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The dichotomy between certainty of results and resources is exemplified in sensory affective testing. Furthermore, the data produced through using 9-point hedonic scales has a unique underlying distribution that is dependent on consumer scale usage and the product itself. We use a combination of resampling real sensory hedonic data with simulations to characterize how the outcome of affective sensory tests change across a range of participants and product space. We found that most data is multimodal and non-parametric in nature, putting in question conventional measures of statistical power and sample size assessments that are parametric. Through a novel method of pseudo-simulation that uses the actual underlying distribution, we were able to find sample sizes and statistical power across a wide range of sample sizes. To our surprise, contrasting this new method to conventional methods of sample size estimation, gaussian sample size estimates consistently give a similar number of participants needed for a particular statistical power. Our novel method also compared similarly to sample size estimates generated from nonparametric methods. Our findings highlight the unique underlying distributions of data collected from 9-point hedonic scales and show how that distribution does not thwart conventional methods of sample size estimation.

Background: The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O). Methods: Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus. Results: The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies. Conclusion: This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Neurotypical individuals have subjective sensitivity differences that may overlap with more heavily studied clinical populations. However, it is not known whether these subjective differences in sensory sensitivity are modality specific, or lead to behavioral shifts. In our experiment, we measured the oral touch sensitivity and food texture awareness differences in two neurotypical groups having either a high or low subjective sensitivity in touch modality. To measure oral touch sensitivity, individuals performed discrimination tasks across three types of stimuli (liquid, semisolid, and solid). Next, they performed two sorting exercises for two texture-centric food products: cookies and crackers. The stimuli that required low oral processing (liquid) were discriminated at higher rates by participants with high subjective sensitivity. Additionally, discrimination strategies between several foods in the same product space were different across the groups, and each group used attributes other than food texture as differentiating characteristics. The results show subjective touch sensitivity influences behavior (sensitivity and awareness). However, we show that the relationship between subjective touch sensitivity and behavior generalizes beyond just touch to other sensory modalities.

Advances in theoretical understanding are frequently unlocked by access to large, diverse experimental datasets. Olfactory neuroscience and psychophysics remain years behind the other senses in part because rich datasets linking olfactory stimuli with their corresponding percepts, behaviors, and neural pathways underlying this transformation, remain scarce. Here we present a concerted effort to unlock and unify dozens of stimulus-linked olfactory datasets across species and modalities under a unified framework called Pyrfume. We present examples of how researchers might use Pyrfume to conduct novel analyses uncovering new principles, introduce trainees to the field, or construct benchmarks for machine olfaction.

Height preferences reflecting positive assortative mating for height—wherein an individual’s own height positively predicts the preferred height of their mate—have been observed in several distinct human populations and are thought to increase reproductive fitness. However, the extent to which assortative preferences for height differ strategically for short-term versus long-term relationship partners, as they do for numerous other indices of mate quality, remains unclear. We explore this possibility in a large representative sample of over 500 men and women aged 15–77 from Canada, Cuba, Norway and the United States. Participants’ own heights were measured, and they indicated their height preferences for a long-term and short-term mate using graphic stimuli containing metric indices. Replicating the “male-taller norm,” participants on average preferred taller-than-average male mates, and shorter-than-average female mates. Positive assortative preferences for height were observed across sexes and samples, however the strength of these height preferences varied with relationship context for men, and not for women. Taller men preferred relatively shorter women for short-term relationships than for long-term relationships, indicating stronger assortative preferences for height in a long-term context. These results provide preliminary evidence that, in addition to mate preferences for other physical traits related to mate quality such as masculinity in the body, face, and voice, assortative preferences for height do vary as a function of expected relationship length, but this was surprisingly only observed in preferences for female height.

Purpose The present study aimed to establish a test battery for the clinical assessment of retronasal odor thresholds and retronasal odor identification. Study design Prospective case–control series. Methods Sixty participants (36 women, 24 men, mean age 37.6 ± 19.4 years) were enrolled in this study; 36 were healthy controls and 24 were patients with olfactory dysfunction. Orthonasal olfactory function was assessed with the “Sniffin’ Sticks” test battery. Retronasal olfaction was assessed with oral odorant delivery using special containers for threshold function, and with oral tasteless powders for odor identification. Results Retronasal and orthonasal olfaction were significantly correlated for threshold scores, identification score, and the sum of threshold and identification score (TI score). Validity analyses showed that the retronasal TI score was able to discriminate between healthy controls and patients with olfactory dysfunction. Conclusions Normosmic participants can be distinctly differentiated from patients with olfactory dysfunction using a valid test battery comprised of retronasal threshold and identification tests. Based on the current findings, we advocate a TI score of 16 as a cut-off between patients and controls. Therefore, TI scores of 17 and above would indicate retronasal normosmia.

The COVID-19 pandemic has increased the prevalence of people suffering from olfactory disorders. In the absence of quick, population-wide olfactory tests, we developed SCENTinel, a rapid, inexpensive smell test to assess odor detection, intensity, and identification ability, which can discriminate anosmia (e.g., total smell loss) from normosmia (e.g., normal sense of smell) using a single odor. A new version, SCENTinel 1.1, extends the original test with one of four possible odors and a hedonic subtest (“how pleasant is the odor”). The purpose of this study was to determine if SCENTinel 1.1 can discriminate other types of olfactory disorders common to COVID-19, such as hyposmia (e.g., reduced sense of smell), parosmia (e.g., distorted odor perception), and phantosmia (e.g., odor sensation without an odor source). Participants (N=381) were divided into three groups based on their self-reported olfactory function: quantitative smell disorder (anosmia or hyposmia, N=135), qualitative smell disorder (parosmia and/or phantosmia; n=86), and normosmia (N=66). SCENTinel 1.1 classifies anosmia and normosmia groups with high sensitivity (AUC=0.94), similar to SCENTinel 1.0 (AUC=0.95). SCENTinel 1.1 also accurately discriminates quantitative from qualitative (AUC=0.76), and normosmia (AUC=0.84), and normosmia from qualitative (AUC=0.73) groups. We also considered a subset of participants who only reported one type of olfactory disorder. SCENTinel 1.1 discriminates hyposmia from parosmia (AUC=0.89), and anosmia (AUC=0.78); as well as parosmia from anosmia (AUC=0.82). Participants with parosmia had a significantly lower hedonic score than those without parosmia, indicating odor distortions are unpleasant. SCENTinel 1.1 is a rapid smell test that can discriminate quantitative (anosmia, hyposmia) and qualitative (parosmia, phantosmia) olfactory disorders, and it is among the only direct tests to rapidly screen for parosmia.

