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At least 541 records · Page 30Linked to original sources
PubMed1989

Identification of self through olfaction.

To study olfactory communication in humans, 100 undergraduates ranging from age 18 to 45 yr. wore freshly washed, identical T-shirts continuously for 24 hr. During this time, the participants did not bathe or shower or apply any scent producing substance to their bodies, i.e., deodorants, perfumes. Upon retrieval, each shirt was placed in an identical brown bag. In groups of 10, each participant attempted to identify the T-shirt he had worn the previous 24 hr. The task was administered separately for each individual so that no participants knew the choice by a previous colleague. Analysis shows that the participants were able to identify correctly their own shirts on the first try three-quarters of the time. Furthermore, sex, age, smoking habit of the participant, and menstrual cycle phase in the women were factors in successful outcomes.

Adolescent↗
PubMed2000

Geko, a novel gene involved in olfaction in Drosophila melanogaster.

To characterize genes involved in olfactory responses to chemical attractants, we screened 3000 P-element-tagged lines for their attraction to ethanol. Ten lines showed reduced levels of response, and revertants of these lines were obtained by excising the inserted P-element. The olfactory response of one line reverted to wild-type behavior compared to the original mutant line. The gene affected by this P-lacW insertion was named geko (gk). A 1.3-kb transcript was found to emanate from close to the P-insertion site, and the 5' upstream region was interrupted by the P-element. The amount of mRNA of gk gene in the P-lacW inserted line was about half that of the control strain. The response to ethanol of the gk(1) mutant was restored by transforming the genomic region containing this transcription unit. lacZ expression (stemming from this reporter-gene's presence in the transposon) was observed in the antenna and the antennal-maxillary complex (the olfactory organ of adults and larvae, respectively). gk mRNA was detected at the antenna and from other parts of the body. The deduced gk product showed no overall similarity to any reported amino-acid sequences.

Animals↗
PubMed1992

The rdgB gene of Drosophila: a link between vision and olfaction.

ota1 (ota = olfactory trap abnormal), an X-linked mutation of Drosophila isolated by virtue of abnormal olfactory behavior, is shown to be an allele of rdgB (retinal degeneration B), a gene required for normal visual system physiology. rdgB function is shown to be necessary for olfactory response of both adult flies and larvae, which have distinct olfactory systems. Electrophysiological recordings from the adult antenna indicate that rdgB is required for normal response in the peripheral olfactory system: some rdgB mutants show a delayed return to the resting potential following stimulation with ethyl acetate vapor. These results indicate that rdgB is required for both visual and olfactory physiology, and they suggest that visual and olfactory transduction may share at least one common molecular step in Drosophila.

Alleles↗
PubMed2001

Olfaction in elderly and patients with Alzheimer's disease: Differing feedback conditions.

Objective: To determine the capability of patients with Alzheimer's disease (AD) and age-matched controls to discriminate and recognize odorants equilibrated for strength and familiarity, and to determine if immediate corrective-feedback can improve performance in either task. Major results: No significant differences between elderly controls (EC) and AD patients were apparent for the discrimination task regardless of feedback condition. The EC group outperformed the AD group on the recognition task. Feedback enhanced EC group performance but failed to benefit the AD group. Conclusions: Early in the disease process, AD subjects have a deficit in processing olfactory cues at levels beyond that necessary for discrimination. This deficit is specifically related to the olfactory system and is in addition to any general cognitive deficits they may have. Feedback is ineffective for AD subjects but can greatly enhance the performance of the intact elderly on tasks requiring the verbal mediation of olfactory cues.

Journal Article↗
PubMed1999

A computer-controlled olfactometer for fMRI and electrophysiological studies of olfaction.

A design for an inexpensive and reliable olfactometer is presented. The design has several advantages for fMRI and electrophysiology investigators. These advantages include relatively rapid odorant rise times, computer control, multiple odor administration, and no ferrous materials near the subjects. In addition, the device is contamination resistant, and, because the air is neither warmed nor humidified, it is unlikely to become an incubator for bacteria. The olfactometer is constructed of off-the-shelf chromatography parts that require little modification.

Computers↗
PubMed1976

Olfaction and the common chemical sense: some psychophysical contrasts.

Three experiments explored the olfactory and the common chemical attributes of sensations produced by various concentrations of n-butyl alcohol. These two attributes combine in an almost-linear fashion to produce the overall perceived intensity of the stimulus. Common chemical intensity makes only a small contribution to overall magnitude at low concentrations, but its proportional contribution increases with concentration. In like manner, speed of response (i.e., reciprocal of reaction time) to the common chemical attribute increases more rapidly than that to odor. Nevertheless, odor always makes its appearance sooner than the common chemical attribute, even when the two attributes are matched in perceived magnitude. Repeated inhalations cause odor intensity to decrease slightly but cause common chemical intensity to increase dramatically. The results obtained from the normal subjects studied here agree with those obtained from subjects with unilateral destruction of the trigeminal nerve.

Butanols↗
PubMed2000

Coding principles in fish olfaction as revealed by single unit, EOG and behavioral studies.

At present, the principles of coding and codes for individual odorants are not known; however, several coding properties and their limitations emerged. The olfactory code for different odorants must be different to enable olfactory discrimination. We studied elements of the olfactory code that are accessible to combined microelectrode and behavioral techniques. A random sample of spontaneously active olfactory receptor neurons (ORNs) responded to a 15 component mixture of amino acids with suppression, excitation and no change in their activity in the ratio of 6:1:8; ORNs responded to L-arginine (L-Arg) in the ratio of 5:5:60 and to L-cysteine (L-Cys) in the ratio of 10:1:27. ORNs provide information that enables nearly an unlimited behavioral discrimination of single odorants. Underwater electro-olfactogram (EOG) recordings from the olfactory organ measure the odorant-induced summed dc potential change from all the olfactory receptor neurons. In behavioral studies, the more (most) stimulatory component of the binary (ternary) mixture determined in EOG recordings was its better-perceived component; however, discrimination conditioning--repeated presentation of the conditioned mixture and its more stimulatory component alone--enabled the discrimination of the conditioned binary and ternary mixtures from their more (most) stimulatory components. In large multimixtures (13 components), where one amino acid is the more potent EOG stimulus than the other less stimulatory but equipotent components, catfish discriminated all single components from the conditioned multimixture. These results indicate that the multi-mixture is not detected as its most stimulatory component. Catfish also do not learn to discriminate a 13 component multimixture from a 12 component multimixture comprising 12 of the same components. Taken together, these findings indicate that the capacity for parallel transfer of mixture component information is limited in the catfish olfactory system. The finding of a limited capacity of multimixture component detection in catfish also supports the hypothesis of across nerve pattern coding of odorants and eliminates the sole existence of entirely specialized olfactory receptor neurons and labeled lines.

Amino Acids↗