Tag Archives: insula

From Cheese to Brain Structures

Four weeks into the NBB Paris program, I now know my friends in our apartment very well. In our apartment (maybe this applies to the others too), neither neuroscience nor soccer is the most discussed topic. This conversation is by far the most frequent. “What are we getting for dinner?” “I don’t know!” All of us are from different parts of the United States and even different parts of the world, which makes our restaurant selection processes a bit tricky. Nick Maamari, an Emory NBB senior from Dubai, thinks that cheese is the most disgusting food in the world. On the other hand, Daniel Son, a Korean-American student from Portland, Oregon, enjoys eating cheese so much that he bought a slice of gouda cheese from Monoprix on the first day we arrived in Paris.

France is a country known for its cheeses. In 1962, President Charles de Gaulle said, “how can you govern a country which has two hundred and forty-six varieties of cheese?” (Mignon, 1962) Being a neuroscience student, I ask, “what happened in Nick’s brain when he ate these French cheeses?”

Nick: “Eww*1,000”

Daniel: “the more it stinks, the better it tastes!”

Disgust has been identified as a basic emotion since Charles Darwin (Rozin and Fallon, 1987). Like other emotions, disgust has a characteristic facial expression (like the one shown in Nick’s photo), an appropriate action (Nick would definitely leave a restaurant if all available food has cheese), a distinctive physiological manifestation (nausea), and a characteristic feeling state (revulsion) (Rozin and Fallon, 1987). Research has found two brain structures that are considered as neural sites for processing disgust: insular cortex and basal ganglia (Sprengelmeyer, 2007). First, let’s start with some neuroanatomy.

(Byrne & Dafny, Eds.)

The insula cortex (or insula) lies deep within the lateral sulcus (as shown above) and it sits on an island (hence the name insular) covered with frontal, parietal and temporal opercula (“the lid”). It is interconnected with many cortical regions and subcortical structures, placing it at an ideal position to integrate homeostatic information with information about the physical and external environment (Sprengelmeyer, 2007).

(Henkel, 1998)

Basal ganglia is a group of subcortical nuclei responsible primarily for motor control and other roles such as executive functions, reward and emotions (Lanciego et al.). Two major neurodegenerative disorders, Huntington’s disease, and Parkinson’s disease are caused by the hyperactivation or hypoactivation of this structure, respectively (Cepeda et al., 2014). Previous research has identified cases where patients with Huntington’s disease were unable to recognize disgust (Sprengelmeyer et al., 1998).

Numerous research has shown the role of insula and basal ganglia in mediating disgust (Sprengelmeyer, 2007). However, most previous studies have focused on the recognition of facial expressions of disgust. The reason for the lack of research on food aversion is mainly due to a great variation between how each individual perceive what food is disgusting and also due to ethical issues associated with invoking uncomfortable feelings in experiments (Royet et al., 2016). A group of French researchers narrowed down their experimental food to … guess what, cheese (Royet et al., 2016). Cheese is loved by people like Daniel and hated by people like Nick, therefore, making it a great model to study the cerebral processes of food disgust.

In the first part of the study, the authors conducted a survey of the French population (this may be a biased sample and results do not apply to the rest of the world), to evaluate individual preferences for 75 foods and estimate the proportion of individuals who are disgusted by cheese. The authors have found a higher percentage (11.5%) of people disgusted by cheese than by other types of food. Now they have a study sample of individuals expressing a deep disgust for cheese.

The second part of the study involved Functional Magnetic Resonance imaging (fMRI), which is a tool to show activations of brain regions. The participants were asked to begin their experiments in a hunger state (these poor people did not even get a full breakfast) in order to make sure that the results were not biased by different metabolic rates after a meal. The researchers first presented participants in an MRI scanner with both the image and the smell of six different types of cheese and six other control foods. The participants were asked to judge whether the smell and sight of food are pleasant or not and whether they have a strong desire to eat the food.

After analyzing their data, the researchers found that global pallidus and substantia nigra (shown above) of the basal ganglia are more activated in people who dislike cheese. The authors also found that another structure of the basal ganglia, the ventral pallidum was inactivated in individuals disgusted by cheese. These structures are involved in what’s called the “reward pathway” of the brain, which regulates our perception of pleasure and facilitates the reinforcement of a particular behavior (Berridge and Kringelbach, 2015). Taken together, the authors proposed that perhaps a modified version of the pathway for encoding reward was involved when we were presented with food that aroused strong feelings of dislike. Interestingly, the authors did not observe any differences in activation of insula in people who like or dislike cheese.

One thing to keep in mind as you read fMRI studies is that “correlation does not imply causation”. A structure active for a task does not mean it is critical for the task. Also, conclusions made in papers generally involve heavy statistics and morphing all brains of the participants, who of course, have different brain shapes and sizes (Logothetis, 2008). Therefore, research results should be interpreted cautiously.

