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SCENTinel, a rapid smell test designed to screen for olfactory disorders, including anosmia (no ability to smell an odor) and parosmia (distorted sense of smell), measures 4 components of olfactory function: detection, intensity, identification, and pleasantness. Each test card contains one of 9 odorant mixtures. Some people born with genetic insensitivities to specific odorants (i.e. specific anosmia) may fail the test if they cannot smell an odorant but otherwise have a normal sense of smell. However, using odorant mixtures has largely been found to prevent this from happening. To better understand whether genetic differences affect SCENTinel test results, we asked genetically informative adult participants (twins or triplets, N = 630; singletons, N = 370) to complete the SCENTinel test. A subset of twins (n = 304) also provided a saliva sample for genotyping. We examined data for differences between the 9 possible SCENTinel odors; effects of age, sex, and race on SCENTinel performance, test-retest variability; and heritability using both structured equation modeling and SNP-based statistical methods. None of these strategies provided evidence for specific anosmia for any of the odors, but ratings of pleasantness were, in part, genetically determined (h2 = 0.40) and were nominally associated with alleles of odorant receptors (e.g. OR2T33 and OR1G1; P < 0.001). These results provide evidence that using odorant mixtures protected against effects of specific anosmia for ratings of intensity but that ratings of pleasantness showed effects of inheritance, possibly informed by olfactory receptor genotypes., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The aroma of mint is well-liked by the public, and key flavor odorants in mint aroma had been found, but how these molecules interact and form a satisfying odor remains a challenge. Quality, intensity, and pleasantness are our most basic perceptions of aromas; both intensity and pleasantness can be quantified. However, compared to intensity, research on pleasantness was lacking. Pleasantness was one of the most important indicators for formulating a satisfying mint flavor, and the study of binary mixtures was fundamental to our understanding of more complex mixtures. Therefore, the purpose of this study was to explore the characteristics of pleasantness as a function of concentration and, at the same time, to investigate the relationship between intensity and pleasantness in binary mixtures. Thirty sensory evaluation volunteers participated in the evaluation of the intensity and pleasantness of six key flavor odorants of mint and five binary mixtures. The results showed that the pleasantness increased first and then decreased or stabilized with the rising of concentration; even though the interactions in binary mixtures were not the same, their pleasantness could be predicted using the intensities of the components by Response Surface Design of Experiments, and the goodness of fit was greater than 0.92, indicating that the models had the great predictive ability. PRACTICAL APPLICATION: Whether blending flavors or evaluating them, a great deal of experience is required, yet the acquisition of this experience is a long process. Performing these tasks is difficult for the novice, and it helps to quantify the feeling for the flavor and build some mathematical models., (© 2023 Institute of Food Technologists.)

Determining the valence of an odor to guide rapid approach-avoidance behavior is thought to be one of the core tasks of the olfactory system, and yet little is known of the initial neural mechanisms supporting this process or of its subsequent behavioral manifestation in humans. In two experiments, we measured the functional processing of odor valence perception in the human olfactory bulb (OB)-the first processing stage of the olfactory system-using a noninvasive method as well as assessed the subsequent motor avoidance response. We demonstrate that odor valence perception is associated with both gamma and beta activity in the human OB. Moreover, we show that negative, but not positive, odors initiate an early beta response in the OB, a response that is linked to a preparatory neural motor response in the motor cortex. Finally, in a separate experiment, we show that negative odors trigger a full-body motor avoidance response, manifested as a rapid leaning away from the odor, within the time period predicted by the OB results. Taken together, these results demonstrate that the human OB processes odor valence in a sequential manner in both the gamma and beta frequency bands and suggest that rapid processing of unpleasant odors in the OB might underlie rapid approach-avoidance decisions., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

