Interoception

Biofeedback-based training for stress management in daily hassles: an intervention study

BACKGROUND

The day-to-day causes of stress are called daily hassles. Daily hassles are correlated with ill health. Biofeedback (BF) is one of the tools used for acquiring stress-coping skills. However, the anatomical correlates of the effects of BF with long training periods remain unclear. In this study, we aimed to investigate this.

METHODS

PARTICIPANTS WERE ASSIGNED RANDOMLY TO TWO GROUPS: the intervention group and the control group. Participants in the intervention group performed a biofeedback training (BFT) task (a combination task for heart rate and cerebral blood flow control) every day, for about 5 min once a day. The study outcomes included MRI, psychological tests (e.g., Positive and Negative Affect Schedule, Center for Epidemiologic Studies Depression Scale, and Brief Job Stress Questionnaire), and a stress marker (salivary cortisol levels) before (day 0) and after (day 28) the intervention.

RESULTS

We observed significant improvements in the psychological test scores and salivary cortisol levels in the intervention group compared to the control group. Furthermore, voxel-based morphometric analysis revealed that compared to the control group, the intervention group had significantly increased regional gray matter (GM) volume in the right lateral orbitofrontal cortex, which is an anatomical cluster that includes mainly the left hippocampus, and the left subgenual anterior cingulate cortex. The GM regions are associated with the stress response, and, in general, these regions seem to be the most sensitive to the detrimental effects of stress.

CONCLUSIONS

Our findings suggest that our BFT is effective against the GM structures vulnerable to stress.

The impact of cardiac perception on emotion experience and cognitive performance under mental stress

Mental stress evokes several physiological responses such as the acceleration of heart rate, increase of electrodermal activity and the release of adrenaline. Moreover, physiological stress responses interact with emotional and behavioral stress responses. In the present study we provide evidence that viscero-sensory feedback from the heart (cardiac perception) is an important factor modulating emotional and cognitive stress responses. In our study, we compared participants with high versus low cardiac perception using a computerized mental stress task, in which they had to respond to rapidly presented visual and acoustic stimuli. Additionally, we assessed physiological responses (heart rate, skin conductance). Participants high in cardiac perception reported more negative emotions and showed worse task performance under the stressor than participants low in cardiac perception. These results were not moderated by physiological responses. We conclude that cardiac perception modulates stress responses by intensifying negative emotions and by impairing cognitive performance.

Cardiac Perception Enhances Stress Experience

In the present study we aimed to investigate the impact of the ability to perceive bodily changes as indexed by the perception of one’s heartbeat (cardiac perception) on emotional experience when being confronted with a mental stressor. To induce stress, participants high and low in cardiac perception performed a computerized mental arithmetic test while listening to a white noise increasing in volume. Emotional experience and heart rate were assessed as indices of stress response. Our results show that participants high in cardiac perception reported more negative emotions during the stress period compared to participants low in cardiac perception, though heart rate did not differ between the groups. Our findings suggest that cardiac perception moderates the stress experience by enhancing the perceived emotion. Thus we were able to demonstrate that cardiac perception contributes as a factor explaining the variance in individuals’ emotional response to a stressor.

Treatment approaches for interoceptive dysfunctions in drug addiction

There is emerging evidence that individuals with drug addiction have dysfunctions in brain systems that are important for interoceptive processing, which include, among others, the insular and the anterior cingulate cortices. These individuals may not be expending sufficient neural resources to process perturbations of the interoceptive state but may exert over-activation of these systems when processing drug-related stimuli. As a consequence, insufficient detection and processing of interoceptive state changes may result in inadequate anticipation and preparation to adapt to environmental challenges, e.g., adapt to abstinence in the presence of withdrawal symptoms. Here, we integrate interoceptive dysfunction in drug-addicted individuals, with the neural basis for meditation and exercise to develop a heuristic to target the interoceptive system as potential treatments for drug addiction. First, it is suggested that mindfulness-based approaches can modulate both interoceptive function and insular activation patterns. Second, there is an emerging literature showing that the regulation of physical exercise in the brain involves the insula and anterior cingulate cortex and that intense physical exercise is associated with a insula changes that may provide a window to attenuate the increased interoceptive response to drug-related stimuli. It is concluded that the conceptual framework of interoceptive dysfunctions in drug addiction and the experimental findings in meditation and exercise provide a useful approach to develop new interventions for drug addiction.

