'Liking' and 'wanting' food rewards: brain substrates and roles in eating disorders

Control of motivation for sucrose in the paraventricular hypothalamic nucleus by dynorphin peptides and the kappa opioid receptor

The dynorphin peptides are the endogenous ligands for the kappa opioid receptor (KOR) and regulate food intake. Administration of dynorphin-A1-13 (DYN) in the paraventricular hypothalamic nucleus (PVN) increases palatable food intake, and this effect is blocked by co-administration of the orexin-A neuropeptide, which is co-released with DYN in PVN from neurons located in the lateral hypothalamus. While PVN administration of DYN increases palatable food intake, whether it increases food-seeking behaviors has yet to be examined. We tested the effects of DYN and norBNI (a KOR antagonist) on the seeking and consumption of sucrose using a progressive ratio (PR) and demand curve (DC) tasks. In PVN, DYN did not alter the sucrose breaking point (BP) in the PR task nor the elasticity or intensity of demand for sucrose in the DC task. Still, DYN reduced the delay in obtaining sucrose and increased licks during sucrose intake in the PR task, irrespective of the co-administration of orexin-A. In PVN, norBNI increased the delay in obtaining sucrose and reduced licks during sucrose intake in the PR task while increasing elasticity without altering intensity of demand in the DC task. However, subcutaneous norBNI reduced the BP for sucrose and increased the delay in obtaining sucrose in the PR task while reducing the elasticity of demand. Together, these data show different effects of systemic and PVN blockade of KOR on food-seeking, consummatory behaviors, and incentive motivation for sucrose and suggest that KOR activity in PVN is necessary but not sufficient to drive seeking behaviors for palatable food.

Why creatives don't find the oddball odd: Neural and psychological evidence for atypical salience processing

Creativity has previously been linked with various attentional phenomena, including unfocused or broad attention. Although this has typically been interpreted through an executive functioning framework, such phenomena may also arise from atypical incentive salience processing. Across two studies, we examine this hypothesis both neurally and psychologically. First we examine the relationship between figural creativity and event-related potentials during an audio-visual oddball task, finding that rater creativity of drawings is associated with a diminished P300 response at midline electrodes, while abstractness and elaborateness of the drawings is associated with an altered distribution of the P300 over posterior electrodes. These findings support the notion that creativity may involve an atypical attribution of salience to prominent information. We further explore the incentive salience hypothesis by examining relationships between creativity and a psychological indicator of incentive salience captured by participants' ratings of enjoyment (liking) and their motivation to pursue (wanting) diverse real world rewards, as well as their positive spontaneous thoughts about those rewards. Here we find enhanced motivation to pursue activities as well as a reduced relationship between the overall tendency to enjoy rewards and the tendency to pursue them. Collectively, these findings indicate that creativity may be associated with atypical allocation of attentional and motivational resources to novel and rewarding information, potentially allowing more types of information access to attentional resources and motivating more diverse behaviors. We discuss the possibility that salience attribution in creatives may be less dependent on task-relevance or hedonic pleasure, and suggest that atypical salience attribution may represent a trait-like feature of creativity.

Self-reported food liking and wanting: A factor analytic study of ratings across 49 consecutive days

Reward responses to food are thought to play an important role in highly palatable food overconsumption. In animal models, food reward responses can be decoupled into unique "liking" (in the moment enjoyment) and "wanting" (motivation/craving) components. However, research on liking and wanting has been hampered by uncertainty regarding whether liking and wanting can be reliably separated in humans. We used factor analysis to test whether ratings of liking and wanting could be empirically separated in women assessed across 49 consecutive days. Female participants (N = 688; ages 15-30) from the Michigan State University Twin Registry reported liking and wanting of foods consumed that day, and wanting of foods not consumed that day, separately for sweets (e.g., cookies), fast food (e.g., French fries), carbohydrates (e.g., bread), and whole foods (fruit, plain chicken) each evening for 49 consecutive days. We examined both average levels and daily levels of liking/wanting across the 49-day period that captured individual differences in liking/wanting over time. Across both types of analyses, liking and wanting for foods that were eaten formed a single factor rather than separate, dissociable factors, while wanting of foods not eaten formed an independent factor. At the daily level, a liking/wanting factor emerged for each individual food category (e.g., liking/wanting sweets), whereas in average analyses, a single factor emerged that collapsed across all food types (i.e., liking/wanting of all foods). Results suggest individuals have difficulty distinguishing between liking and wanting of foods they have eaten on that day but may be able to more reliably separate wanting of foods they have not consumed.

Neural correlates of chocolate brand preference: A functional MRI study

BACKGROUND AND PURPOSE

Preferences can be developed for, or against, specific brands and services. Using two functional magnetic resonance imaging (fMRI) experiments, this study investigated two dissociable aspects of reward processing, craving and liking, in chocolate lovers. The goal was to further delineate the neural basis supporting branding effects using familiar chocolate (FC) and unfamiliar chocolate (UC) brand images.

METHODS

In the first experiment, subjects rated their subjective craving and liking on a scale of 1-5 (weak-strong) for each FC and UC image. In the second experiment, they performed a choice task between FC and UC images.

RESULTS

Both the craving and liking ratings were significantly greater for FC and were differentially correlated with choice behavior. Craving ratings predicted greater preference for UC, and liking ratings predicted greater preference for FC. A contrast of neural activity for UC versus FC choice trials revealed significantly greater activation for UC choices in the bilateral inferior frontal gyrus and right caudate head. Response times for the FC images were faster than UC images; fMRI activity in the ventromedial prefrontal cortex was significantly correlated with response times during FC trials, but not UC trials. These correlations were significantly different from each other at the group level.

CONCLUSIONS

The choices for branded chocolate products are driven by higher subjective reward ratings and lower neural processing demands.

Clean-label products: Factors affecting liking and acceptability by Portuguese older adults

Consumers are preferring more "natural" foods, made of "healthier" and "familiar" components - the "clean-label" trend. As the population ages, understanding the older adult consumer segment becomes increasingly important. This study aims to identify the factors influencing the acceptability and liking of clean-label products in older adults living in the community. A convenience sample of 100 older adults was used for this cross-sectional study. Socio-demographic data, health status, independence level, lifestyle characteristics, nutritional status, and food and nutrient intake data were collected. The acceptability and liking for clean-label products comprised two parts: Sensory analysis with overall liking evaluation of three pairs of products, using a 9-point hedonic scale and free comments; Willingness to eat and preference assessment of nine pairs of products using the Food Action scale and a simple preference test. The participants were 80% female with a mean age of 75 years old. The overall liking for clean-label versions of cookies and mayonnaise was lower than for traditional versions. However, participants were more willing to eat the clean-label versions of products, particularly ham and yogurt. Most of the participants would prefer buying the clean-label version of all nine pairs of products, especially for ham, loaf bread, sausages, and yogurt. In sum, older adults living in the community exhibit a lower liking but, a greater willingness to eat and a higher preference for buying clean-label products. Older adults who favor clean-label products have higher levels of education and are reported to have a more adequate diet.

The computational structure of consummatory anhedonia

Anhedonia is a reduction in enjoyment, motivation, or interest. It is common across mental health disorders and a harbinger of poor treatment outcomes. The enjoyment aspect, termed 'consummatory anhedonia', in particular poses fundamental questions about how the brain constructs rewards: what processes determine how intensely a reward is experienced? Here, we outline limitations of existing computational conceptualisations of consummatory anhedonia. We then suggest a richer reinforcement learning (RL) account of consummatory anhedonia with a reconceptualisation of subjective hedonic experience in terms of goal progress. This accounts qualitatively for the impact of stress, dysfunctional cognitions, and maladaptive beliefs on hedonic experience. The model also offers new views on the treatments for anhedonia.

Food insecurity, poor diet, and metabolic measures: The roles of stress and cortisol

Food insecurity is highly prevalent and linked to poorer diet and worse metabolic outcomes. Food insecurity can be stressful, and could elicit chronic psychological and physiological stress. In this study, we tested whether stress could be used to identify those at highest risk for worse diet and metabolic measures from food insecurity. Specifically, we hypothesized that cortisol (a physiological marker of stress) and perceived psychological stress would amplify the link between food insecurity and hyperpalatable food intake as well as metabolic measures. In a sample of 624 Black and White women aged 36-43 who participated in the NHLBI Growth and Health Study's midlife assessment, we assessed associations between food insecurity with hyperpalatable food intake (high fat + high sodium foods; high fat + high sugar foods; and high carbohydrate + high sodium foods), and metabolic measures (fasting glucose, insulin resistance, and waist circumference). We found that food insecurity was associated with higher levels of perceived stress (R2 = 0.09), and greater intake of high fat + high sugar (hyperpalatable) foods (R2 = 0.03). In those with higher cumulative cortisol (as indexed by hair cortisol), food insecurity was associated with higher levels of fasting glucose. Neither cortisol nor perceived stress moderated any other relationships, and neither variable functioned as a mediator in sensitivity analyses. Given these largely null findings, further research is needed to understand the role stress plays in the chronic health burdens of food insecurity.

