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Cold Spring Harbor Protocols Oct 2023Female mosquitoes respond to the world around them by using chemosensory organs, such as their antennae, to detect volatile compounds emitted from a vertebrate host....
Female mosquitoes respond to the world around them by using chemosensory organs, such as their antennae, to detect volatile compounds emitted from a vertebrate host. These chemosensory systems facilitate the interpretation of external stimuli from the periphery by connecting to the central nervous system and eliciting behaviors necessary for survival, such as obtaining a blood meal. This innate behavior leads to the transmission of pathogens, including dengue virus, chikungunya virus, and Zika virus. Olfaction is a primary sense mosquitoes use to differentiate between vertebrate hosts, and studying it can lead to novel strategies to reduce the risk of disease. In this protocol, we present an olfactory-driven behavioral assay using a uniport olfactometer that measures mosquito attraction rate to a specific stimulus. We include details of the behavioral assay and data analysis as well as how to prepare the mosquitoes before their introduction into the olfactometer. This uniport olfactometer behavioral assay is currently one of the most reliable methods to study mosquito attraction to a single stimulus.
Topics: Animals; Female; Humans; Culicidae; Zika Virus; Smell; Zika Virus Infection
PubMed: 37019611
DOI: 10.1101/pdb.prot108175 -
ELife Sep 2023How memories are used by the brain to guide future action is poorly understood. In olfactory associative learning in , multiple compartments of the mushroom body act in...
How memories are used by the brain to guide future action is poorly understood. In olfactory associative learning in , multiple compartments of the mushroom body act in parallel to assign a valence to a stimulus. Here, we show that appetitive memories stored in different compartments induce different levels of upwind locomotion. Using a photoactivation screen of a new collection of split-GAL4 drivers and EM connectomics, we identified a cluster of neurons postsynaptic to the mushroom body output neurons (MBONs) that can trigger robust upwind steering. These UpWind Neurons (UpWiNs) integrate inhibitory and excitatory synaptic inputs from MBONs of appetitive and aversive memory compartments, respectively. After formation of appetitive memory, UpWiNs acquire enhanced response to reward-predicting odors as the response of the inhibitory presynaptic MBON undergoes depression. Blocking UpWiNs impaired appetitive memory and reduced upwind locomotion during retrieval. Photoactivation of UpWiNs also increased the chance of returning to a location where activation was terminated, suggesting an additional role in olfactory navigation. Thus, our results provide insight into how learned abstract valences are gradually transformed into concrete memory-driven actions through divergent and convergent networks, a neuronal architecture that is commonly found in the vertebrate and invertebrate brains.
Topics: Animals; Wind; Learning; Drosophila; Smell; Neurons; Mushroom Bodies; Drosophila melanogaster
PubMed: 37721371
DOI: 10.7554/eLife.85756 -
Nederlands Tijdschrift Voor Geneeskunde Nov 2023Olfactory disorders are common and have consequences for the quality of life of patients. The main causes are post viral upper respiratory tract infections, head trauma...
Olfactory disorders are common and have consequences for the quality of life of patients. The main causes are post viral upper respiratory tract infections, head trauma and sinonasal disease. However, there are many more less frequent causes which we illustrate by showing three different rare cases. A distinguishment between qualitative and quantitative olfactory disorders is made which is mainly based on the patient's history and olfactory testing. It is important to diagnose the cause of an olfactory disorder because treatment options are dependent on it and it can be a symptom of a progressive disease. Olfactory training is a proven treatment for many perceptive olfactory disorders and is easily performed by most patients.
Topics: Humans; Quality of Life; Olfaction Disorders; Smell
PubMed: 37994709
DOI: No ID Found -
International Journal of Molecular... Mar 2024There is very little knowledge regarding the terminal nerve, from its implications in the involvement and pathogenesis of certain conditions, to its embryological... (Review)
Review
There is very little knowledge regarding the terminal nerve, from its implications in the involvement and pathogenesis of certain conditions, to its embryological origin. With this review, we try to summarize the most important evidence on the terminal nerve, aiming to clarify its anatomy and the various functions attributed to it, to better interpret its potential involvement in pathological processes. Recent studies have also suggested its potential role in the control of human reproductive functions and behaviors. It has been hypothesized that it plays a role in the unconscious perception of specific odors that influence autonomic and reproductive hormonal systems through the hypothalamic-pituitary-gonadal axis. We used the PubMed database and found different articles which were then selected independently by three authors. We found 166 articles, of which, after careful selection, only 21 were analyzed. The terminal nerve was always thought to be unimportant in our body. It was well studied in different types of animals, but few studies have been completed in humans. For this reason, its function remains unknown. Studies suggest a possible implication in olfaction due to the anatomical proximity with the olfactive nerve. Others suggest a more important role in reproduction and sexual behaviors. New emerging information suggests a possible role in Kallmann syndrome and COVID-19.
Topics: Animals; Humans; Smell; Kallmann Syndrome; Nerve Endings; Autonomic Nervous System; COVID-19
PubMed: 38612730
DOI: 10.3390/ijms25073920 -
Nature Neuroscience Dec 2023
Topics: Smell; Odorants
PubMed: 38040975
DOI: 10.1038/s41593-023-01525-y -
Science (New York, N.Y.) Dec 2023During aversive olfactory conditioning, aversive shock information needs to be transmitted to the mushroom bodies (MBs) to associate with odor information. We report...
