The effect of psychological stress and relaxation on interoceptive accuracy: Implications for symptom perception

Insula-cortico-subcortical networks predict interoceptive awareness and stress resilience

BACKGROUND

Interoception, the neural sensing of visceral signals, and interoceptive awareness (IA), the conscious perception of interoception, are crucial for life survival functions and mental health. Resilience, the capacity to overcome adversity, has been associated with reduced interoceptive disturbances. Here, we sought evidence for our Insula Modular Active Control (IMAC) model that suggest that the insula, a brain region specialized in the processing of interoceptive information, realizes IA and contributes to resilience and mental health via cortico-subcortical connections.

METHODS

64 healthy participants (32 females; ages 18-34 years) answered questionnaires that assess IA and resilience. Mental health was evaluated with the Beck Depression Inventory II that assesses depressive mood. Participants also underwent a 15 minute resting-state functional resonance imaging session. Pearson correlations and mediation analyses were used to investigate the relationship between IA and resilience and their contributions to depressive mood. We then performed insula seed-based functional connectivity analyzes to identify insula networks involved in IA, resilience and depressive mood.

RESULTS

We first demonstrated that resilience mediates the relationship between IA and depressive mood. Second, shared and distinct intra-insula, insula-cortical and insula-subcortical networks were associated with IA, resilience and also predicted the degree of experienced depressive mood. Third, while resilience was associated with stronger insula-precuneus, insula-cerebellum and insula-prefrontal networks, IA was linked with stronger intra-insula, insula-striatum and insula-motor networks.

CONCLUSIONS

Our findings help understand the roles of insula-cortico-subcortical networks in IA and resilience. These results also highlight the potential use of insula networks as biomarkers for depression prediction.

An Overview of the Bodily Awareness Representation and Interoception: Insights and Progress in the Field of Neurorehabilitation Research

In the last two decades, the scientific literature on so-called body representations has been increasing, and the notion of body awareness (BA) is particularly interesting for neurorehabilitation. In this article, we present results derived from recent studies on this representation, considering the different definitions and explicative models proposed as well as the empirical settings used to test it, providing an extensive overview of these issues. This article discusses the challenge of understanding how we integrate the sensory experiences of proprioception (knowing where our body is in space) and interoception (sensing internal bodily sensations, like hunger of thirst) with our perception of self. This is a difficult problem to analyze because our awareness of our body is inherently linked to our perspective, since the body is the means through which we interact with the world. Presenting the different viewpoints offered by recent theories on this concern, we highlighted that the neurorehabilitation and psychiatric settings offer two important fields useful for the study of BA because in them it is possible to analyze bodily representations by inducing/observing a controlled discrepancy between dysfunctional content and sensory inputs.

Vague sensations. About the background and consequences of discordance between actual and perceived physiological changes

Empirical evidence consistently shows that discordance, also called dissociation or discrepancy, between actual physiological (mainly visceral) events and their perceived counterparts is substantial. On the one hand, we typically do not perceive actual visceral events occurring in our bodies; on the other hand, sometimes we do perceive bodily changes that do not really take place. This narrative review presents the available empirical findings on the discordance, and summarizes possible explanations that approach the phenomenon from the viewpoint of evolution, cognitive development, and predictive processing. Also, the role of top-down factors, such as expectations and experiences is discussed. Finally, practically relevant consequences of the discordance are presented using the examples of mind-body practices, the placebo and nocebo phenomenon, and medically unexplained symptoms. It is concluded that the discordance between actual and perceived body changes can have a negative impact on health, mainly through issues with adherence and other behavioral factors. The existence of actual-perceived discordance should be taught and demonstrated in the elementary and high school, as well as in many areas of higher education.

Acute stress affects peripersonal space representation in cortisol stress responders

Peripersonal space is the representation of the space near the body. It is implemented by a dedicated multisensory-motor network, whose purpose is to predict and plan interactions with the environment, and which can vary depending on environmental circumstances. Here, we investigated the effect on the PPS representation of an experimentally induced stress response and compared it to a control, non-stressful, manipulation. We assessed PPS representation in healthy humans, before and after a stressful manipulation, by quantifying visuotactile interactions as a function of the distance from the body, while monitoring salivary cortisol concentration. While PPS representation was not significantly different between the control and experimental group, a relation between cortisol response and changes in PPS emerged within the experimental group. Participants who showed a cortisol stress response presented enhanced visuotactile integration for stimuli close to the body and reduced for far stimuli. Conversely, individuals with a less pronounced cortisol response showed a reduced difference in visuotactile integration between the near and the far space. In our interpretation, physiological stress resulted in a freezing-like response, where multisensory-motor resources are allocated only to the area immediately surrounding the body.

Alexithymia and intolerance of uncertainty predict somatic symptoms in autistic and non-autistic adults

LAY ABSTRACT

Autistic people have more physical health problems than non-autistic people. We were interested in whether autistic people experience more discomfort in their bodies than non-autistic people and whether certain psychological traits contribute to that. A survey was completed online by older adolescents and adults, 51 of whom were autistic, 32 of whom thought they might be autistic but were not diagnosed and 119 who were not autistic. They completed measures of somatic symptoms (daily experience of pain, discomfort, dizziness), alexithymia (difficulty identifying and expressing feelings), interoception (how much people are aware of their bodies) and intolerance of uncertainty (how people handle doubt or uncertainty), and reported any physical or mental health conditions. We found that the autistic participants had more physical and mental health conditions than the non-autistic participants, but even when we took account of this, they experienced higher levels of somatic symptoms. We looked at which psychological factors influenced levels of somatic symptoms across the whole sample, and found that alexithymia, intolerance of uncertainty, having physical health problems, being female and the number of mental health conditions predicted somatic symptoms, while interoception and autism diagnosis did not. The findings suggest that people may be more likely to experience physical discomfort if they are female, and have difficulty identifying and expressing feeling and difficulty tolerating doubt. As these psychological factors are more prominent in autism, we think this is important for physical and mental health providers to know about, so that these psychological factors can be considered when assessing and treating autistic people.

