Search Results (630)

Olfaction is crucial for ducks, influencing essential behaviors such as foraging and mating. However, the molecular basis of sex-associated variation in duck olfactory tissues remains poorly understood. Here, we performed bulk RNA-seq on turbinate tissue from male and female Tianfu Nonghua Mottled Ducks (Anas platyrhynchos domesticus Linnaeus, 1758; Anatidae) to characterize sex-biased transcriptional programs. Our results suggest strong global transcriptomic separation between males and females, with 1906 differentially expressed genes (DEGs) identified. These DEGs were enriched in pathways related to neuronal signaling, cell adhesion, and extracellular matrix organization, suggesting coordinated sex-associated differences in signaling and tissue-organization programs. While olfactory receptor (OR) and trace amine-associated receptor (TAAR) genes showed limited sex-biased expression in bulk tissue, two neuromodulatory GPCRs, TACR2 and DRD4, were prioritized as hub genes within sex-biased co-expression networks. Notably, both genes also showed relatively high expression in turbinate tissue and neuroendocrine centers in an integrated multi-tissue transcriptomic dataset, nominating them as candidate targets for future functional and cell-type-resolved investigations. Overall, our study provides a descriptive molecular profile of sex-biased transcription in duck turbinate tissue, laying a foundation for follow-up studies and potential applications in poultry breeding and management. Full article

Olfaction plays a central role in mammalian social behavior, yet its contribution to group coordination remains poorly understood. Here, we show that olfactory impairment in adult C57BL/6J mice (Mus musculus) leads to the spontaneous emergence of structured group behavior not observed in controls. Mice with disrupted olfactory input consistently engaged in close-contact interactions that increased over time. We quantified these events and found that aggregation occurred significantly more often than expected by chance, with olfaction-impaired mice exhibiting coordinated dyadic, triadic, and quartet configurations that were spatially enriched, temporally stable, and showed consistent patterns of progression between the states. Unsupervised behavioral modeling revealed that these formations were preceded by structured approach and stationing behaviors. Our findings suggest that olfactory input is a key contributor to maintaining typical social dynamics, and that its absence may lead to altered patterns of group interaction potentially driven by reduced sensory input. This work positions olfaction as a key scaffold for social structure and offers a novel framework for understanding how animals adapt to sensory loss in complex group settings. Full article

Volatile organic compounds (VOCs) are increasingly recognized as metabolic byproducts of viral infection and may serve as olfactory cues detectable by trained scent dogs. This study examined whether dogs could distinguish cell culture samples infected with murine hepatitis virus strain 1 (MHV-1), a biosafety level 2 coronavirus model, from uninfected controls. Parallel chemical analysis using gas chromatography–mass spectrometry (GC-MS) identified 14 VOCs in infected and 12 in control samples. Notably, 3-heptanone and 1-nonanol were unique to infected samples, while others such as acetophenone, nonanal, decanal, and benzaldehyde were significantly elevated—often by 1.5 to 3 times—in infected cultures. Two trained dogs demonstrated high detection sensitivity (0.95) for infected samples compared to a previously trained odor cinnamon group (0.88) and responded with shorter latency (p = 0.04), suggesting perceptual salience of infection-related VOCs. Reliable detection required pooled volumes (~600 µL), suggesting a threshold effect related to VOC concentration. Additionally, a Random Forest-based machine learning classifier trained on the GC-MS-obtained VOC profiles achieved a cross-validated accuracy of 0.82 (SD = 0.25). These findings suggest that dogs use quantitative VOC differences, rather than unique compounds, for detection. The study provides a validated experimental framework for olfactory diagnostics of viral infections and highlights the potential of scent dogs as non-invasive biosensors in both veterinary and public health contexts. Full article

