Increased anterior cingulate cortex response precedes behavioural adaptation in anorexia nervosa

Altered learning from positive feedback in adolescents with anorexia nervosa

OBJECTIVE

Anorexia nervosa (AN) is characterized by severe restriction of calorie intake, which persists despite serious medical and psychological sequelae of starvation. Several prior studies have identified impaired feedback learning among individuals with AN, but whether it reflects a disturbance in learning from positive feedback (i.e., reward), negative feedback (i.e., punishment), or both, and the extent to which this impairment is related to severity and duration of illness, has not been clarified.

METHOD

Participants were female adolescents with AN (n = 76) and healthy teen volunteers (HC; n = 38) between the ages of 12-18 years who completed a probabilistic reinforcement learning task. A Bayesian reinforcement learning model was used to calculate separate learning rates for positive and negative feedback. Exploratory analyses examined associations between feedback learning and duration of illness, eating disorder severity, and self/parent reports of reward and punishment sensitivity.

RESULTS

Adolescents with AN had a significantly lower rate of learning from positive feedback relative to HC. Patients and HC did not differ in learning from negative feedback or on overall task performance measures. Feedback learning parameters were not significantly associated with duration of illness, eating disorder severity, or questionnaire-based reports of reward and punishment sensitivity.

CONCLUSION

Adolescents with AN showed a circumscribed deficit in learning from reward that was not associated with duration of illness or reported sensitivity to reward or punishment. Subsequent longitudinal research should explore whether differences in learning from positive feedback relate to course of illness in youth with AN.

Impaired flexible reward learning in ADHD patients is associated with blunted reinforcement sensitivity and neural signals in ventral striatum and parietal cortex

Reward-based learning and decision-making are prime candidates to understand symptoms of attention deficit hyperactivity disorder (ADHD). However, only limited evidence is available regarding the neurocomputational underpinnings of the alterations seen in ADHD. This concerns flexible behavioral adaption in dynamically changing environments, which is challenging for individuals with ADHD. One previous study points to elevated choice switching in adolescent ADHD, which was accompanied by disrupted learning signals in medial prefrontal cortex. Here, we investigated young adults with ADHD (n = 17) as compared to age- and sex-matched controls (n = 17) using a probabilistic reversal learning experiment during functional magnetic resonance imaging (fMRI). The task requires continuous learning to guide flexible behavioral adaptation to changing reward contingencies. To disentangle the neurocomputational underpinnings of the behavioral data, we used reinforcement learning (RL) models, which informed the analysis of fMRI data. ADHD patients performed worse than controls particularly in trials before reversals, i.e., when reward contingencies were stable. This pattern resulted from 'noisy' choice switching regardless of previous feedback. RL modelling showed decreased reinforcement sensitivity and enhanced learning rates for negative feedback in ADHD patients. At the neural level, this was reflected in a diminished representation of choice probability in the left posterior parietal cortex in ADHD. Moreover, modelling showed a marginal reduction of learning about the unchosen option, which was paralleled by a marginal reduction in learning signals incorporating the unchosen option in the left ventral striatum. Taken together, we show that impaired flexible behavior in ADHD is due to excessive choice switching ('hyper-flexibility'), which can be detrimental or beneficial depending on the learning environment. Computationally, this resulted from blunted sensitivity to reinforcement of which we detected neural correlates in the attention-control network, specifically in the parietal cortex. These neurocomputational findings remain preliminary due to the relatively small sample size.

Neural effects of deep brain stimulation on reward and loss anticipation and food viewing in anorexia nervosa: a pilot study

BACKGROUND

Anorexia nervosa (AN) is a severe and life-threatening psychiatric disorder. Initial studies on deep brain stimulation (DBS) in severe, treatment-refractory AN have shown clinical effects. However, the working mechanisms of DBS in AN remain largely unknown. Here, we used a task-based functional MRI approach to understand the pathophysiology of AN.

METHODS

We performed functional MRI on four AN patients that participated in a pilot study on the efficacy, safety, and functional effects of DBS targeted at the ventral limb of the capsula interna (vALIC). The patients and six gender-matched healthy controls (HC) were investigated at three different time points. We used an adapted version of the monetary incentive delay task to probe generic reward processing in patients and controls, and a food-specific task in patients only.

RESULTS

At baseline, no significant differences for reward anticipation were found between AN and HC. Significant group (AN and HC) by time (pre- and post-DBS) interactions were found in the right precuneus, right putamen, right ventral and medial orbitofrontal cortex (mOFC). No significant interactions were found in the food viewing task, neither between the conditions high-calorie and low-calorie food images nor between the different time points. This could possibly be due to the small sample size and the lack of a control group.

CONCLUSION

The results showed a difference in the response of reward-related brain areas post-DBS. This supports the hypotheses that the reward circuitry is involved in the pathogenesis of AN and that DBS affects responsivity of reward-related brain areas. Trial registration Registered in the Netherlands Trial Register ( https://www.trialregister.nl/trial/3322 ): NL3322 (NTR3469).