Modifying biased attention towards food stimuli in binge eating disorder: A multi-session training study

Individuals with binge eating disorder (BED) exhibit a biased attention towards food stimuli. Against this backdrop, the present study with pre-registered design (ID: DRKS00012984) tested whether (a) a training designed to reduce attentional food processing indeed modifies this bias, (b) this reduction is evident in several measures of food-related attention and (c) this is associated with reductions in craving, binge frequency over the past 28 days and calories eaten in a laboratory based bogus taste test. Individuals with BED were randomly allocated to four sessions of either an attentional bias modification training (ABMT; n = 39) or a comparable no-modification control training (CT; n = 27). In all measures assessed via eye-tracking - dwell time bias, dwell time bias variability and first fixation bias - food-related bias decreased in the ABMT relative to the CT. Against our hypothesis, no differential between-group effects were found for reaction time (RT) bias and its variability as well as for calories consumed in a bogus taste test. By contrast, reductions in binge frequency and subjective craving were found for both groups. Taken together, the tendency to preferentially process food seems a modifiable phenomenon in individuals with BED. However, modifying this selective viewing pattern does not seem a prerequisite for a successful reduction of binge frequency.

Octopamine integrates the status of internal energy supply into the formation of food-related memories

The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.

Altered neuronal response to visual food stimuli in adolescents undergoing chronic sleep restriction

STUDY OBJECTIVES

Poor sleep in adolescents can increase the risk of obesity, possibly due to changes in dietary patterns. Prior neuroimaging evidence, mostly in adults, suggests that lacking sleep results in increased response to food cues in reward-processing brain regions. Needed is a clarification of the mechanisms by which food reward processing is altered by the kind of chronic sleep restriction (SR) typically experienced by adolescents. This study aimed to elucidate the impact of sleep duration on response to visual food stimuli in healthy adolescents using functional neuroimaging, hypothesizing increased reward processing response after SR compared to a well-rested condition.

METHODS

Thirty-nine healthy adolescents, 14-17 years old, completed a 3-week protocol: (1) sleep phase stabilization; (2) SR (~6.5 h nightly); and (3) healthy sleep (HS) duration (~9 h nightly). Participants underwent functional MRI while performing a visual food paradigm. Contrasts of food versus nonfood responses were compared within-subject between conditions of SR and HS.

RESULTS

Under SR, there was a greater response to food stimuli compared to HS in a voxel cluster including the left ventral tegmental area and substantia nigra. No change in food appeal rating due to the sleep manipulation was detected.

CONCLUSIONS

Outcomes of this study suggest that SR, as commonly experienced by healthy adolescents, results in the elevated dopaminergic drive of the reward network that may augment motivation to seek food in the context of individual food appeal and inhibitory profiles. Countermeasures that reduce food salience could include promoting consistent HS habits.

NMDA- and 6-OHDA-induced Lesions in the Nucleus Accumbens Differently Affect Maternal and Infanticidal Behavior in Pup-naïve Female and Male Mice

Virgin and pups-naïve female and male adult mice display two opposite responses when they are exposed to pups for the first time. While females generally take care of the pups, males attack them. Since the nucleus accumbens (NA), and its dopaminergic modulation, is critical in integrating information and processing reward and aversion, we investigated if NMDA- and 6-OHDA-induced lesions, damaging mostly NA output and dopaminergic inputs respectively, affected female maternal behavior (MB) or male infanticidal behavior (IB) in mice. Our results revealed minor or no effects of both smaller and larger NMDA-induced lesions in MB and IB. On the other hand, while 6-OHDA-induced lesions in females reduced the incidence of full MB (12.5% 6-OHDA vs. 85.7% SHAM) increasing the latency to retrieve the pups, those lesions did not affect IB in males. There were no differences in locomotor and exploratory activity between the lesioned- and SHAM- females. Despite those lesions did not induce any major effect on IB, NMDA-lesioned males spent less time in the central area of an open field, while dopaminergic-lesioned males showed reduced number of rearing and peripheral crosses. The current study shows that an intact NA is not necessary for the expression of MB and IB. However, dopaminergic inputs to NA play different role in MB and IB. While damaging dopaminergic terminals into the NA did not affect IB, it clearly delayed the more flexible and rewarding expression of parental behavior.

Measuring Pleasure from Food-Validation of the Food Pleasure Scale by Multiple Techniques and Mixed Methods

The development of scales and questionnaires to assess pleasure perception has gained prominence, particularly for evaluating anhedonia in mental disorders. The Food Pleasure Scale is a comprehensive tool exclusively dedicated to measuring pleasure perception from food and food-related experiences. This study aimed to evaluate the face validity and consistency reliability of the Food Pleasure Scale using a mixed methods approach. Twenty-two participants completed the Food Pleasure Scale questionnaire and participated in in-depth interviews to understand their interpretation of the scale items. The interview data underwent thematic analysis, and the quantitative survey data was compared to the qualitative interview responses. Results indicated a high level of understanding of all items in the Food Pleasure Scale, confirming its face validity and applicability. The mixed methods approach supported the consistency reliability, showing consistency between quantitative measures and participants' explicit and implicit expressions of food pleasure. Furthermore, the study revealed a novel aspect related to food pleasure: the concept of "making an effort". Overall, this study highlights the comprehensibility, validity, and potential of the Food Pleasure Scale in consumer studies. It effectively captures the subjective experience of pleasure derived from food and food-related encounters, making it a valuable tool for further research in this domain.

Neurocognitive reward processes measured via event-related potentials are associated with binge-eating disorder diagnosis and ecologically-assessed behavior

Altered reward processing has been implicated in the onset and maintenance of binge-eating disorder (BED). However, it is unclear which precise neurocognitive reward processes may contribute to BED. In the present study, 40 individuals with BED and 40 age-, sex-, and BMI-matched controls completed a reward (incentive delay) task while their neural activity was recorded using electroencephalography (EEG). Individuals with BED also completed a 10-day ecological momentary assessment (EMA) protocol assessing binge-eating behavior in the natural environment. Event-related potential (ERP) analysis of the EEG indicated that individuals with BED had stronger anticipatory (CNV) and outcome-related (RewP) neural reward activity to food and monetary rewards, compared to controls. However, within the BED group, greater frequency of binge eating during the EMA protocol was associated with stronger anticipatory (CNV) but weaker outcome-related (RewP) neural reward activity. These associations within the BED group were unique to food, and not monetary, rewards. Although preliminary, these results suggest that both anticipatory ("wanting") and outcome ("liking") reward processes may be generally amplified in BED. However, they also suggest that among individuals with BED, disorder severity may be associated with increased anticipatory reward processes ("wanting"), but relatively decreased reward-outcome processing ("liking"), of food rewards specifically.

From active affordance to active inference: vertical integration of cognition in the cerebral cortex through dual subcortical control systems

In previous papers, we proposed that the dorsal attention system's top-down control is regulated by the dorsal division of the limbic system, providing a feedforward or impulsive form of control generating expectancies during active inference. In contrast, we proposed that the ventral attention system is regulated by the ventral limbic division, regulating feedback constraints and error-correction for active inference within the neocortical hierarchy. Here, we propose that these forms of cognitive control reflect vertical integration of subcortical arousal control systems that evolved for specific forms of behavior control. The feedforward impetus to action is regulated by phasic arousal, mediated by lemnothalamic projections from the reticular activating system of the lower brainstem, and then elaborated by the hippocampus and dorsal limbic division. In contrast, feedback constraint-based on environmental requirements-is regulated by the tonic activation furnished by collothalamic projections from the midbrain arousal control centers, and then sustained and elaborated by the amygdala, basal ganglia, and ventral limbic division. In an evolutionary-developmental analysis, understanding these differing forms of active affordance-for arousal and motor control within the subcortical vertebrate neuraxis-may help explain the evolution of active inference regulating the cognition of expectancy and error-correction within the mammalian 6-layered neocortex.

