The role of mid-insula in the relationship between cardiac interoceptive attention and anxiety: evidence from an fMRI study

Heart rate and insula activity increase in response to music in individuals with high interoceptive sensitivity

Interoception plays an important role in emotion processing. However, the neurobiological substrates of the relationship between visceral responses and emotional experiences remain unclear. In the present study, we measured interoceptive sensitivity using the heartbeat discrimination task and investigated the effects of individual differences in interoceptive sensitivity on changes in pulse rate and insula activity in response to subjective emotional intensity. We found a positive correlation between heart rate and valence level when listening to music only in the high interoceptive sensitivity group. The valence level was also positively correlated with music-elicited anterior insula activity. Furthermore, a region of interest analysis of insula subregions revealed significant activity in the left dorsal dysgranular insula for individuals with high interoceptive sensitivity relative to individuals with low interoceptive sensitivity while listening to the high-valence music pieces. Our results suggest that individuals with high interoceptive sensitivity use their physiological responses to assess their emotional level when listening to music. In addition, insula activity may reflect the use of interoceptive signals to estimate emotions.

General and anxiety-linked influences of acute serotonin reuptake inhibition on neural responses associated with attended visceral sensation

Ordinary sensations from inside the body are important causes and consequences of our affective states and behaviour, yet the roles of neurotransmitters in interoceptive processing have been unclear. With a within-subjects design, this experiment tested the impacts of acute increases of endogenous extracellular serotonin on the neural processing of attended internal sensations and the links of these effects to anxiety using a selective serotonin reuptake inhibitor (SSRI) (20 mg CITALOPRAM) and a PLACEBO. Twenty-one healthy volunteers (fourteen female, mean age 23.9) completed the Visceral Interoceptive Attention (VIA) task while undergoing functional magnetic resonance imaging (fMRI) with each treatment. The VIA task required focused attention on the heart, stomach, or visual sensation. The relative neural interoceptive responses to heart sensation [heart minus visual attention] (heart-IR) and stomach sensation [stomach minus visual attention] (stomach-IR) were compared between treatments. Visual attention subtraction controlled for the general effects of CITALOPRAM on sensory processing. CITALOPRAM was associated with lower interoceptive processing in viscerosensory (the stomach-IR of bilateral posterior insular cortex) and integrative/affective (the stomach-IR and heart-IR of bilateral amygdala) components of interoceptive neural pathways. In anterior insular cortex, CITALOPRAM reductions of heart-IR depended on anxiety levels, removing a previously known association between anxiety and the region's response to attended heart sensation observed with PLACEBO. Preliminary post hoc analysis indicated that CITALOPRAM effects on the stomach-IR of the amygdalae corresponded to acute anxiety changes. This direct evidence of general and anxiety-linked serotonergic influence on neural interoceptive processes advances our understanding of interoception, its regulation, and anxiety.

The anterior cingulate cortex is involved in intero-exteroceptive integration for spatial image transformation of the self-body

Spatial image transformation of the self-body is a fundamental function of visual perspective-taking. Recent research underscores the significance of intero-exteroceptive information integration to construct representations of our embodied self. This raises the intriguing hypothesis that interoceptive processing might be involved in the spatial image transformation of the self-body. To test this hypothesis, the present study used functional magnetic resonance imaging to measure brain activity during an arm laterality judgment (ALJ) task. In this task, participants were tasked with discerning whether the outstretched arm of a human figure, viewed from the front or back, was the right or left hand. The reaction times for the ALJ task proved longer when the stimulus presented orientations of 0°, 90°, and 270° relative to the upright orientation, and when the front view was presented rather than the back view. Reflecting the increased reaction time, increased brain activity was manifested in a cluster centered on the dorsal anterior cingulate cortex (ACC), suggesting that the activation reflects the involvement of an embodied simulation in ALJ. Furthermore, this cluster of brain activity exhibited overlap with regions where the difference in activation between the front and back views positively correlated with the participants' interoceptive sensitivity, as assessed through the heartbeat discrimination task, within the pregenual ACC. These results suggest that the ACC plays an important role in integrating intero-exteroceptive cues to spatially transform the image of our self-body.

The insula: Leveraging cellular and systems-level research to better understand its roles in health and schizophrenia

Schizophrenia is a highly heterogeneous disorder characterized by a multitude of complex and seemingly non-overlapping symptoms. The insular cortex has gained increasing attention in neuroscience and psychiatry due to its involvement in a diverse range of fundamental human experiences and behaviors. This review article provides an overview of the insula's cellular and anatomical organization, functional and structural connectivity, and functional significance. Focusing on specific insula subregions and using knowledge gained from humans and preclinical studies of insular tracings in non-human primates, we review the literature and discuss the functional roles of each subregion, including in somatosensation, interoception, salience processing, emotional processing, and social cognition. Building from this foundation, we then extend these findings to discuss reported abnormalities of these functions in individuals with schizophrenia, implicating insular involvement in schizophrenia pathology. This review underscores the insula's vast role in the human experience and how abnormal insula structure and function could result in the wide-ranging symptoms observed in schizophrenia.

