BackgroundThe etiology of many chronic pain conditions is still poorly understood. According to the perception-filter model, amplification (stage I.) and insufficient filtering (stage II.) of afferent bodily signals results in the increased perception of physical sensations (stage III.).MethodsFocusing on cardiac interoception, we tested if these hypothesized alterations in stages I.-III. apply to a sample of 76 in-patients with chronic pain (Mage = 50.7, 53 females). Heart rate (HR) and heart rate variability (HRV) were assessed as indicators of afferent bodily signal strength (stage I.). The difference between heartbeat-evoked potentials (HEPs) during a resting phase and a heartbeat counting task (HCT), i.e., ΔHEP, was used as an indicator of filter system activity. Interoceptive accuracy (IAcc) in the HCT and a heartbeat discrimination task (HDT) served as indicators of perception of afferent bodily signals.ResultsHR did not predict either indicator of IAcc. LF HRV was a positive predictor of IAccHCT and HF HRV positively predicted both IAccHCT and IAccHDT. HEP amplitudes did not differ between the HCT and the resting period and ΔHEP did not moderate any of the relationships between indicators of bodily signal strength (stage I.) and IAcc (stage III.). Neither indicator of IAcc (stage lll.) was significantly associated with measures of symptom report.ConclusionAlterations in the processing of bodily signals as suggested by the perception-filter model do not apply to chronic pain conditions. Future studies should focus on investigating pain-specific processing of bodily signals.

The high prevalence of obesity and low treatment response in eating disorders highlight the need for a better understanding of eating regulation. Gastric interoception - the perception of signals such as hunger and satiation - plays a key role in aligning food intake with physiological needs. This study investigated how acute stress, emotion regulation difficulties, and eating traits influence gastric interoceptive sensitivity. Ninety-four fasting participants completed both a stress and control task in counterbalanced order across two laboratory sessions. Gastric interoceptive sensitivity was assessed using a novel method, the Magic Table (MT), in which participants ate yogurt from a self-refilling bowl until satiation and fullness. Multi-level modeling evaluated stress effects and moderation by self-reported eating traits and emotion regulation. For validation, 61 participants also completed the established Two-step Water Load Test (WLT-II) and free food consumption. Medium to strong correlations between MT indices, WLT-II, and food intake supported the validity of the MT. While stress had no overall effect on gastric interoception, cross-level interactions showed reduced fullness sensitivity under stress in individuals with high emotion regulation difficulties, restrained, and uncontrolled eating. These findings suggest that this group may be at risk for interoceptive desensitization under stress and inform studies on interoception-focused interventions.

Human learning and memory are considered 'embodied', but it is unclear which body signals affect which memory facet. We investigated whether ascending cardiac signals affect memory encoding and consolidation. Due to its relevance for social behavior, this study investigated identity and expression memory for emotional faces. To implement different conditions of ascending cardiac signals for encoding, participants viewed happy and angry faces for 150 ms time-locked either to the early (R-wave +230 ms) or late cardiac cycle phase (R-wave +530 ms), which differ in their feedback from arterial baroreceptors. Participants then underwent either a stress (n = 30; Socially Evaluated Cold Pressor Test/SECPT) or a no-stress procedure (n = 29) to apply conditions of high vs. low cardiac signals in the consolidation phase. Recognition of face identity and emotional expression was tested 30 min and 24 h after acquisition. Memory for both identity and expression was significantly better when encoded in the late cardiac cycle phase, both for happy and angry faces. Memory performance declined over time. Although the SECPT increased heart rate, systolic (SBP) and diastolic blood pressure, as well as salivary cortisol, it did not affect memory. Nevertheless, stress responsiveness of cortisol was a positive predictor and SBP responsiveness was a negative predictor of expression memory. Our findings suggest that increased baroreceptor feedback globally attenuates declarative memory encoding for emotional faces (i.e. identity/expression memory), independent of valence. In contrast, the effect of perturbations in ascending cardiac signals by acute stress on consolidation of identity or expression memory depends on stress axis responsiveness.

