Correlation between Ventromedial Prefrontal Cortex Activation to Food Aromas and Cue-driven Eating: An fMRI Study

The neural substrates responsible for food odor processing: an activation likelihood estimation meta-analysis

In many species including humans, food odors appear to play a distinct role when compared with other odors. Despite their functional distinction, the neural substrates responsible for food odor processing remain unclear in humans. This study aimed to identify brain regions involved in food odor processing using activation likelihood estimation (ALE) meta-analysis. We selected olfactory neuroimaging studies conducted with sufficient methodological validity using pleasant odors. We then divided the studies into food and non-food odor conditions. Finally, we performed an ALE meta-analysis for each category and compared the ALE maps of the two categories to identify the neural substrates responsible for food odor processing after minimizing the confounding factor of odor pleasantness. The resultant ALE maps revealed that early olfactory areas are more extensively activated by food than non-food odors. Subsequent contrast analysis identified a cluster in the left putamen as the most likely neural substrate underlying food odor processing. In conclusion, food odor processing is characterized by the functional network involved in olfactory sensorimotor transformation for approaching behaviors to edible odors, such as active sniffing.

Gut-brain mechanisms underlying changes in disordered eating behaviour after bariatric surgery: a review

Bariatric surgery results in long-term weight loss and an improved metabolic phenotype due to changes in the gut-brain axis regulating appetite and glycaemia. Neuroendocrine alterations associated with bariatric surgery may also influence hedonic aspects of eating by inducing changes in taste preferences and central reward reactivity towards palatable food. However, the impact of bariatric surgery on disordered eating behaviours (e.g.: binge eating, loss-of-control eating, emotional eating and 'addictive eating'), which are commonly present in people with obesity are not well understood. Increasing evidence suggests gut-derived signals, such as appetitive hormones, bile acid profiles, microbiota concentrations and associated neuromodulatory metabolites, can influence pathways in the brain implicated in food intake, including brain areas involved in sensorimotor, reward-motivational, emotional-arousal and executive control components of food intake. As disordered eating prevalence is a key mediator of weight-loss success and patient well-being after bariatric surgery, understanding how changes in the gut-brain axis contribute to disordered eating incidence and severity after bariatric surgery is crucial to better improve treatment outcomes in people with obesity.

Localizing the human brain response to olfactory stimulation: A meta-analytic approach

The human sense of smell and the ability to detect and distinguish odors allows for the extraction of valuable information from the environment, thereby driving human behavior. Not only can the sense of smell help to monitor the safety of inhaled air, but it can also help to evaluate the edibility of food. Therefore, in an effort to further our understanding of the human sense of smell, the aim of this meta-analysis was to provide the scientific community with activation probability maps of the functional anatomy of the olfactory system, in addition to separate activation maps for specific odor categories (pleasant, food, and aversive odors). The activation likelihood estimation (ALE) method was utilized to quantify all relevant and available data to perform a formal statistical analysis on the inter-study concordance of various odor categories. A total of 81 studies (108 contrasts, 1053 foci) fulfilled our inclusion criteria. Significant ALE peaks were observed in all odor categories in brain areas typically associated with the functional neuroanatomy of olfaction including the piriform cortex, amygdala, insula, and orbitofrontal cortex, amongst others. Additional contrast analyses indicate clear differences in neural activation patterns between odor categories.

Food olfactory cues reactivity in individuals with obesity and the contribution of alexithymia

Obesity has been associated with increased reward sensitivity to food stimuli, but a few studies have addressed this issue by using odors. This study investigated whether obesity is associated with increased liking and wanting of food odors and whether alexithymia, a psychological construct characterized by diminished affective abilities, contributes to altered responsiveness to food. Liking and wanting for food and pleasant non-food odors were measured through explicit (self-report ratings) and implicit measures (heart rate and skin conductance) in 23 women with healthy weight (HW) and 20 women with overweight/obesity (OW/OB). Differently from the HW group, the OW/OB group explicitly liked food odors less than non-food odors; but, at the implicit level, there were no differences in heart rate response for both types of odors, indicating that they were equally liked. Moreover, at variance with the HW group, the OW/OB group did not exhibit increased skin conductance response for food compared to nonfood odors. Alexithymia was associated with increased implicit liking and explicit wanting of food odors, in particular in the HW group. These findings show that obesity is characterized by high levels of implicit food liking and low levels of implicit food wanting. Moreover, both affective and motivational responses to food reward seem to be affected by alexithymia, which should be taken into account by studies evaluating the effect of cue exposure intervention for obesity treatment.

