from? Where they, you know, it's in, they point in here, 

Andrea Hiott: how can this physical body or this brain give rise to that sense that even your five-year-old grandchild has of self?

Right? Right. It's, it feels very mysterious. It is very wonderful. 

Lynn Nadel: Right. Words are. Really good. They're better than grunts and, but you know, they still don't quite capture the nature of what it is, of thought. So thought goes beyond language, I guess, is the, is seems clear. 

Andrea Hiott: This is like the little movie playing in our heads, obviously.

Right, 

Lynn Nadel: right. You know, we have a picture on the retina and we have this writing, it is this movie playing basically. And, and that's how we represent the world. And of course that's complete nonsense because, Who's watching the movie, I mean, who's, who or what is doing the decoding, I mean, there are some people who would argue that, [00:01:00] you know, there isn't a decoder. It's all just a continuous loop between the environment and the, and the brain. Basically, again, it comes to the issue of where's the decoder for that, for that, for that population, and what, how, how do we connect up the, the, the population story, which is what everyone talks about now to, to this issue.

Higher level issue of representation yet, but the pre-wiring in the system at this porus kind of mm-hmm, mm-hmm. You know, reflects the manifold of, of the cells that are available and it's already there by day 10. So what that tells me, and I think what it tells the Moses as well, is that some aspects of the way we represent the world are the whole grain is a relational device.

Everything the brain does is relational.

 Hi everyone. This is Andrea Hiott. You're listening to Love and Philosophy Beyond Dichotomy. This is a special hippocampus love episode with Lynn Adele. If you've [00:02:00] been following the research channel on YouTube or elsewhere, you've probably heard a few talks between Lynn and I. There have been, I guess, three public ones now.

Fourth one, I'm gonna publish soon. This was the. Gosh, I don't know if this was the second or the third talk. Anyway, this one is about representations. I haven't posted it as an audio podcast, so I wanted to go ahead and do that as a bonus. I also wanted to do it because I had a paper come out recently, which is about radical relation, and it's about representations in the hippocampus.

And a lot of these ideas, and Lynn and I just did another talk together about a paper that's related to that. And I'm also going to be posting a piece where I try to explain that paper and also this idea of. Cognition being a form of navigation, navigation being a form of cognition. And by the way, I'm not saying either of those things, um, [00:03:00] although it does get confused as if I'm saying one or the other of those I'm not.

However, I am saying that they're the same process and I'm saying something actually much more radical than you imagine if you try to dismiss it as, oh yeah. Mind is like moving through a landscape, but you'll just have to watch the other video to really understand that because it's hard to explain.

It's all about holding paradox, exploring beyond dichotomy and everything else that you've ever heard on any podcast here, because this is one huge document that I'm putting together that goes along with the book that's coming out next year, but also my thesis and. Quite a few other things that are in the works, so it'll all become clear at some point.

If you actually care about all of this, you can put the puzzle together. It's actually a big jigsaw puzzle, which you can put together if you really want to. If you wanna look at every. [00:04:00] Video and listen to every podcast and look at it through this document. Uh, you'll see that it kind of unfurls in a fractal way.

But in any case, a big part of this is Linda Nadel, John O'Keefe, the hippocampus as a cognitive map, and, um, Edward Tolman, all these people that. It have to do with hippocampus research, which is just so important to me, and I'm just so grateful for them. And I love being able to talk to Lynn, whose story I tell in part in the book that's coming out next year.

But also just all his research and his thinking and his collaborations. And he was in Heim, I think it's a year ago we had this conversation. He was giving some lectures in the Moser lab. Which he was doing again this year, and we had another talk, but this one is from a year ago, and they were also having the big neuroscience awards there at the time, which I think he talks about.

So this is about representations in the brain. There's [00:05:00] this problem if you don't follow neuroscience, but this idea of what a representation is, just to put it in really general terms, when you have a thought, where is that thought? Is it a little form in your head? How do you find it? So we talk about that and it's of course much more complicated than that.

But in a way, it's also just that we just wanna know what a thought is and how to find it and what a memory is and where it is, and if that is even a question that makes sense. Frankly, when we think about this whole process that we're studying, Lynn and I talk about that. We kind of break apart this idea of representation in the brain.

We look back at this really old. class he taught, on representation. And if you wanna see the slides for that, there is a link in the show notes and you can download them. But just remember they're like 10 years old. but still they, they're about a lot of topics that people still talk about. We talk about cognitive maps and different brain parts and their functions and how all this kind of can work, and this coding and decoding and these words all mean special [00:06:00] things.

But it'll just make sense on a general level too, if you listen to it. We do talk about population coding and topographic maps and other sorts of brain activities, but if you don't know what all that means, you can. Ask Claude or someone, or you can just skip over it, because it's really just a conversation trying to figure out some basic ideas about what's going on.

How can we remember? How can we think? Why is it that even a 5-year-old understands this process and somehow has come to imagine that it's happening? In the brain. I think it's happening in the whole body and that half the reason kids think that is because we tell them it's happening in their head. But anyway, that's a whole other conversation.

You'll hear Lynn and I talk about that a bit. Mostly we're just talking about the mysteries of what it is to have memory and be alive and wow, isn't that exciting? I think it's just endlessly fascinating and wonderful that we're here. [00:07:00] Although of course it's also hard and challenging, but let's leave it on a positive note today.

And here's Lin Nadel. I highly suggest you check out his papers if you're interested in learning more about the hippocampus. I'm sorry my voice is almost gone. but I leave you with a big hug today and a hippocampus.

Lynn Nadel: And, uh, you know, I'm, I'm, I'm going to give a talk, uh, next week, probably on the, you know, sort of the early history of work on the hippocampus, kind of the background to the emergence of the cognitive math theory, kind of what the field was like in the fifties and sixties and seventies. And, you know, how, how it all came about, you know, how, from my perspective, you know, all the pieces came together, so to speak, historically.

you know, Edvard said, you know, the students here, they don't know anything that happened before more than like 10 years ago, he said. 

Andrea Hiott: It's a long time ago when you're 20.

Lynn Nadel: Yeah. So last year, yeah, right. So last year I gave, you know, three, three research talks here [00:08:00] of one sort or another. This year, I, I don't have oh 

Andrea Hiott: three in one year. You were there that much last year? 

Lynn Nadel: I, no, one month. I gave three over the course of Oh. Oh. In one? No, no. I think I gave two. It doesn't matter. I gave a couple of, yeah, you gave a bunch.

I gave my research talks this year. I don't have anything new to say about research specifically that I wanted to talk about. So this is, this is gonna be my, my presentation while I'm here is a, a history talk, which I'm working kind of fun putting the pieces together and trying to, trying to reconstruct the causal.

