Negative mood affects brain processing of visceral sensation

The effect of experimental emotion induction on experimental pain: a systematic review and meta-analysis

ABSTRACT

The idea that emotions can influence pain is generally recognized. However, a synthesis of the numerous individual experimental studies on this subject is lacking. The aim of the present systematic review and meta-analysis was to synthesize the existing evidence on the effect of experimental emotion induction on experimental pain in nonclinical adults. PsycInfo and PubMed were searched up until April 10, 2023, for studies assessing differences in self-reported pain between emotion induction groups and/or control groups or between conditions within group. Risk of bias was assessed for the individual studies. The literature search yielded 78 relevant records of 71 independent studies. When compared with control conditions, the pooled results revealed a statistically significant pain-attenuating effect of positive emotion induction (between-group: Hedges g = -0.48, 95% CI: -0.72; -0.25, K = 9; within-group: g = -0.24, 95% CI: -0.32; -0.15, K = 40), and a statistically significant pain-exacerbating effect of negative emotion induction in within-group analyses but not between-group analyses (between-group: g = -0.29, 95% CI: -0.66; 0.07, K = 10; within-group: g = 0.14, 95% CI: 0.06; 0.23, K = 39). Bayesian meta-analysis provided strong support for an effect of positive emotion induction but weak support for an effect of negative emotion induction. Taken together, the findings indicate a pain-attenuating effect of positive emotion induction, while the findings for negative emotion induction are less clear. The findings are discussed with reference to theoretical work emphasizing the role of motivational systems and distraction for pain. Limitations include considerable heterogeneity across studies limiting the generalizability of the findings.

Where alcohol use disorder meets interoception: A meta-analytic view on structural and functional neuroimaging data

Alcohol use disorder (AUD) has been associated with changes in the processing of internal body signals, known as interoception. Changes in brain structure, particularly in the insula, are thought to underlie impaired interoception. As studies specifically investigating this association are largely lacking, this analysis takes an approach that compares meta-analytic results on interoception with recently published meta-analytic results on gray matter reduction in AUD. A systematic literature search identified 25 eligible interoception studies. Activation likelihood estimation (ALE) was used to test for spatial convergence of study results. Overlap between interoception and AUD clusters was tested using conjunction analysis. Meta-analytic connectivity modeling (MACM) and resting-state functional connectivity were used to identify the functional network of interoception and to test where this network overlapped with AUD meta-analytic clusters. The results were characterized using behavioral domain analysis. The interoception ALE identified a cluster in the left middle insula. There was no overlap with clusters of reduced gray matter in AUD. MACM analysis of the interoception cluster revealed a large network located in the insulae, thalami, basal nuclei, cingulate and medial frontal cortices, and pre- and postcentral gyri. Resting state analysis confirmed this result, showing the strongest connections to nodes of the salience- and somatomotor network. Five of the eight clusters that showed a structural reduction in AUD were located within these networks. The behavioral profiles of these clusters were suggestive of higher-level processes such as salience control, somatomotor functions, and skin sensations. The results suggest an altered salience mapping of interoceptive signals in AUD, consistent with current models. Connections to the somatomotor network may be related to action control and integration of skin sensations. Mindfulness-based interventions, pleasurable touch, and (deep) transcranial magnetic stimulation may be targeted interventions that reduce interoceptive deficits in AUD and thus contribute to drug use reduction and relapse prevention.

Lower gastric sensitivity in quiescent inflammatory bowel disease than in irritable bowel syndrome

OBJECTIVE

Visceral hypersensitivity is considered a key symptom in inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), both of which seriously affect health-related quality of life (HrQoL). Previous findings are mostly based on invasive procedures that may interfere with the assessment of visceral perception. The current study, therefore, investigates whether IBD and IBS are characterized by altered perception of 'natural' gastric distensions ('interoception').

METHODS

Twenty IBD patients in remission (13 Crohn's disease, 7 ulcerative colitis), 12 IBS patients, and 20/12 matched healthy control (HC) individuals, respectively, underwent the water load test, in which they could drink ad libitum until the subjective thresholds of satiation (stage 1) and fullness (stage 2) were reached. Gastric motility was assessed using electrogastrography.

RESULTS

IBD patients drank significantly more water until satiation than IBS patients, whereas no differences between patients and HC groups were observed. Electrogastrographic patterns were comparable between groups, suggesting no pathologies in gastric motility in IBD or IBS. The amount of water consumed until satiation negatively correlated with HrQoL related to bowel symptoms in IBD patients, but was positively associated with emotional well-being in IBS patients.

CONCLUSION

Our findings implicate relative gastric hypersensitivity in IBS, and relative hyposensitivity in IBD patients, which are both related to specific HrQoL aspects.

Social Buffering Effects during Craft Activities in Parallel Group Session Revealed by EEG Analysis and Parasympathetic Activity

INTRODUCTION

The therapeutic structure of occupational therapy (OT) includes groups. Although the presence of others is expected to be relaxing due to the social buffering effect and the tend and befriend theory, it has not been sufficiently validated in accordance with the therapeutic structure of OT. The aim of this study was to investigate the electrophysiological evidence for the effectiveness of parallel groups and states of concentration on craft activities used in OT.

METHODS

Thirty healthy young adults were used as controls to measure EEG and autonomic activity during craft activities in three conditions: alone, parallel, and nonparallel. EEG was analyzed using exact low-resolution electromagnetic tomography, and autonomic activity was analyzed using Lorenz plot analysis.

RESULTS

Parasympathetic activity was significantly higher in the parallel condition than in the alone condition. A significant negative correlation was found between current source density and parasympathetic activity in the region centered on the right insular cortex in the α1 band, and functional connectivity in regions including the anterior cingulate cortex and insular cortex was associated with autonomic activity.

CONCLUSION

Craft activities that occurred during frontal midline theta rhythm also increased parasympathetic activity. The results suggest that the parallel groups used in OT and the intensive state of craft activities induce a social buffering effect that increases parasympathetic activity despite the absence of physical contact or social support. This provides evidence for the effectiveness of the therapeutic structure of occupational activities and groups in OT.

