Virtual reality assessment of a high-calorie food bias: Replication and food-specificity in healthy participants.

BACKGROUND: Theoretical models and behavioural studies indicate faster approach behaviour for high-calorie food (approach bias) among healthy participants. A previous study with Virtual Reality (VR) and online motion-capture quantified this approach bias towards food and non-food cues in a controlled VR environment with hand movements. The aim of this study was to test the specificity of a manual approach bias for high-calorie food in grasp movements compared to low-calorie food and neutral objects of different complexity, namely, simple balls and geometrically more complex office tools. METHODS: In a VR setting, healthy participants (N = 27) repeatedly grasped or pushed high-calorie food, low-calorie food, balls and office tools in randomized order with 30 item repetitions. All objects were rated for valence and arousal. RESULTS: High-calorie food was less attractive and more arousing in subjective ratings than low-calorie food and neutral objects. Movement onset was faster for high-calorie food in push-trials, but overall push responses were comparable. In contrast, responses to high-calorie food relative to low-calorie food and to control objects were faster in grasp trials for later stages of interaction (grasp and collect). Non-parametric tests confirmed an approach bias for high-calorie food. CONCLUSION: A behavioural bias for food was specific to high-calorie food objects. The results confirm the presence of bottom-up advantages in motor-cognitive behaviour for high-calorie food in a non-clinical population. More systematic variations of object fidelity and in clinical populations are outstanding. The utility of VR in assessing approach behaviour is confirmed in this study by exploring manual interactions in a controlled environment.

High-definition turns timing-dependent: Different behavioural consequences during and following cathodal high-definition transcranial direct current stimulation (HD tDCS) in a magnitude classification task.

Neuromodulation with transcranial direct current stimulation (tDCS) can transiently alter neural activity, but its spatial precision is low. High-definition (HD) tDCS was introduced to increase spatial precision by placing additional electrodes over the scalp. Initial evaluations of HD tDCS indicated polarity-specific neurophysiological effects-similar to conventional tDCS albeit with greater spatial precision. Here, we compared the effects of cathodal tDCS or HD tDCS in a 4 × 1 configuration over prefrontal cortex (PFC) regions on behavioural outcomes in a magnitude classification task. We report results on overall performance, on the numerical distance effect as a measure of numerical processing, and on the spatial-numerical associations of response codes (SNARC) effect, which was previously affected by prefrontal tDCS. Healthy volunteers (n = 68) received sham or cathodal HD tDCS at 1 mA over the left dorsolateral prefrontal cortex (DLPFC) or the left inferior frontal gyrus (IFG). Results were compared to an identical protocol with conventional cathodal tDCS to the left PFC versus sham (n = 64). Mixed effects models showed performance gains relative to sham tDCS in all conditions after tDCS (i.e. 'offline'), whereas montages over PFC and DLPFC already showed performance gains during tDCS (i.e. 'online'). In contrast to conventional tDCS, HD tDCS did not reduce the SNARC effect. Neither condition affected numerical processing, as expected. The results suggest that HD tDCS with cathodal polarity might require further adjustments (i.e. regarding tDCS intensity) for effective modulations of cognitive-behavioural performance, which could be achieved by individualised current density in electric field modelling.

Regional specificity of cathodal transcranial direct current stimulation effects on spatial-numerical associations: Comparison of four stimulation sites.

Neuromodulation with transcranial direct current stimulation (tDCS) is an increasingly popular research tool to experimentally manipulate cortical areas and probe their causal involvements in behavior, but its replicability and regional specificity are not clear. This registered report investigated cathodal tDCS effects on spatial-numerical associations (i.e., the SNARC effect), the numerical distance effect (NDE), and inhibitory control (i.e., stop-signal reaction time; SSRT). Healthy adults (N = 160) were randomly assigned to one of five groups to receive sham tDCS or 1 mA cathodal tDCS to one of four stimulation sites (left/right prefrontal cortex [PFC], left/right posterior parietal cortex) with extracephalic return. We replicated that cathodal tDCS over the left PFC reduced the SNARC effect compared to sham tDCS and to tDCS over the left parietal cortex. However, neither NDE nor SSRT were modulated in the main analyses. Post hoc contrasts and exploratory analyses showed that cathodal tDCS over the right PFC had a time-dependent effect by delayed practice-related improvements in SSRT. Math anxiety moderated changes in the NDE in the groups receiving tDCS to the right parietal cortex. With few exceptions, the replicability and regional specificity of tDCS effects on behavior were weak and partially moderated by individual differences. Future research needs to characterize the parameter settings for effective neuromodulation.

