Viewing Olfactory Affective Responses Through the Sniff Prism: Effect of Perceptual Dimensions and Age on Olfactomotor Responses to Odors

Olfactory Obsessions: A Study of Prevalence and Phenomenology in the Course of Obsessive-Compulsive Disorder

Olfactory obsessions (OOs) are rarely described in the medical literature. The features of OOs appear consistent with characteristics of a typical obsession, but since they do not involve the realm of thought, it is questionable to term them obsessions per se. Olfactory Reference Syndrome (ORS) presents OOs inconsistently and is a distinctive diagnostic category related to OCD. Therefore, the primary objectives of our study were not only to assess the prevalence of OOs in OCD patients, but also to demonstrate their phenomenological consistency with other OCD symptoms. The study group consisted of 75 patients already diagnosed and treated for OCD. Hence, a comparison was made between OCD patients with and without OOs in terms of: symptom severity, level of insight and comorbidities. Olfactory obsessions (OOs) were found in 21.33% (n = 16). OOs induced compulsive behavior in more than 93% of subjects. The presence of OOs did not significantly differentiate the studied groups in terms of OCD severity (p = 0.876), level of insight (p = 0.680), depression (p = 0.746), mania (p = 0.525) and OCDP traits (p = 0.624). However, a comparison of the two groups showed that OOs patients presented higher levels of hostility (p = 0.036), cognitive impulsivity (p = 0.039), magic-type obsession (75% vs. 35.59%), and contamination obsession (87.50% vs. 67.80%). Conclusions: OOs frequently occur in the course of OCD, and their phenomenology is typical of this disorder. OOs are not a symptom of thought content disorders and are sensory in nature, which is not included in the definition of obsession. The presence of OOs in OCD provokes hostility and cognitive impulsivity. It can be assumed that the Olfactory Obsessions Questionnaire accurately identifies olfactory obsessions.

Identification of new behavioral parameters to assess odorant hedonic value in humans: A naturalistic approach

BACKGROUND

When you smell an odorant, your first reaction will certainly be either I like it or I dislike it. This primary reaction is a reflection of what is called the "hedonic value" of the odor. Very often, this hedonic value dominates the olfactory percept, more than olfactory identification or intensity. This component of olfactory perception is of primary importance for guiding behavior: avoiding danger (the smell of smoke, gas, etc.), consuming food, or seduction. Olfactory hedonics can be assessed using a large number of methods in humans, including psychophysical measures, autonomic responses, measurement of facial expressions or peripheral nervous activity. All of these techniques have their limitations: subjectivity, invasiveness, need for expertise, etc. A NEW METHOD: The olfactory system is closely linked to the reward system, the role of which is to mediate motivated behavior. In this context, we propose that the capacity odorants have of recruiting the reward system and thus inducing motivated behavior can be used to identify new behavioral parameters to assess odor hedonic value in humans.

RESULTS

We recorded freely moving human participants exploring odors emanating from flasks, and showed that five parameters linked to motivated behavior were closely linked to odor hedonics: speed of approach to the nose and withdrawal of the flask containing the odorant, distance between flask and nose, number of samplings, and withdrawal distance (maximal distance between nose and flask after odor sampling).

CONCLUSIONS

We highlighted new non-verbal and non-invasive parameters to evaluate olfactory hedonics in humans based on the assessment of odor-motivated behavior.

Gastrointestinal Interoception in Eating Disorders: Charting a New Path

PURPOSE OF REVIEW

Abnormal interoception has been consistently observed across eating disorders despite limited inclusion in diagnostic conceptualization. Using the alimentary tract as well as recent developments in interoceptive neuroscience and predictive processing as a guide, the current review summarizes evidence of gastrointestinal interoceptive dysfunction in eating disorders.

RECENT FINDINGS

Eating is a complex process that begins well before and ends well after food consumption. Abnormal prediction and prediction-error signals may occur at any stage, resulting in aberrant gastrointestinal interoception and dysregulated gut sensations in eating disorders. Several interoceptive technologies have recently become available that can be paired with computational modeling and clinical interventions to yield new insights into eating disorder pathophysiology. Illuminating the neurobiology of gastrointestinal interoception in eating disorders requires a new generation of studies combining experimental probes of gut physiology with computational modeling. The application of such techniques within clinical trials frameworks may yield new tools and treatments with transdiagnostic relevance.

Judgements of attractiveness of the opposite sex and nostril differences in self-rated mood: The effects of androstenol

Androstenol has been reported to influence judgements of attractiveness and to affect participants' mood. In the present study, participants were asked to sniff androstenol or a control odour (pure ethanol) unilaterally with the left or right nostril. Subsequently, they rated the attractiveness of photographs of the opposite sex and their own feelings on four mood scales. Participants rated the photographs as significantly more attractive after sniffing androstenol compared with the control odour. This did not depend upon androstenol being perceived as pleasant. Androstenol made male participants feel more lively, and both male and female participants more sexy, when sniffed through the right compared with the left nostril. Participants rated themselves as more irritable and aggressive when exposed to androstenol through the left nostril. The findings are discussed in relation to the effects of arousal on attraction and in the context of current theories of hemispheric differences in emotion.