Interoception as independent cardiac, thermosensory, nociceptive, and affective touch perceptual submodalities

Interoception includes signals from inner organs and thin afferents in the skin, providing information about the body's physiological state. However, the functional relationships between interoceptive submodalities are unclear, and thermosensation as skin-based interoception has rarely been considered. We used five tasks to examine the relationships among cardiac awareness, thermosensation, affective touch, and nociception. Thermosensation was probed with a classic temperature detection task and the new dynamic thermal matching task, where participants matched perceived moving thermal stimuli in a range of colder/warmer stimuli around thermoneutrality. We also examined differences between hairy and non-hairy skin and found superior perception of dynamic temperature and static cooling on hairy skin. Notably, no significant correlations were observed across interoceptive submodality accuracies (except for cold and pain perception in the palm), which indicates that interoception at perceptual levels should be conceptualised as a set of relatively independent processes and abilities rather than a single construct. DATA AVAILABILITY STATEMENT: Data of this study are available as a supplementary file.

The Effects of a 3-Week Heartbeat Perception Training on Interoceptive Abilities

Recent studies showed promising short-term effects of heartbeat perception training on interoceptive abilities. Research on the effects of heartbeat perception training on interoceptive abilities over time is sparse. Therefore, the aim of this study was to examine the short-term effects and the effects of a 3-week heartbeat perception training over time on interoceptive abilities, namely, cardiac interoceptive accuracy (IAc) and interoceptive sensibility (IS). A total of 40 healthy participants were randomized to the intervention group (n = 20) or the control group (n = 20). The intervention group conducted three cardiac biofeedback sessions (one per week) at the laboratory, whereas the control group watched a documentary instead. Interoceptive abilities were assessed via the heartbeat perception task (IAc) and confidence ratings (IS) at baseline, after each laboratory session, and 1 week after the last session (post-measurement). IAc was significantly increased in the intervention group compared to the control group after the first training session (short-term effect). There were no significant improvements in IS due to the first session, and neither on IAc nor IS over time. Descriptive trends of improved interoceptive abilities over time were found in both groups. Single session of heartbeat perception training seems to be a promising approach to improve IAc. Future research should further investigate the long-term effects of diverse heartbeat perception training varying in frequency and intensity of the training sessions in diverse samples aiming to improve interoceptive abilities.

Traits and Distorted Symptom Presentation: a Scoping Review

Are personality traits related to symptom overreporting and/or symptom underreporting? With this question in mind, we evaluated studies from 1979 to 2020 (k = 55), in which personality traits were linked to scores on stand-alone validity tests, including symptom validity tests (SVTs) and measures of socially desirable responding (SDR) and/or supernormality. As to symptom overreporting (k = 14), associations with depression, alexithymia, apathy, dissociation, and fantasy proneness varied widely from weak to strong (rs .27 to .79). For underreporting (k = 41), inconsistent links (rs − .43 to .63) were found with narcissism, whereas alexithymia and dissociation were often associated with lower SDR tendencies, although effect sizes were small. Taken together, the extant literature mainly consists of cross-sectional studies on single traits and contexts, mostly offering weak correlations that do not necessarily reflect causation. What this field lacks is an overarching theory relating traits to symptom reporting. Longitudinal studies involving a broad range of traits, samples, and incentives would be informative. Until such studies have been done, traits are best viewed as modest concomitants of symptom distortion.

Where is emotional feeling felt in the body? An integrative review

Contemporary research on "embodied emotion" emphasizes the role of the body in emotional feeling. The evidence base on interoception, arguably the most prominent strand of embodied emotion research, places emphasis on the cardiac, respiratory and gastrointestinal systems. In turn, interoception has evidence-based links with improved emotion regulation. Despite the focus on separate bodily systems, it is unclear whether particular interoceptive locations play a greater role in emotional feeling and emotion regulation. Further, according to Gross' "process model", the sooner that regulation of an emotion occurs, the better; hence, it is additionally important to identify the first body areas to activate. These issues are investigated in a two-stage integrative review. The first stage was preliminary, giving an overview of the evidence base to highlight the distribution of measured body areas. This indicated that 86% of publications (n = 88) measured cardiac activity, 26% measured the respiratory system, and six percent the gastrointestinal system. Given the emphasis placed on all three systems in interoception theory and research on emotion, this suggests a dearth of comprehensive findings pertaining to feeling locations. The second stage investigated the core issues of where emotional feelings are felt in the body and time-related implications for regulation. This was based on ten texts, which together suggested that the head, throat and chest are the most consistently detected locations across and within numerous emotional contexts. Caution is required, however, since-among other reasons discussed-measurement was not time-restricted in these latter publications, and direct physiological measurement was found in only a minority of cases.

Effects of a Single Yoga Session on Cardiac Interoceptive Accuracy and Emotional Experience

BACKGROUND

There is an increasing body of research supporting the idea that cardiac interoceptive accuracy (IAc) can be improved by training. Findings concerning the effects of a single yoga session on IAc and the related construct emotional experience are sparse. The aim of this study was to examine if a single yoga session increases IAc and improves emotional experience.

METHODS

137 students were randomly assigned to a 20-min yoga session (n = 47), an endurance session (n = 46), or an inactive control condition (n = 44). IAc and emotional experience were assessed before and after the sessions.

RESULTS

There were no significant changes in IAc, or positive and negative affect. IAc at baseline and the change in positive effect were found as predictors for IAc after the yoga session.

