Blind individuals' enhanced ability to sense their own heartbeat is related to the thickness of their occipital cortex.

Blindness is associated with heightened sensory abilities, such as improved hearing and tactile acuity. Moreover, recent evidence suggests that blind individuals are better than sighted individuals at perceiving their own heartbeat, suggesting enhanced interoceptive accuracy. Structural changes in the occipital cortex have been hypothesized as the basis of these behavioral enhancements. Indeed, several studies have shown that congenitally blind individuals have increased cortical thickness within occipital areas compared to sighted individuals, but how these structural differences relate to behavioral enhancements is unclear. This study investigated the relationship between cardiac interoceptive accuracy and cortical thickness in 23 congenitally blind individuals and 23 matched sighted controls. Our results show a significant positive correlation between performance in a heartbeat counting task and cortical thickness only in the blind group, indicating a connection between structural changes in occipital areas and blind individuals' enhanced ability to perceive heartbeats.

Enhancing Interoceptive Abilities and Emotional Processing: Effects of HD-tDCS.

BACKGROUND: Interoception, the processing and integration of bodily signals, is crucial for emotional experiences and overall well-being. The interoceptive network, including the somatosensory cortices, has been recognized for its role in interoceptive and emotional processing. High-definition transcranial, direct-current stimulation (HD-tDCS) has been demonstrated to modulate brain activity in the primary somatosensory cortex (S1). Based on those findings, we hypothesized that anodal HD-tDCS over the right S1 would enhance interoceptive abilities and heighten emotional perception. METHODS: Thirty-six healthy adults participated in two sessions separated by at least one week. A 20-min HD-tDCS stimulation (2 mA), and a sham stimulation, were applied in randomized order. Both conditions involved pre-tDCS physical activation by ergometer cycling. Interoceptive abilities were assessed before and after both sessions using a heartbeat-perception and respiratory-load task. Emotional perception was measured using four matched international affective picture system (IAPS) picture sets presented randomly. RESULTS: Active HD-tDCS did not significantly improve interoceptive accuracy, interoceptive emotion evaluation, or interoceptive sensibility. However, a notable increase in cardiac interoceptive awareness was observed after active HD-tDCS. The expected enhancement of emotional processing was not observed. CONCLUSIONS: This study represents the first attempt to modulate interoceptive and emotional processing using HD-tDCS over S1. Although consistent enhancement was not observed, our findings provide insights into the modulation of interoceptive and emotional processes with HD-tDCS, suggesting avenues for further research. Further studies should consider the nuanced effects of stimulation techniques and the complex interplay between interoception and emotion.

Decision-making, interoceptive awareness and mindful attention awareness in male patients with alcohol use disorder.

INTRODUCTION: Decision-making deficits in individuals with alcohol use disorder (AUD) may be partly related to their decreased interoceptive awareness (IA), which is associated with some aspects of mindfulness. METHODS: 52 abstinent male inpatients with AUD (current severity: moderate or severe) and 52 healthy male volunteers performed the heart rate tracking task and a computerised version of the Iowa gambling task (IGT). Trait mindfulness was evaluated with the mindful attention awareness scale (MAAS). RESULTS: Heartbeat perception (HBP), MAAS, and IGT scores of patients with AUD were significantly lower than those of healthy controls. The difference between groups with respect to IGT scores did not remain significant after controlling for the covariates, and HBP scores were linked significantly to the subjects' IGT performance. HBP scores significantly predicted IGT scores of both the overall sample and patients. MAAS scores did not correlate significantly with HBP and IGT scores in either the patient or control group. CONCLUSION: It is possible that IA plays a role in decision-making and decreased interoceptive accuracy is a predictor of impaired decision-making in individuals with AUD. More empirical data are needed to develop a better insight into the relationship between IA and multi-dimensional nature of mindfulness.

