A (25:25)
So now I want to talk about auditory learning and actually how you can get better at learning information that you hear, not just information that you see on a page or motor skill learning. So there's a phenomenon called the cocktail party effect. Now, even if you've never been to a cocktail party, you've experienced and participated in what's called the cocktail party effect. The cocktail party effect is where you are in an environment that's Rich with sound, many sound waves coming from many different sources, many different things. So in a city, in a classroom, in a car that contains people having various conversations, you somehow need to be able to attend to specific components of those sound waves, meaning you need to hear certain people and not others. You and your brain are exquisitely good at creating a cone of auditory attention, a narrow band of attention with which you can extract the information you care about and wipe away or erase all the rest. Now, this takes work. It takes attention. One of the reasons why you might come home from a loud gathering, maybe a stadium, a sports event, or a cocktail party for that matter, and feel just exhausted, is because if you were listening to conversations there, or trying to listen to those conversations while watching the game, it takes attentional effort, and the brain uses up a lot of energy just at rest. But it uses up even more energy when you are paying strong attention to something, literally caloric energy burning up, things like glucose, et cetera. Even if you're ketogenic, it's burning up energy. So the cocktail party effect has been studied extensively in the field of neuroscience, and we now know at a mechanistic level how one accomplishes this feat of attending to certain sounds, despite the fact that we are being bombarded with all sorts of other sounds. So there are a couple ways that we do this. First of all, much as with our visual system, we can expand or contract our visual field of view. Okay, we can do that. We can expand and contract our visual field of view. Well, we can expand and contract our auditory field of view, so to speak, or our auditory window. We can really hear one person or a small number of people amidst a huge background of chatter, because we pay attention to the onset of words, but also to the offset of words. So one of the more common phenomena that I think we all experience is you go to a party and. Or you meet somebody new and you say, hi. I would say, hi, I'm Andrew, and they'd say, hi, I'm Jeff, for instance. Great, great to meet you. And then a minute later, I can't remember the guy's name. Now, is it because I don't care what his name is. No. Somehow the presence of other auditory information interfered. It's not that my mind was necessarily someplace else. It's that the signal to noise, as we say, wasn't high enough. Somehow the way he said it or the way it landed on my ears, which is really all that matters, right? When it comes down to learning, is such that it just didn't achieve high enough Signal to noise. So the next time you ask somebody's name, remember, listen to the onset of what they say and the offset. So it would be paying attention to the J in Jeff, and it would be paying attention to that in F in Jeff. Excuse me. All right. And chances are you'll be able to remember that name. Now, I do acknowledge that trying to learn every word in a sentence by paying attention to its onset and offset could actually be kind of disruptive to the learning process. So this would be more for specific attention. Using the attentional system, we can actually learn much faster and we can actually activate neuroplasticity in the adult brain, Something that's very challenging to do. And that the auditory system is one of the main ways in which we can access neuroplasticity more broadly. I'd like to now talk about balance and our sense of balance, which is controlled by, believe it or not, our ears and things in our ears as well as by our brain and elements of our spinal cord. The reason why we're talking about balance and how to get better at balancing in the episode about hearing is that all the goodies that are going to allow you to do that are in your ears. They're also in your brain, but they're mostly in your ears. So as you recall from the beginning of this episode, you have two cochlea. Cochleas that are one on each side of your head. And that's a little spiral snail shaped thing that converts sound waves into electrical signals that the rest of your brain can understand. Right next to those, you have what are called semicircular canals. The semicircular canals can be best visualized as thinking about three hula hoops with marbles in them. So imagine that you have a hula hoop and it's not filled with marbles all the way around. It's just got some marbles down there at the base. Okay. So if you were to move that hula hoop around, one of those hula hoops is positioned vertically with respect to gravity, but basically it's upright. Another one of those hula hoops is basically at a 90 degree angle, basically parallel to the floor. If you're standing up right now, if you're seated. Okay. And the other one is kind of tilted about 45 degrees in between those. Now, why is the system there? Well, those marbles within each one of those hula hoops can move around, but they'll only move around if your head moves in a particular way. And there are three planes or three ways that Your head can move. Your head can move up and down like I'm nodding right now. So that's called pitch. Or I can shake my head. No, side to side. That's called yaw. And then there's roll, tilting the head from side to side, the way that a cute puppy might look at you from side to side. Pitch, yawn, roll, are the movements of the head in each of the three major planes of motion, as we say. And each one of those causes those marbles to move in one or two of the various hula hoops. Okay, they aren't actually marbles, by the way. These are little, little, kind of like little stones, basically, little calcium like deposits. And when