Association for Chemoreception Sciences

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Press Abstracts

Associations Among Fatty Food Sensations, Diet, and Expectorated Emulsions
Li-Chu Huang & Cordelia A Running.
Purdue University, West Lafayette, IN, United States

Saliva influences chemical and textural sensations, yet details and sources of individual variability for these phenomena are still lacking. In this study, we investigated fatty sensations, dietary habits, and saliva’s emulsifying properties. Through a remote tasting and spitting protocol, participants were asked to discriminate among and rate sensory properties of fatty candies with varying concentrations of added linoleic acid (LA). Additionally, participants swished and expectorated an oil/water mixture, and the size of the expectorated sample’s fat layer was visually analyzed. Dietary habits were also analyzed. Sensory ratings of fatty candies indicate differences based on successful completion of a LA discrimination task. Successful discriminators showed increasing fattiness and a trend for increasing bitterness with increasing LA concentration. Unsuccessful discriminators showed only increasing bitterness with increasing LA concentration. No correlations were observed among sensory ratings and diet or expectorated emulsion fat layer size. However, at 0 sec, larger fat layers were observed for those with greater dietary protein intake, as well as for individuals who passed the LA discrimination task. At 30 sec, greater fat layer size associated with greater solid fat and protein intake. Finally, larger changes in fat layer size overtime associated with lower solid fat intake, and changes were greater in those who passed the LA discrimination task. Overall, results indicate dietary protein and fat associate with salivary emulsifying effectiveness, and that ability to discriminate fatty acid taste sensation may correlate with the sensory quality experienced from fatty acids.

Effects on growth of regular smell and taste of milk during tube feeding of premature infants: a randomized clinical trial.
Friederike Beker^1,2, Helen G Liley^1,2, Ian Hughes³, Sue Jacobs⁴, Emily Twitchell⁴, Judith Macey¹, Peter G Davis⁴
¹Mater Research Institute, South Brisbane, Australia, ²Mater Mothers Hospital, South Brisbane, Australia, ³Gold Coast University Hospital, Gold Coast, Australia, ⁴Royal Womens Hospital, Melbourne, Australia

Objective: Smells and tastes of food increase food anticipation, activate gut motility, and stimulate digestion and metabolism. Despite poor growth of many preterm infants in intensive care, smell and taste of milk with tube feeding is not generally considered part of their care. To determine the effect of smell and taste of milk with tube feeding on weight z-scores at discharge from hospital. Methods: Randomized, non-blinded, superiority trial. Eligible infants were born at less than 29 weeks’ postmenstrual age (PMA) and/or with a birth-weight of less than 1250g. Infants were randomly assigned to either smell and taste of milk with each tube feed or routine care without the provision of smell and taste of milk. Primary outcome was weight z-scores at discharge from hospital. Secondary outcomes included anthropometric measures at different time points, time to full enteral feeds and other health outcomes. Results: Infants were randomized to treatment and control groups:196 and 200 infants, 51% and 52% male, mean (standard deviation) PMA at birth: 27.5 (2.2) and 27.6 (2.3) weeks, respectively. Median (interquartile range (IQR)) weight z-score at discharge were -0.7 (-1.75 - -0.05) and -0.92 (-1.63 - -0.31), for treatment and control groups, respectively, p=0.40. All anthropometric outcomes had a trend towards better growth in the treatment group and the difference in median (IQR) head circumference z-score at 36 weeks’ PMA was significant: treatment -0.37 (-0.99;0.17) and control -0.61 (-1.26;0.09), p=0.04. All other feeding and health outcomes were not different between study groups. Conclusions: Regular smell and taste of milk with tube feeding improves some nutritional outcomes in very preterm infants. It is a simple and inexpensive intervention with no apparent adverse effects.