Can neuroimaging measures differentiate the disease course of anorexia nervosa? A systematic review

Anorexia nervosa (AN) entails many uncertainties regarding the clinical outcome, due to large heterogeneity in the disease course. AN is associated with global decrease in brain volumes and altered brain functioning during acute illness. However, it is unclear whether structural and functional brain alterations can predict clinical outcome. We aimed to systematically review the predictive value of volumetric and functional brain outcome measures of structural and functional brain magnetic resonance imaging (MRI) on the disease course of AN. Four databases (Embase, Medline, Psycinfo, and Cochrane Central Register) were systematically searched. A total of 15 studies (structural MRI: n = 6, functional MRI: n = 9) were reviewed. In total 464 unique AN patients, and 328 controls were included. Follow-up time ranged between 1 and 43 months. Structural neuroimaging studies showed that lower brain volumes of the cerebellum, subcortical grey matter, and cortical white matter at admission predicted a worse clinical outcome. A smaller increase of the anterior cingulate cortex volume in the early phase of the disease predicted a worse clinical outcome. Lower overall gyrification, and a higher clustering coefficient predicted a worse clinical outcome. Functional MRI studies showed that frontal, parietal and temporal activity during task-based algorithms predicted follow-up body mass index, although results were bidirectional possibly due to the large heterogeneity in methodological approaches. Neuroimaging measures may predict the clinical outcome of AN. However, there is a lack of replication studies. Future studies are needed to validate the prognostic utility of neuroimaging measures in AN patients, and should harmonize demographic, clinical and neuroimaging features in order to enhance comparability.

Neural activation of regions involved in food reward and cognitive control in young females with anorexia nervosa and atypical anorexia nervosa versus healthy controls

Anorexia nervosa (AN) and atypical AN (AtypAN) are complex neurobiological illnesses that typically onset in adolescence with an often treatment-refractory and chronic illness trajectory. Aberrant eating behaviors in this population have been linked to abnormalities in food reward and cognitive control, but prior studies have not examined respective contributions of clinical characteristics and metabolic state. Research is needed to identify specific disruptions and inform novel intervention targets to improve outcomes. Fifty-nine females with AN (n = 34) or AtypAN (n = 25), ages 10-22 years, all ≤90% expected body weight, and 34 age-matched healthy controls (HC) completed a well-established neuroimaging food cue paradigm fasting and after a standardized meal, and we used ANCOVA models to investigate main and interaction effects of Group and Appetitive State on blood oxygenation level-dependent (BOLD) activation for the contrast of exposure to high-calorie food images minus objects. We found main effects of Group with greater BOLD activation in the dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (DLPFC), hippocampus, caudate, and putamen for AN/AtypAN versus HC groups, and in the three-group model including AN, AtypAN, and HC (sub-)groups, where differences were primarily driven by greater activation in the AtypAN subgroup versus HC group. We found a main effect of Appetitive State with increased premeal BOLD activation in the hypothalamus, amygdala, nucleus accumbens, and caudate for models that included AN/AtypAN and HC groups, and in BOLD activation in the nucleus accumbens for the model that included AN, AtypAN, and HC (sub-)groups. There were no interaction effects of Group with Appetitive State for any of the models. Our findings demonstrate robust feeding-state independent group effects reflecting greater neural activation of specific regions typically associated with reward and cognitive control processing across AN and AtypAN relative to healthy individuals in this food cue paradigm. Differential activation of specific brain regions in response to the passive viewing of high-calorie food images may underlie restrictive eating behavior in this clinical population.

The neural correlates of socio-cognitive factors and eating disorders in young people: A systematic review

BACKGROUND

Although the primary aetiology of Eating Disorders (ED) remains unknown, research suggests a complex interplay of biological, psychological, and cultural/environmental factors. This paper aims to systematically review the literature on neuroimaging studies that measure socio-cognitive factors, in the context of body dissatisfaction and EDs in young people. Specifically, our aim was to identify patterns in the findings linked to social media-type behaviours.

METHODS

The review was conducted in accordance with PRISMA guidelines using PubMed, Scopus, and Web of Science databases. 799 papers were identified in the database search and 38 studies were selected based on exclusion and inclusion criteria. Selected studies were assessed using the National Institute of Health study quality assessment tool.

RESULTS

Findings point to state-related impairments in inhibitory control and salient emotional processing. Anorexia Nervosa(AN) showed impaired set-shifting abilities, working memory and decision making, while altered activation in attention networks and associated difficulties with conflict resolution were seen for Bulimia Nervosa(BN) and Other Specified Feeding and Eating Disorders(OSFED). AN and BN also demonstrated altered sensitivity to food-related stimuli in striatal regions, suggesting aberrant top-down emotional-cognitive control. ED participants also show deficits in body representation, impaired control over social behaviours and altered integration of visual and body perception.

DISCUSSION

These findings support the notion that socio-cognitive dysfunctions in ED are underpinned by a distributed network of structural and functional brain changes which influence the way young people with ED interact with and respond to social media, and ultimately places at them at increased risk for body image disturbances. This Review was registered with the PROSPERO International Register of Systematic Reviews, Registration number CRD42021270696.

Altered Reinforcement Learning from Reward and Punishment in Anorexia Nervosa: Evidence from Computational Modeling

OBJECTIVES

Anorexia nervosa (AN) is associated with altered sensitivity to reward and punishment. Few studies have investigated whether this results in aberrant learning. The ability to learn from rewarding and aversive experiences is essential for flexibly adapting to changing environments, yet individuals with AN tend to demonstrate cognitive inflexibility, difficulty set-shifting and altered decision-making. Deficient reinforcement learning may contribute to repeated engagement in maladaptive behavior.

METHODS

This study investigated learning in AN using a probabilistic associative learning task that separated learning of stimuli via reward from learning via punishment. Forty-two individuals with Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 restricting-type AN were compared to 38 healthy controls (HCs). We applied computational models of reinforcement learning to assess group differences in learning, thought to be driven by violations in expectations, or prediction errors (PEs). Linear regression analyses examined whether learning parameters predicted BMI at discharge.

RESULTS

AN had lower learning rates than HC following both positive and negative PE (p < .02), and were less likely to exploit what they had learned. Negative PE on punishment trials predicted lower discharge BMI (p < .001), suggesting individuals with more negative expectancies about avoiding punishment had the poorest outcome.

CONCLUSIONS

This is the first study to show lower rates of learning in AN following both positive and negative outcomes, with worse punishment learning predicting less weight gain. An inability to modify expectations about avoiding punishment might explain persistence of restricted eating despite negative consequences, and suggests that treatments that modify negative expectancy might be effective in reducing food avoidance in AN.

