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

Heartfelt gaze: Cardiac afferent signals and vagal tone affect gaze perception

Perceiving others' gaze direction is an essential aspect of social interactions. The cone of direct gaze (CoDG) refers to the range within which an observer perceives a gaze as looking directly at them. Previous research has demonstrated that self-relevant exteroceptive cues can widen the CoDG. However, the effect of self-relevant interoceptive information on the CoDG remains unknown. This study investigated the contribution of cardiac afferent signals and vagal tone to the perception of gaze from others. We used a modified gaze discrimination task to synchronize face stimuli with various gaze directions to specific phases of the cardiac cycle. Results revealed that participants with higher heart rate variability (HRV) exhibited a wider CoDG during cardiac systole (when cardiac signals are maximally represented in the brain). However, no effect was observed during cardiac diastole (when cardiac signals are quiescent). Moreover, this effect was independent of individual differences in anxiety levels and autistic traits. These findings are evidence that individuals with greater cardiac vagal control are more sensitive to cardiac afferent signals during systole, which leads to a stronger self-directed perception of others' gaze under transient and ambiguous gaze perception conditions. Our findings highlight the self-referential role of cardiac interoceptive signals in gaze perception and expand our knowledge of interoceptive influences on social judgment.

Interoception in Parkinson's disease: A narrative review and framework for translational research

Parkinson's disease (PD) is the second most common, and the fastest growing, neurodegenerative disease worldwide. Non-motor manifestations, particularly autonomic nervous system dysfunction, are common throughout the disease course, in some cases preceding motor symptom onset by years, and are often more disabling and harder to treat than motor symptoms and contribute significantly to disability. An understudied consequence of autonomic and visceral dysfunction in PD is interoception, the neural processing of internal organ system signals. Interoceptive processes form a foundational body-brain interface, mediating basic homeostatic reflexes and complex physiologic and behavioral adaptive responses to internal perturbations. Emerging evidence exists that interoception is impaired in some individuals with PD, potentially explaining why those who have objective evidence of autonomic dysfunction do not always report typical symptoms. Failure to recognize these impairments may lead to missed opportunities for early intervention, particularly in addressing 'silent' autonomic disturbances (e.g., orthostatic hypotension leading to sudden falls, dysphagia leading to aspiration pneumonia). In this narrative review, we synthesize current findings on the neuroanatomical networks underlying interoception, examine clinical manifestations of interoceptive dysfunction across multiple organ systems in PD, and identify key gaps in knowledge. We propose a translational research framework to enhance early detection, symptom management, and intervention strategies for PD. This framework integrates cognitive, mood, and autonomic dysfunctions with clinical factors (disease stage, duration, motor subtype, levodopa status) to understand interoceptive dysfunction within a translational model. This approach highlights novel opportunities for personalized care and improved therapeutic interventions in PD.

An audit of 12 cases of long COVID following the lightning process intervention examining benefits and harms

To audit the outcomes of patients with long COVID after the lightning process intervention. Retrospective cross-sectional audit. Patients with long COVID were interviewed through telephone regarding their experience and response to the lightning process. Physical, emotional, and overall quality of life; perceived harms of the intervention. None of the 12 participants reported harm from the intervention. 11/12 participants reported being 85% back to normal or more; 8/12 described achieving 85% or greater satisfaction with their emotional, physical, and overall quality of life. 10/12 of the participants reported having heard negative comments about the lightning process but had nonetheless gone ahead with the treatment. This study suggests that the lightning process is a promising and safe intervention for symptoms of long COVID. Primary care clinicians can refer patients for treatment with a high chance of benefit without fear of harm. Randomized, controlled trials are indicated.

The association between interoception and olfactory affective responses

Odors are known to affect an individual's emotions and physiological states. Recent research has revealed that olfaction is linked to the mental representation of internal sensations, known as interoception. However, little research has examined how interoception relates to emotional responses to odors. This research aimed to fill this gap in the literature. We conducted two studies with a total of 548 Japanese women (n = 500 and n = 48 in Studies 1 and 2, respectively). Study 1 used an online survey to assess the relationship between self-reported interoceptive traits and the intensity of positive emotions in response to daily odors. Study 2 examined how self-reported interoceptive traits modulated the arousal ratings of odors presented in the laboratory and the concordance between these perceived arousal ratings and odor-evoked physiological responses. Study 1 confirmed that self-reported interoceptive traits were significant predictors of positive emotional intensity of odors. In Study 2, individuals with high interoceptive measure scores showed concordance between their perceived emotional arousal and the physiological responses associated with that emotion, whereas individuals with low scores did not. These findings suggest that how people perceive their internal sensations contributes to shaping their olfactory affective experiences, thereby broadening the scope of interoception research and aromachology. The practical implications of these findings for the development of commercial fragrances are discussed.

