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1.
PLoS One ; 19(7): e0306290, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38950019

RESUMO

BACKGROUND: More than a year after recovering from COVID-19, a large proportion of individuals, many of whom work in the healthcare sector, still report olfactory dysfunctions. However, olfactory dysfunction was common already before the COVID-19 pandemic, making it necessary to also consider the existing baseline prevalence of olfactory dysfunction. To establish the adjusted prevalence of COVID-19 related olfactory dysfunction, we assessed smell function in healthcare workers who had contracted COVID-19 during the first wave of the pandemic using psychophysical testing. METHODS: Participants were continuously tested for SARS-CoV-2 IgG antibodies since the beginning of the pandemic. To assess the baseline rate of olfactory dysfunction in the population and to control for the possibility of skewed recruitment of individuals with prior olfactory dysfunction, consistent SARS-CoV-2 IgG naïve individuals were tested as a control group. RESULTS: Fifteen months after contracting COVID-19, 37% of healthcare workers demonstrated a quantitative reduction in their sense of smell, compared to only 20% of the individuals in the control group. Fifty-one percent of COVID-19-recovered individuals reported qualitative symptoms, compared to only 5% in the control group. In a follow-up study 2.6 years after COVID-19 diagnosis, 24% of all tested recovered individuals still experienced parosmia. CONCLUSIONS: In summary, 65% of healthcare workers experienced parosmia/hyposmia 15 months after contracting COVID-19. When compared to a control group, the prevalence of olfactory dysfunction in the population increased by 41 percentage points. Parosmia symptoms were still lingering two-and-a half years later in 24% of SARS-CoV-2 infected individuals. Given the amount of time between infection and testing, it is possible that the olfactory problems may not be fully reversible in a plurality of individuals.


Assuntos
COVID-19 , Pessoal de Saúde , Transtornos do Olfato , SARS-CoV-2 , Humanos , COVID-19/epidemiologia , COVID-19/complicações , Masculino , Feminino , Transtornos do Olfato/epidemiologia , Transtornos do Olfato/etiologia , Transtornos do Olfato/virologia , Adulto , Prevalência , Estudos de Casos e Controles , Pessoa de Meia-Idade , SARS-CoV-2/isolamento & purificação , Olfato/fisiologia
2.
Brain Behav ; 14(7): e3597, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38956811

RESUMO

INTRODUCTION: Chemosensory function in pregnant women is far from being fully understood due to the lack of data and inconsistencies between the results of self-reports and objective studies. METHODS: In the present study in pregnant and non-pregnant women (npregnant = 14, nnon-pregnant = 13), we measured EEG-derived electrophysiological response measures supported by psychophysical olfactory and trigeminal tests. RESULTS: Results indicate that the olfactory event-related potential amplitudes or latencies of the P1, N1, and P2 components remain unchanged in pregnant women. In accordance with these findings, no difference was observed between pregnant and non-pregnant women in psychophysical olfactory tests. However, pregnant women displayed a lower degree of sensitivity to trigeminal stimuli compared to non-pregnant controls, which was also reflected in the electrophysiological responses to trigeminal stimuli. CONCLUSION: Counterintuitive as they may seem, our findings demonstrate a "flattening" of chemosomatosensory responses. Psychological processes occurring during pregnancy, such as changes in socioemotional perception of odors resulting from the diminished stress response, may provide a background to these results. Overall, the present results indicate the absence of major differences between non-pregnant and pregnant women in terms of measured olfactory function though chemosomatosensory function of the pregnant women appears to be decreased.