From synaptic dysfunction to atypical emotional processing in autism

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition mainly characterized by social impairments and repetitive behaviors. Among these core symptoms, a notable aspect of ASD is the presence of emotional complexities, including high rates of anxiety disorders. The inherent heterogeneity of ASD poses a unique challenge in understanding its etiological origins, yet the utilization of diverse animal models replicating ASD traits has enabled researchers to dissect the intricate relationship between autism and atypical emotional processing. In this review, we delve into the general findings about the neural circuits underpinning one of the most extensively researched and evolutionarily conserved emotional states: fear and anxiety. Additionally, we explore how distinct ASD animal models exhibit various anxiety phenotypes, making them a crucial tool for dissecting ASD's multifaceted nature. Overall, to a proper display of fear response, it is crucial to properly process and integrate sensorial and visceral cues to the fear-induced stimuli. ASD individuals exhibit altered sensory processing, possibly contributing to the emergence of atypical phobias, a prevailing anxiety disorder manifested in this population. Moreover, these individuals display distinctive alterations in a pivotal fear and anxiety processing hub, the amygdala. By examining the neurobiological mechanisms underlying fear and anxiety regulation, we can gain insights into the factors contributing to the distinctive emotional profile observed in individuals with ASD. Such insights hold the potential to pave the way for more targeted interventions and therapies that address the emotional challenges faced by individuals within the autism spectrum.

Subjective states induced by intracranial electrical stimulation matches the cytoarchitectonic organization of the human insula

Functions of the human insula have been explored extensively with neuroimaging methods and intracranial electrical stimulation studies that have highlighted a functional segregation across its subregions. A recently developed cytoarchitectonic map of the human insula has also segregated this brain region into various areas. Our knowledge of the functional organization of this brain region at the level of these fine-parceled microstructural areas remains only partially understood. We address this gap of knowledge by applying a multimodal approach linking direct electrical stimulation and task-evoked intracranial EEG recordings with microstructural subdivisions of the human insular cortex. In 17 neurosurgical patients with 142 implanted electrodes, stimulation of 40 % of the sites induced a reportable change in the conscious experience of the subjects in visceral/autonomic, anxiety, taste/olfactory, pain/temperature as well as somatosensory domains. These subjective responses showed a topographical allocation to microstructural areas defined by probabilistic cytoarchitectonic parcellation maps of the human insula. We found the pain and thermal responses to be located in areas lg2/ld2, while non-painful/non-thermal somatosensory responses corresponded to area ld3 and visceroceptive responses to area Id6. Lastly, the stimulation of area Id7 in the dorsal anterior insula, failed to induce reportable changes to subjective experience even though intracranial EEG recordings from this region captured significant time-locked high-frequency activity (HFA). Our results provide a multimodal map of functional subdivisions within the human insular cortex at the individual brain basis and characterize their anatomical association with fine-grained cytoarchitectonic parcellations of this brain structure.

Within-Person Modulation of Neural Networks following Interoceptive Awareness Training through Mindful Awareness in Body-Oriented Therapy (MABT): A Pilot Study

Interoception, the representation of the body's internal state, is increasingly recognized for informing subjective wellbeing and promoting regulatory behavior. However, few empirical reports characterize interoceptive neural networks, and fewer demonstrate changes to these networks in response to an efficacious intervention. Using a two-group randomized controlled trial, this pilot study explored within-participant neural plasticity in interoceptive networks following Mindful Awareness in Body-oriented Therapy (MABT). Participants (N = 22) were assigned to either 8 weeks of MABT or to a no-treatment control and completed baseline and post-intervention assessments that included subjective interoceptive awareness (MAIA) and neuroimaging of an interoceptive awareness task. MABT was uniquely associated with insula deactivation, increased functional connectivity between the dorsal attention network and the somatomotor cortex, and connectivity changes correlated positively with changes in subjective interoception. Within the MABT group, changes in subjective interoception interacted with changes in a predefined anterior cingulate seed region to predict changes in right middle insula activity, a putative primary interoceptive representation region. While the small sample size requires the replication of findings, results suggest that interoceptive training enhances sensory-prefrontal connectivity, and that such changes are commensurate with enhanced interoceptive awareness.

Insular dysfunction of interoception in major depressive disorder: from the perspective of neuroimaging

Interoception plays a crucial role in maintaining bodily homeostasis and promoting survival, and is considered the basis of human emotion, cognition, and self-formation. A malfunction of interoception is increasingly suggested to be a fundamental component of different mental health conditions, and depressive disorders have been especially closely associated. Interoceptive signaling and processing depends on a system called the "interoceptive pathway," with the insula, located in the deep part of the lateral fissure, being the most important brain structure in this pathway. Neuroimaging studies have revealed alterations in the structure and function of the insula in a large number of individuals with depression, yet the precise relationship between these alterations and interoceptive dysfunction remains unclear. The goal of this review is to examine the evidence that exists for dysfunction of interoception in people with Major Depressive Disorder (MDD), and to determine the associated specific alterations in the structure and function of the insula revealed by neuroimaging. Overall, three aspects of the potential relationship between interoceptive dysfunction and alterations in insular function in people with depression have been assessed, namely clinical symptoms, quantitative measures of interoceptive function and ability, and interoceptive modulation. To conclude, several specific limitations of the published studies and important lines of enquiry for future research are offered.

