Odor Recognition Research Articles

Revealing the off-flavors in hydro-distilled essential oils of sweet orange (Citrus sinensis) by flavoromics strategy and computational simulation

Citrus essential oils (EOs) are renowned for their aroma, but thermal extraction methods can introduce undesirable cooking and pungent odors. The specific compounds responsible for these off-flavors and their perception mechanisms remain unclear. This study investigated the flavor differences between cold pressing (CP) and hydro-distilled (HD) extracted essential oils from sweet oranges (SEOs) using flavoromics strategy. The results indicated that increased levels of alcohol compounds, particularly terpinen-4-ol, β-citronellol, geraniol, trans-carveol, and α-terpineol, were primarily responsible for the off-flavors in HD-extracted SEOs. Furthermore, molecular docking and dynamics simulations revealed that off-flavor compounds bind to olfactory receptors through hydrogen bonding and hydrophobic interactions, inducing slight structural and conformational changes that facilitate odor recognition and activate downstream signaling events. This study offers crucial insights into the mechanisms underlying off-flavor development in citrus EOs, providing valuable knowledge for optimizing extraction methods, controlling SEOs quality, and advancing flavor science.

A Drosophila-inspired intelligent olfactory biomimetic sensing system for gas recognition in complex environments

The olfactory sensory system of Drosophila has several advantages, including low power consumption, high rapidity and high accuracy. Here, we present a biomimetic intelligent olfactory sensing system based on the integration of an 18-channel microelectromechanical system (MEMS) sensor array (16 gas sensors, 1 humidity sensor and 1 temperature sensor), a complementary metal‒oxide‒semiconductor (CMOS) circuit and an olfactory lightweight machine-learning algorithm inspired by Drosophila. This system is an artificial version of the biological olfactory perception system with the capabilities of environmental sensing, multi-signal processing, and odor recognition. The olfactory data are processed and reconstructed by the combination of a shallow neural network and a residual neural network, with the aim to determine the noxious gas information in challenging environments such as high humidity scenarios and partially damaged sensor units. As a result, our electronic olfactory sensing system is capable of achieving comprehensive gas recognition by qualitatively identifying 7 types of gases with an accuracy of 98.5%, reducing the number of parameters and the difficulty of calculation, and quantitatively predicting each gas of 3–5 concentration gradients with an accuracy of 93.2%; thus, these results show superiority of our system in supporting alarm systems in emergency rescue scenarios.

A Short Glance at the Role of Olfactory Tubercle in Odour Processing

ABSTRACTThe mammalian olfactory system is one of the most precocious sensory systems during development and is innately endowed with versatile functions distinct from other sensory systems. Perception of time‐locked olfaction‐related stimuli quickly from the external environment and encoding them accurately via the olfactory system is paramount for the survival and reproduction in the animal kingdom. The olfactory system of mammals encompasses the main and accessory parts. As one key component of the ventral striatum, the olfactory tubercle (OT), is also an important as well as indispensable sub‐region of the main olfactory system and plays a crucial role in the central processing of odours. The OT also serves as a hub linking the olfactory system with the reward system in the brain. Although extensive research has underscored the involvement of the ventral striatum in the reward and punishment process as well as motivational behaviour, the encoding mechanism of neural circuits engaged in odour detection and recognition by the OT is still largely unknown. Herein, we make a brief overview of the olfactory system and underscore the crucial role of olfactory receptors in odour detection. We also emphasize the structural and functional characterisations of the OT and corresponding neural circuits involved in odour processing.

Three-dimensional reconstruction of insect chemosensory sensillum

The olfactory system is involved in food and mate recognition in insects. However, 3D structures of chemosensory sensilla in insects are unexplored yet. Here, the internal structures of an olfactory sensillum on the antenna of the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae), one of the most important rice pests, are examined and imaged using focused ion beam scanning electron microscopy. Based on these images, a 3D structure is reconstructed in this study. We find that the trichoid olfactory sensillum possesses a multiporous wall encircling a lumen with one sensory cell. Besides, there are three accessory cells (ACs) and a glia cell with different cell contents surrounding the sensory cell. The abundant tubular membrane structures in the tormogen cell suggest its role in secreting proteins like odorant binding proteins into the receptor lymph, while three auxiliary cells with simpler cellular content closely enfold the sensory cell, probably to prevent leaking of the receptor lymph into the surrounding epidermis. In the sensory cell, the microtubules and two tandem basal bodies at the base of the microtubules are also reconstructed. They are considered as a propulsive engine to ensure dendrite vibration or spinning in the receptor lymph, so that the proteins and odorant molecules move faster in the receptor lymph, which improves recognition of environmental odors and enables the insect to immediately respond to this information.

