Author Archives: Genevieve Wilson

A Glimpse Through Monet’s Eyes

Standing in Monet’s Garden in Giverny, I donned a pair of scratched, plastic-covered, yellowed glasses and watched the once-breathtaking view in front of me melt into a muddied and obscured version of its former beauty. As a class, we had taken a day-trip to explore the place that Monet painted his famous water lilies. Monet is thought to have had worsening cataracts as he aged, which

Monet’s garden (Personal image)

impacted his vision and therefore his artwork. To simulate his experience, in class we had made “cataract glasses” by altering a pair of safety glasses, and we wore them for part of our time in the garden. I sketched the scene, noting how the vibrant, defined foliage lost its form and beauty. Certainly, this distortion altered my perception and gave me a unique perspective. However, at the time, I did not consider my final product a very appealing result.

My Monet-inspired glasses, meant to imitate vision with cataracts (Personal image)

But, this representation of the scene wasn’t inherently bad, and being impaired didn’t necessarily make my depiction worse for its lack of accuracy! It may even be that “impairments” enhance creative ability: even with the failing functionality of his own vision, Monet was able to transform any scene into a masterpiece.

My sketch of the same scene without (left) and with (right) the glasses (Personal Image)

In other realms as well, what may be deemed an impairment may turn out to be neutral or even beneficial to an individual’s creativity or artistry! Perhaps surprisingly, recent research suggests that this may be the case for some dementia patients.

One study by Midorikawa et al. (2016) involved analyzing new or increased positive abilities that appeared in patients with behavior-variant frontotemporal lobe dementia (bvFTD) or Alzheimer’s Disease (AD). These types of dementia are the ones in which enhanced abilities—such as new or improved drawing, singing, or painting skills—are most commonly reported after disease onset, leading to an apparent boost in creativity or artistry.

First, to briefly introduce the diseases of interest: FTD and AD are both types of

The different brain regions affected by FTD and AD. (Image from ElderlyCareAssistance.info)

dementias, diseases in which brain cells begin to die. FTD is a rather rare type of dementia that begins early in life. Cells die in parts of the brain that deal with social skills, decision-making, and emotion—especially the front and the side (What is Frontotemporal Dementia?). The specific type called behavior-variant FTD (bvFTD) is characterized by changes in personality such as disinhibition, inappropriate behavior, and loss of empathy. (Kurz et al., 2014). AD, which is one of the most common types of dementia, usually begins later in life. A lot of the initial cell death happens in the hippocampus, a structure associated with memory, so memory problems are often some of first symptoms (Miller and Hou, 2004).

Some of the items from the questionnaire (Image from Midorikawa et al., 2016)

In this study, caregivers of people with FTD and AD filled out a questionnaire, ranking the patients on a variety of positive behaviors in three different categories: sensory processing, cognitive skills, and social/emotional processing. On a four-point scale, caregivers indicated the frequency of the listed behaviors in each category for their patient “before the illness” and “at the present time.” Prior to the study, each patient was also diagnosed by a neurologist and assigned a clinical dementia rating, or CDR. (Higher CDR numbers indicate a more advanced or severe stage of disease.) This would allow the researchers to see if there were differences in ability between various stages and types of dementia.

Study results: y-axis indicates the average score. X-axis indicates clinical dementia rating (CDR) for Alzheimer’s Disease or frontotemporal dementia. (Image from Midorikawa et al., 2016)

Subtracting the “before” score from the “present” score, the researchers obtained a representative value, where a positive number indicates more of the behavior since diagnosis. Averaging these values for each diagnostic rating, Midorikawa et al. (2016) performed a statistical test to assess the magnitude of change in that behavior. What they found was that some of these positive behaviors significantly increased after disease onset! In particular, they found that (as can be seen in the graphs below) both AD and bvFTD patients actually exhibited more language-related activities–meaning creativity in self-expression through language–in the earliest stages of the disease. Additionally, a small portion of patients of both dementias experienced an increase in visuospatial activities, which includes things like being able to depict scenes through painting or drawing!

Although patients at later stages of the disease experienced decreases in these behaviors, it is a very intriguing finding that patients’ creative expression actually increased after disease onset. Moreover, there have also been many case reports documenting increased artistic output following neurological damage due to other causes, such as traumatic brain injury, Parkinson’s Disease, and semantic dementia (Midorikawa and Kawamura, 2015; Canesi et al., 2016; Hamauchi et al., 2019). Just like with Monet, it appears that what appears to be a deficit may in reality not be quite so detrimental to the creative process!