CONCLUSION

A 20-min yoga session seems to be not applicable to improve IAc and emotional experience. Future studies should investigate long-term interventions and diverse healthy and clinical populations.

Different psychophysiological and clinical symptoms are linked to affective versus sensory vicarious pain experiences

For some people, seeing pain in others triggers a pain-like experience in themselves: these experiences can either be described in sensory terms and localized to specific body parts (sensory-localized, or S/L) or in affective terms and nonlocalized or whole-body experiences (affective-general, or A/G). In two studies, it is shown that these are linked to different clinical and psychophysiological profiles relative to controls. Study 1 shows that the A/G profile is linked to symptoms of Blood-Injection-Injury Phobia whereas the S/L profile shows some tendency toward eating disorders. Study 2 shows that the A/G profile is linked to poor interoceptive accuracy (for heartbeat detection) whereas the S/L profile is linked to higher heart-rate variability (HRV) when observing pain, which is typically regarded as an index of good autonomic emotion regulation. Neither group showed significant differences in overall heart rate, systolic blood pressure (SBP), or skin conductance response (SCR) when observing pain, and no overall differences in state or trait anxiety. Overall, the research points to different underlying mechanisms linked to different manifestations of vicarious pain response. Affective-General pain responders have strong subjective bodily experiences (likely of central origin given the absence of major differences in autonomic responsiveness) coupled with a worse ability to read objective interoceptive signals. Sensory-localized pain responders have differences in their ability to construct a multi-sensory body schema (as evidenced by prior research on the Rubber Hand Illusion) coupled with enhanced cardiovagal (parasympathetic) reactivity often indicative of better stress adaptation.

Interoception and stress in patients with Functional Neurological Symptom Disorder

INTRODUCTION

Research suggests that patients with Functional Neurological Symptom Disorder (pwFND) struggle to identify their own emotions and associated physiological cues (interoceptive sensitivity, IS). However, it is not known how this deficit interacts with stress. This study aimed to assess IS in pwFND at baseline and following stress induction, and relate the findings to self-reported emotion processing difficulties.

METHODS

Twenty-six pwFND and 27 healthy controls performed the Heart Beat Detection Task pre- and post-stress induction with the Cold Pressor Test. Participants also completed questionnaires assessing anxiety (GAD-7) and depressive symptomology (PHQ-9), as well as emotion processing (EPS-25).

RESULTS

Patients reported deficits in emotion processing (p < . 001) and had lower IS (p = .032) than healthy controls. IS improved following stress induction across both groups (p = .003) but patients' IS was lower than that of healthy controls' pre-and post-stress induction. Exploratory analyses revealed that patients reporting sensory symptoms had lower IS at baseline than patients who did not.

CONCLUSION

Our findings suggest that pwFND are relatively impaired in the identification of their emotions at baseline and following stress induction. This may be related to the experience of functional sensory symptoms and has implications for the psychological treatment of emotion dysregulation in this population.

Cardiac and Proprioceptive Accuracy Are Not Related to Body Awareness, Perceived Body Competence, and Affect

Interoception in the broader sense refers to the perception of internal states, including the perception of the actual state of the internal organs (visceroception) and the motor system (proprioception). Dimensions of interoception include (1) interoceptive accuracy, i.e., the ability to sense internal changes assessed with behavioral tests, (2) confidence rating with respect to perceived performance in an actual behavioral test, and (3) interoceptive sensibility, i.e., the self-reported generalized ability to perceive body changes. The relationship between dimension of cardioceptive and proprioceptive modalities and their association with affect are scarcely studied. In the present study, undergraduate students (N = 105, 53 males, age: 21.0 ± 1.87 years) filled out questionnaires assessing positive and negative affect (Positive and Negative Affect Schedule), interoceptive sensibility (Body Awareness Questionnaire), and body competence (Body Competence Scale of the Body Consciousness Questionnaire). Following this, they completed a behavioral task assessing cardioceptive accuracy (the mental heartbeat tracking task by Schandry) and two tasks assessing proprioceptive accuracy with respect to the tension of arm flexor muscles (weight discrimination task) and the angular position of the elbow joint (joint position reproduction task). Confidence ratings were measured with visual analog scales after the tasks. With the exception of a weak association between cardioceptive accuracy and the respective confidence rating, no associations between and within modalities were found with respect to various dimensions of interoception. Further, the interoceptive dimensions were not associated with state and trait positive and negative affect and perceived body competence. In summary, interoceptive accuracy scores do not substantially contribute to conscious representations of cardioceptive and proprioceptive ability. Within our data, non-pathological affective states (PANAS) are not associated with the major dimensions of interoception for the cardiac and proprioceptive modalities.

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.

Interoception, Stress, and Physical Symptoms in Stress-Associated Diseases

Abstract. The brain and peripheral bodily organs continuously exchange information. Exemplary, interoception refers to the processing and perception of ascending information from the body to the brain. Stress responses involve a neurobehavioral cascade, which includes the activation of peripheral organs via neural and endocrine pathways and can thus be seen as an example for descending information on the brain-body axis. Hence, the interaction of interoception and stress represents bi-directional communication on the brain-body axis. The main hypothesis underlying this review is that the dysregulation of brain-body communication represents an important mechanism for the generation of physical symptoms in stress-related disorders. The aims of this review are, therefore, (1) to summarize current knowledge on acute stress effects on different stages of interoceptive signal processing, (2) to discuss possible patterns of abnormal brain-body communication (i.e., alterations in interoception and physiological stress axes activation) in mental disorders and chronic physical conditions, and (3) to consider possible approaches to modify interoception. Due to the regulatory feedback loops underlying brain-body communication, the modification of interoceptive processes (ascending signals) may, in turn, affect physiological stress axes activity (descending signals), and, ultimately, also physical symptoms.

