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Background: Desensitization in response to repetitive odorous stimulations is a common and well‐investigated process, but it has been a matter of discussion in which way this process relates to odor valence. Our goal was to investigate changes of intensity and pleasantness induced by desensitization in odors in relation to their valence and concentration. Materials and Methods: Using air‐dilution olfactometry, 30 normosmic participants received two pleasant (phenylethylalcohol [PEA], mixture of pleasant odorants [mix‐P]) and two unpleasant odors (hydrogen sulfide [H2S], mixture of unpleasant odorants [mix‐NP]). At the baseline (before desensitization), four different concentrations of each odor were presented randomly for 0.2 s, with 40 s inter‐stimulus interval. During the desensitization procedure, the odor used was presented continuously for 15 s. Following an odor‐free interval of 4 s the same odor was presented again, in the post‐desensitization phase. Odor intensity and pleasantness were rated after presenting each stimulus in pre and post desensitization phases. Results: At baseline, Mix‐P was rated as pleasant and H2S was rated as unpleasant, as expected, while PEA and mix‐NP were rated as slightly pleasant or neutral, respectively. For intensity, desensitization was found for all odors regardless of hedonic tone, with the effect being more pronounced with PEA and mix‐NP at lower concentrations. A decrease of pleasantness/unpleasantness ("affective habituation") was present for the two lower concentrations of the pleasant mixture, while hedonic ratings of the unpleasant odors remained largely unchanged. Conclusions: These results suggest that, in this model, desensitization in intensity between pleasant and unpleasant odors was similar and affective habituation only occurred for the most pleasant odor. Practical Applications: Our study unraveled the link between odor desensitization and valence considering the concentration effect, where the intensity was decreased for the relatively "neutral" odors and pleasantness was habituated only for the pleasant odor. These results help to explain individual differences in the effects of olfactory loss and provide a promising perspective for personalized treatment for olfactory loss in clinics, for instance, fast adaptation and parosmia. [ABSTRACT FROM AUTHOR]

Odorants in food or beverages might enhance the taste. This phenomenon is called Odor‐Induced Taste Enhancement (OITE). OITE has been shown using taste‐intensity visual analog scales (VAS). VAS is often criticized because it is prone to halo‐dumping effects. We compared VAS and ranking methods to evaluate OITE in people living with normal‐weight or obesity. Sweet apple juice and salty green‐pea soup were spiked with either vanillin or bacon odorants to produce OITE. In the VAS experiment, saltiness, sweetness, sourness, bitterness and the global aroma intensities were evaluated for each base with and without the odorants. The ranking task consisted in ranking from the lowest to the highest sweetness/saltiness intensities, three references with increasing tastant concentration and a target solution with the lowest tastant concentration and the odorant. VAS highlighted OITE neither in the apple juice nor in the green‐pea soup, in no group. The ranking method revealed an OITE in the green‐pea soup in both groups, and only the group with obesity experienced OITE in the apple juice. Practical Applications: The ranking task appears as an optimal method to highlight OITE and is sufficiently sensitive to demonstrate subtle differences related to participants' weight status. The ranking task is easy to perform, does not require training and does not imply a high number of participants to be statistically powered. Odor‐Induced Taste Enhancement is a strategy that might be employed to significantly reduce salt, and sugar, while maintaining an acceptable taste intensity, at home as well as in food formulation by the industry. [ABSTRACT FROM AUTHOR]

Semantic description of odors is a cognitively demanding task. Learning to name smells is, however, possible with training. This study set out to examine how improvement in olfactory semantic knowledge following training reorganizes the neural representation of smells. First, 19 nonexpert volunteers were trained for 3 days; they were exposed (i) to odorants presented without verbal labels (perceptual learning) and (ii) to other odorants paired with lexicosemantic labels (associative learning). Second, the same participants were tested in a brain imaging study (fMRI) measuring hemodynamic responses to learned odors presented in both the perceptual and associative learning conditions. The lexicosemantic training enhanced the ability to describe smells semantically. Neurally, this change was associated with enhanced activity in a set of heteromodal areas-including superior frontal gyrus-and parietal areas. These findings demonstrate that odor-name associative learning induces recruitment of brain areas involved in the integration and representation of semantic attributes of sensory events. They also offer new insights into the brain plasticity underlying the acquisition of olfactory expertise in lay people. Hum Brain Mapp 38:5958-5969, 2017. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Burning mouth syndrome ( BMS) is characterized by a burning sensation in the mouth, usually in the absence of clinical and laboratory findings. Latest findings indicate that BMS could result from neuropathic trigeminal conditions. While many investigations have focused on the periphery, very few have examined possible central dysfunctions. To highlight changes of the central system of subjects with BMS, we analysed the grey matter concentration in 12 subjects using voxel-based morphometry. Data were compared with a control group (Ct). To better understand the brain mechanisms underlying BMS, the grey matter concentration of patients was also compared with those of dysgeusic patients (Dys). Dysgeusia is another oral dysfunction condition, characterized by a distorted sense of taste and accompanied by a reduced taste function. We found that a major part of the 'pain matrix' presented modifications of the grey matter concentration in subjects with BMS. Six regions out of eight were affected [anterior and posterior cingulate gyrus, lobules of the cerebellum, insula/frontal operculum, inferior temporal area, primary motor cortex, dorsolateral pre-frontal cortex ( DLPFC)]. In the anterior cingulate gyrus, the lobules of the cerebellum, the inferior temporal lobe and the DLPFC, pain intensity correlated with grey matter concentration. Dys also presented changes in grey matter concentration but in different areas of the brain. Our results suggest that a deficiency in the control of pain could in part be a cause of BMS and that BMS and dysgeusia conditions are not linked to similar structural changes in the brain. [ABSTRACT FROM AUTHOR]