Cardiac Interoception Research Articles

Functional Movement Disorder Is Associated with Abnormal Interoceptive Brain Activity: A Task-based Functional MRI Study.

Aberrant interoceptive processing has been hypothesized to contribute to the pathophysiology of functional neurological disorder, although findings have been inconsistent. Here, we utilized functional magnetic resonance imaging (fMRI) to examine neural correlates of interoceptive attention - the conscious focus and awareness of bodily sensations - in functional movement disorder (FMD). We used voxelwise analyses to compare blood oxygenation level-dependent responses between 13 adults with hyperkinetic FMD and 13 healthy controls (HCs) during a task requiring attention to different bodily sensations and to an exteroceptive stimulus. Additionally, we examined between-group differences in self-reported measures of interoception and evaluated their relationship with neural activity. Interoceptive conditions (heartbeat, stomach and 'body', indicating sensations from the body part or limb affected in FMD participants) activated a network involving the precuneus, the posterior cingulate cortex (PCC) and caudate nucleus (CN) bilaterally, and the right anterior insula (aINS) (p <0.05, corrected). Group differences in brain activity were mainly driven by processing of disease-related interoceptive signals, which in the FMD group was associated with a broader neural activation than monitoring gastric interoception, while no group differences were detected during cardiac interoception. Differences based on interoceptive focus (body vs heartbeat and stomach) between FMD subjects and HCs were found in PCC, CN, angular gyrus, thalamus, and in the mid-insula (p <0.05, corrected). This is, to our knowledge, the first study showing that FMD is associated with abnormal interoceptive processing in regions involved in monitoring body state, attentional focus, and homeostatic inference.

Investigating psychobiological causes and mechanisms in functional seizures and functional motor symptoms: Study protocol.

Advances have been made in understanding the aetiology of functional neurological disorder (FND); however, its pathophysiological mechanisms have not been definitively demonstrated. Evidence suggests interacting roles for altered emotional processing and interoception, elevated autonomic arousal, and dissociation, but there is limited evidence demonstrating their causal influence on specific FND symptoms. Our superordinate aim is to elucidate potentially shared and distinct aetiological factors and mechanisms in two common FND subtypes, functional seizures (FS) and functional motor symptoms (FMS). This study has a multimodal, mixed between- and within-groups design. The target sample is 50 individuals with FS, 50 with FMS, 50 clinical controls (anxiety/depression), and 50 healthy controls. Potential aetiological factors (e.g., adverse life events, physical/mental health symptoms, dissociative tendencies, interoceptive insight/sensibility) will be assessed with a detailed medical history interview and self-report questionnaires. A laboratory session will include a neurocognitive battery, psychophysiological testing, cardiac interoception and time estimation tasks and an isometric handgrip task. A subsample will undergo magnetic resonance imaging, including structural, resting-state and task-based scans combined with psychophysiological recording. Remote monitoring with ecological momentary assessment and wearables will measure variability in FND symptoms and their potential predictors/correlates for ≥2 weeks in patients' daily lives. Longitudinal follow-ups at 3, 6, and 12-months will monitor longer-term outcomes in the clinical groups. This study employs multimodal research methods to rigorously examine several putative mechanisms in FND, at subjective/experiential, behavioural, and physiological levels. The study will test causal hypotheses about the role of altered emotional processing, autonomic arousal, dissociation and interoception in the initiation or exacerbation of FND symptoms, directly comparing these processes in FS and FMS to healthy and clinical controls. This is the first study of its kind, with potential to reveal important targets for prevention and treatment of FND in future.

Cardiac interoception in the museum: A novel measure of experience.