It is estimated that 20%–67% of those with COVID-19 develop olfactory disorders, depending on the SARS-CoV-2 variant. However, there is an absence of quick, population-wide olfactory tests to screen for olfactory disorders. The purpose of this study was to provide a proof-of-concept that SCENTinel 1.1, a rapid, inexpensive, population-wide olfactory test, can discriminate between anosmia (total smell loss), hyposmia (reduced sense of smell), parosmia (distorted odor perception), and phantosmia (odor sensation without a source). Participants were mailed a SCENTinel 1.1 test, which measures odor detection, intensity, identification, and pleasantness, using one of 4 possible odors. Those who completed the test (N = 287) were divided into groups based on their self-reported olfactory function: quantitative olfactory disorder only (anosmia or hyposmia, N = 135), qualitative olfactory disorder only (parosmia and/or phantosmia; N = 86), and normosmia (normal sense of smell; N = 66). SCENTinel 1.1 accurately discriminates quantitative olfactory disorders, qualitative olfactory disorders, and normosmia groups. When olfactory disorders were assessed individually, SCENTinel 1.1 discriminates between hyposmia, parosmia, and anosmia. Participants with parosmia rated common odors less pleasant than those without parosmia. We provide proof-of-concept that SCENTinel 1.1, a rapid smell test, can discriminate quantitative and qualitative olfactory disorders, and is the only direct test to rapidly discriminate parosmia.

Variability in human olfactory sensitivity has been attributed to individual-level factors such as genetics, age, sex, medical history of infections and trauma, neurogenerative diseases, and emotional disorders. Scarce evidence exists on the cross-cultural variation in olfactory sensitivity. Hence, we performed 2 studies to estimate the variability in olfactory threshold as a function of location and environment. Study 1 involved 11 laboratories from 4 continents (N = 802). In each location, in a designated laboratory, approximately 80 subjects underwent olfactory sensitivity testing with custom-made tests with eucalyptol and phenylethanol (PEA) odors. Tests were based on the Threshold subtest of the Sniffin' Sticks battery. In Study 2, we compared olfactory sensitivity and suprathreshold perception of PEA and eucalyptol in 2 Chinese (N = 160) and 2 Indian (N = 92) populations-one based in their native country and the other in Germany. Both studies present large-scale evidence that olfactory sensitivity varies as a function of geographical location and suggest that environmental factors play an important role in shaping olfactory sensitivity and suprathreshold olfactory perception. We delineate further steps necessary to identify specific factors underlying uncovered variability and the relationship between olfactory sensitivity and suprathreshold odor perception. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Texture is a prominent feature in foods and consequently can be the reason a food is accepted or rejected. However, other sensory attributes, such as flavor/taste, aroma, sound, and appearance may also lead to the rejection of food and motivations other than unpleasantness exist in unacceptance. To date, these motivations for food rejection have been studied in isolation and their relationships with psychological factors have not been tested. This study measured reasons people reject a food and probed into the specifics of texture rejection. A large U.S. sample (N = 473) was asked to rate their motivations for rejecting a food, list foods that were disliked due to unpleasant sensory attributes, specify the unpleasant sensory attribute(s), and complete an assessment of general touch sensitivity. Results showed 94% of individuals reject a food due to its texture, a rate comparable to flavor-based rejection. Looking at the number of foods being rejected, flavor was the most common food attribute, followed by texture and then aroma. From a linguistic standpoint, aversive textures encompass a large vocabulary, larger than liked textures, and the same food may be rejected due to a single or combination of texture terms. Viscosity (e.g., slimy) and hardness (e.g., mushy) are the most common aversive texture types, but through cluster analysis subsets of individuals were identified that are more aversive to other textures. This study emphasizes the role of aversive textures in food rejection and provides many avenues for future investigations.

Among those many individuals who experience a reduced odor sensitivity (hyposmia/anosmia), some individuals also have disorders that lead to odor distortion, such as parosmia (i.e. distorted odor with a known source), or odor phantoms (i.e. odor sensation without an odor source). We surveyed a large population with at least one olfactory disorder (N = 2031) and found that odor distortions were common (46%), with respondents reporting either parosmia (19%), phantosmia (11%), or both (16%). In comparison to respondents with hyposmia or anosmia, respondents with parosmia were more likely to be female, young, and suffering from post-viral olfactory loss (P < 0.001), while respondents with phantosmia were more likely to be middle-aged (P < 0.01) and experiencing symptoms caused by head trauma (P < 0.01). In addition, parosmia, compared to phantosmia or anosmia/hyposmia, was most prevalent 3 months to a year after olfactory symptom onset (P < 0.001), which coincides with the timeline of physiological recovery. Finally, we observed that the frequency and duration of distortions negatively affects the quality of life, with parosmia showing a higher range of severity than phantosmia (P < 0.001). Previous research often grouped these distortions together, but our results show that they have distinct patterns of demographics, medical history, and loss in quality of life.

