That Neuroscience Guy - The impact of heat on the brain with special guest Dr. Coehoorn from Louisiana State University

Episode Date: July 24, 2022

We've all experienced those hot and humid days when our brains seem to work slower. Some people, like firefighters, face extreme heat regularly but still have to act rapidly in dangerous situations. How does extreme heat affect our brain, and what can we do to prevent that? In today's episode of That Neuroscience Guy, we invite a special guest Dr. Cory Coehoorn to tell us about the impact of heat on the brain. 

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. On today's episode, I've got another guest. It's Dr. Corey Kuhorn from Louisiana State University. Dr. Corey Kuhorn from Louisiana State University. And he's doing some really cool research looking at the impact of heat on the brain. Now, I've known Corey for a while now.

He used to be a PhD student here at the University of Victoria, but he's gone off and started this super cool lab that I want to tell you a bit about as well. But let's just dive right into it. So, Corey, thanks for being on the podcast. Thanks so much for having me. I appreciate it. So Corey, thanks for being on the podcast. Thanks so much for having me. I appreciate it. My pleasure. So tell me, tell us about your work with heat in the brain. So mostly what I've done is I've done work with firefighters and I've wanted to evaluate what is the impact of heat stress, but more specifically, what is the impact of rapid heat stress on the brain? So one of the things that I've looked at is, is there a difference in EEG or in decision-making capability when we heat someone

up quickly or whether or not we heat them up slowly? And what we've found is that heating someone up quite rapidly causes some decision-making issues. Oh, that's okay. So you're heating someone up rapidly. So I guess, cause you said firefighters, the idea would be that would be a firefighter going into a burning building that would cause a rapid increase in heat. Yeah. So typically what happens is firefighters, they'll get the call. They will head into, you know, head to the fire, head to the site of the fire. They will go in the fire. But one of the major issues that they have is that when they enter a house or a burning building, the, the ambient heat is actually quite intense.

Very, very, very hot. Uh, but also the personal protective equipment that they wear causes them to heat up even more. So what the personal protective equipment does is it protects them from the actual fire itself, but it doesn't allow heat itself to escape from the body. So these individuals, they start sweating, they start accumulating heat, and that heat is ultimately stored because we as human beings, especially adult human beings, the main way that we thermoregulate is we sweat and that sweat evaporates into the external environment. Well, that becomes a problem when these individuals

are wearing their personal protective equipment because the personal protective equipment doesn't allow the sweat itself to evaporate. So basically they're going into a really hot environment and normally if, if, like, if he said they were outside in the desert, you'd be sweating and that'd be evaporating, but they can't do that because they've got to wear the suit, which is trapping everything in. Exactly. It creates a microclimate and that microclimate has its own temperature and relative humidity. It's, it's similar to, you know, being that I'm, I'm in Louisiana and the humidity levels in Louisiana are extremely high. And one of the things that

people complain about, uh, in Louisiana is they explain, is they complain about the fact that when they go out and exercise, when it's really hot and really humid, they can't seem to cool down. Well, the humidity in the air actually also acts to create a tough situation as well where the sweat itself cannot evaporate. Okay, that's really cool. I want to come back to that, but let's stick with the firefighters for a little bit here. So you said it impacts their decision making. Can you expand on that a little bit? Yeah. So, you know, as you know, we as human beings, we make two major types of decisions. We make either system one or system two decision making. System one, more like gut hunch decisions,

you know, decisions that we would make really without even thinking. And then system two are more complex decisions where, uh, you might, there may be some sort of cognitive processing. What we found is that when you heat someone up and especially if you heat someone up quickly, it compromises their system to, uh, processing. So we've specifically looked at, uh, we've done some, uh, we've looked at the, at the theta band and we found that the theta band is actually compromised in a rapid heat stress scenario. The theta band is actually correlated strongly to cognitive control. If theta activity, especially frontal theta activity, is compromised, it causes a decrease in cognitive control. Decrease in cognitive control results in compromised system two decision-making. That's so cool. So just as a reminder for all the listeners,

theta band or brain oscillations between four and seven Hertz, you typically measure it with brainwaves or EEG. And it's, as Corey's just said, it's, it's reflective of this system two decision-making. So that's kind of, it's kind of,'s kind of well it's it's it's amazing people can do these things so they're rushing into a fire it's super hot and their analytical decision making system is shutting down which means they're going to rely more on gut hunches which which may or may not be the best thing to do wow yeah like typically, typically gut hunch decisions, like especially firefighters who've been in the game for a long period of time, they can make a lot of gut hunch decisions because they've seen these scenarios. You know, they've seen almost every scenario on a regular, regular day almost. things go wrong. So for instance, someone, they go into the fire and they're doing all their regular things. Then all of a sudden a beam falls or a beam falls on another one of the firefighters

or something like that. Then all of a sudden they need to start to process, how am I going to solve this particular scenario that just arose? And that can result in some problems, especially if they're, if they're excessively warm. That, oh, wow. I was about to say, why does this type of research matter? But I think, well, obviously you're on the road to saving lives. Yeah. You know, bottom line is, is we've, we've identified a problem. We've identified that decision-making is compromised, especially the system two decision-making. And this doesn't only relate to firefighters. Yes. This will allow firefighters, you know, their, their own lives to be saved, but also the individuals that they're trying to save.