ScentClue: Enhancing Story Engagement in Virtual Reality Through Hedonically Varied Olfactory Hints

To enhance the engagement and significance of olfaction as a novel medium in multimedia systems, we aim to integrate different hedonic odorous cues into narratives to augment immersion in virtual experiences. We introduce the ScentClue system, comprising (1) an original and murder-themed experimental film incorporating four distinct hedonic odor cues synchronized with audiovisual elements, (2) a neck-worn scent delivery device capable of dispensing four different odors, and (3) an Unreal Engine-based virtual cinema environment enabling rapid control of video playback and odor dissemination. Experimenting with 18 participants divided into control groups with and without odor stimuli, we validated the system’s usability and effectiveness of odor cue settings. Furthermore, we found that the use of odors with different hedonic qualities could enhance odor recognition, amplify thematic story ambiance, and aid in the rapid differentiation of complex relationships. Finally, we discussed expanded scenarios and interaction modalities for ScentClue, proposing future narrative-driven olfaction-enhanced multimedia designs with considerations for odor cue settings, odor material selection, and scent-releasing setup, particularly unpleasant odors.

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.

Investigating social communication in mice: A two-intruders test approach.

Understanding the complex dynamics of social communication behaviors, such as exploration, communication, courtship, mating, and aggression in animal models, is crucial to reveal key neural and hormonal mechanisms underlying these behaviors. The two-intruders test is designed to investigate residents' behavior toward both male and female intruders within the home cage of the test male. During this test imitating natural conditions, several aspects of social interaction were investigated: Exploration, courtship, mating, and aggressive behavior. As mating and aggression involve overlapping neural circuits, the behavioral setup testing both behaviors is best at reflecting their competitive nature. Our findings demonstrate that resident male mice exhibit strong preference to communicate with a female intruder, which correlates with baseline testosterone levels of test males. Relevant female preference in the two-intruders test was also found in BALB/c males. Behavioral breakdown revealed the anogenital sniffing as a key behavioral feature that discriminates resident male behavior toward intruders of different sex. Furthermore, resident male interaction with female intruder was accompanied by neuronal activation in the ventromedial hypothalamus. We demonstrate that odor recognition underlies preference toward females in male residents, as experimental anosmia reduced communication with a female intruder. We conclude the two-intruders test setup to be a useful tool to study the neurological basis of social communication in animal models, which provides detailed analysis of various aspects of the laboratory animals' social behavior in the most natural conditions.

Thermal Modulation of Resistance Gas Sensor Facilitates Recognition of Fragrance Odors

Herein, we prepared two different MOS-based gas sensors with integrated micro-hotplates. The two sensors were employed to detect various fragrances (cedar, mandarin orange, rose A, and rose B), exhibiting similarly great sensing performances. The gas sensing properties of the MOS-based sensor depend on the sensor’s operating temperature. In addition to isothermal operation, various pulse heating modes were applied to investigate the gas sensing performances with respect to the four fragrances. Multivariate gas sensing features of the four fragrances were obtained under different operating modes, which were utilized for the recognition of fragrance odors successfully, based on the long short-term memory (LSTM) algorithm.

Интерфейсы «мозг–компьютер» и «мозг–мозг» в структуре конвергирующих технологий (на основе экспериментальных данных НИТЦ нейротехнологий ЮФУ)

