Odor Identification Research Articles

Clinical efficacy of olfactory training using aromatic traditional Chinese medicine in managing olfactory dysfunction induced by SARS-CoV-2.

The aim of this study is to assess the clinical efficacy of olfactory training using aromatic traditional Chinese medicine (TCM) for addressing severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)-induced olfactory dysfunction, while also exploring the factors that influence the observed efficacy. 172 outpatients with SARS-CoV-2-related olfactory dysfunction were randomized into two groups. The experimental group received olfactory training with TCM aromatics (ginger, Pericarpium Citri Reticulatae, Santali Albi Lignum, Styrax), while the control group used non-TCM aromatics (phenyl ethanol-rose, menthol-mint, citronellal-lemon, eugenol-clove) for 24 weeks. Olfactory function was assessed using the Sniffin' Sticks test and TDI (threshold-discrimination-identification) scores at baseline, 1, 3, and 6 months post-treatment. Response rates at 1, 3, and 6 months post-treatment were 3.66%, 25.61%, and 43.90% in the experimental group, and 4.94%, 23.46%, and 43.21% in the control group. The TDI scores of the experimental group and the control group were statistically different before and after treatment. At 3 and 6 months post-treatment, TDI scores increased significantly, with enhanced odor discrimination and identification capabilities in both groups compared to pre-treatment, while the odor detection threshold was not improved compared with that before treatment. At the 3- and 6-month follow-ups, experimental group showed significantly higher self-rated sleep and anxiety scores than controls, indicating notable improvement in both after treatment. Olfactory training with aromatic TCM offers an effective treatment for SARS-CoV-2-induced olfactory dysfunction, improving odor discrimination, identification without significant differences compared to conventional aromatics, besides, it may also improve anxiety and sleep quality.

Comparison of brief olfactory and cognitive assessments to neuroimaging biomarkers in the prediction of cognitive decline and dementia in the MCSA cohort.

We evaluated impaired odor identification and global cognition as simple, cost-effective alternatives to neuroimaging biomarkers to predict cognitive decline and dementia in the Mayo Clinic Study of Aging. Six hundred forty-seven participants (mean 8.1, standard deviation 3.4 years' follow-up) had the following baseline procedures: modified Blessed Information Memory Concentration Test (BIMCT), 12-item Brief Smell Identification Test (BSIT), structural brain magnetic resonance imaging (MRI), and positron emission tomography (PET) imaging with 11C-Pittsburgh compound B (11C-PiB) and fluorodeoxyglucose (FDG; subset). Cognitive decline developed in 102 participants and dementia in 34 participants. In survival analyses, PiB PET showed robust prediction for cognitive decline. Impaired BSIT, impaired BIMCT, MRI, and FDG measures were also significant predictors. The combination of demographics + BSIT + BIMCT showed strong predictive utility (C-index 0.81), similar to demographics + PiB PET (C-index 0.80). Similar but stronger results were obtained for prediction of dementia. Impairment in both odor identification test and global cognition was comparable to PiB PET for predicting cognitive decline and dementia. In 647 participants in the population-based Mayo Clinic Study of Aging, several clinical markers and biomarkers each predicted cognitive decline or dementia during an average 8 years of follow-up. The combination of the demographic variables of age, sex, and education with a brief odor identification test (BSIT) and a global cognitive test (Blessed Information Memory Concentration Test) showed strong predictive utility (C-index 0.81) for cognitive decline that was similar to the demographic variables combined with Pittsburgh Compound B amyloid imaging (C-index 0.80). Combining a brief odor identification test with a brief cognitive test needs consideration as a simple, cost-effective option in the clinical assessment of individuals at risk of cognitive decline and dementia, as well as a potential tool to identify individuals who may benefit from disease-modifying treatments and to screen participants for prevention trials.