Cross-sectional study of retrospective self-reported childhood emotional neglect and inhibitory neurometabolite levels in the pregenual anterior cingulate cortex in adult humans

High childhood emotional maltreatment (CM-EMO) is reported in mood and anxiety disorders. The associations with an increased risk for psychopathology are not fully understood. One potential factor may be through alterations in gamma-Aminobutyric acid (GABA). The pregenual anterior cingulate cortex (pgACC) is an important brain region for emotion processing and its' GABA levels were previously implicated in mood and anxiety disorders pathophysiology. We examined the association between the self-reported CM-EMO in adulthood and GABA + levels in the pgACC and in a control region, anterior mid cingulate cortex. GABA+ and total creatine (tCr) were measured in the pgACC and aMCC voxels in seventy-four healthy volunteers (32 (43%) women, ages 19-54, age [standard deviation] = 27.1 [6.5]) using proton magnetic resonance spectroscopy at 7 T. Childhood Trauma Questionnaire was completed by adult participants to measure retrospective self-reported experience of emotional neglect (CM-EMO-NEG) and emotional abuse (CM-EMO-AB) during childhood. Linear mixed models tested the interaction between the region and the two subscales, and GABA+/tCr ratios, with an adjusted alpha = 0.025. Following, linear models, including with covariates were tested. There was an interaction effect between region and CM-EMO-NEG (B = -0.007, p = 0.009), driven by a negative relationship between CM-EMO-NEG and GABA+/tCr in the pgACC (B = -0.004, p = 0.013). Results for CM-EMO-NEG were robust to inclusion of different covariates (ps < 0.035). There was no interaction effect for the CM-EMO-AB (B = 0.007, p = 0.4). Limitations include cross-sectional measurement and retrospective nature of the CTQ. The findings indicate preliminary importance of inhibitory neurometabolite concentrations in the pgACC for retrospective reporting of CM-EMO-NEG.

Regulation of the central amygdala on intestinal motility and behavior via the lateral hypothalamus in irritable bowel syndrome model mice

BACKGROUND

Impaired bidirectional communication between the gastrointestinal tract and the central nervous system (CNS) is closely related to the development of irritable bowel syndrome (IBS). Studies in patients with IBS have also shown significant activation of the hypothalamus and amygdala. However, how neural circuits of the CNS participate in and process the emotional and intestinal disorders of IBS remains unclear.

METHODS

The GABAergic neural pathway projecting from the central amygdala (CeA) to the lateral hypothalamus (LHA) in mice was investigated by retrograde tracking combined with fluorescence immunohistochemistry. Anxiety, depression-like behavior, and intestinal motility were observed in the water-immersion restraint stress group and the control group. Furthermore, the effects of the chemogenetic activation of the GABAergic neural pathway of CeA-LHA on behavior and intestinal motility, as well as the co-expression of orexin-A and c-Fos in the LHA, were explored.

KEY RESULTS

In our study, Fluoro-Gold retrograde tracking combined with fluorescence immunohistochemistry showed that GABAergic neurons in the CeA were projected to the LHA. The microinjection of the gamma-aminobutyric acid (GABA) receptor antagonist into the LHA relieved anxiety, depression-like behavior, and intestinal motility disorder in the IBS mice. The chemogenetic activation of GABAergic neurons in the CeA-LHA pathway led to anxiety, depression-like behavior, and intestinal motility disorder. In addition, GABAergic neurons in the CeA-LHA pathway inhibited the expression of orexin-A in the LHA, and orexin-A was co-expressed with GABAA receptors.

CONCLUSIONS & INFERENCES

The CeA-LHA GABAergic pathway might participate in the occurrence and development of IBS by regulating orexin-A neurons.

Research hotspots and trends in visceral pain research: A global comprehensive bibliometric analysis

Background

Visceral pain is a complex and heterogeneous disorder that is considered more prominent compared to somatic pain, due to its multiple and complex causes and accompanying emotional and mood disorders. Research has become increasingly extensive over the years, but a bibliometric analysis of this field is lacking. The aim of this study was to analyze global research trends in visceral pain over the past 40 years through visual analysis.

Methods

We conducted a comprehensive search of the literature from January 1981 to December 2021 using the Web of Science core database. The medical subject term 'visceral pain' was searched. We used CiteSpace and VOSviewer for bibliometric analysis and network visualization, including top-ranked authors, keywords, research collaborations, and literature co-occurrence network analysis.

Results

A total of 5,047 articles were included in the analysis. The number of articles on visceral pain has continued to grow steadily over the past 40 years. The United States (1,716 articles), University of California (159 articles), and Neurogastroenterology and Motility (276 articles) were the country, institution, and journal with the most publications, respectively. Keyword analysis showed that inflammation, visceral hypersensitivity, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), anxiety, and quality of life were the research trends and priorities in this research field.

Conclusion

Visceral pain-related research has received increasing attention in recent decades. However, there are still many unresolved issues in the field of visceral pain, such as the specific molecular mechanisms and clinical treatments between visceral pain and inflammation, IBD, IBS, anxiety, and quality of life, which may require further exploration based on modern scientific and technological means and more basic research, especially for the therapeutic targets of visceral pain, which may become a hot spot for future research and provide guidance for the treatment of clinical diseases related to visceral pain.

A Rome Working Team Report on Brain-Gut Behavior Therapies for Disorders of Gut-Brain Interaction

BACKGROUND AND AIMS

This Rome Foundation Working Team Report reflects the consensus of an international interdisciplinary team of experts regarding the use of behavioral interventions, specifically brain-gut behavior therapies (BGBTs), in patients with disorders of gut-brain interaction (DGBIs).

METHODS

The committee members reviewed the extant scientific literature and, when possible, addressed gaps in this literature through the lens of their clinical and scientific expertise. The Delphi method was used to create consensus on the goals, structure, and framework before writing the report. The report is broken into 5 parts: 1) definition and evidence for BGBT, 2) the gut-brain axis as the mechanistic basis for BGBT, 3) targets of BGBTs, 4) common and unique therapeutic techniques seen in BGBT, and 5) who and how to refer for BGBT.

RESULTS

We chose to not only review for the reader the 5 existing classes of BGBT and their evidence, but to connect DGBI-specific behavioral targets and techniques as they relate directly, or in some cases indirectly, to the gut-brain axis. In doing so, we expect to increase gastrointestinal providers' confidence in identifying and referring appropriate candidates for BGBT and to support clinical decision making for mental health professionals providing BGBT.

CONCLUSIONS

Both gastrointestinal medical providers and behavioral health providers have an opportunity to optimize care for DGBIs through a collaborative integrated approach that begins with an effective patient-provider relationship, thoughtful communication about the brain-gut axis and, when appropriate, a well communicated referral to BGBT.

