Дисертації з теми "Sensitivity olfactory"

The purpose of the present study was to determine olfactory detection thresholds in human subjects for a set of six sulfur-containing odorants which are known to be components of mammalian predator odors. Using a threealternative ascending staircase procedure, the olfactory sensitivity of 12 healthy adult human subjects, 6 males and 6 females was assessed with 2-propylthietane, 2,2-dimethylthietane, 3-mercapto-3-methylbutan-1-ol, 3-mercapto-3- methylbutyl formate, 3-methyl-1-butanethiol, and methyl-2-phenylethyl sulfide. The results showed that A) all six predator odorants were detected at concentrations below 1 ppb (parts per billion), and one of them (3-mercapto-3-methylbutyl formate) even at a concentration below 1 ppt (parts per trillion), B) structurally similar odorants yielded significantly different threshold values, and C) no significant sex differences were found in olfactory sensitivity with any of the six odorants. The findings obtained from the present study show that human subjects were not generally less sensitive to the predator odorants tested here compared to spider monkeys despite having a markedly lower number of olfactory receptor types. Further, they suggest that humans may be more sensitive to predator odorants compared to a variety of non-predator odorants. One possible explanation for the high olfactory sensitivity observed here is the fact that sulfur compounds typically can be detected at low concentrations. An alternative explanation derives from an evolutionary perspective as our human ancestors were a potential prey of large carnivores and  thus a high olfactory sensitivity for predator odors should be adaptive for humans.

Primates have traditionally been viewed as having a poorly developed sense of smell. However, in recent years, studies have shown that at least some primate species use olfaction in a number of behaviors, and that they have a high olfactory sensitivity for various chemical classes of odorants. Using a two-choice instrumental conditioning paradigm, the present study assessed olfactor ydetection thresholds of three spider monkeys (Ateles geoffroyi) for eight aliphatic alcohols and aldehydes, known as "green odors". With all odorants, the animals detected concentrations below 1 parts per million, with single individuals performing even better. The type of functional group present systematically affected olfactory detection thresholds, whereas the presence, position and configuration of a double bond did not. Compared to previously tested classes of odorants, thespider monkeys were not particularly sensitive to "green odors". Furthermore, they are lesssensitive for "green odors" compared to humans and mice. The present results suggest that neuroanatomical and genetic comparisons across species are poor predictors of olfactory sensitivity.

Massive convergence of input from olfactory receptor neurons (ORNs) with identical tunings leads to spatial integration of sensory signals, thereby boosting sensitivity to sensory cues. The consequent reduction in detection thresholds is assumed to derive from the pooling of elevated firing rates across the ORN population. By comparing detection thresholds at the first two stages of the olfactory pathway in an olfactory specialist, the moth, allowed for the quantification of the sensitivity boost achieved during early sensory processing. This boost was found to be at least 3 orders of magnitude, which was shown to exceed that achieved by a theoretical model of spike train integration. The sensitivity enhancement achieved by this system therefore goes beyond straightforward spatial summation of receptor firing rates, suggesting subtler coding and readout mechanisms. To discount the possibility of ORNs employing a temporal encoding scheme, an inves tigation into spike patterns at the periphery was performed. While no temporal patterns were evident, a temporal encoding scheme remains a possibility. Despite the inconclusive result found here, the analysis demonstrates the need for an investigation of the stationar- ity of spike trains, where a statistical basis underlies the analysis method, before drawing conclusions. Regardless of the encoding scheme employed at the periphery, due to the multitude of possible synaptic connections within a glomerulus, it seems unlikely that this site of conver gence of receptor input would be passive. A simple, but biologically plausible computational model was developed, where specific zones of the dendritic tree of an output neuron form individual subunits capable of performing a nonlinear threshold function on ORN inputs. This nonlinear model consistently outperformed a comparable linear model when assessing the stimulus detection performance of the output neuron.