they roll back and forth, they deflect little hairs, little hair cells that aren't like the hair cells that we use for measuring sound waves, but they're basically rolling past these little hair cells and causing them to deflect. And when they deflect downward, the neurons, because hair cells are neurons sending information up to the brain. So if I move my head like this, there's a physical movement of these little stones in this hula hoop, as I'm referring to it, but they deflect. These hairs, send those hairs, which are neurons, those hair cells send information off to the brain. Any animal that has a jaw has this so called balance system, which we call the vestibular system. One of the more important things to know about the vestibular, the balance system is that it works together with the visual system. Let's say I hear something off to my left and I swing my head over to the left to see what it is. There are two sources of information about where my head is relative to my body, and I need to know that. First of all, when I quickly move my head to the side, those little stones as I'm referring to them, they quickly activate those hair cells in that one semicircular canal and send a signal off to my brain that my head just moved to the side. But also visual information slid past me, my, my field of view. I didn't have to think about it, but just slid past my field of view. And when those two signals combine, my eyes then lock to a particular location. Now, if this is at all complicated, you can actually uncouple these things. It's very easy to do. If you get the opportunity, you can do this safely. Wherever you are, you're going to stand up and you're going to look forward about 10, 12ft, you can pick a point on a wall, stand on one leg and lift up the other leg. You can bend your knee if you like, and just look off into the distance, about 1012ft. If you can do that, if you can stand on one leg now close your eyes, Chances are you're going to suddenly feel what scientists call postural sway. It is very hard to balance with your eyes closed. You might think, well, and if you think about that, it's like, why is that? That's crazy. Why would it be that it's hard to balance with your eyes closed? Well, information about the visual world also feeds back onto this vestibular system. So the vestibular system informs your vision and tells you where to move your eyes. And your eyes in their positioning tell your balance system, your vestibular system, how it should function. So up until now, I've been talking about balance only in the static sense, like standing on one leg, for instance. But that's a very artificial situation. Even though you can train balance that way. Most people who want to enhance their sense of balance for sport or dance or some other endeavor want to engage balance in a dynamic way, meaning moving through lots of different planes of movement. For that, we need to consider that the vestibular system also cares about acceleration. So it cares about head position, it cares about eye position and where the eyes are and where you're looking. But it also cares about what direction you're moving and how fast. And one of the best things that you can do to enhance your sense of balance is to start to bring together your visual system, the semicircular canals of the inner ear, and what we call linear acceleration. So if I move forward in space rigidly upright, it's a vastly different situation than if I'm leaning to the, to the side. One of the best ways to cultivate a better sense of balance, literally within the sense organs and the neurons and the biology of the brain, is to get into modes where we are accelerating forward. Typically, it's forward while also tilted with respect to gravity. Now, this would be the carve on a skateboard or on a surfboard or a snowboard. This would be the taking a corner on a bike while being able to lean safely, of course, lean into the turn so that your head is actually tilted with respect to the earth. The head being tilted and the body being tilted while in acceleration, typically forward acceleration, but sometimes side to side, has a profound and positive effect on our sense of mood and well being. And as I talked about in a previous episode, it can also enhance our ability to learn information in the period after generating those tilts. And that acceleration. And that's because the cerebellum has these outputs to these areas of the brain that release these neuromodulators like serotonin and dopamine. And they make us feel really good. Those modes of exercise seem to have an outsized effect both on our well being and our ability to translate the vestibular balance that we achieve in those endeavors to our ability to balance while doing other things. So I encourage people to get into modes of acceleration while tilted every once in a while, provided you can do it safely. It's an immensely powerful way to build up your skills in the realm of balance. And it's also, for most people, very, very pleasing. It feels really good because of the chemical relationship between forward acceleration and head tilt and body tilt. Once again, we've covered a tremendous amount of information. Now you know how you hear, how you make sense of the sounds in your environment, how those come into your ears, and how your brain processes them. In addition, we talked about things like low level white noise and even binaural beats, which can be used to enhance certain brain states, certain rhythms within the brain, and even dopamine release in ways that allow you to learn better. And we talked about the balance system and this incredible relationship between your vestibular apparatus, meaning the portions of your inner ear that are responsible for balance, and your visual system and gravity. And you can use those to enhance your learning as well, as well as just to enhance your sense of balance. Last but not least, I'd like to thank you for your time and attention and desire and willingness to learn about vision and balance. And of course, thank you for your interest in science.