Neural Correlates of Executive Functioning in Anorexia Nervosa and Obsessive-Compulsive Disorder

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are commonly reported to co-occur and present with overlapping symptomatology. Executive functioning difficulties have been implicated in both mental health conditions. However, studies directly comparing these functions in AN and OCD are extremely limited. This review provides a synthesis of behavioral and neuroimaging research examining executive functioning in AN and OCD to bridge this gap in knowledge. We outline the similarities and differences in behavioral and neuroimaging findings between AN and OCD, focusing on set shifting, working memory, response inhibition, and response monitoring. This review aims to facilitate understanding of transdiagnostic correlates of executive functioning and highlights important considerations for future research. We also discuss the importance of examining both behavioral and neural markers when studying transdiagnostic correlates of executive functions.

A meta-analytic investigation of grey matter differences in anorexia nervosa and autism spectrum disorder

Recent research reports Anorexia Nervosa (AN) to be highly dependent upon neurobiological function. Some behaviours, particularly concerning food selectivity are found in populations with both Autism Spectrum Disorder (ASD) and AN, and there is a proportionally elevated number of anorexic patients exhibiting symptoms of ASD. We performed a systematic review of structural MRI literature with the aim of identifying common structural neural correlates common to both AN and ASD. Across 46 ASD publications, a meta‐analysis of volumetric differences between ASD and healthy controls revealed no consistently affected brain regions. Meta‐analysis of 23 AN publications revealed increased volume within the orbitofrontal cortex and medial temporal lobe, and adult‐only AN literature revealed differences within the genu of the anterior cingulate cortex. The changes are consistent with alterations in flexible reward‐related learning and episodic memory reported in neuropsychological studies. There was no structural overlap between ASD and AN. Findings suggest no consistent neuroanatomical abnormality associated with ASD, and evidence is lacking to suggest that reported behavioural similarities between those with AN and ASD are due to neuroanatomical structural similarities.

Findings related to neuroanatomical structure in AN/ASD demonstrate overlap and require revisiting.

Meta‐analytic findings show structural increase/decrease versus healthy controls (LPFC/MTL/OFC) in AN, but no clusters found in ASD.

The neuroanatomy associated with ASD is inconsistent, but findings in AN reflect condition‐related impairment in executive function and sociocognitive behaviours.

The BDNF Val66Met Polymorphism Does Not Increase Susceptibility to Activity-Based Anorexia in Rats

Simple Summary

Genetic animal models are a valuable tool for understanding how human pathologies develop. The type of animal model chosen is important for uncovering effects specific to certain behaviours and neurobiological functions. A polymorphism in the brain-derived neurotrophic factor (BDNF) has been linked with various clinical conditions in human subjects and with mouse models of anorectic behaviour. This study investigated for the first time the role of the BDNF Val66Met allelic substitution in a rat model of anorexia nervosa (AN), known as activity-based anorexia (ABA). Contrary to reports of altered BDNF signaling in patients with AN and increased anorectic behaviour in a mouse model containing the same allelic variation, it showed that 66Met did not alter susceptibility to weight loss or aspects of energy balance, including feeding and exercise in the rat model. It highlights the need to consider species–specific differences when evaluating animal models of human pathologies.

Abstract

Brain-derived neurotrophic factor (BDNF) is abundantly expressed in brain regions involved in both homeostatic and hedonic feeding, and it circulates at reduced levels in patients with anorexia nervosa (AN). A single nucleotide polymorphism in the gene encoding for BDNF (Val66Met) has been associated with worse outcomes in patients with AN, and it is shown to promote anorectic behaviour in a mouse model of caloric restriction paired with social isolation stress. Previous animal models of the Val66Met polymorphism have been in mice because of the greater ease in modification of the mouse genome, however, the most widely-accepted animal model of AN, known as activity-based anorexia (ABA), is most commonly conducted in rats. Here, we examine ABA outcomes in a novel rat model of the BDNF Val66Met allelic variation (Val68Met), and we investigate the role of this polymorphism in feeding, food choice and sucrose preference, and energy expenditure. We demonstrate that the BDNF Val68Met polymorphism does not influence susceptibility to ABA or any aspect of feeding behaviour. The discrepancy between these results and previous reports in mice may relate to species–specific differences in stress reactivity.

Executive function in obesity and anorexia nervosa: Opposite ends of a spectrum of disordered feeding behaviour?

Higher-order executive functions such as decision-making, cognitive flexibility and behavioural control are critical to adaptive success in all aspects of life, including the maintenance of a healthy body weight by regulating food intake. Performance on tasks designed to assess these aspects of cognition is impaired in individuals with obesity and anorexia nervosa (AN); conditions at either end of a spectrum of body weight disturbance. While the conceptualisation of obesity and AN as mirror images of each other makes some sense from a metabolic point of view, whether or not these conditions also reflect opposing states of executive function is less clear. Here, we review evidence from neurocognitive and neuroimaging studies to compare the direction and extent of executive dysfunction in subjects with obesity and AN and how these are underpinned by changes in structure and function of subregions of the prefrontal cortex (PFC). Both conditions of extreme body weight disturbance are associated with impaired decision-making and cognitive inflexibility, however, impulsive behaviour presents in opposing directions; obesity being associated with reduced behavioural control and AN being associated with elevated control over behaviour with respect to food and feeding. Accordingly, the subregions of the PFC that guide inhibitory control and valuation of action outcomes (dorsolateral prefrontal cortex and orbitofrontal cortex) show opposite patterns of activation in subjects with obesity compared to those with AN, whereas the subregions implicated in cognitive and behavioural flexibility (ventromedial prefrontal cortex and anterior cingulate cortex) show alterations in the same direction in both conditions but with differential extent of dysfunction. We synthesise these findings in the context of the utility of animal models of obesity and AN to interrogate the detail of the neurobiological contributions to cognition in patient populations and the utility of such detail to inform future treatment strategies that specifically target executive dysfunction.

