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PubMed2003

Assessment of olfactory function and androstenone odor thresholds in humans with or without functional occlusion of the vomeronasal duct.

To obtain information on the possible role of the vomeronasal duct (VND) in odor perception and human pheromone detection, the present study investigated different aspects of olfactory function, including thresholds for androstenone in adults with or without detectable VNDs. The study also examined correlations between detection thresholds of androstenone odor and general olfactory function. Subjects' olfaction was assessed with tests for odor identification, odor discrimination, and phenyl ethyl alcohol odor threshold. Measurements were performed on 1 side only, with and without covering the VND. Subjects with or without detectable VNDs did not differ in olfactory sensitivity or androstenone odor thresholds. A small but significant correlation was found between detection thresholds of androstenone and general olfactory function. Finally, covering of the VND did not affect olfactory function or androstenone sensitivity. Results suggest that the human VND does not play a major role in sensitivity toward odorants or the perception of androstenone.

Adolescent↗
PubMed2001

Genetic tracing reveals a stereotyped sensory map in the olfactory cortex.

The olfactory system translates myriad chemical structures into diverse odour perceptions. To gain insight into how this is accomplished, we prepared mice that coexpressed a transneuronal tracer with only one of about 1,000 different odorant receptors. The tracer travelled from nasal neurons expressing that receptor to the olfactory bulb and then to the olfactory cortex, allowing visualization of cortical neurons that receive input from a particular odorant receptor. These studies revealed a stereotyped sensory map in the olfactory cortex in which signals from a particular receptor are targeted to specific clusters of neurons. Inputs from different receptors overlap spatially and could be combined in single neurons, potentially allowing for an integration of the components of an odorant's combinatorial receptor code. Signals from the same receptor are targeted to multiple olfactory cortical areas, permitting the parallel, and perhaps differential, processing of inputs from a single receptor before delivery to the neocortex and limbic system.

Animals↗
PubMed1980

Olfactory sensitivity in humans: genetic versus environmental control.

Olfactory sensitivity to acetic acid, isobutyric acid, and 2-sec-butyl-cyclohexanone was tested in 97 adult male twin pairs to determine the extent to which variation in odor perception was genetically determined. Analysis of the data revealed no evidence for heritability of olfactory sensitivity. However, factors significantly associated with odor perception included cigar, pipe, and cigarette smoking; body fatness; alcohol consumption; and diabetes mellitus.

Acetates↗
PubMed1990

Human odor intensity perception: correlation with frog epithelial adenylate cyclase activity and transepithelial voltage response.

Although a number of odorants are hypothesized to depolarize frog olfactory receptor cells by binding to ciliary glycoproteins which activate membrane-bound G-proteins to induce adenylate cyclase-mediated increases in intracellular cAMP (cyclic adenosine 3',5'-monophosphate), it is not known whether these odorants influence human odor perception via similar mechanisms. In this paper we present evidence derived from odor attribute ranking and multidimensional scaling procedures that the perceived intensity of such odorants to humans is correlated with (a) the amount of adenylate cyclase activity they induce in an in vitro frog olfactory cilia preparation and (b) the magnitude of their influence on the frog transepithelial voltage response or electro-olfactogram (EOG). These observations are in accord with the hypothesis that the perception of the intensity of some odors by humans is associated with cAMP-related epithelial processes and imply that remarkable homologies exist between the intensity-related olfactory receptor mechanisms of frog and man.

Adenylyl Cyclases↗
PubMed2004

Anesthesia affects olfaction and chemosensory event-related potentials.