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

Background: Behavioral models suggest that strong tension-reduction alcohol-outcome expectancies (TREs) among drinkers should be associated with greater tension reduction after drinking. Yet, the few studies investigating this have found either no relationship or the opposite relationship.Objectives: We sought to explore this relationship by building upon the limitations of past studies and employing a placebo-controlled, within-subject experimental design.Methods: Sixty social drinkers (26 M, 34 F) visited the lab on two occasions spaced one week apart. Each participant was randomly assigned to receive alcoholic drinks targeting a BAC of 0.05% on one testing day and placebo drinks on the other, with the order counter-balanced. On both testing days, participants completed measures of state anxiety and fear both before drinking and following a drinking/absorption period. While completing the self-report measures, participants were anticipating an impending, mildly stressful heartbeat perception task.Results: Multilevel modeling revealed that the more strongly individuals believed that alcohol reduces tension, the less the pharmacologic properties of alcohol did so (p = .02 for the state anxiety outcome measure; p = .001 for the fear outcome measure). This was the case even with anxiety sensitivity - a known predictor of stress-response dampening - controlled for.Conclusions: These results provide further evidence for the paradoxical association of TREs and the dampening of anxiety. Additionally, the findings are consistent with the basis of expectancy challenges that aim to reframe inaccurate TREs among drinkers.

Interoceptive Awareness, Decision-Making and Impulsiveness in Male Patients with Alcohol or Opioid Use Disorder.

BACKGROUND: The present study was prepared on the assumption that interoceptive awareness (IA) and decision-making processes are implicated in addiction, and that somatic feedback plays an important role in decision-making. METHODS: The study participants included 80 abstinent male inpatients with alcohol use disorder (n = 40) or opioid use disorder (n = 40) according to DSM-5 criteria (current severity: moderate or severe), along with 40 healthy male volunteers. All participants performed the heart rate tracking task as an objective physiological performance measure of IA and a computerized version of the Iowa gambling task (IGT) as a validated measure of decision-making. Impulsiveness was assessed using the Barratt Impulsiveness Scale 11 (BIS-11). Craving was evaluated with the Penn Alcohol Craving Scale (PACS) or Substance Craving Scale (SCS). RESULTS: (1) Heartbeat perception (HBP) and IGT scores were similar between the patients with alcohol or opioid addiction, being significantly lower than those in the control group, and the difference remained significant even when controlling for the factors that were significant in bivariate analyses; (2) HBP scores of patients correlated significantly with IGT scores, even when controlling the effect of the related variables; (3) BIS-11 scores of patients negatively correlated significantly with HBP scores and did not correlate significantly with IGT scores; and (4) PACS/SCS scores did not correlate significantly with HBP and IGT scores. CONCLUSIONS: Our findings support the hypothesis that IA and decision-making processes are implicated in addiction and that decreased IA is associated with impaired decision-making.

Preoccupied with the body: mild stress amplifies the relation between rumination and interoception.

Classic and modern emotion theories suggest that the perception of bodily sensations, or interoception, is foundational to emotion processing. The present research examined whether interoception is enhanced among people high in ruminative tendencies, especially under stress. To test this notion, the present research examined the effects of a mild stressor on subjective and objective measures of interoception among people varying in ruminative tendencies. Under conditions of mild stress, rumination was positively associated with self-reported private body consciousness -a marker of interoceptive sensibility- in Study 1 (N = 312) and with heartbeat detection accuracy (especially in the presence of auditory interference) in Study 2 (N = 180). In both studies, rumination was not significantly associated with interoceptive sensibility or accuracy in the absence of stress. These findings suggest that stress-induced amplification of bodily sensations may be important in explaining emotional dysregulation among chronic ruminators.

Sense it and use it: interoceptive accuracy and sensibility in suicide ideators.

BACKGROUND: Interoceptive deficits have been found to be associated with suicidal ideation and behavior. However, an objective measure of interoceptive accuracy has not been investigated in participants with suicide ideation, by now. This study aimed at investigating interoceptive accuracy and sensibility in persons with and without suicide ideation (SI) while controlling for severity of depressive symptoms. METHOD: Ninety-five participants (age: M = 34.8, SD = 11.6, n = 56 female [58.9%]; n = 51 patients with a Major Depressive Disorder and n = 44 healthy participants) were assessed for interoceptive accuracy and sensibility, depression and SI. RESULTS: Twenty-five participants (26%) reported SI. They showed interoceptive accuracy comparable to persons without SI (t = -.81, p = .422), but significantly lower interoceptive sensibility. After controlling for severity of depressive symptoms in a hierarchical linear regression analysis, most associations between interoceptive sensibility and SI disappeared. CONCLUSION: Results suggest that suicide ideators do not lack the ability to perceive their own bodily signals but they feel less able to use them in a way that is advantageous for them. Differences between suicide ideators and non-ideators appear to be largely driven by depressive symptoms (depression bias).