Age-Related Effects on Interoceptive Accuracy, General Interoceptive Sensibility, and Specific Interoceptive Sensibility

Abstract. Background: The current research into interoception distinguishes between interoceptive accuracy (IAcc), the accurate detection of internal sensations (e.g., heartbeats) as measured by performance on objective IAcc tasks, and interoceptive sensibility (IS), the subjective belief concerning one’s own experience of internal sensations as measured either through self-report questionnaires or through one’s confidence in the accuracy during an IAcc task. Aims: As the two measures of IS, however, are usually uncorrelated and show differential relationships to IAcc, we suggest different types of IS, a general IS and a specific IS. Further, based on a growing body of research linking IAcc and IS to physical and mental diseases, the development of interoception across the adult lifespan is of importance. Methods: Using Structural Equation Modeling the present paper investigates the relationships among IAcc assessed by a heartbeat counting task, and the two proposed dimensions of IS in 138 participants ( Mage = 42.67, SDage = 18.77). Furthermore, we examine age-related differences in IAcc, as well as in general and specific IS. Results: In terms of the relationship between the three dimensions, general and specific IS were weakly correlated and exhibited different relationships to IAcc. Further, we found different age effects on the three interoceptive dimensions. Whereas IAcc decreased with age, specific IS tend to increase with age, and general IS remained unaffected by age. Conclusion: The findings provide further empirical support for a dissociation between general and specific IS and raised important questions concerning the relation between interoceptive accuracy and the emergence of physical diseases in older age.

A Pilot Study on the Effect of an Energy Drink on Interoception in High vs. Low Anxiety Sensitivity Individuals

Abstract. Background: The market for energy drinks has grown quickly over the past 20 years. While the physiological and psychological effects of different ingredients have been studied, the influence of energy drinks on interoceptive processes is unclear. Anxiety has been associated with amplified interoceptive functioning, suggesting potentially exaggerated reactions to energy drinks. Aims: Investigate the effect of energy drink consumption and anxiety sensitivity (AS) as well as their possible interactions on cardiorespiratory dimensions of interoception. Method: Thirty-nine healthy students consumed an energy drink via a placebo-controlled, counterbalanced, crossover design. Cardiac and respiratory interoceptive accuracy (IAcc), interoceptive sensibility (IS), and interoceptive evaluation (IE) were assessed. Heartbeat-evoked potentials (HEPs) were analyzed to evaluate neural processing of the heartbeat. Results: Consumption of one energy drink did not influence IAcc, IS, or IE. However, high AS subjects reported reduced interoceptive confidence after energy drink intake. While HEP amplitudes did not differ depending on the type of drink, high AS subjects showed reduced HEPs overall compared to low AS subjects. Heart rate was significantly lower following energy drink consumption as compared to the placebo condition. Limitations: The sample size was small, energy dosages low, and physiological parameters should be assessed in more detail. Conclusion: Energy drink consumption was associated with an interoceptive bias in high AS individuals suggesting possible interaction effects between changes in physical state, interoception, and anxiety.

Factor Structure and Psychometric Properties of the Body Perception Questionnaire-Short Form (BPQ-SF) Among Chinese College Students

Objective

Body perception, including body awareness and reactivity, is featured in a range of mental health conditions. However, research on Chinese questionnaires assessing body perception has been surprisingly absent. The present study aimed to investigate the factor structure and psychometric properties of the Body Perception Questionnaire–Short Form (BPQ-SF) among Chinese.

Methods

the current sample included 688 Chinese college students. Self-report scales were used to measure body perception, somatization, and depressive somatic and psychological symptoms.

Results

Confirmatory factor analysis supported a three-factor model of the BPQ-SF, involving body awareness, supradiaphragmatic reactivity, and subdiaphragmatic reactivity. Good internal consistency and test–retest reliability were observed. Convergent validity was established by significant correlations with scores of somatization and somatic symptoms of depression. Divergent validity was evidenced by non-significant association with ratings on psychological symptoms of depression. The very short form of the body awareness subscale of BPQ can be an alternative to the body awareness subscale when scale length is the priority.

Conclusion

The BPQ-SF possessed three latent factors and demonstrated good psychometric properties that can measure body perception among Chinese in a reliable and valid way.

Do interoceptive accuracy and interoceptive sensibility predict emotion regulation?

INTRODUCTION

Interoception refers to awareness, interpretation, and integration of sensations in the body. While interoceptive accuracy has long been regarded as a core component of emotional experience, less is known about the relationship of interoceptive accuracy and related facets of interoception to emotion regulation deficits. This study explores how interoceptive accuracy and interoceptive sensibility relate to emotion regulation in a non-clinical sample.

METHODS

Undergraduate participants completed a heartbeat perception task and the Multidimensional Assessment of Interoceptive Awareness (Noticing and Body Listening sub-scales), and rated their confidence in performance on the heartbeat perception task. Participants also completed self-report measures of emotional awareness and regulation (Profile of Emotional Competence, intrapersonal emotion identification and emotion regulation sub-scales), and rated their use of different coping strategies (Brief COPE).

RESULTS

Noticing predicted emotion identification, emotion regulation, and the use of adaptive but not maladaptive coping strategies. Heartbeat perception accuracy did not significantly contribute to the prediction of any outcome variables.

DISCUSSION

Future work is needed to extend these findings to clinical populations. The results from this study support the use of interoceptive training interventions to promote emotional wellbeing.