Single-neuron representations of odours in the human brain

Olfaction is a fundamental sensory modality that guides animal and human behaviour1,2. However, the underlying neural processes of human olfaction are still poorly understood at the fundamental—that is, the single-neuron—level. Here we report recordings of single-neuron activity in the piriform cortex and medial temporal lobe in awake humans performing an odour rating and identification task. We identified odour-modulated neurons within the piriform cortex, amygdala, entorhinal cortex and hippocampus. In each of these regions, neuronal firing accurately encodes odour identity. Notably, repeated odour presentations reduce response firing rates, demonstrating central repetition suppression and habituation. Different medial temporal lobe regions have distinct roles in odour processing, with amygdala neurons encoding subjective odour valence, and hippocampal neurons predicting behavioural odour identification performance. Whereas piriform neurons preferably encode chemical odour identity, hippocampal activity reflects subjective odour perception. Critically, we identify that piriform cortex neurons reliably encode odour-related images, supporting a multimodal role of the human piriform cortex. We also observe marked cross-modal coding of both odours and images, especially in the amygdala and piriform cortex. Moreover, we identify neurons that respond to semantically coherent odour and image information, demonstrating conceptual coding schemes in olfaction. Our results bridge the long-standing gap between animal models and non-invasive human studies and advance our understanding of odour processing in the human brain by identifying neuronal odour-coding principles, regional functional differences and cross-modal integration.

Comparative analyses of post-infectious olfactory dysfunction between COVID-19 and non-COVID-19 cases

To identify the differences between COVID-19-associated and non-COVID-19-associated olfactory dysfunction (OD), we analyzed demographic and clinical characteristics based on the causative virus (COVID versus non-COVID groups) in patients with post-infectious olfactory dysfunction (PIOD) who underwent the olfactory questionnaire and olfactory function test. Out of 169 patients with PIOD, 99 were diagnosed with COVID-19 (COVID group), while 70 were not (non-COVID group). The COVID group was younger and had a higher percentage of male patients as well as patients with parosmia than the non-COVID group. In the initial olfactory function tests, the TDI, discrimination and identification scores were significantly higher in the COVID group than in the non-COVID group. TDI scores were significantly increased in patients with PIOD after treatment, regardless of the group. The threshold score was significantly increased by 1.38 in the COVID group while the identification score was significantly increased by 2.67 in the non-COVID group. Patients with COVID-19-associated OD were younger in age, tended to be male, had a higher incidence of parosmia, and had better initial olfactory function test results compared to those with non-COVID-19-associated OD. Following treatment, odor detection threshold improved in the COVID group, whereas odor identification improved in the non-COVID group.

A Rose by Another Name? Odor Misnaming is Associated with Linguistic Properties.

Naming common odors is a surprisingly difficult task: Odors are frequently misnamed. Little is known about the linguistic properties of odor misnamings. We test whether odor misnamings of old adults carry information about olfactory perception and its connection to lexical-semantic processing. We analyze the olfactory-semantic content of odor source naming failures in a large sample of older adults in Sweden (n = 2479; age 58-100 years). We investigate whether linguistic factors and semantic proximity to the target odor name predict how odors are misnamed, and how these factors relate to overall odor identification performance. We also explore the primary semantic dimensions along which misnamings are distributed. We find that odor misnamings consist of surprisingly many vague and unspecific terms, such as category names (e.g., fruit) or abstract or evaluative terms (e.g., sweet). Odor misnamings are often strongly associated with the correct name, capturing properties such as its category or other abstract features. People are also biased toward misnaming odors with high-frequency terms that are associated with olfaction or gustation. Linguistic properties of odor misnamings and their semantic proximity to the target odor name predict odor identification performance, suggesting that linguistic processing facilitates odor identification. Further, odor misnamings constitute an olfactory-semantic space that is similar to the olfactory vocabulary of English. This space is primarily differentiated along pleasantness, edibility, and concreteness dimensions. Odor naming failures thus contain plenty of information about semantic odor knowledge.

Taste and smell are associated with dietary intake, eating behavior, nutritional status, and health-related quality of life in children with cancer