Interoception is the perception of the body's internal signals in response to various external and internal stimuli. The present study uses a novel method adapted from the CARdiac Elevation Detection Task to examine cardiac interoception objectively and subjectively in a unique context-in the presence of art. Self-report questionnaires were used to measure subjective interoceptive awareness, subjective interoceptive accuracy, and aesthetic appreciation. For objective interoceptive accuracy and sensibility, a wearable device (Shimmer) measured heart rate (HR) and connected to a mobile application to prompt two questions: "Is your heart beating faster than usual?" and "How confident are you in your previous response?" Participants explored an art gallery for 40 minutes while the Shimmer measured their HR and randomly prompted them to answer the questions. Using a Generalized Estimating Equation model, interoceptive sensibility was not found to predict the odds of submitting a correct response. It was also found that art does not improve participants' perceptions of their HR. Finally, there was no relation between aesthetic appreciation and subjective or objective cardiac interoception. Despite lack of statistical significance, the current study's method presents an improved method by examining interoceptive accuracy in the moment under ecological conditions. To date, findings and methods used in interoception are inconsistent or flawed; the value in the current study lies in the development and demonstration of a method to examine how the environment influences the body and self-awareness across a wide variety of contexts, thereby offering a possible standardized measure of interoception for investigators to adopt.

The duration discrimination respiratory task: A new test to measure respiratory interoceptive accuracy.

Interoception, which refers to the perception of body's internal state, is implicated in emotional processes and psychopathological disorders. Over the last decades, different tools have been developed to measure interoceptive accuracy, or the ability to accurately perceive physiological signals. Most of these tools have focused on cardiac interoception, but respiratory interoception has been less investigated due to the more complex and less portable equipment required. In this study, we suggest a new duration discrimination respiratory (DDR) task that does not require complex equipment. Using an adaptive staircase procedure, this task aims to determine an individual's ability to detect exhalation longer than their resting reference duration. One hundred and twenty-three healthy subjects completed the DDR task, an interoceptive task of heart rate discrimination, and filled out questionnaires on interoceptive awareness (Multidimensional Assessment of Interoceptive Awareness), alexithymia (Toronto Alexithymia Scale [TAS]), affects (Positive and Negative Affect Scale [PANAS]), and anamnestic. Results demonstrated a good internal consistency (Cronbach's alpha = .93) of the DDR task. On average, subjects needed 99.22% (SD = 36.38) of their reference exhalation time in addition to reference exhalation to detect a prolonged exhalation. Higher self-reported fitness levels, not counting during the DDR task and lower difficulty in describing feelings (TAS subscale), predicted higher respiratory discrimination duration. In conclusion, this study demonstrates the utility of the DDR task as a valid measure of interoception.

Aberrant Cardiac Interoception in Psychosis.

There is mounting evidence that cardiac interoception, the perception of one's heartbeat, is central to affective experiences. It has been proposed that symptoms of psychosis could arise from interoceptive dysfunction. Here we hypothesized that people with psychotic disorders would have a specific impairment in cardiac interoception, over and above broader perceptual deficits. 43 adults with a history of psychosis (31 schizophrenia, 12 schizoaffective disorder) and 41 matched control participants completed a heart rate discrimination task. Participants responded to whether they perceived a sequence of auditory tones to be faster or slower than their heart rate. By trialing a range of auditory tone rates, we estimated a threshold for each participant, the difference between perceived heart rate and actual heart rate. To test whether differences were specific to interoception, participants completed an exteroceptive control condition, testing their discrimination of the rate of 2 sets of audible sounds instead of heart rate. Participants with a history of psychosis had greater absolute differences between perceived and actual heart rate, indicating over- or under-estimation of heart rate compared to healthy controls. This difference was specific to the interoceptive condition, and not explained by group differences in exteroceptive perception. Psychotic disorders are associated with misestimation of heart rate. Further research may elucidate whether interoceptive abnormalities contribute to specific symptoms such as somatic delusions or affective features, and whether interoception could be a treatment target in psychotic disorders.

Alcohol effects on interoception shape expectancies and subjective effects: a registered report using the heart rate discrimination task.