But this whole concept and one of the things, one of the areas that I'm going down is I'm going to, I'm starting to work with the Air Force Base or the Air Force in the U.S. as well. And they have individuals like who do bomb disposal. They're called DOD individuals and are, sorry, EOD individuals, and they wear bomb suits. Well, again, those bomb suits can create these rapid heat stress scenarios. And you can imagine that if someone's trying to diffuse a bomb or, or, uh, prevent a bomb from exploding, they want to be able to access that system too, uh, as much as possible in order to, again,

able to access that system too as much as possible in order to, again, save their own lives or the individual's lives around them. Well, yeah, I was just thinking there's probably a lot of walks of life where people are in that kind of protective gear and this could be threatening. So you mentioned earlier that, you know, in Louisiana, it's extremely hot and humid. So I guess the question that, you know, reaches out is if you're in a hot human environment, is your decision-making compromised at least a little bit, maybe not the same extent as a fire, but to some extent? Yeah, it can be. The problem is, is when we're in a excessively humid environment, it actually behaves similar to what a fire suit or what a bomb disposal suit would in that it prevents, it's called an uncompensable heat stress scenario. Your body

cannot actually compensate. So you cannot maintain that 37 degrees Celsius core temperature. So the humidity itself in the environment creates a non-optimal water vapor pressure gradient and the sweat itself cannot evaporate and therefore you store heat, which could compromise decision making. Gotcha. So I guess the take home version is that in these hot humid environments that the actual environment is sort of acting like a suit. Not quite the same, but to some extent. Well, there you go. Some practical advice, I guess. If you're making decisions in hot human environments, maybe you should double check your process.

Have you thought about ways to offset the impact of heat on the brain? Like you said, the suit itself is creating a bit of the problem. Have you given some thought to what we could do to make things better for firefighters and other people in these sort of environments? Yeah, I've actually been working on several things. I'm collaborating with a couple of universities down in the U.S. to create something called a firefighter smart suit. And this firefighter's smart suit will actually give real life feedback to the firefighters and also to the fire commanders and allow them to actually have a good sense of where they are from a heat stress standpoint, from a heart rate standpoint. And

ultimately what that can do is allow the individuals themselves to pull themselves out or the fire commanders to pull themselves out, and which would ultimately allow for the firefighters who are in the scene to, um, to be optimal, right? They'll be able to make decision-making or proper decisions being that they won't be excessively warm because they'll have been pulled out of the fire. Another thing that I'm actually currently working on as well, and I'm, it's patent pending at the moment, but I'm actually working on a cooling suit, and it's patent pending at the moment, but I'm actually working on a cooling suit for firefighters as well. And what this will do is allow, you know, once the individuals start to heat up, we can actually cool down that microclimate, which will again, protect the firefighter from that excessive heat stress, which will ultimately

protect decision making ability. That's so cool. So a suit that actually cools you down. Obviously, you know, it's designed specifically for that environment. The last time I was down in the Southern United States, I wish I had something like that. Although I imagine it's not something you can walk around in. Do you have any other projects you'd like to share with us? Yeah, so we've recently just got grant funding for a project that will allow us to take our initial research, which looked at the immediate impact of rapid heat stress on the brain. And we're actually going to look at how long is that decision-making and frontal theta band compromised. So we're going to analyze these individuals post-rapid heat stress for 24,

48, and 72 hours post to see if their decision-making, if their frontal theta band is compromised during that period. So we're looking at more of, you know, see if there's more of a chronic impact. Yeah, not the acute effects, but the longer-term effects of this. Not the acute effects, but the longer-term effects of this. Exactly, yeah. Cool. Is there anything else you'd like to share with us? Tell us a bit about your lab, a bit about yourself. Yeah, so my name is, as you mentioned, my name is Corey Kuhorn.

I'm an associate professor in the kinesiology and health science department at Louisiana State University in Shreveport. And I'm also the human performance lab director. And in our human performance lab, we have an exercise physiology slash occupational physiology lab. We have a motion analysis lab. And then we also have a motor behavior lab as well. And it's pretty cool. It's a brand new lab and it's just kind of starting to, to, to come up. Um, we've really, really started to, uh, again, look at the brain. We've looked at heat stress, but we're also doing some other projects. We're doing a project with Stanford right now, looking at the genetics of, of elite aerobic fitness. So it's really been a cool opportunity to be the director there. And it's really exciting time. Yeah, no, I know a lot about your lab from, you know, chatting with you and just what I see. Well, thank you so much for being

on the podcast. It's really cool stuff. For everyone that's out there, just the summary, as I always do, is just the idea is simple. If you apply cute heat to the brain, you're going to impact your analytical decision-making and you're going to rely more on gut hunch decision-making in the case of the work that Corey's doing, you know, this could literally impact the lives of firefighters, as in they could be in dangerous situations and their brains not doing what they would like it to do. Corey, thank you so much for being on the podcast. Thanks so much for having me.

And a special thank you, because you might have heard that Corey's audio has been a little bit tweaky, but that's because he's such a dedicated neuroscientist that he's coming to us from a camping vacation in the middle of Alberta. So thanks for taking the time to do that. For everyone out there, of course, just remember,

we're just about to wrap up season three. We've got one more episode next Sunday and one bite in between. Remember that if you've got ideas for season four, please DM me on Twitter at thatneuroscienceguy. You can also email us at thatneuroscienceguy.com and check out the website at thatneuroscienceguy.com and check out the website at thatneuroscienceguy.com. You can buy t-shirts from a RETZI store. You can support us through Patreon.

And of course, thank you so much for subscribing. My name is Olaf Kregolsen and I'm That Neuroscience Guy. I'll see you on Wednesday for another neuroscience bite.