Background & aimsSmell and taste changes are frequently reported bothersome treatment symptoms during treatment for childhood cancer and assumed to influence outcomes such as food intake. Since nutritional status of children with cancer is already vulnerable, any detrimental effects on food intake should be prevented. Therefore, understanding the exact relationship between chemosensory changes and dietary intake, eating behavior, and other domains such as health-related quality of life (HRQoL), is important for improving outcomes. MethodsIn this longitudinal study, we followed 87 childhood cancer patients treated for hematological, solid, or brain malignancies. Smell (odor threshold and odor identification) and taste function (total taste score) were objectively investigated using commercial Sniffin’ Sticks and Taste Strips respectively, and by self-report. Dietary intake was measured using a 3-day food dairy. For nutritional status, BMI expressed as standard deviation scores was derived from medical records. Eating behavior and HRQoL were assessed by the Behavioral Pediatrics Feeding Assessment Scale (BPFAS) and PedsQL 4.0 Generic Core Scales, respectively. Measurements were taken approximately 6 weeks (T0), 3 months (T1), 6 months after starting chemotherapy (T2), and 3 months after termination of chemotherapy or maintenance phase for children with acute lymphoblastic leukemia (ALL) (T3). Dietary intake, eating behavior, nutritional status, and HRQoL were modelled over time using mixed model analysis. Associations between smell and taste (objective and self-report), as well as patient characteries were studied. ResultsEnergy intake significantly increased during the study period, with a higher age, BMI, and total taste scores associated to this increase. Boys had higher energy intake compared to girls. Eating behavior scores significantly declined, indicating less eating problems. Age, pre-diagnosis eating behavior, self-reported smell changes, and tube feeding were associated to eating behavior. BMI significantly increased, with a higher BMI at diagnosis to be related to a higher BMI during the study period. A lower BMI was found in children receiving tube feeding and self-reported taste changes. HRQoL improved during the study period, with lower HRQoL in children receiving tube feeding and self-reported taste changes. ConclusionBoth objective and subjective measures of taste and smell influence dietary intake, eating behavior, nutritional status, and HRQoL. Individual dietary advice and coping strategies are warranted to prevent detrimental effects of chemosensory changes on food intake and clinical outcomes in children with cancer.

A Pilot Study of the Computerized Brief Smell Identification Test

Objectives: A self-administered Computerized Brief Smell Identification Test (cB-SIT) was developed recently to perform the olfactory identification test under computer control. The aim of this study was to evaluate the clinical applicability of the cB-SIT as compared with the traditional Brief Smell Identification Test (B-SIT). Methods: Sixty healthy volunteers with self-reported normal olfactory function, 30 hyposmic patients, and 30 anosmic patients were enrolled from June 2023 to May 2024. All enrolled participants received both B-SIT and cB-SIT in a random order to measure their odor identification ability. Thirty healthy volunteers took the second B-SIT and cB-SIT at least one week later. Results: The score was significantly different in both B-SIT and cB-SIT among healthy volunteers, hyposmic, and anosmic patients. The correct answer rate was significantly different in 10 items of the B-SIT and in 7 items of the cB-SIT among the three groups, but the post hoc test showed significant differences in correct answer rates between healthy volunteers and hyposmic patients in 7 items of both the B-SIT and cB-SIT. Test–retest results showed the score of the second B-SIT test was significantly higher than that of the first test, but the scores of the two tests of the cB-SIT were not significantly different. In the B-SIT, the lemon odorant had a higher correct answer rate in the second test than in the first test, but in the cB-SIT, the correct answer rate was not significantly different between the first and second tests in all 12 items. Conclusions: Our findings demonstrate that the cB-SIT was similar to the B-SIT and can be administered in the diagnosis of patients with olfactory dysfunction.

Effect of Intranasal Insulin on Olfactory Recovery in Patients with Anosmia .

Olfactory dysfunction, defined as either a complete or partial impairment of smell, is a common condition that may substantially affect a person’s quality of life and is frequently difficult to treat. Physical activity, heredity, nutrition, smoking, head trauma, medical treatments, and virus exposure all influence one’s capacity to smell. Hyposmia or anosmia, or loss of smell, affects 3% to 20% of the population. Intranasal insulin can improve cognitive performance, reduce food intake, and boost olfactory thresholds in healthy individuals. As people age, they are more likely to experience olfactory dysfunction, which may be affected by a variety of reasons, such as acute and chronic sino-nasal illness, upper respiratory infections, toxic chemical exposure, and degenerative diseases. About ten percent of those over 65 develop olfactory impairment, which can range from mild loss to total anosmia. Insulin resistance in the central nervous system has been linked to conditions like type II diabetes, Alzheimer’s disease, obesity, and poor odor identification. Reduced odor perception may contribute to reduced olfactory function in anosmic patients.

Olfactory Bulb Volume and Asymmetry as Predictors of Executive Dysfunction in Adolescents with Congenital Heart Disease.