You eye what you eat: BMI, consumption patterns, and dieting status predict temporal attentional bias to food-associated images

People know that overconsumption of high-fat high-sugar (HFHS) foods have negative consequences for physical and cognitive wellbeing but continue to consume these foods in excess, leading to recent proposals to model obesity as an addiction disorder. The current experiment tested, in a large undergraduate sample (N = 306), the hypothesis that obesity and overconsumption is linked with an oversensitivity to rewards that drives attentional biases towards foods and food-associated cues. Using a modified emotion-induced blindness task with food-related distractors, we examined the extent to which attentional biases to images of HFHS foods were accounted for by BMI, HFHS food intake, self-reported hunger, time since last meal, diet status, food preferences, and attentional control. We also examined whether the same individual differences predicted attentional priority to cues that have a learned association with HFHS foods (i.e., images of food logos). Contrary to our predictions, higher BMI predicted less attentional priority for images of food and food logos. At the same time, increased consumption of HFHS foods predicted increased attentional priority for food images, whereas dieting predicted increased attentional priority for food logo images. Our results suggest that different people may preferentially attend to food versus food logo imagery based on their relationships with food. More broadly, our results support the theoretical perspective that attentional biases to food-associated stimuli can be affected by various competing, state-related factors.

Neurohormonal response patterns to hunger, satiation, and postprandial fullness in normal weight, anorexia nervosa, and obesity

BACKGROUND

Food intake is regulated by homeostatic and hedonic systems that interact in a complex neuro-hormonal network. Dysregulation in energy intake can lead to obesity (OB) or anorexia nervosa (AN). However, little is known about the neurohormonal response patterns to food intake in normal weight (NW), OB, and AN.

MATERIAL & METHODS

During an ad libitum nutrient drink (Ensure®) test (NDT), participants underwent three pseudo-continuous arterial spin labeling (pCASL) MRI scans. The first scan was performed before starting the NDT after a > 12 h overnight fast (Hunger), the second after reaching maximal fullness (Satiation), and the third 30-min after satiation (postprandial fullness). We measured blood levels of ghrelin, cholecystokinin (CCK), glucagon-like peptide (GLP-1), and peptide YY (PYY) with every pCASL-MRI scan. Semiquantitative cerebral blood flow (CBF) maps in mL/100 gr brain/min were calculated and normalized (nCBF) with the CBF in the frontoparietal white matter. The hypothalamus (HT), nucleus accumbens [NAc] and dorsal striatum [DS] were selected as regions of interest (ROIs).

RESULTS

A total of 53 participants, 7 with AN, 17 with NW (body-mass index [BMI] 18.5-24.9 kg/m2 ), and 29 with OB (BMI ≥30 kg/m2 ) completed the study. The NW group had a progressive decrease in all five ROIs during the three stages of food intake (hunger, satiation, and post-prandial fullness). In contrast, participants with OB showed a minimal change from hunger to postprandial fullness in all five ROIs. The AN group had a sustained nCBF in the HT and DS, from hunger to satiation, with a subsequent decrease in nCBF from satiation to postprandial fullness. All three groups had similar hormonal response patterns with a decrease in ghrelin, an increase in GLP-1 and PYY, and no change in CCK.

CONCLUSION

Conditions of regulated (NW) and dysregulated (OB and AN) energy intake are associated with distinctive neurohormonal activity patterns in response to hunger, satiation, and postprandial fullness.

Accumbal μ-opioid receptors and salt taste-elicited hedonic responses in a rodent model of prenatal adversity, and their correlates using human functional genomics

Prenatal adversity is associated with behavioral obesogenic features such as preference for palatable foods. Salt appetite may play a role in the development of adiposity and its consequences in individuals exposed to prenatal adversity, and sodium consumption involves individual differences in accumbal µ-opioid receptors function. We investigated the hedonic responses to salt and the levels of µ-opioid receptors and tyrosine hydroxylase in the nucleus accumbens (Nacc) of pups from an animal model of prenatal dietary restriction. In children, we evaluated the interaction between fetal growth and the genetic background associated with the accumbal µ-opioid receptor gene (OPRM1) expression on sodium consumption during a snack test. Sprague-Dawley dams were randomly allocated from pregnancy day 10 to receive an ad libitum (Adlib) or a 50% restricted (FR) diet. The pups' hedonic responses to a salt solution (NaCl 2%) or water were evaluated on the first day of life. FR and Adlib pups differ in their hedonic responses to salt, and there were decreased levels of accumbal µ-opioid and p-µ-opioid receptors in FR pups. In humans, a test meal and genotyping from buccal epithelial cells were performed in 270 children (38 intrauterine growth restricted-IUGR) at 4 years old from a Canadian prospective cohort (MAVAN). The OPRM1 genetic score predicted the sodium intake in IUGR children, but not in controls. The identification of mechanisms involved in the brain response to prenatal adversity and its consequences in behavioral phenotypes and risk for chronic diseases later in life is important for preventive and therapeutic purposes.

Soft and energy drinks consumption and associated factors in Saudi adults: a national cross-sectional study

Introduction

The consumption of soft and energy drinks poses a significant risk for non-communicable diseases, such as diabetes and heart disease. Studies in Saudi Arabia have reported elevated consumption of soft/energy drinks, but nation-wide data is not available. Therefore, this study aims to explore the prevalence of soft and energy drinks consumption and its associated factors among a representative sample of Saudi adults.

Methods

The present research is a secondary data analysis of the 2021 Sharik Diet and Health National Survey (SDHNS). Current analysis used data on socio-demographics, anthropometrics, physical activity, and soft and energy drink consumption. The frequency of soft and energy drinks consumption is assessed on a weekly basis.

Results

Of the 5,194 Saudi adults, 3,928 were analyzed. Overall, 67% consumed soft drinks weekly, while 30% consumed energy drinks weekly. In multiple logistic regression, consumption of either soft drinks or energy drinks was associated with males, a younger age, lower income, and lower physical activity. Individuals with overweight or obesity were less likely to consume energy drinks [OR (95%CI): 0.83 (0.71, 0.99) and 0.73 (0.60, 0.90), respectively] than those with healthy weight. However, education level was not associated with either soft or energy drink consumption. These findings highlight the need for targeted interventions designed to reduce soft and energy drinks consumption in Saudi adults.

The cerebellum plays more than one role in the dysregulation of appetite: Review of structural evidence from typical and eating disorder populations

OBJECTIVE

Dysregulated appetite control is characteristic of anorexia nervosa (AN), bulimia nervosa (BN), and obesity (OB). Studies using a broad range of methods suggest the cerebellum plays an important role in aspects of weight and appetite control, and is implicated in both AN and OB by reports of aberrant gray matter volume (GMV) compared to nonclinical populations. As functions of the cerebellum are anatomically segregated, specific localization of aberrant anatomy may indicate the mechanisms of its relationship with weight and appetite in different states. We sought to determine if there were consistencies in regions of cerebellar GMV changes in AN/BN and OB, as well as across normative (NOR) variation.

METHOD

Systematic review and meta-analysis using GingerALE.

RESULTS

Twenty-six publications were identified as either case-control studies (nOB  = 277; nAN/BN  = 510) or regressed weight from NOR data against brain volume (total n = 3830). AN/BN and OB analyses both showed consistently decreased GMV within Crus I and Lobule VI, but volume reduction was bilateral for AN/BN and unilateral for OB. Analysis of the NOR data set identified a cluster in right posterior lobe that overlapped with AN/BN cerebellar reduction. Sensitivity analyses indicated robust repeatability for NOR and AN/BN cohorts, but found OB-specific heterogeneity.

DISCUSSION

Findings suggest that more than one area of the cerebellum is involved in control of eating behavior and may be differentially affected in normal variation and pathological conditions. Specifically, we hypothesize an association with sensorimotor and emotional learning via Lobule VI in AN/BN, and executive function via Crus I in OB.

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.

What Is Food Noise? A Conceptual Model of Food Cue Reactivity

As GLP-1 receptor agonists, like semaglutide, emerge as effective treatments for weight management, anecdotal reports from patients and clinicians alike point to a reduction in what has been colloquially termed "food noise", as patients report experiencing less rumination and obsessive preoccupation about food. In this narrative review, we discuss concepts used in studies to investigate human eating behavior that can help elucidate and define food noise, particularly food cue reactivity. We propose a conceptual model that summarizes the main factors that have been shown to determine the magnitude of the reactivity elicited by external and internal food cues and how these factors can affect short- and long-term behavioral and clinical outcomes. By integrating key research conducted in this field, the Cue-Influencer-Reactivity-Outcome (CIRO) model of food cue reactivity provides a framework that can be used in future research to design studies and interpret findings related to food noise and food cue reactivity.