The present study aimed at assessing possible gender differences in human olfactory detection thresholds for three odorants; bourgeonal, an aromatic aldehyde, helional, a structural analogue of bourgeonal,  and n-pentyl acetate, an aliphatic ester. A total of 500 subjects, 250 males and 250 females between 18 and 40 years of age, were tested using a triangular forced choice method with an ascending staircase procedure. The subjects were asked to sniff the contents of three bottles and to identify the one containing the stimulus presented at a given concentration. Males were found to have a significantly lower olfactory detection threshold for bourgeonal compared to females (3.4·10¹¹ molecules·cm^-3 air and 5.9·10¹¹ molecules·cm^-3 air, respectively) whereas no significant gender difference in the olfactory detection thresholds for helional (1.4·10¹³ molecules cm^-3 air and  1.3·10¹³ molecules·cm^-3 air, respectively) or n-pentyl acetate (1.4·10¹⁴ molecules·cm^-3 air and  1.1·10¹⁴ molecules·cm^-3 air , respectively) were found. This is the first study ever to report a human male superiority in olfactory sensitivity for a monomolecular odorant. One possible explanation for this finding is that bourgeonal may differ in its biological significance for males and females. It has recently been demonstrated that bourgeonal elicits chemotaxis in human sperm cells and olfactory receptors activated by bourgeonal might thus be subject to sexual selection.

This thesis is an investigation into the potential mechanisms that could explain the olfactory sensitivity to thiol compounds ~ought to be conserved across mammalian species. Proteomics techniques were employed as unbiased tools to search for highly conserved proteins in olfactory cilia theoretically capable of strong interactions with thiol odorants. Comparisons of the protein profiles and directed protein labelling studies of olfactory cilia from three mammalian species - the house mouse (Mus musculus), the rat (Rattus norvegicus) and the sheep (Ovis aries) - and respiratory cilia preparations from the rat enabled the identification of cytoskeletal proteins and olfactory receptors as potential targets for sulphydryl-mediated thiol odorant interactions. It is therefore predicted that olfactory detection of thiol odorants utilises a traditional olfactory receptor conserved across mammalian. species, the observed thiol sensitivity potentially a byproduct of a strong interaction between odorant and receptor. This study also represents the first broad ranging study of the protein complement of mammalian olfactory cilia derived from the three model species. The characterisation of olfactory and respiratory cilia proteomes from multiple mammalian species has highlighted a novel family of putative pheromone binding proteins uniquely associated with mouse olfactory cilia preparations. It has also provided further evidence for the ongoing investigations of the functions of odorant-binding proteins and annexins.

In this article an attempt is made to standardize the results of diagnosis of olfactory analyzer disorders. For the development of the integral indicator of olfactory sensitivity in order to formalize the diagnostic data on the basis of the method of increasing the objectivity of alfakometric studies, weighting coefficients were determined based on the method of attribution of points. A questionnaire was prepared for our study.

For many years, primates have been considered to be animals with a poorly developed sense of smell. However, in recent years several studies have shown that at least some primate species have a high olfactory sensitivity for a variety of odorants. The present study used a two-choice instrumental conditioning paradigm to test the olfactory sensitivity for six aromatic aldehydes in four spider monkeys (Ateles geoffroyi). With helional, cyclamal,canthoxal and lilial all animals discriminated concentrations below 1 ppm from the odorless solvent, with single individuals even scoring better. With 3-phenyl-propionic aldehyde all animals detected concentrations below 2 ppb, and with bourgeonal even below 0.3 ppb. The detection thresholds of the odorants changed systematically with molecular structure. Addition of a dioxo or methoxy group to the benzene ring led to an increase in threshold values,while the absence of a methyl group close to the aldehyde moiety was linked to a low threshold value for the odorant. The study shows that spider monkeys have a well developed olfactory sensitivity for aromatic aldehydes.