Although pleasantness is intrinsically related to the perception of odors it is difficult to objectively assess odor-induced pleasantness. To evaluate the effects of odors of different valences on the contingent negative variation (CNV) in a younger and an older population. Data from 62 participants (27 men, 35 women) were included. Two age groups with Age group 1 (YOUNG) had 30 subjects within age 18-30 years and age group 2 (OLD) had 32 subjects with age >40 years. Pre-testing was performed to acquaint subjects with the experimental tasks and their environment. Subjects received "Sniffin' Sticks" odor identification tests and a standardized medical history to ascertain normosmia. In addition, they also took questionnaires relating to importance of the sense of smell and personality traits. CNV was elicited with two auditory stimuli, S1 followed by S2 at an interval of 2.4 s. Subjects were asked to push a button as fast as possible after they perceived S2. EEG was recorded from 4 positions of the 10-20 system (Fp2, Fz, Cz, and Pz). Four odors plus odorless air was presented in randomized order. The following main results emerged: (1) Consistent with the literature CNV showed a typical topographical distribution with the largest amplitude over the front-central recording sites. (2) 69% of subjects had consistent CNV for all conditions. (3) for some odor conditions CNV amplitudes exhibit a weak relation to odor pleasantness and associations with calmness. (4) CNV amplitude correlated negatively with reaction times. Overall, the results suggest the usefulness of CNV as an electrophysiological measure of cognition. However, in the present context, concomitantly applied odors of different hedonic tones exerted only minor effects on CNV. Thus, we conclude that odors have little or no effect on CNV., (Copyright © 2021 IBRO. Published by Elsevier Ltd. All rights reserved.)

This study explored the impact of perceptual interactions on the odor intensity of 222 binary mixtures designed from 72 odorants found in food products. Odor intensity was rated by 30 trained subjects. The results showed that in most cases, the components' odor was perceived within the mixture and their intensity remained the same as in the unmixed situation in 54.3% of cases. Masking was the second major effect (44.8%) and occurred more frequently when components' pleasantness was significantly different. Synergy occurred in a small number of cases (0.9%) and only for four compounds. The overall odor intensity of the mixture was determined to be equal to the strongest component in most cases (73.9%), while partial addition was observed as the second most frequent effect (21.7%), especially when the components had equal intensity. Overall, this work provides general rules about the outcome to expect when mixing key components of food aromas., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Whereas contextual influences in the visual and auditory domains have been largely documented, little is known about how chemical senses might be affected by our multisensory environment. In the present study, we aimed to better understand how a visual context can affect the perception of a rather pleasant (floral) and a rather unpleasant (damp) odor. To this end, 19 healthy participants performed a series of tasks including odor detection followed by perceptual evaluations of odor intensity, pleasantness, flowery, and damp characters of both odors presented at 2 different concentrations. A visual context (either congruent or incongruent with the odor; or a neutral control context) preceded odor stimulations. Olfactomotor responses as well as response times were recorded during the detection task. Results showed an influence of the visual context on semantic and motor responses to the target odors. First, congruency between context and odor increased the saliency of the olfactory feature of the memory trace, for the pleasant floral odor only (higher perceived flowery note). Clinical applications of this finding for olfactory remediation in dysosmic patients are proposed. Second, the unpleasant odor remained unaffected by visual primes, whatever the condition. In addition, incongruency between context and odor (regardless of odor type) had a disruptive effect on odor sampling behavior, which was interpreted as a protective behavior in response to expectancy violation. Altogether, this second series of effects may serve an adaptive function, especially the avoidance of, or simply vigilance toward, aversive and unpredictable stimuli., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Humans can accurately discern thousands of odorants, although there is a considerable inter-individual variability. Individuals can be classified as normosmic, hyposmic or anosmic, depending on their olfactory sensitivity or blindness. In this research we studied the olfactory sensitivity to banana head-space as a complex odor mixture in a group of 53 subjects classified for their olfactory status, by means of the "Sniffin' Sticks" extended test. Using the coupled Gas Chromatography-Mass Spectrometry/ Olfactometry (GC-MS/O) technique, the single components of the banana flavor mixture were separated, identified and verbally evaluated by each subject. For each compound both the "odor type" (i.e., odor quality: fruity, floral, green, etc.) and "odor descriptor" (i.e., name used by subjects for odor identification) were reported, so that we could identify molecules that were defined as smelling of banana. The results show that: (a) the threshold olfactory performance is linearly correlated with the number of odor-active compounds (total or smelling of banana) for each subject; (b) the intensity reported by each subject during the sniffing of the pen containing the banana aroma in the identification test is positively correlated both with its hedonic valence and the number of odor-active compounds smelling of banana. In conclusion, our findings show that human perception of single compounds is conditioned by the threshold olfactory performance of the subject and that his/her ability to detect single molecular components, which smell as the mixture, affects the intensity and hedonism for the complex aroma., Competing Interests: Declaration of Competing Interests All authors declare no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A study of olfactory function was performed in 15 bronchial cancer patients receiving cisplatin and 15 control subjects. Whereas odor detection and odor identification abilities were not influenced by the administration of cisplatin, a decrease in pleasantness was observed only for food odors, and not for non-food odors. Taken as a whole, these findings suggest that cisplatin therapy in bronchial cancer patients impairs the pleasure of perceived food odors, which may account for disturbances in food intake and quality of life in this population., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Different psychophysical works have reported that, when a wide range of odors is assessed, the hedonic dimension is the most salient. Hence, pleasantness is the most basic attribute of odor perception. Recent studies suggest that the molecular size of a given odorant is positively correlated with its hedonic character. This correlation was confirmed in the present study, but further basic molecular features affecting pleasantness were identified by means of multiple linear regression for the compounds contained in five chemical sets. For three of them, hedonic judgments are available in the literature. For a further two chemical sets, hedonic scores were estimated from odor character descriptions based on numerical profiles. Generally speaking, fairly similar equations were obtained for the prediction of hedonic judgments in the five chemical sets, with R(2) values ranging from 0.46 to 0.71. The results suggest that larger molecules containing oxygen are more likely to be perceived as pleasant, while the opposite applies to carboxylic acids and sulfur compounds.