Interoceptive Awareness of the Breath Preserves Attention and Language Networks amidst Widespread Cortical Deactivation: A Within-Participant Neuroimaging Study

Interoception, the representation of the body's internal state, serves as a foundation for emotion, motivation, and wellbeing. Yet despite its centrality in human experience, the neural mechanisms of interoceptive attention are poorly understood. The Interoceptive/Exteroceptive Attention Task (IEAT) is a novel neuroimaging paradigm that compares behavioral tracking of the respiratory cycle (Active Interoception) to tracking of a visual stimulus (Active Exteroception). Twenty-two healthy participants completed the IEAT during two separate scanning sessions (N = 44) as part of a randomized control trial of mindful awareness in body-oriented therapy (MABT). Compared with Active Exteroception, Active Interoception deactivated somatomotor and prefrontal regions. Greater self-reported interoceptive sensibility (MAIA scale) predicted sparing from deactivation within the anterior cingulate cortex (ACC) and left-lateralized language regions. The right insula, typically described as a primary interoceptive cortex, was only specifically implicated by its deactivation during an exogenously paced respiration condition (Active Matching) relative to self-paced Active Interoception. Psychophysiological interaction (PPI) analysis characterized Active Interoception as promoting greater ACC connectivity with lateral prefrontal and parietal regions commonly referred to as the dorsal attention network (DAN). In contrast to evidence relating accurate detection of liminal interoceptive signals such as the heartbeat to anterior insula activity, interoceptive attention toward salient signals such as the respiratory cycle may involve reduced cortical activity but greater ACC-DAN connectivity, with greater sensibility linked to reduced deactivation within the ACC and language-processing regions.

Impact of climate change on wheat grain composition and quality

Wheat grain quality, an important determinant for human nutrition, is often overlooked when improving crop production for stressed environments. Climate change makes this task more difficult by imposing combined stresses. The scenarios relevant to climate change include elevated CO₂ concentrations (eCO₂ ) and extreme climatic events such as drought, heat waves, and salinity stresses. However, data on wheat quality in terms of climate change are limited, with no concerted efforts at the global level to provide an equitable and consistent climate risk assessment for wheat grain quality. Climate change induces changes in the quality and composition of wheat grain, a premier staple food crop globally. Climate-change events, such as eCO₂ , heat, drought, salinity stress stresses, heat + drought, eCO₂  + drought, and eCO₂  + heat stresses, alter wheat grain quality in terms of grain weight, nutrient, anti-nutrient, fiber, and protein content and composition, starch granules, and free amino acid composition. Interestingly, in comparison with other stresses, heat stress and drought stress increase phytate content, which restricts the bioavailability of essential mineral elements. All climatic events, except for eCO₂  + heat stress, increase grain gliadin content in different wheat varieties. However, grain quality components depend more on inter-varietal difference, stress type, and exposure time and intensity. The climatic events show differential regulation of protein and starch accumulation, and mineral metabolism in wheat grains. Rapid climate shifting impairs wheat productivity and causes grain quality to deteriorate by interrupting the allocation of essential nutrients and photoassimilates. © 2022 Society of Chemical Industry.

Real-world data of non-invasive stimulation of the human insula-prefrontal cortices using deep TMS to treat anxiety for occupational stress and generalized anxiety disorder

Activation of the insula is found in all anxiety-related disorders and increased insular-prefrontal cortex (PFC) functional connectivity is associated with reduced anxiety. In this study, the combined stimulation of the insula and PFC using the dTMS H4 (insula+LPFC) and H2 (PFC) coils were used to reduce anxiety in 13 subjects experiencing occupational stress, and 55 participants suffering from generalized anxiety disorder (GAD). The combined HF stimulation of the insula and PFC significantly decreased anxiety scores according to the HARS, CAS, and STAI anxiety scales, leading to a reduction in anxiety according to HARS of 88.7% and 70.7% in participants with occupational stress and the clinical sample of participants diagnosed with GAD, respectively. The findings suggest that the prefrontal-insular axis is critical for the regulation of anxiety and its stimulation can be used for the treatment of anxiety in people suffering from occupational stress and GAD.

Interoceptive attention facilitates emotion regulation strategy use

Background

Method

Results

Conclusions

Cardiac and Gastric Interoceptive Awareness Have Distinct Neural Substrates

Interoceptive awareness, an awareness of the internal body state, guides adaptive behavior by providing ongoing information on body signals, such as heart rate and energy status. However, it is still unclear how interoceptive awareness of different body organs are represented in the human brain. Hence, we directly compared the neural activations accompanying attention to cardiac (related to heartbeat) and gastric (related to stomach) sensations, which generate cardiac and gastric interoceptive awareness, in the same population (healthy humans, N = 31). Participants were asked to direct their attention toward heart and stomach sensations and become aware of them in a magnetic resonance imaging (MRI) scanner. The results indicated that the neural activations underlying gastric attention encompassed larger brain regions, including the occipitotemporal visual cortices, bilateral primary motor cortices, primary somatosensory cortex, left orbitofrontal cortex, and hippocampal regions. Cardiac attention, however, selectively activated the right anterior insula extending to the frontal operculum compared with gastric attention. Moreover, our detailed analyses focusing on the insula, the most relevant region for interoceptive awareness, revealed that the left dorsal middle insula encoded cardiac and gastric attention via different activation patterns, but the posterior insula did not. Our results demonstrate that cardiac and gastric attention evoke different brain activation patterns; in particular, the selective activation may reflect differences in the functional roles of cardiac and gastric interoceptive awareness.

Abnormal functional connectivity of brain regions associated with fear network model in panic disorder

Background: Patients with panic disorder (PD) have an abnormal function in brain regions related to fear network is well recognised. However, the traditional fear network model (FNM) which was based on animals' horrible behaviours has been found that it's not enough to explain the pathological mechanism of PD. This study aims to explore brain regions' abnormalities in the new advanced FNM, and estimate whether it can better explain PD.Methods: Magnetic resonance imaging resting-state scans were acquired in 40 patients with PD (35 drug-naïve and 5 drug-free) and 40 healthy controls (HCs). Twelve brain regions in the advanced FNM were chosen as regions of interest (ROIs) to examine the group difference in the ROIs and whole-brain resting-state functional connectivity (rsFC).Results: We found significantly increased thalamic rsFC with the insula, compared with HCs. And it was significantly correlated with HAMA-somatic score. We also found increased thalamic rsFC with occipital gyrus, temporal gyrus, and frontal gyrus when compared with HCs.Conclusions: Taken together, PD patients exhibit abnormal rsFC alterations within the advanced FNM, especially the increased rsFC within thalamus-insula loop, suggesting that excessive sensitivity to external information plays an important role in PD. The advanced FNM may provide a fuller explanation about PD.