Persistent avoidance of virtual food in anorexia nervosa-restrictive type: Results from motion tracking in a virtual stopping task.

OBJECTIVE: Food avoidance is central to patients with anorexia nervosa-restrictive type (AN-R). Competing accounts in experimental psychopathology research suggest that food avoidance may result from automatic, habitual responses or from elevated inhibitory control abilities. This study investigated behavioral trajectories of food avoidance in a novel virtual reality stopping task. METHOD: Sixty patients with AN-R and 29 healthy controls with normal weight were investigated using a novel, kinematic task in virtual reality. We recorded spatial displacement in stop- and go-trials to virtual food and control objects. Inhibitory control abilities were operationalized by the VR task in stopping performance (i.e., interrupted movement in stop-trials), whereas we also measured habitual avoidance of virtual food across both go- and stop-trials (i.e., delayed movement relative to nonfood objects). RESULTS: In patients with AN-R, hand displacements were shorter to food versus nonfood across stop- and go-trials, reflected in a Stimulus × Group interaction. Healthy controls showed no differences. Importantly, the food-specific effect in AN-R was identical across stop- and go-trials, indicating habitual food avoidance. Moreover, stop error rates (i.e., stop-trials with response) were lower in patients with AN-R. DISCUSSION: The findings suggest food-specific habitual avoidance and heightened generalized inhibitory control in AN-R. The continuously delayed displacements during active hand movements across stop- and go-trials indicated the persistence of patients' avoidance of food. PUBLIC SIGNIFICANCE: Experimental research investigates the mechanisms underlying mental disorders such as anorexia nervosa. In this study, we measured interrupted hand movements in response to food pictures or neutral pictures (shoes) in patients with anorexia nervosa and healthy controls. A virtual reality scenario was used. Findings indicated that patients were slower at approaching food, interrupted or not. Key mechanisms of food avoidance can be translated into habit-based treatment options in future research.

Body Dissatisfaction Directs Avatar Perception: Embodiment and Selective Visual Attention in Body Mass-Modified Self-Avatars.

Human agents immersed in metaverse technologies such as virtual reality (VR) are routinely disconnected from their actual physical appearance and embodied in another virtual body, referred to as self-avatar. Such body transformations can have implications for patients with eating disorders, or persons with extreme body dissatisfaction (BD). Changes in BD, weight anxiety, or body image are theoretically linked to visual selective attention, which can be measured with eye tracking. In the present study, 43 women with high or low BD were immersed in animated body weight-manipulated self-avatars in VR. Before a brief mirror exposure with their self-avatars, they experienced synchronous visuomotor and visuo-tactile contingencies in VR to increase embodiment, delivered through small movement exercises with real-time animation from first-person perspective and passive haptics. In a crossover study design, self-avatar weight was manipulated (normal weight vs. overweight) in both groups (low BD vs. high BD), and subjective experience was assessed before and after exposure. In contrast to our hypotheses, BD was not affected by the self-avatar condition. Embodiment decreased during mirror exposure, possibly due to the avatars wearing head-mounted displays. Interestingly, disembodiment was stronger in women with low BD. Furthermore, eye tracking showed that participants with high BD looked longer at weight-related body parts when immersed in the overweight self-avatar, whereas participants with low BD looked longer at weight-related body parts when immersed in the normal weight self-avatar. Overall, the results support body-specific visual attention and suggest that particularly participants with low BD show stronger disembodiment during self-avatar mirror exposure, possibly alleviating momentary body experience. Preregistration: https://doi.org/10.23668/psycharchives.4949.

Does inhibitory control spill over to eating behaviors? Two preregistered studies of inhibitory spillover effects on food intake and reactions to food stimuli.