OBJECTIVE: Olfactory and trigeminal systems interact and contribute to the perception of odorants. This study was aimed at investigating the effect of local anesthesia on olfaction. METHODS: One percent of tetracaine on a cotton swab was applied intranasally at three different locations in 20 volunteers and 4% of lidocaine was applied to the olfactory cleft in a head-down position. Before and after anesthesia, self-assessment, psychometric testing and olfactory event-related potentials [OERPs, using H(2)S and phenyl ethyl alcohol (PEA)], and chemosomatosensory event-related potentials (CSSERPs, using CO(2)) were examined. RESULTS: Anesthesia at all four locations significantly lowered the perceived self-assessment of olfaction, while using the cotton swab only anesthesia in the middle meatus elevated threshold (P = 0.020), lowered discrimination (P = 0.015), and prolonged OERP (PEA, P = 0.008; H(2)S, P = 0.016), as well as CSSERPs latencies (CO(2), P = 0.020). However, complete temporary anosmia was only achieved after applying 4% lidocaine into the olfactory cleft. CONCLUSIONS: Intranasal anesthesia applied with a swab reduced self-assessment of olfaction but was unable to produce anosmia. Psychometric test results were concordant with changes in chemosensory event-related potentials. SIGNIFICANCE: Temporary anosmia is technically difficult to achieve but could be demonstrated for the first time using local anesthesia. Even though anesthesia influences self-assessment, measurable olfactory function can remain unchanged.

Administration, Intranasal↗
PubMed1993

Discriminating parts from the whole: determinants of odor mixture perception in squirrel monkeys, Saimiri sciureus.

In a task designed to simulate olfactory-guided foraging, the ability of squirrel monkeys to discriminate an artificial 12-component odorant from 3-, 6-, 9- or 11-component submixtures was investigated. A combination of factors was found to contribute to the animals' performance: 1. Discriminability generally decreased as the number of components in the submixture increased. 2. Submixtures did not contribute equally to mixture perception, and one component in particular (cineole) disproportionately influenced stimulus discriminability. 3. Interactive effects between submixtures resulted in marked deviations from the general pattern of discriminability. 4. Changes in the relative concentration of submixtures could also influence discriminability. 5. Finally, individual differences in responsiveness to particular stimuli were apparent. These findings demonstrate that the interaction between components in odor mixtures can be complex and that seemingly small changes in composition can strongly affect perception and thus potential signal function. It is therefore suggested that in future investigations of squirrel monkey semiochemistry, the method of systematically varying submixtures may be particularly useful in defining the contribution of components to a signal.

Adult↗
PubMed2001

Sensing scenes with silicon.

Scene analysis, the process of converting sensory information from peripheral receptors into a representation of objects in the external world, is central to our human experience of perception. Through our efforts to design systems for object recognition and for robot navigation, we have come to appreciate that a number of common themes apply across the sensory modalities of vision, audition, and olfaction; and many apply across species ranging from invertebrates to mammals. These themes include the need for adaptation in the periphery and trade-offs between selectivity for frequency or molecular structure with resolution in time or space. In addition, neural mechanisms involving coincidence detection are found in many different subsystems that appear to implement cross-correlation or autocorrelation computations.

Animals↗
PubMed2004

[Olfactory function and olfactory marker protein in patients with chronic sinusitis].

OBJECTIVE: To study the pathogenesis of dysosphresia in patients with chronic sinusitis, to discuss the expression and significance of olfaction marker protein in olfactory mucosa. METHODS: There were 55 cases with chronic sinusitis in the experimental group, and 11 cases in the control. All of them were first tested by subjective method, and then the olfactory marker protein in olfactory mucosa was examined by the method of immunohistochemistry. Tissue sections were observed under optical microscope. RESULTS: The ratio of dysosphresia in patients with chronic sinusitis was 50.9% (28/55), while by subjective olfactory test, it was 85.5% (47/55). The ratio of dysosphresia in control patients was 9.09% (1/11), by subjective olfactory test, it was 18.2% (2/11). Olfactory marker protein was identified in the olfactory cells and microvillar cells by histochemical and immunohistochemical technique (S-P method). CONCLUSIONS: The main cause of dysosphresia in patients with chronic sinusitis is the decrease, atrophy and degeneration of the olfactory cells, which lead to the failure of olfactus perception and recognition.

Adolescent↗
PubMed1999

Deterioration of olfaction and gustation as a consequence of total laryngectomy.

