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A possible relationship between odor perception and introversion-extraversion was explored. 195 subjects completed Eysenck's Introversion-Extraversion Scale and rated strength, familiarity, and pleasantness of four odors. Zero-order correlations were examined and the data were factor analyzed. The introversion-extraversion items formed a factor separate from three olfactory factors.
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The behavior of mole rats (Spalax ehrenbergi) near pairs of enantiomeric compounds was examined in 901 two-choice experimental tests. Positioning of the nest and food store and the preferred location of the tested animal were used to assess attraction or aversion to the tested odorants. The results indicated that mole rats respond differentially to odors of stereoisomers (enantiomers of carvone, citronellol, and fechone). They responded to one enantiomer of each tested pair but were indifferent to or did not smell the other. Both sexes were attracted to the odor of R-(-)-carvone and repelled by the odor of (+)-citronellol. Females were attracted to the odor of (-)-fenchone while males had no preference. By contrast, all animals were indifferent to or did not smell the odor of S-(+)-carvone, (-)-citronellol, and (+)-fenchone. Further research to distinguish between these alternatives (indifference vs hyposmia/anosmia) is suggested.
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We investigated the processing of odorant mixtures containing two to seven components by the spiny lobster Panulirus argus. The chemicals tested were food-related compounds that are attractive to spiny lobsters, and include adenosine-5'-monophosphate, betaine, L-cysteine, L-glutamate, DL-succinate, taurine, and ammonium. Components were tested at concentrations that produced search behavioral responses of equal magnitude in unconditioned animals. Responses of unconditioned animals to mixtures and their components reveal hypoadditivity, in which the response to a mixture is less than the sum of the responses to that mixture's components. Aversive conditioning coupled with generalization testing was used to evaluate generalization and hence perceptual similarity between related mixtures. Animals were conditioned to either an individual odorant, a four-compound mixture, or a seven-compound mixture, followed by generalization testing with submixtures or larger mixtures containing the conditioned stimulus. Animals tended not to generalize, but significant generalization between a more simple conditioned stimulus and more complex mixtures containing that conditioned stimulus occurred in 2 of 11 cases, and significant generalization between a conditioned mixture and its submixtures was observed in 4 of 9 cases. Both the number and chemical identity of components of mixtures may contribute to the degree of generalization between mixtures. Overshadowing, in which the ability to learn about a chemical is affected by simultaneous presentation of other chemicals, occurred in two of three cases. We discuss implications of these findings with respect to elemental and configural processing of odorant mixtures in the spiny lobster, possible neural mechanisms responsible for these results, and the potential utility of generalization and overshadowing to the spiny lobster's natural behavior.
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p-Chlorophenylalanine treatment eliminated the normal male rat preference for the female preputial gland odor. Oral administration of hydrocortisone had a similar effect on dimethyl sulfite preference, which slowly reappeared after the discontinuance of the treatment. These changes of behavior are discussed in relation to possible serotonin alterations resulting from the treatments.
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Odor and olfaction anthropology explores four lines of research which, in many cases, may overlap: the variability of the olfactory perception, olfactory skills and know-how, odor use, and odor representations. My proposal here is to deal with the first one, trying to answer the following question: is olfactory perception a phenomenon resulting solely from the biological organization of the human being, in such a way that it does not know other variations than the ones due to nature? Or, on the contrary, can we show different kinds of olfaction culturally determined or, at least, environmental influences resulting in significant perceptual differences among groups, societies, cultures, etc.? In the first part of the text, I will deal with the invariants (or universals). In the second, I will insist on the cultural types of olfaction. In the third and last part, I will advance the following proposal: beyond the discussion on the roles that nature and culture play in human olfaction, we can sustain that naturally and culturally, there is a way of smelling characteristic of our species. Finally, I will conclude with two examples of the symbolic treatment characteristic of the olfactory human experience.