Associations between interoceptive sensitivity, intuitive eating, and body mass index in patients with anorexia nervosa and normal-weight controls.

Reduced perception of bodily signals and low levels of intuitive eating have been reported in patients with anorexia nervosa (AN) compared with normal-weight individuals. However, findings have been inconsistent and treatment progress might account for some of these inconsistencies. Thirty-seven inpatients with AN and 39 normal-weight controls completed a heartbeat perception task and the Intuitive Eating Scale-2. Patients with AN reported lower intuitive eating than controls, whereas interoceptive sensitivity did not differ between groups. Higher interoceptive sensitivity was related to higher intuitive eating across both groups. In patients with AN, both higher interoceptive sensitivity and intuitive eating correlated with the number of days in the hospital and with higher body mass index (BMI), when controlling for BMI at admission. These relationships suggest that interoceptive sensitivity and intuitive eating improve during treatment. Future research should determine whether these improvements promote weight gain or follow it.

Diminished Interoceptive Awareness in Fibromyalgia Syndrome.

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

Further Evidence for an External Focus of Attention in Running: Looking at Specific Focus Instructions and Individual Differences.

Although attentional focusing in sports has been broadly investigated, the findings vary when it comes to endurance sports. This study provides a comparison between relevant foci in the literature of running economy. These include two internal foci-one addressing automated processes (running movement) and the other nonautomated processes (internal body signals and perceived exertion), an external focus (video) and a control condition. Furthermore, we investigated the influence of interoceptive sensitivity on oxygen consumption within the different attention conditions. Thirty recreational runners performed a four 6-min run at moderate intensity consisting of the four counterbalanced conditions. Running economy was assessed by spiroergometry, and interoception was measured using a heartbeat tracking task. Results revealed a significantly better running economy for the external focus of attention compared with all other conditions. No significant correlations were observed between the heartbeat perception score and oxygen consumption in any condition.

Baseline heartbeat perception accuracy and short-term outcome of brief cognitive-behaviour therapy for panic disorder with agoraphobia.

BACKGROUND: Increased heartbeat perception accuracy (HBP-accuracy) may contribute to the pathogenesis of Panic Disorder (PD) without or with Agoraphobia (PDA). Extant research suggests that HBP-accuracy is a rather stable individual characteristic, moreover predictive of worse long-term outcome in PD/PDA patients. However, it remains still unexplored whether HBP-accuracy adversely affects patients' short-term outcome after structured cognitive behaviour therapy (CBT) for PD/PDA. AIM: To explore the potential association between HBP-accuracy and the short-term outcome of a structured brief-CBT for the acute treatment of PDA. METHOD: We assessed baseline HBP-accuracy using the "mental tracking" paradigm in 25 consecutive medication-free, CBT-naive PDA patients. Patients then underwent a structured, protocol-based, 8-session CBT by the same therapist. Outcome measures included the number of panic attacks during the past week, the Agoraphobic Cognitions Questionnaire (ACQ), and the Mobility Inventory-Alone subscale (MI-alone). RESULTS: No association emerged between baseline HBP-accuracy and posttreatment changes concerning number of panic attacks. Moreover, higher baseline HBP-accuracy was associated with significantly larger reductions in the scores of the ACQ and the MI-alone scales. CONCLUSION: Our results suggest that in PDA patients undergoing structured brief-CBT for the acute treatment of their symptoms, higher baseline HBP-accuracy is not associated with worse short-term outcome concerning panic attacks. Furthermore, higher baseline HBP-accuracy may be associated with enhanced therapeutic gains in agoraphobic cognitions and behaviours.

Being watched: the effect of social self-focus on interoceptive and exteroceptive somatosensory perception.