One strength of this study was how all patients underwent a comprehensive neurological evaluation by the same experienced neurologist. This was effective to confirm the diagnoses of the patients using consistent parameters and to assess disease severity. However, being survey-based, these measures were quite subjective and may not be entirely accurate. What it contributes to the field, though, is that it is one of the first studies to systematically analyze these changes in artistic ability: others have primarily been case studies of individuals. The study also offers a unique perspective: most work on dementia serves to analyze the deficits that occur due to cell death. This study, however, highlights

Painting by one AD patient without previous artistic training or ability before disease onset (Image from Schott, 2012).

some positive aspects of the disease, contributing to a rather new initiative that is working to change the dynamic around mental impairments. Rather than viewing perceptual differences as incorrect or indicative of pathology, maybe we should allow ourselves to appreciate the creativity.

In sum, even though I felt a bit ridiculous in the moment, wearing my cataract glasses in Monet’s garden taught me a powerful lesson: A change in perspective is not necessarily bad, even when the conventionally beautiful scene undergoes some alterations in the process. Perhaps if more people would be willing to look a bit silly and try on some Monet cataract glasses, we could all come to appreciate those with neurological damage and perceptual differences a little bit more, valuing them for the unique perspectives they bring to the world.

 

References:

Canesi, M., Rusconi, M.L., Moroni, F., Ranghetti, A., Cereda, E., Pezzoli, G. (2016). Creative Thinking, Professional Artists, and Parkinson’s Disease. J Parkinsons Dis. 6:239-246. doi: 10.3233/JPD-150681.

Frontotemporal Dementia- Signs and Symptoms. (n.d.). Retrieved from https://www.ucsfhealth.org/conditions/frontotemporal_dementia/signs_and_symptoms.html

Hamauchi, A., Hidaki, Y., Kitamura, I., Yatabe, Y., Hashimoto, M., Yonehara, T., Fukuhara, R., Ikeda, M. (2019). Emergence of artistic talent in progressive nonfluent aphasia: a case report. Psychogeriatrics. 10.1111/psyg.12437.

Kurz, A., Kurz, C., Ellis, K., Lautenschlager, N.T. (2014). What is frontotemporal dementia? Maturitas. 79:216-219. doi: 10.1016/j.maturitas.2014.07.001.

Midorikawa, A., Cristian, L.E., Foxe, D., Landin-Romero, R., Hodges, J. R., Piguet, O. (2016). All is not lost: positive behaviors in Alzheimer’s Disease and Behavioral-Variant Frontotemporal Dementia with disease severity. Journal of Alzheimer’s Disease. 54:549-558. doi: 10.3233/JAD-160440.

Midorikawa, A., Kawamura, M. (2015). The emergence of artistic ability following traumatic brain injury. Neurocase. 21:90-94. doi: 10.1080/13554794.2013.873058.

Miller BL, Hou CE. (2004). Portraits of Artists: Emergence of Visual Creativity in Dementia. Arch Neurol. 61:842–844. doi:10.1001/archneur.61.6.842.

Schott, G. D. (2012). Pictures as a neurological tool: lessons from enhanced and emergent artistry in brain disease. Brain. 135:1947-1963. doi: 10.1093/brain/awr314.

 

Images:

http://www.elderlycareassistance.info/care-for-elderly-own-home/

https://academic.oup.com/brain/article/135/6/1947/327597

https://content.iospress.com/articles/journal-of-alzheimers-disease/jad160440

Hyperlinked videos and sites:

https://www.youtube.com/watch?v=fmaEql66gB0

https://www.google.com/maps/place/Fondation+Monet+in+Giverny/@48.9878008,1.6779037,9.68z/data=!4m5!3m4!1s0x0:0x77c5b6296865dff6!8m2!3d49.0753898!4d1.5337022

https://www.youtube.com/watch?v=yJXTXN4xrI8

https://www.youtube.com/watch?v=QuJFLr5Ib9k

Rodents on My Mind, Rodents on the Metro

What does this look like to you?

The RATP logo (Image from Creads.fr)

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.