Assuntos
Eletroencefalografia , Nervo Trigêmeo , Humanos , Feminino , Gravidez , Adulto , Nervo Trigêmeo/fisiologia , Eletroencefalografia/métodos , Potenciais Evocados/fisiologia , Adulto Jovem , Percepção Olfatória/fisiologia , Olfato/fisiologia , Odorantes
3.
J Texture Stud ; 55(4): e12849, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38961563

RESUMO

While taste and smell perception have been thoroughly investigated, our understanding of oral somatosensory perception remains limited. Further, assessing and measuring individual differences in oral somatosensory perception pose notable challenges. This review aimed to evaluate the existing methods to assess oral somatosensory perception by examining and comparing the strengths and limitations of each method. The review highlighted the lack of standardized assessment methods and the various procedures within each method. Tactile sensitivity can be assessed using several methods, but each method measures different tactile dimensions. Further investigations are needed to confirm its correlation with texture sensitivity. In addition, measuring a single textural attribute may not provide an overall representation of texture sensitivity. Thermal sensitivity can be evaluated using thermal-change detection or temperature discrimination tests. The chemesthetic sensitivity tests involve either localized or whole-mouth stimulation tests. The choice of an appropriate method for assessing oral somatosensory sensitivity depends on several factors, including the specific research objectives and the target population. Each method has its unique intended purpose, strengths, and limitations, so no universally superior approach exists. To overcome some of the limitations associated with certain methods, the review offers alternative or complementary approaches that could be considered. Researchers can enhance the comprehensive assessment of oral somatosensory sensitivity by carefully selecting and potentially combining methods. In addition, a standardized protocol remains necessary for each method.


Assuntos
Boca , Percepção do Tato , Humanos , Percepção do Tato/fisiologia , Boca/fisiologia , Individualidade , Percepção Gustatória/fisiologia , Tato/fisiologia , Paladar/fisiologia , Limiar Sensorial/fisiologia , Olfato/fisiologia , Sensação Térmica/fisiologia
4.
Nat Commun ; 15(1): 5572, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38956072

RESUMO

Olfaction is influenced by contextual factors, past experiences, and the animal's internal state. Whether this information is integrated at the initial stages of cortical odour processing is not known, nor how these signals may influence odour encoding. Here we revealed multiple and diverse non-olfactory responses in the primary olfactory (piriform) cortex (PCx), which dynamically enhance PCx odour discrimination according to behavioural demands. We performed recordings of PCx neurons from mice trained in a virtual reality task to associate odours with visual contexts to obtain a reward. We found that learning shifts PCx activity from encoding solely odours to a regime in which positional, contextual, and associative responses emerge on odour-responsive neurons that become mixed-selective. The modulation of PCx activity by these non-olfactory signals was dynamic, improving odour decoding during task engagement and in rewarded contexts. This improvement relied on the acquired mixed-selectivity, demonstrating how integrating extra-sensory inputs in sensory cortices can enhance sensory processing while encoding the behavioural relevance of stimuli.


Assuntos
Odorantes , Recompensa , Olfato , Animais , Camundongos , Olfato/fisiologia , Masculino , Córtex Olfatório/fisiologia , Córtex Piriforme/fisiologia , Camundongos Endogâmicos C57BL , Percepção Olfatória/fisiologia , Neurônios/fisiologia , Feminino , Discriminação Psicológica/fisiologia
5.
Sci Rep ; 14(1): 15059, 2024 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-38956288

RESUMO

Although validated and reliable psychophysical tests of olfactory function are available, an easy-to-use and feasible test has yet to be developed. This study aimed to design a digital odour identification test, evaluate its validity, assess its reliability, establish a normative curve, and explore the impact of demographic factors. The odour identification test was presented with the Multiscent-20, a hand-held, tablet-like digital scent device that features an integrated odour digital delivery system. The identification performance on the 20 odours was assessed using item response theory (IRT). The normative curve was established by administering the test to a large sample of participants (n = 1299). The mean identification score was 17.5 (SD = 2.1). The two-parameter logistic IRT model provided the best fit, revealing variation in item discrimination and difficulty parameters. Educational attainment influenced performance, with primary education associated with lower scores. Additionally, sex was not found to be associated with performance. This study provides initial evidence supporting the validity and reliability of use of the Multiscent-20 as a digital odour identification test. The test's automation and portability enable the standardized delivery of olfactory stimuli and efficient automatic recording and scoring of responses.