We become aware of our bodies interoceptively, by processing signals arising from within the body, and exteroceptively, by processing signals arising on or outside the body. Recent research highlights the importance of the interaction of exteroceptive and interoceptive signals in modulating bodily self-consciousness. The current study investigated the effect of social self-focus, manipulated via a video camera that was facing the participants and that was either switched on or off, on interoceptive sensitivity (using a heartbeat perception task) and on tactile perception (using the Somatic Signal Detection Task (SSDT)). The results indicated a significant effect of self-focus on SSDT performance, but not on interoception. SSDT performance was not moderated by interoceptive sensitivity, although interoceptive sensitivity scores were positively correlated with false alarms, independently of self-focus. Together with previous research, our results suggest that self-focus may exert different effects on body perception depending on its mode (private versus social). While interoception has been previously shown to be enhanced by private self-focus, the current study failed to find an effect of social self-focus on interoceptive sensitivity, instead demonstrating that social self-focus improves exteroceptive somatosensory processing.

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.

Heart is deceitful above all things: Threat expectancy induces the illusory perception of increased heartrate.

It has been suggested that our perception of the internal milieu, or the body's internal state, is shaped by our beliefs and previous knowledge about the body's expected state, rather than being solely based on actual interoceptive experiences. This study investigated whether heartbeat perception could be illusorily distorted towards prior subjective beliefs, such that threat expectations suffice to induce a misperception of heartbeat frequency. Participants were instructed to focus on their cardiac activity and report their heartbeat, either tapping along to it (Experiment 1) or silently counting (Experiment 2) while ECG was recorded. While completing this task, different cues provided valid predictive information about the intensity of an upcoming cutaneous stimulation (high- vs. low- pain). Results showed that participants expected a heart rate increase over the anticipation of high- vs. low-pain stimuli and that this belief was perceptually instantiated, as suggested by their interoceptive reports. Importantly, the perceived increase was not mirrored by the real heart rate. Perceptual modulations were absent when participants executed the same task but with an exteroceptive stimulus (Experiment 3). The findings reveal, for the first time, an interoceptive illusion of increased heartbeats elicited by threat expectancy and shed new light on interoceptive processes through the lenses of Bayesian predictive processes, providing tantalizing insights into how such illusory phenomena may intersect with the recognition and regulation of people's internal states.

Changes in interoceptive accuracy related to emotional interference in somatic symptom disorder.

OBJECTIVE: The somatic symptom disorder (SSD) is characterized by one or more distressing or disabling somatic symptoms accompanied by an excessive amount of time, energy and emotion related to the symptoms. These manifestations of SSD have been linked to alterations in perception and appraisal of bodily signals. We hypothesized that SSD patients would exhibit changes in interoceptive accuracy (IA), particularly when emotional processing is involved. METHODS: Twenty-three patients with SSD and 20 healthy controls were recruited. IA was assessed using the heartbeat perception task. The task was performed in the absence of stimuli as well as in the presence of emotional interference, i.e., photographs of faces with an emotional expression. IA were examined for correlation with measures related to their somatic symptoms, including resting-state heart rate variability (HRV). RESULTS: There was no significant difference in the absolute values of IA between patients with SSD and healthy controls, regardless of the condition. However, the degree of difference in IA without emotional interference and with neutral facial interference was greater in patients with SSD than in healthy controls (p = 0.039). The IA of patients with SSD also showed a significant correlation with low-frequency HRV (p = 0.004) and high-frequency HRV (p = 0.007). CONCLUSION: SSD patients showed more significant changes in IA when neutral facial interference was given. These results suggest that bodily awareness is more affected by emotionally ambiguous stimuli in SSD patients than in healthy controls.

More of myself: manipulating interoceptive awareness by heightened attention to bodily and narrative aspects of the self.

Psychology distinguishes between a bodily and a narrative self. Within neuroscience, models of the bodily self are based on exteroceptive sensorimotor processes or on the integration of interoceptive sensations. Recent research has revealed interactions between interoceptive and exteroceptive processing of self-related information, for example that mirror self-observation can improve interoceptive awareness. Using heartbeat perception, we measured the effect on interoceptive awareness of two experimental manipulations, designed to heighten attention to bodily and narrative aspects of the self. Participants gazed at a photograph of their own face or at self-relevant words. In both experimental conditions interoceptive awareness was significantly increased, compared to baseline. Results show that attention to narrative aspects of self, previously regarded as relying on higher-order processes, has an effect similar to self-face stimuli in improving interoceptive awareness. Our findings extend the previously observed interaction between the bodily self and interoception to more abstract amodal representations of the self.