The causal chain, you know, gosh, 

Andrea Hiott: I'd like to at least read that if you don't publish it somewhere because that's, that's probably very interesting to see how you put that together. 

Lynn Nadel: Yeah. Well, so much of it flowed through Montreal and you know, 

Andrea Hiott: we talked about it. 

Lynn Nadel: Yeah. Yeah. Right. Exactly. 

Andrea Hiott: Yeah. 

Lynn Nadel: This is the history that I've been talking to you about anyway.

So 

Andrea Hiott: speaking of history today, we're going to try to talk about this really difficult word, representation, dare I even say it, but, um, Yeah. [00:09:00] In terms of cognitive neuroscience though. So for all the people who might be thinking we mean it in other ways, because you can talk about representation in so many different ways, whether you're in art or philosophy or whatever, but we're going to talk about a little bit philosophically, I think, but mostly through sort of cognitive, Yeah, science, right?

So I guess I was gonna I was thinking today I just kind of play like the student instead of trying to Pretend like I really understand all this because I was looking at your um your class, which I was just trying to find but Yeah, in any case, there's a class you taught like a long time ago, right?

A couple 

Lynn Nadel: Yeah, it's like 10 years ago I gave that, you know. Most of the stuff that's in there, you know, hasn't changed. 

Andrea Hiott: And even some of it I realized had become kind of popular again, when Well, we'll get to questioning certain aspects of what is representation and you need a perceiver to see the representation, right?

In any case, before we get into all that, let's start with just cognitive neuroscience like you do, because it's really interesting, right? And I think for people who are trying [00:10:00] to follow this, like, why do we focus so much on the brain? And I think in those notes, you kind of start with it's, it's been that way forever, right?

What are we, why are we trying to provide a brain based account of, of cognition. Um, I mean, is it really just like simple? we just feel like we're in our heads because all our sensory organs are so located there, you know? 

Lynn Nadel: Yeah. I mean, if you were, I mean, if you took, if you were to take a kind of a, a Barkley stance and John actually did this at the dinner, he was being somewhat of strappers and he said, you know, there's no world out there, right?

I mean, it's all constructed in our head basically. And so, I mean, if you take that kind of a position, I mean, it's all inside our head and we were We're creating this whole external world, you know, which may or may not match up to what's actually out there. I mean, who knows? Uh, it better match reasonably well.

Otherwise evolution would have squashed us. But yeah. So, I mean, it's inevitable that, you know, you think about, you know, how is it that we understand and comprehend the [00:11:00] world so that we can behave so that, you know, our, so that our behavior, which whatever one thinks about the notion of representation.

It's hard to, it's hard to say that the brain has nothing to do with behavior. Right? I mean, it's got, it's what makes us move. You go back to movement. Right? So, I mean, we move because our brain, you know, tells us to move and we move the ways 

Andrea Hiott: But we also have a body and we, I mean, it's not disconnected from the body.

So I guess it's just like you move into the mind body problem, but it's just this feeling we have, right? Of our experience of the world feels like in our head. Doesn't it? Yeah. Absolutely. 

Lynn Nadel: Yeah. We can't get away from that, it seems to me, no matter how, no matter what philosophical position we take.

So, so with that, you know, as a, as a starting point, you know, you have, you have to think about, well, how, how does it come to be that the brain models, let's use that term, you know, represents. you know, the outside world in a useful way, you know, so that it can [00:12:00] guide, you know, guide our behavior going forward.

There's really no, it doesn't seem like there's any alternative to that position, so it's not. You know, people think about, well, so what, what is, how does the brain represent the world? How does it, how does it do that? You know, there's no other way to, there's no other way to think about, you know, strikes me as a scientist.

There's no other way to think about behavior. 

Andrea Hiott: Yeah. So if we just think of people coming to a kind of awareness of themselves, then you have this feeling like you're sort of in your head and the representation there in that really early sense is just that, , It's almost like we, we can sort of have these images of ourselves or we can sort of hear our thoughts, right?

And so that feels like it's some kind of, we're representing the world in our heads, right? In a very simplistic way. 

Lynn Nadel: You ask, if you ask a five or a six year old, which I've done this with my grand kid. And you know, you ask them, you know, where their thoughts come from, , where they, you know, it's They point in here, , it's not, mean, they, they understand, [00:13:00] you know, it's, it feels that way. It's exactly as you say. so we, I mean, what there's. Okay. I mean, I can leave it at that, except to say that there's, you know, there's a couple of different facets of this representation problem. I mean, One of them is how does it do it, you know, and how does it, you know, how, how do we represent the world and how are those representations used, all the kind of mechanistic questions about it.

But then there's the more complex question which I don't think I certainly haven't made any progress on, which is, You know, why does a particular kind of brain activity represent a particular thing? I mean, why is it that, you know, activity and visual neurons in the visual system actually represent visual phenomena?

I mean, it's, it's that it's the kind of the heart, it's the consciousness heart problem, but it isn't just about consciousness. It's simply how come certain forms of activity represent certain things? Kind of. [00:14:00] That's the deep question, you know, for me. 

Andrea Hiott: Yeah, well, I just I think it's it's like we all have this fascination with becoming aware that of our own thoughts in a way And then they don't feel physical, right?

Lynn Nadel: Absolutely. They don't feel 

Andrea Hiott: that's a very we're physical and we're experiencing them physically But from that vantage point it feels like something not as physical as for example, just to touch the table Right. So your little five year old, grandchild, you know, it's kind of 

Lynn Nadel: feeling about it.

Andrea Hiott: Yeah. And, 

but so there's this mind body problem of how can this happen, right? How can this physical body or this brain give rise to that sense that even your five year old grandchild has of self, right? Right. It feels very mysterious. It is very wonderful, right? Yeah, it is. Mind, is it consciousness?

All these words we use in so many weird ways, But when it comes to trying to study the brain, actually thinking [00:15:00] about what is reality, so to speak, if if we just, I think, I don't know how you feel about this, but I think it's a very bodily experience of cognition and representing the world.

Of course, the brain is paramount, but let's just say we're going to focus on the brain and how this mental experience arises, what the brain's role is in it. And then we bring in this world represents. So what we're trying to understand is different kinds of reality. Isn't that how you say it in your talk?

Like, there's a kind of current reality right now where I'm having thoughts. And then there's this thing we call memory, which is the fact that I know there was a reality yesterday, or that you were in the States recently, now you're in Norway, and all of this. And then there's the future, What you talk about.

Right. Right. Prediction. The brain 

Lynn Nadel: can do all of that. You know, and, and, but, but of course, mostly we get to describe what we're thinking about in words. But we know for, from a variety of perspectives that the words we end up using separate from words or form of behavior, of course, but a very specific form [00:16:00] of behavior, they never quite capture what it is we're thinking about.

