Olfactory Conditioning of Positive Performance in Humans

Crossmodal Interactions Between Olfaction and Touch Affecting Well-Being and Perception of Cosmetic Creams

In the present series of studies, we investigated crossmodal perception of odor and texture. In four studies, participants tried two textures of face creams, one high viscosity (HV) and one low viscosity (LV), each with one of three levels of added odor (standard level, half of standard, or base [no added odor]), and then reported their levels of well-being. They also reported their perceptions of the face creams, including liking (global liking of the product, liking of its texture) and “objective” evaluations on just about right (JAR) scales (texture and visual appearance evaluations). In Study 1, women in France tried the creams on their hands, as they would when testing them in a store, and in Study 2, a second group of French women tried the creams on their faces, as they would at home. In Studies 3 and 4, these same two procedures were repeated in China. Results showed that both odor and texture had effects on well-being, liking, and JAR ratings, including interaction effects. Though effects varied by country and context (hand or face), the addition of odor to the creams generally increased reports of well-being, global liking and texture liking, in some cases affecting the “objective” evaluations of texture. This is one of the first investigations of crossmodal olfactory and tactile perception's impacts on well-being, and it reinforces previous literature showing the importance of olfaction on well-being.

The Rewarding Effect of Pictures with Positive Emotional Connotation upon Perception and Processing of Pleasant Odors-An FMRI Study

This fMRI study was designed to investigate the effect of cross-modal conditioning in 28 female volunteers. Subjects underwent initial fMRI block design scanning during which three pleasant olfactory stimuli were presented and had to be rated with respect to intensity and pleasantness. This was followed by an odor identification task spread out over 3 days: the experimental group was rewarded for successful trials (correct odor identification) with emotionally salient photos, whilst the control group only received randomly displayed, emotionally neutral, pictures. In the final scanning session, the odors were again presented, and subjects rated pleasantness and intensity. Both pleasantness ratings and fMRI data showed effects of the rewarding procedure. Activation in nucleus accumbens and the orbitofrontal cortex confirmed the hypothesis that learnt association of odors with visual stimuli of emotionally positive valence not only increases pleasantness of the olfactory stimuli but is also reflected in the activation of brain structures relevant for hedonic and reward processing. To our knowledge, this is the first paper to report successful cross-modal conditioning of olfactory stimuli with visual clues.

[Olfaction in depressive disorders: Issues and perspectives]

Research on sensorial interactions with psychiatric diseases and particularly with the depressive syndrome has mainly focused on visual or auditory processes and much less on olfaction. The depressive illness is one of the most frequent psychiatric diagnoses in the community, with approximately one in five women and one in eight men experiencing a major depressive episode during their lifetime. Although genetic, epigenetic, neuroanatomical, neurochemical, neuroendocrinological and neuroimmunological changes can be detected during depression, the etiology of depression remains partly unclear. The current explanatory models are based on two main factors, i.e. pharmacological dysfunctions and stress effects. In this way and because of strong connections between olfactory pathways and cerebral areas implied in mood regulation and emotions (i.e. the limbic system and prefrontal areas), the interactions between olfaction and depression could constitute a relevant way of research at three different levels. First, olfactory dysfunction observed in depression could serve the diagnosis and contribute to a better understanding of mechanisms implied in thymic pathologies. Published papers show a decrease of olfactory sensitivity in major depression which does not occur in bipolar or saisonal depression. Second, it has been shown that olfactory deficits could induce depressive symptoms. In this context, an animal model (olfactory bulbectomized rat) reinforces the hypothesis of the important role of olfaction in depression based on neuroanatomical and neurochemical observations. Third, several publications have demonstrated that odors can positively impact the depressive mood. Thus, a remediation by odors in depression appears to be a promising way. From several decades, the olfaction/depression interactions have been covered by a broad literature. Thus, the present review will not propose an exhaustive examination but aims to point out the most recently published papers and highlight their contributions to the understanding of olfactory processes implied in depression.

Pleasantness of the odor of androstenone as a function of sexual intercourse experience in women and men

Androstenone (5α-androst-16-en-3-one) and other androstenes, body odor components occurring in apocrine secretions, may play a role in human chemosignaling. We hypothesized that the odor of androstenone may gain hedonic value from sexual intercourse experiences via associative learning. Young adults (N = 397, 61.5% women, age 21-24 years, randomly sampled regarding sexual experience) rated the intensity and pleasantness of the odors of androstenone, cinnamon, chocolate, isovaleric acid, lemon, and turpentine. Among women who were able to perceive androstenone, the odor was rated as more pleasant (less unpleasant) by those who had had experienced sexual intercourse with at least one partner (n = 175) than by those who reported never having experienced intercourse (n = 12, p = .006). The difference was specific to women. The results suggest that, among women, sexual experience may modify the pleasantness of the odor of androstenone.

Indoor air pollutants in office environments: assessment of comfort, health, and performance

Concentrations of volatile organic compounds (VOCs) in office environments are generally too low to cause sensory irritation in the eyes and airways on the basis of estimated thresholds for sensory irritation. Furthermore, effects in the lungs, e.g. inflammatory effects, have not been substantiated at indoor relevant concentrations. Some VOCs, including formaldehyde, in combination may under certain environmental and occupational conditions result in reported sensory irritation. The odour thresholds of several VOCs are low enough to influence the perceived air quality that result in a number of acute effects from reported sensory irritation in eyes and airways and deterioration of performance. The odour perception (air quality) depends on a number of factors that may influence the odour impact. There is neither clear indication that office dust particles may cause sensory effects, even not particles spiked with glucans, aldehydes or phthalates, nor lung effects; some inflammatory effects may be observed among asthmatics. Ozone-initiated terpene reaction products may be of concern in ozone-enriched environments (≥0.1mg/m(3)) and elevated limonene concentrations, partly due to the production of formaldehyde. Ambient particles may cause cardio-pulmonary effects, especially in susceptible people (e.g. elderly and sick people); even, short-term effects, e.g. from traffic emission and candle smoke may possibly have modulating and delayed effects on the heart, but otherwise adverse effects in the airways and lung functions have not been observed. Secondary organic aerosols generated in indoor ozone-initiated terpene reactions appear not to cause adverse effects in the airways; rather the gaseous products are relevant. Combined exposure to particles and ozone may evoke effects in subgroups of asthmatics. Based on an analysis of thresholds for odour and sensory irritation selected compounds are recommended for measurements to assess the indoor air quality and to minimize reports of irritation symptoms, deteriorated performance, and cardiovascular and pulmonary effects.