Cold pressor stress induces opposite effects on cardioceptive accuracy dependent on assessment paradigm

Disrupted interoceptive awareness by auditory distractor: Difficulty inferring the internal bodily states?

Recent studies have associated interoceptive awareness, the perception of internal bodily sensations, with a predictive mechanism of perception across all sensory modalities. According to the framework, volitional attention plays a pivotal role in interoceptive awareness by prioritizing interoceptive sensations over exteroceptive ones. Consequently, it is hypothesized that the presence of irrelevant stimuli would disrupt the attentional modulation and interoceptive awareness, which remains untested. In this study, we investigated if interoceptive awareness is diminished by unrelated auditory distractors to validate the proposed perceptual framework. A total of 30 healthy human volunteers performed the heartbeat counting task both with and without auditory distractors. Additionally, we measured participant's psychophysiological traits related to interoception, including the high-frequency component of heart rate variability (HF-HRV) and trait interoceptive sensibility. The results showed that interoceptive accuracy, confidence, and heartbeat intensity decreased in the presence of distractor sound. Moreover, individuals with higher HF-HRV and a greater tendency to worry about bodily states experienced a more pronounced distractor effect on interoceptive awareness. These results provide support for the perceptual mechanism of interoceptive awareness in terms of the predictive process, highlighting the impact of relative precision across interoceptive and exteroceptive signals on perceptual experiences.

Heart rate perception and expectation impact laboratory-induced perceived stress

Previous studies have shown that the human capacity to gauge one's own physiological state is notoriously flawed. The cause for the mismatch between perceived and physiological stress has not yet been properly identified. In this study, we assumed that cardioceptive accuracy (CAc) is positively associated with cardiovascular reactivity, and CAc and expectation about stress might account for the discrepancy between perceived and physiological stress. In a crossover experiment, we assessed cardioceptive accuracy in two ways (mental heartbeat tracking task and perception of heart rate), and induced physiological (handgrip exercise) and mental (N-back task) stress in 64 university students (51 % male, mean age 22.2). We assessed cardiac and electrodermal activity, and expected and perceived stress. We found that indicators of cardioceptive accuracy were not associated with cardiovascular reactivity. However, heart rate perception moderated the association between the change in heart rate and perceived stress in the physical but not in the mental task. Whereas heartbeat tracking accuracy was not associated with perceived stress. Moreover, perceived stress was predicted by the expected stress but not by the change in heart rate and electrodermal activity in the mental stress task. In conclusion, heart rate perception and expectation of stress may shape perceived stress more than actual physiological changes in moderate acute stress.

Trauma, early life stress, and mindfulness in adulthood

This article is a review that was inspired by recent studies investigating the effects of childhood trauma or early life stress (ELS) and mindfulness in adulthood. One recent study found that some forms of abuse and neglect led to higher scores in several subscales of a self-report measure of mindfulness. The authors concluded that some forms of ELS can help cultivate certain aspects of mindfulness in adulthood. However, and in contrast to this recent finding, much of the extant literature investigating ELS and trauma are linked to emotional dysregulation, alexithymia, and a host of psychopathologies in adulthood which makes the results of this study surprising. Central to the mindfulness literature is cultivating an open, non-reactive, or non-judgment awareness of inner experiences which are important for emotional regulation. In this paper, I review some of the effects of trauma or ELS on critical neural circuits linked to mindfulness, interoception, attachment, and alexithymia which I hope may clarify some of the conflicting findings from this study and throughout the literature and provide additional context and a framework that may inform research investigating these two constructs going forward.

Interoception: Where do we go from here?

In recent years, there has been a significant rise in interest in interoception, the processing of internal bodily signals. This interest has been coupled by increased concerns regarding the measurement and conceptualisation of interoception. Focusing on cardiac interoceptive accuracy, I outline what I believe to be the most pressing issues in the field of interoception-specifically the continued reliance on the heartbeat counting task. I then provide an overview of what I believe to be more general limitations concerning how we measure and conceptualise individual differences in interoception and suggestions for a way forward. Specifically, I believe that by moving beyond single measurements, establishing optimal levels of interoceptive accuracy, and refocusing from accuracy to propensity, we may be able to uncover the real-life relevance of interoceptive abilities.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The impact of traumatic childhood experiences on interoception: disregarding one's own body

BACKGROUND

Deficient interoception, the processing and perception of internal bodily signals, has been discussed as a mechanism underlying various mental disorders. First results indicate a mediating role of interoception in the interplay of traumatic childhood experiences and adult mental disorders. Traumatic childhood experiences may hinder the adequate processing, integration, and trust in bodily signals that are important in order to understand and regulate own needs and emotions, thereby increasing the vulnerability for mental disorders. However, an overarching study investigating alterations in different interoceptive measures and trauma-related disorders as well as their mediating role between early trauma and emotion dysregulation is still missing.