Associations of observed preschool performance monitoring with brain functional connectivity in adolescence

Monitoring one's performance helps detect errors and adapt to prevent future mistakes. However, elevated performance monitoring is associated with increased checking behaviors and perfectionism and is characteristic of multiple psychiatric disorders. Understanding how heightened performance monitoring in early childhood relates to subsequent brain connectivity may elucidate mechanistic risk factors that influence brain and psychiatric outcomes. The aim of this study was to examine the association between performance monitoring in preschool-aged children and functional connectivity during adolescence. In the current prospective longitudinal study, we performed seed-based functional connectivity analysis using a dorsal anterior cingulate cortex (dACC) seed to assess brain-behavior relationships between observationally coded performance monitoring in preschool-aged children and adolescent functional connectivity (n = 79). We also utilized enrichment analysis to investigate network-level connectome-wide associations. Seed-based analysis revealed negative correlations between preschool performance monitoring and adolescent fc between dACC and orbitofrontal and dorsolateral prefrontal cortex while a positive correlation was observed between dACC-occipital cortex connectivity. Enrichment analysis revealed a negative correlation between preschool performance monitoring and connectivity between motor (MOT) - cingulo-opercular (CO) and salience (SN) - Reward (REW) and a positive correlation with MOT-DMN, and cerebellum (CB) - motor connectivity. Elevated performance monitoring in early childhood is associated with functional connectivity during adolescence in regions and networks associated with cognitive control, sensorimotor processing and cortico-striatal-thalamic-cortico (CTSC) aberrations. These regions and networks are implicated in psychiatric disorders characterized by elevated performance monitoring. Findings shed light on a mechanistic risk factor in early childhood with long-term associations with neural functioning.

Attenuated neuronal and autonomic responses during error processing in anorexia nervosa

INTRODUCTION

Anorexia nervosa (AN) is a severe psychiatric illness with alarming mortality rates. Nevertheless, despite former and recent research results, the etiology of AN is still poorly understood. Of particular interest is that, despite exaggerated response control and increased perfectionism scores, patients with AN seem not to perform better that those unaffected in tasks that require inhibitory control. One reason might be aberrant processing of errors. The objective of our study was thus to obtain further insight into the pathopsychology of AN. We were particularly interested in neuronal and autonomic responses during error processing and their association with behavior.

METHODS

We analyzed 16 acute patients suffering from restrictive type AN and 21 healthy controls using functional magnetic resonance imaging (fMRI) with simultaneous physiological recordings during a Go/Nogo response inhibition task. Data were corrected for noise due to cardiac and respiratory influence.

RESULTS

Patients and controls had similarly successful response inhibition in Nogo trials. However, in failed Nogo trials, controls had significantly greater skin conductance responses (SCR) than in correct Nogo trials. Patients did not exhibit elevated SCR to errors. Furthermore, we found significantly increased neuronal responses, especially in the amygdala and hippocampus, in controls compared to patients during error trials. We also found significant positive correlations in controls but not in patients between Nogo performance and activation in the salience network core regions after errors.

CONCLUSION

Acute restrictive type AN patients seem to lack neuronal and autonomic responses to errors that might impede a flexible behavior adaption.

Shift Toward Randomness in Brain Networks of Patients With Anorexia Nervosa: The Role of Malnutrition

No study to date investigated structural white matter (WM) connectome characteristics in patients with anorexia nervosa (AN). Previous research in AN found evidence of imbalances in global and regional connectomic brain architecture and highlighted a role of malnutrition in determining structural brain changes. The aim of our study was to explore the characteristics of the WM network architecture in a sample of patients with AN. Thirty-six patients with AN and 36 healthy women underwent magnetic resonance imaging to obtain a high-resolution three-dimensional T1-weighted anatomical image and a diffusion tensor imaging scan. Probabilistic tractography data were extracted and analyzed in their network properties through graph theory tools. In comparison to healthy women, patients with AN showed lower global network segregation (normalized clustering: p = 0.029), an imbalance between global network integration and segregation (i.e., lower small-worldness: p = 0.031), and the loss of some of the most integrative and influential hubs. Both clustering and small-worldness correlated with the lowest lifetime body mass index. A significant relationship was found between the average regional loss of cortical volume and changes in network properties of brain nodes: the more the difference in the cortical volume of brain areas, the more the increase in the centrality of corresponding nodes in the whole brain, and the decrease in clustering and efficiency of the nodes of parietal cortex. Our findings showed an unbalanced connectome wiring in AN patients, which seems to be influenced by malnutrition and loss of cortical volume. The role of this rearrangement in the maintenance and prognosis of AN and its reversibility with clinical improvement needs to be established by future studies.