Individual Differences in Odor Naming and Odor Nameability
Sarah Cormiea, Pamela Li, Jason Fischer
Johns Hopkins University, Baltimore, MD, United States

Odors have no fixed size, shape, or spatial location. Even for very familiar odors, people often struggle to identify them by name. Here, in a series of three tasks, we investigated how odor naming ability varied across individuals. We also investigated how odor stimuli themselves varied in nameability. We devised an odor naming task to test participants’ ability to identify odors without any visual or context clues. This task involved smelling a set of 36 real-world odors (e.g., oranges, onions, coffee, baby powder, burnt matches, vanilla, grass) and trying to name them. Participants were allowed to make as many guesses as they wanted for each odor (they were asked, “Do you want to guess anything else?” after each guess). Participants were not given feedback about the accuracy of any of their guesses. The resulting data comprised a corpus of responses for each participant and for every odor in our set. To assess low-level olfactory performance, participants also completed an odor discrimination task in which they had to sniff two odor mixtures on each trial and rate them as the same or different. We computed their overall accuracy for odor discrimination ability as well as a d-prime score. Participants also completed the Kaufman Brief Intelligence Test (KBIT) to assess linguistic ability, non-verbal reasoning, and problem solving. Across two testing sessions, we found that some people were consistently better at identifying odors than others, even after controlling for odor discrimination and KBIT scores. Taken together, these results demonstrate that odor naming ability varies within a population and is not reducible to a collection of other cognitive abilities. And nameability is a unique and reliable perceptual property of odors themselves.

Modulation of the peripheral olfactory response by trigeminal agonists
Federica Genovese, Emylette Cruz Cabrera, Marco Tizzano, Johannes Reisert
Monell Chemical Senses Center, Philadelphia, PA, United States

The olfactory epithelium (OE) contains both olfactory sensory neurons (OSNs) and trigeminal fibers, one detecting odorants and the other irritants. However, it is unclear if these two chemosensory systems interact. Using electro-olfactograms (EOGs), we characterized responses to odorants with different trigeminal potencies in wild-type (WT) and knockout (KO) mice, which lack the chemosensory trigeminal receptors TRPA1 and TRPV1. The TRPA1 agonists, allyl-isothiocyanate (AITC), and cinnamaldehyde (CNA) showed reduced EOG responses in KO compared to WT mice. No significant differences were observed in response to the odorants pentyl acetate (PA), β-phenyl ethyl alcohol (PEA), both with low trigeminal potency, and the TRPM8 agonist, menthol. Furthermore, brief activations of peptidergic trigeminal fibers by strong trigeminal agonists (AITC and CO2) induced a progressive decrease of OSN responses to a pure olfactory stimulus (PEA). Such modulation is lacking in KO mice and also in the WT when stimulating trigeminal fibers with menthol. Interestingly, when stimulated with CNA or PA, moderate TRPA1 agonists, PEA responses in WT were increased compared to the KO. We conclude that irritants can modulate EOG responses. We determined that the trigeminal and olfactory systems interact in the OE, with the trigeminal system potentially having a bimodal modulation on olfactory responses. Strong trigeminal irritants cause a reduction of the odor response, while moderate trigeminal agonists might induce an enhancement. The relatively slow (minutes) temporal dynamics of the trigeminal modulation of olfactory responses, and the lack of any modulation by agonists of non-peptidergic fibers (menthol), suggest a mechanism of olfactory modulation mediated by TRPA1/V1 positive trigeminal peptidergic fibers.

Plasticity of Retronasal Odor Perception in Young Children
Sarah E. Colbert & Joost X. Maier
Wake Forest School of Medicine, Winston-Salem, NC, United States

Flavor perception is a key factor in dictating food choice, which directly relates to health outcomes such as obesity and type II diabetes. Between 2 and 6 years of age, children experience changes in food attitudes. This project examines the potential contribution of gustatory and and retronasal olfactory perception to these behaviors. Although taste preferences are stable from birth, there is no knowledge of the development of retronasal smell perception, partly due to the difficulty in assessing sensory function in toddlers. Thus, the primary goal of this study is to implement a novel protocol for assessing flavor preference in toddlers to investigate developmental changes in retronasal odor perception. Subjects were recruited and tested in the local community. Young children (n=22) and one of their parents (n=24) were asked to drink 8 solutions consisting of clear liquids with either a taste or an odor compound, or plain water. Solutions were presented in cups with lids and straws to prevent orthonasal recognition. Participants rated the solutions on a 1-5 pictorial liking scale, and reactions were recorded with a camera to assess facial/vocal responses. Stimuli consisted food and nonfood odorants. High concentrations of sweet and bitter tastes were used as positive control. Ratings from all solutions were analyzed to determine perceived flavor intensity and valence. We predicted that retronasal olfaction undergoes developmental changes, while taste remains stable. We found that taste intensity and valence, as well as odor intensity did not change, but there was more variability in valence ratings for odors in children compared to adults. This suggests that the subjective aspects of retronasal odor perception differ between children and adults and can potentially be modified by experience.

