That Neuroscience Guy - The Neuroscience of the Spins with Dr. Gordon Binstead

Episode Date: April 17, 2022

After a night out, we can experience strange dizziness that tricks us into thinking we're spinning when we're not. But why do we get these bed spins, and is it similar to how we get seasickness and other forms of dizziness?  In today's episode of That Neuroscience Guy, we discuss the neuroscience of Bed Spins and dizziness with the special help of neuroscientist Dr Gordon Binsted. 

Hi, my name is Olof Kregolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. Have you ever wondered about why you sometimes get the bedspins? Or why you might get sick if you're reading a book sitting in the back of a car? Well, today we're going to tell you all about that. And I have a guest to tell us. I'm going to introduce right now Dr. Gordon Binstead,

a neuroscientist at York University and a professor and a good friend of mine. Welcome to the podcast, Gordon. Well, thank you for having me. Great. Well, let's dive right into it. The neuroscience of bedspins. What's going on in the brain when people get bedspins? Well, the first thing you have to remember is that the brain, our human brains are very very dominated by vision. We really love vision. And so vision dominates everything we do in our day-to-day lives.

Now, when you choose to go out and have some libations with some friends, it mucks up what's going on in your ears. So all of a sudden, the fluids in your ears start spinning round and round and round. But when your eyes are open, your eyes tell the rest of your body, don't worry, we're not spinning over and over ourselves. And it cancels out what's going on in the ears. Now, when you go to bed and you close your eyes, then there's no vision anymore to keep things upright and you get the spins. That's fascinating. That leads me to an idea. I've heard that when you're out like on a boat, and I've tried this myself, you know, one of the ways you can avoid seasickness is to stare at the horizon. Is that sort of related to this?

It's the exactly same idea. Exactly the same idea. So you get sick when you're below deck because you have very little vision to be able to see around. But if you go outside, one, you get the fresh air, but two, you can stare at the horizon and your vision stabilizes

what your ears are doing. Going back to the bedspins, for one second though, there's another trick that people do for bedspins because of course you want to go to sleep. So you can introduce another sense that'll help stabilize what your ears are doing. And this is when people are sleeping with the bed spins and they put a foot on the floor. You put a foot on the floor to convince your ears that no, you aren't in fact spinning upside down.

That's a really cool idea. So, you're lying in bed, you think you're spinning, but when you put your foot down, that's sending a message to the brain saying, hey, we're actually not spinning. Everything's okay? That's exactly right, yeah. That's really fascinating. Let's dive into this a little bit more just in terms of the mechanisms in the ear. So what does it look like in there? You know, I've seen pictures of these weird loopy things. Tell us a bit more about that. I've seen pictures of these weird loopy things. Tell us a bit more about that. Well, yeah, so those weird little loopy things, as you say, are filled with fluid. And there are also little hair-type things in there as well.

And the combination of the little hairs and the fluid let your brain know what the orientation of the head is. Now, what happens when you've had a few libations, as we were talking about before, or actually in some cases if you have an ear infection, it can cause a similar problem, is that you get sort of inappropriate stimulation of those little hairs and they start firing as if the fluid was spinning around, which leaves your body to think that you're spinning around. Gotcha. So it's kind of like a gyroscope in our ear effectively. Yeah. And sort of orients you right side up. Okay.

So then we also, you're also telling me before we started recording that this is similar to like when you get sick reading a book in the back of the car. You know, I know this one personally because we used to go for long drives where I grew up in British Columbia and I love to read. And inadvertently, I pretty much always felt nauseous. Absolutely. So whether it's reading a book in the car, or as many people also find, you get sick, car sick, when you sit in the back seat of a car. Same basic idea. And the idea here is, again, the confusion between what your ears are telling you and what your eyes are telling you. So in this case, your ears are feeling the motion of the car

and are telling you we're moving. But when you stare at the book or at the back seat of the car, your eyes are saying, no, we're not, we're still. And you get that, once again, you get that confusion between are we moving or are we still? And in this case, that makes your tummy a bit upset because you're really confused as to what's actually happening. Gotcha. And this is, I think, would be different then. This wouldn't be the same as when you get airsick, would it? In principle, in principle. I mean, the motion on a plane is less obvious. So it's similar, like the motion on a train is less obvious, right? Generally, people can read on trains. The difference between planes, trains, and automobiles in this context, though, is that in a plane and on a train, there's a lot of other things, right?

You've got the entire cabin of the plane or the entire car of the rail, and those help stabilize things and make it less likely you'll get airsick or less likely you'll get trainsick. In a car, it's a really confined environment and you're staring at a screen. If you're in the front seat of a car, it's less bad because there's more visual stimulation. Yeah, you've got the whole panorama out in front of you as you drive. Yeah, I find that interesting because I know sometimes when I'm on a plane, you know, you almost don't know you're moving, right? Like, you know, if you get a modern plane like a Dreamliner and you're up at 41,000 feet, it's almost hard to tell you're in the air. Exactly. Exactly. Now, I mean, on trains, you do also get the strange phenomena when you walk in a train, right? And now all of a sudden, you know you're walking and you know how fast you walk.