Intuitive eating is associated with interoceptive sensitivity. Effects on body mass index.

Intuitive eating is relevant for adaptive eating, body weight and well-being and impairments are associated with dieting and eating disorders. It is assumed to depend on the ability to recognize one's signs of hunger and fullness and to eat accordingly. This suggests a link to the individual ability to perceive and processes bodily signals (interoceptive sensitivity, IS) which has been shown to be associated with emotion processing and behavior regulation. This study was designed to clarify the relationships between IS as measured by a heartbeat perception task, intuitive eating and body mass index (BMI) in N=111 healthy young women. Intuitive eating was assessed by the Intuitive Eating Scale (IES) with three facets, reliance on internal hunger and satiety cues (RIH), eating for physical rather than emotional reasons (EPR), and unconditional permission to eat when hungry (UPE). IS was not only positively related to total IES score and RIH and EPR, and negatively predicted BMI, but also proved to fully mediate the negative relationship between RIH, as well as EPR and BMI. Additionally, the subjective appraisal of one's interoceptive signals independently predicted EPR and BMI. IS represents a promising mechanism in research on eating behavior and body weight.

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.

Embodied feelings-A meta-analysis on the relation of emotion intensity perception and interoceptive accuracy.

Emotion theories emphasize the relevance of (predicted) bodily changes for the construction of one's own emotions and an extensive overlap of brain regions involved during emotion intensity perception and somatosensory processing. The ability to accurately perceive bodily changes and its impact on the perception of emotion intensity has been studied for at least 40 years. The results of previous studies were summarized in a meta-analysis to examine how closely interoceptive accuracy and emotion intensity are related. After a systematic literature search, 4036 studies were screened for eligibility. Only studies assessing adults from general population samples were considered. Samples recruited to examine mental disorders or neurological conditions were excluded. Thirty studies with a quantifiable measure for the relation of interoceptive accuracy and emotion intensity perception were included in the meta-analysis. Interoceptive accuracy was significantly related with emotion intensity perception, when emotions were experimentally induced (k= 22, r= 0.15). However, the relationship was only found when IAPS images (k= 9, r= 0.33) or facial expressions (k= 3, r= 0.24) were used for emotion induction. No significant relation was found in studies without emotion induction (k= 19, r = -0.007). There was considerable bias, varying dependent on bias assessment method, study protocol and examined risk of bias dimension. We discuss the impact of differences in study protocols, review the operationalization of interoceptive accuracy critically and derive directions for future research.

Mediterranean diet, interoception and mental health: Is it time to look beyond the 'Gut-brain axis'?

OBJECTIVE: A Mediterranean style diet (i.e., high in fruit, vegetables, fish, pulses, and wholegrains) is said to benefit psychological health. Many low-level interoceptive processes, such as those involved in the 'gut-brain' axis, are suggested to play a mechanistic role in in this relationship. However, interoceptive sensations in other domains, and at higher hierarchical levels of abstraction, have hitherto been overlooked. One domain often studied in relation to psychological health is cardioception. Therefore, we examined whether the Mediterranean diet was associated with first-order perceptual and second-order metacognitive cardioception. METHODS: Participants completed the Heartbeat Detection Task, the Heartbeat Counting Task, and the EPIC-Norfolk Food Frequency Questionnaire from which diet was quantified. RESULTS: Adherence to a Mediterranean style diet was associated with higher cardioceptive accuracy (i.e., perceptual performance) across both tasks. In addition, those consuming a Mediterranean diet had a better ability to detect errors in first order perceptual performance, and a lower prediction error (the magnitude of the difference between accuracy and confidence). DISCUSSION: These findings indicated that deepening our understanding of how interoceptive processes beyond the 'gut-brain' axis are shaped by diet could deepen our understanding of the link between diet and mental health and wellbeing.