Alcohol acutely impacts interoceptive processes, which in turn affect the perception of alcohol effects and the development of alcohol expectancies. However, previous research is limited by the tools used to measure cardiac interoception and subjective alcohol effects. This registered report proposes a re-examination of previous findings using a state-of-the-art measure of interoceptive capacity, the heart rate discrimination task, and measurements of subjective alcohol effects across both ascending and descending limbs. In a double-blind, placebo-controlled experiment, n = 36 participants were given 0.4g/kg of ethanol, and a baseline measure of alcohol expectancies was obtained. Changes in interoceptive capacity after beverage administration, along with measures of light-headedness, mood, and biphasic alcohol effects, were assessed over two sessions. As registered in this secondary data analysis, alcohol was expected to acutely impact different indices of interoceptive capacity, and those changes were hypothesized to correlate with subjective alcohol effects and expectancies. Analyses were conducted only following in-principle acceptance. Alcohol-induced changes in interoceptive capacity predicted the development of light-headedness, stimulation, and negative mood. Changes in interoceptive capacity were also correlated with negative alcohol expectancies, as measured 2 weeks prior to the experiment. These effects were unique to the interoceptive condition, as null effects were observed in an exteroceptive control task. This report offers a replication of key previous findings that alcohol impacts interoceptive processes to shape the detection of subjective alcohol effects. We propose that, through repeated drinking occasions, bodily responses feed into the experience of intoxication, shaping future expectancies about alcohol effects.

Cardiac Contractility Drives Cardiac Interoception

Introduction: Many of the receptors for the exteroceptive senses (e.g. vision, hearing, smell, touch, pain, etc.) are known. Interoception allows us to sense threats to our “milieu interior.” The mechanisms by which threats induce a feeling of anxiety manifested by heart palpitations, shortness of breath (dyspnea), and gastric awareness (queasiness) are unknown. Using photoplethysmography, we reported that individual variation in cardiac interoception, i.e. the ability to feel a change in one’s heartbeat without taking one’s pulse, correlated with contrasts in heart rate and stroke volumes among the population. Hypothesis: Because increases in heart rate and stroke volume raise cardiac contractility, we postulated that stretch activated piezo channels in the heart are responsible for cardiac interoception. Methods: Interoceptive awareness was determined with a ten point Likert scale in which volunteers rated their ability to feel their heartbeat. Interoceptive accuracy was measured by asking subjects to count their heartbeats without taking their pulse over four time intervals in random order. Simultaneously, heart rates were surreptitiously recorded with a two lead electrocardiogram (EKG). Cardiac interoceptive accuracy was calculated using the formula 1/4 Σ [1 − (|EKG measured heartbeats − subjectively reported heartbeats|) / EKG measured heartbeats]. We used 2D speckle tracking ultrasound to measure the relationship between cardiac strain patterns, normalized for heart rate (HR) and body surface area (BSA), and cardiac interoception in 12 resting men and women. We also measured gastric interoception by determining the percent increase in the volume of water some subjects could drink after reporting water satiety. Results: Cardiac interoceptive awareness correlated with interoceptive accuracy ( r = 0.73, p = 0.009). Speckle tracking of cardiac chambers with echocardiography demonstrated that global longitudinal left ventricular (LV) strain correlated with total left ventricular preload (atrial reservoir strain, r = 0.83, p = 0.0009) and early diastolic filling (atrial conduit strain, r = 0.88, p = 0.0002). LV strain also correlated with interoceptive awareness ( r = 0.58, p = 0.046). When stratified, individuals with the highest interoceptive accuracy (n = 6), compared to those with the lowest interoceptive accuracy (n = 6), had less LV strain, [values expressed as (percent change/BSA)*HR ± S.E.M., 828 ± 81 vs. 582 ± 47, p = 0.026]. Cardiac interoceptive awareness also correlated with gastric interoception accuracy, (n = 6) r = 0.90, p = 0.015. Conclusions: Changes in the activation of cardiac stretch receptors by cardiac filling and contractility could modify interoceptive awareness in men and women at rest. Contrasts in stretch receptor activation in other contractile organs (e.g. stomach) could explain variation in interoceptive awareness in the population. Henry M. Jackson Foundation for the Advancement of Military Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A framework for quantifying the coupling between brain connectivity and heartbeat dynamics: Insights into the disrupted network physiology in Parkinson's disease.