I mean, you know, we get as close as we can, but, you know, any Anyone who's kind of thought introspectively or tried to think deeply introspectively knows that they have some thoughts, and they're never quite successful, they're never 100 percent successful in getting exactly what it was they were thinking into words.

Words are really good, they're better than grunts and, and, and so 

Andrea Hiott: on. 

Lynn Nadel: But, you know, they still don't quite capture the nature of what it is. Of thought. So, thought goes beyond language, I guess, is the, is, seems clear. There's good evidence for this. I've actually, Nancy Kanwisher talked about this in their, in their Kavli talks. There's pretty clear evidence that, you know, that you can just, you can separate out language from thought. I mean, many thought, a lot of thought is language, but not all of it.

So, So, [00:17:00] you know, that means there's some deeper, so the representations that we have in the brain are not just words, there's no kind of lingua franca, there's no fedorian, what's the language of thought then? It's not words. So, the language of thought has something to do with this issue of representations.

Anyway, I mean, I think the data certainly from, uh, data suggests that the two are not totally identical.

overlap. And that again, just points to the, you know, there's some, somehow the brain is representing information in a way that is useful, that you can use to generate language that you can, that you use to generate behavior, and it must match the world, you know, close enough so that, you know, you survive in the world and the species survives.

So, and, and, uh, so how does it do that? That's, that's kind of the core question. You know, what's, you know, and the, so the earliest default was, well, let's look at [00:18:00] vision, you know, you say, okay, we know that the, an image of what's out there in the world, you know, is kind of reflected upside down in the retina.

Well, okay, that's it. Problem solved.

It's just like 

Andrea Hiott: a little movie playing in our heads. We have a 

Lynn Nadel: picture on the retina, and we have this, right, and it's this movie playing basically, and that's how we represent the world, and of course that's complete nonsense because, you know, who's watching the movie, right? 

Andrea Hiott: You have this infinite regress of a little person in your head watching 

Lynn Nadel: multiple 

Andrea Hiott: screens.

Lynn Nadel: But of course people thought that for a long time. It's They actually thought, you know, that that was a plausible story. Basically. Because that's how 

Andrea Hiott: it feels, again, you know, back to the five year old experience, that's how it feels. 

Lynn Nadel: And, and that's one of the reasons why for decades, maybe a century, people were all twisted up about the, uh, about the fact [00:19:00] that the image is inverted on the retina.

It was like, wow, this is a serious problem. How does the, you know, how do we deal with the fact? Are we 

Andrea Hiott: watching everything upside down all the time? 

Lynn Nadel: Like if, you know, and, you know, you can find hundreds of papers probably, you know, written trying to, you know, address this, you know, the really hard problem of the, of the inverted retinal image and how the hell does the, you know, does the brain solve it?

It's completely meaningless, of course, because there's nobody inside looking at the, at the image on the retina. It's got nothing to do with it. Yeah, but we 

Andrea Hiott: just take that for granted in a weird way. Yeah, 

Lynn Nadel: yeah. For so 

Andrea Hiott: long. 

Lynn Nadel: So that picture in the head kind of story that, you know, that you, I think that was called an eidola or simulacrum.

I mean, there were words that people put, you know, that you just, the brain just creates a replica of what's out in the world inside your head. But it, but it completely in the end becomes pointless because this default, you know, to the homunculus, you can't get away from it. That problem doesn't go away, by the way, no matter [00:20:00] what theory you have, there's always a problem of a decoder.

I mean, who's, who or what is doing the decoding? If any, if anything, I mean, there are some people who would argue that, you know, there isn't a decoder. It's all just a continuous loop between the environment and the, and the brain, basically. You know what I mean? And there isn't a single decoder, it's all just connected to, it's this kind of, that's the embodied cognition approach, essentially, where everything you do is 

Andrea Hiott: immediate sort of 

Lynn Nadel: coupling to the, and there's immediate coupling and you don't have to think about a decoder because it's all part of a, And, you know, by the way, that may not, that may turn out to be a pretty good story in the 

Andrea Hiott: end.

Yeah, yeah. I think it's part of trying to figure it out, but it's also, that's kind of the question of representation in a weird way too, is, because, as you say, I think in those slides, or you've said in other work, you know, like, we often do that same, make that same mistake that people were making for so long of thinking there's someone in the head, but we forget that we're the [00:21:00] scientists looking at.

The data that we've just gotten from the bet brain. So we forget that we're decoding it. Somehow that step gets like taken out. Right. So it's, it must be in the brain in the same way. It's in this little image of a, of a screenshot or something that we've taken. Like, Oh, it's, but that gets confusing too.

Doesn't it? That. The fMRI or the, or whatever we're looking at isn't actually in the head like that. 

Lynn Nadel: Exactly right. I mean, so we as experimenters looking at, you know, unit recordings or fMRI or, you know, multi unit recordings or these calcium or whatever, whatever we're looking at, you know, and we, and we connect up certain patterns of activity in the brain to certain behaviors, right?

We just assume that those patterns. You know, we see those patterns and we see the fact that they're connected to these things. Inside the head, how does that happen, basically? I mean, [00:22:00] the inside part of the head is not looking at the data the same way we are. We're seeing all the data, 

Andrea Hiott: right? 

Lynn Nadel: Any given part of the brain is seeing only a fraction of the data, so to speak, that we can look at as experimenters.

We jump to conclusions as experimenters, Oh, well, you see this pattern of place cells firing at me, as you know, such and such. Well, you know, is there any part of the brain that actually conceived that pattern of place cell firing in the same way we can see it and use it in the way that we think it's being used?

Or not, uh, probably, so 

Andrea Hiott: not, I mean, even using language to talk about it is weird because of course they can't, like, observe it in the way that we do with our senses or something. Right, right. Maybe there's some kind of pattern sensitivity or something. I don't know. 

Lynn Nadel: What's happening, I mean, what's happening now, it seems, I mean, all the, that lecture kind of brought, ended at the point where.

Right. People were saying, well, look what [00:23:00] the brain obviously represents information in some sort of a distributed code, a population code, that's that is generally, you know, accepted, there may be, you know, rather unique exceptions where a particular cluster of cells, you know, has a very unique function.

And you can say a small number of cells, you know, do the whole job, but mostly it's vast arrays of neurons in some population. what do we do with that? At this point, I mean, again, it comes to the issue, where's the decoder for that, for that, for that population and what, how do we connect up the population story, which is what everyone talks about now to this issue of this higher level issue of representation.

Right. And that's what's happened in the last 10 years so all the stuff that I didn't, you know that I now think I'm just not expert enough about, but which I hear a lot about here. Right. And which I heard about in the Kavli talks, especially Dara Sal, uh, you know, [00:24:00] it's about this. It's about the kind of structure of those, of that population of the, and, you know, people talking about the geometry of the, of the structure of that population and the possible.