Cerebellar decoding accuracy of real and imagined odors is associated with odor imagery ability and food craving intensity
Emily E Perszyk^1,2, Jessica Trinh^1,2, Jelena Djordjevic³, Marilyn Jones-Gotman³, Hedy Kober², Dana M Small1²
¹Modern Diet and Physiology Research Center, New Haven, CT, United States, ²Yale University, New Haven, CT, United States, ³McGill University, Montreal, QC, Canada

Mental imagery plays a key role in the generation and intensification of food cravings (Kavanagh et al. 2005). Since self-reported ability to imagine odors varies widely (Bensafi & Rouby 2007) and correlates with BMI (Patel et al. 2015), we tested the hypothesis that people with better odor imagery ability experience more intense food cravings. Odor imagery ability, craving intensity, and neuroimaging measures were collected in 10 participants with a range of BMI (data collection ongoing). Odor imagery ability was defined psychophysically as the extent to which imagining the smell of one odor impairs peri-threshold detection of a different odor (i.e., the interference effect; Djordjevic et al. 2004). Craving intensity ratings were obtained across 90 palatable food images and averaged for each participant. fMRI measured whole brain responses as participants smelled and imagined rose and cookie odors. A machine learning classifier was trained to differentiate rose vs cookie using voxel patterns evoked during real olfaction. The classifier was then tested for its accuracy to decode rose vs cookie using patterns evoked during imagined olfaction as our neuroimaging measure of odor imagery ability. Linear regressions revealed a positive relationship between the interference effect and craving intensity, indicating that individuals who imagine odors vividly experience stronger cravings. Both the interference effect and craving were also positively associated with cerebellar decoding accuracy. This work establishes a relationship between odor imagery ability, food craving intensity, and the fidelity of the olfactory neural code between real and imagined odors in the cerebellum. We conclude that these interim findings provide preliminary support for the involvement of odor imagery in food craving.

Chemosensory Dysfunction in COVID-19: Behavioral and Neurobiological Factors
Shima T Moein¹, Richard L Doty², Valentina Parma³, Jonathan Overdevest⁴, Carol Yan⁵.
¹School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran, ²Smell & Taste Center, Department of Otorhinolaryngology-Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, ³Department of Psychology, Temple University, Philadelphia, PA, United States, ⁴Department of Otolaryngology – Head and Neck Surgery, Columbia University Medical Center, New York, NY, United States, ⁵Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of California San Diego Health, La Jolla, CA, United States

In early March of 2020, reports appeared in the social media of many countries linking smell/taste loss to the spread of SARS-CoV-2. Such reports led to studies of the prevalence and reversibility of the smell loss of COVID-19 and the cellular mechanisms responsible for the loss. These studies have the potential to play a significant role in early COVID-19 detection and the development of preventative interventions and therapies for COVID-19. In this symposium, the olfactory and gustatory manifestations of COVID-19 will be reviewed. Dr. Parma will discuss how a global consortium approached this issue in COVID-19 patients in over 60 countries. She will address the prevalence of chemosensory loss and its continued presence in various groups of patients. Dr. Overdevest will present the evolution in investigations to identify molecular pathways that are dysregulated during COVID-19 infection through a histopathologic and transcriptomic evaluation of post-mortem nasal epithelium biopsies.As the pandemic continues despite containment and mitigation strategies, even a low percentage of patients with sustained smell loss and other problems may challenge health systems. Dr. Yan will discuss the implications of smell loss, its assessment, and its management in the clinic. Moreover, challenges for clinicians to minimize its long-term effects on physical and mental health, including quality of life, will be addressed.Finally, Dr. Doty will explain how machine learning techniques are being used to optimize the sensitivity of smell tests to detect COVID-19. Such tests have the potential to provide a sensitive and inexpensive means for detecting persons carrying SARS-CoV-2 early in the COVID-19 disease process, as well as for tracking their function over time.