Chemosensory proteins (CSPs) are found in the olfactory sensory organs (antennae and maxillary palps) and/or gustatory sensory organs (labellum and legs) and have long been accepted to function through the binding of odorants. However, the same CSPs are also expressed in many tissues other than olfactory and gustatory organs, such as the gut, brain, fat body, wing, epidermis, Corpora allata, salivary gland, pheromone gland, prothoracic gland, etc. In this report, we suggest renaming the “chemosensory protein (CSP)” the “4-Cysteine Soluble Protein (4CSP)”. This paradigm and nomenclature shift is based on molecular characteristics, genomic mining, tissue distribution, and functional roles beyond those related to olfaction. We examined prior studies on this protein gene family to bolster the renaming, highlighting the most recent findings that we ascribe to “pleiotropic properties” and evolutionary relevance rather than smell. The scope of the report, per se, is broad, and this is especially true given the volume of data that has been gathered on 4CSP expressed in ways that are not consistent with the olfactory paradigm. Statements outlining the many chemosensory properties of 4CSPs, particularly how they activate olfactory receptor neurons (ORNs), are currently scarce, if they exist at all. Many debates currently focus on 4CSPs’ non-chemosensory functions, which are backed by a multitude of evidence, from gene evolution to tissue distribution. Therefore, strong arguments in favor of renaming chemosensory proteins are becoming evident here, outweighing the drawbacks. Full article

The endocannabinoid system is a ubiquitous neuromodulatory network that links internal physiological state to neural circuit function across the brain. While its roles in memory, reward, pain, and motor control are well established, its contribution to olfactory processing has only recently gained attention. This review synthesizes the current knowledge on the anatomical, cellular, and functional interactions between the endocannabinoid system and the olfactory pathway, from the olfactory epithelium and main olfactory bulb to higher order cortical targets. We highlight how endocannabinoid signaling, primarily via cannabinoid receptor type 1 (CB1), shapes synaptic transmission within olfactory bulb microcircuits, modulates centrifugal feedback, and adjusts sensory gain in a state-dependent manner, particularly in relation to hunger, feeding behavior, stress, and reward. In addition, we review evidence that the endocannabinoid system regulates olfactory neurodevelopment and adult neurogenesis by influencing neural stem cell proliferation, migration, and integration into existing circuits. Emerging links between endocannabinoid signaling, olfactory dysfunction, neuropsychiatric disease, metabolic disorders, and neurodegeneration underscore the translational relevance of this system. We also discuss methodological challenges inherent to studying endocannabinoid signaling and outline future directions, including circuit-specific targeting and intranasal delivery strategies. Together, these findings position the olfactory system as a powerful and accessible model for understanding how endocannabinoids couple internal state to perception and behavior, with important implications for therapeutic development. Full article

To establish the best approach for conserving a species, it is necessary to understand the biology of that species. To better understand the behavior of American black bears (Ursus americanus), we observed 246 black bears for 7950 h in nature over a 24-year period to quantify how the bears communicated. Black bears communicated using several different behaviors. These included thirteen types of vocalizations, eight olfactory behaviors, eight marking behaviors, sixteen different body postures and gestures constituting their body language, and various emotional expressions. Some behaviors appeared to be automatic, including facial expression, ear movements, some forms of body language, the intensity of various vocalizations, and various moans. Other behaviors appeared to be intentional, including mechanically generated sounds and actions that could be used to bluff or deceive, such as the chomping of teeth, huffing, swatting, false charging, and various vocalizations. The conservation of black bears can be improved by establishing management strategies that take into account the vocal and non-vocal communication of the bears. Conflicts and negative encounters between humans and bears can be reduced through behavioral modifications by humans based on our new understanding of the communication system of bears. Knowledge of the communication system of the black bear provides a basis for improved conservation through the non-lethal management of bears involved in bear–human conflicts. Full article