Brain response to food odors is not associated with body mass index and obesity-related metabolic health measures

Smell perception plays a role in eating behavior and might be involved in the development of obesity. In fact, olfactory function is impaired in obesity and might depend on metabolic health factors. To date, the underlying neural mechanisms remain unclear. Here, we investigate neural processing of food-related odors in normal-weight, overweight and obese individuals. Fifty-three young and healthy participants (28.8 ± 4.4 years, 27 female; 24 normal-weight, 10 overweight, and 19 obese) were presented with high- (chocolate, potato chips) and low-caloric (orange, cucumber) food odors during a functional magnetic resonance imaging (fMRI). We also assessed olfactory identification ability, body mass index (BMI), body fat percentage, insulin resistance, and leptin levels. In brief, olfactory perception of food odors was linked to brain activity in the entorhinal and piriform cortex, and the insula, hippocampus, and amygdala. Insulin resistance was negatively related to olfactory identification. Additionally, perception of sweet versus savory odors was related to a higher brain activity in the right middle/superior frontal gyrus. Finally, we found no effect of obesity status, BMI, metabolic factors, or body fat percentage on neural responses to food odors. Overall, this suggests that food odor processing might depend on factors other than body weight status or associated markers of metabolic health.

Increased Brain Reward Responsivity to Food-Related Odors in Obesity

OBJECTIVE

Food odors serve as powerful stimuli signaling the food quality and energy density and direct food-specific appetite and consumption. This study explored obesity-related brain activation in response to odors related to high- or low-energy-dense foods.

METHODS

Seventeen participants with obesity (BMI > 30 kg/m² ; 4 males and 13 females) and twenty-one with normal weight (BMI < 25 kg/m² ; 9 males and 12 females) underwent a functional magnetic resonance imaging scan in which they received chocolate (high-energy-dense food) and cucumber (low-energy-dense food) odor stimuli. Participants' olfactory and gustatory functions were assessed by the "Sniffin' Sticks" and "Taste Strips" tests, respectively.

RESULTS

Compared with normal-weight controls, participants with obesity had lower odor sensitivity (phenylethyl alcohol) and decreased odor discrimination ability. However, participants with obesity demonstrated greater brain activation in response to chocolate compared with cucumber odors in the bilateral inferior frontal operculum and cerebellar vermis, right ventral anterior insula extending to putamen, right middle temporal gyrus, and right supramarginal areas.

CONCLUSIONS

The present study provides preliminary evidence that obesity is associated with heightened brain activation of the reward and flavor processing areas in response to chocolate versus cucumber odors, possibly because of the higher energy density and reinforcing value of chocolate compared with cucumber.

Dietary Restraint Related to Body Weight Maintenance and Neural Processing in Value-Coding Areas in Adolescents

BACKGROUND

There is an alarming increase in the obesity prevalence among children in an environment of increasing availability of preprocessed high-calorie foods. However, some people maintain a healthy weight even in such obesogenic environments. This difference in body weight management could be attributed to individual differences in dietary restraint; however, its underlying neurocognitive mechanisms in adolescents remain unclear.

OBJECTIVES

This study aimed to elucidate these neurocognitive mechanisms in adolescents by examining the relationships between dietary restraint and the food-related value-coding region located in the ventromedial prefrontal cortex (vmPFC).

METHODS

The association between dietary restraint and BMI was tested using a multilinear regression analysis in a large early adolescent cohort (n = 2554; age, 12.2 ± 0.3 years; BMI, 17.9 ± 2.5 kg/m2; 1354 boys). Further, an fMRI experiment was designed to assess the association between the vmPFC response to food images and dietary restraint in 30 adolescents (age, 17.6 ± 1.9 years; BMI, 20.7 ± 2.2 kg/m2; 13 boys). Additionally, using 54 individuals from the cohort (age, 14.5 ± 0.6 years; BMI, 18.8 ± 2.6 kg/m2; 31 boys), we assessed the association between dietary restraint and intrinsic vmPFC-related functional connectivity.

RESULTS

In the cohort, adolescents with increased dietary restraint showed a lower BMI (β = -0.38; P < 0.001; B = -0.06; SE = 0.003). The fMRI results showed a decreased vmPFC response to high-calorie food were correlated with greater dietary restraint. Moreover, there was an association of attenuated intrinsic vmPFC-related functional connectivity in the superior and middle frontal gyrus and the middle temporal gyrus with greater dietary restraint.