This study fills in some gaps in the research of disgust, specifically for food. It helps us understand the role of different parts of the basal ganglia in processing disgust. The null finding of insula also supports that insula has more complicated functions than simply processing disgust. A foundation of knowledge on this topic can be applied to a wide variety of eating disorders that affects many people in our lives. I would like to end with my favorite celebrity chef, Gordon Ramsay, who must have his brain structures associated with disgust constantly activated when judging his students’ dishes!

(Schocket, 2017)

Berridge Kent C, Kringelbach Morten L (2015) Pleasure Systems in the Brain. Neuron 86:646-664.

Cepeda C, Murphy KPS, Parent M, Levine MS (2014) The role of dopamine in Huntington’s disease. Prog Brain Res 211:235-254.

Lanciego JL, Luquin N, Obeso JA Functional neuroanatomy of the basal ganglia. Cold Spring Harb Perspect Med 2:a009621-a009621.

Logothetis NK (2008) What we can do and what we cannot do with fMRI. Nature 453:869.

Royet J-P, Meunier D, Torquet N, Mouly A-M, Jiang T (2016) The Neural Bases of Disgust for Cheese: An fMRI Study. 10.

Rozin P, Fallon AE (1987) A perspective on disgust. Psychological Review 94:23-41.

Sprengelmeyer R (2007) The neurology of disgust. Brain 130:1715-1717.

Sprengelmeyer R, Rausch M, Eysel UT, Przuntek H (1998) Neural Structures Associated with Recognition of Facial Expressions of Basic Emotions. Proceedings: Biological Sciences 265:1927-1931.

Byrne, J. H., & Dafny, N. (Eds.). Neuroanatomy Online: An Electronic Laboratory for the Neurosciences. Retrieved from Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston (UTHealth): https://nba.uth.tmc.edu/neuroanatomy/L1/Lab01p26_index.html

Henkel, J. (1998). Parkinson’s Disease: New Treatments Slow Onslaught of Symptoms. FDA Consumer, 17.

Mignon, E. (1962). Les Mots du Général.

Schocket, R. (2017, September 6). This Is The Disgusting Reason Gordon Ramsay Refused To Swim In A Hotel’s Pool. Retrieved from BuzzFeed: https://www.buzzfeed.com/ryanschocket2/gordon-ramsay-refused-to-swim-in-this-hotels-pool-because?utm_source=dynamic&utm_campaign=bfsharecopy&sub=0_11766940#11766940

Accents away from Accent

This weekend I went on a crazy, fun, whirlwind trip to London along with Shelby, Kendall, Jamie, Alyssa, and Merry. While we were only there for a day and half, we managed to see Buckingham Palace, Westminster Abbey, Big Ben, London Bridge, and most of the other major famous sites. As we raced all over the city in the underground, I kept accidentally saying “pardonne-moi” and “désolé” to everyone I bumped into. Only, for the first time in weeks, everyone around us was speaking English. But, even though we all speak English, the way that the locals around us pronounced words and phrases was still different than our own speech.


Of course, from the moment we arrived in England, we were sounded by English accents. Several of us found ourselves fascinated by these accents and, when we were safely out of earshot, we even did our best to imitate them. Yesterday morning as I sat on the train back to Paris, I decided to try to find out what it is about our brain that allows to recognize, use, and understand different accented versions of the same language.

Westminster Abbey

Determining exactly what parts of the brain allow us to understand unfamiliar accents is a difficult task, but there is a growing body of research on this topic. Many of the studies on accent comprehension use functional magnetic resonance imaging (fMRI) to detect changes in brain activity and as subjects listen to sounds or sentences in different accents (Ghazi-Saidi et al., 2015).

A recent review of this research and found that other researchers have identified areas like the left inferior frontal gyrus, the insula, and the superior temporal sulci and gyri as having higher activity when listening to accented speakers produce sounds (Callan et al., 2014; Adank et al., 2015).Interestingly, many of these brain areas are the same regions that have been identified as important for understanding foreign languages (Perani and Abutalebi, 2005; Hesling et al., 2012).Some of these areas that are important for understanding unfamiliar accents – including the insula, motor cortex and premotor cortex – have also been implicated in the production of these accents (Adank et al., 2012a; Callan et al., 2014; Ghazi-Saidi et al., 2015). 

Investigating the production of accented speech is also an exciting field of study. Interestingly, one of the main ways we have learned about accent production is through case studies of patients with Foreign Accent Syndrome (FAS). FAS is a fascinating motor speech disorder where patients speak in a different accent than they originally used, typically following brain damage (Keulen et al., 2016). This condition was actually first identified here in Paris by Pierre Marie¹, a French neurologist (Keulen et al., 2016). After recovering from a brain hemorrhage, Marie’s patient had an Alsatian French accent instead of his original Parisian one (Marie, 1907). Since then, nearly 200 cases of this rare disease have been identified (Mariën et al., 2019).