Brief communication: investigating the relationship between psychopathy and interoceptive awareness

Psychopathy is a disorder that is characterized by marked emotional deficiencies. Because previous studies suggest that an individual's sensitivity to bodily signals--or "interoceptive awareness"--is associated with various components of emotional functioning, the authors expected this capacity to be reduced in psychopathic individuals. Therefore, the current study examined the relationship between psychopathy and interoceptive awareness by assessing heartbeat detection abilities in a group of 75 male personality disordered offenders, varying in their degree of psychopathy, as assessed with the Hare Psychopathy Checklist-Revised (PCL-R; Hare, 2003). Regression analyses revealed that PCL-R Facet 4, which reflects antisocial behavior, was predictive of reduced interoceptive awareness. These findings suggest that the expression of psychopathic behavior might be influenced by an attenuated sensitivity to one's own bodily signals.

Interoception and drug addiction

The role of interoception and its neural basis with relevance to drug addiction is reviewed. Interoception consists of the receiving, processing, and integrating body-relevant signals with external stimuli to affect ongoing motivated behavior. The insular cortex is the central nervous system hub to process and integrate these signals. Interoception is an important component of several addiction relevant constructs including arousal, attention, stress, reward, and conditioning. Imaging studies with drug-addicted individuals show that the insular cortex is hypo-active during cognitive control processes but hyperactive during cue reactivity and drug-specific, reward-related processes. It is proposed that interoception contributes to drug addiction by incorporating an "embodied" experience of drug uses together with the individual's predicted versus actual internal state to modulate approach or avoidance behavior, i.e. whether to take or not to take drugs. This opens the possibility of two types of interventions. First, one may be able to modulate the embodied experience by enhancing insula reactivity where necessary, e.g. when engaging in drug seeking behavior, or attenuating insula when exposed to drug-relevant cues. Second, one may be able to reduce the urge to act by increasing the frontal control network, i.e. inhibiting the urge to use by employing cognitive training. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Enhanced cardiac perception is associated with increased susceptibility to framing effects

Previous studies suggest in line with dual process models that interoceptive skills affect controlled decisions via automatic or implicit processing. The "framing effect" is considered to capture implicit effects of task-irrelevant emotional stimuli on decision-making. We hypothesized that cardiac awareness, as a measure of interoceptive skills, is positively associated with susceptibility to the framing effect. Forty volunteers performed a risky-choice framing task in which the effect of loss versus gain frames on decisions based on identical information was assessed. The results show a positive association between cardiac awareness and the framing effect, accounting for 24% of the variance in the framing effect. These findings demonstrate that good interoceptive skills are linked to poorer performance in risky choices based on ambivalent information when implicit bias is induced by task-irrelevant emotional information. These findings support a dual process perspective on decision-making and suggest that interoceptive skills mediate effects of implicit bias on decisions.

What the heart forgets: Cardiac timing influences memory for words and is modulated by metacognition and interoceptive sensitivity

Mental functions are influenced by states of physiological arousal. Afferent neural activity from arterial baroreceptors at systole conveys the strength and timing of individual heartbeats to the brain. We presented words under limited attentional resources time-locked to different phases of the cardiac cycle, to test a hypothesis that natural baroreceptor stimulation influences detection and subsequent memory of words. We show memory for words presented around systole was decreased relative to words at diastole. The deleterious memory effect of systole was greater for words detected with low confidence and amplified in individuals with low interoceptive sensitivity, as indexed using a heartbeat counting task. Our observations highlight an important cardiovascular channel through which autonomic arousal impacts a cognitive function, an effect mitigated by metacognition (perceptual confidence) and interoceptive sensitivity.