Parkinson's disease (PD) often shows disrupted brain connectivity and autonomic dysfunctions, progressing alongside with motor and cognitive decline. Recently, PD has been linked to a reduced sensitivity to cardiac inputs, that is, cardiac interoception. Altogether, those signs suggest that PD causes an altered brain-heart connection whose mechanisms remain unclear. Our study aimed to explore the large-scale network disruptions and the neurophysiology of disrupted interoceptive mechanisms in PD. We focused on examining the alterations in brain-heart coupling in PD and their potential connection to motor symptoms. We developed a proof-of-concept method to quantify relationships between the co-fluctuations of brain connectivity and cardiac sympathetic and parasympathetic activities. We quantified the brain-heart couplings from electroencephalogram and electrocardiogram recordings from PD patients on and off dopaminergic medication, as well as in healthy individuals at rest. Our results show that the couplings of fluctuating alpha and gamma connectivity with cardiac sympathetic dynamics are reduced in PD patients, as compared to healthy individuals. Furthermore, we show that PD patients under dopamine medication recover part of the brain-heart coupling, in proportion with the reduced motor symptoms. Our proposal offers a promising approach to unveil the physiopathology of PD and promoting the development of new evaluation methods for the early stages of the disease.

Delving into the relationship between regular physical exercise and cardiac interoception in two cross-sectional studies

Cardiac interoception, the ability to sense and process cardiac afferent signals, has been shown to improve after a single session of acute physical exercise. However, it remains unclear whether repetitive engagement in physical exercise over time leads to long-term changes in cardiac interoceptive accuracy. It is also unknown whether those changes affect the neural activity associated with the processing of afferent cardiac signals, assessed by the heart-evoked potential (HEP). In this study, we aimed to investigate this hypothesis through two cross-sectional studies, categorizing participants as active or inactive based on physical fitness (Study I; N = 45) or self-reported physical activity levels (Study II; N = 60). Interoception was assessed at rest using the HEP (Studies I and II), the Heartbeat Counting task (Study II), and the Rubber Hand Illusion (RHI) (Study II). Study I showed strong evidence of better cardiovascular fitness in the active group than in the inactive group as well as robust between-group differences in electrocardiogram (ECG) recordings. Study 2 replicated the clear differences in ECG as a function of regular physical activity. Those results were expected due to clear differences in physical activity habits. In contrast, our analysis revealed no robust differences between groups across cardiac interoception tasks and the RHI, although the direct relevance of these measures to interoception remains under investigation. In sum, our results do not provide convincing evidence to support a strong version of the notion that regular physical exercise is associated with an enhanced in cardiac interoception.

Acute fasting modulates autonomic nervous system function and ambulatory cardiac interoception

Intermittent fasting has been associated with diverse physical and psychological health benefits. According to previous research, fasting-induced alterations in psychophysiological functioning should facilitate the accurate detection of an internal bodily signal (like the heart), which is referred to as interoceptive accuracy. In two within-subjects studies we aimed to examine whether an intermittent fasting protocol (i) evokes distinct autonomic nervous system changes in the laboratory and (ii) improves (objectifiable) interoceptive accuracy and sensibility (i.e., the subjective belief in perceiving bodily signals) in everyday life. Study 1 (N = 36) found increasing heart rate variability (precisely, the root mean square of successive differences; RMSSD) accompanied by a more vascular than myocardial response following a 16 h fast. Study 2 (N = 40) applied an ecological momentary assessment design including intermittent fasting (8 h normal eating followed by 16 h fasting) and normal eating (24 h normal eating) for three consecutive days each. Findings suggested a tendency toward higher interoceptive accuracy and sensibility during the fasting regimen, which was particularly pronounced in individuals exhibiting lower RMSSD. Together, findings suggest that (short-term) fasting seems to facilitate momentary attention to organismic cues due to alterations in autonomic nervous system function.

Heartbeat-evoked neural response abnormalities in generalized anxiety disorder during peripheral adrenergic stimulation.