Overweight and obesity are worldwide conditions associated with detrimental medical and psychosocial outcomes. As inhibitory control deficits are thought to contribute to weight gain, they are a worthwhile target for new approaches. Previous research has shown that the execution of inhibitory control in one domain leads to a concurrent increase of inhibitory control in another domain, an effect denoted as inhibitory spillover effect (ISE). Therefore, we assumed that exertion of inhibitory control in a food-unrelated domain in overweight and normal weight individuals will decrease food intake in a simultaneous bogus taste test (BTT; study 1) as well as increase food-specific response inhibition ability in a stop signal task (SST; study 2). We assumed stronger effects in overweight individuals. In both studies ISE was induced via cognitive priming and compared to a neutral condition in a group of overweight (OW: n = 46 for study 1, n = 46 for study 2) and normal weight (NW: n = 46 for study 1, n = 46 for study 2) individuals. In the ISE condition with an inhibitory control priming task, participants had to learn and retain control-related words while simultaneously performing a BTT (study 1) or SST (study 2). In the neutral condition, participants followed the same protocol, albeit memorizing neutral (i.e., control-unrelated) words. There was no significant interaction of weight group × cognitive priming condition neither regarding food intake (study 1) nor regarding food-related response inhibition (study 2). Cognitive priming, as implemented in the present studies, does not instigate an ISE strong enough to improve inhibitory control during food intake or food-related response inhibition. Relevant practical and theoretical aspects as well as implications for future research on the ISE are discussed.

Easy to get, difficult to avoid: Behavioral tendencies toward high-calorie and low-calorie food during a mobile approach-avoidance task interact with body mass index and hunger in a community sample.

In recent years, different studies highlighted the importance of assessing behavioral tendencies toward different food stimuli in healthy and pathological samples. However, heterogeneities in experimental approaches and small sample sizes make this literature rather inconsistent. In this study, we used a mobile approach-avoidance task to investigate the behavioral tendencies toward healthy and unhealthy foods compared to neutral objects in a large community sample. The role of some contextual and stable subjective variables was also explored. The sample included 204 participants. The stimuli comprised 15 pictures of unhealthy foods, 15 pictures of healthy foods, and 15 pictures of neutral objects. Participants were required to approach or avoid stimuli by respectively pull or push the smartphone toward or away from themselves. Accuracy and reaction time of each movement were calculated. The analyses were conducted using a generalized linear mixed-effect model (GLMMs), testing the two-way interaction between the type of movement and the stimulus category and the three-way interactions between type of movement, stimulus, and specific variables (BMI, time passed since the last meal, level of perceived hunger). Our results evidenced faster approaching movement toward food stimuli but not toward neutrals. An effect of BMI was also documented: as the BMI increased, participants became slower in avoiding unhealthy compared to healthy foods, and in approaching healthy compared to unhealthy stimuli. Moreover, as hunger increased, participants became faster in approaching and slower in avoiding healthy compared to unhealthy stimuli. In conclusion, our results show an approach tendency toward food stimuli, independent from caloric content, in the general population. Furthermore, approach tendencies to healthy foods decreased with increasing BMI and increased with perceived hunger, indicating the possible influence of different mechanisms on eating-related behavioral tendencies.

Does a white bear help you eat less? The impact of the inhibitory spillover effect on eating behaviour.

OBJECTIVE: Overweight and obesity are global problems with negative physical, social, and psychological outcomes. Besides other factors, inhibitory control deficits contribute to weight gain and development of overweight. The inhibitory spillover effect (ISE) improves inhibitory control through transfer of inhibitory control capacity from one domain to an unrelated, second domain. For ISE to occur, one inhibitory control task is executed simultaneously with a second, non-control related task thereby increasing inhibitory control in this task. METHOD: In this preregistered study, we tested the ISE induced through thought suppression in contrast to a neutral task in participants with normal weight and overweight (N = 92). A simultaneously conducted bogus taste test served as outcome measure for food intake. RESULTS: We found neither an interaction effect between group affiliation and condition nor an effect of group affiliation. However, contrary to our expectations, we found higher food intake in participants with active ISE compared to the neutral task. CONCLUSIONS: This result might indicate rebound effects of applied thought suppression which led to the experience of loss of control and therefore undermined maintenance and function of the ISE. This main result was robust to all moderator variables. We elaborate further factors for the finding, theoretical implications, and future research directions.

Food induced distractibility in restrictive anorexia nervosa: Different motor patterns for different foods as revealed by a mouse tracker evaluation.