Event-based control of autonomic and emotional states by the anterior cingulate cortex

Despite being an intensive area of research, the function of the anterior cingulate cortex (ACC) remains somewhat of a mystery. Human imaging studies implicate the ACC in various cognitive functions, yet surgical ACC lesions used to treat emotional disorders have minimal lasting effects on cognition. An alternative view is that ACC regulates autonomic states, consistent with its interconnectivity with autonomic control regions and that stimulation evokes changes in autonomic/emotional states. At the cellular level, ACC neurons are highly multi-modal and promiscuous, and can represent a staggering array of task events. These neurons nevertheless combine to produce highly event-specific ensemble patterns that likely alter activity in downstream regions controlling emotional and autonomic tone. Since neuromodulators regulate the strength of the ensemble activity patterns, they would regulate the impact these patterns have on downstream targets. Through these mechanisms, the ACC may determine how strongly to react to the very events its ensembles represent. Pathologies arise when specific event-related representations gain excessive control over autonomic/emotional states.

A lateralized model of the pain-depression dyad

Chronic pain and depression are two frequently co-occurring and debilitating conditions. Even though the former is treated as a physical affliction, and the latter as a mental illness, both disorders closely share neural substrates. Here, we review the association of pain with depression, especially when symptoms are lateralized on either side of the body. We also explore the overlapping regions in the forebrain implicated in these conditions. Finally, we synthesize these findings into a model, which addresses gaps in our understanding of comorbid pain and depression. Our lateralized pain-depression dyad model suggests that individuals diagnosed with depression should be closely monitored for pain symptoms in the left hemibody. Conversely, for patients in pain, with the exception of acute pain with a known source, referrals in today's pain centers for psychological evaluation should be part of standard practice, within the framework of an interdisciplinary approach to pain treatment.

The influence of motivation and emotion on sensorimotor rhythm-based brain-computer interface performance

While decades of research have investigated and technically improved brain-computer interface (BCI)-controlled applications, relatively little is known about the psychological aspects of brain-computer interfacing. In 35 healthy students, we investigated whether extrinsic motivation manipulated via monetary reward and emotional state manipulated via video and music would influence behavioral and psychophysiological measures of performance with a sensorimotor rhythm (SMR)-based BCI. We found increased task-related brain activity in extrinsically motivated (rewarded) as compared with nonmotivated participants but no clear effect of emotional state manipulation. Our experiment investigated the short-term effect of motivation and emotion manipulation in a group of young healthy subjects, and thus, the significance for patients in the locked-in state, who may be in need of a BCI, remains to be investigated.

Negative Effects of Mobile Phone Addiction Tendency on Spontaneous Brain Microstates: Evidence From Resting-State EEG

The prevalence of mobile phone addiction (MPA) has increased rapidly in recent years, and it has had a certain negative impact on emotions (e.g., anxiety and depression) and cognitive capacities (e.g., executive control and working memory). At the level of neural circuits, the continued increase in activity in the brain regions associated with addiction leads to neural adaptations and structural changes. At present, the spontaneous brain microstates that could be negatively influenced by MPA are unclear. In this study, the temporal characteristics of four resting-state electroencephalogram (RS-EEG) microstates (MS1, MS2, MS3, and MS4) related to mobile phone addiction tendency (MPAT) were investigated using the Mobile Phone Addiction Tendency Scale (MPATS). We attempted to analyze the correlation between MPAT and corresponding microstates and provide evidence to explain the brain and behavioral changes caused by MPA. The results showed that the total score of the MPATS was positively correlated with the duration of MS1, related to phonological processing and negatively correlated with the duration of MS2, related to visual or imagery processing, and MS4, related to the attentional network; the score of the withdrawal symptoms subscale was additionally associated with duration of MS3, related to the cingulo-opercular emotional network. Based on these results, we believe that MPAT may have some negative effects on attentional networks and sensory brain networks; moreover, withdrawal symptoms may induce some negative emotions.

Brain Functional Alternations of the Pain-related Emotional and Cognitive Regions in Patients with Chronic Shoulder Pain

Objective

Chronic shoulder pain (CSP) is a common health problem associated with shoulder dysfunction and persistent pain for many different reasons. However, the studies of pain-related functional brain regions in CSP have been poorly investigated. The main purpose of our study was to observe whether there are abnormal functional changes in brain regions in patients with CSP by using functional magnetic resonance imaging (fMRI).

Patients and Methods

We compared the differences of brain regions between 37 patients with CSP and 24 healthy controls (HC) using regional homogeneity (ReHo) method. The patients with chronic shoulder pain and healthy controls were matched for age and gender. Brain regions which had abnormal ReHo values were defined as seed region of interests. The approach of seed-based functional connectivity (FC) was further performed to analyze the connectivity between the seeds and whole brain regions. The relationship between abnormal regions and current clinical pain was also evaluated.

Results

Compared to healthy controls, the patients with CSP showed increased ReHo values in the left middle temporal gyrus and decreased ReHo values in right orbitofrontal cortex (OFC). The seed-based analyses demonstrated decreased connectivity between the right OFC and right rectus, superior frontal gyrus in patients with chronic shoulder pain. However, a correlation between ReHo values and clinical characteristics in CSP patients was not found.

Conclusion

The observed results indicate that there are abnormal ReHo values in brain regions of patients with CSP, especially in the OFC and middle temporal gyrus. Our findings demonstrate that the experience of CSP patients may be mainly associated with cognitive-affective pain processing, rather than nociception.

Building the bodily self-awareness: Evidence for the convergence between interoceptive and exteroceptive information in a multilevel kernel density analysis study

Exteroceptive and interoceptive signals shape and sustain the bodily self-awareness. The existence of a set of brain areas, supporting the integration of information coming from the inside and the outside of the body in building the sense of bodily self-awareness has been postulated, yet the evidence remains limited, a matter of discussion never assessed quantitatively. With the aim of unrevealing where in the brain interoceptive and exteroceptive signals may converge, we performed a meta-analysis on imaging studies of the sense of body ownership, modulated by external visuotactile stimulation, and studies on interoception, which involves the self-awareness for internal bodily sensations. Using a multilevel kernel density analysis, we found that processing of stimuli of the two domains converges primarily in the supramarginal gyrus bilaterally. Furthermore, we found a right-lateralized set of areas, including the precentral and postcentral, and superior temporal gyri. We discuss these results and propose this set of areas as ideal candidates to match multiple body-related signals contributing to the creation of a multidimensional representation of the bodily self.