Odor hedonic estimation (pleasant/unpleasant) is considered the first and one of the most important dimensions in odor perception. Although there are several published scales that rate odor hedonicity, most of them use odorants that induce biases related to stimulus properties or test conditions and make difficult clinical or industrial applications. Thus, this study aimed to propose a model of odor hedonic profile (OHP) based on 14 items related to everyday odors without stimulus. The OHP is a self-rating tool based on the hedonic estimate representation and allows the determination of specific profiles, i.e., “conservative,” “neutral,” “liberal,” “negative olfactory alliesthesia,” and “positive olfactory alliesthesia.” It can be useful in dierent contexts (e.g., food studies) and general pathologies (e.g., eating disorders) or pathologies with mood/emotional disturbances (e.g., depression) [ABSTRACT FROM AUTHOR]

Emotion evoked by odours can be determined or modulated by several factors, including odorant–receptor interactions and olfactory experiences. As a result of these factors, some odours can induce an emotional discrepancy, such as a conflict between innately determined and experience‐based emotions. This study examined whether the difference between two subjective ratings, pleasantness and liking, for an odour can influence olfactory perception, and explored whether the emotional discrepancy had any effect on olfaction. We conducted a psychophysical experiment wherein 12 participants (six women and six men, mean age = 22.0 years) evaluated 36 odours. Participants were instructed to evaluate each odorant in terms of four qualities: (i) pleasantness, (ii) liking, (iii) olfactory perceptual descriptors, and (iv) odour intensity. Participants were also asked to note the difference between pleasantness and liking, whereby the former referred to instinctive and innate feelings and the latter to experience‐based and acquired feelings. Ten odorants exhibited a discrepancy between pleasantness and liking ratings. Another 10 odorants exhibited a significant relationship between the choice of perceptual descriptors and intensity; this was not true of the 10 discrepant odorants. This preliminary study showed that differences in pleasantness and liking ratings can affect the selection of olfactory descriptors, according to odour intensity. The findings suggest that olfactory lexical semantic representations could be confused by discrepant odour‐evoked emotions. Psychophysical experiments demonstrated a difference between subjective ratings for an odour, innate pleasantness and acquired liking. Our results could indicate that the difference influenced the selection of olfactory perceptual descriptors according to odor intensity. [ABSTRACT FROM AUTHOR]

Hedonic ratings of odors and olfactory preferences are influenced by a number of modulating factors, such as prior experience and knowledge about an odor’s identity. The present study addresses the relationship between knowledge about an odor’s identity due to prior experience, assessed by means of a test of cued odor identification, and odor pleasantness ratings in children who exhibit ongoing olfactory learning. Ninety-one children aged 8-11 years rated the pleasantness of odors in the Sniffin’ Sticks set and, subsequently, took the odor identification test. A positive association between odor identification and pleasantness was found for two unpleasant food odors (garlic and fish): higher pleasantness ratings were exhibited by those participants who correctly identified these odors compared to those who failed to correctly identify them. However, we did not find a similar effect for any of the more pleasant odors. The results of this study suggest that pleasantness ratings of some odors may be modulated by the knowledge of their identity due to prior experience and that this relationship might be more evident to unpleasant odors.