Assuntos
Odorantes , Olfato , Humanos , Masculino , Feminino , Odorantes/análise , Adulto , Pessoa de Meia-Idade , Olfato/fisiologia , Adulto Jovem , Adolescente , Reprodutibilidade dos Testes , Idoso
6.
J R Soc Interface ; 21(216): 20230746, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39013419

RESUMO

Navigation of male moths towards females during the mating search offers a unique perspective on the exploration-exploitation (EE) model in decision-making. This study uses the EE model to explain male moth pheromone-driven flight paths. Wind tunnel measurements and three-dimensional tracking using infrared cameras have been leveraged to gain insights into male moth behaviour. During the experiments in the wind tunnel, disturbance to the airflow has been added and the effect of increased fluctuations on moth flights has been analysed, in the context of the proposed EE model. The exploration and exploitation phases are separated using a genetic algorithm to the experimentally obtained dataset of moth three-dimensional trajectories. First, the exploration-to-exploitation rate (EER) increases with distance from the source of the female pheromone is demonstrated, which can be explained in the context of the EE model. Furthermore, our findings reveal a compelling relationship between EER and increased flow fluctuations near the pheromone source. Using an olfactory navigation simulation and our moth-inspired navigation model, the phenomenon where male moths exhibit an enhanced EER as turbulence levels increase is explained. This research extends our understanding of optimal navigation strategies based on general biological EE models and supports the development of bioinspired navigation algorithms.


Assuntos
Voo Animal , Modelos Biológicos , Mariposas , Animais , Masculino , Mariposas/fisiologia , Feminino , Voo Animal/fisiologia , Olfato/fisiologia , Navegação Espacial/fisiologia , Comportamento Sexual Animal/fisiologia , Atrativos Sexuais
7.
Chem Senses ; 492024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38985657

RESUMO

Experience plays a pivotal role in determining our food preferences. Consuming food generates odor-taste associations that shape our perceptual judgements of chemosensory stimuli, such as their intensity, familiarity, and pleasantness. The process of making consummatory choices relies on a network of brain regions to integrate and process chemosensory information. The mediodorsal thalamus is a higher-order thalamic nucleus involved in many experience-dependent chemosensory behaviors, including olfactory attention, odor discrimination, and the hedonic perception of flavors. Recent research has shown that neurons in the mediodorsal thalamus represent the sensory and affective properties of experienced odors, tastes, and odor-taste mixtures. However, its role in guiding consummatory choices remains unclear. To investigate the influence of the mediodorsal thalamus in the consummatory choice for experienced odors, tastes, and odor-taste mixtures, we pharmacologically inactivated the mediodorsal thalamus during 2-bottle brief-access tasks. We found that inactivation altered the preference for specific odor-taste mixtures, significantly reduced consumption of the preferred taste and increased within-trial sampling of both chemosensory stimulus options. Our results show that the mediodorsal thalamus plays a crucial role in consummatory decisions related to chemosensory preference and attention.


Assuntos
Preferências Alimentares , Paladar , Animais , Ratos , Masculino , Paladar/fisiologia , Preferências Alimentares/fisiologia , Odorantes , Olfato/fisiologia , Tálamo/fisiologia , Ratos Long-Evans , Núcleo Mediodorsal do Tálamo/fisiologia
8.
NPJ Syst Biol Appl ; 10(1): 76, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39019918

RESUMO

Predicting olfactory perceptions from odorant molecules is challenging due to the complex and potentially discontinuous nature of the perceptual space for smells. In this study, we introduce a deep learning model, Mol-PECO (Molecular Representation by Positional Encoding of Coulomb Matrix), designed to predict olfactory perceptions based on molecular structures and electrostatics. Mol-PECO learns the efficient embedding of molecules by utilizing the Coulomb matrix, which encodes atomic coordinates and charges, as an alternative of the adjacency matrix and its Laplacian eigenfunctions as positional encoding of atoms. With a comprehensive dataset of odor molecules and descriptors, Mol-PECO outperforms traditional machine learning methods using molecular fingerprints and graph neural networks based on adjacency matrices. The learned embeddings by Mol-PECO effectively capture the odor space, enabling global clustering of descriptors and local retrieval of similar odorants. This work contributes to a deeper understanding of the olfactory sense and its mechanisms.


