That Neuroscience Guy - The Neuroscience of Driving

Episode Date: October 30, 2022

For a lot of us, driving a vehicle is a part of everyday life. It is an incredibly complex skill that requires rapid reaction time, decision-making, and action. In today's episode of That Neuroscience Guy, we discuss the neuroscience of driving. 

Hi, my name is Olof Kergolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. And we are back. Sorry for missing a week there, everybody. We had a short mid-season or mid-semester break, but now we're back on schedule. And my apologies, like I said, but sometimes my day job as a professor gets in the way of the podcast. Now, a fair number of you

listening have driven a car. The rest of you most likely have been in a car. But what's going on in your brain when you're driving? On today's podcast, the neuroscience of driving. Well, today's podcast, the neuroscience of driving. Well, let's start with the basics. Driving a car requires you to process the world around you, and at the same time, use your hands and feet to control a machine. And of course, you need to respond to things in the world, pedestrians, others' cars, light stop signs, bends in the road, etc. So how do we do it? Like, how does your brain handle this? It's actually a fairly complex problem. Probably not as complex as flying a helicopter, but it's still pretty challenging. Well, we've talked about vision in the past, and that is the primary sense that we rely on for driving. And yes, hearing does come into play,

someone honks their horn horn and things like this, but generally driving is heavily dominated by vision. Now, visual information comes to us through our eyes, of course, and we have previously discussed that information flows, in a sense, to the brain, to the back of our head where the primary visual cortex is located. But the flow of visual information is not a non-stop process. Indeed, in the middle of the brain, there are a collection of nuclei, for instance, the pulvinar nucleus. The pulvinar nucleus itself is a collection of nuclei. And just as a reminder, a nucleus, for clarity, is a collection of or a group of neurons that all have a common purpose.

a collection of or a group of neurons that all have a common purpose. So within the pulvinar nucleus, there are these other nuclei that play a role in visual processing. The lateral and inferior pulvinar nuclei basically pass visual information from the eyes to the early visual areas of the back of the brain. So they're like a transit station in a sense. However, the dorsal part of the latter pulvinar nucleus projects directly to the posterior parietal cortex. And this is important because the posterior parietal cortex plays a really crucial role in attention. So you can see how the lateral pulvinar nucleus is crucial for driving. It helps us direct our attention very quickly when we're needed. So, you know, imagine a pedestrian leaps out in front of you or someone, you know, puts on their brake lights and you see that or, you know, you have to react to something. Well, the lateral

pulvinar nucleus very rapidly is helping us direct our attention to the appropriate thing. And that's not all. The medial pulvinar nucleus has connections to motor regions amongst other places. And this is what allows us to very quickly, indeed, pre-consciously prepare to act if we need to. So in sum, as we're driving along, the pulvinar nucleus is crucial. It is going to help us orient our attention to things that might be important, like a pedestrian, like I said earlier. And it's also going to help prepare the motor system in case this does happen. And that is all before we're consciously aware of what's going on. So this is kind of cool because this is like the subconscious part of your brain,

or at least the subconscious visual part of your brain, helping you drive a car. of your brain, or at least the subconscious visual part of your brain helping you drive a car. But to be clear, it's only leading conscious awareness by 100 milliseconds or two, so it's not like it's doing it a couple of minutes in advance to help you out. Now, the pulmonary nucleus is not the only cool nuclei involved in driving. The superior colliculus is another midbrain nuclei that is in the visual flow pathway as well. And its job is to help direct the eyes towards things that are deemed to be important at a very low level. So once your attention is captured, you got to orient your eyes in the right direction. And that's part of what the superior colliculus is helping you do.