Direct gaze enhances interoceptive accuracy

Direct-gaze signals are known to modulate human cognition, including self-awareness. In the present study, we specifically focused on 'bodily' self-awareness and examined whether direct gaze would modulate one's interoceptive accuracy (IAcc)-the ability to accurately monitor internal bodily sensations. While viewing a photograph of a frontal face with a direct gaze, an averted face or a mere white cross as a baseline, participants were required to count their heartbeats without taking their pulse. The results showed higher IAcc in the direct-gaze condition than in the averted-face or baseline condition. This was particularly the case in participants with low IAcc at baseline, indicating that direct gaze enhanced the participants' IAcc. Importantly, their heart rate was not different while viewing the direct gaze and averted face, suggesting that sensitivity to interoceptive signals, rather than physiological arousal, is heightened by direct gaze. These findings demonstrate the role of social signals in our bodily interoceptive processing and support the notion of the social nature of self-awareness.

Transcutaneous vagus nerve stimulation improves interoceptive accuracy

How can interoceptive accuracy, i.e. the objective ability to identify interoceptive signals, be improved? In the present study, we investigated whether non-invasive stimulation of the auricular branch of the vagus nerve (taVNS) modulates cardiac interoceptive accuracy, interoceptive sensibility, i.e. confidence in the identification of bodily signals, and interoceptive awareness, i.e. the capacity to evaluate one's ability in the objective task. Using a single-blind within-subjects design we compared participants' performance on the heartbeat counting task and on the heartbeat discrimination task during active and sham taVNS stimulation. Results revealed improved accuracy during active taVNS on the heartbeat discrimination task but not on the heartbeat counting task. Participants were also more confident during active stimulation, but interoceptive awareness was not modulated by taVNS. These findings show that taVNS can modulate interoceptive processing and suggest its potential as a tool to investigate body-brain interactions.

Major Depressive Disorder Is Associated with Impaired Interoceptive Accuracy: A Systematic Review

Interoception is the sense of the physiological condition of the entire body. Impaired interoception has been associated with aberrant activity of the insula in major depressive disorder (MDD) during heartbeat perception tasks. Despite clinical relevance, studies investigating interoceptive impairments in MDD have never been reviewed systematically according to the guidelines of the PRISMA protocol, and therefore we collated studies that assessed accuracy in detecting heartbeat sensations (interoceptive accuracy, IAc) in MDD (databases: PubMed/Medline, PsycINFO, and PsycARTICLES). Out of 389 records, six studies met the inclusion criteria. The main findings suggest that (i) moderately depressed samples exhibit the largest interoceptive deficits as compared with healthy adults. (ii) difficulties in decision making and low affect intensity are correlated with low IAc, and (iii) IAc seems to normalize in severely depressed subjects. These associations may be confounded by sex, anxiety or panic disorder, and intake of selective serotonin reuptake inhibitors. Our findings have implications for the development of interoceptive treatments that might relieve MDD-related symptoms or prevent relapse in recurrent depression by targeting the interoceptive nervous system.

Interoceptive Accuracy in Youth with Tic Disorders: Exploring Links with Premonitory Urge, Anxiety and Quality of Life

Aberrant interoceptive accuracy could contribute to the co-occurrence of anxiety and premonitory urge in chronic tic disorders (CTD). If it can be manipulated through intervention, it would offer a transdiagnostic treatment target for tics and anxiety. Interoceptive accuracy was first assessed consistent with previous protocols and then re-assessed following an instruction attempting to experimentally enhance awareness. The CTD group demonstrated lower interoceptive accuracy than controls but, importantly, this group difference was no longer significant following instruction. In the CTD group, better interoceptive accuracy was associated with higher anxiety and lower quality of life, but not with premonitory urge. Aberrant interoceptive accuracy may represent an underlying trait in CTD that can be manipulated, and relates to anxiety and quality of life.

Disconnected - Impaired Interoceptive Accuracy and Its Association With Self-Perception and Cardiac Vagal Tone in Patients With Dissociative Disorder

Patients suffering from dissociative disorders are characterized by an avoidance of aversive stimuli. This includes the avoidance of emotions and, in particular, bodily perceptions. In the present pilot study, we explored the potential interoceptive accuracy deficit of patients suffering from dissociative disorders in a heartbeat detection task. Moreover, we investigated the impact of facial mirror-confrontation on interoceptive accuracy and the potential association between cardiac vagal tone derived from heart rate variability and interoceptive accuracy. Eighteen patients suffering from dissociative disorders and 18 healthy controls were assessed with the Mental Tracking Paradigm by Schandry for heartbeat detection at baseline and after confrontations exposing them to their own faces in a mirror (2 min each, accompanied by a negative or positive cognition). During the experiment, cardiac vagal tone was assessed. We used Pearson correlations to calculate potential associations between cardiac vagal tone and interoceptive accuracy. Patients performed significantly worse than the healthy controls in the heartbeat detection task at baseline. They displayed no significant increase in interoceptive accuracy following facial mirror-confrontation. In the patient group, higher cardiac vagal tone was associated with a more precise heartbeat detection performance. Dissociative disorder patients showed a considerable deficit in interoceptive accuracy. Our results fit with the assumption that highly dissociative patients tend to tune out the perceiving of bodily signals. To the extent that bodily signal perception may play a causal role in these disorders, therapeutic approaches enhancing interoceptive accuracy and cardiac vagal tone may be considered important and practicable steps to improve the therapy outcome of this patient group.