Hyperarousal symptoms in generalized anxiety disorder (GAD) are often incongruent with the observed physiological state, suggesting that abnormal processing of interoceptive signals is a characteristic feature of the disorder. To examine the neural mechanisms underlying interoceptive dysfunction in GAD, we evaluated whether adrenergic modulation of cardiovascular signaling differentially affects the heartbeat-evoked potential (HEP), an electrophysiological marker of cardiac interoception, during concurrent electroencephalogram and functional magnetic resonance imaging (EEG-fMRI) scanning. Intravenous infusions of the peripheral adrenergic agonist isoproterenol (0.5 and 2.0 micrograms, μg) were administered in a randomized, double-blinded and placebo-controlled fashion to dynamically perturb the cardiovascular system while recording the associated EEG-fMRI responses. During the 0.5 μg isoproterenol infusion, the GAD group (n = 24) exhibited significantly larger changes in HEP amplitude in an opposite direction than the healthy comparison (HC) group (n = 24). In addition, the GAD group showed significantly larger absolute HEP amplitudes than theHC groupduring saline infusions, when cardiovascular tone did not increase. No significant group differences in HEP amplitude were identified during the 2.0 μg isoproterenol infusion. Using analyzable blood oxygenation level-dependent fMRI data from participants with concurrent EEG-fMRI data (21 GAD and 21 HC), we found that the aforementioned HEP effects were uncorrelated with fMRI signals in the insula, ventromedial prefrontal cortex, dorsal anterior cingulate cortex, amygdala, and somatosensory cortex, brain regions implicated in cardiac signal processing in prior fMRI studies. These findings provide additional evidence of dysfunctional cardiac interoception in GAD and identify neural processes at the electrophysiological level that may be independent from blood oxygen level-dependent responses during peripheral adrenergic stimulation.

Heartbeat-evoked potentials following voluntary hyperventilation in epilepsy patients: respiratory influences on cardiac interoception.

Current evidence indicates a modulating role of respiratory processes in cardiac interoception, yet whether altered breathing patterns influence heartbeat-evoked potentials (HEP) remains inconclusive. Here, we examined the effects of voluntary hyperventilation (VH) as part of a clinical routine examination on scalp-recorded HEPs in epilepsy patients (N = 80). Using cluster-based permutation analyses, HEP amplitudes were compared across pre-VH and post-VH conditions within young and elderly subgroups, as well as for the total sample. No differences in the HEP were detected for younger participants or across the full sample, while an increased late HEP during pre-VH compared to post-VH was fond in the senior group, denoting decreased cardiac interoceptive processing after hyperventilation. The present study, thus, provides initial evidence of breathing-related HEP modulations in elderly epilepsy patients, emphasizing the potential of HEP as an interoceptive neural marker that could partially extend to the representation of pulmonary signaling. We speculate that aberrant CO2-chemosensing, coupled with disturbances in autonomic regulation, might constitute the underlying pathophysiological mechanism behind the obtained effect. Available databases involving patient records of routine VH assessment may constitute a valuable asset in disentangling the interplay of cardiac and ventilatory interoceptive information in various patient groups, providing thorough clinical data to parse, as well as increased statistical power and estimates of effects with higher precision through large-scale studies.

Comparison of methods for cardiac interoception self-assessment

Aim. Interoception reflects the perception, integration and modulation of visceral signals. Currently, there is no established universal approach to cardiac interoception assessment allowing its inclusion in the diagnostic protocol for various diseases. The aim was to compare three tests of interoception self-assessment based on heart palpitations within one day in healthy subjects.Material and methods. Eighty healthy volunteers took part in the study. To assess cardiac interoception, a test with button pushes at the moment of palpitations, a feedback test in the form of synchronous and asynchronous sound signals, a heartbeat counting task at specified time intervals were conducted with simultaneous electrocardiographic recording. The obtained data were compared with each other (Wilcoxon test). Its pairwise dependence (Spearman coefficient) and dependence on body parameters (sex, age, body mass index, fat mass, anxiety) were assessed (univariate linear regression).Results. The accuracy of the heartbeat counting task turned out to be significantly higher than in the button- pressing test (p=0,005). However, both estimates correlate with each other (r=0,66, p=0,003). A positive dependence of test accuracy on sex was found for the heartbeat counting task (p=0,021) and a negative dependence on fat mass for button- pressing task (p=0,032).Conclusion. The study found that volunteers' estimates of heartbeat accuracy varied across tests and were also associated with sex and body composition. The heart rate counting task and the button- pressing task are the most suitable for interoception assessment.

