A randomized controlled trial investigating the effect of liraglutide on self-reported liking and neural responses to food stimuli in participants with obesity.

BACKGROUND/OBJECTIVES: Obesity is a complex condition and the mechanisms involved in weight gain and loss are not fully understood. Liraglutide, a GLP-1 receptor agonist, has been demonstrated to successfully promote weight loss in patients with obesity (OB). Yet, it is unclear whether the observed weight loss is driven by an alteration of food liking. Here we investigated the effects of liraglutide on food liking and the cerebral correlates of liking in OB. SUBJECTS/METHODS: This study was a randomized, single-center, double-blind, placebo-controlled, parallel group, prospective clinical trial. 73 participants with OB and without diabetes following a multidisciplinary weight loss program, were randomly assigned (1:1) to receive liraglutide 3.0 mg (37.40 ± 11.18 years old, BMI = 35.89 ± 3.01 kg) or a placebo (40.04 ± 14.10 years old, BMI = 34.88 ± 2.87 kg) subcutaneously once daily for 16 weeks. INTERVENTIONS/METHODS: We investigated liking during food consumption. Participants reported their hedonic experience while consuming a high-calorie food (milkshake) and a tasteless solution. The solutions were administered inside the scanner with a Magnetic Resonance Imaging (MRI)-compatible gustometer to assess neural responses during consumption. The same procedure was repeated during the pre- and post-intervention sessions. RESULTS: None of the effects involving the intervention factor reached significance when comparing liking between the pre- and post-intervention sessions or groups. Liking during food reward consumption was associated with the activation of the ventromedial prefrontal cortex (vmPFC) and the amygdala. The liraglutide group lost more weight (BMI post-pre = -3.19 ± 1.28 kg/m2) than the placebo group (BMI post-pre = -0.60 ± 1.26 kg/m2). CONCLUSIONS: These results suggest that liraglutide leads to weight loss without self-report or neural evidence supporting a concomitant reduction of food liking in participants with OB.

Reduction in sugar drink valuation and consumption with gamified executive control training.

The overvaluation of high-energy, palatable food cues contributes to unhealthy eating and being overweight. Reducing the valuation of unhealthy food may thus constitute a powerful lever to improve eating habits and conditions characterized by unhealthy eating. We conducted a double-blind, placebo-controlled, randomized intervention trial assessing the efficacy of a five to twenty days online cognitive training intervention to reduce sugary drink perceived palatability and consumption. Our intervention involved a recently identified action-to-valuation mechanism of action, in which the repeated inhibition of prepotent motor responses to hedonic food cues in a Go/NoGo (GNG) and an attentional bias modification (ABM) task eventually reduces their valuation and intake. Confirming our hypotheses, the experimental intervention with consistent (100%) mapping between motor inhibition and the targeted unhealthy sugary drinks cues induced a larger decrease in their valuation than the control intervention with inconsistent (50%) mapping (- 27.6% vs. - 19%), and a larger increase of the (water) items associated with response execution (+ 11% vs + 4.2%). Exploratory analyses suggest that the effect of training on unhealthy items valuation may persist for at least one month. Against our hypothesis, we observed equivalent reductions in self-reported consumption of sugary drinks following the two interventions (exp: - 27% vs. ctrl: - 19%, BF01 = 4.7), suggesting a dose-independent effect of motor inhibition on self-reported consumption. Our collective results corroborate the robustness and large size of the devaluation effects induced by response inhibition on palatable items, but challenge the assumption of a linear relationship between such effects and the actual consumption of the target items. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 30/03/2021. The protocol, as accepted by the journal, can be found at: https://doi.org/10.17605/OSF.IO/5ESMP .

3D-Printed Pacifier-Shaped Mouthpiece for fMRI-Compatible Gustometers.