Yeah. Et cetera, et cetera. And that's kind of where the field is headed now. And that's outside my zone of comfort. That's why I said I don't know that I have a lot more to add now, because I'm, I'm not sufficiently, uh, I'm not, I would say not sufficiently sophisticated, but I could say I'm not at all sophisticated mathematically to understand, you know, the kind of stuff that is being done now that points out the kind of consistent geometric, uh, and these are not, this is not clustering or topography in the way that one sees in the visual system.

This is simply. The kind of possible states that this multi vectorial kind of collection of cells can take, you know, that somehow serve as the [00:25:00] way it represents, say, an object or something. Kenneth Harris was here just the other day. He gave a talk on what you, what I would say was like representations in the visual cortex, and it was all about, you know, the, the population code and the bottom line of what he was saying was that If you, that the, the excitatory neurons, the population code in the excitatory neurons is very high dimensional and captures the specific features of the sensory input of the visual input.

The population code of the inhibitory cells is low dimensional. and reflects kind of the context, you know, or the modulation of, of, and those two things kind of playing off each other, basically, you know, you, you might want to check out Kenneth Harris's work on this stuff. It's really, 

Andrea Hiott: he's 

Lynn Nadel: at UCL. uh, so, [00:26:00] you know, and the folks here in Trondheim are on all are kind of very much on the issue of this, the Taurus that, you know, the, the manifolds So, as I understand it, a manifold is a kind of, is all of the possible states that a representation can take.

Let's say in the grid cell population, you know, the, the, there's a, there's, there are constraints on the, on where in the state space that population can be, right? It can't be everywhere. It can only be on this Taurus, because of the nature of the, of the, of the, and the Taurus, you know, which kind of constrains the possible states the Population Code can take, i.

e., you know, how it can represent whatever it's representing, that shows up, what they're showing here now, is that that shows up by day 9 or 10 in the RATPOS, before they're moving around in the world, before they've seen anything, their eyes are still You mean, they 

Andrea Hiott: haven't explored? There's been [00:27:00] no 

Lynn Nadel: They've had 

Andrea Hiott: no 

Lynn Nadel: experience.

Yet, but the pre wiring in the system. 

Andrea Hiott: Mm 

Lynn Nadel: hmm at this Taurus kind of, you know, Sort of reflects the manifold of of the cells that are available and it's already there by day 10 So so what that tells me and I think what it tells the Mosers as well Is that some aspects of the way we represent the world are?

are given, so to speak, prior to specific experience. Although specific experiences can subsequently influence the way this thing works, the kind of really pure Kant, you might say, the Kantian, the built in structure, you know, constrains the representation. And, you know, that's where the grid, that's where the grid cell kind of property comes from.

It comes from whatever that constraint is, that, you know, kind of, you know, Determines the possible states [00:28:00] that the population can take, you know, as a collection. So I don't understand any of that stuff. I mean, I hear it, but I don't have intuitions about what that tells us about how the brain represents.

I mean, that's going to be a part of the answer to the story of how the brain represents. So it goes one step beyond this notion of a distributed code. I mean, so, you know, to step back into that lecture, I mean, I went from talking about, you know, the retina. to talking about these top, the topographic maps that what finds in the visual cortex.

Again, it doesn't matter that, you know, the, the input to the, to V1 is arrayed topographically from a, from a representational perspective, from a cognitive representational perspective. Again, nobody's looking at it, right? The fact that it's done topographically has obvious, uh, computational advantages. I mean, it, you know, things that are, Near each other may be part of the same object.

For example, you know, [00:29:00] pixels, voxels in space. I mean, so to speak. I mean, there's, there's some real advantages to having a topographic code represent, especially the spatial aspect of things. You don't get this in, you know, in the auditory cortex. You only get this in the visual cortex. You get this in somatosensory cortex and so on.

You don't get it with olfaction. You don't get it with taste. You don't get it with audition because they are the, they, they're, it wouldn't serve the same purpose there. You're not talking about things that are nearby in space. 

Andrea Hiott: let's, let's define this a little bit because this is a really interesting part of the history of trying to understand cognitive neuroscience in the way we just brought up and getting to what you were just describing of this population coding now and thinking more in terms of.

Even maybe that embodied idea of something ongoing that we're representing. And so the brain's not necessarily representing, but before we get there, the topographic map, I think is a great place to kind of like sit in this for a minute, because so we [00:30:00] started with, we have this feeling of mental, physical, internal, out, out, turn on the external.

And I think you talk about Plato and Aristotle and this kind of debate. Is it internal? Is it external? and then we get to dualism and Descartes and, but really what we're trying to figure out is. where, what's happening here, is it was something was just all in our head from the beginning and in terms of the way you described the, the rats that are born, right?

is everything like that given to by God? 

Lynn Nadel: This is the, this is the argument that Busaki is basically has joined. I mean, this, the inside out versus outside in approach, I mean, is still either 

Andrea Hiott: or, which I'm against the either or, 

Lynn Nadel: but it's got, that is right. That's clearly right. So I think I may have already told you that I'm, that Mary Peterson and myself and Drew Maurer and Sarah Burke in University of Florida, they were former students of, of Bruce McLaughton and Carol Barnes, we've been working for several years now, just slowly working and working our [00:31:00] way into trying to, uh, spell out a hybrid, a hybrid between the inside out and outside in approach to thinking about how the brain represents meaning, you know, I mean, it's essentially that the question we're talking about today, uh, we have made very little progress so far.

Andrea Hiott: I actually don't think we've talked about that yet. And that's really interesting that that's going to have to I need to like read up on that because I, I really feel like holding the paradox. That's how I say it philosophically is like, I think the hippocampus is like trying to help us do that. Right.

Because you can't go in either direction all the way. You need both. So how do we do it? And it's, it's hard. 

Lynn Nadel: How to think about, you know, the fact it can't be one or the other, it can't be an either or. Somehow. It can't be. Or it's both. I 

Andrea Hiott: mean, yeah, it's, it's like it's, it's a new way to have to process this.

I think that's, it's that I think all this research that you're involved in, at least from my perspective, is showing us a way to do that. But it's very hard because you have everyone in their own camps trying to kind of prove, and that's part of the process [00:32:00] itself. But I don't wanna get too distracted away from.

Topographic maps yet, because this word map is really important. Yeah. And I think it can kind of like lead us because Yeah. Yeah. And there's this very cool thing in case people don't know the um, is it Penfield who came up with a sensory or the sensory ho homunculus? Was it Penfield? That kind of mapped it?

You've probably seen it like a picture of the brain and there's this weird creature. That's the somatic. Yeah, 

Lynn Nadel: that's the somatic. I'll show a 

Andrea Hiott: picture of it, but basically what that's showing is that in the brain, um, most people's brains, there are certain areas that are associated with certain parts of the body, right?