Common sequelae for patients with congenital heart disease (CHD) are neurodevelopmental disabilities including executive function, attention, and socio-emotional deficits. Although these are common diagnoses for patients with CHD, limited research has investigated the mechanistic underpinnings of these findings. Our previous research examined the association between abnormal respiratory ciliary motion and brain abnormalities in infants with CHD. Results suggested that abnormal ciliary motion correlated to a spectrum of subtle dysplasia, notably within the olfactory bulb (OB)1. Our current study investigates whether OB anomalies predict neurodevelopmental outcomes for pediatric patients with CHD. We hypothesize that adolescents with CHD who exhibit aberrant morphological measurements in the OB are more likely to suffer from executive functional deficits. A prospective, observational study of 54 CHD and 75 healthy subjects, ages 6-25 years old, was completed under the supervision of a senior pediatric neuroradiologist. T2 3D Space and T2 Blade 2MM MRI images were manually segmented to extract volumetric bilateral regions of the OB and cerebrospinal fluid (CSF) using ITK-SNAP. Imaging metrics were correlated to OB asymmetry, CSF to OB ratio, total CSF volume, total OB volume, and independent left and right CSF and OB volumes. Linear regression was used to evaluate MRI morphologic measurements with co-variates: CHD status, sex, MRI age, and segmenter. Executive function was determined by the Behavioral Rating Inventory of Executive Function (BRIEF) Parent Report and Delis-Kaplan Executive Function System (D-KEFS) for subjects ages 6-16. Cognition and olfactory function were measured with the NIH Toolbox Cognitive Battery and Odor Identification Test, respectively. No statistically significant results were reported between cohorts for asymmetry of OB, CSF to OB ratio, total CSF volume, total OB volume, nor between independent left and right CSF and OB volumes. Increased OB volume was associated with worse outcomes on the BRIEF Parent Report (p≤0.03). Asymmetry of OB predicted poorer executive functioning as reported by parents on the BRIEF (p≤0.05). Overall, the CHD cohort demonstrated worse scores on the BRIEF Parent Report compared to controls. Across groups, no significant association was reported for olfaction function measured by the NIH Toolbox Odor Identification Test on a limited subset of participants. As survival rates for CHD improve, there is an increased risk of long-term neurodevelopmental impairments. Our findings identify adolescents who are at risk for executive dysfunction, particularly those showing increased OB volume and/or asymmetry of the OB. This is particularly concerning for the CHD population with atypical OB morphology, who also exhibit significantly poorer outcomes on the BRIEF Parent Report and face a higher overall risk. Increased OB volume and OB asymmetry are olfactory-based biomarkers that may help identify at-risk CHD patients earlier, enabling more timely intervention and support.

As a phenomenon: Ramadan fasting improves olfactory performance.

The present study objectived to investigate the influence of Ramadan fasting (RF) on olfactory function. Sixty-two participants were included in the current prospective study. The odor threshold and identification performances were determined by using the Connecticut Chemosensory Clinical Research Center (CCCRC) test initially (day 0) and on the first and last day (30th) of RF. Body weight (BW)s were measured initially and at the end of the study. The results were analyzed statistically. The average of baseline and last-day BWs were 78.38 ± 12.96 and 78.36 ± 12.39 kg, respectively. No significant difference was determined in terms of BWs (p = .932, p > .05). In the evaluation of CCCRC test outcomes, significant differences were observed in the scores of butanol thresholds (p = .0001), odor identification (p = .0001), food-related odors identification (p = .0001), and the number of normosmic individuals (p = .0001) at different times (p < .05). The thresholds scores (p = .0001, p = .0001), the identification scores (p = .0001, p = .0001), food-related odors identification scores (p = .0001, p = .0002), and the number of normomic individuals (p = .001, p = .001) detected on 30th day were significantly higher than on 0th and 1st days; respectively (p < .05). Additionally, the threshold scores (p = .0001), the identification scores (p = .003), food-related odors identification scores (p = .007), and the number of normosmic individuals (p = .018) detected on day 1 were significantly higher than on day 0 (p < .05). The current study demonstrated that Ramadan fasting enhances the olfactory detection threshold and odor identification scores, significantly improving the identification of food-related odors. The results may indicate that Ramadan fasting improves olfactory performance. Level II.

Olfaction and thyroid hormones in patients with subjective cognitive decline, non-amnestic and amnestic mild cognitive impairment.