INTRODUCTION: After total laryngectomy the absence of a nasal airflow results in a decrease in olfaction and perception of flavors. MATERIALS AND METHODS: Odor perception was assessed in 63 laryngectomized patients with two different olfactory tests. The methods used by patients to smell were observed during olfactory testing. Patients' judgment about their olfaction and gustation was assessed by means of a structured questionnaire, semistructured interview, and self-rating. RESULTS: Based on the results of the olfactory tests, patients were categorized as "smellers" and "nonsmellers." Approximately one third of the patients were able to smell the odorous substances used in the olfactory tests. The smellers more often used a variety of methods to smell than the nonsmellers (P < .002); in most patients the method consisted of active use of facial muscles. Patients appeared well able to judge their own odor perception. Compared with the smellers, the nonsmellers judged their odor perception as worse (P < .003) and reported a more severe decrease in gustation after the operation (P < .033). The results of this study in laryngectomized patients confirm the interrelation between olfaction and gustation: the nonsmellers reported a poorer gustation and a more severe decrease in gustation and appetite than both the smellers and a reference group of elderly persons (P < .05). Patients who reported a deterioration of olfaction and gustation tended to experience negative consequences such as the inability to smell smoke, leaking gas, or agreeable odors. CONCLUSION: Olfaction and odor-related flavor sensation are seriously deteriorated after total laryngectomy.

Aged↗
PubMed2001

Enantioselectivity of odor perception in honeybees (Apis mellifera carnica).

The authors tested the ability of 60 free-flying honeybees (Apis mellifera carnica) to discriminate a conditioning odor from an array of 26 simultaneously presented substances. The stimuli included 10 pairs of enantiomers and 6 essential oils. The bees (a) significantly distinguished between 98% of the 540 odor pairs tested, thus showing an excellent overall discrimination performance, and (b) were able to discriminate between the optical isomers of limonene, alpha-pinene, beta-citronellol, menthol, and carvone but failed to distinguish between the (+)- and (-)-forms of alpha-terpineol, camphor, rose oxide, fenchone, and 2-butanol. The findings support the assumptions that enantioselective molecular odor receptors may exist only for some volatile enantiomers and that insects and mammals may share common principles of odor quality perception, irrespective of their completely differing repertoires of olfactory receptors.

Animals↗
PubMed1976

Perceptual factors in the design of environments for the mentally ill.

Administrators and others responsible for the design of environments for the mentally ill must be aware that what might be considered irrelevant minutiae of design can have traumatic effects on patients. Because of patients' heightened sensitivity to sensory stimuli and their lessened ability to filter out or adjust to the effects of such stimuli, they are much more likely to be affected by their surroundings than are healthier people, and their social relationships are correspondingly affected. The author describes several kinds of visual, auditory, olfactory, and other stimuli that lead to distorted perceptions of oneself and others and of time and space. He recommends not a bland and stimulus-free environment, but one whose elements are unobtrusive and unambiguous.

Environment Design↗
PubMed2001

Effect of nasal dilators on nasal structures, sniffing strategies, and olfactory ability.

This paper describes the effects that nasal dilators have on olfactory ability. Experimental results demonstrate that nasal dilators increase odorant identification, lower odorant threshold, and increase perceptual odorant intensity. In other experiments, magnetic resonance imaging (MRI) data demonstrates that the size of the nasal cavity especially around the region of the nasal valve is increased when nasal dilators are worn. Additionally, pneumotachograph data demonstrates that during a sniff, the peak flow, maximum flow rate, volume, and duration are all increased when nasal dilators are worn. Taken together, the increase in olfactory ability can most easily be explained by an increase in both the amount and the proportion of inspired odorant molecules that are directed to the olfactory mucosa and are, therefore, available for odorant perception.

Adult↗
PubMed1991

Functional subdivisions of the olfactory system correlate with lectin-binding properties in Xenopus.

Soybean agglutinin (SBA) is known to selectively label a portion of neurons in amphibian and mammalian primary olfactory systems. Hitherto, no other distinctive features have been found to correlate with the two neuronal populations. Investigating SBA-HRP binding in olfactory mucosa and CNS of Xenopus, we noted that labelled and unlabelled structures can readily be assigned to different olfactory subsystems. The SBA negative one is utilized to detect air-borne odors, whereas major SBA-positive structures serve a role in the perception of water dissolved molecules. Some labelled fibers by-pass the olfactory bulb, traverse the telencephalon and innervate prosencephalic structures. They are considered to be aberrant olfactory nerve fibers, rather than being part of the terminal nerve.