CONCLUSIONS

Our findings suggest that dietary restraint in adolescents could be a preventive factor for weight gain; its effect involves modulating the vmPFC, which is associated with food value coding.

Sensory cue reactivity: Sensitization in alcohol use disorder and obesity

Neuroimaging techniques to measure the function of the human brain such as electroencephalography (EEG), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI), are powerful tools for understanding the underlying neural circuitry associated with alcohol use disorder (AUD) and obesity. The sensory (visual, taste and smell) paradigms used in neuroimaging studies represent an ideal platform to investigate the connection between the different neural circuits subserving the reward/executive control systems in these disorders, which may offer a translational mechanism for novel intervention predictions. Thus, the current review provides an integrated summary of the recent neuroimaging studies that have applied cue-reactivity paradigms and neuromodulation strategies to explore underlying alterations in neural circuitry as well in treatment strategies in AUD and obesity. Finally, we discuss literature on mechanisms associated with increased alcohol sensitivity post-bariatric surgery (BS) which offers guidance for future research to use sensory percepts in elucidating the relation of reward signaling in AUD development post-BS.

COVID 19-Induced Smell and Taste Impairments: Putative Impact on Physiology

Smell and taste impairments are recognized as common symptoms in COVID 19 patients even in an asymptomatic phase. Indeed, depending on the country, in up to 85-90% of cases anosmia and dysgeusia are reported. We will review briefly the main mechanisms involved in the physiology of olfaction and taste focusing on receptors and transduction as well as the main neuroanatomical pathways. Then we will examine the current evidences, even if still fragmented and unsystematic, explaining the disturbances and mode of action of the virus at the level of the nasal and oral cavities. We will focus on its impact on the peripheral and central nervous system. Finally, considering the role of smell and taste in numerous physiological functions, especially in ingestive behavior, we will discuss the consequences on the physiology of the patients as well as management regarding food intake.

Brain Responses to Food Odors Associated With BMI Change at 2-Year Follow-Up

The understanding of food cue associated neural activations that predict future weight variability may guide the design of effective prevention programs and treatments for overeating and obesity. The current study investigated the association between brain response to different food odors with varied energy density and individual changes of body mass index (BMI) over 2 years. Twenty-five participants received high-fat (chocolate and peanut), low-fat (bread and peach) food odors, and a nonfood odor (rose) while the brain activation was measured using functional magnetic resonance imaging (fMRI). BMIs were calculated with participant’s self-reported body weight and height collected at the time of the fMRI scan and again at 2 years later. Regression analyses revealed significant negative correlations between BMI increase over 2 years and brain activation of the bilateral precuneus and the right posterior cingulate cortex (PCC) in response to high-fat vs. low-fat food odors. Also, brain activation of the right supplementary motor area (SMA) in response to food vs. non-food odor was negatively correlated to subsequent BMI increase over 2 years. Taken together, the current findings suggest that individual differences in neural responsivity to (high calorie) food odors in brain regions of the default mode and motor control network serve as a neural marker for future BMI change.

No evidence for an association between obesity and milkshake liking

BACKGROUND

Prevailing models of obesity posit that hedonic signals override homeostatic mechanisms to promote overeating in today's food environment. What researchers mean by "hedonic" varies considerably, but most frequently refers to an aggregate of appetitive events including incentive salience, motivation, reinforcement, and perceived pleasantness. Here we define hedonic as orosensory pleasure experienced during eating and set out to test whether there is a relationship between adiposity and the perceived pleasure of a palatable and energy-dense milkshake.

METHODS

The perceived liking, wanting, and intensity of two palatable and energy-dense milkshakes were assessed using the Labeled Hedonic Scale (1), visual analog scale (VAS), and Generalized Labeled Magnitude Scale (2) in 110 individuals ranging in body mass index (BMI) from 19.3 to 52.1 kg/m². Waist circumference, waist-hip ratio, and percent body fat were also measured. Importantly, unlike the majority of prior studies, we attempted to standardize internal state by instructing participants to arrive to the laboratory neither hungry nor full and at least 1-h fasted. Data were analyzed with general linear and linear mixed effects models (GLMs). Hunger ratings were also examined prior to hedonic measurement and included as covariates in our analyses.

RESULTS

We identified a significant association between ratings of hunger and milkshake liking and wanting. By contrast, we found no evidence for a relationship between any measure of adiposity and ratings of milkshake liking, wanting, or intensity.