ImportanceSudden smell loss is a specific early symptom of COVID-19, with an estimated prevalence of ~40% to 75%. Smell impairment affects physical and mental health, and dietary behavior. Thus, it is critical to understand the rate and time course of smell recovery.ObjectiveTo characterize smell function and recovery up to 11 months post COVID-19 infection.Settings, ParticipantsThis longitudinal survey of individuals suffering COVID-19-related smell loss assessed disease symptoms and gustatory and olfactory function. Participants (n=12,313) who completed an initial respiratory symptoms, chemosensory function and COVID-19 diagnosis survey (S1) between April and September 2020 and completed a follow-up survey (S2) between September 2020 and February 2021; 27.5% participants responded (n=3,386), with 1,468 being diagnosed with COVID-19 and suffering co-occurring smell and taste loss at the beginning of their illness.Main Outcomes & MeasuresPrimary outcomes are ratings of smell and taste function on a visual analog scale, and self-report of parosmia (smell distortions) and phantosmia (unexplained smells). Secondary outcomes include a checklist of other COVID-19 symptoms.ResultsOn follow-up (median time since COVID-19 onset ~200 days), ~60% of women and ~48% of men reported less than 80% of their pre-illness smell ability. Taste typically recovered faster than smell, and taste loss rarely persisted if smell recovered. Prevalence of parosmia and phantosmia was ~10% of participants in S1 and increased substantially in S2: ~47% for parosmia and ~25% for phantosmia. Persistent smell impairment was associated with more symptoms overall, suggesting it may be a key marker of long-COVID. During COVID-19 illness, the ability to smell was slightly lower among those who did not recover their pre-illness ability to smell at S2.Conclusions and RelevanceWhile smell loss improves for many individuals who lost it due to COVID-19, the prevalence of parosmia and phantosmia increases substantially over time. Olfactory dysfunction is also associated with wider COVID-19 symptoms and may persist for many months after COVID-19 onset. Taste loss in the absence of smell loss is rare. Persistent qualitative smell symptoms are emerging as common long term sequelae; more research into treatment options is strongly warranted given that conservative estimates suggest millions of individuals may experience parosmia following COVID-19. Healthcare providers worldwide need to be prepared to treat post COVID-19 secondary effects on physical and mental health.Trial registrationThis project was pre-registered at OSF: https://osf.io/3e6zc.Graphical abstractKey PointsQuestionWhat are the characteristics of smell and taste recovery of COVID-19 patients?FindingsIn this preregistered observational study of 1,468 participants, smell loss is associated with a higher number of COVID-19 symptoms, and may persist for at least 11 months following disease onset. While a majority of participants report quantitative improvement in their ability to smell, the prevalence of parosmia and phantosmia increases substantially at follow-up. Taste recovers faster than smell, suggesting taste and smell recover separately and can be distinguished by the respondents.MeaningOlfactory dysfunction appears to be a component of long-COVID, with parosmia as a prominent symptom in almost half of those with smell loss. More research into treatment is needed, especially given that olfactory dysfunction is associated with depression and loss of appetite. Health professionals should be aware of these common and long lasting effects.

Among those many individuals who suffer from a reduced odor sensitivity (hyposmia/anosmia) some individuals also experience disorders that lead to odor distortion, such as parosmia (i.e., distorted odor with a known source), or odor phantoms (i.e., odor sensation without an odor source). We surveyed a large population with at least one olfactory disorder (N = 2031) and found that odor distortions were common (46%), with respondents reporting either parosmia (19%), phantosmia (11%), or both (16%). In comparison to respondents with hyposmia or anosmia, respondents with parosmia were more likely to be female, young, and suffered from post-viral olfactory loss (p < 0.001), while phantosmia occurred most frequently in middle-aged respondents (p < 0.01) and was more likely to be caused by head trauma than parosmia (p < 0.01). A higher prevalence of odor distortion was observed 3 months to a year after their olfactory symptom onset (p < 0.001), which coincides with the timeline of physiological recovery. Additionally, we observed that the frequency and duration of distortions negatively affects quality of life, with parosmia showing a higher range of severity than phantosmia (p < 0.001). Previous research often grouped these distortions together, but our results show that they have distinct patterns of demographics, medical history, and loss in quality of life.

Chemesthesis, along with taste and olfaction, is a primary component of flavor that engages the trigeminal system through specific chemical binding. For instance, many gums or confectionaries incorporate chemical cooling agents, such as Wilkinson Sword (WS) compounds, to create the sensation of coldness. The current study was designed to evaluate crossmodal associations of color and aroma with the chemesthetic perception of cooling. A “minty” and non-odorized set of confectionary stimuli, colored green, blue or white, with moderate cooling properties (with WS-3) were used in this study. In the first session, participants were randomly presented a stimulus and asked to rate several attributes including its cooling intensity on a generalized Labeled Magnitude Scale (gLMS). In the second session, the same participants were asked to relate cooling levels to different colors and which color relates to the “minty” odor. Additionally, open-ended reasons were given for association choices. Appearance and odor influenced the intensity of cooling sensation. In particular, the odorized and blue samples were rated as cooler than the non-odorized and other colored samples, respectively. The follow-up session confirms blue as a color associated with cooling properties, especially cool objects/abstract concepts. Meanwhile, odor’s enhancement on cooling sensation may be more perceptual in nature through affective matching from enhanced flavor.

Objective/hypothesis A common, lasting condition from traumatic brain injury is impairment to smell. In patients with olfactory impairment, recent meta-analyses have demonstrated that olfactory training consistently improves higher-order functions, such as odor identification. The focus of this work was to assess effects of olfactory training (OT) in posttraumatic olfactory loss patients through several metrics including psychophysical, olfactory bulb (OB) volume, and functional magnetic resonance imaging. Study design Prospective cohort study. Methods Sniffin' Sticks were used to classify two patient groups (anosmic [N = 23] and hyposmic [N = 14]) and measure changes after OT. Additionally patients were asked the intensity, valence, and uncued identification of odors presented (coffee and peach) within the magnetic resonance imaging scanner before and after olfactory training. Olfactory training was performed twice daily with a four-odor training set for 24 weeks, and sets were replaced halfway through the entire training session (~12 weeks). Results Patients had an increase in test scores (threshold and identification) and in-scanner intensity ratings and identification. Anosmic patients showed improved olfactory thresholds to 2-phenylethanol, increased intensity ratings, and activation in the right superior frontal gyrus (SFG) to odors after OT. Hyposmic patients were able to identify odors better after training. This behavior was mirrored with increased, ipsilateral activations in semantic processing areas such as Broca's area, left angular gyrus, and left SFG. Conclusions Taken together, along with neither patient group showing changes in OB volumes, OT improves olfactory performance in patients with posttraumatic olfactory loss and seems to be driven, at least in part, by top-down processes (central) rather than bottom-up (peripheral). Levels of evidence 2 Laryngoscope, 129:1737-1743, 2019.