You can sort of, it's not, like map is a tricky word, we could get into that, but more or less within the brain as it's developed with the body, there's a certain part that's got a lot of attention towards, for example, the hands, Sure. Or the lips or, or so on? Well, it's 

Lynn Nadel: usually, it's, I mean, what we're, no, what we're finding out, and that was what the Coley Prize was about, was the face systems.

It's, it's usually more than one area. I mean, the sensory homunculus that [00:33:00] Penfield pointed out, you know, would make you think that, you know, there's this one place in the brain where the face is represented. Well, no, actually, there's about seven or eight face patches, it turns out, you know, of, of increasing degrees of complexity, you might say, and increasing degrees of invariance when you get to the, So the top of that hierarchy, you have a system that is representing a face, no matter which angle you're seeing it in and so on.

So, so, but basically, yes, the brain has these somatosensory and motor. I mean, the motor system is the same. 

Andrea Hiott: And that's so important what you just said, because I think even in a lot of ongoing neuroscientific study, it's still taught in the old way, not in the way you just said. Yeah. That there can be many different places where this is happening. But it doesn't change, that's the either or, too. It doesn't change that actually there is associated regularity. 

Lynn Nadel: Right. I mean, this is not a 

Andrea Hiott: map like in this way we thought. 

Lynn Nadel: That's the localization kind of argument, basically. You know, is the face [00:34:00] system localized to one part of the brain?

The answer is no. We now know it's distributed in, you know, into several. But within, but each of the patches, may have quite a very specific function. There may be specialization within each of the face patches. It's not as if all these patches are equivalent, you know, and they're all doing the same thing.

And it's 

Andrea Hiott: not, yeah, it's not like they're changing all the time. So I think to try to connect it to what we were talking about before, you know, we come into, we're trying to understand how the things that we are aware of our experience are related to life and how the brain is doing it. so for example, with this map, you can kind of understand that certain sensory input.

So for example, if you hurt that part of the brain, for example, in that individual, then it's going to affect that part of their bodily experience of the world and movement. Undoubtedly. 

Lynn Nadel: Exactly right. that's the connection, right? Yeah. That's the connection. But things like on are all, you know, relevant to this and Ramachandran has done some really lovely work along the, about this kind of stuff.

[00:35:00] Right. So what do we make of that though? I mean, again, that's a, you know, that, that's sensory homunculus that Penfield, and by the way, he's part of the history lecture that I'm putting together because Penfield Well, I mean, 

Andrea Hiott: it even goes back to McGill too, you know? 

Lynn Nadel: Exactly right. And he was, he was a critical link between, the neurosurgeon who did the surgery on H.

M. and Brenda Milner who ended up studying H. M. and Sue Corkin, Penfield was the critical link. Funny. He 

Andrea Hiott: brought in Milner, right? Or 

Lynn Nadel: he brought, well, he, he brought in heb, who brought in 

Andrea Hiott: heb. Who brought in Milner. Right. 

Lynn Nadel: Brought in Milner. Who brought in Cork. Who sent Cork in to work with Milner on. Amazing on, 

Yeah. Tangled and Penfield is part of the story, which is kind of cool. Yeah. Right. So that, I mean that, you know, that too is a little bit like the. You know, image on the retina. I mean, we don't, you know, yes, the brain is organized in that way that there are these topographic maps, so to speak, they are distorted visual system is even [00:36:00] distortion within the visual system is, you know, asymmetries and all kinds of eccentricities and so on.

It's not a kind of a Flat map, you know, that accurately represents the 3d structure of what we seem to perceive as a Euclidean world That's not the way that exactly but it's roughly topographical because that there's real Computational advantages to that and the same must be true in the somatosensory maps There must be there's got to be computational advantages to having you know If those things represented in neurons near each other I mean for start then you're then this becomes a wiring issue And I think I mentioned it, and I don't know that I mentioned it in lectures, but I probably, in the chapter that I could never, that I didn't manage to get, the 1980 chapter, you know, the, the, the computational advantages of, of, of having things close to each other involves this sort of minimum, minimum wiring constraint, you know, which evolution [00:37:00] presumably prefers.

you, you want to have things that need to talk to each other, As close to each other as possible. You also need to have long range communications because, you know, et cetera, to the extent to which you can. have nearby things, uh, that, you know, that are functionally near each other, that, you know, that's, that saves extra wires, which saves metabolism, which, 

Andrea Hiott: and by wire, you're talking kind of like Hebbian, 

Lynn Nadel: synaptic, what do you mean by wiring?

That's like a separate issue. No, this, this is just an issue of, of development. I mean, when you're, when the brain is developing, I mean, it, it takes, it takes, so they're 

Andrea Hiott: literally connected with by synopsis or how do you, it's a lot of 

Lynn Nadel: energy to, to, to make connections between neurons and the, and the, the greater the distance between two neurons that are meant to talk to each other, you know, because they have some similar, some similar function.

The more energy it takes to More 

Andrea Hiott: electricity. So you're literally talking about I'm really 

Lynn Nadel: talking about the connection, the 

Andrea Hiott: nearness in [00:38:00] space. Yeah. 

Lynn Nadel: The nearness in space, you know, is a, is a big advantage from, uh, you know, all of the things being equal. It's a big advantage to have things near each other if they're doing, if they're doing something similar.

That's why the absence of any topography in the hippocampus initially struck people as, this is so crazy. 

Andrea Hiott: Basic, 

Lynn Nadel: have the neurons that represent two places in the world that are really close to each other in the world. They may not be anywhere near each other in the hippocampus. They could be, you know, it's random.

You know, it seems like, you know, there's been some argument about that. But, so the hippocampus was this non topographical map. That's what made it so kind of cool, initially, in the context of what we knew about visual maps. It was something that, you know, it's not only visual, we, it was known early on that it was more than just visual.

But, you know, most of the experiments, you know, default to vision. Yeah, I mean, the rat's moving around the world, it sees what's out there, blah, blah, blah. [00:39:00] And yet, the way this, the way the brain mapped it, Wasn't topographical. So, and that, 

Andrea Hiott: I think that's part of that either or holding the paradox coolness of the hippocampus too that we, that everyone's having to deal with that, but this is very interesting because let's like, okay, so this, this idea of top topography is quite amazing, right?

Like this was an amazing thing to figure out that within this organ in our body, probably different for everyone, but as you develop, uh, So probably you come with certain regularities that everyone shares, but as you develop certain parts of your brain are going to correspond to certain parts of your movement and your sensation and the body parts, right?