Joint Hypermobility and Clinical Correlates in a Group of Patients With Eating Disorders

Background: The ability to move joints beyond the normal range of motion is called Joint Hypermobility (JHM). JHM has been associated with a plethora of physical problems and is a frequent sign of hereditary disorders of connective tissue. Neuropsychiatric conditions such as eating disorders (ED) have also been related to JHM. However, little is known about the clinical profile of people with ED and JHM. The aim of this study was to explore JHM in patients with ED and to compare the clinical characteristics of hypermobile ED patients with non-hypermobile ED patients. Method: Fifty-three outpatients diagnosed with ED were assessed using the Beighton score for JHM, the Eating Disorders Inventory 2, the Eating Disorder Examination, and the Detail and Flexibility Questionnaire. Information relating to patients' psychiatric and somatic comorbidities/symptoms was also collected. Results: Using the traditional Beighton score's cutoff of ≥4, 41.5% of the sample presented with JHM. Our results indicate that compared with non-hypermobile ED patients, those with JHM are significantly younger, suffer at a greater extent from joint pain and easy bruising, have a shorter duration of the ED, and have lower scores for cognitive rigidity. In addition, for those with anorexia nervosa, the restricting subtype represents a significantly lower proportion of hypermobile ED patients compared to non-hypermobile ED patients. Multivariate analyses showed that cognitive rigidity, age, and duration of the ED could predict the JHM status in this sample. Conclusion: These results suggest that JHM is frequent in patients with ED and is accompanied by signs of tissue fragility. Patients with ED and JHM seem to present a specific profile characterized by less cognitive rigidity and restricting behavior in the case of anorexia nervosa. Further research is needed in order to confirm these results.

Cognitive flexibility in acute anorexia nervosa and after recovery: A systematic review

Difficulties in cognitive flexibility-the ability to adapt effectively to changes in the environment and/or changing task demands-have been reported in anorexia nervosa (AN). However, findings are inconsistent across studies and it remains unclear which specific aspects of cognitive flexibility patients with AN may struggle with. This systematic review aimed to synthesise existing research on cognitive flexibility in AN and clarify differences between patients with acute AN, patients who are weight-restored and patients who are fully recovered from AN. Electronic databases were searched through to January 2020. 3,310 papers were screened and 70 papers were included in the final review. Although adults with acute AN performed worse in perceptual flexibility tasks and self-report measures compared to HCs, they did not exhibit deficits across all domains of cognitive flexibility. Adolescents with acute AN did not differ to HCs in performance on neurocognitive tasks despite self-reporting poorer cognitive flexibility. Overall, significant differences in cognitive flexibility between acute and recovered participants was not evident, though, the findings are limited by a modest number of studies. Recovered participants performed poorer than HCs in some neurocognitive measures, however, results were inconsistent across studies. These results have implications for the assessment of cognitive flexibility in AN and targeted treatment approaches.

Semantic and attentional networks in bilingual processing: fMRI connectivity signatures of translation directionality

Comparisons between backward and forward translation (BT, FT) have long illuminated the organization of bilingual memory, with neuroscientific evidence indicating that FT would involve greater linguistic and attentional demands. However, no study has directly assessed the functional interaction between relevant mechanisms. Against this background, we conducted the first fMRI investigation of functional connectivity (FC) differences between BT and FT. In addition to yielding lower behavioral outcomes, FT was characterized by increased FC between a core semantic hub (the left anterior temporal lobe, ATL) and key nodes of attentional and vigilance networks (left inferior frontal, left orbitofrontal, and bilateral parietal clusters). Instead, distinct FC patterns for BT emerged only between the left ATL and the right thalamus, a region implicated in automatic relaying of sensory information to cortical regions. Therefore, FT seems to involve enhanced coupling between semantic and attentional mechanisms, suggesting that asymmetries in cross-language processing reflect dynamic interactions between linguistic and domain-general systems.

Moving towards specificity: A systematic review of cue features associated with reward and punishment in anorexia nervosa

Models of anorexia nervosa (AN) posit that symptoms are maintained through deficient reward and enhanced punishment processing. However, theoretical and empirical inconsistencies highlight the need for a more nuanced conceptualization of this literature. Our goal was to comprehensively review the research on reward and punishment responding in AN from a cue-specific lens to determine which stimuli evoke or discourage reward and punishment responses in this population, and, ultimately, what properties these rewarding and punishing cues might share. A systematic review interrogating reward and punishment responses to specific cues yielded articles (n = 92) that examined responses to disorder relevant (e.g., food) and irrelevant (e.g., money) stimuli across self-report, behavioral, and biological indices. Overall, in most studies individuals with AN exhibited aversive responses to cues signaling higher body weights, social contexts, and monetary losses, and appetitive responses to cues for weight loss behaviors and thinness. Findings were more mixed on responses to palatable food and monetary gains. Results highlight that reward and punishment responding in AN are context specific and may be affected by varied stimulus qualities (e.g., predictability, controllability, delay, effort). Increasing specificity in future research on reward and punishment mechanisms in AN will better inform development of precisely-targeted interventions.

Intact value-based decision-making during intertemporal choice in women with remitted anorexia nervosa? An fMRI study

BACKGROUND

Extreme restrictive food choice in anorexia nervosa is thought to reflect excessive self-control and/or abnormal reward sensitivity. Studies using intertemporal choice paradigms have suggested an increased capacity to delay reward in anorexia nervosa, and this may explain an unusual ability to resist immediate temptation and override hunger in the long-term pursuit of thinness. It remains unclear, however, whether altered delay discounting in anorexia nervosa constitutes a state effect of acute illness or a trait marker observable after recovery.

METHODS

We repeated the analysis from our previous fMRI investigation of intertemporal choice in acutely underweight patients with anorexia nervosa in a sample of weight-recovered women with anorexia nervosa (n = 36) and age-matched healthy controls (n = 36) who participated in the same study protocol. Follow-up analyses explored functional connectivity separately in both the weight-recovered/healthy controls sample and the acute/healthy controls sample.

RESULTS

In contrast to our previous findings in acutely underweight patients with anorexia nervosa, we found no differences between weight-recovered patients with anorexia nervosa and healthy controls at either behavioural or neural levels. New analysis of data from the acute/healthy controls sample sample revealed increased coupling between dorsal anterior cingulate cortex and posterior brain regions as a function of decision difficulty, supporting the hypothesis of altered neural efficiency in the underweight state.

LIMITATIONS

This was a cross-sectional study, and the results may be task-specific.