Interoception, the processing and perception of internal bodily signals, regulates a wide range of psychological and somatic functions, including emotional experiences, bodily symptom perception, self-awareness and decision-making, highlighting its important role in the maintenance of bodily and mental homeostasis. Traditionally, interoception has been studied within single organ domains, with findings often generalized to interoception as a whole. However, evidence suggests interoceptive abilities may be domain-specific rather than a general ability. This pilot study investigated how perceptual and affective dimensions of interoception relate across organ systems. Thirty-three healthy adults completed comparable magnitude estimation and sustained stimulation tasks, allowing for comparisons across the respiratory, esophageal, and cardiac domain in a within-subjects design. Respiratory sensations were evoked through inspiratory resistive loads, esophageal sensations through balloon inflations, and cardiac sensations via graded cycle ergometer exercise. Interoceptive sensitivity, the ability to perceptually discriminate between stimulation levels, was quantified as the slope of intensity ratings relative to stimulation intensity. Acute affective responses were assessed through unpleasantness ratings during sustained stimulation. Results revealed no significant correlations in interoceptive sensitivity across domains, with Bayesian analyses providing anecdotal support for the null hypothesis. In contrast, acute affective responses showed partial convergence: respiratory unpleasantness ratings correlated significantly with both esophageal and cardiac ratings, whereas esophageal and cardiac ratings were not significantly correlated. These findings support a multidimensional model of interoceptive processing, where interoceptive sensitivity appears domain-specific, while acute affective responses show partial generalization across organ systems. The results caution against generalizing findings from single-organ paradigms to overall interoceptive functioning.

Previous findings suggest that acute stress enhances attention focused on heartbeats, which is the definition of the construct cardiac "interoceptive attention" (IAt). The difference of heartbeat-evoked potentials (HEPs) assessed while performing a heartbeat counting task (HCT) versus a distraction task is considered an indicator of cardiac IAt. The aim of this study was to investigate whether acute stress enhances cardiac IAt and how activation of the sympatho-adrenomedullary (SAM) and the hypothalamic-pituitary-adrenocortical (HPA) stress axis contributes to this potential effect. Sixty-six young, healthy individuals were randomly assigned to a stress (socially evaluated cold pressor test/SECPT; n = 32) or a control group (n = 34), and underwent a HCT and a distraction task once before and three times (+0, +20, +40 min) after the intervention (SECPT/control). The SECPT effectively increased heart rate, systolic/diastolic blood pressure, and cortisol release. Cardiac interoceptive accuracy based on the HCT was unaffected by stress. Individuals in the SECPT group showed an increase in HEPs (R-wave +455-595 ms) assessed during the HCT 40 min after the intervention (at F8, Cz, C4, CP6, P8). These findings suggest that acute stress may selectively enhance cardiac IAt. Its primarily right-hemispheric topography suggests the involvement of insular activity in mediating this effect. Exploratory analyses in the stress group showed that the responsiveness of HEPs to the stressor (+40 min vs. before) was negatively correlated with stress responsiveness in systolic blood pressure and pain intensity/unpleasantness. Future studies should clarify whether this late effect of acute stress on IAt is due to parasympathetic deactivation during stress recovery, and if their underlying neural networks (e.g., cardiac parasympathetic afferents) play a role in mediating IAt.