Assuntos
Odorantes , Percepção Olfatória , Eletricidade Estática , Odorantes/análise , Percepção Olfatória/fisiologia , Humanos , Aprendizado Profundo , Estrutura Molecular , Redes Neurais de Computação , Aprendizado de Máquina , Olfato/fisiologia , Algoritmos
9.
Parasit Vectors ; 17(1): 308, 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-39026238

RESUMO

BACKGROUND: Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae) is the main causative agent of flystrike of sheep in Australia and New Zealand. Female flies lay eggs in an open wound or natural orifice, and the developing larvae eat the host's tissues, a condition called myiasis. To improve our understanding of host-seeking behavior, we quantified gene expression in male and female antennae based on their behavior. METHODS: A spatial olfactometer was used to evaluate the olfactory response of L. cuprina mated males and gravid females to fresh or rotting beef. Antennal RNA-Seq analysis was used to identify sensory receptors differentially expressed between groups. RESULTS: Lucilia cuprina females were more attracted to rotten compared to fresh beef (> fivefold increase). However, males and some females did not respond to either type of beef. RNA-Seq analysis was performed on antennae dissected from attracted females, non-attracted females and males. Transcripts encoding sensory receptors from 11 gene families were identified above a threshold (≥ 5 transcript per million) including 49 ATP-binding cassette transporters (ABCs), two ammonium transporters (AMTs), 37 odorant receptors (ORs), 16 ionotropic receptors (IRs), 5 gustatory receptors (GRs), 22 odorant-binding proteins (OBPs), 9 CD36-sensory neuron membrane proteins (CD36/SNMPs), 4 chemosensory proteins (CSPs), 4 myeloid lipid-recognition (ML) and Niemann-Pick C2 disease proteins (ML/NPC2), 2 pickpocket receptors (PPKs) and 3 transient receptor potential channels (TRPs). Differential expression analyses identified sex-biased sensory receptors. CONCLUSIONS: We identified sensory receptors that were differentially expressed between the antennae of both sexes and hence may be associated with host detection by female flies. The most promising for future investigations were as follows: an odorant receptor (LcupOR46) which is female-biased in L. cuprina and Cochliomyia hominivorax Coquerel, 1858; an ABC transporter (ABC G23.1) that was the sole sensory receptor upregulated in the antennae of females attracted to rotting beef compared to non-attracted females; a female-biased ammonia transporter (AMT_Rh50), which was previously associated with ammonium detection in Drosophila melanogaster Meigen, 1830. This is the first report suggesting a possible role for ABC transporters in L. cuprina olfaction and potentially in other insects.


Assuntos
Antenas de Artrópodes , Calliphoridae , Perfilação da Expressão Gênica , Animais , Feminino , Masculino , Antenas de Artrópodes/metabolismo , Calliphoridae/genética , Miíase/veterinária , Miíase/parasitologia , Transcriptoma , Ovinos/parasitologia , Austrália , Nova Zelândia , Olfato , Receptores Odorantes/genética , Receptores Odorantes/metabolismo
10.
Int J Mol Sci ; 25(13)2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-39000230

RESUMO

In insect olfaction, sensitization refers to the amplification of a weak olfactory signal when the stimulus is repeated within a specific time window. In the vinegar fly, Drosophila melanogaster, this occurs already at the periphery, at the level of olfactory sensory neurons (OSNs) located in the antenna. In our study, we investigate whether sensitization is a widespread property in a set of seven types of OSNs, as well as the mechanisms involved. First, we characterize and compare the differences in spontaneous activity, response velocity and response dynamics, among the selected OSN types. These express different receptors with distinct tuning properties and behavioral relevance. Second, we show that sensitization is not a general property. Among our selected OSN types, it occurs in those responding to more general food odors, while OSNs involved in very specific detection of highly specific ecological cues like pheromones and warning signals show no sensitization. Moreover, we show that mitochondria play an active role in sensitization by contributing to the increase in intracellular Ca2+ upon weak receptor activation. Thus, by using a combination of single sensillum recordings (SSRs), calcium imaging and pharmacology, we widen the understanding of how the olfactory signal is processed at the periphery.