Typically, the subjective pleasantness of an odor decreases after it has been repeatedly smelled. This study investigates how the pleasantness ("liking") and the wish to be further exposed to the same odor ("wanting") are affected by variety on a longer time scale, and how they relate to actual food intake. Twenty-five participants rated a coconut odor presented 120 times for its liking and wanting before being offered coconut sweets. The amount eaten was assessed. Individual patterns of change were described by fitting 3 different models to the ratings. To study effects of variety on odor evaluation, the ratings were compared with a previous study where coconut was 1 of 3 odors presented in an alternating way. Initially, both liking and wanting the odors were high, but decreased over repetitions in 75% of the subjects. About 40% of all subjects showed an exponential change of ratings, 40% a step-like change, and 20% a linear change. Food intake was not related to the pattern of change in the ratings. Moreover, decreased olfactory pleasure did not seem to affect eating behavior. However, participants who rated the coconut odor higher at the beginning ate twice as many sweets as the others. Odor variety did not affect the experienced pleasure of smelling (liking), but did affect the motivation to experience the same smell again (wanting). This has not been reported for food or touch stimulation and may be specific for the perception of odors. [ABSTRACT FROM AUTHOR]

Given the strong relationship between human olfaction and emotion, it is not surprising that numerous studies have investigated human response to hedonic and arousing qualities of odors. However, neuropsychological research addressed rather the pleasant–unpleasant, and not the arousing–calming dimension of emotional states generated by odorants. The purpose of the presented fMRI study was to evaluate the differences in cerebral processing of olfactory stimuli, focusing on both of these dimensions of emotional experiences, i.e., pleasantness and arousal. We investigated the patterns of activation generated by odors differing in hedonic tone and generated arousal while controlling the stimuli intensity. This design allowed for a new insight to the emotional odor processing with imaging techniques. The pleasantness was related to activation in the cingulate gyrus, the insula, the hippocampal area, the amygdala, and the superior temporal gyrus, whereas arousal affected activation in the thalamic relay. The present study showed also that the emotional states generated by arousing qualities of odorants are an important determinant of magnitude of cerebral activation. [ABSTRACT FROM AUTHOR]

Background: As evidenced in the DSM-V, autism spectrum disorders (ASD) are often characterized by atypical sensory behavior (hyper- or hypo-reactivity), but very few studies have evaluated olfactory abilities in individuals with ASD. Methods: Fifteen adults with ASD and 15 typically developing participants underwent olfactory tests focused on superficial (suprathreshold detection task), perceptual (intensity and pleasantness judgment tasks), and semantic (identification task) odor processing. Results: In terms of suprathreshold detection performance, decreased discrimination scores and increased bias scores were observed in the ASD group. Furthermore, the participants with ASD exhibited increased intensity judgment scores and impaired scores for pleasantness judgments of unpleasant odorants. Decreased identification performance was also observed in the participants with ASD compared with the typically developing participants. This decrease was partly attributed to a higher number of near misses (a category close to veridical labels) among the participants with ASD than was observed among the typically developing participants. Conclusions: The changes in discrimination and bias scores were the result of a high number of false alarms among the participants with ASD, which suggests the adoption of a liberal attitude in their responses. Atypical intensity and pleasantness ratings were associated with hyperresponsiveness and flattened emotional reactions, respectively, which are typical of participants with ASD. The high number of near misses as non-veridical labels suggested that categorical processing is functional in individuals with ASD and could be explained by attention deficit/hyperactivity disorder. These findings are discussed in terms of dysfunction of the olfactory system. [ABSTRACT FROM AUTHOR]