Down-regulation of HTR1A-modulated ACC activation contributes to stress-induced visceral hyperalgesia in rats

BACKGROUND

Long-term stress was suggested to cause visceral hypersensitivity and promote functional gastrointestinal disorders (FGIDs). Some brain regions such as the anterior cingulate cortex (ACC) may play an important role for generating visceral hypersensitivity; however, its molecular mechanisms are not clear. This study aimed to explore the role of 5-HT1A receptors (HTR1As) in activating ACC and corresponding mechanism, in stress-induced visceral hyperalgesia rats.

METHODS

The VH rat model was established by chronic water avoidance stress (WAS), and the visceral sensitivity was measured by electromyogram. Rat's anxiety-like behaviors were evaluated by the open field test (OFT) and elevated plus maze (EPM). To overexpress or down-regulate HTR1A expression, HTR1A-specific lentivirus expressing the green fluorescent protein was administered into the ACC. Protein expression levels were observed by Western blot.

RESULTS

The protein expression of HTR1A in bilateral ACC in WAS group was significantly lower than that in normal control (NC) and Sham-WAS groups, while the levels of c-fos in the ACC of WAS rats were significantly higher. Down-regulation of HTR1As could induce VH in control rats with the increased expression of c-fos, p-ERK, and p-Akt in ACC, while up-regulation of HTR1As in the ACC could partly inhibit ACC sensitization and stress-induced visceral hyperalgesia.

CONCLUSIONS & INFERENCES

Down-regulation of HTR1As modulates ACC activation probably through activating ERK and Akt pathways, thus contributes to the formation of stress-induced visceral hyperalgesia.

The gut-brain axis in health neuroscience: implications for functional gastrointestinal disorders and appetite regulation

Over the past few years, scientific interest in the gut-brain axis (i.e., the bidirectional communication system between the gastrointestinal tract and the brain) has exploded, mostly due to the identification of the gut microbiota as a novel key player in this communication. However, important progress has also been made in other aspects of gut-brain axis research, which has been relatively underemphasized in the review literature. Therefore, in this review, we provide a comprehensive, although not exhaustive, overview of recent research on the functional neuroanatomy of the gut-brain axis and its relevance toward the multidisciplinary field of health neuroscience, excluding studies on the role of the gut microbiota. More specifically, we first focus on irritable bowel syndrome, after which we outline recent findings on the role of the gut-brain axis in appetite and feeding regulation, primarily focusing on the impact of subliminal nutrient-related gut-brain signals. We conclude by providing future perspectives to facilitate translation of the findings from gut-brain axis neuroscientific research to clinical applications in these domains.

Understanding Neurogastroenterology From Neuroimaging Perspective: A Comprehensive Review of Functional and Structural Brain Imaging in Functional Gastrointestinal Disorders

This review provides a comprehensive overview of brain imaging studies of the brain-gut interaction in functional gastrointestinal disorders (FGIDs). Functional neuroimaging studies during gut stimulation have shown enhanced brain responses in regions related to sensory processing of the homeostatic condition of the gut (homeostatic afferent) and responses to salience stimuli (salience network), as well as increased and decreased brain activity in the emotional response areas and reduced activation in areas associated with the top-down modulation of visceral afferent signals. Altered central regulation of the endocrine and autonomic nervous responses, the key mediators of the brain-gut axis, has been demonstrated. Studies using resting-state functional magnetic resonance imaging reported abnormal local and global connectivity in the areas related to pain processing and the default mode network (a physiological baseline of brain activity at rest associated with self-awareness and memory) in FGIDs. Structural imaging with brain morphometry and diffusion imaging demonstrated altered gray- and white-matter structures in areas that also showed changes in functional imaging studies, although this requires replication. Molecular imaging by magnetic resonance spectroscopy and positron emission tomography in FGIDs remains relatively sparse. Progress using analytical methods such as machine learning algorithms may shift neuroimaging studies from brain mapping to predicting clinical outcomes. Because several factors contribute to the pathophysiology of FGIDs and because its population is quite heterogeneous, a new model is needed in future studies to assess the importance of the factors and brain functions that are responsible for an optimal homeostatic state.

Migraine Pain Location and Measures of Healthcare Use and Distress: An Observational Study

Introduction

Lateralized pain is a core diagnostic feature of migraine. In previous research, left-sided spinal pain was more frequent and associated with greater emotional distress and healthcare use than right-sided pain. We hypothesized therefore that patients with left-sided head pain might experience higher levels of distress or healthcare use than those with right-sided or bilateral pain.

Methods

Medical record information was extracted for 477 randomly selected patients with migraine seen in 2011 in a tertiary headache clinic. This included demographic data, pain location, handedness, comorbid psychiatric diagnoses, medical and emergency department visits, and use of selected headache medications.

Results and Discussion

Two hundred twenty-eight of four hundred seventy-seven (47.8%) patients reported lateralized pain, of which 107 (47.9%) patients were right sided compared with 65 (28.5%) left-sided patients (p=0.001), while 56 (24.5%) reported unilateral pain with no side predominance. Contrary to expectations, with the exception of self-reported posttraumatic stress disorder, there were no statistically significant differences between left and right in measures of psychiatric distress, emergency department visits, or healthcare use.

Conclusion

Although unilateral pain location can be helpful in making a migraine diagnosis, it does not appear to have additional clinical implications. Additionally, its absence does not rule out a diagnosis of migraine since more than half of migraineurs have bilateral head pain.

Validation of the oesophageal hypervigilance and anxiety scale for chronic oesophageal disease

BACKGROUND

Oesophageal hypervigilance and anxiety can drive symptom experience in chronic oesophageal conditions, including gastro-oesophageal reflux disease, achalasia and functional oesophageal disorders. To date, no validated self-report measure exists to evaluate oesophageal hypervigilance and anxiety.

AIMS

This study aims to develop a brief and reliable questionnaire assessing these constructs, the oesophageal hypervigilance and anxiety scale (EHAS).

METHODS

Questions for the EHAS were drawn from 4 existing validated measures that assessed hypervigilance and anxiety adapted for the oesophagus. Patients who previously underwent high-resolution manometry testing at a university-based oesophageal motility clinic were retrospectively identified. Patients were included in the analysis if they completed the EHAS as well as questionnaires assessing symptom severity and health-related quality of life at the time of the high-resolution manometry.

RESULTS

Nine hundred and eighty-two patients aged 18-85 completed the study. The EHAS demonstrates excellent internal consistency (α = 0.93) and split-half reliability (Guttman = 0.87). Inter-item correlations indicated multicollinearity was not achieved; thus, no items were removed from the original 15-item scale. Principal components factor analysis revealed two subscales measuring symptom-specific anxiety and symptom-specific hypervigilance. Construct validity for total and subscale scores was supported by positive correlations with symptom severity and negative correlations with health-related quality of life.