Gustometers have made it possible to deliver liquids in functional magnetic resonance imaging (fMRI) settings for decades, and mouthpieces are a critical part of these taste delivery systems. Here, we propose an innovative 3D-printed fMRI mouthpiece inspired by children's pacifiers, allowing human participants to swallow while lying down in an MRI scanner. We used a large sample to validate the effectiveness of our method. The results suggest that the mouthpiece can be used to deliver taste stimuli by showing significant clusters of activation in the insular and piriform cortex, which are regions that have been consistently identified in taste processing. This mouthpiece fulfills several criteria guaranteeing a gustatory stimulus of quality, making the delivery precise and reliable. Moreover, this new pacifier-shaped design is simple and cheap to manufacture, hygienic, comfortable to keep in the mouth, and flexible to use in diverse cases. We hope that this new method will promote and facilitate the study of taste and flavor perception in the context of reward processing in affective neuroscience, and thus, help provide an integrative approach to the study of the emotional nature of rewards.

Exogenous capture of visual spatial attention by olfactory-trigeminal stimuli.

The extent to which a nasal whiff of scent can exogenously orient visual spatial attention remains poorly understood in humans. In a series of seven studies, we investigated the existence of an exogenous capture of visual spatial attention by purely trigeminal (i.e., CO2) and both olfactory and trigeminal stimuli (i.e., eucalyptol). We chose these stimuli because they activate the trigeminal system which can be considered as an alert system and are thus supposedly relevant for the individual, and thus prone to capture attention. We used them as lateralized cues in a variant of a visual spatial cueing paradigm. In valid trials, trigeminal cues and visual targets were presented on the same side whereas in invalid trials they were presented on opposite sides. To characterize the dynamics of the cross-modal attentional capture, we manipulated the interval between the onset of the trigeminal cues and the visual targets (from 580 to 1870 ms). Reaction times in trigeminal valid trials were shorter than all other trials, but only when this interval was around 680 or 1170 ms for CO2 and around 610 ms for eucalyptol. This result reflects that both pure trigeminal and olfactory-trigeminal stimuli can exogenously capture humans' spatial visual attention. We discuss the importance of considering the dynamics of this cross-modal attentional capture.

Is knowledge emotion? The subjective emotional responses to wines depend on level of self-reported expertise and sensitivity to key information about the wine.

Many factors influence emotional responses evoked by wines. Here we assessed how self-reported wine expertise, tasting condition (blind vs. informed) as well as sensitivity to key information about wines (e.g., reputation, price, grape variety) impact the subjective affective responses they evoked. We measured subjective affective responses of high and low in self-reported wine expertise consumers to 8 different wines in a blind tasting and in a tasting when information about the wines was known. After their first tasting session, we asked participants the extent to which they considered specific information when they intended to purchase wine (e.g., reputation, etc.). The more wine consumers high in self-reported expertise paid attention to the wine's reputation, the less they used feelings when tasting wines. In contrast, the more the wine tasters low in self-reported expertise paid attention to the wine's reputation, the more feelings they reported. Moreover, when considering positive and negative feelings separately, it appears that the more participants paid attention to the label, the lower the number of positive terms they tended to mention. Additionally, wine tasters low in self-reported expertise were more inclined to report positive feelings towards the wines in the informed condition and if they were sensitive to wine's reputation. In contrast, wine tasters high in self-reported expertise were less inclined to report positive feelings towards the wines in the informed condition and if they were sensitive to wine's reputation. These results hint at the importance of considering psychological theories of emotion while studying wine-elicited emotions, in particular appraisal theories of emotion.

The COVID-19 may help enlightening how emotional food is.

Olfactory and gustatory stimuli can elicit potent emotional responses and are essential in food perception. Yet, main theories of emotion often under-represent them, and our understanding of affective phenomena relies mostly on experimental studies conducted on visual and auditory stimuli. Although evidence is still accumulating today, recent findings suggest that the COVID-19 is associated with a loss in olfaction and/or taste. Here, I discuss how this unprecedented and uncommon spread of the loss of olfaction and/or taste worldwide may enlighten how emotional both these senses are and how much they influence food perception.

