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Integrative and Comparative Biology Aug 2023Pheromones are chemical signals that facilitate communication between animals, and most animals use pheromones for reproduction and other forms of social behavior. The... (Review)
Review
Pheromones are chemical signals that facilitate communication between animals, and most animals use pheromones for reproduction and other forms of social behavior. The identification of key ligands and olfactory receptors used for pheromonal communication provides insight into the sensory processing of these important cues. An individual's responses to pheromones can be plastic, as physiological status modulates behavioral outputs. In this review, we outline the mechanisms for pheromone sensation and highlight physiological mechanisms that modify pheromone-guided behavior. We focus on hormones, which regulate pheromonal communication across vertebrates including fish, amphibians, and rodents. This regulation may occur in peripheral olfactory organs and the brain, but the mechanisms remain unclear. While this review centers on research in fish, we will discuss other systems to provide insight into how hormonal mechanisms function across taxa.
Topics: Animals; Pheromones; Smell; Hormones; Fishes; Perception
PubMed: 37263784
DOI: 10.1093/icb/icad049 -
Frontiers in Behavioral Neuroscience 2023Olfaction is a critical sense that allows animals to navigate and understand their environment. In mammals, the critical brain structure to receive and process olfactory... (Review)
Review
Olfaction is a critical sense that allows animals to navigate and understand their environment. In mammals, the critical brain structure to receive and process olfactory information is the olfactory bulb, a structure characterized by a laminated pattern with different types of neurons, some of which project to distant telencephalic structures, like the piriform cortex, the amygdala, and the hippocampal formation. Therefore, the olfactory bulb is the first structure of a complex cognitive network that relates olfaction to different types of memory, including episodic memories. The olfactory bulb continuously adds inhibitory newborn neurons throughout life; these cells locate both in the granule and glomerular layers and integrate into the olfactory circuits, inhibiting projection neurons. However, the roles of these cells modulating olfactory memories are unclear, particularly their role in fear memories. We consider that olfactory neurogenesis might modulate olfactory fear memories by a plastic process occurring in the olfactory bulb.
PubMed: 37840547
DOI: 10.3389/fnbeh.2023.1278324 -
Proceedings of the National Academy of... Aug 2023Long-range olfactory search is an extremely difficult task in view of the sparsity of odor signals that are available to the searcher and the complex encoding of the...
Long-range olfactory search is an extremely difficult task in view of the sparsity of odor signals that are available to the searcher and the complex encoding of the information about the source location. Current algorithmic approaches typically require a continuous memory space, sometimes of large dimensionality, which may hamper their optimization and often obscure their interpretation. Here, we show how finite-state controllers with a small set of discrete memory states are expressive enough to display rich, time-extended behavioral modules that resemble the ones observed in living organisms. Finite-state controllers optimized for olfactory search have an immediate interpretation in terms of approximate clocks and coarse-grained spatial maps, suggesting connections with neural models of search behavior.
Topics: Smell; Odorants
PubMed: 37579168
DOI: 10.1073/pnas.2304230120 -
Auris, Nasus, Larynx Aug 2023One of the unique symptoms of COVID-19 is chemosensory dysfunction. Almost three years since the beginning of the pandemic of COVID-19, there have been many studies on... (Review)
Review
One of the unique symptoms of COVID-19 is chemosensory dysfunction. Almost three years since the beginning of the pandemic of COVID-19, there have been many studies on the symptoms, progress, and possible causes, and also studies on methods that may facilitate recovery of the senses. Studies have shown that some people recover their senses even within a couple of weeks whereas there are other patients that fail to recover chemosensory functions fully for several months and some never fully recover. Here we summarize the symptoms and the progress, and then review the papers on the causation as well as the treatments that may help facilitate the recovery of the symptoms. Depending on the differences in the levels of severity and the locations where the main pathological venues are, what is most effective in facilitating recovery can vary largely across patients and thus may require individualized strategies for each patient. The goal of this paper is to provide some thoughts on these choices depending on the differences in the causes and severity.
Topics: Humans; COVID-19; SARS-CoV-2; Olfaction Disorders; Smell; Pandemics
PubMed: 36529610
DOI: 10.1016/j.anl.2022.12.002 -
Ear, Nose, & Throat Journal May 2024The pandemic has affected over 182 million coronavirus disease 2019 (COVID-19) cases worldwide. Accumulated evidence indicates that anosmia is one of the significant... (Review)
Review
OBJECTIVES
The pandemic has affected over 182 million coronavirus disease 2019 (COVID-19) cases worldwide. Accumulated evidence indicates that anosmia is one of the significant characteristics of COVID-19 with a high prevalence. However, many aspects of COVID-19-induced anosmia are still far from being fully understood. The purpose of this review is to summarize recent developments in COVID-19-induced anosmia to increase awareness of the condition.