An altered automatic processing of food stimuli may contribute to the maintenance of calorie restriction in patients with restrictive Anorexia Nervosa (AN-R). The present study aimed to assess whether task-irrelevant food distractors elicited a different interference effect in the motor actions of patients with AN-R compared to healthy controls (HC). 40 patients with acute AN-R and 40 HC performed an irrelevant distractor task in which they were required to perform a reaching movement from a starting point to a green dot, while an irrelevant distractor (a high-calorie food, low-calorie food, or neutral object) was presented in the middle of the screen. Mouse trajectories and response times (RT) were recorded. The analyses conducted on the kinematic variables revealed that while the trajectories of HC veered similarly toward the three categories of stimuli, AN-R patients showed an increased deviation toward low-calorie foods and a reduced deviation toward high-calorie foods compared to neutral objects. No significant results emerged as regards RT. The pattern of responses observed in patients with AN-R (deviation increased toward low-calorie and reduced toward high-calorie) is consistent with their eating habits and may thus represent an implicit mechanism sustaining calorie restriction in patients with AN-R.

Using preregistration as a tool for transparent fNIRS study design.

Significance: The expansion of functional near-infrared spectroscopy (fNIRS) methodology and analysis tools gives rise to various design and analytical decisions that researchers have to make. Several recent efforts have developed guidelines for preprocessing, analyzing, and reporting practices. For the planning stage of fNIRS studies, similar guidance is desirable. Study preregistration helps researchers to transparently document study protocols before conducting the study, including materials, methods, and analyses, and thus, others to verify, understand, and reproduce a study. Preregistration can thus serve as a useful tool for transparent, careful, and comprehensive fNIRS study design. Aim: We aim to create a guide on the design and analysis steps involved in fNIRS studies and to provide a preregistration template specified for fNIRS studies. Approach: The presented preregistration guide has a strong focus on fNIRS specific requirements, and the associated template provides examples based on continuous-wave (CW) fNIRS studies conducted in humans. These can, however, be extended to other types of fNIRS studies. Results: On a step-by-step basis, we walk the fNIRS user through key methodological and analysis-related aspects central to a comprehensive fNIRS study design. These include items specific to the design of CW, task-based fNIRS studies, but also sections that are of general importance, including an in-depth elaboration on sample size planning. Conclusions: Our guide introduces these open science tools to the fNIRS community, providing researchers with an overview of key design aspects and specification recommendations for comprehensive study planning. As such it can be used as a template to preregister fNIRS studies or merely as a tool for transparent fNIRS study design.

Anodal stimulation of inhibitory control and craving in satiated restrained eaters.

OBJECTIVES: Eating and weight disorders are severe and complex clinical conditions which, among other behaviors, include (attempts at) restrained eating, food avoidance, following dietary rules, and overeating. Comparable to women with obesity, restrained eaters (RE) without formal eating disorder diagnosis are worse at inhibiting their motor responses than unrestrained eaters (URE). According to neuroimaging studies, the right inferior frontal gyrus (rIFG) is involved in inhibitory control which, in turn, could be improved by neuromodulation such as anodal transcranial direct current stimulation (tDCS) across rIFG. METHODS: This double-blind sham-controlled cross-over study was conducted after a standardized breakfast. Normal-weight female RE und URE performed a stop-signal task (SST) with food and non-food stimuli during sham or anodal tDCS. Food craving, hunger, and satiety were self-reported before and after tDCS. We employed a mixed between-subjects (group: RE vs. URE) and within-subjects factorial design (tDCS: anodal tDCS vs. sham; stimuli: food vs. control pictures). RESULTS: Breakfast consumption was comparable for RE and URE, as well as craving, hunger, and thirst. Regarding inhibitory control, a significant two-way interaction between group and tDCS ermerged: RE had longer stop-signal reaction times (SSRTs) during sham tDCS, but they improved to the level of URE by application of anodal tDCS. DISCUSSION: Results replicated an inhibitory control deficit in RE with longer SSRTs compared to URE without stimulation. During anodal tDCS to the rIFG, reduced SSRTs in RE indicated an improvement in inhibitory control. The findings suggest a specificity of rIFG stimulation in at-risk groups with regards to inhibitory control irrespective of craving.

Playing with temptation: Stopping abilities to chocolate are superior, but also more extensive.