Body conscious? Interoceptive awareness, measured by heartbeat perception, is negatively correlated with self-objectification

BACKGROUND

'Self-objectification' is the tendency to experience one's body principally as an object, to be evaluated for its appearance rather than for its effectiveness. Within objectification theory, it has been proposed that self-objectification accounts for the poorer interoceptive awareness observed in women, as measured by heartbeat perception. Our study is, we believe, the first specifically to test this relationship.

METHODOLOGY/PRINCIPAL FINDINGS

Using a well-validated and reliable heartbeat perception task, we measured interoceptive awareness in women and compared this with their scores on the Self-Objectification Questionnaire, the Self-Consciousness Scale and the Body Consciousness Questionnaire. Interoceptive awareness was negatively correlated with self-objectification. Interoceptive awareness, public body consciousness and private body consciousness together explained 31% of the variance in self-objectification. However, private body consciousness was not significantly correlated with interoceptive awareness, which may explain the many nonsignificant results in self-objectification studies that have used private body consciousness as a measure of body awareness.

CONCLUSIONS/SIGNIFICANCE

We propose interoceptive awareness, assessed by heartbeat perception, as a measure of body awareness in self-objectification studies. Our findings have implications for those clinical conditions, in women, which are characterised by self-objectification and low interoceptive awareness, such as eating disorders.

Interoceptive Awareness as a Moderator of Affective Responses to Social Exclusion

Previous research has yielded inconsistent results concerning affective reactions to social exclusion. The present study provides evidence that conscious perception of bodily signals (“interoceptive awareness”) constitutes an important moderating factor in this context. We compared participants with high versus low cardiac interoceptive awareness in regard to affective, cognitive, and physiological measures while they were included and excluded in a discussion with confederates. Participants with high interoceptive awareness showed a smaller decrease of positive affect and perceived acceptance as well as a smaller increase of negative affect and perceived rejection when comparing an inclusion phase with a subsequent exclusion phase than did participants with low interoceptive awareness. No significant differences in cognitive and physiological measures were observed. We assume that individuals with high interoceptive awareness, to whom physiological signals are more easily accessible, reduce aversive states to a larger degree by using somatic information for self-regulation.

The Multidimensional Assessment of Interoceptive Awareness (MAIA)

This paper describes the development of a multidimensional self-report measure of interoceptive body awareness. The systematic mixed-methods process involved reviewing the current literature, specifying a multidimensional conceptual framework, evaluating prior instruments, developing items, and analyzing focus group responses to scale items by instructors and patients of body awareness-enhancing therapies. Following refinement by cognitive testing, items were field-tested in students and instructors of mind-body approaches. Final item selection was achieved by submitting the field test data to an iterative process using multiple validation methods, including exploratory cluster and confirmatory factor analyses, comparison between known groups, and correlations with established measures of related constructs. The resulting 32-item multidimensional instrument assesses eight concepts. The psychometric properties of these final scales suggest that the Multidimensional Assessment of Interoceptive Awareness (MAIA) may serve as a starting point for research and further collaborative refinement.

Interoception across modalities: on the relationship between cardiac awareness and the sensitivity for gastric functions