And that's fascinating and so cool. And then we thought of that as a map, right? That you can map this on to the brain. And this is where the representation gets confusing because topography doesn't solve the problem of representation. It doesn't solve any of that stuff we were talking about, but it starts to seem like now we have a representation, but actually we've drawn a diagram, which is the representation of [00:40:00] kind of being able to create another third thing, which is a kind of map of like, okay, this part of the brain corresponds to this part of the body.

But then, like we were saying, people start thinking. There's a map in the brain, and this gets kind of confusing. That's exactly 

Lynn Nadel: right, exactly. I mean, it, it solves no problem at all. I mean, it solves the mechanistic computational problem clearly, 

Andrea Hiott: but not the meaning problem. That's how you put it in your But not, 

Lynn Nadel: but not the meaning and representational problem.

So, I mean, so a lot of the work that is being done is really focused on the mechanistic problem. I mean, how is the system doing, you know, creating these maps and how are these things being, and how are these things used and so on, but, and how do we 

Andrea Hiott: know it? Like how is this experience that, right? Like yes, we found that wonderful correspondence and that tells us something.

To then think, Oh, well, that's what's happening. That's how we have this little movie in our brain. No, it's too, it's too confusing, but we don't have this little, 

Lynn Nadel: we don't have that. [00:41:00] And I don't think quite honestly, I mean, I, I certainly don't have any. really clever ideas about it yet, and we're having, you know, I don't know, this week there's going to be a visitor here who's, uh, who is a, from Israel, a guy, Yoram Burak, who's, uh, collaborates with, uh, with Edvard Moser, and probably my Brit as well, and, and he's a former student of, uh, of, um, Sampolinsky, I can't remember Sampolinsky's first name.

He's really one of the grandfathers of computational neuroscience, 

Andrea Hiott: you know. I'm, a lot of papers are coming through my mind right now. 

Lynn Nadel: Trying to sort of figure out how a tracker networks and how all these things end up representing. I mean, that's really what they're trying to get at, but, but they're really working on the mechanistic issues.

I mean, how does it do the job that it does? And they don't really, unless until maybe until you liquor them up a bit, they don't, they don't want to, they don't necessarily want to talk about. The meaning question. I mean, how does this [00:42:00] set of activities come to represent something in the way of meaning that thing, you know, now, or how does 

Andrea Hiott: it result in kind of experience?

And I mean, we don't even have to like, get into that. But it's interesting that you bring that up, because right, I think, you know, You know, we're kind of jumping around, but we, we got to this idea of it not being a map in the brain, but for a while we sort of thought, okay, there's like a little picture in the brain and there's a topographic map and there's an image and so on and through the, now we still confuse all of these words.

Even thinking about computational representation in the brain is a similar, I think a similar mistake to thinking of maps in the brain, but it doesn't mean the word map or the word. Computation is like wrong. It's just that we get like, very confused, you know, 

Lynn Nadel: about I don't think it touches the problem at all.

So, so you get, so you get somebody like Tim Behrens, you know, who's arguing that some kind of a geometric six fold representation is the common code for the way the brain represents information. [00:43:00] It's going beyond the, you know, building off the grid cell. Notion, you know, and how well the grid cell population tiles, the whole environment, 

Andrea Hiott: you know, 

Lynn Nadel: he's jumped, he's taken that idea and sort of said, well, you can find this kind of six fold representational structure to the to the population code again, all over the brain, he's arguing, and I think I and I talked to john about this as well.

And john, we also think that he's probably gone too far here. But even if that were the case, Even, and you think about the grid cells, I mean, what is it about the, that particular computational structure that causes it to mean what it means? 

Andrea Hiott: Mm-Hmm. , 

Lynn Nadel: you know, or that we think it means, so to speak, that it, that it, what it means is something about the structure of the space that the, that the or animal is moving around in.

Andrea Hiott: This is great because I think too that he's gone too far so to [00:44:00] speak and trying to be so specific about the sixfold so on and so forth. Um, but what I like about his work in that Tolman Eichenbaum machine is exactly that he puts Tolman and Eichenbaum together because I mean, we kind of skipped over, like, so thinking about maps, and then I think in your lecture you go into sort of feature detection and, um, contrasts and Hubert and Wiesel and all this, and it's kind of moving more towards where we are now, population coding, right?

Where you're, you're looking at regularities and so on and so forth. And I bring that up. But then also the Tolman iken bomb. Like I, I would like to do, to hear your perspective about, like, I hear, do those not fit together? You know, Iken bomb's idea and, 

Lynn Nadel: well, what's the idea, what do you see as the core idea in the, in the, in the Toman iken bomb machine?

What, what is it doing? 

Andrea Hiott: Well, I mean, I, I think I would need to think about that a little bit more, but I'll tell you what I'm trying to get at here in terms of this conversation. So Tolman is associated with the cognitive map, for example, right? Or the idea that. when a rat is [00:45:00] moving through its spatial location, that's also a kind of knowledge, so to speak, and that we could map it.

I'm now giving him words he doesn't necessarily use, but in the same way we draw these little homunculi kind of things, we could probably do that with certain individuals or certain rats in terms of how they're moving through. space and how certain parts of whatever is happening in the hippocampus, um, is happening, right?

And it gets way too confusing. I'm not saying it's a six fold this and that and that. But Sure, 

Lynn Nadel: sure. Tolman didn't care about that. I mean, he wasn't That, I 

Andrea Hiott: No, he doesn't care. Tolman was not 

Lynn Nadel: into the brain. Tolman Right. Tolman was just talking about the cognitive structure. 

Andrea Hiott: But, but that moving through a space is a kind of knowledge, right?

I just think that's an obvious kind of thing that we can say 

Lynn Nadel: The knowledge that Tolman claimed was the knowledge, the kind of Uh, what leads to what knowledge? I mean, what Tolman claimed was that the animals form a, a kind of a mental map, a map of the world, something like a map of the world in their, in their head.[00:46:00] 

Andrea Hiott: Something like parts of the brain being associated with regularities in the way we described with the topographic map, but not so hard and fixed as that, but something like that going on. If 

Lynn Nadel: you pushed him, he might have said that, but he really didn't ever talk about 

Andrea Hiott: that. Yeah. But that same kind of idea, right?

That Yeah. Yeah. As you develop, of course, you kind of associate per certain regularities with certain 

Lynn Nadel: Sure. Whatever 

Andrea Hiott: functions. Yeah. 

Lynn Nadel: That would be the modern way of talking about it. So that's the toman part of it. Yeah. Tolman talked about rep, about the representations that our brains must be forming, and the fact that they can be used as predict in predictive mode that, you know Mm-Hmm.

Andrea Hiott: Good way to say it, yeah. 

Lynn Nadel: And that basically they tell the animal, if I do this, then the following is going to happen. You know, he, you know, he, he connected all of those dots cognitively. Right, which is, 

Andrea Hiott: which is great because that's kind of like a map, right? Because you use it in order to sort of infer where you're going to go.