Modulation of Olfactory Output Neurons Affects Whole-Body Metabolism
Louis J Kolling¹, Roberta Tatti², Debra A Fadool^1,2,3
¹The Molecular Biophysics Program, The Florida State University, Tallahassee, FL, United States, ²Progam in Neuroscience, The Florida State University, Tallahassee, FL, United States, ³Department of Biological Science, The Florida State University, Tallahassee, FL, United States

The voltage-gated potassium channel Kv1.3 is a large driver of cellular excitability in the olfactory bulb (OB) and in peripheral tissues. Global Kv1.3-/- mice exhibit a “Super-smeller” phenotype, increased metabolism, and resistance to diet-induced obesity (DIO). Direct delivery of Kv1.3 blockers to the OB of wildtype mice confers an increase in metabolism, suggesting a relationship between olfaction and energy balance. We generated a conditional CRISPR knockout of Kv1.3 in mitral and tufted cells (M/TCs). With this, we circumvent peripheral and hypothalamic Kv1.3 contributions. We bred Tbx21-cre mice to floxed Cas9 mice and engineered single guide RNA (sgRNA) to be delivered using adeno-associated virus (AAV). Transduction patterns of AAVs 2, 3, 5, 8, and 9 were mapped; AAV9 showed the highest preference for M/TCs. Tbx21-Cas9-GFP progeny were then injected with AAV9-hSyn-mCherry-U6-sgRNA to achieve effective co-labeling of Cas9 and sgRNA (Mitral- 67%, Tufted- 32%). Whole-cell recordings were performed to compare MCs of Cas9+ (CRISPR mice) vs. Cas9- (control) littermates. On average, MCs of ‘CRISPR mice’ had a less negative resting membrane potential, and the current needed to evoke action potentials (APs) was lower. The APs of CRISPR mice have faster rise kinetics (time to peak, time to maximum slope) and slower decay kinetics, consistent with a loss of potassium channel conductance. CRISPR mice were resistant to DIO and glucose insensitivity vs control littermates, as determined by glucose tolerance test, in vivo NMR, and post-mortem fat pad analysis. CRISPR mice show increased odor discrimination in a habituation/dishabituation assay compared to control littermates. Our data show that CRISPR editing tools may be useful to link the enhanced excitability of OB output neurons to energy balance.

Molecular Transport Explains Which Molecules Are Odorous
Emily J Mayhew¹, Charles J Arayata¹, Richard C Gerkin², Brian K Lee³, Jonathan M Magill¹, Lindsey L Snyder¹, Kelsie A Little¹, Chung Wen Yu¹, Joel D Mainland1⁴.
¹Monell Chemical Senses Center, Philadelphia, PA, United States, ²Arizona State University, Tempe, AZ, United States, ³Google Research, Brain Team, Cambridge, MA, United States, ⁴University of Pennsylvania, Philadelphia, PA, United States

The number of molecules humans can smell is disputed, with published estimates ranging from 10,000 to infinitely many. Chemical space is vast, and we cannot resolve this dispute until we define the subset of chemical space that has an odor. We propose that molecules that can complete the transport process to reach olfactory receptors are generally odorous. Although physical transport is well-understood, a general classification model for odors has been elusive because the available data were both noisy and poorly curated. We generated a large and chemically diverse dataset of over 1,900 molecules, classified as odorous (84%) or odorless (16%) through a combination of literature- and web-scraping, human discrimination tasks, and chemical analysis. We additionally performed rigorous quality control on this dataset to correct errors in the data – both in odorous/odorless labels and in physicochemical features. When we used this quality-controlled dataset to train machine learning models, we found that features that drive transport of molecules to olfactory receptors (volatility and hydrophobicity) are sufficient to reliably classify novel molecules as odorous or odorless (AUROC = 0.97) and that use of additional molecular features does not significantly improve model accuracy. Applying our transport-based model to GDB17, a database of all possible small organic molecules (HAC ≤17), we estimate that over 30 billion possible compounds are odorous, 6 orders of magnitude larger than current estimates of 10,000. Remarkably, nearly all transport-capable molecules are odorous, suggesting broad collective tuning of olfactory receptors. Defining the boundaries of odor perception will enable design of experiments that representatively sample olfactory space and efficient search for novel odor compounds.