CONCLUSIONS

We conclude that adiposity is not associated with the pleasure experienced during consumption of our energy-dense and palatable milkshakes. Our results provide further evidence against the hypothesis that heightened hedonic signals drive weight gain.

Rethinking Food Reward

The conscious perception of the hedonic sensory properties of caloric foods is commonly believed to guide our dietary choices. Current and traditional models implicate the consciously perceived hedonic qualities of food as driving overeating, whereas subliminal signals arising from the gut would curb our uncontrolled desire for calories. Here we review recent animal and human studies that support a markedly different model for food reward. These findings reveal in particular the existence of subcortical body-to-brain neural pathways linking gastrointestinal nutrient sensors to the brain's reward regions. Unexpectedly, consciously perceptible hedonic qualities appear to play a less relevant, and mostly transient, role in food reinforcement. In this model, gut-brain reward pathways bypass cranial taste and aroma sensory receptors and the cortical networks that give rise to flavor perception. They instead reinforce behaviors independently of the cognitive processes that support overt insights into the nature of our dietary decisions.

Brain Imaging of Taste Perception in Obesity: a Review

PURPOSE OF REVIEW

We summarize neuroimaging findings related to processing of taste (fat, salt, umami, bitter, and sour) in the brain and how they influence hedonic responses and eating behaviors and their role in obesity.

RECENT FINDINGS

Neuroimaging studies in obese individuals have revealed alterations in reward/motivation, executive control/self-regulation, and limbic/affective circuits that are implicated in food and drug addiction. Psychophysical studies show that sensory properties of food ingredients may be associated with anthropometric and neurocognitive outcomes in obesity. However, few studies have examined the neural correlates of taste and processing of calories and nutrient content in obesity. The literature of neural correlated of bitter, sour, and salty tastes remains sparse in obesity. Most published studies have focused on sweet, followed by fat and umami taste. Studies on calorie processing and its conditioning by preceding taste sensations have started to delineate a dynamic pattern of brain activation associated with appetition. Our expanded understanding of taste processing in the brain from neuroimaging studies is poised to reveal novel prevention and treatment targets to help address overeating and obesity.

The effect of hunger and satiety in the judgment of ethical violations

Human history is studded with instances where instinctive motivations take precedence over ethical choices. Nevertheless, the evidence of any linking between motivational states and morality has never been systematically explored. Here we addressed this topic by testing a possible linking between appetite and moral judgment. We compared moral disapproval ratings (MDR) for stories of ethical violations in participants under fasting and after having eaten a snack. Our results show that subjective hunger, measured via self-reported rating, reduces MDR for ethical violations. Moreover, the higher the disgust sensitivity the higher the MDR for ethical violations. This study adds new insights to research on physiological processes influencing morality by showing that appetite affects moral disapproval of ethical violations.

Food-Related Odors Activate Dopaminergic Brain Areas

Food-associated cues of different sensory categories have often been shown to be a potent elicitor of cerebral activity in brain reward circuits. Smells influence and modify the hedonic qualities of eating experience, and in contrast to smells not associated with food, perception of food-associated odors may activate dopaminergic brain areas. In this study, we aimed to verify previous findings related to the rewarding value of food-associated odors by means of an fMRI design involving carefully preselected odors of edible and non-edible substances. We compared activations generated by three food and three non-food odorants matching in terms of intensity, pleasantness and trigeminal qualities. We observed that for our mixed sample of 30 hungry and satiated participants, food odors generated significantly higher activation in the anterior cingulate cortex (right and left), insula (right), and putamen (right) than non-food odors. Among hungry subjects, regardless of the odor type, we found significant activation in the ventral tegmental area in response to olfactory stimulation. As our stimuli were matched in terms of various perceptual qualities, this result suggests that edibility of an odor source indeed generates specific activation in dopaminergic brain areas.

Emotional eating and routine restraint scores are associated with activity in brain regions involved in urge and self-control

Researchers have proposed a variety of behavioral traits that may lead to weight gain and obesity; however, little is known about the neurocognitive mechanisms underlying these weight-related eating behaviors. In this study, we measured activation of reward circuitry during a task requiring response and inhibition to food stimuli. We assessed participants' emotional eating, external eating, and two subscales of dietary restraint-routine restraint and compensatory restraint-using the Weight-Related Eating Questionnaire. For routine restraint, we found positive associations with activation in the insula, dorsolateral prefrontal cortex, anterior cingulate cortex, orbitofrontal cortex and ventromedial prefrontal cortex in response to high-calorie versus low-calorie foods. For emotional eating, we found positive associations with insula and dorsolateral prefrontal cortex activation in response to high-calorie versus low-calorie foods. We also found positive associations between emotional eating and dorsolateral prefrontal cortex activation in response to approach versus inhibition towards high-calorie foods. Thus, our results demonstrate an increase in activation across brain regions related to self-control and urges in response to high-calorie food associated with both emotional eating and routine restraint. Overall, these results support the construct validity of both emotional eating and routine restraint and provide preliminary evidence that these subscales have similar neural correlates.