CONCLUSION

Although our results underlined previous demonstrations of divergent temporal reward discounting in acutely underweight patients with anorexia nervosa, we found no evidence of alteration in patients with weight-recovered anorexia nervosa. Together, these findings suggest that impaired valuebased decision-making may not constitute a defining trait variable or “scar” of the disorder.

The tenacious brain: How the anterior mid-cingulate contributes to achieving goals

Tenacity-persistence in the face of challenge-has received increasing attention, particularly because it contributes to better academic achievement, career opportunities and health outcomes. We review evidence from non-human primate neuroanatomy and structural and functional neuroimaging in humans suggesting that the anterior mid cingulate cortex (aMCC) is an important network hub in the brain that performs the cost/benefit computations necessary for tenacity. Specifically, we propose that its position as a structural and functional hub allows the aMCC to integrate signals from diverse brain systems to predict energy requirements that are needed for attention allocation, encoding of new information, and physical movement, all in the service of goal attainment. We review and integrate research findings from studies of attention, reward, memory, affect, multimodal sensory integration, and motor control to support this hypothesis. We close by discussing the implications of our framework for educational achievement, exercise and eating disorders, successful aging, and neuropsychiatric disorders such as depression and dementia.

Functional Connectivity Patterns and the Role of 5-HTTLPR Polymorphism on Network Architecture in Female Patients With Anorexia Nervosa

Introduction

Recent neuroimaging studies suggest that anorexia nervosa (AN) symptoms emerge from failures in the relationships between spatially distributed networks that support different cognitive, emotional, and somatosensory functions. The 5-HTTLPR genotype has been shown to modulate all these abilities in AN, as well as the connectivity patterns between brain regions that support their functioning. This study aims at exploring the presence of any difference in functional connectome properties between AN patients and healthy controls (HC) by means of graph theory tools. The effect of 5-HTTLPR genotype on regional and global network characteristics in AN and HC was also explored.

Methods

A sample of 74 subjects (38 HC, 36 AN) underwent a resting state functional magnetic resonance imaging and was genotyped for 5-HTTLPR polymorphism. Comparisons of network properties were made between the AN and HC groups and, within each group, between 5-HTTLPR carriers of low-functioning alleles and carriers of the long–long genotype.

Results

Patients with AN displayed lower network clustering than HC (p = 0.04 at Mann–Whitney U test). Based on both degree and betweenness, a different distribution of network hubs emerged in the two groups. In particular, the anterior part of the anterior cingulate cortex was a hub only in the patient group. A correlation emerged between differences in brain volumes between patients and HC and differences in degree values of basal ganglia, nodes in the insula, and those in the parietal cortex. Carriers of the short allele of the 5-HTTLPR polymorphism were characterized by lower small-world properties (p = 0.027) and modularity (p = 0.031) in the patient group, and a trend toward higher modularity (p = 0.033) and small-world values (p = 0.123) in the HC group.

Discussion

Patients with AN showed differences in hubs distribution, providing evidence of the presence of a different functional architectural backbone in this group. Since some correlation emerged between different degree values of nodes and differences in volumes, further longitudinal studies are warranted to better understand the role of malnutrition on brain network architecture. The opposite effects of 5-HTTLPR polymorphism on global network characteristics in the two groups suggest an interaction of the short allele and malnutrition in modulating brain network properties.

The Neurobiology of Eating Disorders

Eating disorders are severe psychiatric illnesses with a typical age of onset in adolescence. Brain research in youth and young adults may help us identify specific neurobiology that contributes to onset and maintenance of those disorders. This article provides a state-of-the-art review of our current understanding of the neurobiology of anorexia nervosa and bulimia nervosa. This includes brain structure and function studies to understand food restriction, binge-eating or purging behaviors, cognitive and emotional factors, as well as interoception. Binge-eating disorder and avoidant restrictive food intake disorder are also discussed, but the literature is still very small.

Neural correlates of taste reward value across eating disorders

Individuals with eating disorders (ED) make extreme food choices, raising the possibility of altered food-value computation. We utilized an associative taste reward learning paradigm to test whether value signaling differs between participants with EDs vs. healthy controls (HC). We followed up on previous work examining prediction error (PE) signaling, which is a brain response to violation of a learned reward contingency. Expected value (EV) signal is a trial-by-trial assessment of reward significance accounting for error signaling, reward-likelihood, and learning rate. Adult female participants (N = 111) performed a temporal difference (TD) fMRI taste task, which is a specific type of associative reward learning paradigm, to determine EV signal: Anorexia Nervosa-ill (N = 28), Anorexia Nervosa-recovered (N = 20), Bulimia Nervosa (BN) (N = 20), and HC (N= 43). Anatomical region-of-interest (ROI) analyses were performed utilizing EV regressors derived via algorithm, with ROIs based on prior EV analyses: orbitofrontal cortex, anterior cingulate (ACC), amygdala, and striatum. EV signal was elevated in the bilateral ACC in AN-ill vs. HC and BN. Intolerance of uncertainty negatively correlated with EV in AN-ill. BMI and EV were negatively-correlated across groups. Altered ACC EV computation in response to food stimuli could contribute to food restriction in AN-ill.

Neural Correlates of Failed Inhibitory Control as an Early Marker of Disordered Eating in Adolescents

BACKGROUND

Binge eating and other forms of disordered eating behavior (DEB) are associated with failed inhibitory control. This study investigated the neural correlates of failed inhibitory control as a potential biomarker for DEB.