During aversive olfactory conditioning, aversive shock information needs to be transmitted to the mushroom bodies (MBs) to associate with odor information. We report that aversive information is transmitted by ensheathing glia (EG) that surround the MBs. Shock induces vesicular exocytosis of glutamate from EG. Blocking exocytosis impairs aversive learning, whereas activation of EG can replace aversive stimuli during conditioning. Glutamate released from EG binds to -methyl-d-aspartate receptors in the MBs, but because of Mg block, Ca influx occurs only when flies are simultaneously exposed to an odor. Vesicular exocytosis from EG also induces shock-associated dopamine release, which plays a role in preventing formation of inappropriate associations. These results demonstrate that vesicular glutamate released from EG transmits negative valence information required for associative learning.
Topics: Animals; Avoidance Learning; Conditioning, Psychological; Drosophila melanogaster; Glutamates; Mushroom Bodies; Neuroglia; Odorants; Smell
PubMed: 38127757
DOI: 10.1126/science.adf7429 -
The Journals of Gerontology. Series A,... Jul 2023Olfactory impairment is increasingly recognized as a biomarker of frailty, but the relationship between olfactory subdomains that describe peripheral or central...
BACKGROUND
Olfactory impairment is increasingly recognized as a biomarker of frailty, but the relationship between olfactory subdomains that describe peripheral or central dysfunction and frailty remains unexplored.
METHODS
We examined 1 160 older adults from the National Social Life, Health, and Aging Project Wave 3. Olfactory identification (OI): the ability to identify an odorant; and olfactory sensitivity (OS): the ability to detect the presence of an odorant, were assessed using 5- and 6-point measures, respectively. Frailty was operationalized as both a 37-item frailty index (FI) and the 5-item Physical Frailty Phenotype (PFP). Mixed models were fit to examine the association between OI, OS, FI, and PFP, while adjusting for demographic and clinical covariates.
RESULTS
Participants in the most-frail PFP category had lower OI and OS scores (OI: 3.88 vs 4.19, p = .016; OS: 3.15 vs 3.47, p = .031), whereas participants in the most-frail FI category exhibited lower OI scores but not OS scores when compared to nonfrail participants (OI: 3.72 vs 4.27, p = .014; OS: 3.19 vs 3.43, p = .476). Adjusted mixed models showed that a point increase in OI was associated with a lower PFP score (β = -0.107, p = .006) and FI score (β = -0.009, p = .010). A point increase in OS was associated with a lower PFP score (β = -0.058, p = .016) but not FI score (β = -0.004, p = .064).
CONCLUSION
Both OS and OI, predominantly peripheral and central measures of olfaction, respectively, are associated with frailty implicating olfaction as a potential biomarker and risk factor for frailty.
Topics: Humans; Aged; Frailty; Smell; Risk Factors; Aging; Olfaction Disorders; Frail Elderly; Geriatric Assessment
PubMed: 36502375
DOI: 10.1093/gerona/glac237 -
Neurosciences (Riyadh, Saudi Arabia) Jan 2024Parkinson's disease (PD) is a complex neurodegenerative motor disorder caused by the loss of dopaminergic neurons in the substantia nigra pars compacta. The substantia... (Review)
Review
Parkinson's disease (PD) is a complex neurodegenerative motor disorder caused by the loss of dopaminergic neurons in the substantia nigra pars compacta. The substantia nigra is neither the first nor the only brain region affected by PD. Recent and old studies have shown that PD does not only affect the CNS; in fact, autonomic innervation in the GIT, skin, and olfactory system was found to be affected by α-synuclein pathology outside the CNS, affecting patients' quality of life. In the gastrointestinal system, dysphagia, constipation, and bacterial overgrowth in the small intestine are common in patients with PD. In addition, several skin conditions were reported in PD, including seborrheic dermatitis, rosacea, melanoma, and others. Finally, olfactory system dysfunction, such as reduced touch sensation and smell, was associated with motor abnormalities. Further high-quality studies are needed to develop reliable tests that could help in the early diagnosis of PD.
Topics: Humans; Parkinson Disease; Quality of Life; Smell; Skin Abnormalities
PubMed: 38195133
DOI: 10.17712/nsj.2024.1.20230062 -
Physiology & Behavior Oct 2023Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the... (Review)
Review
Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the axilla is an active, odor-producing region that mediates social communication via the sense of smell, this article focuses on the biological mechanisms underlying the creation of axillary odor, as well as the intrinsic and extrinsic factors likely to impact the odor and determine individual differences. The list of intrinsic factors discussed includes sex, age, ethnicity, emotions, and personality, and extrinsic factors include dietary choices, diseases, climate, and hygienic habits. In addition, we also draw attention to gaps in our understanding of each factor, including, for example, topical areas such as the effect of climate on body odor variation. Fundamental challenges and emerging research opportunities are further outlined in the discussion. Finally, we suggest guidelines and best practices based on the factors reviewed herein for preparatory protocols of sweat collection, data analysis, and interpretation.
Topics: Humans; Odorants; Sweat; Smell; Sweating; Axilla
PubMed: 37516230
DOI: 10.1016/j.physbeh.2023.114307 -
Rhinology Oct 2023
Topics: Humans; Smell; Taste; Odorants
PubMed: 37772643
DOI: 10.4193/Rhin23.905