Background: Studies of olfaction in Alzheimer's disease (AD) mainly focused on deficits in odor detection and identification, with very few investigations of olfactory emotional changes and their consequences for hedonics.Objective: The aim of the present study was to characterize affective evaluations of odors in AD patients.Methods: To this end, 20 AD patients and 20 matched controls were tested. Participants were screened for odor detection and identification ability and then asked to rate the intensity, pleasantness, and edibility of 20 odorants.Results: Results showed that, overall, AD patients had lower detection ability and perceived all odors as weaker than controls. As expected, they had lower identification ability on both cued and non-cued tasks. In addition, when smelling pleasant odors, patients had significantly lower hedonic ratings than controls (p <  0.02), whereas no group difference was found for neutral or unpleasant odors (p >  0.05 in both cases). Moreover, an analysis combining both intensity and pleasantness ratings showed that whereas intensity increased as a function of pleasantness and unpleasantness in controls, this quadratic relationship was not observed in AD patients.Conclusions: The study suggests that the simplest categorization criteria of odors (intensity and hedonic valence) are impaired in AD patients (especially for pleasant odors). [ABSTRACT FROM AUTHOR]

Olfactory perception, and especially hedonic evaluation of odors, is highly flexible, but some mechanisms involved in this flexibility remain to be elucidated. In the present study we aimed at better understanding how repeated exposure to odors can affect their pleasantness. We tested the hypothesis of an affective habituation to the stimuli, namely a decrease of emotional intensity over repetitions. More specifically, we tested whether this effect is subject to inter-individual variability and whether it can also be observed at the olfactomotor level. Twenty-six participants took part in the experiment during which they had to smell two odorants, anise and chocolate, presented twenty times each. On each trial, sniff duration and volume were recorded and paired with ratings of odor pleasantness and intensity. For each smell, we distinguished between likers and dislikers, namely individuals giving positive and negative initial hedonic evaluations. Results showed a significant decrease in pleasantness with time when the odor was initially pleasant (likers), while unpleasantness remained stable or slightly decreased when the odor was initially unpleasant (dislikers). This deviation towards neutrality was interpreted as affective habituation. This effect was all the more robust as it was observed for both odors and corroborated by sniffing, an objective measurement of odor pleasantness. Affective habituation to odors can be interpreted as an adaptive response to stimuli that prove over time to be devoid of positive or negative outcome on the organism. This study contributes to a better understanding of how olfactory preferences are shaped through exposure, depending on the individual’s own initial perception of the odor.

Hedonic ratings of odors and olfactory preferences are influenced by a number of modulating factors, such as prior experience and knowledge about an odor's identity. The present study addresses the relationship between knowledge about an odor's identity due to prior experience, assessed by means of a test of cued odor identification, and odor pleasantness ratings in children who exhibit ongoing olfactory learning. Ninety-one children aged 8-11 years rated the pleasantness of odors in the Sniffin' Sticks test and, subsequently, took the odor identification test. A positive association between odor identification and pleasantness was found for two unpleasant food odors (garlic and fish): higher pleasantness ratings were exhibited by those participants who correctly identified these odors compared to those who failed to correctly identify them. However, we did not find a similar effect for any of the more pleasant odors. The results of this study suggest that pleasantness ratings of some odors may be modulated by the knowledge of their identity due to prior experience and that this relationship might be more evident in unpleasant odors. [ABSTRACT FROM AUTHOR]

This study aimed to examine the age-related differences in the olfactory-visual cross-correspondences and the extent to which they are moderated by the odors pleasantness. Sixty participants aged from 20- to 75- years (young, middle-aged and older adults) performed a priming task to explore the influence of six olfactory primes (lemon, orange, rose, thyme, mint and fish) on the categorization (cool vs. warm) of six subsequent color targets (yellow, orange, pink, malachite green, grass-green, and blue-gray). We tested mixed effects models. Response times were regressed on covariates models using both fixed effects (Groups of age, olfactory Pleasantness and multimodal Condition) and cross-random effects (Subject, Color and Odor). The random effects coding for Odor ( p < .001) and Color ( p = .001) were significant. There was a significant interaction effect ( p= .004) between Condition × Pleasantness, but not with Groups of age. The compatibility effect ( i.e., when odors and colors were congruent, the targets processing were facilitated) was as much enhanced as the olfactory primes were pleasant. Cross-correspondences between olfaction and vision may be robust in aging. They should be considered alongside spatiotemporal but also emotional congruency. [ABSTRACT FROM AUTHOR]