METHODS
A literature search was carried out using the PubMed, Embase, Web of Science, and Scopus. We reviewed the latest literature on COVID-19-induced anosmia, including mechanisms of pathogenesis, olfactory testing, anosmia as predictive tool, pathological examinations, imaging findings, affected factors, co-existing diseases, treatments, prognosis, hypothesis theories, and future directions.
RESULTS
The possible pathogenesis of COVID-19-induced anosmia may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The D614G spike variant may also play a role in the increased number of anosmia patients. Anosmia may also be an essential indicator of COVID-19 spread and an early indicator of the effectiveness of political decisions. The occurrence and development of COVID-19-induced anosmia may be influenced by smoking behaviors and underlying diseases such as type 2 diabetes, gastroesophageal disorders, and rhinitis. Most patients with COVID-19-induced anosmia can fully or partially recover their olfactory function for varying durations. COVID-19-induced anosmia can be treated with various approaches such as glucocorticoids and olfactory training.
CONCLUSION
Anosmia is one of the main features of COVID-19 and the underlying disease of the patient may also influence its occurrence and development. The possible pathogenesis of COVID-19-induced anosmia is very complicated, which may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system.
Topics: COVID-19; Humans; Anosmia; SARS-CoV-2; Olfactory Mucosa; Olfaction Disorders
PubMed: 34587819
DOI: 10.1177/01455613211048998 -
Cell Reports Dec 2023Co-transmission of multiple neurotransmitters from a single neuron increases the complexity of signaling information within defined neuronal circuits. Superficial...
Co-transmission of multiple neurotransmitters from a single neuron increases the complexity of signaling information within defined neuronal circuits. Superficial short-axon cells in the olfactory bulb release both dopamine and γ-aminobutyric acid (GABA), yet the specific targets of these neurotransmitters and their respective roles in olfaction have remained unknown. Here, we implement intersectional genetics in mice to selectively block GABA or dopamine release from superficial short-axon cells to identify their distinct cellular targets, impact on circuit function, and behavioral contribution of each neurotransmitter toward olfactory behaviors. We provide functional and anatomical evidence for divergent superficial short-axon cell signaling onto downstream neurons to shape patterns of mitral cell firing that contribute to olfactory-related behaviors.
Topics: Mice; Animals; Olfactory Bulb; Smell; Dopamine; Interneurons; gamma-Aminobutyric Acid; Neurotransmitter Agents
PubMed: 37980561
DOI: 10.1016/j.celrep.2023.113471 -
Strahlentherapie Und Onkologie : Organ... Oct 2023Patients sometimes report phosphene and phantosmia during radiation therapy (RT). However, the detail features and related factors are not well understood. Our...
PURPOSE
Patients sometimes report phosphene and phantosmia during radiation therapy (RT). However, the detail features and related factors are not well understood. Our prospective study aimed to investigate the characteristics of phantosmias and phosphenes, to identify factors that influence the occurrence, intensity and hedonic (pleasantness/unpleasantness) ratings of such sensations during RT.
METHODS
We included a total of 106 patients (37 women), who underwent RT in regions of the brain, ear, nose, throat (ENT), and other areas of the body for a duration of 43 ± 5 days. Medical history and treatment parameters were collected in a structured medical interview. Olfactory function was measured using the Sniffin' Stick Odor Identification Test at baseline. Phantosmia and phosphene were recorded weekly based on a self-report questionnaire.
RESULTS
There were 37% of the patients experiencing phantosmias, 51% experiencing phosphenes, and 29% simultaneously experiencing both sensations. Phosphenes were typically perceived as a flashily blue, white and/or purple light, phantosmias were typically perceived as a chemical-like, metallic or burnt smell. Younger age (F = 7.81, p < 0.01), radiation in the brain region (χ = 14.05, p = 0.02), absence of taste problems (χ = 10.28, p = 0.01), and proton RT (χ = 10.57, p = 0.01) were related to these abnormal sensations. History of chemical/dust exposure predicted lower intensity (B = -1.52, p = 0.02) and lower unpleasantness (B = 0.49, p = 0.03) of phantosmia. In contrast, disease (tumor) duration (B = 0.11, p < 0.01), food allergy (B = 2.77, p < 0.01), and epilepsy (B = -1.50, p = 0.02) influence phosphenes intensity. Analgesics intake predicted a higher pleasantness of the phosphenes (B = 0.47, p < 0.01).