The authors tested suprathreshold intensity perception of gustatory and olfactory stimuli in a 70-year-old right-handed man following a left posterior insular stroke and compared his results with those of age-matched controls. Both modalities revealed significant differences between left (ipsilateral to lesion) and right (contralateral) ratings of intensity. In both gustation and olfaction, these differences were driven primarily by trends toward increased contralateral sensitivity relative to controls. Intensity changes were most pronounced for unpleasant odors and for tastes perceived strongly as either pleasant (sweet) or unpleasant (salty, bitter). These results show that a left posterior insula lesion may affect taste and olfactory perception similarly by increasing sensitivity contralateral to the lesion. One possible mechanism is release from inhibition at the cortical level.
Young adult Long-Evans female rats were subjected to intracerebroventricular injections of 150 microg 5,7-dihydroxytryptamine (5,7-DHT), 2 microg 192 IgG-saporin, or a combination of both neurotoxins. All rats were tested for olfactory recognition (short-term memory) using a task based on spontaneous exploration of odor sources. Compared with animals undergoing sham operations, 5,7-DHT reduced the concentration of serotonin by 60-80% in the frontoparietal cortex, hippocampus, striatum and the olfactory bulbs. After 192 IgG-saporin treatment, acetylcholine concentrations were reduced by approximately 40% in all these structures, except the striatum. Neither lesion induced a significant deficit in olfactory recognition. These data suggest that combined lesions of cholinergic and serotonergic neurons in the rat brain do not alter olfactory perception or olfactory short-term memory.
A case of phantom smelling (phantosmia) is described in a 28-yr.-old man who developed permanent bilateral anosmia after a serious injury to olfaction-related brain structures at the age of 25 years. The findings indicate that, even years after loss of input from olfactory receptors, the neural representation of olfactory perception can still recreate olfactory sensations without any conscious recall of them. This indicates that the neural representation of olfactory sensations remains functional and implies that neuronal activity in the olfactory organ or in other brain structures gives rise to olfactory experiences perceived as originating from the perception of original odor substances. The report suggests the intriguing possibility that the olfactory perception is not a passive process that merely reflects its normal input from the olfactory system but is continuously generated by a neural representation in the olfactory organ or in other olfaction-related brain structures, based on both genetic and sensory determinants. To the author's knowledge this is the first reported case of its kind.
OBJECTIVE/DESIGN: To determine the nutritional risk associated with measured olfactory dysfunction in free-living, elderly women through analytic observational methods. Olfactory perception was measured orthonasally (odor: butanol threshold and odor identification) and retronasally (flavor: orange flavor threshold in sweetened gelatin). SETTING/SUBJECTS: Elderly women were recruited from New Haven, Conn, through posters and direct contact. Screening of 120 elderly women identified 80 with high personal functioning to participate (mean age = 76 +/- 6 years, range = 65 to 93 years). All data were collected in subjects' homes. MAIN OUTCOME MEASURES: Nutritional risk was assessed in several ways: food behavior questionnaire; food preference questionnaire; interviews based on the National Cancer Institute food frequency questionnaire; five nonconsecutive, 24-hour food records; and weight, height, waist, and hip measurements. STATISTICAL ANALYSES: Correlation and regression analyses determined the separate association between olfactory perception and nutrition variables. RESULTS: Nearly half of the women (37 of 80) had olfactory dysfunction. The following nutritional risk pattern was associated with lower olfactory perception: lower interest in food-related activities (eg, enjoying cooking, eating a wide variety of foods); lower preference for foods with predominant sour/bitter taste (eg, citrus fruits) or pungency (eg, horseradish); higher intake of sweets; less intake of low-fat milk products; and nutrient intake profile indicative of higher risk for cardiac disease. APPLICATIONS: Olfactory dysfunction may make it more difficult for elderly women to maintain a diet to control risk for chronic disease. Practitioners should target nutrition intervention to elderly women with measured or self rated difficulty in preventing odors or olfactory flavor. Capitalizing on primary-taste quality and texture may help to compensate for the loss of olfactory flavor perception.