Think of things jumping out at you, or that simply grab your attention because they pop, while the superior colliculus is going to take your eyes and take control of them and effectively steer them to where they need to be. Now I'll briefly mention one of the other midbrain nuclei involved in vision, and that is the lateral geniculate nucleus. Basically the LGN is involved in early visual processing, which of course is also important for driving, is this is the processing that allows us to identify objects like other cars and stop signs. So visual information leaves the LGN and it goes primarily to the primary visual cortex, but the early

processing has already begun to help you consciously comprehend what's going on. Now I don't want to spend too much time on the primary visual cortex and the assessing has already begun to help you consciously comprehend what's going on. Now, I don't want to spend too much time on the primary visual cortex and the main visual system, because we covered that in detail back in season one. But in brief, the primary visual cortex basically tries to build up an understanding of the information that's there. So your eyes see the world, and that's projected back to the primary visual cortex. But your brain has to extract features from this. So it has to figure out, you know, what you're looking at. So you, in the PVC and other early visual areas, you know, you're extracting color and shape. And that just sequentially builds up until you identify the object.

Now, from the primary visual cortex, visual information flows. All right. So what we call visual streams. One route goes to the primary visual cortex, visual information flows, all right? So what we call visual streams. One route goes to the inferior temporal cortex, which is basically our perceptual system, and it's what allows us to identify things. And then another route goes to the parietal cortex, which is our vision for action, our ability to compute where things are in space relative to the body, amongst other things. And again, we covered those two visual streams in considerable detail in season one, so I'm going to stop there. But I will add in a fun driving fact. Have you ever been in a car and thought you were rolling

back when in fact the car was still? If this has happened to you, this is because your visual system was tricking you. For this to occur, the car beside you would have to begin to move forward. you. For this to occur, the car beside you would have to begin to move forward. And it also has to depend or does depend on what you're looking at. Typically not staring at the surrounding world, but you're looking at something in the car. And that's when your visual system detects the car moving beside you, but it gets tricked and it interprets the wrong way and tells you that you're moving backwards. And this is because, of course, your proprioceptive system, for the most part, doesn't detect that you're moving quickly in a car. So when you're sitting there and stationary in a car and the car interior is stationary around you,

your proprioceptive system isn't helping you out too much. So your brain believes the visual scene that's caught out of the corner of your eye, and it sends an alert that you're rolling back when you're not. The proprioceptive bit is also while it feels like you're stationary when you're on a plane for the most part, you're stationary relative to a large object that's around you, the plane, even though you're flying through the air at a really fast speed. But this isn't the neuroscience of flying, this is the neuroscience of driving. So let's get back to driving. Now, did I also mention the posterior parotid cortex? Yeah, we've talked about that in the past too. But just as a reminder, and I said

this a little earlier in this podcast, but this region plays a role in visual processing, like we've just reviewed, but it also plays a role in attention. We hinted at that in terms of the projections from the midbrain. But basically, in a quick review, there are two types of attention, global and focused. Global attention is our awareness of the world around us. Obviously, this is crucially important for driving. We have to be aware of everything in the world around us, and that's what the posterior parietal cortex is helping us with. But it's also helping us with focused attention, which is equally important. If you see a pedestrian on a curb, you might want to put your spotlight or your focused attention on them in case they do decide to step out. So the PPC plays a massive role in driving. And another driving fun fact, have you

ever driven somewhere and basically realized you do not really remember much about the trip? It's kind of like you got home on autopilot or got downtown on autopilot. Well, this again is tied to attention. Your attention system is processing information so you can drive, you know, pedestrians, other cars, bends in the road. But at the same time, unless something's really memorable, the attentional system isn't using its ties to your memory system to say, hey, maybe we should hold on to this. It's basically just discarding it and saying this isn't important. And this is why a routine drive home is quickly forgotten. But if you drove by an accident,

you might hold on to more details about the trip. Indeed, this is the same reason we forget a lot about our day. If you're just going through the motions for a day and you're doing your job and nothing stands out, your attentional system is basically not saying that anything important is happening. Everything's kind of ho-hum. So your brain just discards the information. I'm sure you've noticed this in the past. I know that sometimes I can finish teaching a lecture in front of a hundred students and I can get back to my office and go, you know,