CONCLUSIONS
Phantosmias and phosphenes are common during RT. The treatment settings and individual arousal level influence the occurrence, intensity and hedonic of such abnormal sensations. Phantosmias and phosphenes may involve more central neural than peripheral mechanism, and they could be elicited with activation of areas that are not regarded to be part of the olfactory or visual network.
Topics: Humans; Female; Smell; Prospective Studies; Olfaction Disorders; Phosphenes; Emotions
PubMed: 37270715
DOI: 10.1007/s00066-023-02095-5 -
Behavioral and Brain Functions : BBF Dec 2023Parosmia is a qualitative olfactory dysfunction presenting as "distorted odor perception" in presence of an odor source. Aim of this study was to use resting state...
OBJECTIVE
Parosmia is a qualitative olfactory dysfunction presenting as "distorted odor perception" in presence of an odor source. Aim of this study was to use resting state functional connectivity to gain more information on the alteration of olfactory processing at the level of the central nervous system level.
METHODS
A cross sectional study was performed in 145 patients with parosmia (age range 20-76 years; 90 women). Presence and degree of parosmia was diagnosed on the basis of standardized questionnaires. Participants also received olfactory testing using the "Sniffin' Sticks". Then they underwent resting state scans using a 3 T magnetic resonance imaging scanner while fixating on a cross.
RESULTS
Whole brain analyses revealed reduced functional connectivity in salience as well as executive control networks. Region of interest-based analyses also supported reduced functional connectivity measures between primary and secondary olfactory eloquent areas (temporal pole, supramarginal gyrus and right orbitofrontal cortex; dorso-lateral pre-frontal cortex and the right piriform cortex).
CONCLUSIONS
Participants with parosmia exhibited a reduced information flow between memory, decision making centers, and primary and secondary olfactory areas.
Topics: Humans; Female; Young Adult; Adult; Middle Aged; Aged; Cross-Sectional Studies; Olfaction Disorders; Smell; Brain; Magnetic Resonance Imaging
PubMed: 38115149
DOI: 10.1186/s12993-023-00225-8 -
Annals of Epidemiology Sep 2023To complement conventional testing methods for severe acute respiratory syndrome coronavirus type 2 infections, dogs' olfactory capability for true real-time detection... (Review)
Review
PURPOSE
To complement conventional testing methods for severe acute respiratory syndrome coronavirus type 2 infections, dogs' olfactory capability for true real-time detection has been investigated worldwide. Diseases produce specific scents in affected individuals via volatile organic compounds. This systematic review evaluates the current evidence for canine olfaction as a reliable coronavirus disease 2019 screening tool.
METHODS
Two independent study quality assessment tools were used: the QUADAS-2 tool for the evaluation of laboratory tests' diagnostic accuracy, designed for systematic reviews, and a general evaluation tool for canine detection studies, adapted to medical detection. Various study design, sample, dog, and olfactory training features were considered as potential confounding factors.
RESULTS
Twenty-seven studies from 15 countries were evaluated. Respectively, four and six studies had a low risk of bias and high quality: the four QUADAS-2 nonbiased studies resulted in ranges of 81%-97% sensitivity and 91%-100% specificity. The six high-quality studies, according to the general evaluation system, revealed ranges of 82%-97% sensitivity and 83%-100% specificity. The other studies contained high bias risks and applicability and/or quality concerns.
CONCLUSIONS
Standardization and certification procedures as used for canine explosives detection are needed for medical detection dogs for the optimal and structured usage of their undoubtful potential.
Topics: Animals; Dogs; Humans; COVID-19; SARS-CoV-2; Sensitivity and Specificity; Smell; Systematic Reviews as Topic
PubMed: 37209927
DOI: 10.1016/j.annepidem.2023.05.002 -
Progress in Neurobiology Sep 2023Olfaction is an important sensory modality for many species and greatly influences animal and human behavior. Still, much about olfactory perception remains unknown. The... (Review)
Review
Olfaction is an important sensory modality for many species and greatly influences animal and human behavior. Still, much about olfactory perception remains unknown. The anterior olfactory nucleus is one of the brain's central early olfactory processing areas. Located directly posterior to the olfactory bulb in the olfactory peduncle with extensive in- and output connections and unique cellular composition, it connects olfactory processing centers of the left and right hemispheres. Almost 20 years have passed since the last comprehensive review on the anterior olfactory nucleus has been published and significant advances regarding its anatomy, function, and pathophysiology have been made in the meantime. Here we briefly summarize previous knowledge on the anterior olfactory nucleus, give detailed insights into the progress that has been made in recent years, and map out its emerging importance in translational research of neurological diseases.
Topics: Animals; Humans; Olfactory Pathways; Olfactory Bulb; Smell; Olfactory Cortex
PubMed: 37343762
DOI: 10.1016/j.pneurobio.2023.102486