Neural correlates associated with processing food stimuli in anorexia nervosa and bulimia nervosa: an activation likelihood estimation meta-analysis of fMRI studies

PURPOSE

Various neurobiological models have utilised symptom categories to explore the underlying neural correlates in both anorexia nervosa (AN) and bulimia nervosa (BN). The aim of this research was to investigate the brain activity patterns associated with viewing food stimuli in anorexia nervosa and bulimia nervosa.

METHODS

Electronic databases including PsycInfo and PubMed were systematically searched from data base inception until 1st of December 2020, identifying 14 suitable functional magnetic resonance imaging studies (fMRI), involving 470 participants. ALE meta-analysis was used to statistically analyse the overlap of activation foci from different fMRI studies in response to visual food stimuli.

RESULTS

Comparing patients with AN with healthy control (HC), we detected hypoactivation in brain areas related to reward processing (i.e., amygdala and lentiform nucleus), and interoceptive processing (i.e., insula). In addition, patients with AN showed hyperactivations in cognitive control areas (i.e., prefrontal and anterior cingulate cortex). In contrast, patients with BN exhibited hyperactivations in brain areas related to reward processing (i.e., lentiform nucleus), and interoceptive processing (i.e., insula). Furthermore, patients with BN showed hypoactivations in brain regions associated with cognitive control (i.e., prefrontal and anterior cingulate cortex).

CONCLUSIONS

Our study shows differing neural endotypes of the two types of eating disorders, that underpin their behavioural phenotypes. While exploratory in nature, these findings might be relevant for guiding new emerging therapies, including invasive and non-invasive neuromodulation techniques in treatment of eating disorders.

LEVEL OF EVIDENCE

Level I, meta-analysis.

A resting state fMRI study of major depressive disorder with and without anxiety

BACKGROUND

The neurobiology of the Major depressive disorder (MDD) with anxiety is still unclear. The present study aimed to explore the brain correlates of MDD with and without anxiety in men and women during resting-state fMRI.

METHODS

Two hundred and fifty-four patients with MDD (MDD with anxiety, N = 152) and MDD without anxiety, N = 102) and 228 healthy controls (HCs) participated in this study. We compared the fALFF(fractional amplitude of low-frequency fluctuations) and ReHo(regional homogeneity) of ACC(anterior cingulate cortex) and insula among these three groups. We also compared gender difference between MDD with anxiety and MDD without anxiety.

RESULTS

We found that the fALFF values within the ACC and insula were significantly lower in MDD with anxiety compared to without anxiety and HCs. However, we did not find differences in ReHo values among the three groups. In women, we found significant differences in fALFF values between MDD with and without anxiety. These differences were not observed in men.

CONCLUSIONS

It is possible that MDD with anxiety show less spontaneous BOLD-fMRI signal intensity within the ACC and insula compared to MDD without anxiety, especially in women. The fALFF within the ACC and insula can be a potential biomarker for severe MDD phenotype.

Misophonia: Analysis of the neuroanatomic patterns at the basis of psychiatric symptoms and changes of the orthosympathetic/ parasympathetic balance

Background/Aim

Misophonia is a disorder characterized by reduced tolerance to specific sounds or stimuli known as “triggers,” which tend to evoke negative emotional, physiological, and behavioral responses. In this study, we aimed to better characterize participants with misophonia through the evaluation of the response of the autonomic nervous system to “trigger sounds,” a psychometric assessment, and the analysis of the neurological pathways.

Materials and methods

Participants included 11 adults presenting with misophonic disturbance and 44 sex-matched healthy controls (HCs). Following recently proposed diagnostic criteria, the participants listened to six “trigger sounds” and a “general annoyance” sound (baby crying) during a series of physiological tests. The effects were examined through functional magnetic resonance imaging (fMRI), the analysis of heart rate variability (HRV), and of galvanic skin conductance (GSC). The fMRI was performed on a 3T Scanner. The HRV was obtained through the analysis of electrocardiogram, whereas the GSC was examined through the positioning of silver-chloride electrodes on fingers. Furthermore, the psychometric assessment included questionnaires focused on misophonia, psychopathology, resilience, anger, and motivation.

Results

Participants with misophonia showed patterns of increased sympathetic activation in response to trigger sounds and a general annoyance sound, the low frequency (LF) component of HRV, the sympathetic index, and the number of significant GSC over the threshold, where the amplitude/phasic response of GSC was higher. The fMRI analysis provided evidence for the activation of the temporal cortex, the limbic area, the ventromedial prefrontal/premotor/cingulate cortex, and the cerebellum in participants with misophonia. In addition, the psychometric assessment seemed to differentiate misophonia as a construct independent from general psychopathology.

Conclusion

These results suggest the activation of a specific auditory-insula-limbic pathway at the basis of the sympathetic activation observed in participants with misophonia in response to “trigger and general annoyance sounds.” Further studies should disentangle the complex issue of whether misophonia represents a new clinical disorder or a non-pathological condition. These results could help to build diagnostic tests to recognize and better classify this disorder. The relevance of this question goes beyond purely theoretical issues, as in the first case, participants with misophonia should receive a diagnosis and a targeted treatment, while in the second case, they should not.

