Posterior resting state EEG asymmetries are associated with hedonic valuation of food

Contrasting frontal cortical responses to food versus money rewards across BMI groups

Previous research has linked obesity with an altered perception of rewards. This study aimed to contrast frontal cortical activities across body mass index (BMI) groups, in responding to differential rewards (monetary versus food). A total of 60 male participants (27.43 ± 6.07 years of age; 21 normal weight [BMI: 18.5-24.9 kg·m-2]; 20 overweight [BMI: 25.0-29.9 kg·m-2]; and 19 individuals with obesity [BMI ≥ 30 kg·m-2]) were tested for their response bias towards food and money rewards using the Probabilistic Reward Task (PRT), while their frontal cortical responses were recorded using electroencephalography (EEG). The feedback-related negativity (FRN), a reliable measure of reward valuation and learning, was calculated for food (FRN(Food)) and money (FRN(Money)). Results indicate a left-lateralised frontal cortical activity associated with the food reward condition, in the group of overweight and obesity. In contrast, a right-lateralisation was observed in the money reward condition only in the group with obesity. More specifically, FRN(Food) was shown to significantly differ between left and right frontal cortical areas among individuals with obesity (p = 0.035) and overweight (p = 0.012), but not in normal-weight individuals (p = 0.153). Additionally, results revealed that FRN(Food) and FRN(Money) were significantly different for individuals with obesity (p = 0.019), but such a significant difference was not evident in the overweight and normal-weight individuals (p ≥ 0.05). These findings offer intriguing new insights into neuropsychological differentiation across BMI groups, adding to the understanding of obesity-related behaviour.

The effects of prefrontal vs. parietal cortex transcranial direct current stimulation on craving, inhibition, and measures of self-esteem

While prefrontal cortex dysfunction has been implicated in high food cravings, other cortical regions, like the parietal cortex, are potentially also involved in regulating craving. This study explored the effects of stimulating the inferior parietal lobule (IPL) and dorsolateral prefrontal cortex (DLPFC) on food craving state and trait. Transcranial direct current stimulation (tDCS) was administered at 1.5 mA for 5 consecutive days. Participants received 20 min of IPL, DLPFC, or sham stimulation (SHAM) each day which consisted of two rounds of 10-min stimulation, divided by a 10-min mindfulness task break. In addition, we studied inhibition and subjective psychological aspects like body image and self-esteem state and trait. To decompose immediate and cumulative effects, we measured the following on days 1 and 5: inhibition through the Go/No-go task; and food craving, self-esteem, and body appreciation through a battery of questionnaires. We found that false alarm errors decreased in the participants receiving active stimulation in the DLPFC (DLPFC-group). In contrast, false alarm errors increased in participants receiving active stimulation in the IPL (IPL-group). At the same time, no change was found in the participants receiving SHAM (SHAM-group). There was a trending reduction in craving trait in all groups. Momentary craving was decreased in the DLPFC-group and increased in IPL-group, yet a statistical difference was not reached. According to time and baseline, self-esteem and body perception improved in the IPL-group. Furthermore, self-esteem trait significantly improved over time in the DLPFC-group and IPL-group. These preliminary results indicate that tDCS modulates inhibition in frontoparietal areas with opposite effects, enhancing it in DLPFC and impairing it in IPL. Moreover, craving is moderately linked to inhibition, self-esteem, and body appreciation which seem not to be affected by neuromodulation but may rely instead on broader regions as more complex constructs. Finally, the fractionated protocol can effectively influence inhibition with milder effects on other constructs.

Dynamic Functional Connectivity of Emotion Processing in Beta Band with Naturalistic Emotion Stimuli

While naturalistic stimuli, such as movies, better represent the complexity of the real world and are perhaps crucial to understanding the dynamics of emotion processing, there is limited research on emotions with naturalistic stimuli. There is a need to understand the temporal dynamics of emotion processing and their relationship to different dimensions of emotion experience. In addition, there is a need to understand the dynamics of functional connectivity underlying different emotional experiences that occur during or prior to such experiences. To address these questions, we recorded the EEG of participants and asked them to mark the temporal location of their emotional experience as they watched a video. We also obtained self-assessment ratings for emotional multimedia stimuli. We calculated dynamic functional the connectivity (DFC) patterns in all the frequency bands, including information about hubs in the network. The change in functional networks was quantified in terms of temporal variability, which was then used in regression analysis to evaluate whether temporal variability in DFC (tvDFC) could predict different dimensions of emotional experience. We observed that the connectivity patterns in the upper beta band could differentiate emotion categories better during or prior to the reported emotional experience. The temporal variability in functional connectivity dynamics is primarily related to emotional arousal followed by dominance. The hubs in the functional networks were found across the right frontal and bilateral parietal lobes, which have been reported to facilitate affect, interoception, action, and memory-related processing. Since our study was performed with naturalistic real-life resembling emotional videos, the study contributes significantly to understanding the dynamics of emotion processing. The results support constructivist theories of emotional experience and show that changes in dynamic functional connectivity can predict aspects of our emotional experience.

Combined effects of tangerine oil vapour mixed with banana flavour to enhance the quality and flavour of 'Hom Thong' bananas and evaluating consumer acceptance and responses using electroencephalography (EEG)

The objectives of this study were to investigate the effect of tangerine oil (TO) at 25, 50 and 75 µL mixed with banana flavour (BF) at 25, 50 and 75 µL to protect the quality and enhance the flavour of bananas. Then, 25 µL TO + BF 50 µL were selected for studying the quality of bananas stored at 13 °C ±   2 °C for 7 days, and was used to test consumer brain responses using an electroencephalography (EEG). Results showed that mould grew and decomposition occurred in 10 and 50% of the 25 µL TO + 50 µL BF mixture and control, respectively, after 7 days. Furthermore, this ratio increased ripening by having higher L*, b*, firmness and total soluble solid than the control (p < 0.05), whereas titratable acidity and pH were maintained (p > 0.05). The EEG demonstrated that consumption of TO-treated banana could increase brain alertness using stimulating the beta wave activity on banana stimulations for human brain. Limonene, one of the main components of TO, was found in the flesh of treated banana after storage for 4 weeks and possibly interacted with other components to improve antifungal activity and brain response.