METHODS

The study used prospective longitudinal data from the European IMAGEN study adolescent cohort. Participants completed baseline assessments (questionnaires and a brain scan [functional magnetic resonance imaging]) at 14 years of age and a follow-up assessment (questionnaires) at 16 years of age. Self-reported binge eating and/or purging were used to indicate presence of DEB. Neural correlates of failed inhibition were assessed using the stop signal task. Participants were categorized as healthy control subjects (reported no DEB at both time points), maintainers (reported DEB at both time points), recoverers (reported DEB at baseline only), and developers (reported DEB at follow-up only). Forty-three individuals per group with complete scanning data were matched on gender, age, puberty, and intelligence (N = 172).

RESULTS

At baseline, despite similar task performance, incorrectly responding to stop signals (failed inhibitory control) was associated with greater recruitment of the medial prefrontal cortex and anterior cingulate cortex in the developers compared with healthy control subjects and recoverers.

CONCLUSIONS

Greater recruitment of the medial prefrontal and anterior cingulate regions during failed inhibition accords with abnormal evaluation of errors contributing to DEB development. As this precedes symptom onset and is evident despite normal task performance, neural responses during failed inhibition may be a useful biomarker of vulnerability for DEB. This study highlights the potential value of prospective neuroimaging studies for identifying markers of illness before the emergence of behavior changes.

Recent advances in understanding anorexia nervosa

Anorexia nervosa is a complex psychiatric illness associated with food restriction and high mortality. Recent brain research in adolescents and adults with anorexia nervosa has used larger sample sizes compared with earlier studies and tasks that test specific brain circuits. Those studies have produced more robust results and advanced our knowledge of underlying biological mechanisms that may contribute to the development and maintenance of anorexia nervosa. It is now recognized that malnutrition and dehydration lead to dynamic changes in brain structure across the brain, which normalize with weight restoration. Some structural alterations could be trait factors but require replication. Functional brain imaging and behavioral studies have implicated learning-related brain circuits that may contribute to food restriction in anorexia nervosa. Most notably, those circuits involve striatal, insular, and frontal cortical regions that drive learning from reward and punishment, as well as habit learning. Disturbances in those circuits may lead to a vicious cycle that hampers recovery. Other studies have started to explore the neurobiology of interoception or social interaction and whether the connectivity between brain regions is altered in anorexia nervosa. All together, these studies build upon earlier research that indicated neurotransmitter abnormalities in anorexia nervosa and help us develop models of a distinct neurobiology that underlies anorexia nervosa.

Body image disturbances, fear and associations with the amygdala in anorexia nervosa

Background

Anorexia nervosa (AN) is a severe illness with a high mortality rate which mainly affects young women. Studies found a localized volume loss of the amygdala in patients with AN, a brain region responsible for affective responses. Patients with AN were found to have body image distortions, and suffer from the comorbid disorders depression, anxiety disorder, and obsession. Therefore, the purpose of this study was to analyze a possible connection between comorbidities, body image disturbances, and the volume of the amygdala in patients with AN.

Methods

In this study 21 females suffering from restrictive-type AN and 21 age-matched normal controls (NC) were tested. Demographic data as well as body image perceptions and comorbidities were assessed. Volumes of cortical structures were measured with a magnetic resonance (MR) scanner. Analyses of variance were conducted to analyze group differences, and correlations between the volume of the amygdala and comorbidities and body image perceptions were calculated.

Results

The results showed a significantly lower grey matter volume in the amygdala in AN patients compared to the NC. Persons with AN showed more body image disturbances and suffered more often from depression, and phobias than NC. The volume of the amygdala showed a non-significant mid-level association with phobia and with uncertainty concerning their body in AN patients.

Conclusion

The study indicates that phobic anxiety and body image in patients with AN could be related to the volume of the amygdala. The results contribute to a better understanding of the pathophysiology of the disease.

Neurobiology of social reward valuation in adults with a history of anorexia nervosa

Objective

Anorexia nervosa (AN) is a disorder characterized by atypical patterns of reward valuation (e.g. positive valuation of hunger). Atypical reward processing may extend into social domains. If so, such findings would be of prognostic significance as impaired social functioning predicts worse outcome. We explore neural circuits implicated in social reward processing in individuals with a history of AN who are weight-restored relative to controls and examine the effects of illness course on the experience of social value.

Method

20 weight-restored individuals with a history of AN (AN-WR) and 24 healthy control (HC) participants were assessed using fMRI tasks that tapped social reward: smiling faces and full human figures that varied in attractiveness and weight.

Results

AN-WR differed from HC in attractiveness ratings by weight (negatively correlated in AN-WR). While there were no significant differences when viewing smiling faces, viewing full figures resulted in decreased activation in regions implicated in reward valuation (the right caudate) for AN-WR and this region was negatively correlated with a sustained course of the disorder. Exploratory whole brain analyses revealed reduced activation in regions associated with social reward, self-referential processing, and cognitive reappraisal (e.g., medial prefrontal cortex, striatum, and nucleus accumbens) with sustained disorder course.

Discussion

The rewarding value of full body images decreases with a sustained disorder course. This may reflect an extension of atypical reward processing documented in AN-WR, perhaps as a function of starvation dampening visceral motivational signals; the deployment of cognitive strategies that lessen the experience of reward; and/or the nature of the stimuli themselves as provocative of eating disorder symptoms (e.g., thin bodies). These findings did not extend to smiling face stimuli. Advances in technology (e.g., virtual avatars, text messaging) may provide novel means to build relationships, including therapeutic relationships, to support improved social connections without threats to symptom provocation.