Objective: There is increasing evidence that schizophrenia patients have difficulties in the hedonic appraisal of odors. In a prior study, we assessed olfactory hedonic perception birhinally and found that males with schizophrenia failed to attach the appropriate hedonic valence to a pleasant odor, despite correctly perceiving changes in odor intensity. Female patients, in contrast, exhibited normal responses. The current study extends this work by examining odor valence processing in unaffected first-degree relatives of schizophrenia patients, to determine the extent to which this abnormality may be genetically mediated. We also examine odor valence processing unirhinally, rather than birhinally, to probe possible lateralized differences in patients’ hedonic processing deficits. Method: Individuals with schizophrenia (n = 54), first-degree unaffected family members (n = 22), and demographically matched controls (n = 45) were administered the Suprathreshold Amyl Acetate Odor Intensity and Odor Pleasantness Rating Test. Results: In contrast to family members and controls, both male and female schizophrenia probands underevaluated the hedonic characteristics of amyl acetate at lower concentrations and overevaluated its pleasantness at concentrations perceived as unpleasant by both controls and relatives. These patient-specific differences could not be explained by differences in smoking habit, medication use, or subjective ratings of odor intensity. However, they were associated with increased levels of anhedonia/asociality and negative symptomatology. Conclusions: Our findings suggest that both male and female schizophrenia patients have difficulties in the unirhinal appraisal of hedonic valence. Normal responses in unaffected first-degree relatives suggest that this is an environmentally, rather than genetically, mediated abnormality denoting negative symptomatology. [ABSTRACT FROM PUBLISHER]

The aim of our study was to explore possible differences in estimation of odor pleasantness in children with autism spectrum disorders (ASD) compared to controls. Thirty-five patients with Asperger's syndrome and high functioning autism (mean age 10.8 ± 3.6 years; 31 boys) were compared with 35 healthy control subjects (mean age 10.4 ± 2.4 years; 28 boys). Odor pleasantness was assessed on a 5-point scale using the Sniffin' Sticks test (Identification part of the test). Patients with ASD, compared to healthy controls, perceived the smell of cinnamon and pineapple as significantly less pleasant ( p < 0.05); at the trend level, the same was true of cloves ( p < 0.1). The possibility of olfactory dysfunctions as an autism biomarker is discussed. [ABSTRACT FROM AUTHOR]

Olfaction is often referred to as a multidimensional sense. It is multidimensional in that ∼1000 different receptor types, each tuned to particular odor aspects, together contribute to the olfactory percept. In humans, however, this percept is nearly unidimensional. Humans can detect and discriminate countless odorants, but can identify few by name. The one thing humans can and do invariably say about an odor is whether it is pleasant or not. We argue that this hedonic determination is the key function of olfaction. Thus, the boundaries of an odor object are determined by its pleasantness, which—unlike something material and more like an emotion—remains poorly delineated with words. [ABSTRACT FROM AUTHOR]

Abstract: Relative reward value is important for the choice between a set of available rewards, and absolute reward value for stable and consistent economic choice. It is unclear whether in the human brain subjective absolute value representations can be dissociated from relative reward value representations. Using fMRI, we investigated how the subjective pleasantness of an odor is influenced by whether the odor is presented in the context of a relatively more pleasant or less pleasant odor. We delivered two of a set of four odors separated by a delay of 6 s, with the instruction to rate the pleasantness of the second odor, and searched for brain regions where the activations were correlated with the absolute pleasantness rating of the second odor, and for brain regions where the activations were correlated with the difference in pleasantness of the second from the first odor, that is, with relative pleasantness. Activations in the anterolateral orbitofrontal cortex tracked the relative subjective pleasantness, whereas activations in the anterior insula tracked the relative subjective unpleasantness. In contrast, in the medial and midorbitofrontal cortex activations tracked the absolute pleasantness of the stimuli. Thus, both relative and absolute subjective value signals which provide important inputs to decision-making processes about which stimulus to choose are separately and simultaneously represented in the human brain. [Copyright &y& Elsevier]