METHODS

One hundred thirty-six individuals with varying levels of traumatic childhood experiences who either had a current diagnosis of major depression, posttraumatic stress disorder, or somatic symptom disorder, or no mental disorder, took part in a multidimensional assessment of interoceptive processes, including interoceptive accuracy, sensibility, and awareness. Kruskal-Wallis tests were used to compare groups regarding interoceptive processes and associations with traumatic childhood experiences and emotion dysregulation were analyzed with Spearman correlations. Furthermore, mediation analyses were computed to examine and compare interoceptive processes as potential mediators between traumatic childhood experiences and emotion dysregulation.

RESULTS

Only body dissociation, a measure for interoceptive sensibility, was significantly reduced in individuals with a current mental disorder. Body dissociation was also the only interoceptive measure significantly associated with traumatic childhood experiences and emotion dysregulation and the only significant mediator in the relationship between traumatic childhood experiences and emotion dysregulation across groups.

CONCLUSION

Results suggest body dissociation, but not other interoceptive measures, as an important feature linking traumatic childhood experiences to current emotion dysregulation, an important transdiagnostic feature. As body dissociation refers to a habitual non-attendance or disregard of interoceptive signals, integrative therapeutic interventions could help affected individuals to overcome difficulties in emotion perception and regulation.

TRIAL REGISTRATION

The general study design was preregistered; see the German Clinical Trials Register (DRKS-ID: DRKS00015182). This study's analysis plan was not preregistered.

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.

Dissociations between self-reported interoceptive accuracy and attention: evidence from the interoceptive attention scale

Models of interoception highlight the importance of considering participants' beliefs regarding their interoceptive ability. Research focusing on such beliefs suggests a dissociation between self-reported interoceptive accuracy and attention. However, it remains unclear whether such dissociations are driven by differences in the sensations rated across these questionnaires, or a genuine dissociation between different facets of self-reported interoception. Here we examined the relationship between self-report measures of interoceptive accuracy and attention using a novel measure- the Interoceptive Attention Scale- designed to match the interoceptive sensations included in an existing questionnaire measure of interoceptive accuracy. In addition, we examined whether the interpretation of questionnaire measures of interoception altered associations across measures. Results support the proposed distinction between self-reported interoceptive attention and accuracy and highlight the importance of considering the interpretation of questionnaire measures of interoception. The implications of these findings for theory, future research, and interpretation of existing research are discussed.

Sex differences in interoceptive accuracy: A meta-analysis

Interoceptive accuracy, the ability to correctly perceive internal signals arising from the body, is thought to be disrupted in numerous mental and physical health conditions. Whilst evidence suggests poorer interoceptive accuracy in females compared to males, raising the possibility that interoceptive differences may relate to sex differences in mental and physical health, results concerning sex differences in interoceptive accuracy are mixed. Given such ambiguity, this meta-analysis aimed to establish the presence or absence of sex differences in interoceptive accuracy across cardiac, respiratory, and gastric domains. A review of 7956 abstracts resulted in 93 eligible studies. Results demonstrated superior accuracy in males across cardiac, but not gastric, tasks, while findings on respiratory tasks were mixed. Effect sizes were consistent across cardiac tasks, but instability and/or moderate heterogeneity was observed across other domains, likely due to the small number of eligible studies. Despite such limitations, results indicate the possibility of sex differences across interoception tasks and domains. Methodological limitations concerning the influence of physiological factors, and directions for future research are discussed.

Atypical interoception as a common risk factor for psychopathology: A review

The inadequacy of a categorial approach to mental health diagnosis is now well-recognised, with many authors, diagnostic manuals and funding bodies advocating a dimensional, trans-diagnostic approach to mental health research. Variance in interoception, the ability to perceive one's internal bodily state, is reported across diagnostic boundaries, and is associated with atypical functioning across symptom categories. Drawing on behavioural and neuroscientific evidence, we outline current research on the contribution of interoception to numerous cognitive and affective abilities (in both typical and clinical populations), and describe the interoceptive atypicalities seen in a range of psychiatric conditions. We discuss the role that interoception may play in the development and maintenance of psychopathology, as well as the ways in which interoception may differ across clinical presentations. A number of important areas for further research on the role of interoception in psychopathology are highlighted.