Pierre Marie

However, it is hard to draw conclusions from individual case studies with just one patient. In a recent metanalysis (a procedure where data from other studies is combined and analyzed), Mariën et al. looked at 112 different published cases of FAS to draw larger conclusions about this rare disease. The authors were particularly interested in cases of FAS that occurred after a stroke, but they analyzed case studies from patients with all different kinds of brain damage.

To review these cases, Mariën et al. first compiled published case studies that reported the cause and symptoms of a patient’s FAS from Pierre Marie’s case in 1907 through October 2016. They then calculated and analyzed the demographic, anatomical, and symptomatic features of these FAS patients to look for larger trends across the different cases.

The authors found that there are statistically significantly more female patients (68% of cases) than male patients in these 112 FAS cases. Additionally, a significant and overwhelming majority (97%) of cases were in adults. In more than half the patients (53%) FAS was present following a stroke.

For those patients who developed FAS following a stroke, the authors also analyzed where in the brain their vascular damage was. The most commonly damaged brain areas (60% of vascular FAS patients) were the primary motor cortex, premotor cortex and basal ganglia which are all important for the physical ability to produce voluntary speech (Brown, Schneider, & Lidsky, 1997). The authors also found that 13% of these vascular FAS patients had damage in the insula, an area that has also been identified as important for accented speech production in studies of healthy subjects (Ghazi-Saidi et al., 2015).

The Insula

I think FAS is a fascinating disorder, but is important to remember that, like any case studies, these reports have a limited ability to tell us about how healthy people produce accented speech. The naturally occurring brain damage in these FAS patients is not necessarily localized, and other brain areas besides for the primary lesion location could have been affected by the damage. Furthermore, there are some cases of psychological (as opposed to neurological) FAS which complicates our understanding of the onset of this disease (Keulen et al., 2016).

While there is still a lot to learn about understanding how we construct and comprehend accented speech. Studies of FAS patients, particularly large metanalyses like this one, have just begun to identify some of the key brain areas that are reliably indicated in accent production. These findings provide a good starting point for future researchers to analyze these brain areas further and possibly study their role in healthy patients’ accents, which can help us all understand each other a little better.



1 – As a side note for my NBB 301 classmates: Pierre Marie is the “Marie” in Charcot-Marie-Tooth disease, a glial disease that affects Schwann cells. He was also a student of Jean-Martin Charcot and was one of the people depicted in the famous painting A Clinical Lesson at the Salpêtrière that we saw at the Musée de l’Histoire de la Médecine today.



Westminster Abbey: taken by me

Pierre Marie: https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/PierreMarie.jpg/230px-PierreMarie.jpg

Insula: https://upload.wikimedia.org/wikipedia/commons/b/b4/Sobo_1909_633.png



Adank P, Davis M, Hagoort P (2012a). Neural dissociation in processing noise and accent in spoken language comprehension. Neuropsychologia50, 77–84. 

Adank P, Nuttall HE., Banks B, & Kennedy-Higgins D (2015). Neural bases of accented speech perception. Frontiers in human neuroscience9, 558. doi:10.3389/fnhum.2015.00558

Brown L, Schneider JS, & Lidsky TI (1997). Sensory and cognitive functions of the basal ganglia. Current Opinion in Neurobiology, 7, 157–163.

Callan D, Callan A, & Jones, JA (2014). Speech motor brain regions are differentially recruited during perception of native and foreign-accented phonemes for first and second language listeners. Frontiers in neuroscience8, 275. doi:10.3389/fnins.2014.00275 

Ghazi-Saidi L, Dash T, Ansaldo AI (2015). How native-like can you possibly get: fMRI evidence in a pair of linguistically close languages, special issue: language beyond words: the neuroscience of accent. Front. Neurosci. 9:587.

Hesling I, Dilharreguy B, Bordessoules M, Allard M. (2012). The neural processing of second language comprehension modulated by the degree of proficiency: a listening connected speech FMRI study. Open Neuroimag. J. 6, 1–11.

Keulen S, Verhoeven J, De Witte E, De Page L, Bastiaanse R, & Mariën P (2016). Foreign Accent Syndrome As a Psychogenic Disorder: A Review. Frontiers in human neuroscience, 10, 168.

Marie P (1907). Un cas d’anarthrie transitatoire par lésion de la zone lenticulaire. In P. Marie Travaux et Memoires, Bulletins et Mémoires de la Société Médicale des Hôpitaux; 1906: Vol. IParis: Masson pp. 153–157.

Mariën P, Keulen S, Verhoeven J (2019) Neurological Aspects of Foreign Accent Syndrome in Stroke Patients, Journal of Communication Disorders, 77: 94-113,

Perani D, Abutalebi J (2005). The neural basis of first and second language processing. Curr. Opin. Neurobiol. 15, 202–206.