Assuntos
Drosophila melanogaster , Neurônios Receptores Olfatórios , Olfato , Animais , Neurônios Receptores Olfatórios/fisiologia , Neurônios Receptores Olfatórios/metabolismo , Drosophila melanogaster/fisiologia , Olfato/fisiologia , Odorantes , Cálcio/metabolismo , Plasticidade Neuronal/fisiologia , Receptores Odorantes/metabolismo , Mitocôndrias/metabolismo
11.
Front Neural Circuits ; 18: 1414452, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38978957

RESUMO

As an evolutionarily ancient sense, olfaction is key to learning where to find food, shelter, mates, and important landmarks in an animal's environment. Brain circuitry linking odor and navigation appears to be a well conserved multi-region system among mammals; the anterior olfactory nucleus, piriform cortex, entorhinal cortex, and hippocampus each represent different aspects of olfactory and spatial information. We review recent advances in our understanding of the neural circuits underlying odor-place associations, highlighting key choices of behavioral task design and neural circuit manipulations for investigating learning and memory.


Assuntos
Odorantes , Animais , Condutos Olfatórios/fisiologia , Olfato/fisiologia , Humanos , Percepção Olfatória/fisiologia , Percepção Espacial/fisiologia , Encéfalo/fisiologia
12.
Front Neural Circuits ; 18: 1437575, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39036422

RESUMO

The olfactory system plays crucial roles in perceiving and interacting with their surroundings. Previous studies have deciphered basic odor perceptions, but how information processing in the olfactory system is associated with learning and memory is poorly understood. In this review, we summarize recent studies on the anatomy and functional dynamics of the mouse olfactory learning pathway, focusing on how neuronal circuits in the olfactory bulb (OB) and olfactory cortical areas integrate odor information in learning. We also highlight in vivo evidence for the role of the lateral entorhinal cortex (LEC) in olfactory learning. Altogether, these studies demonstrate that brain regions throughout the olfactory system are critically involved in forming and representing learned knowledge. The role of olfactory areas in learning and memory, and their susceptibility to dysfunction in neurodegenerative diseases, necessitate further research.


Assuntos
Aprendizagem , Condutos Olfatórios , Animais , Aprendizagem/fisiologia , Condutos Olfatórios/fisiologia , Bulbo Olfatório/fisiologia , Percepção Olfatória/fisiologia , Humanos , Olfato/fisiologia , Camundongos , Córtex Olfatório/fisiologia , Córtex Entorrinal/fisiologia
13.
Genesis ; 62(3): e23611, 2024 06.
Artigo em Inglês | MEDLINE | ID: mdl-38888221

RESUMO

Olfactory sensory neurons (OSNs) are one of a few neuron types that are generated continuously throughout life in mammals. The persistence of olfactory sensory neurogenesis beyond early development has long been thought to function simply to replace neurons that are lost or damaged through exposure to environmental insults. The possibility that olfactory sensory neurogenesis may also serve an adaptive function has received relatively little consideration, largely due to the assumption that the generation of new OSNs is stochastic with respect to OSN subtype, as defined by the single odorant receptor gene that each neural precursor stochastically chooses for expression out of hundreds of possibilities. Accordingly, the relative birthrates of different OSN subtypes are predicted to be constant and impervious to olfactory experience. This assumption has been called into question, however, by evidence that the birthrates of specific OSN subtypes can be selectively altered by manipulating olfactory experience through olfactory deprivation, enrichment, and conditioning paradigms. Moreover, studies of recovery of the OSN population following injury provide further evidence that olfactory sensory neurogenesis may not be strictly stochastic with respect to subtype. Here we review this evidence and consider mechanistic and functional implications of the prospect that specific olfactory experiences can regulate olfactory sensory neurogenesis rates in a subtype-selective manner.