Cue-specific inhibitory control is assumed to support balanced food intake, but previous studies with established measures showed inconsistent results. We developed a novel kinematic stop task in virtual reality (VR) and report results from trajectory recordings. The primary objective of this explorative study was to assess the interrelationships between validated measures of food-related inhibitory control and novel measures from the VR task. We hypothesized that healthy female participants show worse inhibitory control when grasping attractive virtual chocolate, compared to non-edible color-and-shape matched objects. We further aimed to quantify the construct validity of kinematic measures (e.g., reaching extent/spatial displacement, movement time after stop-signal, velocity) with established measures of inhibitory control in a keyboard-based adaptive stop-signal task (SST). In total, 79 females with varying levels of chocolate craving participated in an experimental study consisting of self-report questionnaires, subjective chocolate craving, the conventional SST and the kinematic task in VR. Results showed superior stopping ability to chocolate in both tasks. In VR, participants successfully interrupted an initiated approach trajectory but terminated slightly closer to chocolate targets. Stop-signal delay (SSD) was adapted relative to movement onset and appeared later in chocolate trials, during which participants still stopped faster, as was also confirmed by shorter stop-signal reaction time (SSRT) in the conventional task. Yet, SSRT did not correlate with stopping in VR. Moreover, SSRT was related to depressive symptoms whereas measures from VR were related to chocolate craving and subjective hunger. Thus, VR stopping can provide deeper insights into healthy weight individuals' capacity to inhibit cue-specific approach behavior towards appetitive stimuli in simulated interactions. Furthermore, the results support a multi-faceted view of food-specific inhibitory control and behavioral impulsivity.

Facilitation of simultaneous control? A meta-analysis of the inhibitory spillover effect.

Impaired inhibitory control is a core transdiagnostic mechanism in psychopathology. Directly targeting inhibitory control in intervention studies has, however, produced only little improvement. Recently, promising improvements in inhibitory control were shown by capitalizing on the inhibitory spillover effect (ISE). The central requirement of ISE is a simultaneous execution of two tasks, allowing for improved inhibitory control in the target task when control is simultaneously recruited in an induction task. The magnitude of the ISE remains to be assessed. In this preregistered meta-analysis, we synthesized eligible data from studies across psychology with the central requirement of simultaneity; thus, we deliberately included also studies meeting this requirement without the explicit aim to investigate the ISE. Results confirmed previous evidence of the ISE and documented a statistically significant small effect size (g = 0.27). Of the different induction types, cognitive induction showed the largest effects, whereas physiological and attentional induction tasks were less effective. In contrast, motor induction did not result in a significant ISE. Due to high between-study heterogeneity, we analyzed several preregistered and exploratory moderators, out of which only duration of the experimental sequence, group affiliation, and planned investigation of the ISE were significant. Sensitivity analyses yielded no indication of a publication bias. Taken together, this meta-analysis suggests that the ISE is a small, but substantial and robust effect. Future research should investigate how the ISE is applied best to reap its practical value in new treatment approaches for individuals with inhibition impairments. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Gamification improves antidepressant effects of cognitive control training-A pilot trial.

Objective: Computerised cognitive trainings have been put forward to improve control over negatively biased information processing and associated depressive symptomatology. Yet, disease-related impairments of motivation and endurance, as well as insufficient accessibility hinder use of this promising therapeutic opportunity. Here, we developed an app (de:)press© ) that utilizes a cognitive control training (paced auditory serial addition task) enriched with gamification and information elements. We compared a six-week training with de:)press© to a non-gamified version (active control group). Methods: Thirty-two depressed participants were included. Each received either de:)press© or the non-gamified version and was instructed to train three times per week for two weeks. Afterwards (four weeks) they were free to train at their own discretion. Depression severity was assessed during training and two follow-up sessions. Primary endpoint was defined as difference between groups [change of Montgomery-Åsberg Depression Rating Scale (MADRS)] four weeks after end of training. Results: Depression severity decreased in both groups. At primary endpoint, MADRS scores were significantly lower in the de:)press© -group compared to the control group. No differences were observed at three months' follow-up. Intervention usability was consistently rated positively. Participants who had trained with de:)press© maintained the recommended training frequency without further prompting. Besides transient fatigue or frustration, no adverse effects were observed. Conclusion: This pilot demonstrates that gamification and information elements can substantially increase cognitive control training efficacy in alleviating depressive symptoms. Moreover, it provides first evidence for the feasibility and efficacy of de:)press© as an add-on intervention to treat depression. Clinical trial registration: The study is registered under ClinicalTrials.gov, identifier: NCT04400162.

Implicit measures of alcohol approach and drinking identity in alcohol use disorder: A preregistered double-blind randomized trial with cathodal transcranial direct current stimulation (tDCS).