Standard interpretation of the RATP symbolism (Image from Creads.fr)

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.

Lab rat (Image from Shutterstock.com)

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).

Electroencephalogram (Image from Michigan Advanced Neurology Center)

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.

Dreams of neuroscience experiments (Image from ScienceABC.com)

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!

References:

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.

 

Images:

https://www.creads.fr/app/uploads/sites/1/2017/06/xblog_header_logo-ratp.png.pagespeed.ic.i85aUDxX_m.png

https://www.creads.fr/app/uploads/sites/1/2017/06/xratp_paris-1080×360.jpg.pagespeed.ic.kCFNHediBC.jpg

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwiSkJfisfHiAhVEz4UKHaDuAhwQjRx6BAgBEAU&url=https%3A%2F%2Fwww.shutterstock.com%2Fsearch%2Flab%2Brat&psig=AOvVaw3hoyYBXrLGKLqHFqXyVCRE&ust=1560890866488329

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwjQzP_vsfHiAhXOxYUKHfERCY0QjRx6BAgBEAU&url=http%3A%2F%2Fdrmridha.com%2Fservices%2Feeg&psig=AOvVaw2kTv60u9LU2CwlYwZhFSf-&ust=1560890899835683

https://www.scienceabc.com/wp-content/uploads/2015/09/Happy-smiling-kid-sleeping-and-smiling-in-her-sleep.-Dream-the-little-princess-on-a-white-bed-close-up-speaking-in-dream.-Vitalinkas.jpg

Hyperlinked sites and videos:

https://www.ratp.fr/en/groupe-ratp

https://www.youtube.com/watch?v=I3j2VrhqTAA

https://www.youtube.com/watch?v=iWo90uxkNM0

https://www.creads.fr/blog/logos/ratp-logo-signification

Paul Cézanne, Museum Fatigue Advocate

Have you ever experienced museum fatigue? I thought that I made up this term to describe my own experiences, but upon performing a quick Google search, I discovered that this is actually a phenomenon first described in 1916 (Gilman, 1916).

Interior of the Musée d’Orsay (Image from TripSavy.com)

Going to a museum may seem like a passive process, but to me, it is actually quite a bit of work!

Navigating large crowds and carrying a heavy backpack for several hours is enough to wear me out. But even more so, interpreting piece after piece of artwork—each of which leaves a lot of room for interpretation—is a laborious effort leading to mental exhaustion. Though it is uncomfortable, I think that this is the way it should be. If you don’t experience some fatigue, are you fully engaged with and appreciating the art?

Exterior of Musée d’Orsay (Image from SortiraParis.com)

One particular French artist I have learned about in class is Paul Cézanne, and he seems to have been an especially avid proponent of museum fatigue; although his works were rejected from museums during his lifetime, it seems as if he were intentionally inducing this exhaustion. In the Post-Impressionistic style (abandoning the detailed, picture-perfect landscapes characteristic of Realism), Cézanne produced blurry, unfinished images in order to accentuate the mind’s interpretation process. Leaving blank spots peeking through the blobs of color is a technique called nonfinito, and it’s a bit like trailing off in the middle of a sentence—a visual ellipsis. In this way, the viewer’s interpretation is unique to the way the mind fills in the gaps at that particular moment, influenced by all of the emotions and experiences one brings to the table.

It turns out that this reflects how the brain works when interpreting all visual stimuli: even looking at the same things twice may trigger different responses from neurons dedicated to processing visual information (Jeon et al., 2018).

First, let’s start with some background information about vision and how our

The occipital lobe, shown in yellow (Image from The Science of Pscychotherapy.com)

brains process signals coming from our eyes.

Light enters the eye and reaches the retina at the very back. There, it stimulates light-responsive cells called photoreceptors (rods and cones). Signals from all these cells go through the optic nerve, the optic tract, a structure called the thalamus, and eventually reach the part of the brain that deals with visual information. This area is called the occipital lobe, and the section that is first to receive these signals is called the primary visual cortex, or V1. Here, there are cells that have been shown to respond to basic details of a scene like the width and orientation of lines (Gawne, 2015). Each cell is “tuned” to respond best to a certain width and a certain orientation, and logically, this is called neuronal tuning (Butts and Goldman, 2006). The conditions determining the responsivity of the neurons get more and more complex as the signals are processed (Tsunoda et al., 2001).