Relieve Nasal Obstruction Symptoms through Modulation of Airflow via a Novel Nasal Aid
Kanghyun Kim, Zhenxing Wu, Alexander A. Farag, Bradley A. Otto, Kai Zhao
The Ohio State University, Columbus, OH, USA

Nasal obstruction affects around 13% of the population, or 30 million people in US. However, the subjective complaints of obstruction correlates poorly with objective findings (e.g. nasal resistance), leading to poor treatment outcome. Here, we report that re-directing nasal airflow through a novel nasal plug with an embedded diagonal air channel can surprisingly relieve nasal obstruction symptoms despite further airflow constriction, on two groups of patients: empty nose syndrome (ENS n=30) and inferior turbinate hypertrophy + septal deviation (septal-turb n=40). ENS is characterized by a paradoxical sensation of nasal obstruction, despite a wide-open nasal airway, which may lead patients to severe anxiety and even suicidal attempts. In contrast, “septal-turb” fits the traditional diagnosis of nasal obstruction with CT evidence of a constricted airway. Patients were instructed to insert the plugs in their nostrils and rotated them to two standard directions (up and down - in counter-balanced order) and then a self-oriented most “comfortable” direction. The two distinct patient groups (one being nose “too-wide”, one being “too-narrow”) both reported significantly improved symptoms compared to the baseline, especially in the self-oriented direction (ENS6q 16.8+-5.0 to 8.6+-4.6, septal-turb VAS, 5.7+-2.1 to 3.6+-2.6, all p<0.05), suggesting that the improvement depends on personalized airflow stimulation of critical nasal mucosa regions. Individual CT based computational fluid models confirm nasal plug effectiveness in re-directing airflow to targeted nasal regions. This finding may drastically challenge traditional thinking of nasal obstruction as physical obstruction and may lead to novel therapeutic approaches based on optimal air/mucosa stimulation rather than on resistance.

Olfactory-trigeminal Masking Effects
Iryna Ruda¹, Franziska Sonja Müschenich³, Jessica Freiherr^1,2.
¹Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, ²Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany, ³Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

Within this research the masking behavior of a mixture consisting of eucalyptol and ammonia on a behavioral and neural level is explored. In Study 1 we established that eucalyptol has the potential to mask aversive odors, though, trigeminal enhancement can still be amplified and has to be prevented. In Study 2, we investigated the underlying neural network. A pleasant olfactory-trigeminal perception of the final product is an essential requirement for successful malodor coverage; however, half of the participants rated the mixture as pleasant while the other half rated it as unpleasant. These group differences were also demonstrated on the neural level. In the unpleasant group, activation in the anterior insula and SII was interpreted as evidence for an attentional shift towards the potentially threatening ammonia within the mixture and for trigeminal enhancement. The latter was observed on the behavioral level in the first study. In the pleasant group, no activation was statistically significant. Further, the piriform cortex, anterior midcingulate gyrus, inferior frontal gyrus, anterior insula were involved with regards to the all odors contrast and all participants. Observing the signal intensity in those areas, we discovered two peaks: an expected peak with a maximum at 8 seconds after stimulus onset and a second unexpected peak at 24-26 seconds after stimulus onset. Ongoing analyses hint towards a correlation of this later peak with perceptual ratings or a delayed trigeminal response. Our results highlight that a reliable olfactory and trigeminal masking of ammonia by means of eucalyptol was not possible. The complex mixture processing of olfactory-trigeminal stimuli, which could lead to a painful sensation, complicates the development of an efficient masking tool.

Interspecific Chemosensory Communication of Emotions: Reciprocal Recognition of Fear and Non-fear Body Odour Between Humans (Homo sapiens) and Horses (Equus ferus caballus)
Agnieszka Sabiniewicz^1,2, Piotr Sorokowski², Michał Białek², Karolina Tarnowska², Robert Świątek², Matthias Laska³.
¹Smell and Taste Clinic TU Dresden, Dresden, Germany, ²Institute of Psychology, University of Wrocław, Wrocław, Poland, ³Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden

Mammalian body odour conveys cues about an individual’s emotional state that can be recognised by conspecifics. So far, no studies have examined whether reciprocal recognition of emotions between humans and animals, based on body odour, occurs. Thus, the aim of the present study was to address this question in two experiments. In the first experiment, body odour samples were collected from 16 two years old thoroughbred horses (Equus ferus caballus) in a fear and a non-fear situation, respectively. The horse odour samples were then assessed by 73 human (Homo sapiens) odour raters. In the second experiment, body odour samples were collected from 10 adult humans in a fear and a happiness condition, respectively. The human body odour samples collected in these two conditions, together with a control condition, were then presented to a total of 21 horses. The results of the first experiment showed that humans, as a group, were able to correctly assign whether horse odour samples were collected under a fear or a non-fear condition, respectively. The results of the second experiment, in turn, demonstrated that the horses displayed some differential behaviour in response to human fear and happiness odour. The horses lifted their heads significantly more frequently and for longer in the fear and the control condition compared to the happiness condition. Similarly, the horses tended to touch a familiar person that was present during the test more frequently and for longer in the fear condition compared to the happiness condition. Additionally, depending on odour condition, the horses differed in the time they spent keeping their ears back. To conclude, the present study provides first evidence for reciprocal purely olfactory recognition of emotions between humans and horses.

Bitter taste receptors (TAS2Rs) mediate food allergy (FA):
Bitter Taste Hyper-Sensitivity to Quinine and Amarogentin Is Associated with Food Allergies
Zeping Shao¹, Yun Liu², Nadia de Jager³, Eugeni Roura¹.
¹Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Australia.²Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia.³Queensland Brain Institute, The University of Queensland, Brisbane, Australia

Food allergies have been defined as an immune response occurring soon after ingesting an otherwise innocuous, dietary protein. The activation of immune cells (i.e. T lymphocytes) occur after activation by specific peptides (referred to as epitopes) part of the amino acid sequence of the protein. Interestingly, several peptides have been identified as bitter receptor (TAS2R) agonists. For example, Gly-Phe-containing peptides have been identified as epitopes involved in peanut, tree nut, milk, and egg allergies among others. Interestingly, Gly-Phe is a high affinity ligand for TAS2R4. With the hypothesis that sensitivity to bitterants may be involved in food allergic responses, we performed sensory evaluations on 16 medically diagnosed food allergic (FA) and 16 non-food allergy (NFA) participants. Best estimate thresholds (BET) for quinine hydrochloride (quinine), amarogentin, thiamine hydrochloride (thiamine), 6-n-propylthiouracil (PROP) and caffeine were analyzed via discriminatory triangle test. The BET were significantly (P = 0.0226, one-way ANOVA) or tended to be (P = 0.0671) lower in FA group compared to NFA individuals for quinine and amarogentin, respectively. In contrast, no significant (P > 0.10) differences were observed related to the sensing of thiamine, PROP, or caffeine between the two groups. Quinine and amarogentin show high affinity to TAS2R4. Thus, it would appear that the bitter-hypersensitivity involving TAS2R4 observed in FA individuals may be related to a defensive response to avoid consumption of potential allergenic proteins. In conclusion, a significant hyper-sensitivity to bitter TAS2R4 ligands has been identified in FA compared to NFA volunteers. The potential role of TAS2R4 and other TAS2Rs in food allergies warrants further investigation.

The catnip/silver vine response in domestic cats: I, an identification of a potent bioactive compound from silver vine leaves
Reiko Uenoyama¹, Masaatsu Adachi^>2, Toshio Nishikawa², Masao Miyazaki¹.
¹Iwate University, Morioka, Japan, ²Nagoya University, Chikusa, Japan

Domestic cats exhibit a characteristic behavioral response on encounter with specific plants such as catnip (Nepeta cataria) and silver vine (Actinidia polygama). The response comprises chewing and licking the plants, face and head rubbing against the plants, and rolling over on the plants, whose biological significance had not been understood. This study aimed to establish a reliable and reproducible behavioral assay using a synthesized compound that could be controlled to elucidate the response in cats. Our studies started to purify bioactive compounds from silver vine leaves using liquid chromatography (LC) and cats. LC using a silica gel column gave two bioactive fractions; first fraction without iridoid compounds identified in previous studies carried out in 1950-1960 stimulated a more prolonged response than second fraction including them, suggesting that an important contribution of unidentified bioactive compounds in the first fraction. To identify unknown compounds, bioactive components were further purified by LC using C22 and C30 columns. GC/MS of the final bioactive fraction detected nepetalactol which had been missed in previous studies. Nepetalactol shares a similar structure with nepetalactone, a bioactive iridoid emitted from catnip, except for lactol and lactone moieties. In behavioral assays, not only domestic cats but also large felids, such as Amur leopards and Jaguars, exhibited face rubbing and rolling over in response to nepetalactol- impregnated filter paper. In conclusion, nepetalactol is the major component of silver vine to induce this potent response in Felidae species and useful to elucidate biological significances of this enigmatic response as a stimulant, as compared to plant materials that emit variable amounts of multiple volatile compounds.

