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Journal of Comparative Physiology. A,... Jul 2023Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to... (Review)
Review
Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to navigate toward odor sources-such as integrating flow information with odor information, comparing odor concentration across sensors, and integrating odor information over time. Because arthropods share many homologous brain structures-antennal lobes for processing olfactory information, mechanosensors for processing flow, mushroom bodies (or hemi-ellipsoid bodies) for associative learning, and central complexes for navigation, it is likely that these closely related behaviors are mediated by conserved neural circuits. However, differences in the types of odors they seek, the physics of odor dispersal, and the physics of locomotion in water, air, and on substrates mean that these circuits must have adapted to generate a wide diversity of odor-seeking behaviors. In this review, we discuss common strategies and specializations observed in olfactory navigation behavior across arthropods, and review our current knowledge about the neural circuits subserving this behavior. We propose that a comparative study of arthropod nervous systems may provide insight into how a set of basic circuit structures has diversified to generate behavior adapted to different environments.
Topics: Animals; Arthropods; Olfactory Pathways; Smell; Odorants; Brain
PubMed: 36658447
DOI: 10.1007/s00359-022-01611-9 -
Current Allergy and Asthma Reports Mar 2023Olfactory dysfunction contributes to the psychopathology of mental illness. In this review, we describe the neurobiology of olfaction, and the most common olfactory... (Review)
Review
PURPOSE OF REVIEW
Olfactory dysfunction contributes to the psychopathology of mental illness. In this review, we describe the neurobiology of olfaction, and the most common olfactory alterations in several mental illnesses. We also highlight the role, hitherto underestimated, that the olfactory pathways play in the regulation of higher brain functions and its involvement in the pathophysiology of psychiatric disorders, as well as the effect of inflammation on neurogenesis as a possible mechanism involved in olfactory dysfunction in psychiatric conditions.
RECENT FINDINGS
The olfactory deficits present in anxiety, depression, schizophrenia or bipolar disorder consist of specific alterations of different components of the sense of smell, mainly the identification of odours, as well as the qualifications of their hedonic valence (pleasant or unpleasant). Epidemiological findings have shown that both environmental factors, such as air pollutants, and inflammatory disease of the upper respiratory tract, can contribute to an increased risk of mental illness, at least in part, due to peripheral inflammatory mechanisms of the olfactory system. In this review, we describe the neurobiology of olfaction, and the most common olfactory function alterations in several psychiatric conditions and its role as a useful symptom for the differential diagnosis. We also highlight the effect of inflammation on neurogenesis as a possible mechanism involved in olfactory dysfunction in these psychiatric conditions.
Topics: Humans; Smell; Mental Disorders; Olfaction Disorders; Emotions; Inflammation
PubMed: 36696016
DOI: 10.1007/s11882-023-01068-z -
Biological Reviews of the Cambridge... Feb 2022Odorant-binding proteins (OBPs) of vertebrates belong to the lipocalin superfamily and perform a dual function: solubilizing and ferrying volatile pheromones to the... (Review)
Review
Odorant-binding proteins (OBPs) of vertebrates belong to the lipocalin superfamily and perform a dual function: solubilizing and ferrying volatile pheromones to the olfactory receptors, and complexing the same molecules in specialized glands and assisting their release into the environment. Within vertebrates, to date they have been reported only in mammals, apart from two studies on amphibians. Based on the small number of OBPs expressed in each species, on their sites of production outside the olfactory area and their presence in biological fluids known to be pheromone carriers, such as urine, saliva and sexual secretions, we conclude that OBPs of mammals are specifically dedicated to pheromonal communication. This assumption is further supported by the observation that some OBPs present in biological secretions are endowed with their own pheromonal activity, adding renewed interest to these proteins. Another novel piece of evidence is the recent discovery that glycosylation and phosphorylation can modulate the binding activity of these proteins, improving their affinity to pheromones and narrowing their specificity. A comparison with insects and other arthropods shows a completely different scenario. While mammalian OBPs are specifically tuned to pheromones, those of insects, which are completely different in sequence and structure, include carriers for general odorants in addition to those dedicated to pheromones. Additionally, whereas mammals adopted a single family of carrier proteins for chemical communication, insects and other arthropods are endowed with several families of semiochemical-binding proteins. Here, we review the literature on the structural and functional properties of vertebrate OBPs, summarize the most interesting new findings and suggest possible exciting future developments.