CONCLUSIONS

The EHAS is a 15-item scale assessing oesophageal hypervigilance and symptom-specfic anxiety. The EHAS could be useful in evaluating the role of these constructs in several oesophageal conditions in which hypersensitivity, hypervigilance and anxiety may contribute to symptoms and impact treatment outcomes.

"Luteal Analgesia": Progesterone Dissociates Pain Intensity and Unpleasantness by Influencing Emotion Regulation Networks

Background: Pregnancy-induced analgesia is known to occur in association with the very high levels of estradiol and progesterone circulating during pregnancy. In women with natural ovulatory menstrual cycles, more modest rises in these hormones occur on a monthly basis. We therefore hypothesized that the high estradiol high progesterone state indicative of ovulation would be associated with a reduction in the pain experience. Methods: We used fMRI and a noxious thermal stimulus to explore the relationship between sex steroid hormones and the pain experience. Specifically, we assessed the relationship with stimulus-related activity in key regions of networks involved in emotion regulation, and functional connectivity between these regions. Results: We demonstrate that physiologically high progesterone levels are associated with a reduction in the affective component of the pain experience and a dissociation between pain intensity and unpleasantness. This dissociation is related to decreased functional connectivity between the inferior frontal gyrus and amygdala. Moreover, we have shown that in the pre-ovulatory state, the traditionally "male" sex hormone, testosterone, is the strongest hormonal regulator of pain-related activity and connectivity within the emotional regulation network. However, following ovulation the traditionally "female" sex hormones, estradiol and progesterone, appear to dominate. Conclusions: We propose that a phenomenon of "luteal analgesia" exists with potential reproductive advantages.

The stress concept in gastroenterology: from Selye to today

More than eighty years after Hans Selye (1907-1982) first developed a concept describing how different types of environmental stressors affect physiological functions and promote disease development (called the "general adaptation syndrome") in 1936, we herein review advances in theoretical, mechanistic, and clinical knowledge in stress research, especially in the area of gastroenterology, and summarize progress and future perspectives arising from an interdisciplinary psychoneurobiological framework in which genetics, epigenetics, and other advanced ( omics) technologies in the last decade continue to refine knowledge about how stress affects the brain-gut axis in health and gastrointestinal disease. We demonstrate that neurobiological stress research continues to be a driving force for scientific progress in gastroenterology and related clinical areas, inspiring translational research from animal models to clinical applications, while highlighting some areas that remain incompletely understood, such as the roles of sex/gender and gut microbiota in health and disease. Future directions of research should include not only the genetics of the stress response and resilience but also epigenetic contributions.

The Role of Esophageal Hypersensitivity in Functional Esophageal Disorders

The Rome IV diagnostic criteria delineates 5 functional esophageal disorders which include functional chest pain, functional heartburn, reflux hypersensitivity, globus, and functional dysphagia. These are a heterogenous group of disorders which, despite having characteristic symptom profiles attributable to esophageal pathology, fail to demonstrate any structural, motility or inflammatory abnormalities on standard clinical testing. These disorders are associated with a marked reduction in patient quality of life, not least considerable healthcare resources. Furthermore, the pathophysiology of these disorders is incompletely understood. In this narrative review we provide the reader with an introductory primer to the structure and function of esophageal perception, including nociception that forms the basis of the putative mechanisms that may give rise to symptoms in functional esophageal disorders. We also discuss the provocative techniques and outcome measures by which esophageal hypersensitivity can be established.

The Insula: A "Hub of Activity" in Migraine

The insula, a "cortical hub" buried within the lateral sulcus, is involved in a number of processes including goal-directed cognition, conscious awareness, autonomic regulation, interoception, and somatosensation. While some of these processes are well known in the clinical presentation of migraine (i.e., autonomic and somatosensory alterations), other more complex behaviors in migraine, such as conscious awareness and error detection, are less well described. Since the insula processes and relays afferent inputs from brain areas involved in these functions to areas involved in higher cortical function such as frontal, temporal, and parietal regions, it may be implicated as a brain region that translates the signals of altered internal milieu in migraine, along with other chronic pain conditions, through the insula into complex behaviors. Here we review how the insula function and structure is altered in migraine. As a brain region of a number of brain functions, it may serve as a model to study new potential clinical perspectives for migraine treatment.

Influence of Interoceptive Fear Learning on Visceral Perception

OBJECTIVES

Interoceptive fear learning and generalization have been hypothesized to play a key role in unexplained abdominal and esophageal pain in patients with functional gastrointestinal disorders. However, there is no experimental evidence demonstrating that fear learning and generalization to visceral sensations can be established in humans and alter visceral perception.

METHODS

In a novel fear learning-generalization paradigm, an innocuous esophageal balloon distension served as conditioned stimulus (CS), and distensions at three different pressure levels around the pain detection threshold were used as generalization stimuli. During fear learning, the CS was paired with a painful electrical stimulus (unconditioned stimulus) in the conditioning group (n = 30), whereas in the control group (n = 30), the unconditioned stimulus was delivered alone. Before and after fear learning, visceral perception thresholds for first sensation, discomfort, and pain and visceral discrimination sensitivity were assessed.

RESULTS

Fear learning was established in the conditioning group only (potentiated eye-blink startle to the CS (t(464.06) = 3.17, p = .002), and fear generalization to other stimulus intensities was observed (t(469.12) = 2.97, p = .003; t(464.29) = 4.17, p < .001). The thresholds for first sensation habituated in the control group, whereas it remained constant in the conditioning group (F(1,43) = 9.77, p = .003).

CONCLUSIONS

These data show that fear learning using visceral stimuli induces fear generalization and influences visceral perception. These findings support the idea that in functional gastrointestinal disorder, fear learning and generalization can foster gastrointestinal-specific anxiety and contribute to visceral hypersensitivity.

Esophageal acid stimulation alters insular cortex functional connectivity in gastroesophageal reflux disease

BACKGROUND

The insula plays a significant role in the interoceptive processing of visceral stimuli. We have previously shown that gastroesophageal reflux disease (GERD) patients have increased insular cortex activity during esophageal stimulation, suggesting a sensitized esophago-cortical neuraxis. However, information regarding the functional connectivity (FC) of the insula during visceral stimulation is lacking. The primary aim of this study was to investigate the FC of insular subregions during esophageal acid stimulation.