Suicidal Ideation and Eating Disorder Symptoms in Adolescents: The Role of Interoceptive Deficits

Eating disorder symptoms and suicidal ideation are relatively common, and often begin to emerge in adolescence. Interoceptive deficits, or the inability to perceive and accurately identify the physiological condition of the body, is an established risk factor for both eating disorders and suicidal thoughts and behaviors. Despite this, longitudinal research examining the temporal dynamics between these variables is scarce, especially within adolescent samples. Using a three-wave longitudinal design, the present study tested bidirectional relationships between interoceptive deficits, eating disorder symptoms, and suicidal ideation to examine whether interoceptive deficits predicted eating disorder symptoms and suicidal ideation over the course of a year among a sample of adolescents. Participants were 436 community adolescents recruited from local middle- and high-schools. Data were collected at baseline, 6-month follow-up, and 12-month follow-up. Study measures assessed current suicidal ideation, eating disorder symptom severity, and interoceptive deficits. Autoregressive cross-lagged modeling was conducted in MPlus. We found baseline eating disorder symptoms significantly predicted suicidal ideation at 6-month follow-up when controlling for baseline suicidal ideation. Baseline interoceptive deficits significantly predicted eating disorder symptoms 6-months later, while 6-month follow-up interoceptive deficits significantly predicted 12-month follow-up suicidal ideation. Our findings highlight the need for early and regular assessment of suicidal ideation and eating disorder symptoms in adolescents. Given that interoceptive deficits was a shared risk factor for both conditions within this sample, these results underscore the need for targeted interventions aimed at improving interoception.

On the construct validity of interoceptive accuracy based on heartbeat counting: Cardiovascular determinants of absolute and tilt-induced change scores

Interoceptive accuracy (IAcc) as assessed with the heartbeat counting task (IAcc_HBCT) may be affected by a range of factors including (1.) the ability to adequately detect cardiac signals, indicated by IAcc in a heartbeat discrimination task (IAcc_HBDT), (2.) cardiac signal properties, affected by sympathetic and parasympathetic tone, and (3.) non-interoceptive processes, including time estimation accuracy (TEAcc). In the current study we investigated the contribution of these factors to absolute and Δ IAcc_HBCT scores, induced by passive head-up and head-down tilt in 49 healthy individuals. A set of hierarchical regression models showed IAcc_HBDT scores as the strongest and, across different orthostatic (tilt) conditions, most stable (positive) predictor of absolute and Δ IAcc_HBCT scores. Neither indicators of cardiac signal properties (except for HR in head-down-tilt), nor TEAcc predicted absolute or Δ IAcc_HBCT scores. These findings support the convergent and discriminant validity of absolute and Δ IAcc_HBCT scores.

Physical activity and interoceptive processing: Theoretical considerations for future research

Interoception, defined as the sense of the internal bodily state, plays a critical role in physical, cognitive, emotional and social well-being. Regarding physical well-being, contemporary models of exercise regulation incorporate interoceptive processes in the regulation of physical exertion. Top-down processes continuously monitor the physiological condition of the body to ensure allostasis is maintained, however, flagged perturbations also appear to influence these higher order processes in return. More specifically, enhancing one's physiological arousal by means of physical activity is a viable way of manipulating the afferent input entering the interoceptive system, appearing to optimise the integration of early sensory stimulation with later affective responses. Despite this, the relationship between physical activity and top-down regulation is underrepresented in interoceptive research. We here address this gap by integrating findings from different disciplines to support the overlapping mechanisms, with the hope of stimulating further research in this field. Developing our understanding of how interoceptive processes are shaped by physical activity could hold significant clinical implications considering the impact of interoceptive deficits to mental health and well-being.

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.