Behavioral Inhibition Underlies the Link Between Interoceptive Sensitivity and Anxiety-Related Temperamental Traits

Interoceptive sensitivity (IS) is a biologically determined, constitutional trait of an individual. High IS has been often associated with proneness to anxiety. This association has been explained by elevated autonomic responsiveness in anxious individuals. However, in a heartbeat discrimination task (discrimination of heartbeats' simultaneity to an external stimulus) low cardiac responsiveness has accompanied enhanced performance. The relation between these factors seems task dependent, and cannot comprehensively explain the link between IS and anxiety. We explored for additional explanatory factors for this link. More specifically, we studied which anxiety-related temperamental traits most strongly predict IS in the discrimination task. Compatibly with earlier findings, IS was positively associated with individual trait anxiety and also other related traits such as negative affect, emotional intensity, and introversion. Interestingly, behavioral inhibition was the temperamental trait that most strongly predicted high IS, and, in fact, accounted for its significant associations with the other anxiety-related temperamental traits. Good performance on heartbeat discrimination task may reflect adaptive attentional control abilities in behaviorally inhibited individuals. These results can improve our understanding of how IS and other traits together determine the personality and wellbeing of a human individual.

Multilevel convergence of interoceptive impairments in hypertension: New evidence of disrupted body-brain interactions

Interoception, the sensing of visceral body signals, involves an interplay between neural and autonomic mechanisms. Clinical studies into this domain have focused on patients with neurological and psychiatric disorders, showing that damage to relevant brain mechanisms can variously alter interoceptive functions. However, the association between peripheral cardiac-system alterations and neurocognitive markers of interoception remains poorly understood. To bridge this gap, we examined multidimensional neural markers of interoception in patients with early stage of hypertensive disease (HTD) and healthy controls. Strategically, we recruited only HTD patients without cognitive impairment (as shown by neuropsychological tests), brain atrophy (as assessed with voxel-based morphometry), or white matter abnormalities (as evidenced by diffusion tensor imaging analysis). Interoceptive domains were assessed through (a) a behavioral heartbeat detection task; (b) measures of the heart-evoked potential (HEP), an electrophysiological cortical signature of attention to cardiac signals; and (c) neuroimaging recordings (MRI and fMRI) to evaluate anatomical and functional connectivity properties of key interoceptive regions (namely, the insula and the anterior cingulate cortex). Relative to controls, patients exhibited poorer interoceptive performance and reduced HEP modulations, alongside an abnormal association between interoceptive performance and both the volume and functional connectivity of the above regions. Such results suggest that peripheral cardiac-system impairments can be associated with abnormal behavioral and neurocognitive signatures of interoception. More generally, our findings indicate that interoceptive processes entail bidirectional influences between the cardiovascular and the central nervous systems.

A latent state-trait analysis of interoceptive accuracy

Interoceptive accuracy (IAc), that is, the ability to accurately perceive one's own bodily signals, is widely assumed to be a trait, although experimental manipulations such as stress may affect IAc. We used structural equation modeling to estimate the reliability of IAc, and the proportions of individual differences in IAc, explained by a trait and occasion-specific effects of situation and person-situation interactions. We assessed IAc in 59 healthy participants (40 women, M_Age  = 23.4 years) on three consecutive measurement occasions, approximately 1 week apart, in a rest and poststress condition, using a heartbeat counting and a heartbeat discrimination task. The results showed fair temporal stability (intraclass correlation coefficients ≥ 0.38) and good reliability (Mdn = .63; range .49-.83) for both methods. While around 40% of the variance of a single IAc measurement could be explained by a trait, approximately 27% was accounted for by occasion-specific effects of situation and person-situation interaction. These results suggest that IAc measures are relatively consistent and that situations and person-situation interactions impact IAc as measured at a certain point in time. An aggregation across at least two measurements is recommended when using IAc as a trait variable.

Autism spectrum disorder and interoception: Abnormalities in global integration?

Research over the past three decades has seen a revived interest in the way the human body—and the way in which it is perceived—interacts with aspects of our experience. Consequently, interoception (i.e. the perception of physiological feedback from the body) has recently been shown to be associated with a wide range of cognitive, emotional, and affective functions, making it broadly relevant to the study of autism spectrum disorder. Although limited qualitative accounts and empirical studies suggest that individuals with autism spectrum disorder encounter abnormalities when perceiving and integrating physiological feedback from their bodies, other studies have suggested that people with/without autism spectrum disorder do not differ in interoceptive ability after accounting for alexithymia. In this article, we discuss the newly recognized importance of interoception in autism spectrum disorder with a focus on how deficits in the perception of bodily feedback might relate to the core features and co-occuring psychopathology of autism spectrum disorder. Finally, a new integrated theory is advanced which posits that people with autism spectrum disorder may experience a reduced capacity to integrate interoceptive information that may result in a narrow attentional bodily focus and reduced motivational and behavioral drives.

Diminished Interoceptive Awareness in Fibromyalgia Syndrome

Sensitivity to signals arising within the body (interoceptive awareness) has been implicated in emotion processing; interindividual differences in interoceptive awareness modulate both subjective and physiological indicators of emotional experience and the regulation of emotion-related behaviors. This study investigated interoceptive awareness in patients with fibromyalgia syndrome (FMS), a chronic pain condition accompanied by various affective symptoms. Interoceptive awareness was assessed in 45 FMS patients and 31 healthy individuals using a heartbeat perception task. Cognitive performance, comorbid psychiatric disorders and medication use were assessed as possible confounding variables. Concerning the primary outcome, patients exhibited markedly reduced heartbeat perception compared to healthy individuals. Moreover, there was an inverse relationship between interoceptive awareness and FMS symptom severity. Reduced interoceptive awareness may be involved in the affective aspects of FMS pathology. Poor access to bodily signals may restrict patients´ ability to integrate these signals during emotional processing, which, by extension, may preclude optimal emotional self-regulation.