Relationship between attentional bias and stimulus control: An observational study of real-world eating patterns

BACKGROUND

Attentional bias towards food related stimuli has been proposed as a potential target for dieting intervention, however the evidence supporting a relationship between attentional bias and food intake is mixed. Theory holds that food related attentional bias should be positively associated with measures of stimulus-controlled eating, and that implicit processes such as impulsivity moderate this association. The aim of the present study was to examine whether the proposed relationship between food-related attentional bias and stimulus control exists, and whether it is moderated by impulsivity.

METHOD

A community sample of 68 participants completed a food-related attentional bias task and impulsiveness scale during a laboratory visit, after which they recorded their real-world eating in real-time over 14 days using Ecological Momentary Assessment (EMA). During this time, participants also responded to 4-5 randomly timed assessments per day. Food outlet presence (e.g., fast food restaurants, cafes, corner stores etc.) was assessed during both eating and non-eating assessments. EMA data was then used to determine levels of stimulus controlled eating for each participant.

FINDINGS

Substantial variation was seen in both our measure of both food-related attentional bias (Range: 33.9 to 80.0) and in the degree to which the participant's eating could be categorised as being under stimulus control (Range: 0.50 to 0.93). However, food-related attentional bias scores were not a significant independent predictor of stimulus control and nor was this relationship moderated by impulsivity.

CONCLUSION

Contrary to theoretical predictions, we found no evidence that of an association between attentional bias, impulsivity, and stimulus control. More work is needed to better understand the implicit processes underlying eating behaviour in the real-world.

Neurocognitive predictors of food memory in healthy adults - A preregistered analysis

Memory processes have long been known to determine food choices (Rozin & Zellner, 1985) but recognition memory of food and its cognitive, homeostatic and neuroanatomical predictors are still largely understudied. 60 healthy, overweight, non-restrictive eating adults (20 females) took part in a food wanting and subsequent food recognition and lure discrimination task at four time points after a standardized breakfast shake. With advanced tractography of 3 T diffusion-weighted imaging data, we investigated the influence of the uncinate fasciculus' (UF) brain microstructure on the interplay of food wanting and memory processes. The analysis was preregistered in detail and conducted with Bayesian multilevel regression modeling. Target recognition (d') and lure discrimination (LDI) performance of food tended to be higher than of art images while single image food memory accuracy evidently dominated art memory. On this single item level, wanting enhanced recognition accuracy and caloric content enhanced food memory accuracy. The enhancement by reward anticipation was most pronounced during memory encoding. Subjective hunger level did not predict performance on the memory task. The microstructure of the UF did neither evidently affect memory performance outcomes nor moderate the wanting enhancement of the recognition accuracy. Interestingly, female participants outperformed males on the memory task, and individuals with stronger neuroticism showed poorer memory performance. We shed light on to date understudied processes in food decision-making: reward anticipation influenced recognition accuracy and food memory was enhanced by higher caloric content, both effects might shape food decisions. Our findings indicate that brain microstructure does not affect food decision processes in adult populations with overweight. We suggest extending investigation of this interplay to brain activity as well as to populations with eating behaviour disorders.

Exploring the influence of circulating endocannabinoids and nucleus accumbens functional connectivity on anorexia nervosa severity

Anorexia nervosa (AN) is a severe psychiatric disorder characterized by a harmful persistence of self-imposed starvation resulting in significant weight loss. Research suggests that alterations in the nucleus accumbens (NAcc) and circulating endocannabinoids (eCBs), such as anandamide (AEA) and 2-arachidonoylglycerol (2-AG), may contribute to increased severity and maladaptive behaviors in AN, warranting an examination of the interplay between central reward circuitry and eCBs. For this purpose, we assessed NAcc functional connectivity and circulating AEA and 2-AG concentrations in 18 individuals with AN and 18 healthy controls (HC) to test associations between circulating eCBs, NAcc functional connectivity, and AN severity, as defined by body mass index (BMI). Decreased connectivity was observed between the NAcc and the right insula (NAcc-insula; pFWE < 0.001) and the left supplementary motor area (NAcc-SMA; pFWE < 0.001) in the AN group compared to HC. Reduced NAcc-insula functional connectivity mediated the association between AEA concentrations and BMI in the AN group. However, in HC, NAcc-SMA functional connectivity had a mediating role between AEA concentrations and BMI. Although no significant differences in eCBs concentrations were observed between the groups, our findings provide insights into how the interaction between eCBs and NAcc functional connectivity influences AN severity. Altered NAcc-insula and NAcc-SMA connectivity in AN may impair the integration of interoceptive, somatosensory, and motor planning information related to reward stimuli. Furthermore, the distinct associations between eCBs concentrations and NAcc functional connectivity in AN and HC could have clinical implications for weight maintenance, with eCBs being a potential target for AN treatment.

Effect of body-related information on food attentional bias in women with body weight dissatisfaction

Women with body weight dissatisfaction (BWD) have long-term negative assessments of their body weight, which are often associated with poor eating behavior. In this study, we investigated the effect of body-related information on the food cue processing and attention of women with BWD. Sixty-eight women were recruited and assigned to either a BWD (NPSS-F > 2) (n = 32) or a no body weight dissatisfaction (NBWD) group (NPSS-F < 1) (n = 36). We measured attentional bias to food cues (high- and low-calorie) with a food probe task after exposure to body-related information and recorded eye tracking data. Body-related images were presented prior to a pair of stimulus images (food-neutral or neutral-neutral). Body-related information and food type were repeated measure factors in our study. Our results showed that the first fixation duration bias for high-calorie foods was significantly longer than for low-calorie foods after exposure to overweight cues in the BWD group. Compared with the NBWD group, the BWD group showed longer first fixation duration bias for high-calorie foods after exposure to overweight cues. The direction for high-calorie foods was significantly more often than that for low-calorie foods in the BWD group after exposure to body-related information. Our findings suggest that compared to women with NBWD, women with BWD may be more susceptible to body-related information, resulting in increased attention to high-calorie foods.

Changes in Food Consumption, BMI, and Body Composition in Youth in the US during the COVID-19 Pandemic

Rates of childhood overweight/obesity have risen for decades; however, data show the prevalence increased at a faster rate during the COVID-19 pandemic. Pandemic-associated increases in youth's body mass index (BMI; kg/m2) have been attributed to decreases in reported physical activity; few studies have examined changes in food intake. We therefore examined changes in total energy, nutrient consumption, BMI, BMIz, and adiposity longitudinally over 3 years, comparing healthy youth aged 8-17 years assessed twice prior to the pandemic, to youth seen once before and once during the pandemic. The total energy intake and percent macronutrient consumption were assessed using a standardized, laboratory-based, buffet-style meal. Height and weight were measured and adiposity was collected via dual energy X-ray absorptiometry. Generalized linear model univariate analyses investigated differences between groups. One-hundred-fifteen youth (15.6 + 2.8 years 47.8% female; 54.8% White) from the Washington D.C., Maryland, and Virginia greater metropolitan area participated. In this secondary analysis, neither changes in total energy intake (p = 0.52) nor changes in nutrient consumption were significantly different between the two groups (ps = 0.23-0.83). Likewise, changes in BMI, BMIz, and adiposity (ps = 0.95-0.25) did not differ by group. Further research should investigate food intake and body composition, comparing youth with and without overweight/obesity to better identify those at greatest risk of excess weight gain during the pandemic.

Art Value Creation and Destruction

I present a theory of creative and destructive value state referring to abstract art. Value is a probabilistic state held as a mixture of its expectation and information forces that coexist in a give-and-take relationship. Expectations are driven by the disclosure of novel information about the value state of various events of desire. Each bit of accumulated information contributes to the improvement of perception up to a threshold level, beyond which begin conscious states. The desire to disclose a value state triggers a triadic system of evaluation which uses concepts, observables and approaches. While the triadic valuation mechanisms can be used to assess various commodities, the scope of this work is limited to the case of artworks, in particular abstract paintings. I assume that art value is basically mediated by the interplay between these value state mechanisms of creation and destruction. Expectations in artwork develop attraction by challenging its contemplator to evaluate (predict) its meaning. Once the relevant information, corresponding to its creative expectations, is acquired (and conditioned), emotional states of indifference, disinterest and desensitization develop.