The article presents a conceptual analysis of the main directions and methods of studying the human psyche, consciousness and brain in contemporary domestic and foreign research. The concept of “converging technologies” is considered in context of the creation of Artificial General Intelligence (AGI). It describes programs for the neuroscientific study of organization of psychic processes in the field of visualization of brain processes and the mapping method, which helps to understand how different parts of the brain can be structurally and functionally separated from each other. The publication pays special attention to understanding the possible use of Brain-Computer Interfaces (BCI) and Brain-to-Brain Interfaces (BMI) in the creation of AGI, “hybrid intelligence”. Brain interfaces are presented as fundamentally new channels of communication and control. An example of a biohybrid odor recognition system developed at the Research Center of Neurotechnology of the Southern Federal University is given. We are talking about the implementation of control through the BMI and mental commands of a bio­logical object – a rat. From the position of a body-oriented approach this work reveals the prob­lem of co-evolution of the body, consciousness, technology and social environment in the post-non-classical paradigm. It is concluded that modern neuroscience has a significant impact on understanding the functioning of the human brain, consciousness and cognitive processes. The feasibility of studying the possible use of BCI and BMI technologies in stimulating brain areas to create sensations equivalent to touch, etc. is noted. We are also talking about the use of biohybrid systems controlled through BMI technology as systems that combine the advan­tages of natural and artificial intelligence (with further elaboration of ethical issues).

Olfactory EEG induced by odor: Used for food identification and pleasure analysis

As the need for food authenticity verification increases, sensory evaluation of food odors has become widely recognized. This study presents a theory based on electroencephalography (EEG) to create an Olfactory Perception Dimensional Space (EEG-OPDS), using feature engineering and ensemble learning to establish material and emotional spaces based on odor perception and pleasure. The study examines the intrinsic connection between these two spaces and explores the mechanisms of integration and differentiation in constructing the OPDS. This method effectively visualizes various types of food odors while identifying their perceptual intensity and pleasantness. The average classification accuracy for odor recognition in an eight-category experiment is 96.1%. Conversely, the average classification accuracy for sensory pleasantness recognition in a two-category experiment is 98.8%. The theoretical approach proposed in this study, based on olfactory EEG signals to construct an OPDS, captures the subtle perceptual differences and individualized pleasantness responses to food odors.

Difficulties with Odor Recognition Threshold Measurement Methods in T&T Olfactometry as Reported by Patients: A Survey

Difficulties with Odor Recognition Threshold Measurement Methods in T&T Olfactometry as Reported by Patients: A Survey

Intelligent Detection and Odor Recognition of Cigarette Packaging Paper Boxes Based on a Homemade Electronic Nose.

The printing process of box packaging paper can generate volatile organic compounds, resulting in odors that impact product quality and health. An efficient, objective, and cost-effective detection method is urgently needed. We utilized a self-developed electronic nose system to test four different cigarette packaging paper samples. Employing multivariate statistical methods like Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), Statistical Quality Control (SQC), and Similarity-based Independent Modeling of Class Analogy (SIMCA), we analyzed and processed the collected data. Comprehensive evaluation and quality control models were constructed to assess sample stability and distinguish odors. Results indicate that our electronic nose system rapidly detects odors and effectively performs quality control. By establishing models for quality stability control, we successfully identified samples with acceptable quality and those with odors. To further validate the system's performance and extend its applications, we collected two types of cigarette packaging paper samples with odor data. Using data augmentation techniques, we expanded the dataset and achieved an accuracy rate of 0.9938 through classification and discrimination. This highlights the significant potential of our self-developed electronic nose system in recognizing cigarette packaging paper odors and odorous samples.

Determining Ultra-Low Organic Molecular Odor Thresholds in Air Helps Identify the Most Potent Fungal Aroma Compound.

The determination of odor threshold values can be performed in various matrices, including air, and serves as a parameter to compare the potencies of odorous compounds. Typically, the odor thresholds in air are determined by gas chromatography-olfactory (GC-O) and referenced to an internal standard, most often (E)-dec-2-enal. Herein, a direct gas chromatography-flame ionization detector-olfactory analysis method for the determination of odor thresholds in air is reported. As model substrates for this novel approach, naturally occurring substances (R)-1-p-menthene-8-thiol as well as (3S,3aS,6R,7aS)-3,6-dimethyl-3a,4,5,6,7,7a-hexahydro-3H-1-benzofuran-2-one were used. The latter compound was synthesized from (-)-isopulegol and exhibited an extremely low odor recognition threshold of 1.9 × 10-6 ng L-1 air, the lowest value reported for a fungal aroma compound thus far.