Yet in one context, if you're walking with the train, your eyes are now telling you, or part of your eye is telling you you're walking at a normal speed, and another part of your eye is telling you you're walking at 40 kilometers an hour, or 50, or 60, or however fast the train is going. And when you turn around and walk the other way, your brain is telling you you're walking at 4 kilometers an hour, and the corners of your eyes are telling you you're actually traveling backwards at 40 kilometers an hour. Yeah, I found that interesting. You know, especially in Europe, I noticed some of the seats are backwards sometimes on the trains. And that can really mess with you. Yeah.

You know, at least when you're sitting facing forward, you get the sensation that you're at least moving in the direction that things are flowing. But I find that when you face backwards, that sort of turns you around a little bit. Exactly. Again, it's any of these situations where you have a mismatch between what your brain thinks you're doing and then what this visual feedback coming in. And actually, in neuroscience, as you know, we have a term for this. When someone says feedback, information coming in, we call it afference. And when it's feedback as a result of something you are doing yourself, we call it reafference. And it's when that reafference, when the reafference doesn't match what you expect, that you get sick and disoriented and these kinds of things.

That makes a lot of sense. So your brain's got multiple systems sending you information and the principle they should be redundant in some sense. But when you get mismatches, this literally confuses you. Exactly. Now, you mentioned this at the start. And we talked a bit about this in season one because we talked about the dorsal stream and the ventral stream and did a bit on vision. But why does vision dominate the brain so much? Well, I mean, vision is a very, very fast and very, very rich system.

And so it allows you to gather large amounts of information at once and in particular our vision system as you mentioned is actually split and it's split because the visual system generates so much information today would actually overwhelm us if we had to process it all at once and so in our case the visual system is split into one system that fudges out all of the details, gives you all the nice things like color and texture and all that fun information that attaches to memory. We call that the ventral stream. And then you have the other system that actually you have basically no conscious awareness of that sees in black and white, is very sensitive to movement and is very very sensitive to super super fine details but you only engage that system when you're about to move

right the dorsal stream yeah we talked a bit about that in in season one now um tell us a bit more about yourself though you're a neuroscientist like me um what did you do your studies in like when you were doing your PhD, what was the fascinating thing that got you into this field? So I was an athlete like yourself growing up. And so I was always really interested in movement and performance. And so that led me into kinesiology originally. And then I got a fascination for the brain. And so I started studying how the brain works and so throughout my graduate studies I was really looking at the interactions between the brain and

movement and vision and senses that's what I've spent my time doing and for my PhD we actually used some of the modern techniques of machine learning something called a dynamic Bayesian network to actually model how the brain controls movement using a relatively simple machine learning algorithm. Gotcha. That's really cool. This is an area we talked a little bit about before, which is this idea of using math to explain the brain. How well do you think it works? Like how close are these models to what's actually happening in the brain? They're not at all. Okay, interesting. So it's interesting. People use the term artificial intelligence,

not really realizing that artificial intelligence really is just very similar to the way that this recording is going to be captured on your phone. Data compression. Really, artificial intelligence, machine learning, are really just ways of compressing and summarizing data in a really, really concise way. and so even though we use those terms and we're using it to to model the brain if you will really we're just capturing and compressing and simplifying data in ways amazing makes ways that make it easier for us to understand but in no way is it actually an

encapsulation of what the brain is doing. It's a rubric, a summary, but it's not actually what the brain is doing. Yeah, it's a way to approximate that. I know that here in, I forget which university it is here in Ontario, but there is one person that's trying to build a brain, like a neural network where there's the same number of artificial neurons as there would be real neurons in the brain. But I know that that project is, you know, it's ambitious and it's going to take them quite a long time to get there. And of course, the challenge is that, especially with multi-node neural networks, as you know, is they capture lots of things, but it's actually very difficult to probe them afterwards to figure out what they've actually done. You know, there are some famous studies of machine learning where they were

trying to get, you know, machine learning algorithm to recognize a certain type of picture. And they thought they'd done the most amazing job until they realized that the two different pictures they had, one had a single black pixel while the other one didn't. And so even though they thought the machine learning algorithm had learned this amazing thing of how to recognize a face, it had actually just learned there was a black dot on one image. And that was enough for it to separate the two things out. Well, Gord, thank you so much for being on the podcast.

That was fascinating. A bit on the neuroscience of bedspins and other sort of illness-type phenomena that we might experience. Absolutely. Well, thank you for having us. And everyone, we're going to do this a couple of times in Season 3. We've got three guests planned across the 21 episodes. Remember, the website's up, thatneuroscienceguy.com.

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