As individuals explore their environment, they experience smells and recall memories associated with them. This close relationship between smell and memory has been extensively studied; however, less attention has been paid to the direct comparison of associative and non‐associative memory odours. This study aimed to measure responses to odours related to memories and responses to odours related to none or few memories using electroencephalography. In a within‐subject design, 25 individuals received two food odours (chocolate and apple strudel) while olfactory event‐related potentials (oERP) were recorded. These stimuli were chosen because individuals had an autobiographical memory associated with either one of the odours. Additionally, individuals rated the characteristics of the odours and were tested on their memory capacity. The results indicate that apple strudel, but not chocolate, produced larger oERP amplitudes when associated with a memory. Additionally, the apple strudel odour was found to be less pleasant and familiar than the chocolate odour, and fewer individuals had an association with the apple strudel odour. This indicates that oERP can be used to indicate the strength of odour‐related memories.

Olfactory research in humans has largely focused on odors perceived via sniffing, orthonasal olfaction, whereas odors perceived from the mouth, retronasal olfaction, are less well understood. Prior work on retronasally presented odors involves animal models and focus mainly on odor sensitivity, but little is known about retronasal olfactory perception and cognition in humans. In this study, we compared orthonasal and retronasal odor presentation routes to investigate differences in odor descriptions and evaluations. Thirty-six individuals participated in a within-subjects study using twelve odors (varying in pleasantness and edibility) in perceptual and semantic tasks. Orthonasal presentation was associated with a better ability to identify odors, and with more concrete (and source-based) language. Exploratory analyses revealed that whereas orthonasal odors were described with words that had visual associations, retronasal odors were described with words that had interoceptive associations. Interestingly, these route-dependent differences in descriptor usage were not explained by differences in sensitivity and intensity, suggesting instead a cognitive and linguistic processing difference between odors presented orthonasally and retronasally. Our results indicate that olfaction is, in fact, a dual sense, in which the routes change the perception of an odor.

We present a rare case in which a patient has gained her smell after lifelong anosmia. The patient was objectively tested and diagnosed with functional anosmia at age 13 and reported they were experiencing a new sensation of smell at age 22. Our results show an electrophysiological signal for two unimodal odorants. The patient had a retronasal score in the hyposmic range and self-reported the ability to smell non-trigeminal odors, but reported being disturbed by the presence of the new sense and co-occurrence of phantosmia. We discuss our case in routes of neurogenesis and non-forming memory association with odors.

Olfactory impairment after a traumatic impact to the head is associated with changes in olfactory cortex, including decreased gray matter density and decreased BOLD response to odors. Much less is known about the role of other cortical areas in olfactory impairment. We used fMRI in a sample of 63 participants, consisting of 25 with post-traumatic functional anosmia, 16 with post-traumatic hyposmia, and 22 healthy controls with normosmia to investigate whole brain response to odors. Similar neural responses were observed across the groups to odor versus odorless stimuli in the primary olfactory areas in piriform cortex, whereas response in the frontal operculum and anterior insula (fO/aI) increased with olfactory function (normosmia > hyposmia > functional anosmia). Unexpectedly, a negative association was observed between response and olfactory perceptual function in the mediodorsal thalamus (mdT), ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (pCC). Finally, connectivity within a network consisting of vmPFC, fO, and pCC could be used to successfully classify participants as having functional anosmia or normosmia. We conclude that, at the neural level, olfactory impairment due to head trauma is best characterized by heightened responses and differential connectivity in higher-order areas beyond olfactory cortex.

Neurotypical individuals have subjective sensitivity differences that may overlap with the more heavily studied clinical populations. However, it is not known whether these subjective differences in sensory sensitivity are modality specific or lead to behavioral shifts. In our experiment, we measured the touch sensitivity and texture awareness differences in two neurotypical groups having either a high or low subjective sensitivity in touch modality. To measure touch sensitivity, individuals performed discrimination tasks across three types of stimuli (liquid, semi-solid, and solid). Next, they performed two sorting exercises for two texture-centric food products: cookies and crackers. The stimuli that required low oral processing (liquid) were discriminated at higher rates by the high subjective sensitivity compared to the solid stimuli. Additionally, discrimination strategies between several foods in the same product space were different across the groups, and each group used attributes other than texture as differentiating characteristics. The results show subjective touch sensitivity influences behavior (sensitivity and awareness). However, we show that the relationship between subjective touch sensitivity and behavior generalizes across several modalities.

BackgroundCommercially available smell tests are primarily used in research or in-depth clinical evaluations, but are too costly and lengthy for population surveillance in health emergencies like COVID-19. We developed the SCENTinel 1.0 test which rapidly evaluates three olfactory functions (detection, intensity, and identification). We tested whether self-administering the SCENTinel 1.0 test discriminates between individuals with smell loss or average smell ability (normosmics), and provides comparable performance as the validated and standardized NIH Toolbox® Odor Identification Test in normosmics.MethodsUsing Bayesian linear models and prognostic classification algorithms, we compared the SCENTinel 1.0 performance of a group of self-reported anosmics (N=111, 47±13yo, F=71%,) and normosmics (N=154, 47±14yo, F=74%), as well as individuals reporting other smell disorders (e.g., hyposmia, parosmia; N=42, 55±10yo, F=67%).ResultsNinety-four percent of normosmics met our SCENTinel 1.0 accuracy criteria, while only 10% of anosmics and 64% of individuals with other smell disorders did. Overall performance on SCENTinel 1.0 predicted belonging to the normosmic group better than identification or detection alone (vs. anosmic: AUC=0.95, Sensitivity=0.72, Specificity=0.94). Odor intensity provided the best single-feature predictor to classify normosmics. Among normosmics, 92% met the accuracy criteria at both SCENTinel 1.0 and the NIH Toolbox® Odor Identification Test.ConclusionsSCENTinel 1.0 is a practical test able to discriminate individuals with smell loss and is likely to be useful in many clinical situations, including COVID-19 symptom screening.