Rhesus monkeys have an interoceptive sense of their beating hearts

SignificanceThe capacity to sense interoceptive signals is thought to be fundamental to broad functions including, but not limited to, homeostasis and the experience of the self. While neuroanatomical evidence suggests that nonhuman animals-namely, nonhuman primates-may possess features necessary for interoceptive processing in a way that is similar to humans, behavioral evidence of this capacity is slim. We presented macaques with audiovisual stimuli that were either synchronous or asynchronous with their heartbeat and demonstrated that they view asynchronous stimuli, whether faster or slower, for a significantly longer period than they do synchronous stimuli.

Mindfulness-Based Interventions for the Treatment of Aberrant Interoceptive Processing in Substance Use Disorders

Altered interoception, or the processing of bodily signals, has been argued to play a role in the development and maintenance of substance use disorders (SUD). Therefore, interoceptive interventions focusing on bodily awareness, such as mindfulness meditation, may improve treatment outcomes for individuals with SUD. Here we review: (1) subjective, behavioral and brain evidence for altered interoceptive processing in SUD, focusing on insular and anterior cingulate cortices (INS, ACC), key regions for interoceptive processing; (2) research highlighting links between mindfulness and brain function; and (3) extant brain research investigating mindfulness-based interventions in SUD. SUD tend to be characterized by heightened INS and ACC responses to drug cues but blunted interoceptive awareness and attenuated INS and ACC responses during tasks involving bodily attention and/or perturbations. In contrast, mindfulness interventions in healthy individuals are linked to enhanced INS and ACC responses and heightened interoceptive awareness. It is crucial for future research to identify: (1) whether mindfulness-based treatments are efficacious across substance classes; (2) what particular approaches and dosages show the largest effect sizes in enhancing INS and ACC function to non-drug stimuli and reducing responsivity to substance cues, thereby improving SUD treatment outcomes (reducing drug craving and relapse).

Interoception of breathing and its relationship with anxiety

Interoception, the perception of internal bodily states, is thought to be inextricably linked to affective qualities such as anxiety. Although interoception spans sensory to metacognitive processing, it is not clear whether anxiety is differentially related to these processing levels. Here we investigated this question in the domain of breathing, using computational modeling and high-field (7 T) fMRI to assess brain activity relating to dynamic changes in inspiratory resistance of varying predictability. Notably, the anterior insula was associated with both breathing-related prediction certainty and prediction errors, suggesting an important role in representing and updating models of the body. Individuals with low versus moderate anxiety traits showed differential anterior insula activity for prediction certainty. Multi-modal analyses of data from fMRI, computational assessments of breathing-related metacognition, and questionnaires demonstrated that anxiety-interoception links span all levels from perceptual sensitivity to metacognition, with strong effects seen at higher levels of interoceptive processes.

The paradoxical association between tension-reduction alcohol outcome expectancies and tension following alcohol consumption

BACKGROUND

Behavioral models suggest that strong tension-reduction alcohol-outcome expectancies (TREs) among drinkers should be associated with greater tension reduction after drinking. Yet, the few studies investigating this have found either no relationship or the opposite relationship.

OBJECTIVES

We sought to explore this relationship by building upon the limitations of past studies and employing a placebo-controlled, within-subject experimental design.

METHODS

Sixty social drinkers (26 M, 34 F) visited the lab on two occasions spaced one week apart. Each participant was randomly assigned to receive alcoholic drinks targeting a BAC of 0.05% on one testing day and placebo drinks on the other, with the order counter-balanced. On both testing days, participants completed measures of state anxiety and fear both before drinking and following a drinking/absorption period. While completing the self-report measures, participants were anticipating an impending, mildly stressful heartbeat perception task.

RESULTS

Multilevel modeling revealed that the more strongly individuals believed that alcohol reduces tension, the less the pharmacologic properties of alcohol did so (p = .02 for the state anxiety outcome measure; p = .001 for the fear outcome measure). This was the case even with anxiety sensitivity - a known predictor of stress-response dampening - controlled for.

CONCLUSIONS

These results provide further evidence for the paradoxical association of TREs and the dampening of anxiety. Additionally, the findings are consistent with the basis of expectancy challenges that aim to reframe inaccurate TREs among drinkers.

The Role of Interoceptive Attention and Appraisal in Interoceptive Regulation

Interoception, i.e., the processing and integration of sensory information has gained research interest due to its relevance in the psychopathological context. In the present review, we focus upon interoceptive regulation or one’s capacity to match bodily signals to his/her desired state by altering the signal or the desired state. More specifically, we discuss attention toward and appraisal of interoceptive stimuli as regulatory mechanisms of interoception. We review findings in the emerging research area of interoceptive attention. Studies suggest that the quality of attention and the nature of appraisal regarding interoceptive information influence interoceptive regulation and subsequent adaptive or maladaptive behavioral strategies among healthy controls as well as clinical populations. We discuss the clinical implications and the need to promote further research as well as to target interoceptive attention and appraisal mechanisms in psychotherapy.

Artificially altered gravity elicits cell homeostasis imbalance in planarian worms, and cerium oxide nanoparticles counteract this effect

Gravity alterations elicit complex and mostly detrimental effects on biological systems. Among these, a prominent role is occupied by oxidative stress, with consequences for tissue homeostasis and development. Studies in altered gravity are relevant for both Earth and space biomedicine, but their implementation using whole organisms is often troublesome. Here we utilize planarians, simple worm model for stem cell and regeneration biology, to characterize the pathogenic mechanisms brought by artificial gravity alterations. In particular, we provide a comprehensive evaluation of molecular responses in intact and regenerating specimens, and demonstrate a protective action from the space-apt for nanotechnological antioxidant cerium oxide nanoparticles.