OBJECTIVE:This study provides a comprehensive assessment of cardiac interoception in individuals with binge eating (BE) behavior and compares their emotional experience and affective state related to heartbeat perception with those of healthy controls (HCs). METHOD:After a 5-min resting phase, participants (n = 28 BE group, n = 28 HC group) completed the heartbeat counting task, with concurrent EEG and ECG recording. Indices for interoceptive accuracy (IAcc), interoceptive beliefs (IBe), and interoceptive insight (IIn) were computed. Heart rate (HR) and heart rate variability (HRV) served as indicators of bodily signal strength. Heartbeat-evoked potentials (HEPs) were derived to assess the neural representation of cardio-afferent signals at the cortical level during rest or task performance. Emotional experiences and changes in affective state from pre-to post-task were assessed using self-reports. RESULTS:The BE group exhibited lower mean HR and higher HRV compared to HCs. No group differences were found in IAcc, IBe, or IIn. HCs showed increased HEP amplitudes during the task compared to rest, whereas no such effect was observed in the BE group. Both groups reported an increase in negative affect from pre-to post-task, with the BE group experiencing significantly higher negative affect post-task. DISCUSSION:The altered neural representation observed in the BE group may reflect disengagement from bodily sensations, which may impair emotion processing and regulation, potentially contributing to BE behavior. Further research is warranted to determine whether this pattern is specific BE-related eating disorders (EDs) or relevant to EDs in general.

Interoceptive accuracy, the ability to correctly perceive internal body signals such as heartbeats, has been empirically and theoretically linked to stress. However, issues with the measurement of both interoceptive accuracy and stress have led to lack of clarity regarding this relationship. This systematic review and meta-analysis aimed to clarify whether interoceptive accuracy is associated with different facets of stress, including - physical, cognitive and self-reported stressors and the physiological stress response. A systematic search identified 2014 abstracts. Twenty-eight authors were contacted to request data for eligible studies, which yielded a final sample of 20 studies. Results revealed a positive association between heartbeat counting task (HCT) performance and acute physical stressors, and a negative association between HCT performance and physiological stress responses. No significant relationships were observed between stress and interoceptive accuracy assessed by the heartbeat discrimination task. While these findings offer tentative support for stress-interoceptive accuracy associations, they must be interpreted with caution given substantial heterogeneity in stress measures, limited use of interoception tasks beyond the HCT, and ongoing concerns regarding task validity. Implications for future research and methodological recommendations are discussed.

The bi-directional communication of the brain-body axis, including afferent (e.g., interoception) and efferent signal transmission (e.g., stress), is critical for understanding stress-related disorders. Transcranial magnetic stimulation using theta burst stimulation (TBS) protocols can be used to inhibit or to enhance activity in the interoceptive brain network (IBN), which may also affect efferent signal transmission, such as stress. This preliminary study aimed at investigating the effects of different TBS protocols that modulate IBN activity on physiological stress responses, as well as of stress responses on interoceptive accuracy (IAc) and heartbeat-evoked potentials (HEPs), which are two measures of cardiac interoception. Twenty-one participants were randomly assigned to either an inhibiting continuous protocol (cTBS), facilitating intermittent stimulation (iTBS), or an ineffective intermediate stimulation (imTBS) protocol targeting the right supramarginal gyrus (rSMG). Participants underwent both a stress (Socially Evaluated Cold Pressor Task) and a control condition. Stress significantly increased systolic/diastolic blood pressure (SBP/DBP) and cortisol levels. Stress did not affect IAc, but increased HEP amplitudes 455–595 ms after the R-wave, regardless of the stimulation protocol. Moreover, we found a trend towards an increase of negativity of HEPs 860–1000 ms, after the R-wave in the cTBS. No further effects of the stimulation condition on stress responses or measures of cardiac interoception were observed. This offers preliminary evidence that IBN stimulation or inhibition does not affect stress responsiveness. Acute stress affects interoceptive attention (reflected by HEPs), but not IAc. Hence, acute stress may enhance attentional resources focused on interoceptive sensations, potentially at the cost of resources for processing exteroceptive sensory information.