Olfactory research in humans has largely focused on odors perceived via sniffing, orthonasal olfaction, while ignoring odors perceived from the mouth, retronasal olfaction. Prior work on retronasally presented odors use animal models and focus mainly on odor sensitivity, but little is known about retronasal olfactory perception and cognition in humans. In this study, we compared orthonasal and retronasal odor presentation routes to investigate differences in odor descriptions and evaluations. Thirty-six individuals participated in a within-subjects study using twelve odors (varying in pleasantness and edibility) in perceptual and semantic tasks. As expected, we found route-dependent differences in perceptual odor quality (pleasantness, edibility, and familiarity ratings), and a better ability to identify odors during orthonasal presentation. Additionally, more concrete (and source-based) language was used when describing odors presented orthonasally. Exploratory analyses revealed that while orthonasal odors were described with words that had visual associations, retronasal odors were described with words that had interoceptive associations. Interestingly, these route-dependent differences in descriptor usage were not explained by sensitivity and intensity differences, suggesting cognitive and linguistic processes differed between odors presented orthonasally and retronasally. Our results indicate that olfaction is in fact a dual sense, in which the routes change the perception of an odor.

The main neurological manifestation of COVID-19 is loss of smell or taste. The high incidence of smell loss without significant rhinorrhea or nasal congestion suggests that SARS-CoV-2 targets the chemical senses through mechanisms distinct from those used by endemic coronaviruses or other common cold-causing agents. Here we review recently developed hypotheses about how SARS-CoV-2 might alter the cells and circuits involved in chemosensory processing and thereby change perception. Given our limited understanding of SARS-CoV-2 pathogenesis, we propose future experiments to elucidate disease mechanisms and highlight the relevance of this ongoing work to understanding how the virus might alter brain function more broadly., Impairments of smell and taste perception are two of the main symptoms of COVID–19. In this issue of Neuron, Cooper et al. focus on these chemosensory symptoms and review recent hypotheses of the putative mechanisms mediating the loss of taste and smell through COVID–19.

Olfactory impairment after trauma is associated with changes in olfactory cortex, including decreased gray matter density and decreased response to odors. Much less is known about the role of other cortical areas in olfactory impairment. We used fMRI in a sample of 63 participants, consisting of 25 with post-traumatic functional anosmia, 16 with post-traumatic hyposmia, and 22 healthy controls with normosmia to investigate whole brain response to odors. Similar neural responses were observed across the groups to odor versus odorless stimuli in the primary olfactory areas in piriform cortex, whereas response in the frontal operculum and anterior insula (fO/al) increased with olfactory function (normosmia > hyposmia > functional anosmia). Unexpectedly, a negative association was observed between response and olfactory function in the mediodorsal thalamus (mdT), ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (pCC). Finally, connectivity within a network consisting of vmPFC, fO, and pCC could be used to successfully classify participants as having functional anosmia or normosmia. We conclude that, at the neural level, olfactory impairment due to head trauma is best characterized by heightened responses and differential connectivity in higher-order areas beyond olfactory cortex.Significance StatementOlfactory impairment affects a quarter of the population, with subjective complaints usually confirmed with psychophysical measurements. Here, we demonstrate that the degree of olfactory impairment can also be categorized using neural responses to odors. Remarkably, regions with neural responses that were predictive usually showed an increase in response to odors with degree of impairment, rather than a reduction, as might be expected. Further, predictive cortical regions were not isolated to canonical olfactory areas.

A wealth of rapidly evolving reports suggests that olfaction and taste disturbances may be manifestations of the novel COVID-19 pandemic. While otolaryngological societies worldwide have started to consider chemosensory evaluation as a screening tool for COVID-19 infection, the true nature of the relationship between the changes in chemosensory ability and COVID-19 is unclear. Our goal with this review is to provide a brief overview of published and archived literature, as well as the anecdotal reports and social trends related to this topic up to April 29, 2020. We also aim to draw parallels between the clinical/chemosensory symptomology reported in association to past coronavirus pandemics (such as SARS and MERS) and the novel COVID-19. This review also highlights current evidence on persistent chemosensory disturbances after the infection has resolved. Overall, our analysis pinpoints the need for further studies: (1) to better quantify olfaction and taste disturbances associated with SARS-CoV-2 infection, compared to those of other viral and respiratory infections, (2) to understand the relation between smell, taste, and chemesthesis disturbances in COVID-19, and (3) to understand how persistent are these disturbances after the infection has resolved.

Cross-modal reorganization takes place for sensory cortices when there is no more primary input. For instance, the visual cortex in blind individuals which receives no visual input starts responding to auditory and tactile stimuli. Reorganization may improve or degrade processing of other modality inputs, via bottom-up compensational processes and top-down updating. In two experiments, we measured the spatial tactile response in a large sample of early- (N = 49) and late-blind (N = 51) individuals with varying levels of Braille proficiencies, and early-deaf (N = 69) with varying levels of hearing devices against separate hearing and sighted controls. Spatial tactile responses were measured using a standard gradient orientation task on two locations, the finger and tongue. Experiments show limited to no advantage in passive tactile response for blind individuals and degradation for deaf individuals at the finger. However, the use of hearing devices decreased the tactile impairment in early-deaf individuals. Also, no differences in age-related decline in both sensory-impaired groups were shown. Results show less tactile acuity differences between blind and sighted than previously reported, but supports recent reports of tactile impairment among the early-deaf.