Noradrenergic activation induced by yohimbine decreases interoceptive accuracy in healthy individuals with childhood adversity

Acute stress affects interoception, but it remains unclear if this is due to activation of the sympatho-adreno-medullary (SAM) or hypothalamic-pituitary-adrenocortical axis. This study aimed to investigate the effect of SAM axis activation on interoceptive accuracy (IAcc). Central alpha2-adrenergic receptors represent a negative feedback mechanism of the SAM axis. Major depressive disorder and adverse childhood experiences (ACE) are associated with alterations in the biological stress systems, including central alpha2-adrenergic receptors. Here, healthy individuals with and without ACE as well as depressive patients with and without ACE (n = 114; all without antidepressant medication) were tested after yohimbine (alpha2-adrenergic antagonist) and placebo. We assessed IAcc and sensibility in a heartbeat counting task. Increases in systolic and diastolic blood pressure after yohimbine confirmed successful SAM axis activation. IAcc decreased after yohimbine only in the healthy group with ACE, but remained unchanged in all other groups (Group × Drug interaction). This effect may be due to selective upregulation of alpha2-adrenergic receptors after childhood trauma, which reduces capacity for attention focus on heartbeats. The sympathetic neural pathway including alpha2-adrenergic circuitries may be essential for mediating interoceptive signal transmission. Suppressed processing of physical sensations in stressful situations may represent an adaptive response in healthy individuals who experienced ACE.

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.

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.

The relationship between heartbeat counting and heartbeat discrimination: A meta-analysis

Interoception concerns the perception of the body's internal state. Despite the importance of this ability for health and aspects of higher-order cognition, its measurement remains problematic. Most studies of interoception employ one of two tasks: the heartbeat counting or heartbeat discrimination task. These tasks are thought to index common abilities, an assertion often used to justify the use of a single measure of cardiac interoception. However, mixed findings regarding the relationship between performance on these tasks raises the question of whether they can be used interchangeably to assess interoceptive accuracy, confidence and awareness ('metacognition'). The present study employed a meta-analytical approach to assess the association between these tasks. Pooled findings from 22 studies revealed a small relationship between accuracy scores on the measures. Additional analyses demonstrated a moderate relationship between confidence ratings but no association between measures of interoceptive awareness. These findings question the interchangeable use of the two tasks.

Distinctive body perception mechanisms in high versus low symptom reporters: A neurophysiological model for medically-unexplained symptoms

OBJECTIVE

The neurophysiological processes involved in the generation of medically-unexplained symptoms (MUS) remain unclear. This study tested three assumptions of the perception-filter model contributing to MUS: (I.) increased bodily signal strength (II.) decreased filter function, (III.) increased perception.

METHODS

In this cross-sectional, observational study, trait MUS were assessed by a web-based survey (N = 486). The upper and lower decile were identified as extreme groups of high (HSR; n = 29; 26 women; Mage = 26.0 years) and low symptom reporters (LSR; n = 29; 21 women; Mage = 28.4 years). Mean heart rate (HR) and heart rate variability (HRV), and cortisol awakening response (CAR) were assessed as indicators of bodily signal strength (I.). Heartbeat-evoked potentials (HEPs) were assessed during rest and a heartbeat perception task. HEPs reflect attentional resources allocated towards heartbeats and served as index of filter function (II.). Interoceptive accuracy (IAc) in heartbeat perception was assessed as an indicator of perception (III.).

RESULTS

HSR showed higher HR and lower HRV (RMSSD) than LSR (I.), but no differences in CAR. HSR exhibited a stronger increase of HEPs when attention was focused on heartbeats than LSR (II.); there were no group differences in IAc (III.).

CONCLUSIONS

The perception-filter model was partially confirmed in that HSR showed altered bodily signals suggesting higher sympathetic activity (I.); higher HEP increases indicated increased filter function for bodily signals (II.). As more attentional resources are mobilized to process heartbeats, but perception accuracy remains unchanged (III.), this overflow could be responsible for detecting minor bodily changes associated with MUS.

A Systematic Review of Associations Between Interoception, Vagal Tone, and Emotional Regulation: Potential Applications for Mental Health, Wellbeing, Psychological Flexibility, and Chronic Conditions

Background: Interoception and heart rate variability have been found to predict outcomes of mental health and well-being. However, these have usually been investigated independently of one another.

Objectives: This systematic review aimed to explore a key gap in the current literature, that being, identifying whether HRV and interoception predict emotional regulation outcomes and strategies.

Methods: The process of article retrieval and selection followed the PRISMA guidelines. Databases PsychINFO, Web of Science, PubMed, CINAHL, and MEDLINE were scanned for papers published. Preliminary inclusion and exclusion criteria were specified following the PICO framework, whilst the CHARMS framework was used to help formulate the research question, and critically assess for bias.