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and, the Woods Hole Oceanographic Institution), 2005.
Handwritten on CDROMS: v. [1]. Appendix, histological images -- v. [2]. CT images. -- Table of contents refers to CDROMS as: Appendix and CT and histological images for all species, attached CD)
Includes bibliographical references (v. 2, leaves 216-247).
In this thesis, the relationships of olfactory sensitivity to three biological variables were tested. The sensitivity of a marine mammal, the sea otter (Enhydra lutris) was measured in order to determine whether a marine lifestyle results in impaired olfaction. The effect of dietary relevance on sensitivity to specific odorants was evaluated. Finally, a new morphometric model of olfactory uptake efficiency was developed and tested against behavioral measurements of olfactory sensitivity in twelve mammalian species from five orders. Olfactory thresholds were obtained for the first time from two sea otters for seven odorant compounds from various natural sources. Otters were trained using operant conditioning to participate in direct behavioral testing. Sea otter olfactory sensitivity was comparable to that of previously studied terrestrial mammals. The incidence of an odorant in the diet of the olfactor was found to influence specific sensitivity to that compound but to varying degrees among different mammalian orders. Nasal cavity specimens were measured using radiologic (CT scan) and histologic (light microscopy) techniques. Surface areas and volumes of the nasal cavity were used to calculate the Olfactory Uptake Efficiency (OUE). OUE is significantly related to olfactory bulb volume. A possible relationship was found between OUE and general olfactory sensitivity.
by Jennifer Hammock.
Ph.D.

Olfactory identification deficits have received recent attention as a potentially useful endophenotype for schizophrenia. Examination of this deficit in individuals with schizotypal personality features (SPF) offers an alternative approach to multiple confounds present when examining individuals with schizophrenia. The aim of the current study was to compare the relative sensitivity of performance on measures of olfaction identification and sustained attention to the presence of SPF. Twenty-six undergraduates were defined as having SPF based on scoring in the top 10% of the Abbreviated Schizotypal Personality Questionnaire (SPQ-B; mean age 19.6, SD = 1.1; 62% female). These individuals were compared to twenty-six controls (scoring lower than half a standard deviation above the mean; mean age 19.8, SD = 1.6; 62% female). All participants were administered the Schizotypal Personality Disorder (SPD) section of the Structured Clinical Interview for DSM IV Axis II Personality Disorders (SCID-II). In addition, participants were administered the Brief Smell Identification Test (B-SIT) and a six-minute degraded-stimuli Continuous Performance Test (CPT). Group differences in performance indices of the CPT did not approach statistical significance. Similarly, there were no statistically significant group differences for males or females in performance on the B-SIT. Correlational analyses examined cognitive performance with a dimension score derived by summing quantitative ratings from the SPD items on the SCID-II. The SPD dimension score showed a statistically significant positive correlation with several performance indices of the CPT, including omission errors (rs(52) = .51, p < .001) and commission errors (rs(52) = .38, p < .005). In contrast, the B-SIT scores were not correlated with the SPD dimension score for males or females. Contrary to our hypothesis, results from the current study suggest that olfactory identification deficits may not represent a robust endophenotype consistently found in samples with schizotypal personality features. With regard to sustained attention, our differential findings suggest that schizotypal traits may be more adequately assessed through an interview by trained clinicians who use clinical judgment to determine the presence of phenotypic aspects of SPD (e.g., SCID-II), rather than relying on self-report measures (e.g., SPQ-B). Implications as well as limitations and future directions of these findings are discussed.
M.S.
Department of Psychology
Sciences
Psychology PhD

Using a conditioning paradigm and an automated olfactometer, I investigated the olfactory sensitivity of five CD-1 mice for seven aromatic aldehydes. With two of the stimuli (3-phenylpropanal and canthoxal), the animals discriminated concentrations as low as 10 ppb (parts per billion) from the odorless solvent and with four of the stimuli (helional, cyclamal, lilial and lyral) they discriminated concentrations as low as 1 ppb, with single individuals even scoring better. All five animals yielded the by far lowest threshold value with bourgeonal and discriminated a concentration of 0.1 ppq (parts per quadrillion) from the odorless solvent. The detection threshold values for aromatic aldehydes were found to be affected by the type of functional groups and oxygen moiety attached to the benzene ring. A comparison of the present data with those obtained in other species found no clear correlation between olfactory sensitivity and the size of the olfactory receptor repertoire.