Abstract: Aim of the present study was to examine whether odor attributes like pleasantness and familiarity change in relation to the time of the year. In the first part of the study a total of 100 subjects answered to questions without odor presentation whether a certain odor was more related to summertime or Christmas season. Another 41 and 51 subjects rated the familiarity and hedonicity of 12 odors either during summertime or Christmas season, respectively. Importantly, this investigation was performed at the same place within a science museum during stable environmental conditions. Subjects reported that rose odor was more related to summertime, whereas orange, cinnamon, and cloves were more associated with Christmas season with cinnamon being most intimately connected to this time of the year. Moreover, subjects showed significantly higher familiarity and pleasantness ratings when they smelled cinnamon during the Christmas season than during summertime. Taken together, this study demonstrated that attributes of some odors change throughout the year. [Copyright &y& Elsevier]

Like odor perception, odor imagery is characterized by wide variability between individuals. The present two-part study sought to assess whether this inter-individual variability is underlain by behavioral differences in actual odor perception. In study 1, subjects judged the intensity, pleasantness, familiarity and edibility of 3 odorants. Participants were split into two olfactory imagery groups (“good” versus “poor” olfactory imagers) according to their scores on an imagery questionnaire. Results showed that good olfactory imagers judged all odors as more familiar and more edible than did poor olfactory imagers. Study 2 sought to determine whether these effects derived from a particular strategy of reenacting olfactomotor responses to smells on the part of good olfactory imagers, by recording their sniffs during odor perception. Results revealed that good olfactory imagers sniffed all odors longer and, again, judged these same odors as more edible and familiar. This supports the hypothesis of more complete odor processing and better access to odor semantics in good olfactory imagers. [ABSTRACT FROM AUTHOR]

Abstract: Recently, we found that healthy young adults remember odors leading to large emotional reactions better than odors provoking smaller emotional reactions. Because the amygdala is believed to be critically implicated in memory for emotionally arousing information and because it is part of the primary olfactory area, we hypothesized that patients with a unilateral medial temporal-lobe resection including the amygdala would not show enhanced memory for arousing compared to nonarousing odors. We tested odor memory in 19 patients (10 left, 9 right) who had undergone a unilateral medial temporal-lobe resection including the amygdala (MTLR) for treatment of intractable epilepsy and 19 healthy control subjects. Healthy individuals and patients with left or right MTLR showed comparable subjective emotional reactions to odors. Similarly, healthy individuals and patients with MTLR remembered unpleasant odors better than pleasant ones. However, unlike healthy individuals, patients with MTLR did not show better memory for emotionally arousing odors compared to nonarousing ones. Patients undergoing a MTLR, whether in the left or right hemisphere, lose the specific memory advantage that odors causing strong emotional reactions normally have. [Copyright &y& Elsevier]

Although it is agreed that physicochemical features of molecules determine their perceived odor, the rules governing this relationship remain unknown. A significant obstacle to such understanding is the high dimensionality of features describing both percepts and molecules. We applied a statistical method to reduce dimensionality in both odor percepts and physicochemical descriptors for a large set of molecules. We found that the primary axis of perception was odor pleasantness, and critically, that the primary axis of physicochemical properties reflected the primary axis of olfactory perception. This allowed us to predict the pleasantness of novel molecules by their physicochemical properties alone. Olfactory perception is strongly shaped by experience and learning. However, our findings suggest that olfactory pleasantness is also partially innate, corresponding to a natural axis of maximal discriminability among biologically relevant molecules. [ABSTRACT FROM AUTHOR]

We report an experiment designed to investigate whether olfactory cues can influence people's judgments of facial attractiveness. Sixteen female participants judged the attractiveness of a series of male faces presented briefly on a computer monitor using a 9-point visual rating scale. While viewing each face, the participants were simultaneously presented with either clean air or else with 1 of 4 odorants (the odor was varied on a trial-by-trial basis) from a custom-built olfactometer. We included 2 pleasant odors (geranium and a male fragrance) and 2 unpleasant odors (rubber and body odor) as confirmed by pilot testing. The results showed that the participants rated the male faces as being significantly less attractive in the presence of an unpleasant odor than when the faces were presented together with a pleasant odor or with clean air (these conditions did not differ significantly). These results demonstrate the cross-modal influence that unpleasant odors can have on people's judgments of facial attractiveness. Interestingly, this pattern of results was unaffected by whether the odors were body relevant (the body odor and the male fragrance) or not (the rubber and geranium odors). [ABSTRACT FROM AUTHOR]

