If the Heat waved, would you wave back?

1. Salut!

If you’ve read my first post, you already know I am not your common happy blogger… But don’t get me wrong, I LOVE PARIS and I’m having the time of my life!!!

So lets get started…

I landed in Paris a day before the start of the program, and stayed with my dad’s friend for a day. When I entered their house, I was shocked to see no central air conditioning unit, but I assumed they obviously have ACs in the bedrooms because isn’t it a necessity? Little did I know, ACs are not common in Paris, in fact, they are not “needed” because the weather is so pleasant. Coming from America, I guess you can say I am spoiled because I am used to being surrounded by air conditioning all day, everyday. From my home, to my car, to my school – it’s everywhere. Hence, I wasn’t consciously thinking of it as luxury but rather as a necessity.

Honestly, this is so relatable…

At Cite Universitaire, my room has a huge window that I normally keep open so that the temperature stays moderate, but even then I could not adjust to this non-AC lifestyle. After a few sleepless and irritated nights, I went and bought a fan; this was no doubt one of my best investments. That night, I slept like a baby.

The peaceful nights did not last very long though… This week, my third week in Paris, has been incredibly hot. The temperature went up the roof – about 35°C (95°F) average for the week. The authorities in France officially laid out precautions and plans to minimize the affects of this heatwave (thelocal.fr).

The temperature spiked around the 17th of June and returned to bearable temperatures on Friday!

As a person who already doesn’t like summer because of the unbearable heat, this was a very tragic week. I was sweaty, upset, annoyed, stressed, and tired all the time.

Those few moments of air conditioning or fan in some metros or restaurants were the moments I cherished. Coming back to my room everyday wasn’t something I looked forward to. Even my incredible fan wasn’t of much help with this heat.

With all these emotions and feelings I was going through, I wondered how this is affecting my brain (mainly because I needed a scapegoat to blame my unproductivity on – don’t judge).

As I dug deeper into the literature, I stumbled upon this article by Jiang et al. (2013) that investigated the effects of hyperthermia on human cognitive performance, using functional magnetic resonance imaging (fMRI), which is a technology used to detect changes in the brain activity during a specific task. Hyperthermia (HT) is defined as a condition in which the body temperature rises above normal. They wanted to see if cognitive performance would deteriorate in the HT condition compared to the control and how brain activity will be different in both groups.

The participants were divided into two groups; the HT group and the control group. To stimulate effects of hyperthermia, the HT group was in a hot chamber (50°C) with a thermal heated suit on for 30 minutes prior to the fMRI scanning. In the control group, the participants followed the same procedure but the chamber temperature was kept normal (21.5°C). The researchers precisely looked at brain activity during a visual short-term memory (VSTM) task to examine the participants’ cognitive performance. Previous research has shown three brain regions, dorsolateral prefrontal cortex (DLPFC), inferior intra-parietal sulcus (IPS), and intra-occipital sulcus (IOS), are involved in maintaining visual information for a short period of time (Todd et al. 2004, Grimault et al. 2009), hence, the researchers in the current study looked specifically at changes in activity in these three brain regions during the VSTM task.

In this task, the participants were presented with 60 trials of probe and target images, alternatively. Their task was to press “yes”, if the probe and target images were identical, or press “no” if the probe and target images were not identical. The participants in both the groups, control and HT, were in the fMRI scanner while they performed this task. Analyzing the behavioral results, they found that even though the HT group did not differ in accuracy compared to the control, they took much longer to answer the questions. On the neural side, fMRI results indicated increased brain activity in areas that are involved in visual memory task, as mentioned earlier (DLPFC and IPS). They saw that the brain was much more active during the heat exposure condition even though the participants were slow in the task, which shows that their visual short-term memory function was weakened. The researchers suggest that the increased brain activity could be due to more attention and cognition being used to do the same task compared to the control condition.

This study shows that exposure to very high temperatures, even for 30 minutes, can actually affect your cognitive performance. Your brain will need to use more energy and require longer time to perform a basic task. This study does an amazing job connecting the behavioral aspect with the neural aspect under heat stress in humans. It also uses well-defined brain regions, which makes it clearer to identify the changes in brain activity. However, they fail to discuss why they did not see changes in activity in IOS, one of the regions they evaluated during the tasks, even though previous research had shown that the IOS is involved in the visual memory task. More research needs to be done to identify how other cognitive activities may be affected due to heat, because global warming is a real problem and we see more and more incidents of heat waves occurring all over the world. If we better understand the impacts of heat on human brain and function, we can probably identify ways to prevent or rescue the damage caused by heat exposure.

Stay cool 🙂

Mehtab Manji

References:

Grimault S, Robitaille N, Grova C, Lina JM, Dubarry AS, Jolicoeur P (2009) Oscillatory activity in parietal and dorsolateral prefrontal cortex during retention in visual short-term memory: Additive effects of spatial attention and memory load. Hum Brain Mapp 30: 3378–92.

Jiang Q, Yang X, Liu K, Li B, Li L, LI M, Qian S, Zhao L, Zhou Z, Sun G (2013) Hyperthermia impaired human visual short-term memory: An fMRI study. Int J hyperthermia 29(3): 219-24

Local, The. “Paris: Authorities Trigger Emergency Heatwave Plan as Capital Continues to Sizzle.” The Local. The Local, 20 June 2017.

Todd JJ, Marois R (2004) Capacity limit of visual short-term memory in human posterior parietal cortex. Nature 428:751–4.

Images:

1, 4) http://www.welikela.com/heat-wave-memes-about-los-angeles/

2) http://www.funnycaptions.com/tag/summer-heat-jokes/4/

3) https://www.timeanddate.com/weather/france/paris/historic