Non-WEIRD Human Chemosensory Science
Maria G Veldhuizen¹ & Valentina Parma²
¹Department of Anatomy, Faculty of Medicine, Mersin University, Mersin, Turkey, ²Department of Psychology, Temple University, Philadelphia, PA, United States

Big scientific questions related to the chemical senses are being investigated by a community of chemosensory scientists in varying degrees of collaborations. Such problem-solving is unquestionably rooted in the culture of the societies those scientists live in. The chemical senses may be most acutely affected by culture, environment, social race and geography. As a result, most chemosensory knowledge is biased towards Western, educated, industrialized, rich and democratic (WEIRD) populations and research areas. It is a missed opportunity to not conduct more inclusive and collaborative research to solve complex chemosensory problems, as progress demands diverse perspectives and the accumulation of unbiased big data. In this symposium we propose themes in literature, methods and approaches that provide advancements in chemosensory science that can be widely and cross-culturally applicable. How can we use olfactory testing flexibly, for example for screening during a pandemic? How does culture shape odor awareness and, more in general our (chemo)sensory perception? How can we link basic scientific chemosensory discoveries to the lived experience of patients, in ways that make patients feel heard and reinforces confidence in science?

Structural Remodeling of Peripheral Taste Neurons
Zachary D. Whiddon, Jaleia B. Marshall, Aaron W. McGee, Robin F. Krimm.
University of Louisville School of Medicine, Louisville, KY, United States

Taste neurons receive information from taste-transducing cells that undergo continual turnover. Given that taste neurons must connect with new cells, we asked if they undergo structural remodeling over time using intravital imaging. Because the half-life of taste-transducing cells is 10 days, we speculated that half of the arbors (portion of the peripheral taste axon that innervates the taste bud) would remodel within 10 days in order to form connections with new cells. So, we sampled arbor structure every 12 hours for 10 days. Since synapses occur on distal (terminal) branches of the arbor, we quantified the change in the number of terminal branches over time. We found that all arbors altered their complexity by adding or pruning terminal branches within the first 5 days, and 19 of 31 arbors changed terminal branch number in the first 24 hours. On average 1 terminal branch was gained or lost every 16.0 hours. Given this surprising speed, we imaged arbors at 4 hours for 12 hours. We found that 42.4% of arbors gained or lost a terminal branch more than once in a 12-hour period. and that a terminal branch was gained or lost once every 6.8 hours. This finding indicates terminal branches remodel much faster than would be predicted by taste bud cell turnover. To investigate if terminal arbor size is altered over time, we measured the volume the arbor occupies within the taste bud (convex hull). Minimum hull volume predicts maximum hull volume (R2=0.937), indicating that arbor size does not change over the full dynamic range in 10 days. Lastly, we examined 18 arbors in 36 taste buds every 10 days for 50 days and no arbors were gained or lost. Together these data demonstrate that terminal arbor number is stable, but arbor structure is plastic, with terminal branches undergoing rapid continuous remodeling.

Max Mozell: The Work Lives On
Theresa White^1,2
¹Le Moyne College, Syracuse, NY, United States, ²Upstate Medical University, Syracuse, NY, United States

Max Mozell, one of AChemS’ founders, passed away in March of 2020. Max's life in research was dominated by the study of olfactory perception and the effects of its loss on the patients with olfactory loss that he saw at the Smell and Taste Disorders Clinic at SUNY Upstate Medical University in Syracuse. This symposium is meant to honor his contributions to chemosensory research by looking at the latest developments in our understanding of the events in the nasal cavity. One of the things that Max would often say is that although many mysteries remain in understanding olfactory perception, at least one aspect is clear: if molecules from odorous substances can’t reach the olfactory receptors, there can be no perception. The airflow to deliver the molecules and the way that the molecules interact with the nasal mucosa are therefore central to the olfactory perceptual process. Changes in either the number of molecules or their distribution (and sorption) on the mucosa then alters incoming olfactory information, possibly resulting in dysosmia. This symposium will focus on recent findings in the peripheral olfactory system involving sniffing behavior, odor sorption, and molecular biology, as well as their application to clinical chemosensory disorders.

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