Results: Two hundred and thirty-seven studies were identified after initial database searches. Of these, eight studies were included in the final selection. Six studies explored the associations between HRV and ER, whilst three investigated the associations between interoception and ER (one study included both). Results show that greater HRV and interoception are associated with better ER. Specifically, high parasympathetic activity largely predicted the use of adaptive ER strategies such as reappraisal, and better acceptance of emotions. High interoception, instead, was predictive of effective downregulation of negative emotions and handling of social uncertainty, there was no association with any specific ER strategy.

Conclusions: Awareness of one's own bodily feelings and vagal activation seem to be of central importance for the effective regulation of emotional responses. However, one limitation is the small sample of studies found, thus more studies in this area are needed in the future.

Cortisol rapidly increases baroreflex sensitivity of heart rate control, but does not affect cardiac modulation of startle

Cortisol, the final product of human HPA axis activation, rapidly modulates the cortical processing of afferent signals originating from the cardiovascular system. While peripheral effects have been excluded, it remains unclear whether this effect is mediated by cortical or subcortical (e.g. brainstem) CNS mechanisms. Cardiac modulation of startle (CMS) has been proposed as a method to reflect cardio-afferent signals at subcortical (potentially brainstem-) level. Using a single blind, randomized controlled design, the cortisol group (n = 16 volunteers) received 1 mg cortisol intravenously, while the control group (n = 16) received a placebo substance. The CMS procedure involved the assessment of eye blink responses to acoustic startle stimuli elicited at six different latencies to ECG-recorded R-waves (R + 0, 100, 200, 300, 400 and 500 ms). CMS was assessed at four measurement points: baseline, -16 min, +0 min, and +16 min relative to substance application. Baroreflex sensitivity (BRS) of heart rate (HR) control was measured non-invasively based on spontaneous beat-to-beat HR and systolic blood pressure changes. In the cortisol group, salivary cortisol concentration increased after IV cortisol administration, indicating effective distribution of the substance throughout the body. Furthermore, BRS increased in the cortisol group after cortisol infusion. There was no effect of cortisol on the CMS effect, however. These results suggest that low doses of cortisol do not affect baro-afferent signals, but central or efferent components of the arterial baroreflex circuit presumably via rapid, non-genomic mechanisms.

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.

Classifying individual differences in interoception: Implications for the measurement of interoceptive awareness

It has been suggested that individual differences in interoception (the perception of the body’s internal state) can be divided into three distinct dimensions: interoceptive accuracy (performance on objective tests of interoceptive accuracy), interoceptive sensibility (self-reported beliefs concerning one’s own interoception) and interoceptive awareness (a metacognitive measure indexed by the correspondence between interoceptive accuracy and interoceptive sensibility). Research conducted under this model underscores the importance of interoceptive awareness for a variety of disorder-specific and transdiagnostic symptoms. However, the clinical importance of interoceptive awareness means that this aspect of interoception warrants further scrutiny, and such scrutiny suggests that revision of the three-dimensional model of interoception is necessary. In this theoretical paper, we outline such a revision, highlighting a need to distinguish not only how interoception is measured (objective measures vs. self-report), but also what is measured (accuracy vs. attention). The model refines how individual differences in interoception are categorised, with important consequences for the measurement of interoceptive awareness. Such a revision may help researchers to identify the strengths and weaknesses in interoception observed across clinical conditions, and to isolate clinically relevant individual differences.

My body, your emotions: Viscerosomatic modulation of facial expression discrimination

Interoception reflects the ability to observe one's innermost bodily states. Here, we assessed whether interoceptive accuracy (IA) is related to the empathic ability to discriminate others' emotions. Participants (N = 111) completed a heartbeat tracking task, as well as an emotional go/no-go task with fearful and disgusted faces. Empathic facial mimicry during the go/no-go task was measured using electromyography (EMG) of the Corrugator Supercilii muscle. Higher IA was associated with higher perceptual sensitivity for emotional faces but was unrelated to response bias. Individuals higher in IA had stronger coupling between facial EMG and task performance. IA and facial EMG were associated with Go but not with NoGo trials, consistent with a specific modulation of perceptual sensitivity. These results suggest that tuning into one's own viscerosomatic signals relates to empathic mimicry and perception of others' emotional states.