Investigating the neural substrates of perceived quality in olfaction using different odorants is intrinsically difficult. By utilizing individual differences in perceived quality of the odor of androstenone, we obtained a continuum of individual differences in rated valence of the same stimulus allowing investigations of its manifestation in the olfactory event-related potentials (ERPs). In an initial group consisting of 43 individuals that were screened for their verbal descriptors and sensitivity for the odor of androstenone, 22 normosmic volunteers were chosen forming 2 distinct groups with regard to verbal labels (“body odor” and “nonbody odor”) for androstenone while maintaining chemical structure, concentration, and intensity constant. In the main experiment, these participants rated both intensity and pleasantness of androstenone during the recording of olfactory ERPs. There was a significant difference in rated valence between the groups but not in intensity. Participants in the body odor label group had larger amplitudes of the late positive ERP component than those in the nonbody odor label group. A negative correlation between valence and amplitudes of the late positive component for androstenone indicated that these differences were mediated by the difference in odor valence between the 2 groups. This was further supported by a comparison of ERP peaks in response to stimulation with androstenone and the invariably unpleasant hydrogen sulfide that had been used as a control. Altogether, the results suggest that the late positive component reflects the processing of odor valence. Future olfactory studies with the aim of assessing the dimension of pleasantness would benefit from the use of these interindividual differences in the perception of a specific odor. [ABSTRACT FROM AUTHOR]

The stimuli used in taste research are usually considered to be odourless. This was tested in two experiments with aqueous solutions of two representative compounds for each of the five taste qualities including umami. In the first experiment elderly and young subjects rated the intensity and pleasantness of three concentrations of the stimuli, while wearing or not wearing a noseclip. Saliva production was also measured. Blocking olfaction only influenced salivation for umami. It reduced taste intensity ratings, but as in an earlier experiment with the same compounds in food products, this effect was stronger in the young, who also liked the stimuli better wearing the noseclip. In the second experiment, another group of young people tried to detect the odours of the tastants dissolved in demineralized, double-distilled or Evian water. A considerable number of subjects could regularly detect seven of the ten tastants by olfaction and the extent to which they did correlated significantly with the reduction in taste intensity ratings for the different tastants found in the first experiment. We suggest that most tastants can be smelled and that this smell contributes to taste intensity ratings. [ABSTRACT FROM AUTHOR]

Food intake is an essential human activity regulated by homeostatic and hedonic systems in the brain which has mostly been ignored by the cognitive neurosciences. Yet, the study of food intake integrates fundamental cognitive and emotional processes in the human brain, and can in particular provide evidence on the neural correlates of the hedonic experience central to guiding behaviour. Neuroimaging experiments provide a novel basis for the further exploration of the brain systems involved in the conscious experience of pleasure and reward, and thus provide a unique method for studying the hedonic quality of human experience. Recent neuroimaging experiments have identified some of the regions involved in the cortical networks mediating hedonic experience in the human brain, with the evidence suggesting that the orbitofrontal cortex is the perhaps strongest candidate for linking food and other kinds of reward to hedonic experience. Based on the reviewed literature, a model is proposed to account for the roles of the different parts of the orbitofrontal cortex in this hedonic network. [Copyright &y& Elsevier]

Hedonic tone is so salient in odor perception that several authors have used odors to induce affective states. Various studies have shown that the electrophysiological and psychophysiological response patterns induced by olfactory stimuli are different for pleasant and unpleasant odors, and that these types of odor activate brain structures differentially. These results suggest that odors are first categorized according to pleasantness. The objective of the present work was to study the possible existence of an involuntary affective categorization in olfaction. Given that certain variations in the autonomic system, such as skin conductance amplitude and heart rate, are not under the voluntary control of human subjects, we used such psychophysiological methods for this investigation. Our results indicate that unpleasant odors provoke heart-rate acceleration during both a smelling task (control condition: a task in which subjects had only to inhale odors) and a pleasantness judgment, but not during a familiarity judgment. These results suggest that subjects involuntarily categorize odors by their pleasantness. [Copyright &y& Elsevier]