Dogs show exceptional olfactory sensitivity and are widely used in medical, rescue, military, and forensic applications, yet the determinants of individual and breed-level scent-work performance remain incompletely characterized. This review integrates evidence from the anatomy and physiology of the canine olfactory organ, neurobiological mechanisms of odor transduction and coding, and links between olfaction, memory, and emotion, alongside molecular genetics, evolution, domestication, and selective breeding. We synthesize findings indicating that complex nasal turbinates and specialized airflow patterns enhance odorant capture, while olfactory bulb circuitry and downstream connections to limbic and frontal networks support discrimination, learning, and affective modulation. Comparative and breed-focused studies suggest that skull morphology and breeding priorities can alter olfactory capacity, with shortened nasal anatomy associated with reduced functional potential in some lines. In applied contexts, detection success is strongly shaped by behavioral traits such as motivation, persistence, independence, and reward value, as well as by physical condition and environmental stressors that can impair search efficiency. Emerging literature further suggests that the gastrointestinal and upper airway microbiome, together with diet, housing, temperature, and workload, may influence sensory and cognitive readiness, although direct causal links to detection outcomes remain limited. Overall, canine olfactory performance reflects interactions among genetic–anatomical capacity, neurobehavioral factors, and environment, underscoring the value of standardized selection, training, welfare management, and future integrative research. Full article

In this study, we describe a non-invasive approach to objectively assess fragrance-induced emotions using multiplex salivary biomarker profiling. Traditional self-reports, physiological monitoring, and neuroimaging remain limited by subjectivity, invasiveness, or poor temporal resolution. Saliva offers an advantageous alternative, reflecting rapid neuroendocrine changes linked to emotional states. We combined four key salivary biomarkers, cortisol, alpha-amylase, dehydroepiandrosterone, and oxytocin, to capture multidimensional emotional responses. Two clinical studies (n = 30, n = 63) and one user study (n = 80) exposed volunteers to six fragrances, with saliva collected before and 5 and 20 min after olfactory stimulation. Subjective emotional ratings were also obtained through questionnaires or an implicit approach. Rigorous analytical validation accounted for circadian variation and sample stability. Biomarker patterns revealed fragrance-induced emotional profiles, highlighting subgroups of participants whose biomarker dynamics correlated with particular emotional states. Increased oxytocin and decreased cortisol levels aligned with happiness and relaxation; in comparison, distinct biomarker combinations were associated with confidence or dynamism. Classification and Regression Trees (CART) analysis results demonstrated high sensitivity for detecting these profiles. Validation in an independent cohort using an implicit association test confirmed concordance between molecular profiles and behavioral measures, underscoring the robustness of this method. Our findings establish salivary biomarker profiling as an objective tool for decoding real-time emotional responses. Beyond advancing affective neuroscience, this approach holds translational potential in personalized fragrance design, sensory marketing, and therapeutic applications for stress-related disorders. Full article

Chronic pain is inherently multifactorial, with biological, psychological, and social factors contributing to neuropathic pain (NP) and central sensitization (CS) syndromes. Comorbidity between functional disorders and the lack of clinical biomarkers adds to the challenge of diagnosis and treatment, leading to frustration for healthcare professionals and patients. Available treatments are limited, increasing patient suffering with personal and financial costs. This systematic review examined multisensory processing alterations in chronic pain and reviewed current pharmacological and non-pharmacological interventions. A structured search was conducted on the PubMed database using the keywords Central Sensitization, Fibromyalgia, Complex Regional Pain Syndrome, and Neuropathic Pain, combined with the keywords Vision, Audition, Olfaction, Touch, Taste, and Proprioception. Papers were then filtered to discuss current treatment approaches. Articles within the last five years, from 2018 to 2023, have been included. Papers were excluded if they were animal studies; investigated tissue damage, disease processes, or addiction; or were conference proceedings or non-English. Results were summarized in table form to allow synthesis of evidence. As this study is a systematic review of previously published research rather than a clinical trial or experimental investigation, the risk of bias was assessed independently by at least two reviewers. 138 studies were identified and analyzed. Of these, 96 focused primarily on treatment options for chronic pain and were analyzed for this systematic review. There were a few emerging themes. No one therapy is effective, so a multidisciplinary approach to diagnosis, including pharmacological, somatic, and psychological treatment, is generally predicted to achieve the best outcomes. Cranial neurovascular compromise, especially of the trigeminal, glossopharyngeal, and potentially the vestibulocochlear nerve, is being increasingly revealed with the advancement of neuroimaging. Cortical and deep brain stimulation to evoke neuroplasticity is an emerging and promising therapy and warrants further investigation. Finally, including patients in their treatment plan allows them control and offers the ability to self-manage their pain. Risk of bias limits the ability to judge the quality of evidence. Full article