The perception of visual information (Image from Slideplayer.com)

As one views the same image, it would make sense that the same neurons respond each time. But, this is not exactly the case: In one experiment by Jeon et al. 2018 in the journal Nature, researchers found that the same neurons aren’t reliably activated by the same stimuli.

In the study, the researchers showed mice lines of different orientations and widths. Using a technique called two-photon calcium imaging, they looked at the activity of neurons in the V1 (Jeon et al., 2018). This technique involves installing an apparatus on the head of a mouse. Based on the movement of fluorescing ions, it lets us see what neurons are active as the mouse is awake and interacting with the world (Mitani and Komiyama, 2018).

Some of the images shown to mice in the Jeon et al. (2018) experiment (Image from the journal Nature)

Tracking around 300 neurons, the researchers determined the qualities of the image (such as the angle and the width of the lines) for which a neuron was most likely to respond. Then, performing the test one week later and again two weeks later, they compared the preferences of the neurons. While the majority of individual qualities were relatively stable over time, the researchers found that fewer than half of the neurons had exactly all of the same preferences as before.

What does this all mean? In the past it has been shown that the visual cortex is highly plastic, or able to rearrange and reorganize its connections based on new information (Hofer et al., 2009).  However, these results provide even more insight into how our visual systems adapt and change: some parts can remain stable while others change their responsivity in order to incorporate new information, altering our perception of the world around us.

So, our perception of static scenes is actually not static at all; it is being altered constantly! That boulangerie we pass on the way to class is not perceived by our brains in exactly the same manner every day.

Portrait of a Woman by Paul Cezanne (Image from the Metropolitan Museum of Art)

That leads me to wonder: especially when looking at one of Cézanne’s paintings—since he left so much for the viewer’s mind to fill in—do we ever experience the same thing twice?  This may very well be the most intriguing thing about his work, making it both timeless and malleable. A perfect excuse to visit the Musée d’Orsay just one more time.  The unfortunate result is only that this “museum fatigue” may become an increasingly common affliction. However, it’s likely already a common experience for all the museum-goers of the world, and I’m not afraid. It certainly won’t deter me from absorbing all of the Post-Impressionism art I can while I’m here!

 

References:

Butts, D.A., Goldman, M.S. (2006). Tuning curves, neuronal variability, and sensory coding. PLOS Biology. 4:92. doi: 10.1371/journal.pbio.0040092.

Gawne, T. (2015). The responses of V1 cortical neurons to flashed presentations of orthogonal single lines and edges. Journal of Neurophysiology. 113:2676-2681. doi: 10.1152/jn.00940.2014

Gilman, B. I. (1916). Museum Fatigue. The Scientific Monthly. 2:62–74.

Hofer, S. B., Mrsic-Flogel, T. D., Bonhoefer, T. & Hubener, M. (2009). Experience leaves a lasting structural trace in cortical circuits. Nature. 457:313–317.

Jeon, B. B., Swain, A.D., Good, J. T., Chase, S. M., Kuhlman, S.J. (2018). Feature selectivity is stable in primary visual cortex across a range of spatial frequencies. Nature. 8:15288. doi:10.1038/s41598-018-33633-2.

Mitani, A., Komiyama, T. (2018). Real-time processing of two-photon calcium imaging data including lateral motion artifact correction. Frontiers in Neuroinformatics. 12:98. doi: 10.3389/fninf.2018.00098

Tsunoda, K., Yamane, Y., Nishizaki, M., Tanifuji, M. (2001). Complex objects are represented in macaque inferotemporal cortex by the combination of feature columns. Nature Neuroscience. 4:832-838. doi: 10.1038/90547.