[Diabetes mellitus: impact of affects on self-management skills]. / Diabète sucré: impact des affects sur les compétences d'autogestion.

Diabetes self-management (DSM) is a process based on a series of complex learnings. The conceptualization of the role of the emotional dimensions that underlie and structure this process is critical to better understand why living with diabetes can become a burden. A clinical case illustrates the intertwining of the affective and cognitive dimensions of diabetes burden and its influence on DSM skills. Emotional regulation is a recognized determinant to implement effective and long-term DSM skills as well as access to DSM interventions. In order to improve DSME/S interventions efficacy, the role of emotional dimensions, new technologies and therapeutic advances needs to be considered.

L'autogestion du diabète sucré (AGDM) est un processus basé sur une série d'apprentissages complexes. La conceptualisation du rôle des dimensions affectives qui sous-tendent et structurent ce processus permet d'appréhender différemment le vécu des patients avec un diabète sucré. Une vignette clinique illustre l'intrication des dimensions affectives et cognitives et les possibles conséquences sur l'AGDM. La régulation des émotions s'avère être un des facteurs déterminants de l'AGDM, tout comme l'accès à des dispositifs d'éducation thérapeutique du patient (ETP). La prise en compte du rôle respectif des dimensions émotionnelles, des nouvelles technologies et des avancées thérapeutiques sur l'AGDM est à considérer pour développer des dispositifs d'ETP performants.

How does the peak-end rule smell? Tracing hedonic experience with odours.

The peak-end rule predicts that retrospective evaluations of affective events heavily depend on their most intense and last moment and imply duration neglect. It was originally proposed for negative experiences such as painful medical procedures. It is unclear, however, to what degree it also applies to positive experiences. Previously, rigorous comparisons between the two domains were limited due to the use of qualitatively different stimuli. Hence, it is not clear if the peak-end rule holds for short positive and negative experiences alike. To address these questions in a genuinely emotional domain, we conducted two experiments (n = 48 each) in which we used odours as stimuli. Participants repeatedly evaluated continuous odour sequences delivered into their noses via an olfactometer. The sequences differed in valence (positive vs. negative), length (36 vs. 72 s), and trajectory (increasing, decreasing, U-shaped, and inverse U-shaped). Results provide evidence for the peak-end rule for both positive and negative experiences alike. Results further show an overweighting of intense negative experiences for sequences that contain both pleasant and unpleasant episodes but provide little evidence for an effect of the trajectory manipulation.

Supra-Additive Effects of Combining Fat and Carbohydrate on Food Reward.

Post-ingestive signals conveying information about the nutritive properties of food are critical for regulating ingestive behavior. Here, using an auction task concomitant to fMRI scanning, we demonstrate that participants are willing to pay more for fat + carbohydrate compared with equally familiar, liked, and caloric fat or carbohydrate foods and that this potentiated reward is associated with response in areas critical for reward valuation, including the dorsal striatum and mediodorsal thalamus. We also show that individuals are better able to estimate the energy density of fat compared with carbohydrate and fat + carbohydrate foods, an effect associated with functional connectivity between visual (fusiform gyrus) and valuation (ventromedial prefrontal cortex) areas. These results provide the first demonstration that foods high in fat and carbohydrate are, calorie for calorie, valued more than foods containing only fat or carbohydrate and that this effect is associated with greater recruitment of central reward circuits.

[Food reward circuitry in obese patients]. / Circuits de la récompense alimentaire chez les patients obèses.

Besides hormonal regulation of appetite and satiety, food intake depends on the activity of certain brain systems. Functional imaging studies are useful to better understand this central regulation of energy intake. Obesity is associated with increased brain responses to food stimuli at the level of the reward system. More specifically, studies have shown in obese individuals an increased motivation to obtain food reward as well as a decrease in pleasure during its actual consumption. Food consumption may be, in some instances, comparable to addiction, and be reflected by irresistible cravings for certain foods.

