Power of mind: Attentional focus rather than palatability dominates neural responding to visual food stimuli in females with overweight

Neural correlates of naturalistic single-trial appetitive conditioning

BACKGROUND

Prior research suggests naturalistic single-trial appetitive conditioning may be a potent phenomenon in humans, capable of modulating both motivation and attention. In this study, we aimed to characterise the neural correlates of this phenomenon using functional Magnetic Resonance Imaging (fMRI) paradigms METHODS: Twenty-three healthy adults (12 males) underwent conditioning during which they ate a novel 3D object made from white chocolate (CS+) and handled a similar object made from plastic (CS-). Brain activity was recorded before and after conditioning during a passive viewing paradigm RESULTS: A naturalistic CS+ was rated as more highly craved, better-liked and elicited greater expectancies for chocolate than the CS- after conditioning. An exploration of the interaction between time (pre- and post-conditioning) and CS type (CS+, CS-) during the passive viewing task suggested enhanced activation from pre- to post-conditioning in the right superior frontal gyrus (R.SFG) in response to the CS-.

CONCLUSION

Results reveal neural correlates of single-trial appetitive conditioning and highlight a possible role of response inhibition during learning about non-rewards, perhaps optimizing motivated behaviour. These findings contribute to our understanding of the neural mechanisms underpinning rapid reward and non-reward learning, and may inform development of behavioural interventions for reward-driven overeating.

Effects of a health versus hedonic mindset on daily-life snacking behaviour

BACKGROUND

In today's obesogenic environment high-caloric palatable foods are omnipresent, making it hard for many to reach and maintain a healthy body weight. This study investigates the effects of a health versus hedonic mindset on daily-life snacking behaviour. The hypothesis is that a health mindset leads to reduced snacking behaviour compared to a hedonic mindset. This effect is expected to be most pronounced with high dietary restraint and least pronounced with high trait self-control.

METHODS

For 3 weeks, degree of craving and amount of snacks that were craved and consumed were assessed four times a day, using smartphone Ecological Momentary Assessment (EMA). A total of 111 female participants (body mass index range: 20-23.5) were randomly assigned to a 1-week health (n = 53) or hedonic (n = 58) mindset, occurring in week 2 of the EMA protocol. The mindset manipulations consisted of text messages, focusing either on the enjoyment of tasty food (hedonic) or on healthy living and eating (health).

RESULTS

contrary to our hypotheses, mindset did not affect snacking behaviour. Instead, degree of craving and intake of snacks reduced significantly over time, not moderated by mindset, dietary restraint (Restraint Scale) or trait self-control (Brief Self-Control Scale). Importantly, this was not due to reduced compliance. Possibly, the reduced craving and snacking behaviour were due to monitoring and/or socially desirable answering tendencies. Additional time point analyses showed that craving was strongest in the late afternoon (3:30-5:00 PM), and-across mindset conditions-degree of craving correlated negatively with trait self-control.

CONCLUSIONS

future studies could manipulate degree of monitoring and design individually tailored manipulations.

IT IS A MATTER OF PERSPECTIVE: ATTENTIONAL FOCUS RATHER THAN DIETARY RESTRAINT DRIVES BRAIN RESPONSES TO FOOD STIMULI

Brain responses to food are thought to reflect food's rewarding value and to fluctuate with dietary restraint. We propose that brain responses to food are dynamic and depend on attentional focus. Food pictures (high-caloric/low-caloric, palatable/unpalatable) were presented during fMRI-scanning, while attentional focus (hedonic/health/neutral) was induced in 52 female participants varying in dietary restraint. The level of brain activity was hardly different between palatable versus unpalatable foods or high-caloric versus low-caloric foods. Activity in several brain regions was higher in hedonic than in health or neutral attentional focus (p < 0.05, FWE-corrected). Palatability and calorie content could be decoded from multi-voxel activity patterns (p < 0.05, FDR-corrected). Dietary restraint did not significantly influence brain responses to food. So, level of brain activity in response to food stimuli depends on attentional focus, and may reflect salience, not reward value. Palatability and calorie content are reflected in patterns of brain activity.