Alcohol use disorder (AUD) is a severe and widespread mental disorder with a huge negative impact on the social, economic and health dimensions. The identification of risk factors for the development of AUD and for relapse in existing AUD are crucial for prevention and treatment approaches. Alcohol-related implicit associations have been shown to contribute to drinking and might partially explain sudden relapses. The aims of this study are to investigate implicit associations in abstinent AUD patients and to test whether cathodal transcranial direct current stimulation (tDCS) modulates implicit associations. We measured performance in two alcohol-related implicit association tests (IATs) and two control tasks (flower-insect IAT, Stroop task) in 27 abstinent AUD patients with 31.5 (SD = 36) days of abstinence on average. During the execution of the tasks, we applied 1 mA cathodal or sham tDCS over the left dorsolateral prefrontal cortex (dlPFC) in a sham-controlled within-subject design. Results show an implicit bias of alcohol avoidance and implicit nondrinking identity for abstinent AUD patients. Cathodal tDCS modulated neither alcohol-related implicit associations nor the control tasks. This study complements knowledge about implicit alcohol-related association in AUD patients and shows no effect of a neuromodulatory intervention to alter implicit associations with the present parameters.

More focal, less heterogeneous? Multi-level meta-analysis of cathodal high-definition transcranial direct current stimulation effects on language and cognition.

High-definition transcranial direct current stimulation (HD-tDCS) is a relatively focal, novel non-invasive brain stimulation method with the potential to investigate the causal contributions of specific cortical brain regions to language and cognition. Studies with HD-tDCS typically employ a 4 × 1 electrode design with a single central target electrode surrounded by four return electrodes, among which return current intensity is evenly distributed. With cathodal HD-tDCS, neural excitability in the target region is assumed to be reduced, which offers interesting perspectives for neuropsychological research and interventions. This multi-level meta-analysis compiles published studies using cathodal HD-tDCS in 4 × 1 configuration to modulate cognition and behavior. Regarding HD-tDCS, 77 effect sizes were gathered from 11 eligible reports. We extended this database with 52 effect sizes from 11 comparable reports using conventional tDCS with cathodal polarity. We observed no significant overall effect and no moderation by within-study and between-study variables in HD. In the extended analysis, results suggested a non-linear moderation of cathodal tDCS effects by intensity, driven by negative effect sizes at 1.5 mA. However, studies varied tremendously in task parameters, outcomes, and even technical parameters. Interestingly, within-study heterogeneity exceeded between-study heterogeneity in the present sample, and moderators hardly reduced the residual heterogeneity. Across domains and configurations, both positive and negative effect sizes are possible. We discuss the findings in relation to conventional cathodal tDCS and the framework of polarity specificity. Fundamental aspects of cathodal HD-tDCS are still to be addressed in future research.

Spotlight on the Left Frontal Cortex: No Evidence for Response Inhibition from Cathodal High-Definition transcranial Direct Current Stimulation over Left Inferior Frontal Gyrus or Left Dorsolateral Prefrontal Cortex.

Inhibitory control functions draw on a fronto-basal network with central cortical hubs at the right inferior frontal gyrus (IFG) and the pre-SMA. However, few neuropsychological studies investigated the role of brain regions in the left frontal cortex and some previous evidence from bilateral studies remained inconclusive. This study presents a systematic investigation with high-definition transcranial direct current stimulation (HD tDCS) in a focal 4 × 1 configuration, which was used to target the left IFG or the left dorsolateral prefrontal cortex (DLPFC) with 1-mA active or sham cathodal HD tDCS. Healthy participants were randomized into three groups. We analyzed performance in an adaptive stop-signal task to quantify inhibitory control before (baseline), during cathodal HD tDCS (on-line), and after cathodal HD tDCS (off-line) to either left IFG, left DLPFC, or sham. Results from 67 participants and Bayesian analyses indicated moderate evidence against an effect of cathodal tDCS (left DLPFC and left IFG compared with sham) regardless of timing, that is, on-line or off-line cathodal HD tDCS. The study results are examined in view of previous neuropsychological and neurostimulation studies with bilateral and unilateral cathodal tDCS in healthy and patient samples. Theoretically, our results are compatible with a right-lateralization of response inhibition functions and suggest a negligible role of the left frontal hemisphere in healthy participants, but more stimulation parameters can be still explored in the left hemisphere. In line with previous studies, right inferior frontal gyrus seems a more promising target to investigate or alleviate response inhibition with tDCS.

Incentive sensitization in binge behaviors: A mini review on electrophysiological evidence.