Symptoms and the body: Taking the inferential leap

The relationship between the conscious experience of physical symptoms and indicators of objective physiological dysfunction is highly variable and depends on characteristics of the person, the context and their interaction. This relationship often breaks down entirely in the case of "medically unexplained" or functional somatic symptoms, violating the basic assumption in medicine that physical symptoms have physiological causes. In this paper, we describe the prevailing theoretical approach to this problem and review the evidence pertaining to it. We then use the framework of predictive coding to propose a new and more comprehensive model of the body-symptom relationship that integrates existing concepts within a unifying framework that addresses many of the shortcomings of current theory. We describe the conditions under which a close correspondence between the experience of symptoms and objective physiology might be expected, and when they are likely to diverge. We conclude by exploring some theoretical and clinical implications of this new account.

Differentiating attention styles and regulatory aspects of self-reported interoceptive sensibility

Based on prior research, multiple discriminable dimensions of interoception have been defined: awareness, accuracy and sensibility. Some investigators defined interoceptive awareness as metacognitive awareness of interoceptive accuracy, assessed as correspondence between subjective confidence in and objective accuracy of one's heartbeat detection. However, metacognitive awareness has been understood quite differently: 'a cognitive set in which negative thoughts/feelings are experienced as mental events, rather than as the self' or as 'error awareness'. Interoceptive sensibility, defined as self-reported interoception, distinguishes self-reported interoception from objective interoceptive accuracy, but does not differentiate between anxiety-driven and mindful attention styles towards interoceptive cues, a distinction of key clinical importance: one attention style is associated with somatization and anxiety disorders; the other has been viewed as healthy, adaptive, resilience-enhancing. The self-report Multidimensional Assessment of Interoceptive Awareness was developed to differentiate these attention styles. It has been translated into 16 languages and applied in cross-sectional and longitudinal studies. Findings from these applications suggest that differentiating interoceptive sensibility according to attention style and regulatory aspects (i) provides insights into the psychology of interoceptive awareness, (ii) differentiates between clinically maladaptive and beneficial interoceptive attention, and (iii) helps elucidate therapeutic approaches that claim to provide health benefits by training mindful styles of bodily awareness.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Participants' above-chance recognition of own-heart sound combined with poor metacognitive awareness suggests implicit knowledge of own heart cardiodynamics

Mounting evidence suggests that interoceptive signals are fundamentally important for the experience of the self. Thus far, studies on interoception have mainly focused on the ability to monitor the timing of ongoing heartbeats and on how these influence emotional and self-related processes. However, cardiac afferent signalling is not confined to heartbeat timing and several other cardiac parameters characterize cardiodynamic functioning. Building on the fact that each heart has its own self-specific cardio-dynamics, which cannot be expressed uniquely by heart rate, we devised a novel task to test whether people could recognize the sound of their own heart even when perceived offline and thus not in synchrony with ongoing heartbeats. In a forced-choice paradigm, participants discriminated between sounds of their own heartbeat (previously recorded with a Doppler device) versus another person’s heart. Participants identified the sound of their own heart above chance, whereas their metacognition of performance – as calculated by contrasting performance against ratings of confidence - was considerably poorer. These results suggest an implicit access to fine-grained neural representations of elementary cardio-dynamic parameters beyond heartbeat timing.

Panic and comorbid depression and their associations with stress reactivity, interoceptive awareness and interoceptive accuracy of various bioparameters

BACKGROUND

While current theories on perception of interoceptive signals suggest impaired interoceptive processing in psychiatric disorders such as panic disorder or depression, heart-rate (HR) interoceptive accuracy (IAc) of panic patients under resting conditions is superior to that of healthy controls. Thus, in this study, we chose to assess further physiological parameters and comorbid depression in order to get information on how these potentially conflicting findings are linked together.

DESIGN

We used a quasi-experimental laboratory design which included multi-parametric physiological data collection of 40 panic subjects and 53 matched no-panic controls, as well as experimental induction of stress and relaxation over a time-course.

METHODS

Stress reactivity, interoceptive awareness (IAw; from the Body Perception Questionnaire (BPQ)) and IAc (as correlation between self-estimation and physiological data) were major outcome variables. Self-estimation of bioparametrical change was measured via numeric rating scales.

RESULT

Panic subjects had stronger HR-reaction and more accurate HR-interoception. Concurrently, though, their IAc of skin conductance level, pulse amplitude and breathing amplitude was significantly lower than that of the control group. Interestingly, comorbid depression was found to be associated with increased IAw but attenuated IAc.

LIMITATIONS

Demand characteristics and a categorical approach to panic confine the results.

CONCLUSION

The potentially conflicting findings coalesce, as panic was associated with an increase of the ability to perceive the fear-related parameter and a simultaneous decrease of the ability to perceive other parameters. The superordinate integration of afferent signals might be impaired.

Interoception and stress

Afferent neural signals are continuously transmitted from visceral organs to the brain. Interoception refers to the processing of visceral-afferent neural signals by the central nervous system, which can finally result in the conscious perception of bodily processes. Interoception can, therefore, be described as a prominent example of information processing on the ascending branch of the brain–body axis. Stress responses involve a complex neuro-behavioral cascade, which is elicited when the organism is confronted with a potentially harmful stimulus. As this stress cascade comprises a range of neural and endocrine pathways, stress can be conceptualized as a communication process on the descending branch of the brain–body axis. Interoception and stress are, therefore, associated via the bi-directional transmission of information on the brain–body axis. It could be argued that excessive and/or enduring activation (e.g., by acute or chronic stress) of neural circuits, which are responsible for successful communication on the brain–body axis, induces malfunction and dysregulation of these information processes. As a consequence, interoceptive signal processing may be altered, resulting in physical symptoms contributing to the development and/or maintenance of body-related mental disorders, which are associated with stress. In the current paper, we summarize findings on psychobiological processes underlying acute and chronic stress and their interaction with interoception. While focusing on the role of the physiological stress axes (hypothalamic-pituitary-adrenocortical axis and autonomic nervous system), psychological factors in acute and chronic stress are also discussed. We propose a positive feedback model involving stress (in particular early life or chronic stress, as well as major adverse events), the dysregulation of physiological stress axes, altered perception of bodily sensations, and the generation of physical symptoms, which may in turn facilitate stress.