Objective/Hypothesis: Taste disturbances are often seen in patients after middle ear surgery due to the stress received by an unprotected chorda tympani. It has also been reported that loss in tactile sensitivity may accompany this issue. The current study was designed to measure electrical, chemical, and tactile sensitives of several senses involved in oral processing, smell, taste and touch, over time. Study Design: Prospective cohort study. Methods: For three time points, one before middle ear surgery and two after operation (about 5 and 23 days), sensitivity thresholds were obtained using electrogustometry (electrical taste), taste strips (chemical taste), Sniffin’ Sticks (smell) and Von Frey Hairs (point-pressure tactile sensitivity). Results: The results show a decline in both chemical and electrical taste responses. Additionally, the electrical taste response showed more sensitivity to deviations and no sign of recovery unlike the chemical taste response. Mechanosensory function of the anterior tongue and olfactory function was not strongly affected by middle ear surgery. Conclusion: Taste responses, but not mechanosensory or olfaction function, are altered after middle ear surgery. Due to the effects that taste loss has on quality of life, gustometry is recommended for this group of patients. Levels of Evidence: 4

Olfactory habituation results from prolonged exposure to an odor, leading to perceptual changes defined by several characteristics. To date, human habituation research has focused on orthonasal olfaction which is perceived externally while ignoring internal routes of odor perception related to flavor. In our study, we conducted two experiments to characterize retronasal olfactory habituation and measured its impact on flavor perception. In Experiment 1, participants were presented a food odor and non-food odor retronasally, using an orally adhered strip. Each participant rated the odor intensity using a time-intensity procedure. After exposure, the participants ate a lime-flavored gummy and rated the lime flavor. In experiment 2, the same procedure was performed for a low-level lime odor, a simple (lime oil) and complex (lime oil + sucrose + citric acid) beverage as the flavor stimuli. Our results demonstrated two known principles of habituation for retronasally presented odors: (1) prolonged exposure leads to decreased perception and (2) weaker stimuli lead to more rapid habituation. Additionally, we found that the non-food odor habituated slower than the food odor; however, the participants seemed to recover simultaneously upon food and beverage consumption leading to no change in flavor perception. The findings of this study give evidence that we habituate to different odors at different rates; more specifically, we provide evidence that differentiates between odor origin and concentration. This is the first time-intensity characterization of retronasal odor habituation. Additionally, a novel method of administering retronasal odors is presented.

The preference of sweetened foods can be influenced by a variety of biological, psychological, sociological, and environmental factors. In this study, we focused on differences across three distinct societies: 1) a modern society (i.e., Polish people, n = 199), 2) forager-horticulturalists from Amazon/Bolivia (Tsimane', n = 138), and 3) traditional hunter-gatherers from Tanzania (Hadza, n = 81). To measure sweet preference, participants were asked to drink three cups containing slightly acidic solutions (pH = 2.79) varying in sucrose concentration (w/v; 0%, 25%, 67%). Only 5% of the Polish participants chose the sweetest cup as their favorite, while this cup was chosen by 74% of the Hadza and 53% of the Tsimane’ participants. Further, age was an inversely related to sweet preference for Polish participants; however, age did not predict preferences for both Tsimane’ and Hadza tribes. We discuss our findings in the context of environmental and cultural differences between the participating populations.

Odors are typically bimodal in nature, interacting with the olfactory and trigeminal systems. The trigeminal component may be noticed (e.g. menthol) or perceptually ignored, leading to different neural substrates being recruited during odor encoding. Therefore, the current study was designed to explore the perceptual and central-nervous activations in response to pleasant bimodal odors using functional magnetic resonance imaging (fMRI). In this study, healthy subjects were exposed to odorants alone (unimodal) or with a "cooling" trigeminal component (bimodal) at sub- and suprathreshold concentrations with a portable olfactometer in a 3T fMRI scanner. Within the scanner, subjects reported all odorants as pleasant and intensity increasing with trigeminal concentration. Many of the regions of interest [orbital frontal cortex (OFC), insula, thalamus, cerebellum, postcentral gyrus and cingulate cortex] were activated during bimodal odor conditions when contrasted with unimodal, and interestingly, most of these activations were seen prior to trigeminal perception (e.g. at a sub-threshold level). This includes large bilateral activations within the OFC, insula, cerebellum and parts of the cingulate cortex. Additionally, activation of the thalamus was seen early in the stages of bimodal odor encoding suggesting its role of mediating attention toward the presence of two stimuli. Lastly, intensity encoding during bimodal processing shows overlap of previously demonstrated simple trigeminal encoding areas (medial cingulate cortex) and the more complex olfactory encoding areas (bilateral insula, superior temporal gyrus, OFC, and cerebellum), but not the amygdala.

Objectives/Hypothesis Olfactory dysfunction is common among the general population, with chronic rhinosinusitis (CRS) as one of the leading causes. Patients affected by CRS often report changes in taste sensations; however, quantitative measurements have not been performed to date. Therefore, the present study aimed to investigate gustatory and olfactory function in CRS patients prior to and after multimodal treatment. Study Design Prospective cohort study. Methods Twenty-one patients suffering from CRS with nasal polyps (14 male, seven female) with a mean age of 48 ± 15 years were included in the study. Chemosensory function was assessed prior to and approximately 190 days after multimodal treatment, which included endoscopic sinus surgery, oral antibiotics for 5 days, oral steroids for 12 days, and at least 6 weeks of topical nasal steroids. Olfactory function was tested with the Sniffin' Sticks test battery, whereas gustatory function was measured with taste strips. A clinically relevant change in olfactory function was defined as a change of ≥5 points in the threshold, discrimination, and identification scores. Results Compared to normative data, patients baseline gustatory and olfactory function was impaired. After multimodal treatment, improvements were seen in olfactory function for eight patients (42%), remained stable in 10 patients (53%), and deteriorated in one patient (5%). Taste function remained unchanged following sinus surgery. Conclusions Patients suffering from CRS with polyps exhibit olfactory and taste dysfunctions. Multimodal treatment leads to an improvement in olfactory, but not gustatory functionality. Level of Evidence 4. Laryngoscope, 2017

Purpose In most restaurants or dining facilities, even though a set of condiments such as salt, black pepper, ketchup, and mustard, is placed on the tables, and such condiments are a staple of many cuisines, they have been largely ignored with respect to understanding their effects on food choice. The purpose of this study is to determine whether condiments placed on tables at dining facilities can affect consumers’ cuisine selection. Design/methodology/approach Four individual booths were set up with four different condiment configurations: 1) branded ketchup and mustard, 2) unbranded ketchup and mustard, 3) unbranded soy sauce and chili-garlic sauce, and 4) no condiment. In all, 68 participants were assigned in random sequence to all booths, with each given a menu listing nine different cuisines (three North American, three Asian, and three Hispanic cuisines) in a random order, and asked to identify their top three preferred cuisines at each booth. Findings Participants chose Asian cuisines with higher priority than Mexican and North American selections when Asian condiments were placed on the table. Interestingly, this effect occurred only when the participants had noticed the condiment setting, but not when they had unnoticed it. Such Asian condiment availability-induced cuisine selection was also more pronounced for external eaters. Research limitations/implications Food service professionals and business owners, especially in food courts comprised of a variety of ethnic food vendors, should perhaps consider placing a set of condiments associated with their target cuisines at visible table spaces at dining facilities, thereby leading customers to select their cuisine items. Originality/value This study provides new empirical evidence that consumers are more likely to select cuisines congruent to the choice of condiment setting placed on their dining table.

