Whether, how, and which cognitive factors modulate the development of secondary hypersensitivity/hyperalgesia following central sensitization is not fully understood. Here we tested, in three subsequent experiments, whether being engaged in non-pain related cognitive demanding tasks: i) lessens the amount of hypersensitivity developed after an experimental procedure sensitizing nociceptive pathways; ii) modulates cortical responses to somatosensory stimuli (measured by electroencephalography, EEG). In the first experiment we validated a novel model in humans using low frequency stimulation (LFS) of the skin and demonstrated that it was able to successfully induce hypersensitivity to mechanical pinprick stimuli in the area surrounding the sensitized site. In the second and third experiments we engaged participants in tasks of increasing difficulty (the Eriksen Flanker Task in experiment 2, and a modified N-back task in experiment 3). We observed that hypersensitivity to mechanical stimuli still developed in experiment 2, i.e. the pinprick stimuli applied on the sensitized arm were perceived as more intense after LFS. In contrast, no statistically significant enhancement of mechanical hypersensitivity was observed in experiment 3, indicating that, at the group level, being engaged in a difficult N-back task may interfere with the development of mechanical hypersensitivity. Contrary to previous studies, which have used different methods to induce sensitization, we did not observe any increase in the cortical response to somatosensory stimuli applied on the sensitized arm. We conclude that i) the development of pinprick hypersensitivity is modulated by the concomitant execution of a difficult N-back task, and ii) the enhancement of cortical responses to somatosensory stimuli is related to the method used to induce central sensitization.

In today's society, obesity rates are rising as food intake is no longer only a response to physiological hunger signals that ensure survival. Eating can represent a reward, a response to boredom, or stress reduction and emotion regulation. While most people decrease food intake in response to stress or negative emotions, some do the opposite. Yet, it is unclear who shows emotional overeating under which circumstances. Emotion regulation theories describe emotional overeating as a learned strategy to down-regulate negative emotions. Cognitive theories, by contrast, attribute emotional overeating to perceived diet breaches in individuals who chronically attempt to diet. After consuming "forbidden foods", they eat more than individuals who do not restrict their food intake. This laboratory study investigated emotional overeating by exposing individuals to a personalized emotion induction while showing images of palatable foods. Outcome variables indexed cue reactivity to food images through picture ratings (valence, desire to eat), facial expressions (electromyography of the corrugator supercilii muscle), and brain reactivity by detecting event-related potentials (ERPs) by means of electroencephalography (EEG). The influence of emotion condition (negative, neutral) and individual differences (self-reported trait emotional and restrained eating) on outcome variables was assessed. Valence ratings and appetitive reactions of the corrugator muscle to food pictures showed a relative increase in the negative condition for individuals with higher emotional eating scores, with the opposite pattern in lower scores. Desire to eat ratings showed a similar pattern in individuals who showed a strong response to the emotion induction manipulation, indicative of a dose-response relationship. Although no differences between conditions were found for ratings or corrugator activity with restrained eating as a predictor, an ERP at P300 showed increased activation when viewing food compared to objects in the negative condition. Findings support emotion regulation theories: Emotional eaters showed an appetitive reaction in rating patterns and corrugator activity. EEG findings (increased P300)

In a feasibility trial comparing two forms of combined inhibitory control training and goal planning (i.e., food-specific and general) among patients with bulimia nervosa (BN) and binge eating disorder (BED), we found evidence of symptomatic benefit, with stronger effects among participants receiving a food-specific intervention. The aim of the present study was to examine changes in behavioral outcomes and event-related potentials (ERPs; N2 and P3 amplitudes) from baseline to post-intervention that might suggest the mechanisms underpinning these effects. Fifty-five participants completed go/no-go tasks during two electroencephalography (EEG) sessions, at baseline and post-intervention. The go/no-go task included "go" cues to low energy-dense foods and non-foods, and "no-go" cues to high energy-dense foods and non-foods. Datasets with poor signal quality and/or outliers were excluded, leaving 48 participants (N = 24 BN; N = 24 BED) in the analyses. Participants allocated to the food-specific, compared to the general intervention group, showed significantly greater reductions in reaction time to low energy-dense foods, compared to non-foods, by post-intervention. Commission errors significantly increased from baseline to post-intervention, regardless of stimulus type (food vs. non-food) and intervention group (food-specific vs. general). There were no significant changes in omission errors. P3 amplitudes to "no-go" cues marginally, but non-significantly, decreased by post-intervention, but there was no significant interaction with stimulus type (high energy-dense food vs. non-food) or intervention group (foodspecific vs. general). There were no significant changes in N2 amplitudes to "no-go" cues, N2 amplitudes to "go" cues, or P3 amplitudes to "go" cues from baseline to post-intervention. Training effects were only marginally captured by these event-related potentials. We discuss limitations to the task paradigm, including its two-choice nature, ease of completion, and validity, and give recommendations for future research exploring ERPs using inhibitory control paradigms.

No abstract

Objective: Theories on emotional eating are central to our understanding of etiology, maintenance, and treatment of binge eating. Yet, findings on eating changes under induced negative emotions in binge-eating disorder (BED) are equivocal. Thus, we studied whether food-cue reactivity is potentiated under negative emotions in BED, which would point toward a causal role of emotional eating in this disorder.Methods: Patients with BED (n = 24) and a control group without eating disorders (CG; n = 69) completed a food picture reactivity task after induction of negative versus neutral emotions. Food-cue reactivity (self-reported food pleasantness, desire to eat [DTE], and corrugator supercilii muscle response, electromyogram [EMG]) was measured for low-and high-caloric food pictures.Results: Patients with BED showed emotion-potentiated food-cue reactivity compared to controls: Pleasantness and DTE ratings and EMG response were increased in BED during negative emotions. This was independent of caloric content of the images.Conclusions: Food-cue reactivity in BED was consistent with emotional eating theories and points to a heightened response to all foods regardless of calorie content.The discrepancy of appetitive ratings with the aversive corrugator response points to ambivalent food responses under negative emotions in individuals with BED.