Totally, that's the 

Lynn Nadel: whole idea. That's why O. P. and I built on that. Exactly. 

Andrea Hiott: And that goes into the beautiful book, which we've discussed, Hippocampus as took that as a starting. 

Lynn Nadel: But so what, [00:47:00] what, but so now tell me about the Iconbound. Iconbound part of it. 

Andrea Hiott: Okay, well this is what I don't think, I think I'm missing something because I feel like there's a lot of controversy or fighting about something, I don't know that I really understand Eichenbaum totally with this idea of association, I guess what I, what I think is kind of clear and what I like about the Tolman Eichenbaum is that, We can understand, we could probably find some way, I don't think anyone's found it, but to understand that the same way that we study how, for example, we move through physical spaces, and that all of this that we've been talking about, there are regularities, and we could probably find maps, And I mean that external maps that we draw or computational models that we make is what I mean by representation.

That we could also do that with other spaces, because we're setting what a space is. You set the little room for the rat, but you could also set a little knowledge space, so to speak. And for me, it's still all regularities that we've learned, and you're still moving through a space in a similar way.

I don't mean that, [00:48:00] like, the way we move through a room and the way we move through a book are gonna look the same, but there's probably some kind of pattern or regularity. towards how we could understand those processes that is the same. That's how I see that connection made in a nice way. But I could be wrong.

I mean, I don't understand what Ikenbom is so controversial about. 

Lynn Nadel: Well, I think the controversy comes from the fact that, you know, th thi this idea is built on the kind of, uh, I can bow me in, uh, co I can bow in Cohen really notion of, of relational memory, you know, and the, and, and the, the brain is coding these relations.

You know, and the hippocampus in particular is a relational memory device. So 

Andrea Hiott: that would be this either or thing, right? So that then precludes all the other stuff we're talking about. Is that kind of Well, not really, 

Lynn Nadel: because it, because since the, I mean, they may think it does that. I 

Andrea Hiott: don't think it does, but it seems like people take it that way.

And then, and then I can understand the controversy, I guess. 

Lynn Nadel: it's the, it's, I don't think the idea is so much as, is so much [00:49:00] controversial as vacuous. 

Andrea Hiott: Okay, well what, what is the idea that you, that, because I think I'm missing what that is. 

Lynn Nadel: The vacuous part is that. Is that Eichenbaum talked about this as a, as, as one of, as one piece of the kind of brain's function, this relational device, right?

You know, the hippocampus is specialized to kind of create these relations, you know, and it does it for space and for all these other things as well. Right? That's the point you're making. The problem is everything the brain does, not just the hippocampus, everything the brain does is relational. There is no non relational part of the brain.

It does not exist. It's a nonsense idea. Every neuron gets inputs and is relating inputs from multiple sources. There is nothing that is non relational. It simply is not a, it's not a useful explanatory idea. So to the, in my view, [00:50:00] and also John and I are very strongly in agreement on this. There's, there's just no, it doesn't help you.

everything is related. 

Andrea Hiott: So that he's saying that, 

Lynn Nadel: so 

Andrea Hiott: is he saying the hippocampus main purpose is to relate? 

Lynn Nadel: Yeah, his, yes, uniquely so. Okay. And there are other, other parts of the brain don't have this kind of special, you know, ability to relate things to each other. Is the, is the, is the core of the Eichenbaum Kohn relational idea, and that is built into this Tolman Eichenbaum approach, you know, that, that you have this unique relational device, but that's crazy.

The whole brain is a relational device. Everything the brain does is relational. There's no Okay, 

Andrea Hiott: see, that I didn't get at all, that it had to be a device that's relational. To me, it was much more of a theoretical, um, very much grounded in Kind of things you start with in your book with space and how we, how we understand space and as 

Lynn Nadel: you sell, as you [00:51:00] said yourself, they're talking about it as an association machine.

The Toman I and bound machine is a machine that makes associations. But ev but that's an association is just another word for a relation. It's, and the brain is in the business of, of everything is associative. There used to be in psychology, this kind of big distinction between associative and non associative learning.

As if there could be such a thing as non associative learning, right? Non associative I 

Andrea Hiott: think it's still talked about as if, as if associative I mean, people don't talk the way I, I agree with what you're saying, but This is confusing because when, in all brain research, we don't talk about the brain as being like that.

Lynn Nadel: Yeah, no, that's the reason why there's this controversy that some people are kind of taken up by this idea. Oh, that's a really cool idea. You know, you've got this special relational associative device that told when I can bow machine blah blah blah Without actually kind of digging deeper and you know trying to say well, okay.

What's the rest of the brain doing? Is it doing non [00:52:00] associative things? What does that mean? Every part of the brain is doing associative things. There's no there is no distinction Otherwise, you know, otherwise the brain would just be a bunch of isolated wires, you know, going from input to output. There'd be nothing else going on.

I 

Andrea Hiott: agree, but we don't, we talk about associative memory as if it's one kind of memory. We don't talk about all memory as associative. 

Lynn Nadel: What I'm trying to tell you is that so called non associative memory, which were things like habituation, sensitization, they're not non associative. 

Andrea Hiott: I agree 100%, but it's not the way you're taught that, you know.

So I can just imagine a lot of people aren't even understanding that 

Lynn Nadel: that's 

Andrea Hiott: what he's saying, you know. You're 

Lynn Nadel: absolutely right. The objection I'm making is not one that is widely accepted. Kind of mooted in the, you know, in the, in the literature at this point, but sooner or later, people are going to realize that.

It's a vacuous, that this idea, I think, they're going to realize that this is a vacuous idea, it doesn't get you anywhere, 

Andrea Hiott: basically. I [00:53:00] don't think it's vacuous, but I think it's not, um, like an answer. It's a, for me, it's like a tool to rethink some of these things. even, you know, Tolving, I love Tolving and these different kinds of memories, but Right.

We do need to do some rethinking about how we, you know, Categorize all these memories and things and I guess like being a little bit kind of, you know, not really under I haven't studied I have studied I can bomb and all this from an angle that I from which I want to see things, right? Not and everyone's doing that so I can see how this gets incredibly confusing But to just not try to stick it to all to to to like a theory I think what's interesting is like for me and you might really disagree with this is like You That doesn't seem so far from a cognitive map in the Tolman sense of like, I wouldn't say, for example, that, okay, we're just, just because we can understand that, uh, cognition is, um, that when we were moving through a space that is also a kind of knowledge, then we just say, oh, okay, everything [00:54:00] is movement and everything is knowledge.