The role of the somatosensory system in the feeling of emotions: a neurostimulation study

Emotional experiences deeply impact our bodily states, such as when we feel 'anger', our fists close and our face burns. Recent studies have shown that emotions can be mapped onto specific body areas, suggesting a possible role of the primary somatosensory system (S1) in emotion processing. To date, however, the causal role of S1 in emotion generation remains unclear. To address this question, we applied transcranial alternating current stimulation (tACS) on the S1 at different frequencies (beta, theta, and sham) while participants saw emotional stimuli with different degrees of pleasantness and levels of arousal. Results showed that modulation of S1 influenced subjective emotional ratings as a function of the frequency applied. While theta and beta-tACS made participants rate the emotional images as more pleasant (higher valence), only theta-tACS lowered the subjective arousal ratings (more calming). Skin conductance responses recorded throughout the experiment confirmed a different arousal for pleasant versus unpleasant stimuli. Our study revealed that S1 has a causal role in the feeling of emotions, adding new insight into the embodied nature of emotions. Importantly, we provided causal evidence that beta and theta frequencies contribute differently to the modulation of two dimensions of emotions-arousal and valence-corroborating the view of a dissociation between these two dimensions of emotions.

Intranasal Oxytocin Improves Interoceptive Accuracy and Heartbeat-Evoked Potentials During a Cardiac Interoceptive Task

BACKGROUND

Interoception represents perception of the internal bodily state, which is closely associated with social/emotional processing and physical health in humans. Understanding the mechanism that underlies interoceptive processing, particularly its modulation, is therefore of great importance. Given the overlap between oxytocinergic pathways and interoceptive signaling substrates in both peripheral visceral organs and the brain, intranasal oxytocin administration is a promising approach for modulating interoceptive processing.

METHODS

Using a double-blind, placebo-controlled, between-participant design, we recruited 72 healthy male participants who performed a cardiac interoceptive task during electroencephalograph and electrocardiograph recording to examine whether intranasal administration of the neuropeptide oxytocin could modulate interoceptive processing. We also collected data in a resting state to examine whether we could replicate previous findings.

RESULTS

The results showed that in the interoceptive task, oxytocin increased interoceptive accuracy at the behavioral level, which was paralleled by larger heartbeat-evoked potential amplitudes in frontocentral and central regions on the neural level. However, there were no significant effects of oxytocin on electroencephalograph or electrocardiograph during resting state.

CONCLUSIONS

These findings suggest that oxytocin may only have a facilitatory effect on interoceptive processing under task-based conditions. Our findings not only provide new insights into the modulation of interoceptive processing via targeting the oxytocinergic system but also provide proof-of-concept evidence for the therapeutic potential of intranasal oxytocin in mental disorders with dysfunctional interoception.

The Association of Emotion Regulation and Somatic Symptoms

OBJECTIVE

People with functional somatic symptoms have difficulties in various stages of the emotion regulation (ER) process. As an adaptive and flexible use of ER strategies is a core tenet of emotional health, having difficulties in this area is often assumed to be the key mechanism behind functional somatic symptoms. Following a dimensional population-based sampling approach, we investigated ER abilities across a broad range of people and tested possible associations with somatic symptom reporting, habitual ER use, and various subclinical constructs (such as alexithymia and anxiety).

METHODS

In a sample of N = 254 persons, somatic symptom distress (Patient Health Questionnaire-15, Hierarchical Taxonomy of Psychopathology somatoform spectrum), trait ER facets (Emotion Regulation Questionnaire, Emotion Reactivity Scale), and the ER abilities (suppression and reappraisal) were assessed. Correlations (frequentist and Bayesian), ANOVAs, and structural equation models were used to analyze the data.

RESULTS

Correlational and structural equation model analyses revealed that general symptom severity (both on the somatoform Hierarchical Taxonomy of Psychopathology and Patient Health Questionnaire-15) was not significantly associated with ER effectiveness, general arousal, or general valence. The sensory components of pain symptoms ( r = -0.708, p = .023) and health anxiety ( r = -0.443, p = .028) were significantly negatively associated with effective ER.

CONCLUSIONS

ER effectiveness seems independent of general somatic symptom distress. We make recommendations for clinical interventions in light of these complex findings.

The neurobiology of interoception and affect

Scholars have argued for centuries that affective states involve interoception, or representations of the state of the body. Yet, we lack a mechanistic understanding of how signals from the body are transduced, transmitted, compressed, and integrated by the brains of humans to produce affective states. We suggest that to understand how the body contributes to affect, we first need to understand information flow through the nervous system's interoceptive pathways. We outline such a model and discuss how unique anatomical and physiological aspects of interoceptive pathways may give rise to the qualities of affective experiences in general and valence and arousal in particular. We conclude by considering implications and future directions for research on interoception, affect, emotions, and human mental experiences.