The individual sensitivity for ones internal bodily signals ("interoceptive awareness") has been shown to be of relevance for a broad range of cognitive and affective functions. Interoceptive awareness has been primarily assessed via measuring the sensitivity for ones cardiac signals ("cardiac awareness") which can be non-invasively measured by heartbeat perception tasks. It is an open question whether cardiac awareness is related to the sensitivity for other bodily, visceral functions. This study investigated the relationship between cardiac awareness and the sensitivity for gastric functions in healthy female persons by using non-invasive methods. Heartbeat perception as a measure for cardiac awareness was assessed by a heartbeat tracking task and gastric sensitivity was assessed by a water load test. Gastric myoelectrical activity was measured by electrogastrography (EGG) and subjective feelings of fullness, valence, arousal and nausea were assessed. The results show that cardiac awareness was inversely correlated with ingested water volume and with normogastric activity after water load. However, persons with good and poor cardiac awareness did not differ in their subjective ratings of fullness, nausea and affective feelings after drinking. This suggests that good heartbeat perceivers ingested less water because they subjectively felt more intense signals of fullness during this lower amount of water intake compared to poor heartbeat perceivers who ingested more water until feeling the same signs of fullness. These findings demonstrate that cardiac awareness is related to greater sensitivity for gastric functions, suggesting that there is a general sensitivity for interoceptive processes across the gastric and cardiac modality.

Coherence between emotional experience and physiology: does body awareness training have an impact?

Two fundamental issues in emotion theory and research concern: (a) the role of emotion in promoting response coherence across different emotion systems; and (b) the role of awareness of bodily sensations in the experience of emotion. The present study poses a question bridging the two domains; namely, whether training in Vipassana meditation or dance, both of which promote attention to certain kinds of bodily sensations, is associated with greater coherence between the subjective and physiological aspects of emotion. We used lag correlations to examine second-by-second coherence between subjective emotional experience and heart period within individuals across four different films. Participants were either: (a) experienced Vipassana meditators (attention to visceral sensations), (b) experienced dancers (attention to somatic sensations), and (c) controls with no meditation or dance experience. Results indicated a linear relationship in coherence, with meditators having highest levels, dancers having intermediary levels, and controls having lowest levels. We conclude that the coherence between subjective and cardiac aspects of emotion is greater in those who have specialized training that promotes greater body awareness.

Interoception in anxiety and depression

We review the literature on interoception as it relates to depression and anxiety, with a focus on belief, and alliesthesia. The connection between increased but noisy afferent interoceptive input, self-referential and belief-based states, and top-down modulation of poorly predictive signals is integrated into a neuroanatomical and processing model for depression and anxiety. The advantage of this conceptualization is the ability to specifically examine the interface between basic interoception, self-referential belief-based states, and enhanced top-down modulation to attenuate poor predictability. We conclude that depression and anxiety are not simply interoceptive disorders but are altered interoceptive states as a consequence of noisily amplified self-referential interoceptive predictive belief states.

Differential brain activation to angry faces by elite warfighters: neural processing evidence for enhanced threat detection

BACKGROUND

Little is known about the neural basis of elite performers and their optimal performance in extreme environments. The purpose of this study was to examine brain processing differences between elite warfighters and comparison subjects in brain structures that are important for emotion processing and interoception.

METHODOLOGY/PRINCIPAL FINDINGS

Navy Sea, Air, and Land Forces (SEALs) while off duty (n = 11) were compared with n = 23 healthy male volunteers while performing a simple emotion face-processing task during functional magnetic resonance imaging. Irrespective of the target emotion, elite warfighters relative to comparison subjects showed relatively greater right-sided insula, but attenuated left-sided insula, activation. Navy SEALs showed selectively greater activation to angry target faces relative to fearful or happy target faces bilaterally in the insula. This was not accounted for by contrasting positive versus negative emotions. Finally, these individuals also showed slower response latencies to fearful and happy target faces than did comparison subjects.

CONCLUSIONS/SIGNIFICANCE

These findings support the hypothesis that elite warfighters deploy greater processing resources toward potential threat-related facial expressions and reduced processing resources to non-threat-related facial expressions. Moreover, rather than expending more effort in general, elite warfighters show more focused neural and performance tuning. In other words, greater neural processing resources are directed toward threat stimuli and processing resources are conserved when facing a nonthreat stimulus situation.