I mean, we could also kind of do that too, right? And that would be vacuous. Um, but instead, if you really look at. at what's being said there, and you start to understand, um, there's actually very big, huge differences in terms of these parts of the brain, or even if not, right? Even if some other part of the brain could become something like the hippocampus, it would still be interesting that the brain itself, some, in some way, is developing some kind of regularity, That can then be used in many different situations to 

Lynn Nadel: yeah, I believe, however, that every part of the brain is doing what you're just saying that that is not unique to any particular system.

That's just the way the brain works in. Every part of the brain is extracting is engaged in extracting the regularities from the input patterns that it receives. Basically, and, and those input patterns necessarily include relational [00:55:00] information. They have to, they always do. They're not about, like, one point in space.

They're always about things that, that involve relations. So my problem with that approach is that it doesn't seem to me to add any useful explanatory power to the, uh, To any other story that one, you know, that one, it's, you know, it's basically gets back to everything is associated, you know, everything is associative.

And you know that again, the philosophers were okay with that idea, you know, that the brain works on the basis of associations. That's, that's what it does. And it's not this part of the brain that works on the basis of associations and extraction of statistical regularities and so on. It's every part of the brain.

Okay. is doing exactly that. 

Andrea Hiott: That's kind of incredible. I mean, I think if you take, we don't have time to go into all of your work, but the things we've talked about in other discussions together, and the reason that I believe this whole kind of toll on [00:56:00] through you, through the Mosers, all the stuff that you're now celebrating there, I think at the, in Tron time, I think this is incredibly important because It does show us something that does tell us something about what we were trying to talk about, about, how we can be in the world and experiencing the world, and that's like a continuous thing.

Lynn Nadel: It does, absolutely it does, but we're back to the kind of inside out versus outside in. But why does it 

Andrea Hiott: have to be either or? I mean, this is the No, 

Lynn Nadel: it is. You're right. And what is the, what is the magic sauce that is going to help us understand, you know, how both of them, both the internal structure, like that shows up at day 10, you know, independent of experience, and the actual experience that the organism has.

Which actually then refines the shape of the torus and refines, and then the grid cells emerge after the torus. 

Andrea Hiott: Maybe it is something like the association though, and I don't [00:57:00] mean that in a vacuous way, but I mean it connected to all the research you guys are doing. It is. You start to think of the brain in that way.

It is. And you think of it in that immediate sense you brought up at the beginning. Actually, we get somewhere really new and beautiful. 

Lynn Nadel: I hope you're right, but I'm, 

Andrea Hiott: but the problem is to go back to representations is we can't get rid of that trying to find it in the brain or find it in the world, right?

Instead of understanding the association as a process that can't be isn't represented in the brain or the world, but we can represent. With the books we write and the computational models we make and the images we draw, 

Lynn Nadel: I mean, the notion of a representation in the brain may just be a slice through, through a moment in time, and that the representation is really some combination of the structure of the brain and the structure of the, of the world and the inputs from the world to the brain and the, and the tight coupling between those two.

and the kind of compromise between those either or positions is figuring out how that coupling works. [00:58:00] Basically. And when you say, you know, this activity in the brain represents X, X about the world, then something about the world is, you know, part of that story. It has helped create that, you know, that's that set of brain activities, either phylogenetically or ontogenetically.

And, you know, the answer is going to be found somehow in the interactive kind of reentrant, you know, recursive, you know, sort of language that the brain uses, you know, to sort of interact with the world. And that's kind of what we're working on and trying to figure this out, is the, the, the middle, the middle ground has to be, you know, somewhere between those two.

And, and how does it, and how does a, how does a particular network come to, you know, Have the meaning that it has. We're no longer talking about patches or maps, but you know, an entire network or population of, of cells, how did they come to mean what they mean? And how, and how did they come to have the power they have to, to [00:59:00] generate behavior, so to speak.

And it's gotta be some interaction between what's out there in the world and the experience the organism has and the, and the kind of pre wired structure of the system, which was pre wired because of millions of years of, uh, of evolution, you know, that built it that way because it actually worked in the world.

And so it's got to be connected to the world in that way. Not a free device, basically. The point I was trying to make about Tolman Eichmann was that no matter how you think about this, it's going to be an associative device of some kind. And so yeah, so yeah, 

Andrea Hiott: that's, that might be the contribution that I'm thinking he's bringing because, uh, I don't think we talk about it like that, and I don't think it's actually vacuous to talk about it like that.

If you, if you bracket it in the way we're talking about, not if you just say, okay, the hippocampus is this little device in the brain that does this, okay, that's, and it does it through this and this and this, okay, then we're getting, like, that's not [01:00:00] going to help us. 

Lynn Nadel: I'm open to that possibility. Yeah. 

Andrea Hiott: But I see, I do see a way that those things aren't, There could be help helping each other this tradition that is, you know, so important to me that you guys are all there are doing and what he was trying to say, sometimes in probably almost a cartoonish sense about about there being a way in which, um, this is happening in all these different contexts, you know.

Lynn Nadel: That's the question, and how does that, and how does that work? But you know what? What believe it or not, we've, we've run out of time. 

Andrea Hiott: I know, I know. Well, you have to go. At least for me, 

Lynn Nadel: I have to, I have to quit now. Yeah, me too. So, we can, yeah, so we can pick this up again, you know, next month, you know, we can set up another talk back in Tucson.

Andrea Hiott: Yeah, will you, um, can I read your, your talk that you're going to give there? Maybe, uh, 

Lynn Nadel: I will, or some part of it, this history thing, 

Andrea Hiott: yeah, or, or, or send me some of the stuff you were just talking about, the hybrid stuff too. 

Lynn Nadel: Uh, that, that's [01:01:00] not ready. That's not ready. 

Andrea Hiott: Well, then maybe your talk that you, or something, which is 

Lynn Nadel: really a different thing.

It's just interesting history. Uh, I can send you the, once I have the PowerPoint finished, then I can send you this, then I can, you know, and I think a lot of it on the slides. 

Andrea Hiott: I mean, 

Lynn Nadel: some of it, some of it won't be, but most of the, most of the story will be on the slides. 

Andrea Hiott: Okay. That would be be great. I can 

Lynn Nadel: that, yeah.

Okay. Let's 

Andrea Hiott: do that. 

Lynn Nadel: I'm done with it. I won't be done with it for another week or so, but I'll, when I'm done with it, I can send it to you and we can Okay. Well, 

Andrea Hiott: I'm in, I'm in research mode, so I'm gonna be, I'm finally staying still, so when you get back and settled, just let me know. We can, I'm back 

Lynn Nadel: the 2nd of October, so we can set something up for the middle of October.

Yeah, I'm around 

Andrea Hiott: in October or so months from 

Lynn Nadel: now. 

Andrea Hiott: Okay. That would be perfect. Yep. Sounds good. 

Lynn Nadel: It was fun. Have fun there. 

Andrea Hiott: Cool. Yeah. Always fun. 

Lynn Nadel: Oh, send me the paper.