Prefrontal cortex, obesity, appetite

Larger portions of food elicit greater intake than smaller portions of food, particularly when foods are high in energy density (kcal/g; ED). The neural mechanisms underlying this effect remain unclear. The present study used fMRI to assess brain activation to food (higher-ED, lower-ED) and non-food (office supplies) images presented in larger and smaller (i.e., age-appropriate) amounts in 61, 7-8-year-olds (29 male, 32 female) without obesity. Larger amounts of food increased activation in bilateral visual and right parahippocampal areas compared to smaller amounts; greater activation to food amount (larger > smaller) in this cluster was associated with smaller increases in food intake as portions increased...

Changes in eating behaviour including reductions in appetite and food intake, and healthier food cue reactivity, reward, hedonics and potentially also preference, contribute to weight loss and its health benefits after obesity surgery. Functional magnetic resonance imaging (fMRI) has been increasingly used to interrogate the neural correlates of eating behaviour in obesity, including brain reward-cognitive systems, changes after obesity surgery, and links with alterations in the gut-hormone-brain axis. Neural responses to food cues can be measured by changes in blood oxygen level dependent (BOLD) signal in brain regions involved in reward processing, including caudate, putamen, nucleus accumbens, insula, amygdala, orbitofrontal cortex, and top-down inhibitory control, including dorsolateral prefrontal cortex (dlPFC)...

Computational models and neurophysiological data propose that a 'gating mechanism' coordinates distractor-resistant maintenance and flexible updating of working memory contents: While maintenance of information is mainly implemented in the prefrontal cortex, updating of information is signaled by phasic increases in dopamine in the striatum. Previous literature demonstrates structural and functional alterations in these brain areas, as well as differential dopamine transmission among individuals with obesity, suggesting potential impairments in these processes...

Growing evidence supports the effectiveness of cognitive reappraisal in down-regulating food desire. Still, the neural bases of food craving down-regulation via reappraisal, as well as their degree of overlap versus specificity compared with emotion down-regulation, remain unclear. We addressed this gap through activation likelihood estimation (ALE) meta-analyses of neuroimaging studies on the neural bases of (a) food craving down-regulation, and (b) emotion down-regulation, alongside conjunction and subtraction analyses among the resulting maps...

BACKGROUND: Metabolic and bariatric surgery (MBS) is the most effective and durable obesity treatment. However, there is heterogeneity in weight outcomes, which is partially attributed to variability in appetite and eating regulation. Patients with a strong desire to eat in response to the reward of palatable foods are more likely to overeat and experience suboptimal outcomes. This subgroup, classified as at risk, may benefit from repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation technique that shows promise for reducing cravings and consumption of addictive drugs and food; no study has evaluated how rTMS affects the reinforcing value of food and brain reward processing in the context of MBS...

Various roles of intestinal flora in the gut-brain axis response pathway have received enormous attention because of their unique position in intestinal flora-derived metabolites regulating hormones, inducing appetite, and modulating energy metabolism. Reward pathways in the brain play a crucial role in gut-brain communications, but the mechanisms have not been methodically understood. This review outlined the mechanisms by which leptin, ghrelin, and insulin are influenced by intestinal flora-derived metabolites to regulate appetite and body weight, focused on the significance of the paraventricular nucleus and ventromedial prefrontal cortex in food reward...

Consistent with the idea that deficits in inhibition limit resistance to tempting, tasty, high-calorie foods, and might result in a higher BMI, we test whether people with higher BMIs (BMI >25 kg/m2 ) present inefficient inhibitory control over food-related responses. To unpack this association, we also examine individual differences in the neural mechanisms of food inhibitory control in healthy vs higher BMI individuals. We test these aspects with a sample of 109 participants (49 with higher BMI and 60 with healthy BMI) and the food stop-signal task, which was used to examine individuals' inhibitory control...

BACKGROUND: Melanocortin 4 receptor (MC4R) activity in the hypothalamus is crucial for regulation of metabolism and food intake. The peptide ligands for the MC4R are associated with feeding, energy expenditure, and also with complex behaviors that orchestrate energy intake and expenditure, but the downstream neuroanatomical and neurochemical targets associated with these behaviors are elusive. In addition to strong expression in the hypothalamus, the MC4R is highly expressed in the medial prefrontal cortex, a region involved in executive function and decision-making...

Inhibitory associative learning counters the effects of excitatory learning, whether appetitively or aversively motivated. Moreover, the affective responses accompanying the inhibitory associations are of opponent valence to the excitatory conditioned responses. Inhibitors for negative aversive outcomes (e.g. shock) signal safety, while inhibitors for appetitive outcomes (e.g. food reward) elicit frustration and/or disappointment. This raises the question as to whether studies using appetitive and aversive conditioning procedures should demonstrate the same neural substrates for inhibitory learning...