METHODS

Functional imaging data were obtained from 12 GERD patients and 14 healthy subjects during four steady state conditions: (i) presence of transnasal esophageal catheter (pre-infusion); (ii) neutral solution; (iii) acid infusion; (iv) presence of transnasal esophageal catheter following infusions (post-infusion). The insula was parcellated into six regions of interest. FC maps between each insular ROI and interoceptive regions were created. Differences in FC between GERD patients and healthy subjects were determined across the 4 study conditions.

KEY RESULTS

All GERD patients experienced heartburn during and after esophageal acidification. Significant differences between GERD patients and healthy subjects were seen in: (i) insula-thalamic FC (neutral solution infusion, acid infusion, post-infusion); (ii) insula-amygdala FC (acid infusion, post-infusion); (iii) insula-hippocampus and insula-cingulate FC (post-infusion).

CONCLUSIONS & INFERENCES

Esophageal stimulation in GERD patients revealed significant insular cortex FC differences with regions involved in viscerosensation and interoception. The results of our study provide further evidence that the insula, located at the transition of afferent physiologic information to human feelings, is essential for both visceral homeostasis and the experience of heartburn in GERD patients.

Visually induced nausea causes characteristic changes in cerebral, autonomic and endocrine function in humans

An integrated understanding of the physiological mechanisms involved in the genesis of nausea remains lacking. We aimed to describe the psychophysiological changes accompanying visually induced motion sickness, using a motion video, hypothesizing that differences would be evident between subjects who developed nausea in comparison to those who did not. A motion, or a control, stimulus was presented to 98 healthy subjects in a randomized crossover design. Validated questionnaires and a visual analogue scale (VAS) were used for the assessment of anxiety and nausea. Autonomic and electrogastrographic activity were measured at baseline and continuously thereafter. Plasma vasopressin and ghrelin were measured in response to the motion video. Subjects were stratified into quartiles based on VAS nausea scores, with the upper and lower quartiles considered to be nausea sensitive and resistant, respectively. Twenty-eight subjects were exposed to the motion video during functional neuroimaging. During the motion video, nausea-sensitive subjects had lower normogastria/tachygastria ratio and cardiac vagal tone but higher cardiac sympathetic index in comparison to the control video. Furthermore, nausea-sensitive subjects had decreased plasma ghrelin and demonstrated increased activity of the left anterior cingulate cortex. Nausea VAS scores correlated positively with plasma vasopressin and left inferior frontal and middle occipital gyri activity and correlated negatively with plasma ghrelin and brain activity in the right cerebellar tonsil, declive, culmen, lingual gyrus and cuneus. This study demonstrates that the subjective sensation of nausea is associated with objective changes in autonomic, endocrine and brain networks, and thus identifies potential objective biomarkers and targets for therapeutic interventions.

Brain-based Correlations Between Psychological Factors and Functional Dyspepsia

Background/Aims

Increasing evidence shows involvement of psychological disorders in functional dyspepsia (FD), but how psychological factors exert their influences upon FD remains largely unclear. The purpose of the present study was to explore the brain-based correlations of psychological factors and FD.

Methods

Based on Fluorine-18-deoxyglucose positron emission tomography-computed tomography, the altered cerebral glycometabolism was investigated in 40 FD patients compared with 20 healthy controls during resting state using statistical parametric mapping software.

Results

FD patients exhibited increased glucose metabolism in multiple regions relative to controls (P < 0.001, family-wise error corrected). After controlling for the dyspeptic symptoms, increased aberrations persisted within the insula, anterior cingulate cortex (ACC), middle cingulate cortex (MCC) and middle frontal cortex (midFC), which was related to anxiety and depression score. Interestingly, FD patients without anxiety/depression symptoms also showed increased glycometabolism within the insula, ACC, MCC and midFC. Moreover, FD patients with anxiety/depression symptoms exhibited more significant hypermetabolism within the above 4 sites compared with patients without anxiety/depression symptoms.

Conclusions

Our results suggested that the altered cerebral glycometabolism may be in a vicious cycle of psychological vulnerabilities and increased gastrointestinal symptoms.

Functional brain imaging in gastroenterology: to new beginnings

With more than 100 studies published over the past two decades, functional brain imaging research in gastroenterology has become an established field; one that has enabled improved insight into the supraspinal responses evoked by gastrointestinal stimulation both in health and disease. However, there remains considerable inter-study variation in the published results, largely owing to methodological differences in stimulation and recording techniques, heterogeneous patient selection, lack of control for psychological factors and so on. These issues with reproducibility, although not unique to studies of the gastrointestinal tract, can lead to unjustified inferences. To obtain consistent and more clinically relevant results, there is a need to optimize and standardize brain imaging studies across different centres. In addition, the use of complementary and more novel brain imaging modalities and analyses, which are now being used in other fields of research, might help unravel the factors at play in functional gastrointestinal disorders. This Review highlights the areas in which functional brain imaging has been useful and what it has revealed, the areas that are in need of improvement, and finally suggestions for future directions.

Stress and visceral pain: focusing on irritable bowel syndrome

Recent advances in brain science have shown that the brain function encoding emotion depends on interoceptive signals such as visceral pain. Visceral pain arose early in our evolutionary history. Bottom-up processing from gut-to-brain and top-down autonomic/neuroendocrine mechanisms in brain-to-gut signaling constitute a circuit. Brain imaging techniques have enabled us to depict the visceral pain pathway as well as the related emotional circuit. Irritable bowel syndrome (IBS) is characterized by chronic recurrent abdominal pain or abdominal discomfort associated with bowel dysfunction. It is also thought to be a disorder of the brain-gut link associated with an exaggerated response to stress. Corticotropin-releasing hormone (CRH), a major mediator of the stress response in the brain-gut axis, is an obvious candidate in the pathophysiology of IBS. Indeed, administration of CRH has been shown to aggravate the visceral sensorimotor response in IBS patients, and the administration of peptidergic CRH antagonists seems to alleviate IBS pathophysiology. Serotonin (5-HT) is another likely candidate associated with brain-gut function in IBS, as 5-HT3 antagonists, 5-HT4 agonists, and antidepressants were demonstrated to regulate 5-HT neurotransmission in IBS patients. Autonomic nervous system function, the neuroimmune axis, and the brain-gut-microbiota axis show specific profiles in IBS patients. Further studies on stress and visceral pain neuropathways in IBS patients are warranted.