INTRODUCTION: Binge behavior not only refers to the consumption of substances such as alcohol or food, but is also used in relation to gaming, watching and gambling. Dependent on context it makes for a widespread, benign recreational activity or can pose a serious mental health problem with deleterious consequences. Incentive sensitization theory describes the attribution of salience towards stimuli strongly associated with dopamine-mediated reward as a result of repeated consumption. The sensitized neural networks cause cue-triggered craving and excessive desire, but thus, this mechanism may also be applicable to stimulus-induced behaviors not associated with classical withdrawal symptoms. Event-related potentials (ERP) are a useful method of examining motivated attention towards incentive stimuli. This mini review aims to synthesize ERP findings from different types of binge behaviors in order to compare cue-reactivity to incentive stimuli. METHODS: Studies investigating binge drinking, binge eating as well as binge watching, gaming and gambling were screened. To limit the influence of concurrent task demands, ERP studies applying picture viewing paradigms with incentive stimuli were selected. RESULTS: Across binge behaviors, evidence on altered mid-latency ERPs has been mixed. However, studies investigating later stages of attentional processes more consistently find enlarged P300 and late positive potentials (LPP) amplitudes to relevant cues. CONCLUSION: An altered attentional processing of incentive stimuli reflecting motivated attention is in line with incentive sensitization theory. Considering the limited number of studies, especially regarding binge behaviors not involving substances, more research is needed to attain a more thorough understanding of incentive sensitization across binge behaviors.

Mind the food: behavioural characteristics and imaging signatures of the specific handling of food objects.

In our world with nearly omnipresent availability of attractive and palatable high-calorie food, the struggle against overweight and obesity is a major individual and public health challenge. Preference for unhealthy food and eating-related habits have a strong influence on health, suggesting that high-calorie food triggers fast and near-automatic reaching and grasping movements. Therefore, it is important to better understand the specific neural mechanisms that control the handling of food involving a coordinated interplay between sensoric, motoric, and cognitive subsystems. To this end, 30 healthy participants (Ø BMI: 22.86 kg/m2; BMI range: 19-30 kg/m2; 23 females) were instructed to collect one of two concurrently presented objects (food vs. office tools) by manual movement in virtual reality (VR) and on a touchscreen. Parallel to the task in VR, regional brain activity was measured by functional near-infrared spectroscopy (fNIRS). In the VR and on the touchscreen, stimulus recognition and selection were faster for food than for office tools. Yet, food was collected more slowly than office tools when measured in VR. On the background of increased brain activity in the right dorsolateral prefrontal cortex (dlPFC) during food trials, this suggests more behavioural control activity during handling foods. In sum, this study emphasizes the role of the right dlPFC in faster recognition and selection of food as part of a food-valuation network, more controlled handling of food in the VR which highlights the relevance of medium for modelling food-specific embodied cognitions.

Meta-analysis of the effects of transcranial direct current stimulation on inhibitory control.

BACKGROUND: Inhibitory control refers to a central cognitive capacity involved in the interruption and correction of actions. Dysfunctions in these cognitive control processes have been identified as major maintaining mechanisms in a range of mental disorders such as ADHD, binge eating disorder, obesity, and addiction. Improving inhibitory control by transcranial direct current stimulation (tDCS) could ameliorate symptoms in a broad range of mental disorders. OBJECTIVE: The primary aim of this pre-registered meta-analysis was to investigate whether inhibitory control can be improved by tDCS in healthy and clinical samples. Additionally, several moderator variables were investigated. METHODS: A comprehensive literature search was performed on PubMed/MEDLINE database, Web of Science, and Scopus. To achieve a homogenous sample, only studies that assessed inhibitory control in the go-/no-go (GNG) or stop-signal task (SST) were included, yielding a total of 75 effect sizes from 45 studies. RESULTS: Results of the meta-analysis indicate a small but significant overall effect of tDCS on inhibitory control (g = 0.21) which was moderated by target and return electrode placement as well as by the task. The small effect size was further reduced after correction for publication bias. CONCLUSION: Based on the studies included, our meta-analytic approach substantiates previously observed differences between brain regions, i.e., involvement of the right inferior frontal gyrus (rIFG) vs. the right dorsolateral prefrontal cortex (rDLPFC) in inhibitory control. Results indicate a small moderating effect of tDCS on inhibitory control in single-session studies and highlight the relevance of technical and behavioral parameters.