The chronically ill participants in this study are vulnerable experts in life’s uncertainties, and have become aware over time of multiple medical and social needs and practices. But, unlike the hypo-aware respondents documented in some studies of diabetes mellitus Type 1, these research participants are also conscious of their inability to recognise when their own fluctuating blood glucose levels are rising or falling to extremes, a loss of hyper- or hypo-awareness that puts their lives constantly at risk. Particular sources of better life management, increased self-esteem and means of social (re-)integration are trained medical alert assistance dogs who share the human home, and through keen olfactory sensitivity, are able to give advance warning when their partners’ blood sugar levels enter ‘danger’ zones. Research studies in anthrozoology and anthropology provide extensive literature on historic and contemporary human bonds with domestic and/or wild nonhuman animals. Equally, the sociology of health and illness continues to extend research into care practices performed to assist people with chronic illness. This study draws from these disciplines in order to add to multispecies ethnographic literature by exploring human-canine engagement, contribution and narrative, detailing the impact each member of the dyad has on the other, and by observing the 'doing' of the partnerships' daily routines to ward off hypo-glycaemia and hospitalisation. In addition, the project investigates the place, role and 'otherness' of a medical alert dog in a chronically ill person's understanding of 'the-body-they-do'. The perspective of symbolic interactionism assists in disentangling individual and shared meanings inherent in the interspecies collaboration by examining the mutualistic practices of care performed. The often-flexible moral boundaries that humans construct to differentiate between acceptable use and unacceptable exploitation of nonhuman animals are questioned within ethics-of-care theory, based on the concept of dogs as animate instruments and biomedical resources.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.17 – біологічні та медичні прилади і системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019. За відсутності сучасних доказових методів ольфактометрії доцільно розробляти методи та засоби респіраторно-ольфакторних порушень. У дисертаційній роботі подано розв'язання конкретного наукового завдання – розробка методів та засобів об'єктивного визначення респіраторно-ольфакторних порушень. На основі дослідження аеродинаміки носа на мікрорівні розроблено метод визначення ламінарного пограничного шару повітряного потоку у верхніх дихальних шляхах, що дозволяє за рахунок дослідження товщини пристінкової течії повітря відносно нерівномірності оболонки визначати патологічні ділянки носової порожнини за різних режимів дихання. Розроблено метод та засіб об'єктивної діагностики респіраторно-ольфакторних порушень, які дозволяють за рахунок визначення енергетичних характеристик носового дихання під час дії різних одорівекторів визначати на доказовому рівні відповідні пороги ольфакторної чутливості. Удосконалено метод визначення порогу ольфакторної чутливості, що дозволяє за рахунок аналізу форми циклограми носового дихання підвищити об'єктивність діагностики порушень нюхової чутливості або респіраторно-ольфакторних порушень.
The thesis of competition for the scientific degree of Candidate of Technical Sciences on specialty 05.11.17 – Biological and Medical Devices and Systems. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. In the absence of modern evidence-based methods of olfactometry, it is advisable to develop methods and means of respiratory and olfactory disorders. The dissertation is devoted to the solution of a specific scientific problem - the development of methods and means for the objective determination of respiratory and olfactory disorders. Based on the study of the aerodynamics of the nose at the micro level a method has been developed for determining the laminar boundary layer of the air flow in the upper respiratory tract, which makes it possible, by studying the thickness of the near-wall air flow relative to the unevenness of the mucous membrane, to determine the pathological regions of the nasal cavity in different breathing patterns. A method and means for objective diagnosis of respiratory and olfactory disorders have been developed, which allow, by determining the energy characteristics of nasal breathing under the action of various odorivectors, to determine the corresponding thresholds of olfactory sensitivity at an evidence-based level. The improved method for determining the threshold of olfactory sensitivity allows to increase the objectivity of diagnosing olfactory sensitivity disorders or respiratory olfactory disorders by analyzing the shape of the cycloramas of nasal breathing.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.17 – біологічні та медичні прилади і системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019. За відсутності сучасних доказових методів ольфактометрії доцільно розробляти методи та засоби респіраторно-ольфакторних порушень. У дисертаційній роботі подано розв'язання конкретного наукового завдання – розробка методів та засобів об'єктивного визначення респіраторно-ольфакторних порушень. На основі дослідження аеродинаміки носа на мікрорівні розроблено метод визначення ламінарного пограничного шару повітряного потоку у верхніх дихальних шляхах, що дозволяє за рахунок дослідження товщини пристінкової течії повітря відносно нерівномірності оболонки визначати патологічні ділянки носової порожнини за різних режимів дихання. Розроблено метод та засіб об'єктивної діагностики респіраторно-ольфакторних порушень, які дозволяють за рахунок визначення енергетичних характеристик носового дихання під час дії різних одорівекторів визначати на доказовому рівні відповідні пороги ольфакторної чутливості. Удосконалено метод визначення порогу ольфакторної чутливості, що дозволяє за рахунок аналізу форми циклограми носового дихання підвищити об'єктивність діагностики порушень нюхової чутливості або респіраторно-ольфакторних порушень.
The thesis of competition for the scientific degree of Candidate of Technical Sciences on specialty 05.11.17 – Biological and Medical Devices and Systems. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. In the absence of modern evidence-based methods of olfactometry, it is advisable to develop methods and means of respiratory and olfactory disorders. The dissertation is devoted to the solution of a specific scientific problem - the development of methods and means for the objective determination of respiratory and olfactory disorders. Based on the study of the aerodynamics of the nose at the micro level a method has been developed for determining the laminar boundary layer of the air flow in the upper respiratory tract, which makes it possible, by studying the thickness of the near-wall air flow relative to the unevenness of the mucous membrane, to determine the pathological regions of the nasal cavity in different breathing patterns. A method and means for objective diagnosis of respiratory and olfactory disorders have been developed, which allow, by determining the energy characteristics of nasal breathing under the action of various odorivectors, to determine the corresponding thresholds of olfactory sensitivity at an evidence-based level. The improved method for determining the threshold of olfactory sensitivity allows to increase the objectivity of diagnosing olfactory sensitivity disorders or respiratory olfactory disorders by analyzing the shape of the cycloramas of nasal breathing.