Insects acting as agricultural pests or disease vectors represent some of the greatest challenges to global health, food security and economics. Diverse technologies to combat insects of economic and medical importance have been and are continually being developed. These include natural and synthetic chemical insecticides and repellents, mass-trapping approaches and, more recently, an increasingly wide range of biological as well as genetic manipulations of insect vectors/pests. The increase in biological resistance and cross-resistance to many insecticides and repellents, the rapid expansion of human populations, as well as escalating climate change have extended or shifted the active periods and habitats of many insect species, creating new hurdles for attempts to defend humans from insects. At the same time, environmental, ecological and socio-political concerns continue to impact the utility of both current interventions as well as newly emerging innovative strategies. The near exponential increase in insect-based threats highlights the importance of basic and translational studies to design and develop novel technologies to combat detrimental insect populations. This review outlines the history of these challenges and describes the evolution of chemical insect control technologies, while highlighting existing and contemporary approaches to develop and deploy chemical repellents to address this threat to human health and agriculture. Full article

The use of acoustic communication and the relatively small antennae possessed by cicadas has led to the suggestion that antennal functions, specifically olfaction, are poorly developed in cicadas. The first step in determining antennal functions is to investigate the fine antennal structure. Scanning electron microscopy was used to visualize the morphology of the antennal sensilla in a diverse group of North American cicadas. The sensilla types and their distribution on the antennae of 30 species representing 12 genera, 6 tribes, and 3 subfamilies of North American cicadas are described and/or illustrated. Seven main classes and several subclasses of antennal sensilla were found: sensilla trichodea, sensilla chaetica, sensilla coeloconica, sensilla styloconica, foramina olfactoria, sensilla campaniformia, and sensilla cavitata-peg. Unique sensilla types and/or organizations of sensilla were found in many of the genera and differences between species of some genera were also present. No sexual dimorphism within species was found in the types or organizational patterns of the sensilla. The diversity of sensilla provides additional data for taxonomy and phylogenetic analyses. The potential function of the various sensilla types is hypothesized. Although relatively small, the antennae of cicadas are likely to provide significant information about their environment and increase their survival, including the selection of specific host plants and microhabitat selection observed in many species. Full article

Complete or partial loss of smell (anosmia), sometimes in association with distorted olfactory perceptions (parosmia), is a common neurological symptom affecting nearly 60% of patients suffering from post-acute neurological sequelae of COronaVIrus Disease of 2019 (COVID-19) syndrome, called long COVID. Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) may gain access from the nasal cavity to the brain (neurotropism), and the olfactory route has been proposed as a peripheral site of virus entry. COVID-19 is a risk factor for developing Alzheimer’s Disease (AD), an age-dependent and progressive neurodegenerative disorder characterized in affected patients by early olfaction dysfunction that precedes signs of cognitive decline associated with neurodegeneration in vulnerable brain regions of their limbic system. Here, we summarize the recent literature data supporting the causal correlation between the persistent olfactory deterioration following SARS-CoV-2 infection and the long-delayed manifestation of AD-like memory impairment. SARS-CoV-2 infection of the olfactory neuroepithelium is likely to trigger a pattern of detrimental events that, directly and/or indirectly, affect the anatomically interconnected hippocampal and cortical areas, thus resulting in tardive clinical dementia. We also delineate future advancement on pharmacological and rehabilitative treatments to improve the olfactory dysfunction in patients recovering even from the acute/mild phase of COVID-19. Collectively, the present review aims at highlighting the physiopathological nexus between COVID-19 anosmia and post-pandemic mental health to favor the development of best-targeted and more effective therapeutic strategies in the fight against the long-term neurological complications associated with SARS-CoV-2 infection. Full article