Hormis les mécanismes hormonaux de la régulation de l'appétit et de la satiété, la consommation alimentaire est également contrôlée par certains circuits cérébraux. Cette régulation centrale commence à être mieux étudiée grâce à l'imagerie fonctionnelle. L'obésité est associée à des réponses cérébrales accrues à des stimuli associés à de la nourriture au niveau du circuit de récompense. Plus spécifiquement, les études ont permis de mettre en évidence que les individus obèses avaient une motivation élevée pour obtenir une récompense alimentaire tout en ayant une diminution du plaisir lors de la consommation de celle-ci. De plus, la consommation alimentaire pourrait être, dans certains cas, comparable à l'addiction et se manifester par des envies irrésistibles de consommer certains aliments.

Circadian anosmia: A rare clinical presentation.

We report the case of a 27-year-old female who presented with a peculiar story of anosmia fluctuating in a circadian manner. Olfactory function appeared an hour after breakfast, was normal during daytime, and disappeared in the early evening. Imaging confirmed chronic rhinosinusitis (CRS). Initial systemic, followed by topical steroid treatment, rapidly and sustainably reversed this condition. The olfactory fluctuation paralleled the endogenous steroid production. This suggests that slight congestion changes in a chronically inflamed nasal mucosa may have been sufficient to induce this circadian anosmia. The importance of identifying fluctuation of olfactory function as a sign of CRS is emphasized and discussed. Laryngoscope, 128:1537-1539, 2018.

To What Extent Memory Could Contribute to Impaired Food Valuation and Choices in Obesity?

Obesity is associated with a diverse array of cognitive and affective deficits, among which impairments in food valuation and choices have received increasing attention. The neural underpinnings of such impairments, however, remain poorly understood, partly because a complete understanding of these processes under normal conditions has yet to be achieved. A rapidly growing literature on the interaction between memory and decision-making has begun to highlight the integral role of memory in decision making especially in the real world, as well as the role of the hippocampus in supporting flexible decision making. Perhaps not coincidentally, altered memory performances in obesity have been well documented, and the underlying neurobiological bases of these memory alterations have also started to be better described, involving pathologies at the biochemical, cellular, and circuit levels. Despite such correspondence, the link between memory impairments and food valuation/choice deficits in obesity has received little attention. In this article, we first summarize the growing empirical support for the relevance of memory for decision making, focusing on flexible value-based decisions. We then describe converging evidence on different forms of memory impairments accompanying obesity. Building on these findings, we formulate a general neuropsychological framework and discuss how dysfunctions in the formation and retrieval of memory may interfere with adaptive decision making for food. Finally, we stress the important practical implications of this framework, arguing that memory deficits are likely a significant contributor to suboptimal food purchase and eating behavior exhibited by obese individuals.

Appraising food insecurity.

This commentary focuses on the mechanisms underlying the appraisal of food insecurity. I first describe what appraisal is and why it plays a major role in explaining how different individuals consider food supply as more or less secure. I then describe the potential reciprocal links between appraisal and obesity, based on the well-documented evidence that obesity can cause cognitive deficits.

Swiss identity smells like chocolate: Social identity shapes olfactory judgments.

There is extensive evidence that social identities can shape people's attitudes and behavior, but what about sensory judgments? We examined the possibility that social identity concerns may also shape the judgment of non-social properties-namely, olfactory judgment. In two experiments, we presented Swiss and non-Swiss participants with the odor of chocolate, for which Switzerland is world-famous, and a control odor (popcorn). Swiss participants primed with Swiss identity reported the odor of chocolate (but not popcorn) as more intense than non-Swiss participants (Experiments 1 and 2) and than Swiss participants primed with individual identity or not primed (Experiment 2). The self-reported intensity of chocolate smell tended to increase as identity accessibility increased-but only among Swiss participants (Experiment 1). These results suggest that identity priming can counter-act classic sensory habituation effects, allowing identity-relevant smells to maintain their intensity after repeated presentations. This suggests that social identity dynamically influences sensory judgment. We discuss the potential implications for models of social identity and chemosensory perception.

