What does this look like to you?
To me it looks like a female face tilted back to take a big whiff of something—presumably, the fresh, pleasant-smelling air of Paris’s underground metro system (of course I’m being entirely facetious; it is often quite the opposite).
Why is this relevant? Let me explain.
One day on the way to class, out of boredom I was perusing the exciting advertisements plastering the walls of the metro car. My eyes landed upon this intriguing logo, accompanied by the letters, “RATP,” and I found it to be one of the most unintentionally amusing things that I have ever seen.
You see, in class we have been discussing many experiments that use mice. Mice are really good at being the subjects of neuroscience experiments, it turns out. So the first thing that came to my mind was this sort of double entendre: this poster was advertising the Paris metro system while highlighting the scent of rat urine that may often accompany it.
The symbol and acronym actually represent Régie Autonome des Transports Parisiens, the group that operates much of the public transportation in the region. And according to one website, the logo is supposed to be an artistic representation of Paris. I never would have guessed this, but perhaps my interpretation is unique, influenced by my recent experiences in class.
In fact, I’ve been thinking so much about rodents that I’ve been dreaming about them! So I wanted to know: Why was I dreaming about mice? Is it possible that these dreams impacted my interpretation of the RATP symbol?
My theory was that mice have been so prevalent in my thoughts during the day (due to all the neuroscience research that I have been reading about) that they infiltrated my dreams at night. Maybe this is what led me to interpret the logo in such a humorous way! Neuroscience can provide some answers as to what likely occurred here.
The neuroscience of sleep and dreaming isn’t fully understood. But, scientists know that the brain isn’t inactive when we’re asleep: contrary to the idea of “resting” during sleep, the brain actually doesn’t shut down at all (Debunking Sleep)! It fluctuates through different stages of activity throughout the night, meaning the cells are active in different patterns (Brain Basics).
During one type of brain activity called slow-wave sleep (SWS), our brains “replay” certain memories from the day and put them into long-term storage (Hasselmo, 1999). This is termed “memory consolidation,” and it is as if these experiences were being packaged into neat little containers for protection and easy access in the future. During “slow-wave sleep,” cells are sending signals in slow bursts, and this likely had a role in making my memory of the mice stronger and easier to recall! This strong memory of mice seems to be why I interpreted the RATP symbol in such a way. But what does dreaming have to do with it?
Dreams are created by the brain’s activity while we sleep. Scientists also know that their content—the scenes and emotions that get incorporated into them–is pulled from our recent thoughts and experiences while we’re awake (Stickgold et al., 2001). This explains why I was dreaming about mice!
But, my question isn’t fully answered yet: Was dreaming about mice what caused the memory consolidation that led to my humorous interpretation?
Neuroscientists actually don’t yet understand the relationship between dreaming and memory consolidation. But, some current research can help to shed some light on the subject.
A recent study by Siclari et al. (2017) identified a certain part of the brain they called a “hot spot” for dreaming. Whenever a certain type of activity is detected in this area—the back half of the brain, lying directly behind your ears—you are likely dreaming!
In order to do this, researchers used a machine called an electroencephalogram (EEG) to measure people’s brain activity while they were sleeping. Using sensors placed all over each subject’s head, this machine detects changes in electrical activity, telling researchers the patterns in which brain cells are firing (Britton et al., 2016).
In this study, people wearing EEG sensors (shown in the picture above) were awakened at random points during a night’s sleep and asked to report if they had been dreaming. By looking at the EEG data, the researchers were able to determine that high frequency activity—meaning that brain cells were sending signals very quickly—was associated with dreaming when it occurred in the back half of the brain. This means that they were able to predict whether someone was having a dream or not (Siclari et al., 2017)!
So what does that mean for me? The conclusions of this study suggest that dreams are actually less likely to occur during SWS, which is associated with low-frequency activity. Since this activity signals when memory consolidation occurs, it is not clear if dreaming about mice helped my brain consolidate the memory.
But, it’s still not clear if dreams have a role in consolidating memories. In the realm of neuroscience research, these findings are important, but they don’t exactly align with what has been suggested in the past. Some researchers have found that dreaming about an experience enhances one’s ability to recall it (Fiss et al., 1977; De Koninck et al., 1990; Wamsley 2014). Still, this is an essential step in understanding the mechanisms of memory consolidation in sleep: dreams likely have some functions that we haven’t fully uncovered yet!
In conclusion, it is still amusing to me how my daily experiences—solidified into my memory during sleep—shaped my interpretation of this advertisement in such an entertaining way! Certainly my experiences in class contributed a lot about rodents to my memory bank, and I’m grateful for it: If nothing else, it gives me an extra opportunity to chuckle to myself every day on an otherwise monotonous metro ride!
Brain Basics: Understanding Sleep. (n.d.). Retrieved from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep
Britton J.W., Frey L.C., Hopp J.L., et al. (2016). Electroencephalography (EEG): An Introductory Text and Atlas of Normal and Abnormal Findings in Adults, Children, and Infants. American Epilepsy Society. Available from: https://www.ncbi.nlm.nih.gov/books/NBK390346/
De Koninck, J., Christ, G., Hébert, G., Rinfret, N. (1990) Language learning efficiency, dreams and REM sleep. Psychiatr J Univ Ott. 15:91-92.
Debunking Sleep Myths: Does Your Brain Shut Down When You Sleep? (n.d.). Retrieved from https://www.sleepfoundation.org/articles/debunking-sleep-myths-does-your-brain-shut-down-when-you-sleep.
Fiss H, Kremer E, Litchman J. (1977).The mnemonic function of dreaming. Sleep Res. 6:122
Hasselmo, M. E. (1999) Trends Cogn. Sci. 3:351-359.pmid:10461198
Que signifie le logo RATP ? Creads décrypte ! Design Tribe. 06 May 2019. 17 June 2019 <https://www.creads.fr/blog/logos/ratp-logo-signification>.
Siclari, F., Baird, B., Perogamvros, L., Bernardi, G., LaRocque, J. J., Riedner, B., … Tononi, G. (2017). The neural correlates of dreaming. Nature neuroscience, 20(6), 872–878. doi:10.1038/nn.4545.
Wamsley, E.J. (2014) Dreaming and offline memory consolidation. Curr Neurol Neurosci Rep.14:433. doi:10.1007/s11910-013-0433-5.
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