The effect of cognitive load on preference and intensity processing of sweet taste in the brain

Distracted eating can cause overconsumption. Whereas previous work has shown that cognitive load suppresses perceived taste intensity and increases subsequent consumption, the mechanism behind distraction-induced overconsumption remains unclear. To elucidate this, we performed two event-related fMRI experiments that examined how cognitive load affects neural responses and perceived intensity and preferred intensity, respectively, to solutions varying in sweetness. In Experiment 1 (N = 24), participants tasted weak sweet and strong sweet glucose solutions and rated their intensity while we concurrently varied cognitive load using a digit-span task. In Experiment 2 (N = 22), participants tasted five different glucose concentrations under varying cognitive load and then indicated whether they wanted to keep, decrease or increase its sweetness. Participants in Experiment 1 rated strong sweet solutions as less sweet under high compared to low cognitive load, which was accompanied by attenuated activation the right middle insula and bilateral DLPFC. Psychophysiological interaction analyses showed that cognitive load moreover altered connectivity between the middle insula and nucleus accumbens and DLPFC and middle insula while tasting strong sweet solutions. In Experiment 2, cognitive load did not affect participants' preferred sweetness intensity. fMRI results revealed that cognitive load attenuated DLPFC activation for the strongest sweet solutions in the study. In conclusion, our behavioral and neuroimaging results suggest that cognitive load dampens the sensory processing of strong sweet solutions in particular, which may indicate higher competition for attentional resources for strong sweet than weak sweet solutions under high cognitive load. Implications for future research are discussed.

The effects of an 8-week mindful eating intervention on anticipatory reward responses in striatum and midbrain

Introduction

Accumulating evidence suggests that increased neural responses during the anticipation of high-calorie food play an important role in the tendency to overeat. A promising method for counteracting enhanced food anticipation in overeating might be mindfulness-based interventions (MBIs). However, the neural mechanisms by which MBIs can affect food reward anticipation are unclear. In this randomized, actively controlled study, the primary objective was to investigate the effect of an 8-week mindful eating intervention on reward anticipation. We hypothesized that mindful eating would decrease striatal reward anticipation responses. Additionally, responses in the midbrain-from which the reward pathways originate-were explored.

Methods

Using functional magnetic resonance imaging (fMRI), we tested 58 healthy participants with a wide body mass index range (BMI: 19-35 kg/m2), motivated to change their eating behavior. During scanning they performed an incentive delay task, measuring neural reward anticipation responses to caloric and monetary cues before and after 8 weeks of mindful eating or educational cooking (active control).

Results

Compared with the educational cooking intervention, mindful eating affected neural reward anticipation responses, with reduced caloric relative to monetary reward responses. This effect was, however, not seen in the striatum, but only in the midbrain. The secondary objective was to assess temporary and long-lasting (1 year follow-up) intervention effects on self-reported eating behavior and anthropometric measures [BMI, waist circumference, waist-to-hip-ratio (WHR)]. We did not observe effects of the mindful eating intervention on eating behavior. Instead, the control intervention showed temporary beneficial effects on BMI, waist circumference, and diet quality, but not on WHR or self-reported eating behavior, as well as long-lasting increases in knowledge about healthy eating.

Discussion

These results suggest that an 8-week mindful eating intervention may have decreased the relative salience of food cues by affecting midbrain but not striatal reward responses, without necessarily affecting regular eating behavior. However, these exploratory results should be verified in confirmatory research.The primary and secondary objectives of the study were registered in the Dutch Trial Register (NTR): NL4923 (NTR5025).

Hedonic Overeating-Questionnaire: Exploring interactive effects between wanting, liking, and dyscontrol on body mass index

The Hedonic Overeating-Questionnaire is a brief self-report measure for the trait assessment of liking (pleasure to eat; consummatory reward component), wanting (food craving; anticipatory reward component), and dyscontrol (loss of control over eating). In the original validation study, higher scores on each of the three subscales related to higher body mass index (BMI). However, theories on food reward and self-regulation suggest that overeating and obesity may also result from interactions between these aspects. Therefore, we reanalyzed the data of the original, cross-sectional study (N = 2504, 53% female) and explored whether liking, wanting, and dyscontrol scores interactively predicted BMI. Indeed, there was a significant interaction effect Wanting × Dyscontrol on BMI such that higher dyscontrol scores related to higher BMI, particularly at high wanting scores. The other two-way interactions and the three-way interaction were not significant. Results do not support certain theories on food reward (e.g., the incentive-sensitization theory of addiction and its application to obesity), which would suggest an interactive effect between liking and wanting on BMI. However, they do support dual systems models of self-regulation that suggest that overeating and obesity result from an interplay of strong bottom-up impulses (here: wanting) and weak top-down control (here: dyscontrol).

Disentangling the role of NAc D1 and D2 cells in hedonic eating

Overeating is driven by both the hedonic component ('liking') of food, and the motivation ('wanting') to eat it. The nucleus accumbens (NAc) is a key brain center implicated in these processes, but how distinct NAc cell populations encode 'liking' and 'wanting' to shape overconsumption remains unclear. Here, we probed the roles of NAc D1 and D2 cells in these processes using cell-specific recording and optogenetic manipulation in diverse behavioral paradigms that disentangle reward traits of 'liking' and 'wanting' related to food choice and overeating in healthy mice. Medial NAc shell D2 cells encoded experience-dependent development of 'liking', while D1 cells encoded innate 'liking' during the first food taste. Optogenetic control confirmed causal links of D1 and D2 cells to these aspects of 'liking'. In relation to 'wanting', D1 and D2 cells encoded and promoted distinct aspects of food approach: D1 cells interpreted food cues while D2 cells also sustained food-visit-length that facilitates consumption. Finally, at the level of food choice, D1, but not D2, cell activity was sufficient to switch food preference, programming subsequent long-lasting overconsumption. By revealing complementary roles of D1 and D2 cells in consumption, these findings assign neural bases to 'liking' and 'wanting' in a unifying framework of D1 and D2 cell activity.

Neural responses to reward valence and magnitude from pre- to early adolescence

BACKGROUND

Neural activation during reward processing is thought to underlie critical behavioral changes that take place during the transition to adolescence (e.g., learning, risk-taking). Though literature on the neural basis of reward processing in adolescence is booming, important gaps remain. First, more information is needed regarding changes in functional neuroanatomy in early adolescence. Another gap is understanding whether sensitivity to different aspects of the incentive (e.g., magnitude and valence) changes during the transition into adolescence. We used fMRI from a large sample of preadolescent children to characterize neural responses to incentive valence vs. magnitude during anticipation and feedback, and their change over a period of two years.

METHODS

Data were taken from the Adolescent Cognitive and Brain DevelopmentSM (ABCD®) study release 3.0. Children completed the Monetary Incentive Delay task at baseline (ages 9-10) and year 2 follow-up (ages 11-12). Based on data from two sites (N = 491), we identified activation-based Regions of Interest (ROIs; e.g., striatum, prefrontal regions, etc.) that were sensitive to trial type (win $5, win $0.20, neutral, lose $0.20, lose $5) during anticipation and feedback phases. Then, in an independent subsample (N = 1470), we examined whether these ROIs were sensitive to valence and magnitude and whether that sensitivity changed over two years.

RESULTS

Our results show that most ROIs involved in reward processing (including the striatum, prefrontal cortex, and insula) are specialized, i.e., mainly sensitive to either incentive valence or magnitude, and this sensitivity was consistent over a 2-year period. The effect sizes of time and its interactions were significantly smaller (0.002≤η2≤0.02) than the effect size of trial type (0.06≤η2≤0.30). Interestingly, specialization was moderated by reward processing phase but was stable across development. Biological sex and pubertal status differences were few and inconsistent. Developmental changes were mostly evident during success feedback, where neural reactivity increased over time.

CONCLUSIONS

Our results suggest sub-specialization to valence vs. magnitude within many ROIs of the reward circuitry. Additionally, in line with theoretical models of adolescent development, our results suggest that the ability to benefit from success increases from pre- to early adolescence. These findings can inform educators and clinicians and facilitate empirical research of typical and atypical motivational behaviors during a critical time of development.