Thyroid hormones may affect olfaction in different stages of cognitive impairment: subjective cognitive decline (SCD), non-amnestic (naMCI) and amnestic mild cognitive impairment (aMCI). Additionally, biometric parameters, depression, and neuropsychological performance are considered as possible influencing factors. Aretrospective single-center data analysis was conducted during the observation period 2001-2023, with n = 495 (52.3% female) SCD, naMCI and aMCI subjects, aged ≥50years, at the General Hospital of Vienna. The criterion olfactory function was objectively measured by Sniffin' Sticks© odor identification and subjectively through the Assessment of Self-Reported Olfactory Functioning test. Serum thyroid hormone levels, mainly thyroid-stimulating hormone, as well as T3, T4, fT3, and fT4, were used to assess thyroid function. Statistical analyses using IBM SPSS® 29.0.0 covered adjusted multiple linear regression models with hierarchical blocks to predict olfactory performance considering β‑weights. Of the study participants, 4.2% had hypothyroidism and 2.4% had hyperthyroidism. The majority exhibited normal thyroid function. One third (33.5%; 95% confidence interval, CI 29.4-37.0%) were hyposmic. The results indicate no substantial association between thyroid and olfactory functions. Increasing age (β = 0.20), lower performance in the Neuropsychological Test Battery Vienna (NTBV) dimensions verbal memory (β = -0.33) and attention (β = -0.12) appear to be risk factors for lower olfaction. Adiscrepancy between subjective and objective olfaction was found. Thyroid and olfactory functions had no substantial relationship. Higher fT4 correlated weakly with lower odor identification. Increasing age and decreased performance in two out of six NTBV dimensions are relevant prognostic factors for olfactory dysfunction.

Olfactory performance and odor liking are negatively associated with food neophobia in children aged between 3 and 9 years

BackgroundChild food neophobia, i.e., rejection or avoidance of novel foods at a young age, is a prevalent nutrition problem that affects the quality of children’s diet and impedes the development of healthy food preferences. Sensory sensitivity can relate to the degree of food neophobia, but previous studies rarely focused on the olfactory component of this problem in children.ObjectiveWe aimed to thoroughly examine the relationship between various aspects of olfactory sensitivity and food neophobia in children.Methods246 children aged between three and nine years took part in a food neophobia assessment as well as in a comprehensive, psychophysical olfactory testing.ResultsWe found that certain smell perception aspects such as lower odor liking, poorer odor identification ability as well as lower sensitivity to an unknown non-food odor all significantly predicted higher food neophobia in children. Among individual characteristics of either a child or a caregiver, only the child’s age significantly and positively predicted food neophobia. The exploratory model looking into the role of family environment factors predicting self-reported food neophobia in children revealed that food neophobia was associated with lower control given to a child in this child’s feeding process, as well as with a more frequent use of food as a reward in feeding.ConclusionsWe suggest that suppressed olfactory perception and performance can play a unique role in child nutritional difficulties. The study inspires further considerations of olfaction-engaging interventions to counteract food-neophobia in children.

Odor identification dysfunction in late-life depression with suicidal ideation

BackgroundSuicide is more prevalent among older adults compared to younger individuals. Late-life depression (LLD) poses the highest risk for suicide. However, early recognition of suicidal ideation is challenging. Dysfunction in odor identification (OI), a characteristic of LLD, may hold potential for early identification of suicidal ideation. This study aims to compare OI between LLD patients with suicidal ideation (LLD-S) and LLD patients without suicidal ideation (LLD-NS), and examine its relationship with cognitive function. MethodsA total of 262 LLD-NS patients, 63 LLD-S patients, and 316 healthy normal older adults (HOAs) underwent OI testing, standardized clinical interviews, and comprehensive neuropsychological assessments. Results(1) LLD-S patients exhibited lower OI scores and poorer cognitive performance (including global cognition, information processing speed, memory, language, executive function, and visuospatial ability) compared to LLD-NS patients and HOAs. (2) There were interactive effects between suicidal ideation and OI dysfunction, leading to lower scores in information processing speed and visuospatial ability. (3) OI dysfunction mediated the differences in cognition between the LLD-NS and LLD-S groups. LimitationsThe present study was a cross-sectional design. ConclusionsLLD-S patients had worse odor identification than LLD-NS patients and HOAs, suggesting that OI testing could be a valuable approach for identifying suicidal ideation in LLD and screening for suicide risk. The presence of both OI impairment and suicidal ideation was associated with poorer cognitive performance in LLD.