Topics: Animals; Insect Proteins; Insecta; Mammals; Odorants; Receptors, Odorant; Smell
PubMed: 34480392
DOI: 10.1111/brv.12787 -
Annual Review of Entomology Jan 2022In this review, we highlight sources of alcohols in nature, as well as the behavioral and ecological roles that these fermentation cues play in the short lifespan of .... (Review)
Review
In this review, we highlight sources of alcohols in nature, as well as the behavioral and ecological roles that these fermentation cues play in the short lifespan of . With a focus on neuroethology, we describe the olfactory detection of alcohol as well as ensuing neural signaling within the brain of the fly. We proceed to explain the plethora of behaviors related to alcohol, including attraction, feeding, and oviposition, as well as general effects on aggression and courtship. All of these behaviors are shaped by physiological state and social contexts. In a comparative perspective, we also discuss inter- and intraspecies differences related to alcohol tolerance and metabolism. Lastly, we provide corollaries with other dipteran and coleopteran insect species that also have olfactory systems attuned to ethanol detection and describe ecological and evolutionary directions for further studies of the natural history of alcohol and the fly.
Topics: Animals; Biological Evolution; Drosophila; Drosophila melanogaster; Female; Nervous System; Smell
PubMed: 34995092
DOI: 10.1146/annurev-ento-070721-091828 -
Chemical Senses Jan 2021Approximately 5% of the general population is affected by functional anosmia with approximately additional 15% exhibiting decreased olfactory function. Many of these... (Review)
Review
Approximately 5% of the general population is affected by functional anosmia with approximately additional 15% exhibiting decreased olfactory function. Many of these individuals ask for help. Because the subjective rating of olfactory function is biased, assessment of olfactory function is important. Olfactory measurements are needed for patient counseling and the tracking of changes in the sense of smell over time. The present review provides an overview of frequently used psychophysical tests for olfactory function, discusses differences between threshold and suprathreshold aspects of olfactory function, and gives examples on how to apply psychophysical tests.
Topics: Humans; Olfaction Disorders; Smell
PubMed: 34942008
DOI: 10.1093/chemse/bjab053 -
Neuropathology and Applied Neurobiology Apr 2024Olfactory dysfunction is one of the most common symptoms of COVID-19. In the first 2 years of the pandemic, it was frequently reported, although its incidence has... (Review)
Review
Olfactory dysfunction is one of the most common symptoms of COVID-19. In the first 2 years of the pandemic, it was frequently reported, although its incidence has significantly decreased with the emergence of the Omicron variant, which has since become the dominant viral strain. Nevertheless, many patients continue to suffer from persistent dysosmia and dysgeusia, making COVID-19-associated olfactory dysfunction an ongoing health concern. The proposed pathogenic mechanisms of COVID-19-associated olfactory dysfunction are complex and likely multifactorial. While evidence suggests that infection of sustentacular cells and associated mucosal inflammation may be the culprit of acute, transient smell loss, alterations in other components of the olfactory system (e.g., olfactory receptor neuron dysfunction, olfactory bulb injury and alterations in the olfactory cortex) may lead to persistent, long-term olfactory dysfunction. This review aims to provide a comprehensive summary of the epidemiology, clinical manifestations and current understanding of the pathogenic mechanisms of COVID-19-associated olfactory dysfunction.