The anterior medial temporal lobes: Their role in food intake and body weight regulation.

The anterior medial temporal lobes are one of the most studied parts of the brain. Classically, their two main structures - the amygdalae and the hippocampi - have been linked to key cognitive and affective functions, related in particular to learning and memory. Based on abundant evidence, we will argue for an alternative but complementary point of view: they may also play a major role in food intake and body weight regulation. First, an overview is given of early clinical evidence in this line of thought. Subsequently, empirical evidence is presented on how food intake, including in the extreme case of obesity, may relate to amygdalian and hippocampal functioning. The focus is on the amygdala's role in processing the relevance of food stimuli, cue-induced feeding, and stress-induced eating and on the hippocampus' involvement in the use of interoceptive signals of hunger and satiety, as well as memory and inhibitory processes related to food intake. Additionally, an elaboration takes place on possible reciprocal links between food intake, body weight, and amygdala and hippocampus functioning. Finally, issues that seemed particularly critical for future research in the field are discussed.

Sensitivity of Physiological Emotional Measures to Odors Depends on the Product and the Pleasantness Ranges Used.

Emotions are characterized by synchronized changes in several components of an organism. Among them, physiological variations provide energy support for the expression of approach/avoid action tendencies induced by relevant stimuli, while self-reported subjective pleasantness feelings integrate all other emotional components and are plastic. Consequently, emotional responses evoked by odors should be highly differentiated when they are linked to different functions of olfaction (e.g., avoiding environmental hazards). As this differentiation has been observed for contrasted odors (very pleasant or unpleasant), we questioned whether subjective and physiological emotional response indicators could still disentangle subtle affective variations when no clear functional distinction is made (mildly pleasant or unpleasant fragrances). Here, we compared the sensitivity of behavioral and physiological [respiration, skin conductance, facial electromyography (EMG), and heart rate] indicators in differentiating odor-elicited emotions in two situations: when a wide range of odor families was presented (e.g., fruity, animal), covering different functional meanings; or in response to a restricted range of products in one particular family (fragrances). Results show clear differences in physiological indicators to odors that display a wide range of reported pleasantness, but these differences almost entirely vanish when fragrances are used even though their subjective pleasantness still differed. Taken together, these results provide valuable information concerning the ability of classic verbal and psychophysiological measures to investigate subtle differences in emotional reactions to a restricted range of similar olfactory stimuli.

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

Sniffing, which is the active sampling of olfactory information through the nasal cavity, is part of the olfactory percept. It is influenced by stimulus properties, affects how an odor is perceived, and is sufficient (without an odor being present) to activate the olfactory cortex. However, many aspects of the affective correlates of sniffing behavior remain unclear, in particular the modulation of volume and duration as a function of odor hedonics. The present study used a wide range of odorants with contrasted hedonic valence to test: (1) which psychophysical function best describes the relationship between sniffing characteristics and odor hedonics (e.g., linear, or polynomial); (2) whether sniffing characteristics are sensitive to more subtle variations in pleasantness than simple pleasant-unpleasant contrast; (3) how sensitive sniffing is to other perceptual dimensions of odors such as odor familiarity or edibility; and (4) whether the sniffing/hedonic valence relationship is valid in other populations than young adults, such as the elderly. Four experiments were conducted, using 16-48 odorants each, and recruiting a total of 102 participants, including a group of elderly people. Results of the four experiments were very consistent in showing that sniffing was sensitive to subtle variations in unpleasantness but not to subtle variations in pleasantness, and that, the more unpleasant the odor, the more limited the spontaneous sampling of olfactory information through the nasal cavity (smaller volume, shorter duration). This also applied, although to a lesser extent, to elderly participants. Relationships between sniffing and other perceptual dimensions (familiarity, edibility) were less clear. It was concluded that sniffing behavior might be involved in adaptive responses protecting the subject from possibly harmful substances.