Assuntos
Neurogênese , Neurônios Receptores Olfatórios , Receptores Odorantes , Animais , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Neurônios Receptores Olfatórios/metabolismo , Neurônios Receptores Olfatórios/fisiologia , Neurogênese/genética , Olfato/fisiologia , Olfato/genética , Humanos
14.
Learn Mem ; 31(5)2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38862177

RESUMO

Associative learning enables the adaptive adjustment of behavioral decisions based on acquired, predicted outcomes. The valence of what is learned is influenced not only by the learned stimuli and their temporal relations, but also by prior experiences and internal states. In this study, we used the fruit fly Drosophila melanogaster to demonstrate that neuronal circuits involved in associative olfactory learning undergo restructuring during extended periods of low-caloric food intake. Specifically, we observed a decrease in the connections between specific dopaminergic neurons (DANs) and Kenyon cells at distinct compartments of the mushroom body. This structural synaptic plasticity was contingent upon the presence of allatostatin A receptors in specific DANs and could be mimicked optogenetically by expressing a light-activated adenylate cyclase in exactly these DANs. Importantly, we found that this rearrangement in synaptic connections influenced aversive, punishment-induced olfactory learning but did not impact appetitive, reward-based learning. Whether induced by prolonged low-caloric conditions or optogenetic manipulation of cAMP levels, this synaptic rearrangement resulted in a reduction of aversive associative learning. Consequently, the balance between positive and negative reinforcing signals shifted, diminishing the ability to learn to avoid odor cues signaling negative outcomes. These results exemplify how a neuronal circuit required for learning and memory undergoes structural plasticity dependent on prior experiences of the nutritional value of food.


Assuntos
Drosophila melanogaster , Corpos Pedunculados , Plasticidade Neuronal , Animais , Corpos Pedunculados/fisiologia , Corpos Pedunculados/metabolismo , Drosophila melanogaster/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios Dopaminérgicos/fisiologia , Neurônios Dopaminérgicos/metabolismo , Ingestão de Alimentos/fisiologia , Optogenética , Aprendizagem por Associação/fisiologia , Olfato/fisiologia , Percepção Olfatória/fisiologia , Recompensa , Animais Geneticamente Modificados
15.
Chem Senses ; 492024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38877790

RESUMO

SCENTinel, a rapid smell test designed to screen for olfactory disorders, including anosmia (no ability to smell an odor) and parosmia (distorted sense of smell), measures 4 components of olfactory function: detection, intensity, identification, and pleasantness. Each test card contains one of 9 odorant mixtures. Some people born with genetic insensitivities to specific odorants (i.e. specific anosmia) may fail the test if they cannot smell an odorant but otherwise have a normal sense of smell. However, using odorant mixtures has largely been found to prevent this from happening. To better understand whether genetic differences affect SCENTinel test results, we asked genetically informative adult participants (twins or triplets, N = 630; singletons, N = 370) to complete the SCENTinel test. A subset of twins (n = 304) also provided a saliva sample for genotyping. We examined data for differences between the 9 possible SCENTinel odors; effects of age, sex, and race on SCENTinel performance, test-retest variability; and heritability using both structured equation modeling and SNP-based statistical methods. None of these strategies provided evidence for specific anosmia for any of the odors, but ratings of pleasantness were, in part, genetically determined (h2 = 0.40) and were nominally associated with alleles of odorant receptors (e.g. OR2T33 and OR1G1; P < 0.001). These results provide evidence that using odorant mixtures protected against effects of specific anosmia for ratings of intensity but that ratings of pleasantness showed effects of inheritance, possibly informed by olfactory receptor genotypes.