INTRODUCTION: In the modern obesogenic environment, heightened reactivity to food-associated cues plays a major role in overconsumption by evoking appetitive responses. Accordingly, functional magnetic resonance imaging (fMRI) studies have implicated regions of the salience and rewards processing in this dysfunctional food cue-reactivity, but the temporal dynamics of brain activation (sensitization or habituation over time) remain poorly understood. METHODS: Forty-nine obese or overweight adults were scanned in a single fMRI session to examine brain activation during the performance of a food cue-reactivity task...

BACKGROUND: A greater understanding of how the brain controls appetite is fundamental to developing new approaches for treating diseases characterized by dysfunctional feeding behavior, such as obesity and anorexia nervosa. METHODS: By modeling neural network dynamics related to homeostatic state and body mass index, we identified a novel pathway projecting from the medial prefrontal cortex (mPFC) to the lateral hypothalamus (LH) in humans (n = 53). We then assessed the physiological role and dissected the function of this mPFC-LH circuit in mice...

Palatable foods can stimulate appetite without hunger, and unconstrained overeating underlies obesity and binge eating disorder. Women are more prone to obesity and binge eating than men but the neural causes of individual differences are unknown. In an animal model of hedonic eating, a prior study found that females were more susceptible than males to eat palatable food when sated and that the neuropeptide orexin/hypocretin (ORX) was crucial in both sexes. The current study examined potential extra-hypothalamic forebrain targets of ORX signaling during hedonic eating...

CONTEXT: The neural regulation of appetite and energy homeostasis significantly overlaps with the neurobiology of stress. Frequent exposure to repeated acute stressors may cause increased allostatic load and subsequent dysregulation of the cortico-limbic striatal system leading to inefficient integration of postprandial homeostatic and hedonic signals. It is therefore important to understand the neural mechanisms by which stress generates alterations in appetite that may drive weight gain...

BACKGROUND: Complex interactions between the brain, gut and adipose tissue allow to recognize obesity as a neurometabolic disorder. The recent data have shown that gut microbiota can play a potential role in obesity development. Transcranial direct current stimulation (tDCS) is a safe and non-invasive technique to modulate the activity of cerebral cortex and other connected brain areas also in context of appetite control. The objective of this study was to evaluate the effects of repetitive anodal tDCS (AtDCS) of prefrontal cortex on feeding behavior, metabolic status and selected phyla of gut microbiota in rats with obesity induced by high-calorie diet (HCD)...

Aberrant responses within homeostatic, hedonic and cognitive systems contribute to poor appetite control in those with an overweight phenotype. The hedonic system incorporates limbic and meso-limbic regions involved in learning and reward processing, as well as cortical regions involved in motivation, decision making and gustatory processing. Equally important within this complex, multifaceted framework are the cognitive systems involved in inhibitory control and valuation of food choices. Regions within these systems display insulin receptors and pharmacologically increasing central insulin concentrations using intranasal administration (IN-INS) has been shown to significantly reduce appealing food cue responsiveness and also food intake...

Overweight and obesity have become international public health problems, so there is an urgent need to implement effective interventions that prevent these concerning health issues. Designing personalized (tailored) dietary communications has become one of the most effective tools in reducing unhealthy eating behavior, when compared with one-size-fits-all messages (untailored). However, more research is required to gain a complete understanding of the underlying mechanisms by which tailored nutritional messages elicit reductions in unhealthy dietary behavior...

Food cue exposure can trigger eating. Food cue reactivity (FCR) is a conditioned response to food cues and includes physiological responses and activation of reward-related brain areas. FCR can be affected by hunger and weight status. The appetite-regulating hormones ghrelin and leptin play a pivotal role in homeostatic as well as hedonic eating. We examined the association between ghrelin and leptin levels and neural FCR in the fasted and sated state and the association between meal-induced changes in ghrelin and neural FCR, and in how far these associations are related to BMI and HOMA-IR...

Obesity is highly prevalent in patients with schizophrenia and, in association with metabolic syndrome, contributes to premature deaths of patients due to cardiovascular disease complications. Moreover, pharmacologic, and behavioral interventions have not stemmed the tide of obesity in schizophrenia. Therefore, novel effective interventions are urgently needed. Repetitive transcranial magnetic stimulation (rTMS) has shown efficacy for inducing weight loss in obese non-psychiatric samples but this promising intervention has not been evaluated as a weight loss intervention in patients with schizophrenia...

BACKGROUND: Neuroimaging studies suggest that appetitive drive is enhanced in obesity. OBJECTIVE: To test if appetitive drive varies in direct proportion to the level of body adiposity after accounting for genetic factors that contribute to both brain response and obesity risk. SUBJECTS/METHODS: Participants were adult monozygotic (n = 54) and dizygotic (n = 30) twins with at least one member of the pair with obesity. Body composition was assessed by dual-energy X-ray absorptiometry...

Children of overweight and obese parents have an increased risk of obesity. Little is known the neural mechanisms underlying this relationship, specifically the brain systems implicated in self-regulation of food intake. The primary goal here is to examine relationships between maternal body mass index (BMI) and brain responses to food cues in children. Seventy-six children (8.62 ± 1.02 years; 28 M,48F) were included in this study. Height and weight were assessed for children and their biological parents...