Sex differences in brain response to anticipated and experienced visceral pain in healthy subjects

Women demonstrate higher pain sensitivity and prevalence of chronic visceral pain conditions such as functional gastrointestinal disorders than men. The role of sex differences in the brain processing of visceral pain is still unclear. In 16 male and 16 female healthy subjects we compared personality, anxiety levels, skin conductance response (SCR), and brain processing using functional MRI during anticipation and pain induced by esophageal distension at pain toleration level. There was no significant difference in personality scores, anxiety levels, SCR, and subjective ratings of pain between sexes. In group analysis, both men and women demonstrated a similar pattern of brain activation and deactivation during anticipation and pain consistent with previous reports. However, during anticipation women showed significantly greater activation in the cuneus, precuneus, and supplementary motor area (SMA) and stronger deactivation in the right amygdala and left parahippocampal gyrus, whereas men demonstrated greater activation in the cerebellum. During pain, women demonstrated greater activation in the midcingulate cortex, anterior insula, premotor cortex, and cerebellum and stronger deactivation in the caudate, whereas men showed increased activity in the SMA. The pattern of brain activity suggests that, during anticipation, women may demonstrate stronger limbic inhibition, which is considered to be a cognitive modulation strategy for impending painful stimulation. During pain, women significantly activate brain areas associated with the affective and motivation components of pain. These responses may underlie the sex differences that exist in pain conditions, whereby women may attribute more emotional importance to painful stimuli compared with men.

The role of psychosocial factors and psychiatric disorders in functional dyspepsia

In this Review, after a brief historical introduction, we first provide an overview of epidemiological studies that demonstrate an association between functional dyspepsia and psychological traits, states or psychiatric disorders. These studies suggest an important intrinsic role for psychosocial factors and psychiatric disorders, especially anxiety and depression, in the aetiopathogenesis of functional dyspepsia, in addition to their putative influence on health-care-seeking behaviour. Second, we describe pathophysiological evidence on how psychosocial factors and psychiatric disorders might exert their role in functional dyspepsia. Novel insights from functional brain imaging studies regarding the integration of gut-brain signals, processed in homeostatic-interoceptive brain regions, with input from the exteroceptive system, the reward system and affective and cognitive circuits, help to clarify the important role of psychological processes and psychiatric morbidity. We therefore propose an integrated model of functional dyspepsia as a disorder of gut-brain signalling, supporting a biopsychosocial approach to the diagnosis and management of this disorder.

Effects of arterial cannulation stress on regional cerebral blood flow in major depressive disorder

Individuals with major depressive disorder (MDD) display abnormal neurophysiological responses to psychological stress but little is known about their neurophysiological responses to physiological stressors. Using [¹⁵O-H₂O] positron emission tomography we assessed whether the regional cerebral blood flow (rCBF) response to arterial cannulation differed between patients with MDD and healthy controls (HCs). Fifty-one MDD patients and 62 HCs were scanned following arterial cannulation and 15 MDD patients and 17 HCs were scanned without arterial cannulation. A region-of-interest analysis showed that a significantly increased rCBF of the anterior cingulate cortex and right amygdala was associated with arterial cannulation in MDD. A whole brain analysis showed increased rCBF of the right post-central gyrus, left temporopolar cortex, and right amygdala during arterial cannulation in MDD patients. The rCBF in the right amygdala was significantly correlated with depression severity. Conceivably, the limbic response to invasive physical stress is greater in MDD subjects than in HCs.

'Idiopathic' intestinal failure--the importance of identifying and treating primary psychopathology

BACKGROUND

Gastrointestinal neuromuscular disorders (GINMD) are an important cause of intestinal failure (IF). We present six cases of IF in whom a diagnosis of GINMD was initially suspected, but in whom psychopathology was discovered to be the primary etiology.

METHODS

(i) Six consecutive cases referred to our unit with IF, initially presumed to be due to GINMD, were selected. Informed consent was obtained from all patients. Case notes were reviewed for salient clinical information. (ii) A literature search was performed to ascertain the epidemiology of psychopathology in IF and the current evidence for the management of severe functional GI disorders with a multidisciplinary psychiatric approach.

KEY RESULTS

(i)All six cases required multidisciplinary psychiatric management in a specialized psychiatric unit that included the use of antidepressants, antipsychotics, mood stabilizers, and Electroconvulsive therapy in addition to nutritional support via enteral or parenteral routes. (ii) The evidence base for the treatment of severe FGIDs is sparse.

CONCLUSIONS & INFERENCES

There is a need for additional reporting of such cases and further research. Our experience would suggest that a delay in the involvement of a specialist liaison psychiatrist has the potential to be life threatening in such cases. This may be more likely with greater severity, where the apparent predominance of 'physical' symptoms generates reluctance in both patient and physician to consider a psychiatric etiology and also appears to occur due to a lengthier investigative process than existed previously. We therefore propose that the provision of a specialist psychiatric assessment for all patients presenting with IF is indicated at the point of initial clinical contact, based upon the substantial clinical benefit it has the potential to confer upon a significant minority. This process need not delay investigation, which can continue as indicated in parallel, but can be life-saving.

Unmasking the mysteries of the habenula in pain and analgesia

The habenula is a small bilateral structure in the posterior-medial aspect of the dorsal thalamus that has been implicated in a remarkably wide range of behaviors including olfaction, ingestion, mating, endocrine and reward function, pain and analgesia. Afferent connections from forebrain structures send inputs to the lateral and medial habenula where efferents are mainly projected to brainstem regions that include well-known pain modulatory regions such as the periaqueductal gray and raphe nuclei. A convergence of preclinical data implicates the region in multiple behaviors that may be considered part of the pain experience including a putative role in pain modulation, affective, and motivational processes. The habenula seems to play a role as an evaluator, acting as a major point of convergence where external stimuli is received, evaluated, and redirected for motivation of appropriate behavioral response. Here, we review the role of the habenula in pain and analgesia, consider its potential role in chronic pain, and review more recent clinical and functional imaging data of the habenula from animals and humans. Even through the habenula is a small brain structure, advances in structural and functional imaging in humans should allow for further advancement of our understanding of its role in pain and analgesia.