Disgusting odours affect the characteristics of the Adaptive Force in contrast to neutral and pleasant odours

The olfactomotor system is especially investigated by examining the sniffing in reaction to olfactory stimuli. The motor output of respiratory-independent muscles was seldomly considered regarding possible influences of smells. The Adaptive Force (AF) characterizes the capability of the neuromuscular system to adapt to external forces in a holding manner and was suggested to be more vulnerable to possible interfering stimuli due to the underlying complex control processes. The aim of this pilot study was to measure the effects of olfactory inputs on the AF of the hip and elbow flexors, respectively. The AF of 10 subjects was examined manually by experienced testers while smelling at sniffing sticks with neutral, pleasant or disgusting odours. The reaction force and the limb position were recorded by a handheld device. The results show, inter alia, a significantly lower maximal isometric AF and a significantly higher AF at the onset of oscillations by perceiving disgusting odours compared to pleasant or neutral odours (p < 0.001). The adaptive holding capacity seems to reflect the functionality of the neuromuscular control, which can be impaired by disgusting olfactory inputs. An undisturbed functioning neuromuscular system appears to be characterized by a proper length tension control and by an earlier onset of mutual oscillations during an external force increase. This highlights the strong connection of olfaction and motor control also regarding respiratory-independent muscles.

Visual Priming Influences Olfactomotor Response and Perceptual Experience of Smells

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.

Clinical effects of two combinations of olfactory agents on olfactory dysfunction after upper respiratory tract infection during olfactory training

OBJECTIVE

To compare two combinations of olfactory agents for olfactory training therapy of olfactory dysfunction after upper respiratory tract infection (URTI) and investigate the influencing factors on clinical effects.

METHODS

125 patients with olfactory dysfunction were randomly divided into two groups: test and control. During the olfactory training, four odors were used in both groups. The olfactory training lasted for 24 weeks. Then, participants were tested using Sniffin' Sticks and threshold-discrimination-identification (TDI) composite scoring before treatment and at 1, 3, and 6 months after treatment. The TDI scores were compared at different time points between the groups and within them, and influence factors were analyzed.

RESULTS

There was no significant difference in TDI scores between both groups. Furthermore, TDI scores did not significantly change after one month of treatment in either of the groups. After 3 and 6 months of treatment, TDI scores both significantly increased, and the odor discrimination and identification abilities significantly strengthened in both groups; however, the odor thresholds did not improve. The course of the disease was a significant influencing factor on the therapeutic effect of olfactory training for both groups.

CONCLUSION

The combination of essential balm, vinegar, alcohol, and rose perfume for olfactory training, which are scents commonly found in daily life, can effectively cure URTI-induced olfactory dysfunction, and significantly improve the odor discrimination and identification abilities. Furthermore, prolonging the treatment time can help with the recovery of olfactory functions, and earlier olfactory training can improve the therapeutic effect.

Analysis of the clinical effect of olfactory training on olfactory dysfunction after upper respiratory tract infection

Background: Olfactory dysfunction is a common symptom during otolaryngology outpatient service. Objective: To explore the clinical effect of olfactory training on olfactory dysfunction after upper respiratory tract infection (URTI), and its influence factors. Material and methods: A total of 60 confirmed cases of URTI-induced olfactory dysfunction were enrolled into the present study. The olfactory training lasted for 24 weeks. These patients were tested using Sniffin' Sticks and threshold-discrimination-identification (TDI) composite scoring before treatment, and at 1, 3 and 6 months after treatment. Results: It was found that URTI-induced olfactory dysfunction patients had more evident deterioration in odor identification ability. The effective rates of olfactory training on olfactory dysfunction at 1, 3 and 6 months after treatment were 1.67%, 26.67% and 41.67%, respectively. The TDI scores at the 3rd and 6th months, but not at the 1st month, were significantly higher, when compared to those before treatment. The course of diseases was a significant influence factor on the therapeutic effect of olfactory training (OR = 0.805, 95% CI: 0.696-0.931). Conclusions: Olfactory training can efficiently cure URTI-induced olfactory dysfunction, and in particular, significantly improve the odor discrimination ability and odor identification ability. Significance: Providing useful data for further research regarding olfactory dysfunction.

IR thermography-based monitoring of respiration phase without image segmentation

BACKGROUND

Respiratory rate is an essential parameter in biomedical research and clinical applications. Most respiration measurement techniques in preclinical animal models require surgical implantation of sensors. Current clinical measurement modalities typically involve attachment of sensors to the patient, causing discomfort. We have previously developed a non-contact approach to measuring respiration phase in head-restrained rodents using infrared (IR) thermography. While the non-invasive nature of IR thermography offers many advantages, it also bears the complexity of extracting respiration signals from videos. Previously reported algorithms involve image segmentation to identify the nose in IR videos and extract breathing-relevant pixels which is particularly challenging if the videos have low contrast or suffer from suboptimal focusing.

NEW METHOD

To address this challenge, we developed a novel algorithm, which extracts respiration signals based on pixel time series, removing the need for nose-tracking and image segmentation.

RESULTS & COMPARISON WITH EXISTING METHODS

We validated the algorithm by performing respiration measurements in head-restrained mice and in humans with IR thermography in parallel with established standard techniques. We find the algorithm reliably detects inhalation onsets with high temporal precision.

CONCLUSIONS

The new algorithm facilitates the application of IR thermography for measuring respiration in biomedical research and in clinical settings.

Individual Differences in Verbal and Non-Verbal Affective Responses to Smells: Influence of Odor Label Across Cultures

Olfactory perception is highly variable from one person to another, as a function of individual and contextual factors. Here, we investigated the influence of 2 important factors of variation: culture and semantic information. More specifically, we tested whether cultural-specific knowledge and presence versus absence of odor names modulate odor perception, by measuring these effects in 2 populations differing in cultural background but not in language. Participants from France and Quebec, Canada, smelled 4 culture-specific and 2 non-specific odorants in 2 conditions: first without label, then with label. Their ratings of pleasantness, familiarity, edibility, and intensity were collected as well as their psychophysiological and olfactomotor responses. The results revealed significant effects of culture and semantic information, both at the verbal and non-verbal level. They also provided evidence that availability of semantic information reduced cultural differences. Semantic information had a unifying action on olfactory perception that overrode the influence of cultural background.