Objective Recent studies have suggested that patients with obstructive sleep apnea (OSA) might be affected by olfactory impairment. However, more evidence is needed on the effect that OSA has on the chemical senses (olfaction and gustatory) of these patients, and whether continuous positive airway pressure (CPAP) treatment might help to reverse possible impairment. Methods A prospective study was conducted with 44 OSA patients (17 female and 27 male, mean age 54 ± 9.9 years) who were diagnosed via polysomnography and eligible for CPAP treatment. Orthonasal olfactory and gustatory function was measured with the extended Sniffin' Sticks test battery and "taste strips," respectively, before and after CPAP treatment. Results Baseline olfaction was decreased in OSA patients and after CPAP therapy olfactory scores (odor threshold-discrimination-identification score [TDI]: baseline 29.4 ± 4.11 after CPAP 32.3 ± 4.82; p = 0.001; odor threshold [THR]: baseline 5.28 ± 1.69 after CPAP 6.78 ± 2.61; p = 0.000; odor identification [ID]: baseline 12.9 ± 1.95 after CPAP 13.6 ± 1.33; p = 0.013) improved significantly. In contrast, neither baseline taste function in OSA patients nor gustatory function after treatment seemed to be affected. Conclusion Orthonasal olfactory function in patients with OSA improves under CPAP therapy; however, gustatory function is not impaired in OSA patients.

Texture has long been considered an important attribute for food acceptance. However, which specific textural characteristics contribute to overall acceptance of a food is not well understood. It has been suggested that texture contrasts and combinations are a universal feature in giving foods a desirable texture, yet this notion is largely based upon anecdotal data. This study uses multiple survey research methods to assess the importance of texture contrast and combinations across cultures (Poland, U.S.A., and Singapore). Participants (n = 288) completed a survey that included overt measures of food texture contrast importance as well as free response questions regarding texture. The overall importance of texture for food liking was not different across the populations. However, the participants from Singapore and Poland gave more importance to a desirable food having multiple textures than the U.S.A. cohort. When looking at free responses, participants were twice as likely to mention combinations (multiple textures) with a texture contrast when describing foods they liked, in comparison to foods they disliked. This was observed across all 3 cultures. However, the type and quantity of texture terms used within combinations were different among cultures. For instance, Asians enjoyed more texturally diverse food combinations than the other two cultures. These findings highlight the importance of texture contrasts and combinations in three distinct cultures.

Typically, broccoli arrives at the store within 7&ndash, 14 days of harvest and is kept refrigerated until purchased or considered waste. To date, information has been limited on how this time on the shelf or storage temperature affects the sensory attributes that contribute to broccoli purchase or repurchase. In this study, 100 consumers performed acceptance tests and a check-all-that-apply (CATA) section to characterize sensory changes in two cultivars of broccoli (&lsquo, Diplomat&rsquo, and &lsquo, Emerald Crown&rsquo, ) stored at two temperatures (0 &deg, C and 4 &deg, C) over five time points: 0, 14, 21, 28, and 42 days. Due to quality degradation during storage, the overall liking of broccoli decreased regardless of holding temperature and variety. This was in accordance with a decrease in sweetness and an increase in bitterness intensity. However, there were differences between varieties in which Diplomat had more sensory changes at higher temperatures and only Emerald showed negative changes to its appearance in color. Lastly, the CATA data revealed the attributes responsible for modulating the consumer acceptance of broccoli such as tastes, colors and flavors (e.g., grassy, musty, dirt-like). This information can be used to better inform shelf-life determinations of broccoli. Additionally, these changes in taste, odor, texture, and color can inform those interested in investigating the biochemical processes related to broccoli storage.

IntroductionIn daily life, people encounter a wide range of odors, most of which contain multiple chemical substances. So-called bimodal odors stimulate both the olfactory and trigeminal nerve, and the interaction between these two systems shapes the perception of the odor. However, temporal encoding of these sensory systems during bimodal odor processing has received limited scientific attention.MethodsTo investigate this, we recorded the electrophysiological response in 17 participants to relatively unimodal olfactory (strawberry), trigeminal (l-isopulegol) and strongly bimodal (strawberry and l-isopulegol) stimuli.ResultsERP amplitudes and intensity ratings were significantly bigger for bimodal stimulation, as compared to unimodal stimulations. No significant difference was observed between N1 and P2 response latencies to olfactory and bimodal stimuli while responses to both stimuli showed longer latencies compared to the response of the trigeminal stimulus.ConclusionsResults provide further evidence of interaction between olfactory and trigeminal systems; additional activation of the olfactory system results in more vigorous electrophysiological responses and the experience of higher intensity. In addition, results indicate that the trigeminal system is faster to react to stimulation.ImplicationsThe current study offers a view on the temporal processing of bimodal odorants that are most likely to be encountered in the environment. We link the more vigorous electrophysiological response to a more complex odorant with activation of different neural structures.