Insight into the mystery of Pheretima smells worse exposed to water: Identification, type, and volatility of stenchy odor

Pheretima is a popular healthy food, but Pheretima and related foods have specific stenchy odor, especially after decocting or warm soaking, the odor is intense, resulting in nausea and vomiting. This indicates that the release of stenchy odor components is intensified when Pheretima was exposed to hot water. It is urgent to study the composition and release pattern of the stenchy odor components of Pheretima. In this study, a series of samples with different odors were prepared by the combination of SFE-CO2 and warm soaking. The results showed that the fishy and smoky odor of Pheretima were heavier, attributed to the components such as dimethyl trisulfide, TMA, and guaiacol. When Pheretima was exposed to hot water, the fishy odor increased sharply. Dimethyl trisulfide and TMA were the key odor components, especially the exposure of TMA increased by 2∼3 times after warm soaking. The volatilization rate of n-hexanal, TMA, dimethyl trisulfide and other components was found to be highly volatile, and the volatilization rate at 75 °C was 2.5 times that at room temperature. This study proved for the first time that stenchy odor substances include two categories: water-soluble and liposoluble. And found that the water-soluble odor components accelerate their exposure and volatilization in warm water, which is the scientific principle of “Pheretima smells worse exposed to water”.

Parosmia in patients with post-infectious olfactory dysfunction in the era of COVID-19-associated olfactory impairment.

Alarge number of patients with olfactory impairment are affected by parosmia or phantosmia. This study aimed to examine the demographic and clinical characteristics of parosmia. We performed aretrospective data analysis of patients consulting at our Smell and Taste Outpatient Clinic. Atotal of 297 patients were included (203 women, mean age44.4 ± 13.7years). Olfactory function was quantified using the "Sniffin' Sticks" composite TDI (odor threshold, determination, and identification) score. The presence of qualitative olfactory impairment was assessed trough medical history and aparosmia questionnaire. Most of the patients showed olfactory impairment after an infection with SARS-CoV‑2 (84%) and were diagnosed with parosmia (49%). Patients with parosmia (PAR) (n = 201) were significantly younger compared to the group without parosmia (noPAR; n = 92) (PAR 43.2 ± 13years vs. noPAR 47 ± 15.1 years, p = 0.03) and had aslightly shorter duration of disease, without reaching statistical significance (PAR 10.3 ± 4.9months, noPAR 13.6 ± 37.6 months, p = 0.23). They also had higher TDI scores (PAR 24.3 ± 7points, noPAR 21.4 ± 8.2points, p = 0.003). Patients affected by parosmia were younger and had abetter olfactory function compared to patients without parosmia.

Identification of Beef Odors under Different Storage Day and Processing Temperature Conditions Using an Odor Sensing System.

This study used an odor sensing system with a 16-channel electrochemical sensor array to measure beef odors, aiming to distinguish odors under different storage days and processing temperatures for quality monitoring. Six storage days ranged from purchase (D0) to eight days (D8), with three temperature conditions: no heat (RT), boiling (100 °C), and frying (180 °C). Gas chromatography-mass spectrometry (GC-MS) analysis showed that odorants in the beef varied under different conditions. Compounds like acetoin and 1-hexanol changed significantly with the storage days, while pyrazines and furans were more detectable at higher temperatures. The odor sensing system data were visualized using principal component analysis (PCA) and uniform manifold approximation and projection (UMAP). PCA and unsupervised UMAP clustered beef odors by storage days but struggled with the processing temperatures. Supervised UMAP accurately clustered different temperatures and dates. Machine learning analysis using six classifiers, including support vector machine, achieved 57% accuracy for PCA-reduced data, while unsupervised UMAP reached 49.1% accuracy. Supervised UMAP significantly enhanced the classification accuracy, achieving over 99.5% with the dimensionality reduced to three or above. Results suggest that the odor sensing system can sufficiently enhance non-destructive beef quality and safety monitoring. This research advances electronic nose applications and explores data downscaling techniques, providing valuable insights for future studies.

The digital scent device 20: an automated, self-administered odor identification test.