Cardiac interoception in Anorexia Nervosa: A resting-state heartbeat-evoked potential study.

A deficit in interoception - the ability to perceive, interpret and integrate afferent signals about the physiological state of the body - has been shown in Anorexia Nervosa (AN), and linked to altered hunger sensations, body dysmorphia, and abnormal emotional awareness. The present high-density electroencephalography (hdEEG) study aims to assess cardiac interoception in AN and to investigate its neural correlates, using an objective neurophysiological measure. Heartbeat-evoked potentials (HEPs) were computed from 5min of resting-state EEG and electrocardiogram (ECG) data and compared between individuals with AN (N=22) and healthy controls (HC) (N=19) with waveform, topographic, and source imaging analyses. Differences in the cortical representation of heartbeats were present between AN and HC at a time window of 332-348ms after the ECG R-peak. Source imaging analyses revealed a right-sided hypoactivation in AN of brain regions linked to interoceptive processing, such as the anterior cingulate and orbitofrontal areas. To the best of our knowledge, this is the first study using hdEEG to localise the underlying sources of HEPs in AN. Results point to altered interoceptive processing during resting-state in AN. As our participants had a short duration of illness, this might not be the consequence of prolonged starvation. Interventions targeted at interoception could provide an additional tool to facilitate recovery.

Is That My Heartbeat? Measuring and Understanding Modality-Dependent Cardiac Interoception in Virtual Reality.

Measuring interoception ('perceiving internal bodily states') has diagnostic and wellbeing implications. Since heartbeats are distinct and frequent, various methods aim at measuring cardiac interoceptive accuracy (CIAcc). However, the role of exteroceptive modalities for representing heart rate (HR) across screen-based and Virtual Reality (VR) environments remains unclear. Using a PolarH10 HR monitor, we develop a modality-dependent cardiac recognition task that modifies displayed HR. In a mixed-factorial design (N=50), we investigate how task environment (Screen, VR), modality (Audio, Visual, Audio-Visual), and real-time HR modifications ( ±15%, ±30%, None) influence CIAcc, interoceptive awareness, mind-body measures, VR presence, and post-experience responses. Findings showed that participants confused their HR with underestimates up to 30%; environment did not affect CIAcc but influenced mind-related measures; modality did not influence CIAcc, however including audio increased interoceptive awareness; and VR presence inversely correlated with CIAcc. We contribute a lightweight and extensible cardiac interoception measurement method, and implications for biofeedback displays.

Heart activity perception: narrative review on the measures of the cardiac perceptual ability

Measures of cardiac perceptual ability (also called cardiac accuracy) are methods of cardiac interoception, the perception of bodily sensation related to heart activity. This narrative review aims to provide an overview of these methods. We differentiate between three main measurement types: (1) change detection, i.e., when the task is to notice the change in the heart rate; also called: heart rate perception tasks, (2) discrimination tasks, i.e., when the task is to compare the internal sensations with external signal(s); also called: heartbeat detection tasks and (3) tracking tasks, i.e., when the task is to follow and report heartbeats via tapping or counting. We describe some of the new methods under “mixed methods,” as they share features with more than one of the large measurement types described above. Specific measures differ in various aspects, such as their focus (heart rhythm vs. single beats), their sensitivity to non-conscious sensations and the calculated indices (e.g., whether significance level by hypothesis test is provided). When a measure of cardiac perceptual ability is chosen, it is advisable to take its characteristics into consideration in light of the planned research.