A diferença da percepção álgica entre homens e mulheres é, há muito, conhecida e documentada na literatura. Sabe-se também que a sensibilidade feminina varia durante o ciclo menstrual, o que levou à hipótese de que os hormônios ovarianos poderiam estar envolvidosnesse processo. Assim, este estudo teve como objetivo investigar os limiares de sensibilidade somestésica (térmica, dolorosa, tátil, vibratória e elétrica), gustativa e olfativa durante o ciclo menstrual de mulheres saudáveis e a sua relação com as concentrações dos hormônios estrógeno e progesterona na saliva. Foram avaliadas 39 mulheres com idade entre 19 e 47 anos, com ciclos menstruais regulares e sem morbidades associadas à dor. Todas as mulheres foram orientadas quanto aos propósitos desta pesquisa, e somente participaram do estudo aquelas que preencheram os critérios de inclusão e assinaram o termo de consentimento livre e esclarecido. A avaliação foi realizada em três momentos do ciclo menstrual: fase menstrual, fase folicular e fase lútea. Em cada uma dessas fases foram utilizados os seguintes métodos: coleta da saliva no início de cada sessão, para avaliação dos níveis hormonais; avaliação de fluxo salivar; avaliação sensitiva superficial (dor, tato - IITC Woodland Hills, EUA; frio, calor - MSA II e vibratórios - Somedic, Suécia) aplicada na região do ramo maxilar do nervo trigêmeo e na região do antebraço, ambas no lado direito da paciente; e avaliação das sensibilidades gustativa (doce - glicose, salgado - cloreto de sódio, azedo - ácido cítrico e amargo - ureia) e olfativa (isopropanol em diferentes concentrações). Foram observadas oscilações sensitivas em todas as modalidades de acordo com o momento do ciclo menstrual das mulheres avaliadas, sendo que níveis baixos de estrógeno se associaram a altos limiares de dor de profundidade no braço (p=0,008) e na face (p=0,041), altos limiares táteis (p=0,001) e álgicos superficiais (p=0,006) na face. Em contrapartida, altos níveis de progesterona se associaram a altos limiares de dor de profundidade na face (p=0,033) e altos limiares do sabor salgado (p < 0,001). Concluímos que o estrógeno e a progesterona estão envolvidos na neuromodulação da sensibilidade somestésica, gustativa e olfativa de mulheres, durante o ciclo menstrual
There is a sexual difference on pain perception that is supported by the scientific literature. Moreover, sexual hormones seem to be involved in the modulation of sensory detection and there is evidence of sensory variation during the menstrual cycle. Thus, the aim of this study was to investigate the somatosensory (thermal, painful, tactile, vibratory and electric), gustatory (salty, bitter, sweet, sour) and olfactory thresholds during the menstrual cycle in healthy women and verify association with saliva concentration of estradiol and progesterone. We evaluated 39 women aged between 19 and 47 years, with regular menstrual cycles and with no comorbidities related to pain.All women were instructed about the purposes of the study and only those that signed the informed consent were included. The evaluation wasperformed in three moments of the cycle: menstrual phase, follicular phase and luteal phase. In each of these stages, the following methods were used: saliva collection at the beginning of each session, to assess hormone levels; salivary flow measurement; somatosensory evaluation with quantitative sensory testing (pain, tactile - IITC Woodland Hills, USA; cold and warm - MSA II; and vibration - Somedic, Sweden) applied to the right maxillary branch region of the trigeminal nerve and right forearm region; and gustative (sweet - glucose, salt - sodium chloride, sour - citric acid and bitter - urea) and olfactory (isopropanol at different concentrations) thresholds. All sensory thresholds showed fluctuation during the menstrual cycle. Lower estrogen levels were correlated tohigher deep pain thresholds at the forearm (p=0.008) and face (p=0.041); they were also associated with higher tactile thresholds (p=0.001) and higher superficial pain (p=0.006) thresholds at face.High levels of progesterone were associated with high deep pain threshold at the face and high salty threshold (p < 0.001). In conclusion, estrogen and progesterone seems to be involved in sensory neuromodulation in women, during the menstrual cycle