One-trial odour recognition learning and its underlying brain areas in the zebrafish

Distinguishing familiar from novel stimuli is critical in many animals’ activities, and procedures based on this ability are among the most exploited in translational research in rodents. However, recognition learning and the underlying brain substrates remain unclear outside a few mammalian species. Here, we investigated one-trial recognition learning for olfactory stimuli in a teleost fish using a behavioural and molecular approach. With our behavioural analysis, we found that zebrafish can learn to recognise a novel odour after a single encounter and then, discriminate between this odour and a different one provided that the molecular structure of the cues is relatively differentiated. Subsequently, by expression analysis of immediate early genes in the main brain areas, we found that the telencephalon was activated when zebrafish encountered a familiar odour, whereas the hypothalamus and the optic tectum were activated in response to the novel odour. Overall, this study provided evidence of single-trial spontaneous learning of novel odours in a teleost fish and the presence of multiple neural substrates involved in the process. These findings are promising for the development of zebrafish models to investigate cognitive functions.

Alterations in KIDINS220/ARMS Expression Impact Sensory Processing and Social Behavior in Adult Mice.

Kinase D-interacting substrate of 220 kDa (Kidins220) is a transmembrane protein that participates in neural cell survival, maturation, and plasticity. Mutations in the human KIDINS220 gene are associated with a neurodevelopmental disorder ('SINO' syndrome) characterized by spastic paraplegia, intellectual disability, and in some cases, autism spectrum disorder. To better understand the pathophysiology of KIDINS220-linked pathologies, in this study, we assessed the sensory processing and social behavior of transgenic mouse lines with reduced Kidins220 expression: the CaMKII-driven conditional knockout (cKO) line, lacking Kidins220 in adult forebrain excitatory neurons, and the Kidins220floxed line, expressing constitutively lower protein levels. We show that alterations in Kidins220 expression levels and its splicing pattern cause impaired response to both auditory and olfactory stimuli. Both transgenic lines show impaired startle response to high intensity sounds, with preserved pre-pulsed inhibition, and strongly reduced social odor recognition. In the Kidins220floxed line, olfactory alterations are associated with deficits in social memory and increased aggressive behavior. Our results broaden our knowledge of the SINO syndrome; understanding sensory information processing and its deviations under neuropathological conditions is crucial for devising future therapeutic strategies to enhance the quality of life of affected individuals.

Effect of wearing masks on odor detection and recognition

Background The effect of wearing masks on olfaction remains unclear. Objectives This study aimed to clarify the differences between the effects of no masks, surgical masks, and N95 respirator masks by conducting both identification and threshold olfaction tests. Methods Young, healthy volunteers aged ≥ 18 years and < 30 years without awareness of apparent olfactory disorder were included. All participants filled out a questionnaire on olfaction and completed an acuity smell identification test (Open Essence test) and an olfactory threshold test (T&T olfactometry) while wearing no masks, surgical masks, or N95 respirator masks. Results In the Open Essence tests, the no-mask group score was significantly higher than those of the surgical- and N95-mask groups. Using T&T olfactometry, the median-detection threshold of the no-mask group was significantly lower than that of the surgical-mask group, and the surgical-mask group threshold was significantly lower than that of the N95-mask group. Similar patterns were observed for the median-recognition threshold. Conclusions Wearing masks, especially an N95 mask, reduces the ability to detect and identify odors. This disadvantage should be considered by professionals such as healthcare workers, who require proper olfaction to perform appropriate tasks.

A post-Thanksgiving odor and serious recognition for silly names

A post-Thanksgiving odor and serious recognition for silly names

Sniffing Like a Wine Taster: Multiple Overlapping Sniffs (MOSS) Strategy Enhances Electronic Nose Odor Recognition Capability.

As highly promising devices for odor recognition, current electronic noses are still not comparable to human olfaction due to the significant disparity in the number of gas sensors versus human olfactory receptors. Inspired by the sniffing skills of wine tasters to achieve better odor perception, a multiple overlapping sniffs (MOSS) strategy is proposed in this study. The MOSS strategy involves rapid and continuous inhalation of odorants to stimulate the sensor array to generate feature-rich temporal signals. Computational fluid dynamics simulations are performed to reveal the mechanism of complex dynamic flows affecting transient responses. The proposed strategy shows over 95% accuracy in the recognition experiments of three gaseous alkanes and six liquors. Results demonstrate that the MOSS strategy can accurately and easily recognize odors with a limited sensor number. The proposed strategy has potential applications in various odor recognition scenarios, such as medical diagnosis, food quality assessment, and environmentalsurveillance.