Background and objectivesSelf-regulatory processes, namely behavioral regulation (in terms of executive functions) and emotion regulation, are assumed to be central for test anxiety. Both self-regulation components, along with vagally-mediated heart rate variability (HRV) - a proposed concomitant of top-down self-regulation - are associated with anxiety.DesignA longitudinal design was adopted to test the hypotheses that (1) higher vagally-mediated HRV, (2) adaptive emotion regulation and (3) better executive functioning (i.e., higher inhibitory control) at the semester beginning (t1) predict lower levels of test anxiety at the end of the semester (t2).MethodsA sample of N = 70 (58 female) university students (M [SD] age = 25.04 [7.14] years) completed a measurement of resting HRV (RMSSD), performed an affective go/no-go task, and reported on emotion regulation and test anxiety at t1. Test anxiety and certain examination characteristics were assessed at t2. A hierarchical regression analysis was conducted to test the hypotheses.ResultsSupporting hypothesis 1, HRV at t1 significantly predicted test anxiety at t2, whereas emotion regulation and inhibitory control were no significant predictors.ConclusionsAs vagally-mediated HRV seems meaningful for the prediction of test anxiety, interventions designed to reduce test anxiety could benefit from incorporating HRV biofeedback training.

Interoception, the perception and processing of signals from within the body, plays a central role in various aspects of human cognition, affect, and behavior. This study investigates the effects of theta burst stimulation (TBS) on cardiac interoception, focusing on modulation of activity of the interoceptive brain network (IBN). Twenty-two participants underwent three stimulation protocols: an inhibitory (continuous TBS, cTBS), a facilitatory (intermittent TBS, iTBS), and an ineffective control (intermediate TBS, imTBS) protocol, targeting the right supramarginal gyrus (rSMG). Stimulation of the rSMG allows, thanks to its strong functional connectivity with the right anterior insula, an indirect modulation of the activity of the IBN. We observed an increase in heartbeat-evoked potentials following facilitatory stimulation (iTBS), suggesting increased activity within the interoceptive network. In contrast, we found no effects of inhibitory (cTBS) or ineffective control (imTBS) protocols on HEPs. Furthermore, cardiac interoceptive accuracy (IAc) in a heartbeat perception task was not significantly affected by the different stimulation protocols. In conclusion, the current rSMG facilitation protocol based on iTBS is the first to enhance activity in the IBN. The result that only HEPs, but not cardiac IAc was affected, suggests that rSMG stimulation selectively enhances cardiac interoceptive attention.

Patients with borderline personality disorder (BPD) suffer from severe emotional dysregulation and disturbances in body image and self-perception. Interoception, the processing and perception of internal body signals, is closely linked to emotional processing, but it remains unclear whether BPD impairs specific interoceptive facets and how these deficits respond to treatment. We investigated the two key interoceptive facets, accuracy and attention, in 55 BPD patients and 31 healthy controls (HC) using self-report and objective measures before and after four-week residential Dialectical Behavior Therapy (DBT). Interoceptive accuracy and its metacognitive awareness were evaluated using a heartbeat discrimination task, while interoceptive attention was measured through questionnaires, intensity ratings, and both uni- and multivariate neural responses during a functional magnetic resonance imaging (fMRI) interoceptive attention task. Before DBT, BPD patients showed reduced self-reported interoceptive attention, which was associated with more interpersonal problems. Patients further exhibited higher similarity in activity patterns evoked by cardiac interoceptive and exteroceptive attention in the insular and dorsal anterior cingulate cortex. There were no significant group differences in behavioral or self-reported interoceptive accuracy or metacognitive awareness. However, behavioral interoceptive accuracy was impaired in BPD patients with more severe symptoms. After four-week residential DBT, self-reported interoceptive attention significantly improved, while other interoceptive facets showed no significant changes. BPD involves disturbances in specific interoceptive facets that respond differently to treatment. Our findings support multifaceted assessments of interoception and the potential benefit of interoceptive attention training for all BPD patients, with additional accuracy training in more severe cases.