A core eating network and its modulations underlie diverse eating phenomena

We propose that a core eating network and its modulations account for much of what is currently known about the neural activity underlying a wide range of eating phenomena in humans (excluding homeostasis and related phenomena). The core eating network is closely adapted from a network that Kaye, Fudge, and Paulus (2009) proposed to explain the neurocircuitry of eating, including a ventral reward pathway and a dorsal control pathway. In a review across multiple literatures that focuses on experiments using functional Magnetic Resonance Imaging (fMRI), we first show that neural responses to food cues, such as food pictures, utilize the same core eating network as eating. Consistent with the theoretical perspective of grounded cognition, food cues activate eating simulations that produce reward predictions about a perceived food and potentially motivate its consumption. Reviewing additional literatures, we then illustrate how various factors modulate the core eating network, increasing and/or decreasing activity in subsets of its neural areas. These modulating factors include food significance (palatability, hunger), body mass index (BMI, overweight/obesity), eating disorders (anorexia nervosa, bulimia nervosa, binge eating), and various eating goals (losing weight, hedonic pleasure, healthy living). By viewing all these phenomena as modulating a core eating network, it becomes possible to understand how they are related to one another within this common theoretical framework. Finally, we discuss future directions for better establishing the core eating network, its modulations, and their implications for behavior.

Listening to music in a risk-reward context: The roles of the temporoparietal junction and the orbitofrontal/insular cortices in reward-anticipation, reward-gain, and reward-loss

Artificial rewards, such as visual arts and music, produce pleasurable feelings. Popular songs in the verse-chorus form provide a useful model for understanding the neural mechanisms underlying the processing of artificial rewards, because the chorus is usually the most rewarding element of a song. In this functional magnetic resonance imaging (fMRI) study, the stimuli were excerpts of 10 popular songs with a tensioned verse-to-chorus transition. We examined the neural correlates of three phases of reward processing: (1) reward-anticipation during the verse-to-chorus transition, (2) reward-gain during the first phrase of the chorus, and (3) reward-loss during the unexpected noise followed by the verse-to-chorus transition. Participants listened to these excerpts in a risk-reward context because the verse was followed by either the chorus or noise with equal probability. The results showed that reward-gain and reward-loss were associated with left- and right-biased temporoparietal junction activation, respectively. The bilateral temporoparietal junctions were active during reward-anticipation. Moreover, we observed left-biased lateral orbitofrontal activation during reward-anticipation, whereas the medial orbitofrontal cortex was activated during reward-gain. The findings are discussed in relation to the cognitive and emotional aspects of reward processing.

The apéritif effect: Alcohol's effects on the brain's response to food aromas in women

OBJECTIVE

Consuming alcohol prior to a meal (an apéritif) increases food consumption. This greater food consumption may result from increased activity in brain regions that mediate reward and regulate feeding behavior. Using functional magnetic resonance imaging, we evaluated the blood oxygenation level dependent (BOLD) response to the food aromas of either roast beef or Italian meat sauce following pharmacokinetically controlled intravenous infusion of alcohol.

METHODS

BOLD activation to food aromas in non-obese women (n = 35) was evaluated once during intravenous infusion of 6% v/v EtOH, clamped at a steady-state breath alcohol concentration of 50 mg%, and once during infusion of saline using matching pump rates. Ad libitum intake of roast beef with noodles or Italian meat sauce with pasta following imaging was recorded.

RESULTS

BOLD activation to food relative to non-food odors in the hypothalamic area was increased during alcohol pre-load when compared to saline. Food consumption was significantly greater, and levels of ghrelin were reduced, following alcohol.

CONCLUSIONS

An alcohol pre-load increased food consumption and potentiated differences between food and non-food BOLD responses in the region of the hypothalamus. The hypothalamus may mediate the interplay of alcohol and responses to food cues, thus playing a role in the apéritif phenomenon.