Attentional bias for high-calorie food cues by the level of hunger and satiety in individuals with binge eating behaviors

Introduction

The abnormal hyperreactivity to food cues in individuals with binge eating behaviors could be regulated by hedonic or reward-based system, overriding the homeostatic system. The aim of the present study was to investigate whether attentional bias for food cues is affected by the level of hunger, maintaining the normal homeostatic system in individuals with binge eating behaviors.

Methods

A total of 116 female participants were recruited and divided into four groups: hungry-binge eating group (BE) (n = 29), satiated BE (n = 29), hungry-control (n = 29), satiated control (n = 29). While participants completed a free-viewing task on high or low-calorie food cues, visual attentional processes were recorded using an eye tracker.

Results

The results revealed that BE group showed longer initial fixation duration toward high-calorie food cues in both hunger and satiety condition in the early stage, whereas the control group showed longer initial fixation duration toward high-calorie food cues only in hunger conditions. Moreover, in the late stage, the BE group stared more at the high-calorie food cue, compared to control group regardless of hunger and satiety.

Discussion

The findings suggest that automatic attentional bias for food cues in individuals with binge eating behaviors occurred without purpose or awareness is not affected by the homeostatic system, while strategic attention is focused on high-calorie food. Therefore, the attentional processing of food cues in binge eating group is regulated by hedonic system rather than homeostatic system, leading to vulnerability to binge eating.

Behavioral dissection of hunger states in Drosophila

Hunger is a motivational drive that promotes feeding, and it can be generated by the physiological need to consume nutrients as well as the hedonic properties of food. Brain circuits and mechanisms that regulate feeding have been described, but which of these contribute to the generation of motive forces that drive feeding is unclear. Here, we describe our first efforts at behaviorally and neuronally distinguishing hedonic from homeostatic hunger states in Drosophila melanogaster and propose that this system can be used as a model to dissect the molecular mechanisms that underlie feeding motivation. We visually identify and quantify behaviors exhibited by hungry flies and find that increased feeding duration is a behavioral signature of hedonic feeding motivation. Using a genetically encoded marker of neuronal activity, we find that the mushroom body (MB) lobes are activated by hedonic food environments, and we use optogenetic inhibition to implicate a dopaminergic neuron cluster (protocerebral anterior medial [PAM]) to α'/β' MB circuit in hedonic feeding motivation. The identification of discrete hunger states in flies and the development of behavioral assays to measure them offers a framework to begin dissecting the molecular and circuit mechanisms that generate motivational states in the brain.

The Effects of Obesity on the Inflammatory, Cardiovascular, and Neurobiological Responses to Exercise in Older Adults

Obesity with advancing age leads to increased health complications that are involved in various complex physiological processes. For example, inflammation is a critical cardiovascular disease risk factor that plays a role in the stages of atherosclerosis in both aging and obesity. Obesity can also induce profound changes to the neural circuitry that regulates food intake and energy homeostasis with advancing age. Here we discuss how obesity in older adults impacts inflammatory, cardiovascular, and neurobiological functions with an emphasis on how exercise mediates each topic. Although obesity is a reversible disorder through lifestyle changes, it is important to note that early interventions are crucial to prevent pathological changes seen in the aging obese population. Lifestyle modifications such as physical activity (including aerobic and resistance training) should be considered as a main intervention to minimize the synergistic effect of obesity on age-related conditions, such as cerebrovascular disease.

Position statement on nutrition therapy for overweight and obesity: nutrition department of the Brazilian association for the study of obesity and metabolic syndrome (ABESO-2022)

Obesity is a chronic disease resulting from multifactorial causes mainly related to lifestyle (sedentary lifestyle, inadequate eating habits) and to other conditions such as genetic, hereditary, psychological, cultural, and ethnic factors. The weight loss process is slow and complex, and involves lifestyle changes with an emphasis on nutritional therapy, physical activity practice, psychological interventions, and pharmacological or surgical treatment. Because the management of obesity is a long-term process, it is essential that the nutritional treatment contributes to the maintenance of the individual's global health. The main diet-related causes associated with excess weight are the high consumption of ultraprocessed foods, which are high in fats, sugars, and have high energy density; increased portion sizes; and low intake of fruits, vegetables, and grains. In addition, some situations negatively interfere with the weight loss process, such as fad diets that involve the belief in superfoods, the use of teas and phytotherapics, or even the avoidance of certain food groups, as has currently been the case for foods that are sources of carbohydrates. Individuals with obesity are often exposed to fad diets and, on a recurring basis, adhere to proposals with promises of quick solutions, which are not supported by the scientific literature. The adoption of a dietary pattern combining foods such as grains, lean meats, low-fat dairy, fruits, and vegetables, associated with an energy deficit, is the nutritional treatment recommended by the main international guidelines. Moreover, an emphasis on behavioral aspects including motivational interviewing and the encouragement for the individual to develop skills will contribute to achieve and maintain a healthy weight. Therefore, this Position Statement was prepared based on the analysis of the main randomized controlled studies and meta-analyses that tested different nutrition interventions for weight loss. Topics in the frontier of knowledge such as gut microbiota, inflammation, and nutritional genomics, as well as the processes involved in weight regain, were included in this document. This Position Statement was prepared by the Nutrition Department of the Brazilian Association for the Study of Obesity and Metabolic Syndrome (ABESO), with the collaboration of dietitians from research and clinical fields with an emphasis on strategies for weight loss.

The organizational role of ovarian hormones during puberty on risk for binge-like eating in rats

Puberty is a high-risk period for the development of dysregulated eating, including binge eating. While risk for binge eating in animals and humans increases in both males and females during puberty, the increased prevalence is significantly greater in females. Emerging data suggest that the organizational effects of gonadal hormones may contribute to the female preponderance of binge eating. In this narrative review, we discuss studies conducted in animals that have examined these organizational effects as well as the neural systems that may serve as intermediary mechanisms. Relatively few studies have been conducted, but data thus far suggest that pubertal estrogens may organize risk for binge eating, potentially by altering key circuits in brain reward pathways. These promising results highlight the need for future studies to directly test organizational effects of pubertal hormones using hormone replacement techniques and circuit-level manipulations that can identify pathways contributing to binge eating across development.

Reduced sensitivity but intact motivation to monetary rewards and reversal learning in obesity

BACKGROUND

Obesity has been linked to altered reward processing but little is known about which components of reward processing including motivation, sensitivity and learning are impaired in obesity. We examined whether obesity compared to healthy weight controls is associated with differences in distinct subdomains of reward processing. To this end, we used two established paradigms, namely the Effort Expenditure for Rewards task (EEfRT) and the Probabilistic Reversal Learning Task (PRLT).

METHODS

30 individuals with obesity (OBS) and 30 healthy weight control subjects (HC) were included in the study. Generalized estimating equation models were used to analyze EEfRT choice behavior. PRLT data was analyzed using both conventional behavioral variables of choices and computational models.

RESULTS

Our findings from the different tasks speak in favor of a hyposensitivity to non-food rewards in obesity. OBS did not make fewer overall hard task selections compared to HC in the EEfRT suggesting generally intact non-food reward motivation. However, in highly rewarding trials (i.e.,trials with high reward magnitude and high reward probability),OBSmadefewer hard task selections compared to normal weight subjects suggesting decreased sensitivity to highly rewarding non-food reinforcers. Hyposensitivity to non-food rewards was also evident in OBS in the PRLT as evidenced by lower win-stay probability compared to HC. Our computational modelling analyses revealed decreased stochasticity but intact reward and punishment learning rates in OBS.

CONCLUSIONS

Our findings provide evidence for intact reward motivation and learning in OBS but lower reward sensitivity which is linked to stochasticity of choices in a non-food context. These findings might provide further insight into the mechanism underlying dysfunctional choices in obesity.

Identification of a GABAergic neural circuit governing leptin signaling deficiency-induced obesity

The hormone leptin is known to robustly suppress food intake by acting upon the leptin receptor (LepR) signaling system residing within the agouti-related protein (AgRP) neurons of the hypothalamus. However, clinical studies indicate that leptin is undesirable as a therapeutic regiment for obesity, which is at least partly attributed to the poorly understood complex secondary structure and key signaling mechanism of the leptin-responsive neural circuit. Here, we show that the LepR-expressing portal neurons send GABAergic projections to a cohort of α3-GABAA receptor expressing neurons within the dorsomedial hypothalamic nucleus (DMH) for the control of leptin-mediated obesity phenotype. We identified the DMH as a key brain region that contributes to the regulation of leptin-mediated feeding. Acute activation of the GABAergic AgRP-DMH circuit promoted food intake and glucose intolerance, while activation of post-synaptic MC4R neurons in the DMH elicited exactly opposite phenotypes. Rapid deletion of LepR from AgRP neurons caused an obesity phenotype which can be rescued by blockage of GABAA receptor in the DMH. Consistent with behavioral results, these DMH neurons displayed suppressed neural activities in response to hunger or hyperglycemia. Furthermore, we identified that α3-GABAA receptor signaling within the DMH exerts potent bi-directional regulation of the central effects of leptin on feeding and body weight. Together, our results demonstrate a novel GABAergic neural circuit governing leptin-mediated feeding and energy balance via a unique α3-GABAA signaling within the secondary leptin-responsive neural circuit, constituting a new avenue for therapeutic interventions in the treatment of obesity and associated comorbidities.