Assessing olfactory function is highly significant in clinical practice, particularly in the context of the recent COVID-19 pandemic. Recent approaches in this field emphasize the importance of reducing the time and cost devoted to olfactory testing procedures. Hence, the aim of the present study was to examine the reliability and basic characteristics of Digital Scent Device 20 (DSD-20), an innovative olfactory test consisting of 20 "universal odors", in a European population. A total of 88 participants (mean age = 45.1, SD = 20.3) volunteered for the study. The sample consisted of 37 normosmic controls and 51 dysosmic patients. The correlation between DSD-20 and the total score in Sniffin' Sticks was high (TDI; R = .80, p < .001), and the test correlated with the individual components of the Sniffin' Sticks test. Furthermore, the correlation coefficient between DSD-20 test and retest was very high (R = .88, p < .001), which was additionally confirmed by a Bland-Altman plot. Essential characteristics of the DSD-20 are its simplicity in self-administration, speed of application, portability, and the fact that it can be reused. Overall, the present study confirms previous notions on DSD-20 by demonstrating its high reliability and usefulness in separating patients with hyposmia/anosmia and normosmic controls.

Identification and interaction of the key odorants in Jimo Huangjiu by means of molecular sensory science

Jimo Huangjiu (Chinese yellow rice wine), with its unique burnt odor, serves as a representative of Huangjiu in northern China. To decode the key odorants in Jimo Huangjiu, the volatiles were captured by headspace solid-phase microextraction and solid-phase extraction combined with solvent-assisted flavor evaporation, and analyzed by gas chromatography–mass spectrometry/olfactometry. and comprehensive two-dimensional gas chromatography–time of flight mass spectrometry. A total of 72 odor-active regions were screened, of which 69 odorants were positively identified and quantitated. Thirty-three of them had odor activity value (OAV) ≥ 1. Aroma recombination experiment verified the quantitate results, and 10 odorants were confirmed as key odorants by odor omission text. To further investigate the perceptual interaction of important odorants, 45 binary odor mixtures consisting of 10 selected odorants with OAV ≥ 1 were prepared, resulting that synergies were more likely to occur in odor combinations with similar chemical structures and odor descriptions.

Dense and persistent odor representations in the olfactory bulb of awake mice.

Recording and analysis of neural activity is often biased toward detecting sparse subsets of highly active neurons, masking important signals carried in low magnitude and variable responses. To investigate the contribution of seemingly noisy activity to odor encoding, we used mesoscale calcium imaging from mice of both sexes to record odor responses from the dorsal surface of bilateral olfactory bulbs (OBs). The outer layer of the mouse OB is comprised of dendrites organized into discrete "glomeruli", which are defined by odor receptor-specific sensory neuron input. We extracted activity from a large population of glomeruli and used logistic regression to classify odors from individual trials with high accuracy. We then used add-in and drop-out analyses to determine subsets of glomeruli necessary and sufficient for odor classification. Classifiers successfully predicted odor identity even after excluding sparse, highly active glomeruli, indicating that odor information is redundantly represented across a large population of glomeruli. Additionally, we found that Random Forest feature selection informed by Gini Inequality (RFGI) reliably ranked glomeruli by their contribution to overall odor classification. RFGI provided a measure of "feature importance" for each glomerulus that correlated with intuitive features like response magnitude. Finally, in agreement with previous work, we found that odor information persists in glomerular activity after odor offset. Together, our findings support a model of olfactory bulb odor coding where sparse activity is sufficient for odor identification, but information is widely, redundantly available across a large population of glomeruli, with each glomerulus representing information about more than one odor.Significance statement This study leverages meso-scale imaging and machine learning to investigate how odor information is first represented in the brain. Typically, recordings of neuronal activity focus on active individual cells, potentially overlooking broader variations in neuronal responses across populations. Our results demonstrate that a considerable amount of olfactory information is redundantly distributed across a large proportion of olfactory bulb glomeruli. Even after excluding a majority of glomeruli, odor identification remained possible. These findings indicate that, although a few glomeruli are sufficient for odor recognition, an abundance of additional information is represented across a broad population. Understanding how the brain manages redundant olfactory information will shed light on its adaptive mechanisms for navigating diverse real-world circumstances and responding to fluctuating internal states.

Reduced odor identification linked to long-term air pollution exposure: findings from the KORA FIT study in Augsburg, Germany

Reduced odor identification linked to long-term air pollution exposure: findings from the KORA FIT study in Augsburg, Germany