Assuntos
Odorantes , Olfato , Humanos , Feminino , Masculino , Adulto , Odorantes/análise , Olfato/fisiologia , Pessoa de Meia-Idade , Transtornos do Olfato/diagnóstico , Transtornos do Olfato/genética , Adulto Jovem , Percepção Olfatória , Idoso , Genótipo , Anosmia/diagnóstico , Anosmia/genética
16.
Nat Commun ; 15(1): 4872, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38849331

RESUMO

Brain evolution has primarily been studied at the macroscopic level by comparing the relative size of homologous brain centers between species. How neuronal circuits change at the cellular level over evolutionary time remains largely unanswered. Here, using a phylogenetically informed framework, we compare the olfactory circuits of three closely related Drosophila species that differ in their chemical ecology: the generalists Drosophila melanogaster and Drosophila simulans and Drosophila sechellia that specializes on ripe noni fruit. We examine a central part of the olfactory circuit that, to our knowledge, has not been investigated in these species-the connections between projection neurons and the Kenyon cells of the mushroom body-and identify species-specific connectivity patterns. We found that neurons encoding food odors connect more frequently with Kenyon cells, giving rise to species-specific biases in connectivity. These species-specific connectivity differences reflect two distinct neuronal phenotypes: in the number of projection neurons or in the number of presynaptic boutons formed by individual projection neurons. Finally, behavioral analyses suggest that such increased connectivity enhances learning performance in an associative task. Our study shows how fine-grained aspects of connectivity architecture in an associative brain center can change during evolution to reflect the chemical ecology of a species.


Assuntos
Evolução Biológica , Drosophila , Corpos Pedunculados , Especificidade da Espécie , Animais , Corpos Pedunculados/fisiologia , Corpos Pedunculados/citologia , Corpos Pedunculados/anatomia & histologia , Drosophila/fisiologia , Drosophila/anatomia & histologia , Neurônios/fisiologia , Drosophila melanogaster/fisiologia , Drosophila melanogaster/anatomia & histologia , Filogenia , Olfato/fisiologia , Odorantes , Condutos Olfatórios/fisiologia , Condutos Olfatórios/anatomia & histologia , Masculino , Feminino , Terminações Pré-Sinápticas/fisiologia
17.
Front Neural Circuits ; 18: 1408189, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38872907

RESUMO

Olfactory dysfunctions decrease daily quality of life (QOL) in part by reducing the pleasure of eating. Olfaction plays an essential role in flavor sensation and palatability. The decreased QOL due to olfactory dysfunction is speculated to result from abnormal neural activities in the olfactory and limbic areas of the brain, as well as peripheral odorant receptor dysfunctions. However, the specific underlying neurobiological mechanisms remain unclear. As the olfactory tubercle (OT) is one of the brain's regions with high expression of endogenous opioids, we hypothesize that the mechanism underlying the decrease in QOL due to olfactory dysfunction involves the reduction of neural activity in the OT and subsequent endogenous opioid release in specialized subregions. In this review, we provide an overview and recent updates on the OT, the endogenous opioid system, and the pleasure systems in the brain and then discuss our hypothesis. To facilitate the effective treatment of olfactory dysfunctions and decreased QOL, elucidation of the neurobiological mechanisms underlying the pleasure of eating through flavor sensation is crucial.


Assuntos
Tubérculo Olfatório , Peptídeos Opioides , Qualidade de Vida , Olfato , Humanos , Animais , Olfato/fisiologia , Peptídeos Opioides/metabolismo , Peptídeos Opioides/fisiologia , Tubérculo Olfatório/fisiologia , Tubérculo Olfatório/metabolismo , Transtornos do Olfato/fisiopatologia , Transtornos do Olfato/metabolismo
18.
Curr Protoc ; 4(6): e1072, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38884352