Integrated multi-modal brain signatures predict sex-specific obesity status

Investigating sex as a biological variable is key to determine obesity manifestation and treatment response. Individual neuroimaging modalities have uncovered mechanisms related to obesity and altered ingestive behaviours. However, few, if any, studies have integrated data from multi-modal brain imaging to predict sex-specific brain signatures related to obesity. We used a data-driven approach to investigate how multi-modal MRI and clinical features predict a sex-specific signature of participants with high body mass index (overweight/obese) compared to non-obese body mass index in a sex-specific manner. A total of 78 high body mass index (55 female) and 105 non-obese body mass index (63 female) participants were enrolled in a cross-sectional study. All participants classified as high body mass index had a body mass index greater than 25 kg/m2 and non-obese body mass index had a body mass index between 19 and 20 kg/m2. Multi-modal neuroimaging (morphometry, functional resting-state MRI and diffusion-weighted scan), along with a battery of behavioural and clinical questionnaires were acquired, including measures of mood, early life adversity and altered ingestive behaviours. A Data Integration Analysis for Biomarker discovery using Latent Components was conducted to determine whether clinical features, brain morphometry, functional connectivity and anatomical connectivity could accurately differentiate participants stratified by obesity and sex. The derived models differentiated high body mass index against non-obese body mass index participants, and males with high body mass index against females with high body mass index obtaining balanced accuracies of 77 and 75%, respectively. Sex-specific differences within the cortico-basal-ganglia-thalamic-cortico loop, the choroid plexus-CSF system, salience, sensorimotor and default-mode networks were identified, and were associated with early life adversity, mental health quality and greater somatosensation. Results showed multi-modal brain signatures suggesting sex-specific cortical mechanisms underlying obesity, which fosters clinical implications for tailored obesity interventions based on sex.

All the Pringle ladies: Neural and behavioral responses to high-calorie food rewards in young adult women

Reward processing is vital for learning and survival, and can be indexed using the Reward Positivity (RewP), an event-related potential (ERP) component that is larger for rewards than losses. Prior work suggests that heightened motivation to obtain reward, as well as greater reward value, is associated with an enhanced RewP. However, the extent to which internal and external factors modulate neural responses to rewards, and whether such neural responses motivate reward-seeking behavior, remains unclear. The present study investigated whether the degree to which a reward is salient to an individual's current motivational state modulates the RewP, and whether the RewP predicts motivated behaviors, in a sample of 133 women. To elicit the RewP, participants completed a forced-choice food reward guessing task. Data were also collected on food-related behaviors (i.e., type of food chosen, consumption of the food reward) and motivational salience factors (i.e., self-reported hunger, time since last meal, and subjective "liking" of food reward). Results showed that hungrier participants displayed an enhanced RewP compared to less hungry individuals. Further, self-reported snack liking interacted with RewP magnitude to predict behavior, such that when participants reported low levels of snack liking, those with a smaller RewP were more likely to consume their snacks than those with a larger RewP. Our data suggest that food-related motivational state may increase neural sensitivity to food reward in young women, and that neural markers of reward sensitivity might interact with subjective reward liking to predict real-world eating behavior.

Sporadic fasting reduces attentional control without altering overall executive function in a binary classification task

Diets with intermittent fasting are an efficient method for producing clinically significant weight loss and preventing the development of obesity. However, individuals following intermittent fasting must face the difficulty of avoiding eating when experiencing the feeling of hunger. In this study, we investigated which aspects of executive function were affected following a prolonged period of food deprivation in participants that have never previously undergone intermittent fasting. Twenty-six participants with normal weight performed two binary classification tasks (Stop Signal (SST) and Go/NoGo) after either a 12 h fasting or a nonfasting period in separate sessions. We measured their performance in several underlying decision-making processes, such as response inhibition and attentional control. In line with previous studies, our results revealed that decision-making processes to resolve the classification task were unaffected by fasting. Response inhibition, as indexed by the stop signal reaction time in the SST, remained as well unaltered after food deprivation. Rather, we observed a higher error rate in NoGo trials following a fasting period, which was associated with disrupted attentional control. Overall, these results indicate that when a hunger feeling reaches consciousness, it induces deficits over certain aspects of attentional control. Our findings hint at the importance of structured behavioral change strategies to cope with fasting-induced difficulties in attentional control, to help achieve weight management goals through successful self-monitoring of food intake.

The Neural Processes in Food Decision-making and their Effect on Daily Diet Management in Successful and Unsuccessful Restrained Eaters

This study aimed to explore the neural mechanisms underlying food decision making in unsuccessful restrained eaters (US-REs) and successful restrained eaters (S-REs). During a functional magnetic resonance imaging scan, participants were required to choose between pairs of high- and low-calorie foods under the following conditions: the congruent condition (choose between high- and low-calorie foods with the same level of tastiness) and incongruent condition (choose between high-calorie foods tastier than the corresponding low-calorie foods). Subsequently, the participants' diets were monitored for one week. The behavioral results showed that US-REs (n = 28) chose more high-calorie foods than S-REs (n = 26); in contrast, S-REs spent more time in choosing for the incongruent than the congruent condition. The fMRI results found that US-REs exhibited more activity in reward regions (caudate and thalamus) than S-REs in the congruent condition. In the incongruent condition, S-REs showed stronger functional connectivity between the conflict-monitoring region (anterior cingulate cortex) and inhibitory-control regions (inferior frontal gyrus [IFG] and medial frontal gyrus) than US-REs. In both the conditions, increased activation of the insula, putamen, middle frontal gyrus, and IFG could predict increased food intake among US-REs in the following week. Furthermore, in both the conditions, increased IFG activation could predict decreased food cravings among S-REs during the following week. Our results suggest that US-REs have a strong reward response to food. Compared to US-REs, S-REs are more guided more by the goal of weight control, and exhibit strong functional connections between the conflict-monitoring and inhibitory-control regions. Therefore, eating enjoyment and weight-control goals influence restrained eating in daily life.

Transcranial direct current stimulation (tDCS) to dorsolateral prefrontal cortex influences perceived pleasantness of food

The ability to regulate the intake of unhealthy foods is critical in modern, calorie dense food environments. Frontal areas of the brain, such as the dorsolateral prefrontal cortex (DLPFC), are thought to play a central role in cognitive control and emotional regulation. Therefore, increasing activity in the DLPFC may enhance these functions which could improve the ability to reappraise and resist consuming highly palatable but unhealthy foods. One technique for modifying brain activity is transcranial direct current stimulation (tDCS), a non-invasive technique for modulating neuronal excitability that can influence performance on a range of cognitive tasks. We tested whether anodal tDCS targeting the right DLPFC would influence how people perceived highly palatable foods. In the present study, 98 participants were randomly assigned to receive a single session of active tDCS (2.0 mA) or sham stimulation. While receiving active or sham stimulation, participants viewed images of highly palatable foods and reported how pleasant it would be to eat each food (liking) and how strong their urge was to eat each food (wanting). We found that participants who received active versus sham tDCS stimulation perceived food as less pleasant, but there was no difference in how strong their urge was to eat the foods. Our findings suggest that modulating excitability in the DLPFC influences "liking" but not "wanting" of highly palatable foods. Non-invasive brain stimulation might be a useful technique for influencing the hedonic experience of eating but more work is needed to understand when and how it influences food cravings.

Differential neural reward reactivity in response to food advertising medium in children

Introduction

Food cues including food advertisements (ads) activate brain regions related to motivation and reward. These responses are known to correlate with eating behaviors and future weight gain. The objective of this study was to compare brain responses to food ads by different types of ad mediums, dynamic (video) and static (images), to better understand how medium type impacts food cue response.