Better living through understanding the insula: Why subregions can make all the difference

Insula function is considered critical for many motivated behaviors, with proposed functions ranging from attention, behavioral control, emotional regulation, goal-directed and aversion-resistant responding. Further, the insula is implicated in many neuropsychiatric conditions including substance abuse. More recently, multiple insula subregions have been distinguished based on anatomy, connectivity, and functional contributions. Generally, posterior insula is thought to encode more somatosensory inputs, which integrate with limbic/emotional information in middle insula, that in turn integrate with cognitive processes in anterior insula. Together, these regions provide rapid interoceptive information about the current or predicted situation, facilitating autonomic recruitment and quick, flexible action. Here, we seek to create a robust foundation from which to understand potential subregion differences, and provide direction for future studies. We address subregion differences across humans and rodents, so that the latter's mechanistic interventions can best mesh with clinical relevance of human conditions. We first consider the insula's suggested roles in humans, then compare subregional studies, and finally describe rodent work. One primary goal is to encourage precision in describing insula subregions, since imprecision (e.g. including both posterior and anterior studies when describing insula work) does a disservice to a larger understanding of insula contributions. Additionally, we note that specific task details can greatly impact recruitment of various subregions, requiring care and nuance in design and interpretation of studies. Nonetheless, the central ethological importance of the insula makes continued research to uncover mechanistic, mood, and behavioral contributions of paramount importance and interest. This article is part of the special Issue on 'Neurocircuitry Modulating Drug and Alcohol Abuse'.

The Relationship Between Functional Connectivity and Interoceptive Sensibility

Background: Interoceptive signals related to changes in heartbeat, respiration, and gastric functioning continuously feedback to the brain. The interpretation of these signals influences several cognitive, affective, and motoric functions. Previous research has highlighted the distinction between the ability to accurately detect interoceptive information (i.e., interoceptive accuracy) and an individual's beliefs about his or her interoceptive abilities (i.e., interoceptive sensibility). Although numerous studies have delineated the neural substrates of interoceptive accuracy, less is known about the brain areas involved with interoceptive sensibility. Materials and Methods: In the current study, 28 healthy participants completed the Multidimensional Assessment of Interoceptive Awareness (MAIA), a self-report measure of interoceptive sensibility, before undergoing a 7-min resting-state functional magnetic resonance imaging scan. IRB ethics approval was obtained prior to data collection. Results: Overall MAIA scores, as well as scores on its eight subscales, were entered as covariates in subsequent region-of-interest and independent-component analyses. These analyses yielded three key results. First, interoceptive sensibility was negatively correlated with the functional connectivity of visual regions. Second, the cerebellar resting-state network showed positive correlations with two MAIA subscales, suggesting that this structure plays a role in interoceptive functions. Finally, the functional connectivity of the insula, a structure critical for interoceptive accuracy, was not correlated with any of the MAIA scores. Conclusion: These results demonstrate that the brain areas associated with individual differences in interoceptive sensibility show relatively little overlap with those involved with the accurate detection of interoceptive information.

Increased attentional network activity in premature ejaculation patients with anxiety revealed by resting-state functional magnetic resonance imaging

Psychological account hypothesizes that premature ejaculation (PE) is a learned pattern of rapid ejaculation maintained by anxiety about sexual failure, whereas neuropsychological accounts hypothesizes that PE is the result of dysfunction of central nervous system regulating ejaculatory. However, the central neural mechanism underlying PE patients with anxiety remains unclear. Resting-state functional magnetic resonance imaging (fMRI) data were collected in 20 PE (diagnoses based on PE Guidelines drafted by the International Society for Sexual Medicine [ISSM]) patients with anxiety and 25 matched healthy controls (HCs) from January 2019 to December 2020. The values of fractional amplitude of low-frequency fluctuation (fALFF) were compared between groups. Moreover, the correlations between fALFF and the severity of PE and anxiety of patients were examined. PE patients with anxiety had increased fALFF values in the right inferior frontal gyrus (opercular part) and middle frontal gyrus. In addition, significant positive correlations were found between the scores of PE diagnostic tool (PEDT) and fALFF values of the right inferior frontal gyrus (opercular part), as well as the right middle frontal gyrus. Moreover, fALFF values of the right inferior frontal gyrus (opercular part) and middle frontal gyrus were positively correlated with the scores of self-rating anxiety scale (SAS). Our results suggested that increased attentional network activity might play a critical role in the neural basis of PE patients with anxiety.

Out-of-step: brain-heart desynchronization in anxiety disorders

Imaging studies in anxiety disorders (AD) show abnormal functional connectivity primarily in the salience network (SN), somatomotor network (SMN), and default mode network (DMN). However, it is not clear how precisely these network changes occur including their relation to psychopathological symptoms. Here, we show that the functional networks affected in AD overlap with cortical regions that receive visceral inputs (the so-called central/visceral autonomic network). Focusing on cardiac afferents, we suggest that network changes in AD may be due to reduced phase synchronization between ongoing neural and cardiac activity. This neuro-cardiac desynchronization occurs due to the abnormal phase resetting of neural activity at the onset of each heartbeat, as measured by a lower intertrial coherence and heartbeat-evoked potential. Biochemically, cardiac afferents reach subcortical serotonergic raphe nuclei and noradrenergic locus coeruleus (among others) which, in turn, are known to reciprocally modulate the DMN and SMN/SN on the cortical level. Consistent with the network changes in AD, decreases in serotonergic and noradrenergic activity are known to increase connectivity in both SMN and SN while, at the same time, they decrease DMN connectivity. SMN and SN increases, in turn, lead to increased emotional arousal/anxiety and bodily awareness whereas decreased DMN connectivity leads to an unstable sense-of-self in AD. Finally, we integrate our proposal with interoceptive predictive processing models suggesting neuro-cardiac desynchronization as a mechanism for "noisy" bottom-up information leading to a persistently uncertain bodily state in top-down models. In sum, integrating theories on active interference and hyperarousal, we propose a precise neuro-cardiac and biochemically -driven mechanisms for key psychopathological symptoms of AD.