RESUMO

Working memory capacity (WMC), a crucial component of working memory (WM), has consistently drawn the attention of researchers. Exploring the underlying neurobiological mechanisms behind it is currently a prominent focus in the field of neuroscience. Previously, we developed a novel behavioral paradigm for rodents called the olfactory working memory capacity (OWMC) paradigm, which serves as an effective tool for quantifying the WMC of rodents. The OWMC task comprises five phases: context adaptation, digging training, rule-learning for nonmatching to a single sample odor (NMSS), rule-learning for nonmatching to multiple sample odors (NMMS), and capacity testing. In the first phase, mice are handled to reduce stress and acclimate to the training cage. The second phase involves training mice to dig in a bowl of unscented sawdust to locate a piece of cheese. In the third phase, mice are trained to locate the cheese pellet in a bowl with a noveal odor. The fourth phase requires mice to distinguish the novel odor among multiple scented bowls to locate the cheese pellet. Finally, in the fifth phase, mice undergo several WMC tests until they achieve a stable level of performance. In this protocol paper, we will provide detailed instructions on how to implement the behavioral paradigm. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Context adaptation Basic Protocol 2: Digging training Basic Protocol 3: Rule-learning for NMSS Basic Protocol 4: Rule-learning for NMMS Basic Protocol 5: Capacity testing.


Assuntos
Memória de Curto Prazo , Odorantes , Memória de Curto Prazo/fisiologia , Animais , Camundongos , Odorantes/análise , Comportamento Animal/fisiologia , Olfato/fisiologia , Percepção Olfatória/fisiologia
19.
Sci Adv ; 10(25): eadn0014, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38905346

RESUMO

The central nervous system coordinates peripheral cellular stress responses, including the unfolded protein response of the mitochondria (UPRMT); however, the contexts for which this regulatory capability evolved are unknown. UPRMT is up-regulated upon pathogenic infection and in metabolic flux, and the olfactory nervous system has been shown to regulate pathogen resistance and peripheral metabolic activity. Therefore, we asked whether the olfactory nervous system in Caenorhabditis elegans controls the UPRMT cell nonautonomously. We found that silencing a single inhibitory olfactory neuron pair, AWC, led to robust induction of UPRMT and reduction of oxidative phosphorylation dependent on serotonin signaling and parkin-mediated mitophagy. Further, AWC ablation confers resistance to the pathogenic bacteria Pseudomonas aeruginosa partially dependent on the UPRMT transcription factor atfs-1 and fully dependent on mitophagy machinery. These data illustrate a role for the olfactory nervous system in regulating whole-organism mitochondrial dynamics, perhaps in preparation for postprandial metabolic stress or pathogenic infection.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Mitocôndrias , Mitofagia , Olfato , Animais , Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Mitocôndrias/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Olfato/fisiologia , Resposta a Proteínas não Dobradas , Pseudomonas aeruginosa/fisiologia , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , Fosforilação Oxidativa , Transdução de Sinais , Serotonina/metabolismo , Fatores de Transcrição
20.
Nutrients ; 16(11)2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38892664

RESUMO

Aging is a progressive physiological degeneration associated with a decline in chemosensory processes and cognitive abilities and a reduction in synaptic plasticity. The biological bases of ageing are still not completely understood, and many theories have been proposed. This study aimed to evaluate the occurrence of age-related changes affecting the chemosensory function (gustatory and olfactory) and general cognitive abilities and their potential associations in women. To this aim, 319 women (the age ranging from 18 to 92 years) were recruited and divided into four different age groups: 18-34 years, 35-49 years, 50-64 years, and ≥65 years. Our results confirmed that in women, gustatory, olfactory, and cognitive functions decline, though in a different manner during aging. Olfactory and cognitive function showed a slight decline along the first three age classes, with a dramatic decrease after age 65 years, while gustatory function decreased more gradually. Olfactory and gustatory deficits may have a high degree of predictivity for general cognitive function as well as for specific cognitive subdomains such as visuospatial/executive abilities, language, memory, and attention. Our study highlighted the importance of using chemosensory assessments for the early diagnosis of cognitive decline and for the development of appropriate personalized risk prevention strategies.


Assuntos
Envelhecimento , Cognição , Olfato , Paladar , Humanos , Feminino , Pessoa de Meia-Idade , Adulto , Cognição/fisiologia , Idoso , Adulto Jovem , Adolescente , Envelhecimento/fisiologia , Olfato/fisiologia , Idoso de 80 Anos ou mais , Paladar/fisiologia , Disfunção Cognitiva/epidemiologia , Fatores Etários
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