Background Viral rhinitis (the “common” cold) is a frequent worldwide disease. Olfactory dysfunction is one complication that arises during infection, which in most cases heals up spontaneously upon recovery, whereas in some cases it may persist as a partial or total loss of olfaction. The aim of this prospective study was to investigate the change of other chemosensory systems during a cold. Methods Fifty-eight patients (age 18 to 69 years) with an acute cold were compared to a healthy control group (n = 59; age 19 to 63 years). All patients were examined on 2 occasions separated by approximately 4 weeks. Orthonasal, retronasal, gustatory, and trigeminal nasal function were investigated. Furthermore, ratings of real foods, in terms of intensity and pleasantness, were obtained. Results Compared to the control group, patients showed a decreased orthonasal (threshold and discrimination) and retronasal function. Furthermore, patients exhibited a decreased sensitivity to salt and a reduced ability to localize menthol, indicating a decreased taste and trigeminal function, respectively. Upon recovery from the infection, orthonasal olfactory and trigeminal sensitivity increased, whereas retronasal sensitivity showed no improvement and salt sensitivity decreased. Conclusion This comprehensive study provides empirical evidence that chemosensory impairment is prevalent during a cold, and additionally shows for the first time that chemosensory features associated with food consumption persist postinfection.

A common, lasting condition from traumatic brain injury is impairment to smell. In patients with olfactory impairment, recent meta-analyses have demonstrated that olfactory training consistently improves higher-order functions, such as odor identification. The focus of this work was to assess effects of olfactory training (OT) in posttraumatic olfactory loss patients through several metrics including psychophysical, olfactory bulb (OB) volume, and functional magnetic resonance imaging.Prospective cohort study.Sniffin' Sticks were used to classify two patient groups (anosmic [N = 23] and hyposmic [N = 14]) and measure changes after OT. Additionally patients were asked the intensity, valence, and uncued identification of odors presented (coffee and peach) within the magnetic resonance imaging scanner before and after olfactory training. Olfactory training was performed twice daily with a four-odor training set for 24 weeks, and sets were replaced halfway through the entire training session (~12 weeks).Patients had an increase in test scores (threshold and identification) and in-scanner intensity ratings and identification. Anosmic patients showed improved olfactory thresholds to 2-phenylethanol, increased intensity ratings, and activation in the right superior frontal gyrus (SFG) to odors after OT. Hyposmic patients were able to identify odors better after training. This behavior was mirrored with increased, ipsilateral activations in semantic processing areas such as Broca's area, left angular gyrus, and left SFG.Taken together, along with neither patient group showing changes in OB volumes, OT improves olfactory performance in patients with posttraumatic olfactory loss and seems to be driven, at least in part, by top-down processes (central) rather than bottom-up (peripheral).2 Laryngoscope, 129:1737-1743, 2019.

While it is widely accepted that texture is a multimodal in nature, little research has been published regarding how we use senses other than touch to assess texture. In beverages, humans use texture (i.e. viscosity) information to estimate calories and expected satiety. This study was designed to compare and contrast the sensitivity of humans to changes in viscosity and their ability to estimate satiety through different sensory modalities. Milk samples of varying viscosities were constructed, and 49 participants were asked to perform a series of 2-alternative forced choice tests and identify which sample was thicker. Sensitivity to viscosity changes across different sensory modalities was determined by having each participant consume the samples, listen to the samples pouring, and observe clear vials of the samples. Using vision, participants were notably less sensitive to changes in viscosity when compared to hearing or oral tactile sensations. Interestingly, oral tactile sensations and hearing were almost identical in their viscosity difference thresholds (0.346 cP and 0.360 cP, respectively). Similar patterns were observed when the participants were asked to estimate how full they expected to be after consuming beverage stimuli varying in viscosity. Expected caloric values and satiation were found to change with thickness level when participants were assessing the stimuli through the auditory or tactile modalities. However, these measures of expected caloric value and satiation did not change as a function of viscosity for visual assessment, suggesting the assessment of caloric density and satiation are linked to specific sensory modalities’ ability to detect viscosity. This study highlights the relative importance of vision, auditory, and touch to forming our sensory judgements regarding viscosity and subsequent satiety estimations.

Olfactory habituation results from prolonged exposure to an odor, leading to perceptual changes defined by several characteristics. To date, human habituation research has focused on orthonasal olfaction which is perceived externally while ignoring internal routes of odor perception related to flavor. In our study, we conducted two experiments to characterize retronasal olfactory habituation and measured its impact on flavor perception. In Experiment 1, 22 participants rhythmically breathed a food odor (lime), non-food odor (lavender), and blank (propylene glycol) that was presented using an orally-adhered strip, while rating the odor intensity using the time-intensity procedure. After a 10-minute exposure, the participants ate a lime-flavored gummy and rated the lime flavor. In Experiment 2, the same procedure was performed for a low-level lime odor, a simple (lime oil) and complex (lime oil + sucrose + citric acid) beverage as the flavor stimuli. Our results demonstrated two known principles of habituation for retronasally presented odors: 1) prolonged exposure lead to decreased perception, 2) weaker stimuli lead to more rapid habituation. Additionally, we found that the non-food odor habituated slower than the food odor; however, the participants seemed to recover simultaneously upon food and beverage consumption leading to no change in flavor perception.

Increasing compliance with proper hand washing among consumers and foodservice workers during food handling and preparation is an effective strategy to minimize the spread of bacteria and disease. At home and in the food industry contributing factors and barriers exist that lead to low rates of compliance with proper hand hygiene. Recently, researchers have begun to emphasize the importance of internal motivational factors such as the emotion of disgust and how it affects hygiene behaviors. This study was designed to determine the influence of disgust and other motives on hand washing among participants when handling common foods in the foodservice industry, and if these responses are culturally dependent. A preliminary survey that showed differing levels of consumers' disgust among 21 foods commonly handled in the food industry was conducted. In the main part of the study, representatives from two cultures, Caucasian and Hispanic, were observed while they handled four common foods; apple, bread, chicken and fish. Results from this study showed that hand washing behavior was affected by the type of food being handled and the intensity of the emotion of disgust. Individuals tended to wash their hands more frequently for foods they perceived as more hazardous, and their motives to wash varied among variables of gender (self-protection for men, carryover effects for women), culture (self-protection for Caucasians, texture for Hispanics) and the type of food (self-protection for chicken, smell for fish). Additionally, as the feeling of disgust increased among individuals their probability to wash their hands also increased. Factors that did not show an influence on hand washing included the culture and gender of the participant, and whether they had past foodservice experience. These findings, in combination other studies, should be considered when designing motivation and training strategies to increase consumer or foodservice employee hand washing behaviors.