Topics: Humans; COVID-19; SARS-CoV-2; Smell; Olfaction Disorders
PubMed: 38419211
DOI: 10.1111/nan.12960 -
Cell and Tissue Research Jan 2022The olfactory system allows animals to navigate in their environment to feed, mate, and escape predators. It is well established that odorant exposure or electrical... (Review)
Review
The olfactory system allows animals to navigate in their environment to feed, mate, and escape predators. It is well established that odorant exposure or electrical stimulation of the olfactory system induces stereotyped motor responses in fishes. However, the neural circuitry responsible for the olfactomotor transformations is only beginning to be unraveled. A neural substrate eliciting motor responses to olfactory inputs was identified in the lamprey, a basal vertebrate used extensively to examine the neural mechanisms underlying sensorimotor transformations. Two pathways were discovered from the olfactory organ in the periphery to the brainstem motor nuclei responsible for controlling swimming. The first pathway originates from sensory neurons located in the accessory olfactory organ and reaches a single population of projection neurons in the medial olfactory bulb, which, in turn, transmit the olfactory signals to the posterior tuberculum and then to downstream brainstem locomotor centers. A second pathway originates from the main olfactory epithelium and reaches the main olfactory bulb, the neurons of which project to the pallium/cortex. The olfactory signals are then conveyed to the posterior tuberculum and then to brainstem locomotor centers. Olfactomotor behavior can adapt, and studies were aimed at defining the underlying neural mechanisms. Modulation of bulbar neural activity by GABAergic, dopaminergic, and serotoninergic inputs is likely to provide strong control over the hardwired circuits to produce appropriate motor behavior in response to olfactory cues. This review summarizes current knowledge relative to the neural circuitry producing olfactomotor behavior in lampreys and their modulatory mechanisms.
Topics: Animals; Lampreys; Locomotion; Smell
PubMed: 34674044
DOI: 10.1007/s00441-021-03536-2 -
Cell and Tissue Research Jan 2021Amniotes originated on land, but aquatic/amphibious groups emerged multiple times independently in amniotes. On becoming aquatic, species with different phylogenetic... (Review)
Review
Amniotes originated on land, but aquatic/amphibious groups emerged multiple times independently in amniotes. On becoming aquatic, species with different phylogenetic backgrounds and body plans have to adapt themselves to handle similar problems inflicted by their new environment, and this makes aquatic adaptation of amniotes one of the greatest natural experiments. Particularly, evolution of the sense of smell upon aquatic adaptation is of great interest because receptors required for underwater olfaction differ remarkably from those for terrestrial olfaction. Here, I review the olfactory capabilities of aquatic/amphibious amniotes, especially those of cetaceans and sea snakes. Most aquatic/amphibious amniotes show reduced olfactory organs, receptor gene repertoires, and olfactory capabilities. Remarkably, cetaceans and sea snakes show extreme examples: cetaceans have lost the vomeronasal system, and furthermore, toothed whales have lost all of their olfactory nervous systems. Baleen whales can smell in the air, but their olfactory capability is limited. Fully aquatic sea snakes have lost the main olfactory system but they retain the vomeronasal system for sensing underwater. Amphibious species show an intermediate status between terrestrial and aquatic species, implying their importance on understanding the process of aquatic adaptation. The olfactory capabilities of aquatic amniotes are diverse, reflecting their diverse phylogenetic backgrounds and ecology.
Topics: Animals; Fishes; Smell
PubMed: 33409651
DOI: 10.1007/s00441-020-03382-8 -
International Forum of Allergy &... Nov 2020
Topics: Humans; Odorants; Olfaction Disorders; Olfactory Bulb; Smell
PubMed: 32776673
DOI: 10.1002/alr.22681 -
Trends in Genetics : TIG Feb 2023Gene-editing technologies have revolutionized the field of mosquito sensory biology. These technologies have been used to knock in reporter genes in-frame with neuronal... (Review)
Review
Gene-editing technologies have revolutionized the field of mosquito sensory biology. These technologies have been used to knock in reporter genes in-frame with neuronal genes and tag specific mosquito neurons to detect their activities using binary expression systems. Despite these advances, novel tools still need to be developed to elucidate the transmission of olfactory signals from the periphery to the brain. Here, we propose the development of a set of tools, including novel driver lines as well as sensors of neuromodulatory activities, which can advance our knowledge of how sensory input triggers behavioral outputs. This information can change our understanding of mosquito neurobiology and lead to the development of strategies for mosquito behavioral manipulation to reduce bites and disease transmission.
Topics: Animals; Culicidae; Smell; Gene Editing; Neurons
PubMed: 36414481
DOI: 10.1016/j.tig.2022.10.007