Dopaminergic innervation of the entorhinal cortex may contribute to the integration and encoding of sensory information. The primary olfactory cortex (piriform cortex) projects to the superficial layers of the entorhinal cortex, and converging dopaminergic inputs from the ventral tegmental area may modulate processes in the entorhinal cortex related to the salience of olfactory stimuli. In the current study, food-restricted rats were trained to dig in cups filled with scented sand and to discriminate between two different odours to obtain a buried food-reward which was always associated with one odour (CS+). Upon reaching criterion performance on this task, animals underwent sham surgery or 6-hydroxydopamine lesions of the entorhinal cortex. After retraining on the original discrimination rule, olfactory sensitivity was tested using cups containing decreasing amounts of the original CS+ odour. Animals showed graded decrements in response accuracy as the concentration of odorant was reduced, but no significant differences were observed between control and lesioned animals. In addition, lesioned animals did not differ in their ability to learn to perform the discrimination task with a new odour pair at low concentrations, and did not show differences in their ability to respond accurately to either the initial or novel odour pair after a delay of two weeks. These findings show that scented sand can be used as an effective stimulus to assess the sensitivity to olfactory stimuli in the rat, but do not provide evidence for deficits in olfactory sensitivity or memory performance in animals with 6-OHDA lesions of the entorhinal cortex.

Olfaction plays an important role in human mate selection or in ratings of sexual attractiveness of potential mates. Many studies suggest that olfaction is associated with human sexuality and arousal as well, especially in women, for whom the perception of odors is an important aspect not only in mate selection, but also in sexual context. There are steroids called 16-androstenes, which have an unique importance in this issue. These steroids, produced by the apocrine glands, are compounds of human body odor. The aim of the empirical part of this thesis is to research the associations between olfactory abilities and sexual function in women, especially with particular focus on the association of olfactory sensitivity (particularly to androstadienone as well as in general), orgasmicity and arousal, which are two major domains of sexual function. Participants were 90 heterosexual and coupled female students aged 21-30. All participants were tested during the follicular phase of their menstrual cycle. The Sniffin Sticks olfactory test was employed to assess the general olfactory functions. Among others, olfactory sensitivity to androstadienone was measured, as well as the perceived intensity and hedonicity of androstenone, androstenol and andostadienone. Participants filled out set of questionnaires...