Neural responses to visual food cues according to weight status: a systematic review of functional magnetic resonance imaging studies

Emerging evidence from recent neuroimaging studies suggests that specific food-related behaviors contribute to the development of obesity. The aim of this review was to report the neural responses to visual food cues, as assessed by functional magnetic resonance imaging (fMRI), in humans of differing weight status. Published studies to 2014 were retrieved and included if they used visual food cues, studied humans >18 years old, reported weight status, and included fMRI outcomes. Sixty studies were identified that investigated the neural responses of healthy weight participants (n = 26), healthy weight compared to obese participants (n = 17), and weight-loss interventions (n = 12). High-calorie food images were used in the majority of studies (n = 36), however, image selection justification was only provided in 19 studies. Obese individuals had increased activation of reward-related brain areas including the insula and orbitofrontal cortex in response to visual food cues compared to healthy weight individuals, and this was particularly evident in response to energy dense cues. Additionally, obese individuals were more responsive to food images when satiated. Meta-analysis of changes in neural activation post-weight loss revealed small areas of convergence across studies in brain areas related to emotion, memory, and learning, including the cingulate gyrus, lentiform nucleus, and precuneus. Differential activation patterns to visual food cues were observed between obese, healthy weight, and weight-loss populations. Future studies require standardization of nutrition variables and fMRI outcomes to enable more direct comparisons between studies.

Ventral frontal satiation-mediated responses to food aromas in obese and normal-weight women

BACKGROUND

Sensory properties of foods promote and guide consumption in hunger states, whereas satiation should dampen the sensory activation of ingestive behaviors. Such activation may be disordered in obese individuals.

OBJECTIVE

Using functional magnetic resonance imaging (fMRI), we studied regional brain responses to food odor stimulation in the sated state in obese and normal-weight individuals targeting ventral frontal regions known to be involved in coding for stimulus reward value.

DESIGN

Forty-eight women (25 normal weight; 23 obese) participated in a 2-day (fed compared with fasting) fMRI study while smelling odors of 2 foods and an inedible, nonfood object. Analyses were conducted to permit an examination of both general and sensory-specific satiation (satiation effects specific to a given food).

RESULTS

Normal-weight subjects showed significant blood oxygen level-dependent responses in the ventromedial prefrontal cortex (vmPFC) to food aromas compared with responses induced by the odor of an inedible object. Normal-weight subjects also showed general (but not sensory-specific) satiation effects in both the vmPFC and orbitofrontal cortex. Obese subjects showed no differential response to the aromas of food and the inedible object when fasting. Within- and between-group differences in satiation were driven largely by changes in the response to the odor of the inedible stimulus. Responses to food aromas in the obese correlated with trait negative urgency, the tendency toward negative affect-provoked impulsivity.

CONCLUSIONS

Ventral frontal signaling of reward value may be disordered in obesity, with negative urgency heightening responses to food aromas. The observed nature of responses to food and nonfood stimuli suggests that future research should independently quantify each to fully understand brain reward signaling in obesity.

Dietary disinhibition modulates neural valuation of food in the fed and fasted states

BACKGROUND

Dietary disinhibition is a behavioral trait associated with weight gain and obesity. Because food choices are made according to the relative value assigned to each option, examination of valuation signals through functional magnetic resonance imaging (fMRI) may elucidate the neural basis for the association between dietary disinhibition and weight gain.

OBJECTIVE

We examined how food valuation signals differ in the fed and fasted states between persons with high dietary disinhibition (HD) and low dietary disinhibition (LD).

DESIGN

Sixteen men with HD and 14 with LD underwent fMRI once while fasted and once after being fed in a counterbalanced order. In-scanner preference to consume a test food relative to a neutral-tasting, neutral-health reference food was examined. The slope of magnetic resonance signal change corresponding to these food preferences constituted the food valuation signal that was compared across disinhibition group and satiety state.

RESULTS

Both the HD and LD participants reported being less hungry (F(1,28) = 113.11, P < 0.001) after being fed than when fasted. However, food valuation signals in the ventromedial prefrontal cortex (vmPFC) differed between the groups (F(1,28) = 21.34, P < 0.001). Although LD participants showed attenuated vmPFC activity after being fed (t(13) = 4.11, P < 0.001), HD participants showed greater vmPFC activity in the fed than in the fasted state (t(15) = -2.56, P < 0.05).

CONCLUSIONS

Despite reporting normal decreases in hunger ratings after being fed, persons with HD have an altered neural valuation of food. This may be a mechanism underlying their propensity to overeat and gain weight. This trial was registered at clinicaltrials.gov as NCT00988819.