Altered Task-Evoked Corticolimbic Responsivity in Generalized Anxiety Disorder

Generalized anxiety disorder (GAD) is marked by uncontrollable, persistent worry and exaggerated response to uncertainty. Here, we review and summarize the findings from the GAD literature that employs functional neuroimaging methods. In particular, the present review focuses on task-based blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies. We find that select brain regions often regarded as a part of a corticolimbic circuit (e.g., amygdala, anterior cingulate cortex, prefrontal cortex) are consistently targeted for a priori hypothesis-driven analyses, which, in turn, shows varying degrees of abnormal BOLD responsivity in GAD. Data-driven whole-brain analyses show the insula and the hippocampus, among other regions, to be affected by GAD, depending on the task used in each individual study. Overall, while the heterogeneity of the tasks and sample size limits the generalizability of the findings thus far, some promising convergence can be observed in the form of the altered BOLD responsivity of the corticolimbic circuitry in GAD.

Role of anatomical insular subdivisions in interoception: Interoceptive attention and accuracy have dissociable substrates

Prior neuroimaging studies have supported the idea that the human insular cortex plays an important role in processing and representing internal bodily states, also termed "interoception." According to recent theoretical studies, interoception includes several aspects such as attention and accuracy. However, there is no consensus on the laterality and location of the insula to support each aspect of interoception. Thus, we aimed to identify the anatomical insular subdivisions involved in interoceptive attention and accuracy; we examined 28 healthy volunteers who completed the behavioral heartbeat counting task and interoceptive attention paradigm using functional magnetic resonance imaging. First, interoceptive attention induced significant activation in the bilateral frontal operculum, precentral gyrus, middle insula, middle cingulate cortex, and supplementary motor area. Then, we compared the activation in anatomically predefined insular subdivisions during interoceptive attention. The highest activation of the middle short gyrus was noted within the insular cortex, followed by the anterior short gyrus and posterior short gyrus, while no significant hemispheric differences were observed. Finally, the interoceptive accuracy index, measured using the heartbeat counting task, strongly correlated with the activity of the right dorsal anterior insula/frontal operculum. These findings suggest that interoceptive attention is associated with the bilateral dorsal mid-anterior insula, which supports the processing and representation of bodily signals. In contrast, the more dorsal anterior portion of the right insula plays a key role in obtaining accurate interoception.

Intrinsic functional brain connectivity patterns underlying enhanced interoceptive sensibility

BACKGROUND

Cumulative evidence has suggested that brain regions including the bilateral insula and the anterior cingulate cortex play critical roles in the processing of interoceptive information. However, the brain functional connectivity patterns underlying interoceptive sensibility (IS) and their role in the relationship between IS and self-reported bodily symptoms remain unknown. We aimed to investigate the intrinsic functional connectivity patterns associated with IS and how this modulates the relationship between IS and self-reported bodily symptoms.

METHODS

Resting-state functional magnetic resonance imaging was used to test the intrinsic large-scale functional connectivity in 459 healthy subjects. IS and self-reported bodily symptoms were assessed by questionnaires.

RESULTS

Individuals with greater IS had a stronger tendency to report bodily symptoms. Higher IS was correlated with decreased ventral anterior insula-superior temporal gyrus, dorsal anterior cingulate cortex-middle frontal cortex and amygdala-medioventral occipital cortex connectivity. The large-scale functional connectivity of cingulo-opercular task control network (CON)-default mode network, CON-subcortical network and CON-dorsal attention network moderated the association between IS and bodily symptoms.

LIMITATIONS

The Body Perception Questionnaire mainly reflects the self-perceived tendency to focus on negatively-valenced interoceptive sensations. Future research should distinguish neutral and negative IS in order to make the definition of IS clearer.

CONCLUSIONS

This study suggests that IS may be related to impaired intrinsic functional connectivity between brain areas related to multisensory integration and cognitive-affective control, resulting in increased vigilance-attention to bodily signals. These findings offer new empirical evidence for a better understanding of the intricate relationships between interoception and symptom reporting.

Oxytocin Differentially Modulates Amygdala Responses during Top-Down and Bottom-Up Aversive Anticipation

The ability to successfully regulate negative emotions such as fear and anxiety is vital for mental health. Intranasal administration of the neuropeptide oxytocin (OXT) has been shown to reduce amygdala activity but to increase amygdala-prefrontal cortex connectivity during exposure to threatening stimuli suggesting that it may act as an important modulator of emotion regulation. The present randomized, between-subject, placebo-controlled pharmacological study combines the intranasal administration of OXT with functional magnetic resonance imaging (fMRI) during an explicit emotion regulation paradigm in 65 healthy male participants to investigate the modulatory effects of OXT on both bottom-up and top-down emotion regulation. OXT attenuates the activation in the posterior insular cortex and amygdala during anticipation of top-down regulation of predictable threat stimuli in participants with high trait anxiety. In contrast, OXT enhances amygdala activity during the bottom-up anticipation of unpredictable threat stimuli in participants with low trait anxiety. OXT may facilitate top-down goal-directed attention by attenuating amygdala activity in high anxiety individuals, while promoting bottom-up attention/vigilance to unexpected threats by enhancing amygdala activity in low anxiety individuals. OXT may thus have the potential to promote an adaptive balance between bottom-up and top-down attention systems depending on an individual's trait anxiety level.