 

Image links:

https://www.tripsavvy.com/thmb/l0SeupBCtJWyVCf7U_I4BGsPql8=/960×0/filters:no_upscale():max_bytes(150000):strip_icc()/8414359797_20e28f27f2_o-56a403d25f9b58b7d0d4f0e6.jpg

https://www.sortiraparis.com/images/55/1467/108625-jeu-de-piste-gratuit-au-musee-d-orsay.jpg

https://www.thescienceofpsychotherapy.com/wp-content/uploads/2018/10/bigstock-Female-Occipital-Lobe-Brain.png

https://slideplayer.com/slide/6900016/23/images/4/Figure+4.1+%28a%29+Side+view+of+the+visual+system%2C+showing+the+three+major+sites+along+the+primary+visual+pathway+where+processing+takes+place%3A+the+eye%2C+the+lateral+geniculate+nucleus%2C+and+the+visual+receiving+area+of+the+cortex..jpg

https://collectionapi.metmuseum.org/api/collection/v1/iiif/656892/1571903/restricted

Hyperlinked videos and sites:

https://www.youtube.com/watch?v=fZDAwXh54is

https://goo.gl/maps/GM2ZURPTLpia3V7b9

https://www.paulcezanne.org/

 

Where is the Spicy Food in Paris?

On every street in Paris, there are three things you are certain to find: a boulangerie (or two or three), some sort of bistro/brasserie/café, and a Franprix (my personal favorite, a small-scale grocery store). Clearly, cuisine is central to Parisian life. And often, the options boil down to baguettes, wine, and cheese.

a typical boulangerie (“Savouries Counter – La Renaissance Patisserie” by avlxyz is licensed under CC BY-SA 2.0)

As a lover of spicy foods, I was at a bit of a loss. After about a week into my stay in Paris, I was ready to reintroduce some of the essential components of my normal diet—mainly, I’m referring to chili paste and other spices. Perusing the Franprix directly below my apartment, I was shocked to see that there was only one option for hot sauce. Not only this, but every café and restaurant I had been to showed no promise of the tongue-scorching, eye-watering foods I love. So I had some questions: why do I enjoy spicy foods so much? How are they registered in my brain? Is there a certain part of my brain—specifically for processing spicy taste sensations–that is more active for me than for a French person?

my chili paste from Franprix (Personal Image)

Before attempting to tackle any of these questions, let’s first explore how our brains perceive sensory information from the world around us.
The five basic senses–sight, sound, smell, taste, and touch–all have particular areas of the brain (in the bumpy outer layer called the cortex) devoted to receiving signals from our eyes, ears, nose, mouth, and skin, respectively. The area of the brain that registers taste is called the gustatory cortex.

Basic taste perception  (Image from Frontiers for Young Minds)

Nestled in taste buds scattered about the surface of the tongue, special receptor cells interpret chemical stimuli as sweet, salty, bitter, sour, and umami. From there, signals are sent to sensory neurons and into the brain through cranial nerves (Breslin and Spector, 2008). Spicy foods are detected a bit differently than other tastes, since these signals involve pain receptors (Immke and Gavva, 2006). But, recent neuroscience research has been determined that these signals still activate the gustatory cortex, so they count as a legitimate tastes (Rudenga et al., 2010)! Therefore, it seems that French cuisine is indeed missing an entire taste sensation, and it happens to be the one that is my favorite.

Taste bud (Image from LumenLearning.com)

Now that we’ve legitimized these piquant flavor sensations, let’s dive deeper into the neuroscience behind them.

While scientists still don’t understand exactly how taste perception works, it is clear that capsaicin (the chemical responsible for the spicy qualities of many of my favorite foods) actually results in unique brain responses. Unlike the other tastes, spicy sensations are often accompanied by the release of endorphins (explaining how they can be perceived as pleasurable) and activation of the autonomic nervous system. This unconscious system of bodily regulation is responsible for the perspiration, higher body temperature, and a faster heart rate associated with “hot” foods (McCorry, 2007).

In a 2015 study entitled “The Brain Mechanisms Underlying the Perception of the Pungent Taste of Capsaicin and the Subsequent Autonomic Responses,” Kawakami et al. (2015) investigated how these bodily responses happen after someone eats spicy food. The authors knew that the gustatory cortex (consisting of the middle and posterior short gyri, or M/PSG, of the insular cortex) must somehow be in communication with the brain area controlling autonomic system responses (the anterior gyrus of the insular cortex, or ASG). But, it wasn’t clear how this communication was happening.

In order to test this, the researchers administered three different taste solutions (spicy, salty, and neutral) to twenty human study participants. As the subjects tasted the solutions, the researchers took a look at their brain activity.
The method they used to analyze brain activity is called functional magnetic resonance imaging (fMRI). This produces high-resolution images of the brain while it is in action. Blood oxygenation level-dependent (BOLD) signals show where oxygenated blood is being used, indicating which regions are using up the most resources (Logothetis, 2003).