Interoceptive sensitivity in anxiety and anxiety disorders: an overview and integration of neurobiological findings

Interoceptive sensitivity, particularly regarding heartbeat, has been suggested to play a pivotal role in the pathogenesis of anxiety and anxiety disorders. This review provides an overview of methods which are frequently used to assess heartbeat perception in clinical studies and summarizes presently available results referring to interoceptive sensitivity with respect to heartbeat in anxiety-related traits (anxiety sensitivity, state/trait anxiety), panic disorder and other anxiety disorders. In addition, recent neurobiological studies of neuronal activation correlates of heartbeat perception using positron emission tomography (PET), functional magnetic resonance imaging (fMRI) or electroencephalographic (EEG) techniques are presented. Finally, possible clinical and therapeutic implications (e.g., beta-blockers, biofeedback therapy, cognitive interventions and interoceptive exposure) of the effects of heartbeat perception on anxiety and the anxiety disorders and the potential use of interoceptive sensitivity as an intermediate phenotype of anxiety disorders in future neurobiological and genetic studies are discussed.

The neurocircuitry of impaired insight in drug addiction

More than 80% of addicted individuals fail to seek treatment, which might reflect impairments in recognition of severity of disorder. Considered by some as intentional deception, such 'denial' might instead reflect dysfunction of brain networks subserving insight and self-awareness. Here we review the scant literature on insight in addiction and integrate this perspective with the role of: (i) the insula in interoception, self-awareness and drug craving; (ii) the anterior cingulate in behavioral monitoring and response selection (relevant to disadvantageous choices in addiction); (iii) the dorsal striatum in automatic habit formation; and (iv) drug-related stimuli that predict emotional behavior in addicted individuals, even without conscious awareness. We discuss implications for clinical treatment including the design of interventions to improve insight into illness severity in addiction.

Interoceptive awareness declines with age

Aging has been shown to increase sensory thresholds for a variety of exteroceptive and proprioceptive stimuli. However, the influence of aging on interoceptive awareness has received relatively little empirical attention. Here we report an inverse association between aging and interoception, as indexed by the ability to sense the heartbeat at rest. In a group of 59 participants ranging in age from 22 to 63 years, age inversely predicted heartbeat detection ability, both within and across several measurement sessions. On average, age accounted for 30% of the variance in heartbeat detection accuracy. Other attribute variables including body mass index and sex were not related to heartbeat detection ability. These findings provide clear empirical evidence that interoception, much like exteroception and proprioception, declines with age.

Body awareness: construct and self-report measures

Objectives

Heightened body awareness can be adaptive and maladaptive. Improving body awareness has been suggested as an approach for treating patients with conditions such as chronic pain, obesity and post-traumatic stress disorder. We assessed the psychometric quality of selected self-report measures and examined their items for underlying definitions of the construct.

Data sources

PubMed, PsychINFO, HaPI, Embase, Digital Dissertations Database.

Review methods

Abstracts were screened; potentially relevant instruments were obtained and systematically reviewed. Instruments were excluded if they exclusively measured anxiety, covered emotions without related physical sensations, used observer ratings only, or were unobtainable. We restricted our study to the proprioceptive and interoceptive channels of body awareness. The psychometric properties of each scale were rated using a structured evaluation according to the method of McDowell. Following a working definition of the multi-dimensional construct, an inter-disciplinary team systematically examined the items of existing body awareness instruments, identified the dimensions queried and used an iterative qualitative process to refine the dimensions of the construct.

Results

From 1,825 abstracts, 39 instruments were screened. 12 were included for psychometric evaluation. Only two were rated as high standard for reliability, four for validity. Four domains of body awareness with 11 sub-domains emerged. Neither a single nor a compilation of several instruments covered all dimensions. Key domains that might potentially differentiate adaptive and maladaptive aspects of body awareness were missing in the reviewed instruments.

Conclusion

Existing self-report instruments do not address important domains of the construct of body awareness, are unable to discern between adaptive and maladaptive aspects of body awareness, or exhibit other psychometric limitations. Restricting the construct to its proprio- and interoceptive channels, we explore the current understanding of the multi-dimensional construct and suggest next steps for further research.