Spatiotemporal profile of altered neural reactivity to food images in obesity: Reward system is altered automatically and predicts efficacy of weight loss intervention

Introduction

Obesity presents a significant public health problem. Brain plays a central role in etiology and maintenance of obesity. Prior neuroimaging studies have found that individuals with obesity exhibit altered neural responses to images of food within the brain reward system and related brain networks. However, little is known about the dynamics of these neural responses or their relationship to later weight change. In particular, it is unknown if in obesity, the altered reward response to food images emerges early and automatically, or later, in the controlled stage of processing. It also remains unclear if the pretreatment reward system reactivity to food images is predictive of subsequent weight loss intervention outcome.

Methods

In this study, we presented high-calorie and low-calorie food, and nonfood images to individuals with obesity, who were then prescribed lifestyle changes, and matched normal-weight controls, and examined neural reactivity using magnetoencephalography (MEG). We performed whole-brain analysis to explore and characterize large-scale dynamics of brain systems affected in obesity, and tested two specific hypotheses: (1) in obese individuals, the altered reward system reactivity to food images occurs early and automatically, and (2) pretreatment reward system reactivity predicts the outcome of lifestyle weight loss intervention, with reduced activity associated with successful weight loss.

Results

We identified a distributed set of brain regions and their precise temporal dynamics that showed altered response patterns in obesity. Specifically, we found reduced neural reactivity to food images in brain networks of reward and cognitive control, and elevated reactivity in regions of attentional control and visual processing. The hypoactivity in reward system emerged early, in the automatic stage of processing (< 150 ms post-stimulus). Reduced reward and attention responsivity, and elevated neural cognitive control were predictive of weight loss after six months in treatment.

Discussion

In summary, we have identified, for the first time with high temporal resolution, the large-scale dynamics of brain reactivity to food images in obese versus normal-weight individuals, and have confirmed both our hypotheses. These findings have important implications for our understanding of neurocognition and eating behavior in obesity, and can facilitate development of novel integrated treatment strategies, including tailored cognitive-behavioral and pharmacological therapies.

Food-related reward sensitivity across the spectrum of body weight and impulsive eating: Pilot findings from a multi-method approach

Overweight with and without comorbid binge-eating disorder (BED) has been associated with increased reward sensitivity, though evidence is heterogeneous. To disentangle this heterogeneity and gain insights into mechanisms of impaired reward processing, this study applied multi-method neuro-behavioural techniques. Reward sensitivity was investigated in N = 49 participants allocated to three subgroups: overweight individuals with BED (BED+, n = 17), overweight individuals without BED (BED-, n = 15), and normal-weight controls (NWC, n = 17). Applying a free exploration paradigm (food vs. non-food stimuli), eye tracking and electroencephalographic data were gathered. A valid cue before stimulus onset indicated the position of food, and the end points analysed after the cue and stimulus onset were attentional approach, attention allocation, and conflict processing (e.g., conflict between looking at the potentially rewarding food stimulus or not). The effect of negative mood was tested using mood induction. The study's main hypothesis was that individuals with overweight, particularly under negative mood, would have increased food-related reward sensitivity. All participants showed increased food-specific attentional approach (p < .001). BED + allocated more attention to food stimuli than non-food stimuli compared to the healthy control (p = .045). For individuals with overweight but without BED (BED-), results indicate that conflict processing might be prolonged after the stimulus onset (p = .011). No group-specific effect of negative mood was found. Preliminary results in overweight individuals with and without comorbid BED suggest that food stimuli are generally rewarding stimuli, but even more so for participants with binge eating psychopathology. Prolonged conflict processing during the confrontation with competing food and non-food stimuli was solely found in the BED- sample and might indicate a compensation mechanism. Replication is warranted. The multi-method approach seems to be promising to give indications for the development of psychotherapeutic treatment.

Advancing the assessment of mindful eating: Exploring the psychometric properties and validating the mindful eating behaviour scale in English

Background: Mindful eating has been described as significant in motivating research and clinical outcomes in weight regulation and healthy eating. The use of psychometric tools to measure mindful eating is problematic, with results often leading to interpretations that are not reflective of mindful eating theory and fundamentals of mindfulness. Aim: In this research, we explored the Mindful Eating Behaviour Scale (MEBS) within a British sample to validate the factorial structure, and widen the use of a scale that appears appropriate for measuring mindful eating. Methods: A community sample (n = 742) was recruited via social media, and the findings supported the factorial structure proposed through the original Dutch sample. Predictive validity was also assessed, with the scale and subscales predicting fat and sugar consumption. Results: Cronbach's α values were acceptable and similar to the original findings, also supporting the internal consistency of the scale. Conclusion: While factorial structure, predictive validity and internal consistency propose a scale that can be adopted with English speaking populations, we propose the potential of furthering scientific inquiry on mindful eating research by highlighting the behavioural aspects of the scale.