Olfaction is essential for key insect behaviors, such as host-seeking and mating, and is initiated by odorant-binding proteins (OBPs), which bind and transport hydrophobic odors. Thrips hawaiiensis is a major pest that infests the flowers of numerous horticultural crops, yet its chemosensory mechanisms remain poorly understood. Now, the availability of its genome assembly allows us to address this gap. To this end, we performed a comprehensive exploration and comparative analysis of its OBP genes. Our genome-wide analysis identified a total of 12 OBP genes in T. hawaiiensis, whereas the repertoire across other published thrips genomes ranges from 10 to 17, a count significantly lower than that in most other insects. Notably, transcriptomic and RT-qPCR analyses revealed consistent male-biased expression of OBPs in T. hawaiiensis, supporting their role in mate-finding and foraging behaviors. Furthermore, we identified 11 chemosensory proteins (CSPs). Transcriptomic and RT-qPCR analyses revealed that these CSPs exhibit an expression pattern similar to that of the OBPs, with over half of the genes showing significantly higher expression in males. This work provides a foundational framework for future functional studies of olfactory proteins, both in T. hawaiiensis and the wider insect community. Full article

Post-traumatic olfactory dysfunction (PTOD) is a common and often persistent sequela of mild traumatic brain injury (mTBI), with limited evidence-based treatment options. We propose that high-frequency rTMS applied to the left dorsolateral prefrontal cortex (DLPFC) may support olfactory recovery via top-down modulation of distributed olfactory, attentional, and reward networks, and we outline key mechanistic and methodological considerations for future studies. We summarize the case of a 70-year-old woman with severe post-traumatic hyposmia persisting for ~5 months, who underwent a 12-week, 10 Hz rTMS course over left DLPFC (36 sessions; 800 pulses/session). Using a structured door diary and repeated ratings across odour categories, she reported stepwise improvement starting around sessions 10–12 (re-emergence of pungent odours) and progressing to broad restoration, including subtle fragrances, by treatment end; no adverse events occurred. While causality cannot be inferred from a single case, this pattern is consistent with a network-level neuromodulatory effect and motivates controlled trials combining standardized olfactory testing with neurophysiology and neuroimaging. Full article

The house cricket, Acheta domesticus, is found globally. It is an agricultural pest causing economic damage to a wide variety of crops including cereal seedlings, vegetable crops, fruit plants, and stored grains. Additionally, crickets act as mechanical vectors of pathogens by harboring bacteria, fungi, viruses, and toxins, causing foodborne illnesses. They can contaminate stored grains, packaged foods, or animal feed due to deposition of their feces, lowering the quality of the food and creating food safety risks. Synthetic insect repellents, such as pyrethroids and carbamates, have been used previously in integrated pest management practices to control crickets. Though successful as repellents, they have been associated with health and environmental risks and concerns. The use of organic green repellents, such as plant essential oils, may be a viable alternative in pest management practices. In this study, we tested the effects of 27 plant-based essential oils on the behavior of A. domesticus. A. domesticus were introduced into an open arena to allow them unrestricted movement. A transparent plastic bottle containing an essential oil treatment was placed in the arena to allow voluntary entry by the crickets. Following a predetermined observation period, the number of crickets that entered the bottle was recorded, and percent entry was calculated as the proportion of individuals inside the bottle relative to the total number in the arena. Analysis of the percentage entry into the bottles allowed for a comparative assessment of repellency of the selected essential oils examined in this study. Essential oils that elicited high levels of entry into the bottle were categorized as having weak or no repellency, while those that demonstrated reduced entry were classified as moderate or strong repellents. Our results indicated that A. domesticus responded with strong repellent behavior to nearly half of the essential oils tested, while four essential oils and two synthetic repellents evoked no significant repellent responses. Four strong repellent essential oils, namely peppermint, rosemary, cinnamon, and lemongrass, were tested at different concentrations and showed a clear dose-dependent repellent effect. The results suggest that selected essential oils can be useful in the development of more natural “green” insect repellents. Full article