Predator recognition learning by northern redbelly dace Chrosomus eos from a small kettle lake with a dynamic predator community

Predation, and the risk of predation, shape the ecology, behavior, and evolution of many species. Small fishes navigate a perilous landscape of risk in the shallow waters of the littoral zone. Moreover, in small lakes, the predator community can be dynamic due to stochastic colonization and extirpation events. These conditions select for the ability by small fish to acquire recognition of novel predators through associative learning. Chemical cues associated with predation events, such as damage-released chemical cues from conspecifics, and the odor of predators, inform prey of the presence of risk, and facilitate acquired recognition of novel predator odor. Deming Lake, MN, is a small meromictic lake with intermittent connections to neighboring lakes in the watershed. Annual sampling of the littoral fish community between the years 2000 and 2023 reveals a history of colonization and extirpation by relatively large-bodied species such as yellow perch Perca flavescens and pumpkinseed sunfish Lepomis gibbosus. Ice cover data, combined with limnological depth profiles of dissolved oxygen, confirm that dissolved oxygen is limiting during the winter and consistent with the hypothesis that extirpation of large-bodied species in Deming Lake is likely due to winter anoxia. These data set the stage for an experimental demonstration of acquired recognition of the odor of allopatric rock bass Ambloplites rupestris by bass-naïve northern redbelly dace Chrosomus eos from Deming Lake. Rock bass have been absent from Deming Lake since at least the year 2000. Predator-recognition learning allows redbelly dace, and many other small-bodied fishes that face variable predator species over ontogenetic, spatial, and temporal scales, a mechanism to adapt quickly to indicators of predation risk.

Treatment with AV‐001, an Angiopoietin‐1 mimetic peptide, improves dementia outcomes in rats

AbstractBackgroundVascular dementia (VaD) is a complex neurodegenerative disease affecting cognition and memory. We investigated the neurocognitive outcomes of multiple‐microinfarct (MMI) dementia in aged female rats. We previously found that treatment with AV‐001, a Tie2 receptor agonist, significantly improves memory and preference for social novelty in middle‐aged male rats subjected to MMI. In this study, we tested the therapeutic effects of AV‐001 in aged female rats subjected to MMI.MethodFemale, Wistar, rats were aged to 18m and randomly assigned to Sham, MMI, and MMI+1µg/Kg AV‐001 treatment groups (n = 8‐9/group). MMI was induced by injecting either 1000 (low dose, LD‐MMI) or 6000 (high dose, HD‐MMI), 70‐100µm sized cholesterol crystals into the internal carotid artery. AV‐001 treatment (1µg/Kg, i.p.) was initiated at 1d after MMI and administered once daily. A battery of neuro‐cognitive tests was performed at 21‐28d MMI.ResultLD‐MMI induces significant (p&lt;0.05) neurological deficits evaluated using the modified neurological severity score (mNSS) test, starting at 1d after LD‐MMI and persisting at least up to 28d after LD‐MMI. Treatment of LD‐MMI with AV‐001 significantly improves neurological function at 21d and 28d after LD‐MMI compared to LD‐MMI control rats. Aged female rats subjected to LD‐MMI exhibit long term memory impairment in an olfactory learning based novel odor recognition test and a significantly lower preference for social novelty in the three‐chamber social test, although there were no changes in overall preference for sociability compared to Sham rats. Treatment of LD‐MMI with AV‐001 significantly improves long‐term memory and preference for social novelty compared to LD‐MMI control rats. HD‐MMI in aged female rats induces significant anxiety‐ and depression‐like behavior with increased freezing time in the open field test and decreased time spent in the open arms of the elevated plus maze compared to Sham rats. Treatment of HD‐MMI with AV‐001 significantly reduces anxiety like behavior indicated by increased time spent in the open arms of the elevated plus maze compared to HD‐MMI control rats.ConclusionAV‐001 is a novel therapeutic agent that may improve neurological deficits, memory impairment, and anxiety like behavior in aged female rats subjected to a MMI model of vascular dementia.