Testing the independence of self-reported interoceptive accuracy and attention

It has recently been proposed that measures of the perception of the state of one’s own body (“interoception”) can be categorised as one of several types depending on both how an assessment is obtained (objective measurement vs. self-report) and what is assessed (degree of interoceptive attention vs. accuracy of interoceptive perception). Under this model, a distinction is made between beliefs regarding the degree to which interoceptive signals are the object of attention and beliefs regarding one’s ability to perceive accurately interoceptive signals. This distinction is difficult to test, however, because of the paucity of measures designed to assess self-reported perception of one’s own interoceptive accuracy. This article therefore reports on the development of such a measure, the Interoceptive Accuracy Scale (IAS). Use of this measure enables assessment of the proposed distinction between beliefs regarding attention to, and accuracy in perceiving, interoceptive signals. Across six studies, we report on the development of the IAS and, importantly, its relationship with measures of trait self-reported interoceptive attention, objective interoceptive accuracy, confidence in the accuracy of specific interoceptive percepts, and metacognition with respect to interoceptive accuracy. Results support the distinction between individual differences in perceived attention towards interoceptive information and the accuracy of interoceptive perception.

Temporal Matching Between Interoception and Exteroception

Abstract. Recent studies on interoception emphasize the importance of multisensory integration between interoception and exteroception. One of the methods frequently applied for assessing interoceptive sensitivity is the heartbeat discrimination task, where individuals judge whether the timing of external stimuli (e.g., tones) are synchronized to their own heartbeat. Despite its extensive use in research, the neural dynamics underlying the temporal matching between interoceptive and exteroceptive stimuli in this task have remained unclear. The present study used electroencephalography (EEG) to examine the neural responses of healthy participants who performed a heartbeat discrimination task. We analyzed the differences between EEG responses to tones, which were likely to be perceived as “heartbeat-synchronous” (200 ms delayed from the R wave) or “heartbeat-asynchronous” (0 ms delayed). Possible associations of these neural differentiations with task performance were also investigated. Compared with the responses to heartbeat-asynchronous tones, heartbeat-synchronous tones caused a relative decrease in early gamma-band EEG response and an increase in later P2 event-related potential (ERP) amplitude. Condition differences in the EEG/ERP measures were not significantly correlated with the behavioral measures. The mechanisms underlying the observed neural responses and the possibility of electrophysiological measurement of interoceptive sensitivity are discussed in terms of two perspectives: the predictive coding framework and the cardiac-phase-dependent baroreceptor function.

Parental divorce is associated with an increased risk to develop mental disorders in women

BACKGROUND

Parental divorce has been associated with reduced well-being in young adults. It is, however, unclear whether this finding is clinically relevant as studies using structured clinical interviews are missing. This study, therefore, investigated if young adults with divorced parents are at risk to develop mental disorders. Furthermore, differences in parental care, social connectedness, chronic stress and traumatic experiences between children of divorced and non-divorced parents were investigated.

METHODS

121 women (mean age: 23 years) were interviewed using the Structured Clinical Interview for DSM-IV Axis I (i.e., major mental disorders) and II (i.e., personality disorders) Disorders and asked to complete questionnaires assessing parental care, social connectedness (loneliness, attachment anxiety and avoidance), chronic stress, childhood trauma and depression.

RESULTS

Young adults of divorced parents had a higher risk for Axis I but not Axis II disorders as compared to young adults of non-divorced parents. Participants from divorced families as compared to non-divorced families reported more depression, loneliness, childhood trauma, attachment avoidance, attachment anxiety, chronic stress and less paterntal care.

LIMITATIONS

Due to the cross-sectional design of this study, conclusions about causality remain speculative.

CONCLUSION

The increased vulnerability of children of divorced parents to develop mental disorders, and to experience more chronic stress, loneliness, attachment avoidance, attachment anxiety, and traumatic experiences during childhood is alarming and highlights the importance of prevention programs and psycho-education during the process of parental divorce. Parental support with regard to adequate caregiving is needed to help parents to better support their children during and after their divorce.