The ASG and M/PSG (Image from Frontiers in Human Neuroscience journal, Kawakami et al., 2015)

After performing this test, the researchers compared the brain images from the subjects. Their main findings were that there was coordination between the activity of the M/PSG and the ASG when people eat spicy foods. This could mean that these two brain areas are syncing up in order to produce symptoms like sweating and a quickened heartbeat after spicy food is consumed. Moreover, these results support the findings of another study done with mice, which concluded that cells in the ASG and M/PSG synchronize their activity patterns when capsaicin is tasted (Saito et al., 2012).
Kawakami et al. (2015) also found that the ASG was even more active than the M/PSG in response to capsaicin. Not only that, but both brain regions were significantly more active in response to capsaicin compared to the other solutions!

In sum, this study and previous work has helped to explain how the brain registers the taste of “hot” foods in the gustatory cortex and coordinates it with autonomic nervous system activation. However, the researchers only tested three taste sensations, and clearly, there is still much to be discovered about how the neuroscience behind gustation. Future work will likely take a closer look at the connection between the ASG and the M/PSG, possibly providing more insight into why some people (like me) find these mildly painful sensations more enjoyable than others.

   Baguettes are a staple in the                   Parisian diet (“Bag It” by Very Quiet is licensed under CC BY-SA 2.0)

In the meantime, perhaps knowing that eating spicy foods more fully engages the brain will inspire the French to literally “spice up” their diets and rethink that bland baguette, or at least offer more options in their grocery stores. That would make this hot sauce-lover very happy, and it would add a whole new dimension to French cuisine!

 

References:

Breslin, P.A., Spector, A.C. (2008). Mammalian taste perception. Current Biology. 18:R148-155. doi: 10.1016/j.cub.2007.12.017.

Immke, D.C., Gavva, N.R. (2006). The TRPV1 receptor and nociception. Seminars in Cell and Developmental Biology. 17:852-591. doi: 10.1016/j.semcdb.2006.09.004.

Kawakami, S., Sato, H., Sasaki, A.T., Tanabe, H.C., Yoshida, Y., Saito, M., Toyoda, H., Sadato, N., Kang, Y. (2015). The brain mechanisms underlying the perception of pungent taste of capsaicin and the subsequent autonomic response. Frontiers in Human Neuroscience. 9:720. doi: 10.3389/fnhum.2015.00720.

Logothetis, N.K. (2003). The underpinnings of the BOLD functional magnetic resonance imaging signal. Journal of Neuroscience. 23:3963-3971. doi: 10.1523/JNEUROSCI.23-10-03963.2003.

McCorry, L.K. (2007). Physiology of the Autonomic Nervous System. American Journal of Pharmaceutical Education. 71:78.

Rudenga K., Green B., Nachtigal D., Small D.M. (2010). Evidence for an integrated oral sensory module in the human anterior ventral insula. Chemical Senses. 35:693–703. doi: 10.1093/chemse/bjq068.

Saito, M., Toyoda, H., Kawakami, S., Sato, H., Bae, Y.C., Kang, Y. (2012) Capsaicin induces theta-band synchronization between gustatory and autonomic insular cortices. Journal of Neuroscience. 32:13470-13487. doi: 10.1523/JNEUROSCI.5906-11.2012.

Images (in order of appearance):

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwik5pOayNDiAhUFfBoKHRppA28QjRx6BAgBEAU&url=https%3A%2F%2Fwww.pagesjaunes.fr%2Fpros%2F05362487&psig=AOvVaw2ocJ8aEu44zmFV0LxJzoWx&ust=1559762799131578

https://kids.frontiersin.org/article/10.3389/frym.2017.00033

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwjZqu6RzdDiAhVZBGMBHaXYCI4QjRx6BAgBEAU&url=https%3A%2F%2Fcourses.lumenlearning.com%2Fwaymaker-psychology%2Fchapter%2Freading-taste-and-smell%2F&psig=AOvVaw1-_gpFcoSBHOxphR9YgJhr&ust=1559764284849243

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4717328/

 

Hyperlinked Videos/Sites:

https://youtu.be/TuVcnR5zAWo

https://www.youtube.com/watch?v=wGXoYippog8

https://neuroscientificallychallenged.com/blog/2013/05/what-is-insula