More complex than you might think: Neural representations of food reward value in obesity

Obesity reached pandemic proportions and weight-loss treatments are mostly ineffective. The level of brain activity in the reward circuitry is proposed to be proportionate to the reward value of food stimuli, and stronger in people with obesity. However, empirical evidence is inconsistent. This may be due to the double-sided nature of high caloric palatable foods: at once highly palatable and high in calories (unhealthy). This study hypothesizes that, viewing high caloric palatable foods, a hedonic attentional focus compared to a health and a neutral attentional focus elicits more activity in reward-related brain regions, mostly in people with obesity. Moreover, caloric content and food palatability can be decoded from multivoxel patterns of activity most accurately in people with obesity and in the corresponding attentional focus. During one fMRI-session, attentional focus (hedonic, health, neutral) was manipulated using a one-back task with individually tailored food stimuli in 32 healthy-weight people and 29 people with obesity. Univariate analyses (p < 0.05, FWE-corrected) showed that brain activity was not different for palatable vs. unpalatable foods, nor for high vs. low caloric foods. Instead, this was higher in the hedonic compared to the health and neutral attentional focus. Multivariate analyses (MVPA) (p < 0.05, FDR-corrected) showed that palatability and caloric content could be decoded above chance level, independently of either BMI or attentional focus. Thus, brain activity to visual food stimuli is neither proportionate to the reward value (palatability and/or caloric content), nor significantly moderated by BMI. Instead, it depends on people's attentional focus, and may reflect motivational salience. Furthermore, food palatability and caloric content are represented as patterns of brain activity, independently of BMI and attentional focus. So, food reward value is reflected in patterns, not levels, of brain activity.

Changing the visualization of food to reduce food cue reactivity: An event-related potential study

Visual food cues automatically capture our attention. Moreover, food cue exposure is associated with an increased desire to eat (craving) and food consumption. We attempted to reduce the attentional bias to images depicting a specific food (M&Ms), craving, and consumption through mental imagery in a sample of 98 females (mean age = 23.82 years). The participants either listened to a guided imagery script that described the crushing of M&Ms to reduce the appetitive value of the chocolates, or they envisioned the sorting of M&Ms, or marbles (as control conditions). Afterward, participants were presented with images of M&Ms (not crushed) and marbles while their electroencephalogram, craving ratings, and M&M consumption were measured. The visualization of crushing M&Ms was associated with increased early (P200) and late positivity (P300, early LPP) to M&M pictures, which indicate automatic (P200/P300) and deliberate attention (LPP). M&M sorting increased craving but did not influence M&M consumption. Our findings show that imaginary M&M crushing cannot reduce attention to M&M images and even has the opposite of the intended effect.

Neural Correlates of Food Cue Exposure Intervention for Obesity: A Case-Series Approach

Background

People with overweight have stronger reactivity (e.g., subjective craving) to food cues than lean people, and this reactivity is positively associated with food intake. Cue reactivity is a learned response that can be reduced with food cue exposure therapy.

Objectives

It was hypothesized that participants after food cue exposure therapy would show reduced neural activity in brain regions related to food cue reactivity and increased neural activity in brain regions related to inhibitory-control as compared to participants receiving a control lifestyle intervention.

Method

Neural activity of 10 women with overweight (BMI ≥ 27 kg/m²) in response to individually tailored visually presented palatable high-caloric food stimuli was examined before vs. after a cue exposure intervention (n = 5) or a control lifestyle (n = 5) intervention. Data were analyzed case-by-case.

Results

Neural responses to food stimuli were reduced in food-cue-reactivity-related brain regions after the lifestyle intervention in most participants, and generally not after the cue exposure therapy. Moreover, cue exposure did not lead to increased activity in inhibitory-control-related brain regions. However, decreased neural activity after cue exposure was found in most participants in the lateral occipital complex (LOC), which suggests a decreased visual salience of high-caloric food stimuli.

Conclusion

Receiving a cue exposure therapy did not lead to expected neural responses. As cue exposure relies on inhibitory learning mechanisms, differences in contexts (e.g., environments and food types) between the intervention setting and the scanning sessions may explain the general lack of effect of cue-exposure on neural activity.