Mindfulness, Interoception, and the Body: A Contemporary Perspective

Mindfulness is often used as an umbrella term to characterize a large number of practices, processes, and characteristics. Critics argue that this broad definition has led to misinformation, misunderstanding, and a general lack of methodologically rigorous research. Some of the confusion surrounding mindfulness is also believed to stem from an undifferentiated use of the term mindfulness and meditation. Mindfulness and all other forms of meditation have been shown to modulate the insula, which is the primary hub for interoception. Some have argued that interoception is foundational to mindfulness and may be the primary mechanism by which one benefits from the practice. However, much like the mindfulness literature, interoception remains broadly defined often without precision and with domain-specific meanings and implications. Research demonstrates that the insula and surrounding neural circuits are believed to be responsible for a number of other functions beyond interoception including attention, awareness, and all subjective experiences, much of which has been linked to the mindfulness literature. It has been assumed that mindfulness produces these neuroplasticity and functional effects. There is evidence that mindfulness and some of its benefits may be better described as increased interoception as a result of the neuroplasticity changes in the insula, and the development of the insula and surrounding neural circuits may cultivate dispositional mindfulness. The purposes of this article are to (1) highlight that it may be more accurate to link many of the identified benefits in the mindfulness literature to interoception and its neurological correlates and (2) propose attentional style as a means to clarify some of the confusion surrounding mindfulness, interoception, and meditation. Different meditations require different attentional styles. Attention can be analogous to a focal point with each focal point providing a unique perspective. Given that all meditative techniques modulate the insula, each meditation can provide a unique perspective from which to investigate complex interoceptive signals that may be unavailable from other meditative traditions. It may prove more useful to anchor scientific findings in the concrete body as a means to investigate those rather than a set of abstract, broadly defined meditative techniques.

The Feeling of Me Feeling for You: Interoception, Alexithymia and Empathy in Autism

Following recent evidence for a link between interoception, emotion and empathy, we investigated relationships between these factors in autism spectrum disorder (ASD). 26 adults with ASD and 26 healthy participants completed tasks measuring interoception, alexithymia and empathy. ASD participants with alexithymia demonstrated lower cognitive and affective empathy than ASD participants without alexithymia. ASD participants showed reduced interoceptive sensitivity (IS), and also reduced interoceptive awareness (IA). IA was correlated with empathy and alexithymia, but IS was related to neither. Alexithymia fulfilled a mediating role between IA and empathy. Our findings are suggestive of an alexithymic subgroup in ASD, with distinct interoceptive processing abilities, and have implications for diagnosis and interventions.

Altered interoceptive processing in smokers: Evidence from the heartbeat tracking task

Neuroimaging evidence suggests that interoceptive processing might be altered in nicotine addiction, however this has not yet been confirmed with behavioural measures. Therefore, we investigated the perception of internal bodily states in smokers (n = 49) and people who had never smoked (n = 51), by measuring interoceptive accuracy (IAcc) and interoceptive sensibility (IS). IAcc was measured with a heartbeat tracking task and a heartbeat discrimination task. Performance on the heartbeat tracking task may be influenced by one's ability to estimate an elapsed time interval so this was controlled by also administering a time-estimation (TE) task. IS was measured using two sub-scales from the Multidimensional Assessment of Interoceptive Awareness (MAIA). All smokers completed the Revised Fagerström Test for Nicotine Dependence (FTND-R) to measure addiction severity. Non-smokers performed significantly better than smokers on the heartbeat tracking task. There were no significant group differences observed for the remaining variables. Furthermore, none of the variables predicted addiction severity. This is the first demonstration of behavioural differences in interoception between smokers and non-smokers.

The impact of valence framing on response expectancies of side effects and subsequent experiences: a randomised controlled trial

Objective: Pre-treatment side effect expectancies often influence subsequent experiences; however, expectancy-based reduction strategies are lacking. We explored whether framing information about adverse responses (in positive or negative formats) altered expectancies and experiences of a cold pressor task. We further investigated associations between expectancies and experiences, to inform potential interventions. Design: Healthy volunteers (N = 134), randomised to receive positively- or negatively-framed pre-cold pressor task information, self-rated 12 expectancies for cold pressor experiences, emotional state and coping style. Main Outcome Measures: Self-reports of the same 12-experiences (recorded during and after the experiment) were assessed. Results: Framing had minimal impact on expectancies and experiences; however, discomfort threshold (p = .08, d = 0.22) showed a trend in the expected direction. Hierarchical regressions revealed expectancies uniquely, significantly predicted 6-23% of the variance for 11 subsequent experiences. Following a popular charity event (Ice Bucket Challenge), all participants showed higher 'discomfort thresholds' (p = .001, d = 0.59), and those in the negative frame reported more overall 'discomfort' (p = .01, d = 0.60) than participants in the positive condition. Conclusion: Expectancies uniquely influenced subsequent cold pressor experiences. Framing had minimal impact in this 'analogue' medical setting, only influencing 'discomfort threshold'. 'Discomfort threshold' and overall 'discomfort' were also impacted by a social media challenge, highlighting a potential area for intervention.