The Relationship Between Pain Perception and Interoception

The question of whether the perception of externally applied pain stimuli and the perception of interoceptive stimuli are based upon similar neuronal or behavioral processes is still open to debate. If such a similarity exists, one would expect that persons who are highly sensitive to visceral stimuli would also exhibit a higher sensitivity to pain stimuli. The present study investigated the sensitivity to heat pain of individuals with high vs. low cardiac interoceptive sensitivity. Pain threshold and pain tolerance were assessed using a testing-the-limits procedure. Furthermore, participants rated the subjective intensity and unpleasantness of tonic heat stimuli on visual analog scales and in a questionnaire. The results show that pain experience did not differ between participants with high and low interoceptive sensitivity, nor did correlation analyses reveal significant relationships between pain experience and cardiac interoceptive sensitivity. These findings suggest that the pathway of peripheral pain processing is at least partially independent of the pathway of interoceptive sensations.

Alimentary Epigenetics: A Developmental Psychobiological Systems View of the Perception of Hunger, Thirst and Satiety

Hunger, thirst and satiety have an enormous influence on cognition, behavior and development, yet we often take for granted that they are simply inborn or innate. Converging data and theory from both comparative and human domains, however, supports the conclusion that the phenomena hunger, thirst and satiety are not innate but rather emerge probabilistically as a function of experience during individual development. The metatheoretical perspective provided by developmental psychobiological systems theory provides a useful framework for organizing and synthesizing findings related to the development of the perception of hunger, thirst and satiety, or alimentary interoception. It is argued that neither developmental psychology nor the psychology of eating and drinking have adequately dealt with the ontogeny of alimentary interoception and that a more serious consideration of the species-typical developmental system of food and fluid intake and the many modifications that have been made therein is likely necessary for a full understanding of both alimentary and emotional development.

Pathological baroreceptor sensitivity in patients suffering from somatization disorders: do they correlate with symptoms?

AIM

We conducted a study to investigate whether patients with somatization disorders (ICD-10, F45.0) show abnormal values in autonomic testing.

METHOD

35 patients with a diagnosis of somatization disorder (SP) were matched to 35 healthy volunteers (HV). International standardized autonomic testing based on heart rate variation and continuously measured blood pressure signals was used to assess autonomic activity and establish baroreceptor sensitivity (BRS). Three different statistical procedures were used to confirm the reliability of the findings.

RESULTS

There were no statistical differences between the 2 groups in age, BMI, systolic and diastolic blood pressures, and spectral values (total power, low, and high frequency power). However, heart rate was higher (p=0.044) and baroreceptor sensitivity was lower (p=0.002) in the patients compared to the healthy volunteers. Median BRS (+/-S.E.M.) of patients was 9.09+/-0.65 compared to 12.04+/-0.94 ms/mmHg in healthy volunteers. Twenty-two of the 35 patients had a BRS of -1.0S.D. below the mean of HV. SP with lower values differed from SP with normal BRS in values of total power, low-, mid-, and high-frequency bands (p<0.01 to <0.0001). No differences in psychometric testing were found between patients with lower or higher BRS. In addition, no correlation whatsoever was found in relation to autonomic variables between HV and SP, except for a higher LF/HF quotient in the latter (p<0.05).

CONCLUSION

Autonomic regulation was impaired in 62% of patients with a somatization disorder. Severity of clinical symptoms measured by psychometric instruments did not preclude autonomic function impairment. Accordingly, autonomic dysfunction may constitute an independent somatic factor in this patient group.