did I just do that? Like what, what happened? I kind of, you kind of vaguely remember it, but you know, not a hundred percent. Well, that's your attentional system. Attention is also the reason while talking on your cell phone or texting while driving is a really, really bad idea. Basically, another way to think of attention is that it's a resource and you only have so much of it. So if something requires more attention than you have, then performance is reduced for a number of reasons. You might miss that pedestrian standing on the side of the road, for instance, or you might be slow to react to something and not engage your motor system in time. So this is why talking on

a cell phone is a bad idea and texting is a really bad idea. Texting not only takes your eyes off the road, which of course means you can't see things, but it also requires significantly more attention, leaving less for driving. You're using more than you have resources for. But what is even more interesting, should we have laws about talking to the person beside you? Because it's potentially the same problem. If you're having a super engaging conversation with the person beside you, you still don't have enough resources to focus 100% on driving. Or on a hands-free device, you know, you're still talking, which is actually the part that requires attention. Or eating, you know, if you're eating while you're driving, taking a sip of your coffee, that does take attention. Or eating. You know, if you're eating while you're driving, taking a sip of your coffee, that does take attention. Now, all these activities also require attention. So in principle,

should they all be illegal? I don't know the answer to that question, but I want you to think about that because they all pull attention. Now, onto the motor system. Two big things to consider. The act of just manipulating the steering wheel is a continuous task. For that, the motor system relies on the premotor cortex, which helps the motor system integrate visual information from the PPC and other regions with movement. And that's for an externally guided action like steering. And what I mean by that is steering is a response action in a sense. The road has got curves and you are moving the wheel back and forth and that's the premotor cortex. However, the discrete movements that we do like push on the brake, they're the province of the supplementary motor area, which is also integrating information

from the visual system to control what are called internally generated actions. And again, what I mean by that is that's something that you initiate and isn't driven by the outside world. Now, because it kind of is initiated by the outside world. Now, because it kind of is initiated by the outside world as well, the reality is that the supplementary motor area and the premotor cortex work together to help us drive and also other motor regions like the cerebellum. And if you want more information on the motor system, you can go back to season one again for the episode called Grabbing an Apple. Driving, sad fact. All of what I've been talking about is why driving under the influence of alcohol or drugs

is a bad idea. Alcohol and drugs basically slow your brain down. They slow down perceptual processing. They slow down attentional orientation. They slow down the motor system. So when you're under the influence and you're driving, that's why you don't respond as quickly. So when the person in front of you puts on their brakes suddenly

or the pedestrian that I keep talking about steps out, you're more likely to be in an accident and seriously hurt them or kill them even. So never drive under the influence of anything for any reason. There's another interesting note here, which is my lab has done a lot of work about cognitive fatigue. I talked about it on a previous episode. But cognitive fatigue is basically that state when your brain is tired and you start to make mistakes. Well, here's something interesting. When you're cognitively fatigued at a certain point, it's the same as being under the influence of alcohol. So again, should we have laws that

say if you're too tired, you shouldn't be driving? Because the reality is your brain is in the same state as if you were under the influence. All right, that's quite a bit on the neuroscience of driving. I hope you found it interesting and enjoyed it. I'll apologize one more time. Matt and I had to take a mid-season break last week. We just had a lot going on with work. I had to travel for a conference. Matt was busy doing some stuff, so we're a little bit behind. We're not going to try to catch it up. We're just going to go with that as a mid-season break, and we're just going to get back on track and release this podcast on sunday today and i'll be back on wednesday for another neuroscience bite now remember that neuroscience guy.com there's links

to patreon where you can support us it's really crucial and thank you to the people that are all the money goes to graduate students in the kregolson lab and there's our etsy store we have a new t-shirt coming out this week it's's called the Neuroscientist in Training shirt. I think you get the idea. I think it's kind of fun. I intend to get one because I don't take myself too seriously sometimes. Remember, you can follow me on Twitter

at that Neurosci guy. You can send questions or requests. The podcast next week is a request from the audience. It's going to be on attention deficit disorder. And of course, please subscribe to the podcast. Thank you so much for listening. My name is Olof Kregolsen, and I'm that neuroscience guy. I'll see you on Wednesday for another neuroscience bite.