Dimensions of interoception predict premonitory urges and tic severity in Tourette syndrome

Interoceptive processes in Tourette syndrome may foster the premonitory urges that commonly precede tics. Twenty-one adults with TS and 22 controls completed heartbeat tracking and discrimination tasks. Three dimensions of interoception were examined: objective accuracy, metacognitive awareness, and subjective (self-report) sensibility. Trait interoceptive prediction error was calculated as the discrepancy between accuracy and sensibility. Participants with TS had numerically lower interoceptive accuracy on the heartbeat tracking task, and increased self-reported interoceptive sensibility. While these group differences were not significant, the discrepancy between lower interoceptive accuracy and heightened sensibility, i.e. the trait interoceptive prediction error, was significantly greater in TS compared to controls. This suggests a heightened higher-order sensitivity to bodily sensations in TS, relative to a noisier perceptual representation of afferent bodily signals. Moreover, interoceptive sensibility predicted the severity of premonitory sensations and tics. This suggests interventions that work to align dimensions of interoceptive experience in TS hold therapeutic potential.

Childhood Trauma Affects Stress-Related Interoceptive Accuracy

Early life adversity (ELA) may cause permanent disturbances in brain-body signaling. These disturbances are thought to contribute to physical symptoms and emotional dysregulation in adulthood. The current study investigated the effects of childhood trauma on young adults' interoceptive accuracy as an indicator of brain-body communication that may be dysregulated by ELA. Sixty-six participants completed an online questionnaire followed by a laboratory session including the socially evaluated cold pressor stress test during which ECG, salivary cortisol, and interoceptive accuracy were assessed. Childhood trauma was negatively related to interoceptive accuracy (IAc) after the stressor. This stress effect could not be observed for heart rate and cortisol, which were unrelated to IAc. Participants reporting higher baseline unpleasantness exhibited lower IAc after the stressor, while increases in unpleasantness due to the stressor were associated with higher IAc. Unpleasantness at baseline mediated the effect of childhood trauma on IAc after the stressor.

The neurobiology of interoception in health and disease

Interoception is the sensing of internal bodily sensations. Interoception is an umbrella term that encompasses (1) the afferent (body-to-brain) signaling through distinct neural and humoral (including immune and endocrine) channels; (2) the neural encoding, representation, and integration of this information concerning internal bodily state; (3) the influence of such information on other perceptions, cognitions, and behaviors; (4) and the psychological expression of these representations as consciously accessible physical sensations and feelings. Interoceptive mechanisms ensure physiological health through the cerebral coordination of homeostatic reflexes and allostatic responses that include motivational behaviors and associated affective and emotional feelings. Furthermore, the conscious, unitary sense of self in time and space may be grounded in the primacy and lifelong continuity of interoception. Body-to-brain interactions influence physical and mental well-being. Consequently, we show that systematic investigation of how individual differences, and within-individual changes, in interoceptive processing can contribute to the mechanistic understanding of physical and psychological disorders. We present a neurobiological overview of interoception and describe how interoceptive impairments at different levels relate to specific physical and mental health conditions, including sickness behaviors and fatigue, depression, eating disorders, autism, and anxiety. We frame these findings in an interoceptive predictive processing framework and highlight potential new avenues for treatments.

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.

Multichannel Investigation of Interoception: Sensitivity Is Not a Generalizable Feature

Objective: The term interoception refers to the perception of bodily cues. In empirical studies, it is assessed using heartbeat detection or tracking tasks, often with the implicit assumption that cardioception reflects general interoceptive ability. Studies that applied a multichannel approach measured only a limited number of modalities. In the current study, six modalities were assessed to gain a deeper understanding of the relationship between the different sensory channels of interoception. Methods: For 118 university students (53% male) gastric perception (water load test), heartbeat perception (Schandry task), proprioception (elbow joint), ischemic pain (tourniquet technique), balancing ability (one leg stand), and perception of bitter taste were measured. Pair-wise correlation analysis and exploratory factor analyses (principal component analysis (PCA) and maximum likelihood (ML) extraction with oblimin rotation) were then carried out with a three-factor solution to investigate the underlying associations. Results: Correlation analysis only revealed significant associations between variables belonging to the same sensory modality (gastric perception, pain, bitter taste). Similarly, the three factors that consistently emerged in the factor analyses represented the three aforementioned modalities. Discussion: Interoceptive sensitivity assessed by using one channel only cannot be generalized. Interoceptive modalities carrying crucial information for survival are not integrated with other channels.