“Sound” Decisions: The Combined Role of Ambient Noise and Cognitive Regulation on the Neurophysiology of Food Cravings

Our ability to evaluate long-term goals over immediate rewards is manifested in the brain’s decision circuit. Simplistically, it can be divided into a fast, impulsive, reward “system 1” and a slow, deliberate, control “system 2.” In a noisy eating environment, our cognitive resources may get depleted, potentially leading to cognitive overload, emotional arousal, and consequently more rash decisions, such as unhealthy food choices. Here, we investigated the combined impact of cognitive regulation and ambient noise on food cravings through neurophysiological activity. Thirty-seven participants were recruited for an adapted version of the Regulation of Craving (ROC) task. All participants underwent two sessions of the ROC task; once with soft ambient restaurant noise (∼50 dB) and once with loud ambient restaurant noise (∼70 dB), while data from electroencephalography (EEG), electrodermal activity (EDA), and self-reported craving were collected for all palatable food images presented in the task. The results indicated that thinking about future (“later”) consequences vs. immediate (“now”) sensations associated with the food decreased cravings, which were mediated by frontal EEG alpha power. Likewise, “later” trials also increased frontal alpha asymmetry (FAA) —an index for emotional motivation. Furthermore, loud (vs. soft) noise increased alpha, beta, and theta activity, but for theta activity, this was solely occurring during “later” trials. Similarly, EDA signal peak probability was also higher during loud noise. Collectively, our findings suggest that the presence of loud ambient noise in conjunction with prospective thinking can lead to the highest emotional arousal and cognitive load as measured by EDA and EEG, respectively, both of which are important in regulating cravings and decisions. Thus, exploring the combined effects of interoceptive regulation and exteroceptive cues on food-related decision-making could be methodologically advantageous in consumer neuroscience and entail theoretical, commercial, and managerial implications.

Parsing the link between reinforcement sensitivity theory and eating behavior: A systematic review

The Reinforcement Sensitivity Theory (RST) is a widely studied psychobiological model of personality. RST factors seem to influence eating behavior, but how these personality traits are associated with distinct features of eating behavior is still unclear. In the present systematic review, we analyzed the relationship between RST personality factors and eating behavior using a parsing approach in which BMI-related results, self-reported results, and behavioral results were distinguished. Our analysis revealed that reward and punishment sensitivity seem to correlate and influence distinct features of eating behavior. The association between BMI and RST factors was uncertain, but nonlinear associations between reward sensitivity and weight need further testing. Reward sensitivity was linked to most eating behavior phenotypes (e.g., emotional eating and restrained eating), but only punishment sensitivity was primarily correlated with eating pathology. Reward sensitivity was the main factor linked with reactivity to food stimuli on many behavioral measures. The neurobiological personality factors of RST offer parsimonious concepts to understand eating behavior outcomes and the differential relationships observed are useful to translational research.

Prisoners of Addictive Cues: Biobehavioral Markers of Overweight and Obese Adults with Food Addiction

Obesity is associated with food and eating addiction (FA), but the biobehavioral markers of this condition are poorly understood. To characterize FA, we recruited 18 healthy controls and overweight/obese adults with (n = 31) and without (n = 17) FA (H-C, FAOB, NFAOB, respectively) to assess alpha brain asymmetry at rest using electroencephalogram; event-related potentials following exposure to high-calorie food (HCF), low-calorie food (LCF), and nonfood (NF) images in a Stroop paradigm; reaction time reflective of the Stroop bias; and symptoms of depression and disordered eating behavior. The FAOB group had the greatest emotional and uncontrollable eating, depressive, and binge-eating symptoms. The FAOB group displayed lower resting left alpha brain asymmetry than that of the NFAOB group. Differently from the other groups, the FAOB group presented attenuated Stroop bias following exposure to HCF relative to NF images, as well as a lower late positive potential component (LPPb; 450-495 ms) in both frontal and occipital regions. In the total cohort, a correlation was found between the Stroop bias and the LPPb amplitude. These results point to biobehavioral hypervigilance in response to addictive food triggers in overweight/obese adults with FA. This resembles other addictive disorders but is absent in overweight/obesity without FA.

Beyond frontal alpha: investigating hemispheric asymmetries over the EEG frequency spectrum as a function of sex and handedness

Frontal alpha EEG asymmetry, an indirect marker of asymmetries in relative frontal brain activity, are widely used in research on lateralization of emotional processing. While most authors focus on frontal electrode pairs (e.g., F3/F4 or F7/F8), several recent studies have indicated that EEG asymmetries can also be observed outside the frontal lobe and in frequency bands other than alpha. Because the focus of most EEG asymmetry research is on the correlations between asymmetry and other traits, much less is known about the distribution of patterns of asymmetry at the population level. To systematically assess these asymmetries in a representative sample, we determined EEG asymmetries across the head in the alpha, beta, delta and theta frequency bands in 235 healthy adults. We found significant asymmetries in all four frequency bands and across several brain areas, indicating that EEG asymmetries are not limited to frontal alpha. Asymmetries were not modulated by sex. They were modulated by direction of hand preference, with stronger right-handedness predicting greater right (relative to left) alpha power, or greater left (relative to right) activity. Taken together, the present results show that EEG asymmetries other than frontal alpha represent markers of asymmetric brain function that should be explored further.