Heartfelt empathy? No association between interoceptive awareness, questionnaire measures of empathy, reading the mind in the eyes task or the director task

Interoception, defined as afferent information arising from within the body, is the basis of all emotional experience and underpins the 'self.' However, people vary in the extent to which interoceptive signals reach awareness. This trait modulates both their experience of emotion and their ability to distinguish 'self' from 'other' in multisensory contexts. The experience of emotion and the degree of self/other distinction or overlap are similarly fundamental to empathy, which is an umbrella term comprising affect sharing, empathic concern and perspective-taking (PT). A link has therefore often been assumed between interoceptive awareness (IA) and empathy despite a lack of clear evidence. To test the hypothesis that individual differences in both traits should correlate, we measured IA in four experiments, using a well-validated heartbeat perception task, and compared this with scores on several tests that relate to various aspects of empathy. We firstly measured scores on the Index of Interpersonal Reactivity and secondly on the Questionnaire of Cognitive and Affective Empathy. Thirdly, because the 'simulationist' account assumes that affect sharing is involved in recognizing emotion, we employed the 'Reading the Mind in the Eyes Task' for the recognition of facial expressions. Contrary to expectation, we found no significant relationships between IA and any aspect of these measures. This striking lack of direct links has important consequences for hypotheses about the extent to which empathy is necessarily embodied. Finally, to assess cognitive PT ability, which specifically requires self/other distinction, we used the 'Director Task' but found no relationship. We conclude that the abilities that make up empathy are potentially related to IA in a variety of conflicting ways, such that a direct association between IA and various components of empathy has yet to be established.

The Contributions of Interoceptive Awareness to Cognitive and Affective Facets of Body Experience

Experience of one’s own body relies on signals arising within the body as well as on exteroceptive information, and on appraisal of cognitive and affective aspects of these signals. The present study investigated the impact of sensitivity to internal signals, that is, interoceptive awareness, on interindividual differences in cognitive and emotional aspects of body experience. Subjects with accurate (n = 30) versus poor (n = 30) interoceptive awareness, classified via a heartbeat perception task, completed the Body Consciousness Questionnaire and the Body Appraisal Inventory. Possible effects of emotional state on body experience were controlled for using measures of mood and anxiety. While the groups did not differ in their emotional state, individuals with accurate cardiac interoceptive awareness exhibited higher subjective sensitivity to bodily sensations and a more positive body image, characterized by stronger body-related self-confidence, greater satisfaction with physical appearance, greater perceived bodily self-control, as well as reduced hypochondriacal concerns, sexual discontent, and shame. The present findings extend earlier research on the importance of perception of physical cues for emotion, cognition, and behavior regulation. Our results underline the contribution of interoceptive information to body experience, where interindividual differences in the accessibility of such information modulate cognitive and affective facets of body image.

Cross-cultural differences in somatic awareness and interoceptive accuracy: a review of the literature and directions for future research

This review examines cross-cultural differences in interoception and the role of culturally bound epistemologies, historical traditions, and contemplative practices to assess four aspects of culture and interoception: (1) the extent to which members from Western and non-Western cultural groups exhibit differential levels of interoceptive accuracy and somatic awareness; (2) the mechanistic origins that can explain these cultural differences, (3) culturally bound behavioral practices that have been empirically shown to affect interoception, and (4) consequences for culturally bound psychopathologies. The following outlines the scope of the scientific review. Part 1 reviews studies on cultural variation in spontaneous somatic word use, linguistic expressions, traditional medical practices, and empirical laboratory studies to assess the evidence for cultural differences in somatic processes. Integration of these findings suggests a startling paradox: on the one hand, non-Western cultures consistently exhibit heightened somatic focus and awareness across a variety of contexts; on the other hand, non-Western cultures also exhibit less interoceptive accuracy in laboratory studies. Part 2 discusses the various mechanistic explanations that have been proposed to explain these cultural differences in somatic awareness and interoceptive accuracy, focusing on cultural schemas and epistemologies. Part 3 addresses the behavioral and contemplative practices that have been proposed as possible "interventions," or methods of cultivating bodily awareness and perceptual accuracy. Finally, Part 4 reviews the consequences of interoception for psychopathology, including somatization, body dysmorphia, eating disorders, and anxiety disorders.

Interoceptive sensitivity, body image dissatisfaction, and body awareness in healthy individuals

Relationships among interoceptive sensitivity (IS), body image dissatisfaction, body mass index (BMI), and self-reported body awareness were investigated in a cross-sectional study. Eighty-two Norwegian high school students and 70 Hungarian undergraduate university students participated in the study. Subjects completed two questionnaires (Body Image Ideals Questionnaire - BIQ; Body Awareness Questionnaire - BAQ) followed by the assessment of interoceptive sensitivity using the Mental Tracking Method (MTM). An inverse, medium-level relationship between body image dissatisfaction and IS was found in both the Norwegian and the Hungarian samples. The relationships between IS and self-reported body awareness, and between body image dissatisfaction and BMI were uniformly non-significant in both samples. Predictors of body image dissatisfaction were resting heart rate, gender, and IS in the regression analysis after controlling for BMI, age, and nationality. The negative relationship between IS and body image dissatisfaction described in patients with anorexia nervosa also exists in healthy individuals. There is no direct connection between IS and self-reported body awareness.