Animals↗
PubMed1986

Multimodal sensory discrimination deficits in Korsakoff's psychosis.

A consistent impairment in odor identification was observed among a group of 21 amnesic patients, diagnosed as having Korsakoff's psychosis. In a subsequent study of eight Korsakoff and matched alcoholic control subjects, a comparable olfactory deficit was again demonstrated, as well as impairment in color discrimination and auditory perception. No such deficit was observed for a picture identification task designed to control for the non-sensory demands of the olfactory test. Stepwise multiple regression analysis showed a significant correlation between odor identification scores and the concentration of the primary metabolite of norepinephrine in lumbar cerebrospinal fluid. The data demonstrate a consistent coincidence between memory impairment and deficient sensory perception among patients with Korsakoff's psychosis.

Adult↗
PubMed1995

Responses recorded from the frog olfactory epithelium after stimulation with R(+)- and S(-)-nicotine.

The aim of this study was to determine whether the olfactory system is responsible for the discriminability of the stereoisomers of nicotine. The EOG was recorded after stimulation with different concentrations of undistilled S(-)-, distilled S(-)- and distilled R(-)-nicotine separately in three groups of frogs (Xenopus laevis). The responses to all types of nicotine used in the experiments increased with increasing stimulus concentration. The responses to undistilled S(-)-nicotine were significantly lower compared to responses to distilled S(-)- and R(+)-nicotine, whereas no significant differences could be found when the purified stereoisomers of nicotine [distilled S(-)-nicotine, distilled R(+)-nicotine] were compared. Control measurements of time course and peak concentration employing a UV-detection method demonstrated that the differences between distilled and undistilled S(-)-nicotine could not be explained by different nicotine concentrations. The fact that no differences between the pure nicotine stereoisomers could be found for all concentrations used in our experiments and that experiments in humans revealed similar detection thresholds for both stereoisomers points to a similar receptor affinity of R(+)- and S(-)-nicotine within the olfactory system. At this point, it cannot be determined whether the observed differences in the perception of nicotine enantiomers in humans are due to differences in quality coding by stereospecific receptors on the olfactory sensory cells or by specific receptors on the trigeminal nerve endings.

Animals↗
PubMed1981

[Olfactory stimulation and contingent negative variation (CNV) (author's transl)].

In addition to olfactory evoked responses (Fig. 1a) the vertex-negative voltage shift was registered in 20 normal adults. Fig. 2 shows this potential for an olfactory indicative stimulus followed by a tone burst or flash sequence, which are stopped by the test person's manual reaction. In Fig. 3 two alternating odorous stimuli are presented, one of which is followed by the tone. The selective expectancy wave is followed by the tone. The selective expectancy wave is only built up by the marked olfactory stimulus. For the first time CNV can be used as a clinical investigation tool to confirm central perception of odorous stimuli and furthermore to objectivate impaired central odour discrimination (parosmia).

Adult↗
PubMed2006

Comparison of subjective perception with objective measurement of olfaction.

OBJECTIVE: To see if nasal peak inspiratory flow rate and subjective sense of smell had any correlation with olfactory thresholds. STUDY DESIGN AND SETTING: A cohort study of 186 normal volunteers was recruited from among staff and visitors at a university hospital. Olfactory thresholds were detected for each subject (103 with eucalyptol and 83 with phenethyl alcohol), along with nasal peak inspiratory flow (PIFR). Subjective sense of smell, along with nasal symptoms, mood, and alertness, were recorded on visual analogue scores. RESULTS: Subjective perception of smell had no correlation with olfactory thresholds detected (P = 0.4057) and the other subjective measures also had no correlation. There was a significant relationship of PIFR to thresholds in the group tested with phenethyl alcohol (P = 0.002). CONCLUSION: As with the sensation of nasal patency, the self-assessment of a subject's sense of smell has poor correlation with their actual olfactory ability. SIGNIFICANCE: A patient's history cannot be relied upon when determining their olfactory ability and formal testing should be performed. EBM RATING: A-1b.

Adolescent↗