Evidence of prefrontal hyperactivation to food-cue reversal learning in adolescents with anorexia nervosa

Food avoidance in anorexia nervosa (AN) has been hypothesized to occur as a result of deficits in reversal learning and altered neuronal processing of food-cue relationships. Extant findings suggest that those with AN may rely on heightened recruitment of prefrontal regions during initial formation of food-cue learning and difficulty extinguishing these relationships may result from elevated insula activity. We tested this hypothesis by comparing behavioral and neuronal responses to food-cue acquisition and reversal between adolescents with AN and healthy controls. Compared to controls, acquisition of a food-cue association and its reversal were associated with elevated prefrontal activation in adolescents with AN. There were no significant differences between groups in insula activation and no behavioral differences in the ability to acquire or reverse the food-cue association. The results suggest that adolescents with AN recruit prefrontal regulatory networks to acquire and alter expectancies to food. This pattern of top-down prefrontal control suggests that clinical interventions that target changes in food-cue relationships and rely on cognitive control may be less effective. Interventions that alter behavior without reliance on this top-down control may have advantages with this population.

Altered Medial Frontal Feedback Learning Signals in Anorexia Nervosa

BACKGROUND

In their relentless pursuit of thinness, individuals with anorexia nervosa (AN) engage in maladaptive behaviors (restrictive food choices and overexercising) that may originate in altered decision making and learning.

METHODS

In this functional magnetic resonance imaging study, we employed computational modeling to elucidate the neural correlates of feedback learning and value-based decision making in 36 female patients with AN and 36 age-matched healthy volunteers (12-24 years). Participants performed a decision task that required adaptation to changing reward contingencies. Data were analyzed within a hierarchical Gaussian filter model that captures interindividual variability in learning under uncertainty.

RESULTS

Behaviorally, patients displayed an increased learning rate specifically after punishments. At the neural level, hemodynamic correlates for the learning rate, expected value, and prediction error did not differ between the groups. However, activity in the posterior medial frontal cortex was elevated in AN following punishment.

CONCLUSIONS

Our findings suggest that the neural underpinning of feedback learning is selectively altered for punishment in AN.

Neural Network Alterations Across Eating Disorders: A Narrative Review of fMRI Studies

BACKGROUND

Functional magnetic resonance imaging (fMRI) has provided insight on how neural abnormalities are related to the symptomatology of the eating disorders (EDs): anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). More specifically, an increasingly growing number of brain imaging studies has shed light on how functionally connected brain networks contribute not only to disturbed eating behavior, but also to transdiagnostic alterations in body/interoceptive perception, reward processing and executive functioning.

METHODS

This narrative review aims to summarize recent advances in fMRI studies of patients with EDs by highlighting studies investigating network alterations that are shared across EDs.

RESULTS AND CONCLUSION

Findings on reward processing in both AN and BN patients point to the presence of altered sensitivity to salient food stimuli in striatal regions and to the possibility of hypothalamic inputs being overridden by top-down emotional-cognitive control regions. Additionally, innovative new lines of research suggest that increased activations in fronto-striatal circuits are strongly associated with the maintenance of restrictive eating habits in AN patients. Although significantly fewer studies have been carried out in patients with BN and BED, aberrant neural responses to both food cues and anticipated food receipt appear to occur in these populations. These altered responses, coupled with diminished recruitment of prefrontal cognitive control circuitry, are believed to contribute to the binge eating of palatable foods. Results from functional network connectivity studies are diverse, but findings tend to converge on indicating disrupted resting-state connectivity in executive networks, the default-mode network and the salience network across EDs.

Using the research domain criteria (RDoC) to conceptualize impulsivity and compulsivity in relation to addiction

Nomenclature for mental disorder was updated in 2013 with the publication of the fifth edition of the Diagnostic and Statistical Manual (DSM-5). In DSM-5, substance use disorders are framed as more dimensional. First, the distinction between abuse and dependence is replaced by substance use. Second, the addictions section now covers both substances and behavioral addictions. This contemporary move toward dimensionality and transdiagnosis in the addictions and other disorders embrace accumulating cognitive-affective neurobiological evidence that is reflected in the United States' National Institutes of Health Research Domain Criteria (NIH RDoC). The RDoC calls for the further development of transdiagnostic approaches to psychopathy and includes five domains to improve research. Additionally, the RDoC suggests that these domains can be measured in terms of specific units of analysis. In line with these suggestions, recent publications have stimulated updated neurobiological conceptualizations of two transdiagnostic concepts, namely impulsivity and compulsivity and their interactions that are applicable to addictive disorders. However, there has not yet been a review to examine the constructs of impulsivity and compulsivity in relation to addiction in light of the research-oriented RDoC. By doing so it may become clearer as to whether impulsivity and compulsivity function antagonistically, complementarily or in some other way at the behavioral, cognitive, and neural level and how this relationship underpins addiction. Thus, here we consider research into impulsivity and compulsivity in light of the transdiagnostic RDoC to help better understand these concepts and their application to evidence-based clinical intervention for addiction.

Neural correlates of altered feedback learning in women recovered from anorexia nervosa

Anorexia nervosa (AN) is associated with exaggerated self-control and altered reward-based decision making, but the underlying neural mechanisms are poorly understood. Consistent with the notion of excessive cognitive control, we recently found increased dorsal anterior cingulate cortex (dACC) activation in acutely ill patients (acAN) on lose-shift trials in a probabilistic reversal learning (PRL) task. However, undernutrition may modulate brain function. In attempt to disentangle trait from state factors, the current fMRI study investigated cognitive control in recovered patients (recAN). Thirty-one recAN and 31 healthy controls (HC) completed a PRL task during fMRI. Based on previous findings, we focused on hemodynamic responses during lose-shift behaviour and conducted supplementary functional connectivity analysis. RecAN showed elevated lose-shift behaviour relative to HC. On the neural level, recAN showed normal dACC responses, but increased activation in fronto-parietal control regions. A trend for increased coupling between frontal and parietal regions of interest was also evident in recAN. The current findings in recAN differ from those in our previous study in acAN. While aberrant dACC response to negative feedback may be a correlate of the underweight state in acAN, impaired behavioural adaptation and elevated activation of cognitive control regions in recAN is suggestive of altered neural efficiency.