Methods

Children aged 9-12 years old were recruited to complete a functional magnetic resonance imaging (fMRI) paradigm that included both food and non-food dynamic and static ads. Anatomical and functional images were preprocessed using the fMRIPrep pipeline. A whole-brain analysis and a targeted region-of-interest (ROI) analysis for reward regions (nucleus accumbens, orbitofrontal cortex, amygdala, insula, hypothalamus, ventral tegmental area, substantia nigra) were conducted. Individual neural responses to dynamic and static conditions were compared using a paired t-test. Linear mixed-effects models were then constructed to test the differential response by ad condition after controlling for age, sex, BMI-z, physical activity, and % of kcal consumed of a participant's estimated energy expenditure in the pre-load prior to the MRI scan.

Results

A total of 115 children (mean=10.9 years) completed the fMRI paradigm. From the ROI analyses, the right and left hemispheres of the amygdala and insula, and the right hemisphere of the ventral tegmental area and substantia nigra showed significantly higher responses for the dynamic food ad medium after controlling for covariates and a false discovery rate correction. From the whole-brain analysis, 21 clusters showed significant differential responses between food ad medium including the precuneus, middle temporal gyrus, superior temporal gyrus, and inferior frontal gyrus, and all regions remained significant after controlling for covariates.

Discussion

Advertising medium has unique effects on neural response to food cues. Further research is needed to understand how this differential activation by ad medium ultimately affects eating behaviors and weight outcomes.

Room for Feelings: A “Working Memory” Account of Affective Processing

In the past decades, affective science has overwhelmingly demonstrated the unique properties of affective information to bias our attention, memory, and decisions. At the same time, accumulating evidence suggests that neutral and affective representations rely on the same working memory substrates for the selection and computation of information and that they are therefore restricted by the same capacity limitations that these substrates impose. Here, we integrate these insights into a working memory model of affective processing (WMAP). Drawing on competitive access models of working memory, we discuss its role in the various stages of affective processing, from attentional selection to maintenance and memory storage, and resulting feelings and actions. We end our overview with some open questions and future directions.

Emotional Eating and Binge Eating Disorders and Night Eating Syndrome in Polycystic Ovary Syndrome-A Vicious Circle of Disease: A Systematic Review

Obesity is an established risk factor for the development of polycystic ovary syndrome (PCOS), especially phenotype A. PCOS is an important cause of fertility disorders in a large group of women of reproductive age. For many years, effective methods of treating hormonal disorders associated with PCOS have been sought in order to restore ovulation with regular menstrual cycles. Numerous studies support obesity treatment as an effective therapeutic method for many women. A seemingly simple method of treatment may prove to be particularly difficult in this group of women. The reason for this may be the lack of recognition the primary cause of obesity development or the occurrence of a vicious circle of disease. Primary causes of developing obesity may be emotional eating (EE) and eating disorders (EDs), such as binge eating disorder (BED) and its extreme form, addictive eating, as well as night eating syndrome (NES). All of these are caused by impaired function of the reward system. Consequently, these disorders can develop or be exacerbated in women with obesity and PCOS as a result of depression and anxiety related to hirsutism and fertility disturbances. Therefore, for the effective treatment of obesity, it is very important to recognize and treat EE, BED, and NES, including the appropriate selection of pharmacotherapy and psychotherapy. Therefore, the aim of our manuscript is to analyze the available data on the relationships between EE, BED, NES, obesity, and PCOS and their impact on the treatment of obesity in women with PCOS.

[11C]carfentanil PET imaging for studying the peripheral opioid system in vivo: effect of photoperiod on mu-opioid receptor availability in brown adipose tissue

PURPOSE

Photoperiod determines the metabolic activity of brown adipose tissue (BAT) and affects the food intake and body mass of mammals. Sympathetic innervation of the BAT controls thermogenesis and facilitates physiological adaption to seasonal changes, but the exact mechanism remains elusive. Previous studies have shown that central opioid signaling regulates BAT thermogenesis, and that the expression of the brain mu-opioid receptor (MOR) varies seasonally. Therefore, it is important to know whether MOR expression in BAT shows seasonal variation.

METHODS

We determined the effect of photoperiod on BAT MOR availability using [11C]carfentanil positron emission tomography (PET). Adult rats (n = 9) were repeatedly imaged under various photoperiods in order to simulate seasonal changes.

RESULTS

Long photoperiod was associated with low MOR expression in BAT (β =  - 0.04, 95% confidence interval: - 0.07, - 0.01), but not in muscles. We confirmed the expression of MOR in BAT and muscle using immunofluorescence staining.

CONCLUSION

Photoperiod affects MOR availability in BAT. Sympathetic innervation of BAT may influence thermogenesis via the peripheral MOR system. The present study supports the utility of [11C]carfentanil PET to study the peripheral MOR system.

Development of Chinese food picture library for inducing food cravings

Cue-induced food cravings are strong desires directed toward specific foods, usually ones with high caloric content, and can lead to overeating. However, although food cravings vary according to individual preferences for specific high-calorie food subtypes, a structured library of food craving-inducing pictures including multiple categories of high-calorie foods does not yet exist. Here, we developed and validated a picture library of Chinese foods (PLCF) consisting of five subtypes of high-calorie foods (i.e., sweets, starches, salty foods, fatty foods, and sugary drinks) to allow for more nuanced future investigations in food craving research, particularly in Chinese cultural contexts. We collected 100 food images representing these five subtypes, with four food items per subtype depicted in five high-resolution photographs each. We recruited 241 individuals with overweight or obesity to rate the food pictures based on craving, familiarity, valence, and arousal dimensions. Of these participants, 213 reported the severity of problematic eating behaviors as a clinical characteristic. Under the condition of mixing multiple subtypes of high-calorie foods, we did not observe significant differences in craving ratings for high- and low-calorie food images (p _tukey > 0.05). Then, we compared each subtype of high-calorie food images to low-calorie ones, and found craving ratings were greater for the images of salty foods and sugary drinks (ps < 0.05). Furthermore, we conducted a subgroup analysis of individuals according to whether they did or did not meet the criteria for food addiction (FA) and found that greater cravings induced by the images of high-calorie food subtypes (i.e., salty foods and sugary drinks) only appeared in the subgroup that met the FA criteria. The results show that the PLCF is practical for investigating food cravings.

Multi-omics gut microbiome signatures in obese women: role of diet and uncontrolled eating behavior

BACKGROUND

Obesity and related co-morbidities represent a major health challenge nowadays, with a rapidly increasing incidence worldwide. The gut microbiome has recently emerged as a key modifier of human health that can affect the development and progression of obesity, largely due to its involvement in the regulation of food intake and metabolism. However, there are still few studies that have in-depth explored the functionality of the human gut microbiome in obesity and even fewer that have examined its relationship to eating behaviors.

METHODS

In an attempt to advance our knowledge of the gut-microbiome-brain axis in the obese phenotype, we thoroughly characterized the gut microbiome signatures of obesity in a well-phenotyped Italian female cohort from the NeuroFAST and MyNewGut EU FP7 projects. Fecal samples were collected from 63 overweight/obese and 37 normal-weight women and analyzed via a multi-omics approach combining 16S rRNA amplicon sequencing, metagenomics, metatranscriptomics, and lipidomics. Associations with anthropometric, clinical, biochemical, and nutritional data were then sought, with particular attention to cognitive and behavioral domains of eating.

RESULTS

We identified four compositional clusters of the gut microbiome in our cohort that, although not distinctly associated with weight status, correlated differently with eating habits and behaviors. These clusters also differed in functional features, i.e., transcriptional activity and fecal metabolites. In particular, obese women with uncontrolled eating behavior were mostly characterized by low-diversity microbial steady states, with few and poorly interconnected species (e.g., Ruminococcus torques and Bifidobacterium spp.), which exhibited low transcriptional activity, especially of genes involved in secondary bile acid biosynthesis and neuroendocrine signaling (i.e., production of neurotransmitters, indoles and ligands for cannabinoid receptors). Consistently, high amounts of primary bile acids as well as sterols were found in their feces.

CONCLUSIONS

By finding peculiar gut microbiome profiles associated with eating patterns, we laid the foundation for elucidating gut-brain axis communication in the obese phenotype. Subject to confirmation of the hypotheses herein generated, our work could help guide the design of microbiome-based precision interventions, aimed at rewiring microbial networks to support a healthy diet-microbiome-gut-brain axis, thus counteracting obesity and related complications.