Randomized trial on the effects of an EMDR intervention on traumatic and obsessive symptoms during the COVID-19 quarantine: a psychometric study

Introduction

It has been suggested that the COVID-19 pandemic was a potentially traumatic occurrence that may have induced generalized anxiety and discomfort, particularly in susceptible populations like individuals with mental illnesses. The therapeutic approach known as eye movement desensitization and reprocessing (EMDR) has been shown to be successful in helping patients process traumatic events and restore wellbeing. Nevertheless, little is known about the precise processes through which EMDR fosters symptom recovery.

Methods

In order to disentangle these issues, we conducted a randomized controlled trial (ClinicalTrials.gov Identifier NCT06110702) with 107 participants who were selected from university hospitals as a sample of investigation. Random assignments were applied to the participants in order to assign them to the experimental and control groups. The experimental group, but not the control group, underwent an 8-week EMDR intervention. Body perception, disgust, and emotions of guilt and shame, as well as mental contamination and posttraumatic and obsessive-compulsive symptoms, were investigated before and after the EMDR intervention.

Results

The EMDR intervention was able to improve all of the variables investigated. Path analysis showed that body perception was able to predict both disgust and emotions of guilt and shame. Disgust was able to predict both mental contamination and obsessive-compulsive symptoms, while guilt and shame were able to predict post-traumatic symptoms.

Conclusions

EMDR is an effective therapy for the treatment of post-traumatic and obsessive symptoms that acts through the promotion of improvement of the emotions of guilt/shame and disgust, respectively. Implications for clinical practice are examined.

Clinical trial registration

https://www.clinicaltrials.gov, identifier NCT06110702.

Modulation of the heartbeat evoked cortical potential by hypnotizability and hypnosis

Hypnotizability is a psychophysiological trait measured by scales and associated with several differences, including interoceptive accuracy and the morpho-functional characteristics of interoception-related brain regions. The aim of the study was to assess whether the amplitude of the heartbeat evoked cortical potential (HEP), a correlate of interoceptive accuracy, differs in participants with low (lows) and high (highs) hypnotizability scores (assessed by the Stanford Hypnotic Susceptibility Scale, Form A) before and after the induction of hypnosis. ECG and EEG were monitored in 16 highs and 15 lows during an experimental session, including open eyes baseline (B), closed eyes relaxation (R), hypnotic induction (IND), neutral hypnosis (NH), and post session baseline (Post). No significant difference was observed between groups and conditions in autonomic variables. The HEP amplitude was lower in highs than in lows at the right parietal site, likely due to hypnotizability related differences in the functional connection between the right insula and parietal cortex. It increased in highs and decreased in lows across the session, possibly due to the highs' preeminently internally directed attention and to the lows' possible disengagement from the task. Since interoception is involved in several cognitive-emotional functions, its hypnotizability related differences may contribute to the variability of experience and behavior in daily life.

Association of Hypnotizability, Interoception, and Emotion

The present scoping review reports the reciprocal relations between hypnotizability, interoception, and emotion. Brain morpho-functional differences may account for the lower interoceptive accuracy, higher interoceptive sensitivity, and different emotional strategies observed in highly hypnotizable participants with respect to medium-to-low hypnotizables. Since interoception is relevant to both physical and mental health and hypnotizability can predict both interoceptive abilities and the efficacy of interoception-based mental training, this allows for the development of new forms of treatment and rehabilitation.

Mapping the mental space of emotional concepts through kinematic measures of decision uncertainty

Emotional concepts and their mental representations have been extensively studied. Yet, some ecologically relevant aspects, such as how they are processed in ambiguous contexts (e.g., in relation to other emotional stimuli that share similar characteristics), are incompletely known. We employed a similarity judgement of emotional concepts and manipulated the contextual congruency of the responses along the two main affective dimensions of hedonic valence and physiological activation, respectively. Behavioural and kinematics (mouse-tracking) measures were combined to gather a novel 'similarity index' between emotional concepts, to derive topographical maps of their mental representations. Self-report (interoceptive sensibility, positive-negative affectivity, depression) and physiological measures (heart rate variability, HRV) have been collected to explore their possible association with emotional conceptual representation. Results indicate that emotional concepts typically associated with low arousal profit by contextual congruency, with faster responses and reduced uncertainty when contextual ambiguity decreases. The emotional maps recreate two almost orthogonal axes of valence and arousal, and the similarity measure captures the smooth boundaries between emotions. The emotional map of a subgroup of individuals with low positive affectivity reveals a narrower conceptual distribution, with variations in positive emotions and in individuals with reduced arousal (such as those with reduced HRV). Our work introduces a novel methodology to study emotional conceptual representations, bringing the behavioural dynamics of decision-making processes and choice uncertainty into the affective domain. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.