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At least 469 records · Page 26Linked to original sources
PubMed2005

Sniffing and spatiotemporal coding in olfaction.

The act of sniffing increases the air velocity and changes the duration of airflow in the nose. It is not yet clear how these changes interact with the intrinsic timing within the olfactory bulb, but this is a matter of current research activity. An action of sniffing in generating a high velocity that alters the sorption of odorants onto the lining of the nasal cavity is expected from the established work on odorant properties and sorption in the frog nose. Recent work indicates that the receptor properties in the olfactory epithelium and olfactory bulb are correlated with the receptor gene expression zones. The responses in both the epithelium and the olfactory bulb are predictable to a considerable extent by the hydrophobicity of odorants. Furthermore, receptor expression in both rodent and salamander nose interacts with the shapes of the nasal cavity to place the receptor sensitivity to odorants in optimal places according to the aerodynamic properties of the nose.

Animals↗
PubMed1990

smellblind: a gene required for Drosophila olfaction.

In this article we define and characterize the smellblind gene (sbl). We show that two mutants, sbl and olfDx9, both isolated by virtue of their olfactory phenotypes and analyzed extensively by others with respect to courtship behavior, contain mutations at a single locus. Meiotic recombination, duplication, and deficiency mapping are used to localize this gene, sbl, to cytogenetic position 14F6-15A2-3 on the X chromosome. Mutations of the locus are shown to produce severe defects not only in larval olfactory response to several volatile chemicals, but also in larval contact chemosensory response. Both sbl and olfDx9 give a robust response, however, in a new test of larval phototactic response, which we describe here. Both alleles are shown to be heat-sensitive lethals. Four additional recessive lethal alleles, two EMS-induced, one dysgenic, and one spontaneous, are also described.

Alleles↗
PubMedDate not supplied

Functional MRI of human olfaction.

PURPOSE: Our goal was to use functional MRI (fMRI) to measure brain activation in response to olfactory stimuli. METHOD: fMRI brain scans were obtained in 17 normal subjects (9 men, 8 women) using-multislice FLASH MRI in response to three olfactory stimuli (pyridine, menthone, amyl acetate) in three coronal brain sections selected from anterior to posterior temporal brain regions. Activation images were derived using correlation analysis, and ratios of areas of brain activated to total brain areas were calculated. RESULTS: Activation was present in each section in all subjects. Subjective estimation of vapor intensity followed relative vapor pressure of stimuli presented (pyridine > amyl acetate > menthone) and were similar for both men and women. However, brain activation did not follow subjective responsiveness order but rather pyridine > menthone > amyl acetate, a pattern demonstrated by both men and women. Brain activation in women was consistently lower than in men for all vapors in all brain sections, although regions of activation did not differ. Activation occurred in regions previously recognized as associated with olfactory stimulation, including orbitofrontal and entorhinal cortex; however, extensive regions within frontal cortex including cingulate gyrus were also activated. Brain regions activated to odors considered pleasant or unpleasant did not differ. CONCLUSION: The techniques used in this study demonstrated that brain activation to olfactory stimuli could be measured quantitatively such that differences between groups of subjects (in this case men and women) could be compared. Although localization of brain activation was not the major thrust of this study, activation to olfactory stimuli was found not only in brain regions previously associated with processing of olfactory information but also in several other areas of frontal cortex, in cingulate gyrus, and in several components of the limbic system. This is the first study in which activation in human brain parenchyma of normal humans to olfactory stimuli has been quantitated by fMRI.

Adult↗
PubMed1992

Mechanisms of sensitivity and specificity in olfaction.

The sensitivity and specificity of the mammalian olfactory system is the result of the contributions at the anatomical, cellular, and biochemical levels. The recent identification of a large gene family encoding putative olfactory receptors suggests that genetic diversity may play an important role in this system. Future challenges lie in understanding the mechanism that regulates expression of each of the receptors and establishes the complex neural processing network that interprets the primary neuronal responses.

Animals↗
PubMed1996

Le Nez du Vin--a quick test of olfaction.