Fear of physical activity relates to cardiac interoception and symptom distress in patients with chronic heart failure

BackgroundPatients with chronic heart failure often experience symptoms during physical activity, such as shortness of breath and tachycardia, which may result in fear of physical activity (FoPA). This study tested whether interoception (i.e., the perception of body sensations) and symptom distress (i.e., negative appraisal of symptoms) are associated with FoPA in outpatients with chronic heart failure. MethodFoPA was assessed with the Fear of Activities in Situations (FActS) in patients with diagnosed heart failure and healthy controls. A heartbeat tracking task and self-reports were used to assess interoceptive accuracy and interoceptive attention in patients and controls. Heart failure-related distress was assessed using ratings of symptom and treatment burden in patients. Multiple regression models were calculated to determine associations with continuous FoPA scores. ResultsPatients with low FoPA perceived their heartbeats more accurately than patients with high FoPA and healthy controls. Interoceptive accuracy and symptom distress explained almost half of the variance in FoPA, after adjustments for sex and disease severity, in patients with heart failure. ConclusionsIn patients inaccurate interoception and symptom distress were associated with high FoPA, independent of heart failure severity. The perception and appraisal of cardiac arousal and symptoms during physical activity deserve further attention to develop interventions to reduce FoPA in patients with heart failure. ClinicalTrials.gov IdentifierNCT03119298.

Reduced concentration performance and heartbeat-evoked potential in individuals with a history of a SARS-CoV-2 infection

The goal of characterizing long-term psychological and neural consequences of a SARS-CoV-2 infection has recently gained importance. Here, we examined the effect of a prior SARS-CoV-2 infection on neural markers of exteroceptive (P300) and interoceptive (heartbeat-evoked potential; HEP) signal processing, as well as on neuropsychological tests of attention, inhibition and episodic memory, in 23 adults with a self-reported history of SARS-CoV-2 infection versus 23 healthy controls. We found that the group with a prior infection showed decreased HEP (but not P300) amplitudes, as well as reduced attention/concentration performance. These results suggest that SARS-CoV-2 may damage neural structures of cardiac interoception, thereby potentially contributing to cognitive and psychological long-term deficits. Modulations of interoceptive processing after a SARS-CoV-2 infection are thus a promising target for future research.

Dynamic heartbeat tracking beyond the laboratory: Introducing the novel Graz Ambulatory Interoception Task (GRAIT)

We present a novel ambulatory method, the Graz Ambulatory Interoception Task (GRAIT), to assess the accuracy of interoceptive beliefs (AccIB). This method captures both between- and within-person variations of AccIB by having participants counting perceived heartbeats in daily life. Reliability analyses showed high between-person (RkR = 0.99) and moderate within-person reliability (RCn = 0.62). Validity was supported by associations with an established laboratory task (r = 0.87). Within-person associations revealed that interoceptive sensibility, heart rate variability, and states of low arousal coupled with positive affect were linked to AccIB. Study 2 replicated these findings and showed a relationship between AccIB and self-control in everyday life, highlighting the importance of cardiac interoception and its relevance for health.

The thermoception task: a thermal imaging-based procedure for measuring awareness of changes in peripheral body temperature.

Although thermal body signals provide crucial information about the state of an organism and changes in body temperature may be a sign of affective states (e.g., stress, pain, sexual arousal), research on thermal awareness is limited. Here we developed a task measuring awareness of changes in peripheral body temperature (thermal interoception) and compared it to the classical heartbeat counting task (cardiac interoception). With an infrared light bulb we delivered stimuli of different temperature intensities to the right hand of 31 healthy participants. Thermal interoceptive accuracy, i.e., the difference between participants' real and perceived change in hand temperature, showed good interindividual variability. We found that thermal interoception did not correlate with (and was generally higher than) cardiac interoception, suggesting that different interceptive channels provide separate contributions to awareness of bodily states. Moreover, the results hint at the great salience of thermal signals and the need for thermoregulation in day-to-day life. Finally, thermal interoceptive accuracy was associated with self-reported awareness of body temperature changes and with the ability to regulate distress by focusing on body sensations. Our task has the potential to significantly increase current knowledge about the role of interoception in cognition and behavior, particularly in social and emotional contexts.NEW & NOTEWORTHY We developed a novel task measuring awareness of changes in peripheral body temperature (i.e., thermal interoception). To avoid tactile confounds present in existing thermoceptive tasks, we used an infrared light bulb to deliver stimuli of different temperature intensities to the hand of participants and asked them to judge the perceived change in their hand temperature. Performance in the task showed good interindividual variability, did not correlate with cardiac interoceptive tasks, and was associated with self-reported thermosensitivity.