Transcutaneous auricular vagus nerve stimulation (taVNS) affects autonomic function and enhances cognitive performance by increasing vagal activation and central noradrenergic activity. Nevertheless, the impact of taVNS on acute mental stress remains largely unexplored. This study examined whether taVNS can mitigate the acute sympathetic stress response and improve cognitive performance during a socially evaluated version of the Paced Auditory Serial Addition Task (PASAT). The PASAT is a demanding task that assesses working memory and divided attention and serves as a potent stressor. Forty-one young healthy volunteers were randomly assigned to receive either taVNS stimulation (n = 21) at the left cymba conchae or a sham stimulation (n = 20) at the ear lobe. Participants received 15-min stimulation before they were challenged with the PASAT while the stimulation continued. Electrocardiogram, electrodermal activity and self-reports of stress and anxiety were collected. Transcutaneous auricular vagus nerve stimulation increased heart rate variability and sympathetic electrodermal activity during the stimulation. Self-reports, cognitive performance and physiological stress responses remained unaffected by taVNS. Physiological measures were highly intercorrelated in participants receiving taVNS. Transcutaneous auricular vagus nerve stimulation did not influence physiological, psychological or behavioral responses to an acute mental/social stressor. The strong intercorrelation between sympathetic and parasympathetic indexes in the taVNS group, however, suggests that taVNS improves autonomic regulation in healthy participants.

Background: Overcommitment (OC) is highly prevalent in health care employees, and may predict depression symptoms. The literature suggests that the relationship between OC and depression is mediated by Effort-Reward-Imbalance (ERI), burnout and physical pain. This study tested a two-step mediation effect between OC and depression by ERI in a first, and burnout and physical pain in a second step using a cohort of German Emergency Medical Technicians (EMTs). Methods: A cross-sectional study was carried out on a volunteer sample of 303 EMTs in Germany. OC and ERI were assessed using the ERI questionnaire, burnout with the Maslach Burnout Inventory, physical pain with the Short Form 36, and depression with the BDI-II. The relationship between these variables was tested using a mediation analysis. Results: We found a partial mediation effect between OC and depression via ERI, burnout (emotional exhaustion, personal accomplishment) and physical pain. The mediation effect of emotional exhaustion is significantly higher than those of depersonalization and physical pain. Conclusions: The partial mediation effect suggests the validity of our model assumptions, but also indicates direct relationships between variables (i.e. OC, ERI and depression). The identification of emotional exhaustion as key mediator implies that prevention and intervention approaches in EMTs should be based on this indicator.

Acute stress affects interoception, the processing and perception of signals from inside the body. In contrast, the effects of chronic stress on interoception remain largely unknown, although chronic stress is a potential risk factor for disorders involving interoceptive alterations. This study aimed at investigating the impact of both acute and chronic stress on two key facets of interoception: interoceptive accuracy (IAc) and interoceptive attention (IAt). The study involved schoolteachers, a population at risk of experiencing moderate to high levels of chronic stress. From an initial sample of 219 schoolteachers, 80 attended the laboratory session, with 68 providing complete data sets. They completed a heartbeat counting task (HCT) and a distraction task (DT) before and after undergoing a socially-evaluated cold pressor test (SECPT) as acute stressor. Heartbeat-evoked potentials (HEPs) served as indicators of cardiac IAt. The SECPT evoked an increase in heart rate, blood pressure and salivary cortisol. Cardiac IAc was unaffected by the SECPT. HEPs were higher while performing the HCT than the DT (indicating cardiac IAt), which was intensified after the SECPT. Notably, SECPT effects on cardiac IAt were reversed in individuals with high levels of self-reported chronic stress, whereas cardiac IAc showed a negative association with cortisol/DHEA ratio in hair. Our findings suggest that acute stress increases attentional resources for processing interoceptive sensations, whereas chronic stress attenuates this effect, while simultaneously increasing the sensory threshold for their perception, which may be a mechanism of somatic symptom generation in stress-related disorders.