There is a need for a quick and inexpensive smell identification test. A six odour multiple choice smell test derived from Le Nez du Vin, a winetaster's kit, is described. One hundred and thirty-two subjects assessed a mean of 5.28 +/- 1.18 odours correctly. There was a significant difference between those who considered themselves to have a normal sense of smell (n = 91), mean score 5.52 +/- 0.76, and those who thought themselves hyposmic (n = 41), mean score 4.76 +/- 1.68. (P < 0.001). No significant differences could be detected between the scores of smokers and non-smokers, nor those of males and females. Twenty-one patients performed both the Nez du Vin and University of Pennsylvania Smell Identification Test (UPSIT) in random order. Results of the two tests showed good correlation (r = 0.79, P < 0.001).

Adolescent↗
PubMed1989

The roles of vision and olfaction in mate location by males of the tsetse fly Glossina morsitans morsitans.

The roles of visual and/or olfactory stimuli in eliciting mating responses from male Glossina morsitans morsitans Westwood were examined, using a system for automatically recording the number and duration of mating strikes made towards decoys, under controlled conditions. The results confirm that there is no olfactory component of the female sex recognition pheromone sensed by the male antennae, and the attraction of males to females appears to be visual. The absence of male-male mating strikes was the result of the absence of female sex-pheromone, rather than the presence of a repellent mating deterrent in the male cuticle. Experiments with coloured, artificial, sex-pheromone-dosed, cotton decoys showed that colour had only weak effects on attractiveness and number of encounters with decoys, and that no colour caused significant enhancement of mating responses over those shown to decoy females.

Animals↗
PubMed1995

Effect of terfenadine and budesonide on nasal symptoms, olfaction, and nasal airway patency following allergen challenge.

The study investigated the effect of the oral H1-blocker terfenadine on allergen challenge in subjects with nasal allergy in comparison with the topical steroid, budesonide. A randomized, placebo-controlled, double-blind, crossover study with 3 experimental days was performed outside the pollen season. Seventeen nonsmokers with hay fever (symptoms, positive skin prick test, and RAST against timothy) were treated for 14 days before each experimental day, where the response to nasal challenge with four different concentrations of timothy was measured every 15 min for 6 h. The nasal cavity dimensions were measured by acoustic rhinometry and the olfactory function as the threshold for the sense of smell of butanol. Nasal symptoms were determined by questionnaires. Both terfenadine and budesonide dry powder had an effect on the hay fever symptoms during nasal pollen challenge. Terfenadine was more efficient than budesonide against histamine-mediated symptoms such as sneezing and itching. Budesonide increased nasal airway dimensions better than terfenadine (P < 0.01). A marked effect of budesonide was seen 1-2 h after challenge, suggesting an effect on "early late phase" reaction in the nose. In 7/17 subjects, a significant (P < 0.05) improvement of olfactory function after budesonide treatment was seen. In conclusion, topical steroid (budesonide) is superior to antihistamine (terfenadine) in treatment of nasal congestion in hay fever, especially for the postchallenge reaction, and may, in some cases, relieve the decreased sense of smell during pollen challenge.

Administration, Inhalation↗
PubMed1983

Biochemical studies of olfaction: binding specificity of odorants to a cilia preparation from rainbow trout olfactory rosettes.

Cilia isolated from the olfactory epithelium (olfactory rosettes) of rainbow trout (Salmo gairdneri) bind amino acids, which are odor stimuli to this species. We demonstrate that L-threonine, L-serine, and L-alanine bind to a common site, TSA, in the cilia preparation. All possible mixtures of two of the amino acids as competitors, with the third as the 3H-labeled ligand, were studied. The effect of two combined (unlabeled) competitors was always substantially less than additive compared with their actions singly. Along with additional inhibition studies using mixtures of inhibitors, the data show that the three odorants must interact with at least one common binding site, TSA. Binding of L-[3H]lysine to site L was unaffected by addition of L-threonine, L-serine, or L-alanine, establishing its independence from site TSA. L-Arginine inhibited binding of L-[3H]lysine, showing that both of these basic amino acids interact with site L. The data establish the presence, in trout olfactory cilia, of at least two separate and noninteracting populations of odorant binding sites, TSA and L.

Alanine↗
PubMed1980

Comparison of mucus collecting methods in fish olfaction.

A new method for collecting non-contaminated skin mucus from fishes is introduced. The method is compared with a "customary" method by gel filtration, analysis of free amino acids, and determination of dry weight. Skin mucus collected by the "customary" method is shown to be contaminated by intestinal juice. The role of skin mucus as a source of fish odorants affecting fish behaviour is discussed in the light of the above findings.

Amino Acids↗