BACKGROUND: Olfaction has obvious correlates with emotional processes but little is known about the several aspects of olfaction in psychiatric disorders characterized by mood disturbance. This research aims at pointing out the specificities of olfactory perception in patients in order to identify the specific cerebral impairments involved in these disorders. METHODS: Olfactory sensitivity, detection, identification, self-evaluation of intensity and pleasantness have been recorded in a control group of healthy subjects (N = 58) and in three sample populations admitted to a Psychiatry Department: depressive patients (N = 49), anorectic patients (N = 17), and patients suffering from addiction to alcohol or drugs (N = 21). RESULTS: Depressive patients have a poor sensitivity, poor detection abilities but over-evaluate the pleasantness of odors. Anorectic patients have a high sensitivity, over-evaluate the intensities of the odors but under-evaluate their pleasantness. Alcoholic/drug addicted patients showed impairments in identification. LIMITATION: This study does not identify inter-individual differences in olfactory perception. CONCLUSION: The psychiatric diseases, here at hand although every one of them may be characterized by depressive components, show diverging impairments in olfactory perception. When variations in sensitivity are usually attributed to peripheral cues, impairments in emotional and cognitive aspects of olfaction are typically related to specific brain structures and processes which could be particularly involved in these diseases.
Odorant-binding proteins (OBPs) represent a highly abundant class of proteins secreted in the nasal mucus by the olfactory neuroepithelium. These proteins display binding affinity for a variety of odorant molecules, thereby assuming the role of carrier during olfactory perception. However, no specific interaction between OBP and olfactory receptors (ORs) has yet been shown and early events in olfaction remain so far poorly understood at a molecular level. Two human ORs, OR 17-209 and OR 17-210, were fused to a Green Fluorescent Protein and stably expressed in COS-7 cell lines. Interaction with OBP was investigated using a highly purified radioiodinated porcine OBP (pOBP) preparation, devoid of any ligand in its binding cavity. No specific binding of the pOBP tracer could be detected with OR 17-209. In contrast, OR 17-210 exhibited specific saturable binding (K(d) = 9.48 nM) corresponding to the presence of a single class of high-affinity binding sites (B(max) = 65.8 fmol/mg prot). Association and dissociation kinetics further confirmed high-affinity interaction between pOBP and OR 17-210. Autoradiographic studies of labeled pOBP to newborn mouse slices revealed the presence of multiple specific binding sites located mainly in olfactory tissue but also in several other peripheral tissues. Our data thus demonstrate a high-affinity interaction between OBP and OR, indicating that under physiological conditions, ORs may be specifically associated with an OBP partner in the absence of odorant. This provides further evidence of a novel role for OBP in the mechanism of olfactory perception.
Based on previous research it may be hypothesized that the perception of odorants is modified by an axon reflex emanating from trigeminal afferents activated via the skin and/or the intranasal respiratory epithelium. The present experiment investigated the effects of trigeminal cutaneous stimulation on intensity estimates of intranasal chemical stimuli. While the left nostril was stimulated chemically with olfactory and trigeminal stimulants, four regions of the face were stimulated electrically. Intensity estimates of the chemical stimuli tended to increase after cutaneous electrical stimulation which may be interpreted in terms of response priming. The effect of electrical stimulation did not differ at the 4 stimulation sites. The results argue against the hypothesis that the processing of intranasal chemical stimuli is modified peripherally by cutaneous trigeminal excitation.
Several lines of studies have reported that olfactory perception is influenced by physical and hormonal conditions. In the present study, we investigated changes of olfactory perception during the menstrual cycle of the human. Cyclopentadecanolide vapor was used and its perception intensity was measured by 6-point category scale methods. We especially focused on a novel concept termed "olfactory contrast" that has been just very recently derived from the patch clamp experiment that uses the solitary olfactory receptor cell. The results obtained from 18 trials (15 subjects) showed that olfactory contrast was significantly enhanced at the ovulatory and/or menstrual phases. It is suggested that olfactory contrast, which we defined as a new parameter, provides a useful tool in many kinds of studies exploring the olfactory perceived ability.