Insula shows abnormal task-evoked and resting-state activity in first-episode drug-naïve generalized anxiety disorder

BACKGROUND

Interoception is associated with neural activity in the insula of healthy humans. On the basis of the somatic symptoms in generalized anxiety disorder (GAD), especially abnormal heartbeat perception, we hypothesized that abnormal activity in the insula was associated with interoceptive awareness in patients with GAD.

METHODS

We investigated the psychological correlates of interoceptive awareness in a sample of 34 patients with first-onset, drug-naïve GAD and 30 healthy controls (HCs). Furthermore, we compared blood oxygenation level-dependent responses between the two groups during a heartbeat perception task to assess task-evoked activity and its relationship with psychological measures. We also examined between-group differences in insular subregions resting-state functional connectivity (rsFC), and its relationship with anxiety severity.

RESULTS

Patients with GAD had significantly higher body perception scores than HCs. They also exhibited greater task-evoked activity in the left anterior insula, left posterior insula, and right anterior insula during interoceptive awareness than HCs. Left anterior insula activity was positively correlated with body awareness in patients with GAD, and rsFC between the left anterior insula and left medial prefrontal gyrus was negatively correlated with somatic anxiety severity.

CONCLUSIONS

Investigating a sample of first-episode, drug-naïve patients, our study demonstrated abnormal interoceptive awareness in patients with GAD and that this was related to abnormal anterior insular activity during both rest and task. These results shed new light on the psychological and neural substrates of somatic symptoms in GAD, and they may serve to establish abnormal interoceptive awareness as a neural and psychological marker of GAD.

Interoceptive accuracy and its impact on neuronal responses to olfactory stimulation in the insular cortex

The insular cortex plays a key role in the integration of multimodal information and in interoceptive and exteroceptive processing. For instance, neurons in the central dorsal insula that are active during interoceptive tasks, also show an adaptation to gustatory stimulation. We tested the link between interoception and exteroception for the olfactory system (i.e., the second domain of chemosensation). In a sample of 31 participants, olfactory function was assessed in a two dimensional approach while the Heartbeat Perception Task served as a measurement for cardiac interoceptive accuracy. Subsequent fMRI sessions were performed on a 3‐Tesla MR scanner containing 12–15 olfactory stimulation trials with a mildly pleasant food‐related odor (coffee). Persons scoring high in the cardiac interoceptive accuracy task presented stronger smelling abilities as well as enhanced BOLD responses following olfactory stimulation. The olfactory stimulation triggered enhanced insular activation patterns in the central dorsal insular cortex. Consistent with prior findings on the coherence of gustatory and interoceptive processing in the central dorsal insula, these results base the insula as a common region for the integration of interoception and exteroception. We propose an explanatory model of how exteroception triggers the integration of intero‐ and exteroceptive sensations in the central dorsal insular cortex.

A multidimensional and multi-feature framework for cardiac interoception

Interoception (the sensing of inner-body signals) is a multi-faceted construct with major relevance for basic and clinical neuroscience research. However, the neurocognitive signatures of this domain (cutting across behavioral, electrophysiological, and fMRI connectivity levels) are rarely reported in convergent or systematic fashion. Additionally, various controversies in the field might reflect the caveats of standard interoceptive accuracy (IA) indexes, mainly based on heartbeat detection (HBD) tasks. Here we profit from a novel IA index (md) to provide a convergent multidimensional and multi-feature approach to cardiac interoception. We found that outcomes from our IA-md index are associated with -and predicted by- canonical markers of interoception, including the hd-EEG-derived heart-evoked potential (HEP), fMRI functional connectivity within interoceptive hubs (insular, somatosensory, and frontal networks), and socio-emotional skills. Importantly, these associations proved more robust than those involving current IA indexes. Furthermore, this pattern of results persisted when taking into consideration confounding variables (gender, age, years of education, and executive functioning). This work has relevant theoretical and clinical implications concerning the characterization of cardiac interoception and its assessment in heterogeneous samples, such as those composed of neuropsychiatric patients.

Association of decrease in insula fMRI activation with changes in trait anxiety in patients with craniomandibular disorder (CMD)

Patients with chronic pain and especially with craniomandibular disorder (CMD) show specific psychopathology in trait anxiety. In a previous longitudinal functional imaging study on CMD we found that the anterior insula was modulated by successful therapy intervention and pain relief. We here intended to investigate possible associations between anterior insula fMRI-activation during occlusal movements and trait anxiety over a splint therapy approach in patients with CMD. Three fMRI-investigations of a craniomandibular occlusion task were performed together with pain score evaluations and scoring of trait anxiety (State -Trait Anxiety Inventory; STAI) before, after two weeks and after three months of a DIR-mandibular splint therapy in a small group (n = 9) of CMD patients. Patients showed increased anxiety levels before therapy assessed with the STAI and the depression and anxiety scale (DASS). Besides of relevant reduction in pain the STAI decreased over time. Reduction in STAI was associated with anterior insular fMRI-activation reduction on both hemispheres. We conclude that the anxiety driven anticipation of pain related to occlusal trigger is processed in the anterior insula and might therefore be a main driver of therapeutic intervention by the splint therapy in CMD.