Localization of pain-related brain activation: a meta-analysis of neuroimaging data

A meta-analysis of 140 neuroimaging studies was performed using the activation-likelihood-estimate (ALE) method to explore the location and extent of activation in the brain in response to noxious stimuli in healthy volunteers. The first analysis involved the creation of a likelihood map illustrating brain activation common across studies using noxious stimuli. The left thalamus, right anterior cingulate cortex (ACC), bilateral anterior insulae, and left dorsal posterior insula had the highest likelihood of being activated. The second analysis contrasted noxious cold with noxious heat stimulation and revealed higher likelihood of activation to noxious cold in the subgenual ACC and the amygdala. The third analysis assessed the implications of using either a warm stimulus or a resting baseline as the control condition to reveal activation attributed to noxious heat. Comparing noxious heat to warm stimulation led to peak ALE values that were restricted to cortical regions with known nociceptive input. The fourth analysis tested for a hemispheric dominance in pain processing and showed the importance of the right hemisphere, with the strongest ALE peaks and clusters found in the right insula and ACC. The fifth analysis compared noxious muscle with cutaneous stimuli and the former type was more likely to evoke activation in the posterior and anterior cingulate cortices, precuneus, dorsolateral prefrontal cortex, and cerebellum. In general, results indicate that some brain regions such as the thalamus, insula and ACC have a significant likelihood of activation regardless of the type of noxious stimuli, while other brain regions show a stimulus-specific likelihood of being activated.

Neuroticism influences brain activity during the experience of visceral pain

BACKGROUND & AIMS

One particularly important individual dynamic known to influence the experience of pain is neuroticism, of which little is known about in visceral pain research. Our aim was to study the relationship between neuroticism, psychophysiologic response, and brain processing of visceral pain.

METHODS

Thirty-one healthy volunteers (15 male; age range, 22-38 years) participated in the study. The Eysenck Personality Questionnaire was used to assess neuroticism. Skin conductance level, pain ratings, and functional magnetic resonance imaging data were acquired during anticipation of pain and painful esophageal distention. The effect of neuroticism was assessed using correlation analysis.

RESULTS

There was a wide spread of neuroticism scores (range, 0-22) but no influence of neuroticism on skin conductance level and pain tolerance or pain ratings. However, a positive correlation between brain activity and neuroticism during anticipation was found in regions associated with emotional and cognitive pain processing, including the parahippocampus, insula, thalamus, and anterior cingulate cortex. These regions showed a negative correlation with neuroticism during pain (P < .001).

CONCLUSIONS

This study provides novel data suggesting higher neuroticism is associated with engagement of brain regions responsible for emotional and cognitive appraisal during anticipation of pain but reduced activity in these regions during pain. This may reflect a maladaptive mechanism in those with higher neuroticism that promotes overarousal during anticipation and avoidance coping during pain.

Pelvic pain in women: clinical and scientific aspects

PURPOSE OF REVIEW

Pelvic pain is a common complaint of women that is frequently poorly managed. This review considers the current understanding of the mechanisms of pain perception and the development of chronic pain in the context of three gynaecological pain conditions. Recent advances in the management of these conditions are then discussed.

RECENT FINDINGS

Persistent pelvic pain is associated with central changes, reflected by alterations in psychology, brain structure and function, and dysfunction of the hypothalamic-pituitary-adrenal axis. The many similarities among the conditions support the notion that chronic pain should be treated as a symptom in its own right, however, obtaining a diagnosis remains important to patients. Few new treatments have been developed recently, however, older treatments are being subjected to more rigorous testing and improvements in phenotyping should lead to better design of clinical trials.

SUMMARY

Good quality, well designed clinical trials are urgently required to improve the treatment of pelvic pain in women. However, a variety of successful treatments exist and outcomes can be optimized by individualizing treatment strategies in the context of a multidisciplinary package.

Emotion regulation and brain plasticity: expressive suppression use predicts anterior insula volume

Expressive suppression is an emotion regulation strategy that requires interoceptive and emotional awareness. These processes both recruit the anterior insula. It is not known, however, whether increased use of expressive suppression is associated with increased anterior insula volume. In the present study, high-resolution anatomical MRI images were used to calculate insula volumes in a set of 50 healthy female subjects (mean 21.9 years) using both region of interest (ROI) and voxel-based morphometry (VBM) approaches. Participants also completed trait measures of expressive suppression usage, cognitive reappraisal usage, and negative emotional reactivity (the latter two served as control measures). As predicted, both ROI and VBM methods found that expressive suppression usage, but not negative affect and cognitive reappraisal, was positively related to anterior insula volume. These findings are consistent with the idea that trait patterns of emotion processing are related to brain structure.

When pain and hunger collide; psychological influences on differences in brain activity during physiological and non-physiological gastric distension

Functional neuroimaging has been used extensively in conjunction with gastric balloon distension in an attempt to unravel the relationship between the brain, regulation of hunger, satiety, and food intake tolerance. A number of researchers have also adopted a more physiological approach using intra-gastric administration of a liquid meal which has revealed different brain responses to gastric balloon distension. These differences are important as they question the utility and relevance of non-physiological models such as gastric balloon distension, especially when investigating mechanisms of feeding behavior such as satiety. However, an assessment of the relevance of physiological versus non-physiological gastric distension has been problematic due to differences in distension volumes between studies. In this issue of Neurogastroenterology and Motility, Geeraerts et al. compare brain activity during volume matched nutrient gastric distension and balloon distension in healthy volunteers. Gastric balloon distension activated the 'visceral pain neuromatrix'. This network of brain regions was deactivated during nutrient infusion, supporting the notion that brain activity during physiological versus non-physiological distension is indeed different. The authors suggest deactivation of the pain neuromatrix during nutrient infusion serves as a prerequisite for tolerance of normal meal volumes in health.

Understanding gut-brain interactions in gastrointestinal pain by neuroimaging: lessons from somatic pain studies

BACKGROUND

Neuroimaging research on gut-brain interactions has greatly improved our understanding of the brain mechanisms involved in processing and perceiving visceral pain in health and functional gastrointestinal disorders (FGID). However, discrepancies in the results of these studies continue to exist, which is at least partially due to the fact that important factors contributing to the intrinsic heterogeneity of symptom-based FGID, including psychological processes and psychiatric comorbidity, are insufficiently integrated in visceral pain neuroimaging research.

PURPOSE

This review will defend the thesis that, to increase our understanding of the heterogeneous etiopathogenesis of FGID, visceral pain neuroimaging studies need to be integrated with: (i) epidemiological and behavioral evidence on the influence of psychological processes on visceral pain in health and FGID, and (ii) methodology and evidence from affective, cognitive, and psychiatric neuroimaging studies. To illustrate this point, the somatic pain neuroimaging field will be taken as an example before giving an overview of novel and integrative visceral pain studies in health and FGID. Some limitations of current pain neuroimaging studies will be outlined, before providing a summary of suggestions for moving the visceral pain neuroimaging field forward.