Interozeptive Sensitivität, Gefühle und Verhaltensregulation

Die zentralnervöse Verarbeitung afferenter Signale aus dem Körperinneren ist nicht nur bei der basalen Kontrolle homöostatischer Prozesse im Körper zur Regulation fundamentaler Adaptationsprozesse des Organismus relevant, sondern spielt zusammen mit der bewussten Perzeptionsgenauigkeit dieser körperlichen Signale („interozeptive Sensitivität“) auch bei der Regulation komplexer kognitiver, emotionaler und behavioraler Prozesse eine nicht zu unterschätzende Rolle. Diese Übersichtsarbeit stellt theoretische Grundlagen zur interozeptiven Sensitivität dar und gibt einen Überblick über aktuelle empirische Forschungsergebnisse.

Interoceptive sensitivity and emotion processing: An EEG study

Theories of emotion consider the self-perception of visceral activity to play an important role in emotion. This study examined the relationship between interoceptive sensitivity and both the subjective emotional experience and the processing of emotional pictures. According to their results in a heartbeat detection task subjects were classified as good (N = 17) or poor (N = 20) heartbeat perceivers. Event-related potentials were recorded while subjects viewed pleasant, neutral and unpleasant pictures and SAM ratings were examined. Good heartbeat perceivers showed significantly greater P300 and slow wave amplitudes for emotional pictures at antero-inferior, medial and posterior electrode sites and experienced a greater arousal for emotional pictures compared to poor heartbeat perceivers. The heartbeat perception score correlated significantly positive both with emotional P300 and slow wave amplitudes as well as with the arousal ratings for emotional pictures. The results indicate that there is a significant and strong association between interoceptive sensitivity and the intensity of emotional experience as well as the central processing of emotional stimuli.

Preattentive processing of heart cues and the perception of heart symptoms in congenital heart disease

The present study was aimed at clarifying whether preattentive processing of heart cues results in biased perception of heart sensations in patients with congenital heart disease (ConHD) who are also highly trait anxious. Twenty-six patients with ConHD and 22 healthy participants categorized heart-related (heart rate) or neutral sensations (constant vibration) as either heart or neutral. Both sensations were evoked using a bass speaker that was attached on the chest of the participant. Before each physical sensation, a subliminal heart-related or neutral prime was presented. Biased perception of heart-sensations would become evident by a delayed categorization of the heart-related sensations. In line with the prediction, a combination of high trait anxiety and ConHD resulted in slower responses after a heart-related sensation that was preceded by a subliminal heart cue. Preattentive processing of harmless heart cues may easily elicit overperception of heart symptoms in highly trait anxious patients with ConHD.

Interoceptive sensitivity and physical effort: Implications for the self-control of physical load in everyday life

This study examined the relationship between interoceptive sensitivity and the behavioral self-regulation of physical load. According to their performance in a heartbeat detection task, 34 participants were classified as good or poor heartbeat perceivers. Participants pedaled on a bicycle ergometer for 15 min and were free to choose the tempo of their cycling. Good heartbeat perceivers covered a significantly shorter distance and showed a significantly smaller increase in mean heart rate, stroke volume, and cardiac output. There were significant negative correlations between heartbeat perception score and covered distance, changes in heart rate, changes in stroke volume, and changes in cardiac output. These results were not explained by differences in physical fitness level (PWC150). The findings suggest that good heartbeat perceivers show a more finely tuned behavioral self-regulation of physical load than poor heartbeat perceivers.

Self-rated health showed a graded association with frequently used biomarkers in a large population sample

BACKGROUND AND OBJECTIVES

Self-rated health is a widely used measure of health status, but its biologic foundations are poorly understood. We investigated the association of frequently used biomarkers with self-rated health, and the role of these biomarkers in the association of self-rated health with mortality.

METHODS

The relation of self-rated health to blood levels of albumin, white blood cell count, hemoglobin, HDL cholesterol, and creatinine was examined in a population-based sample of 4,065 men and women aged 71 years or older. A Cox proportional hazards model was used to determine the association of self-rated health with mortality during 4.9 years. Sociodemographic factors, diagnosed chronic conditions, and activities of daily living disability were controlled for in these analyses.

RESULTS

All the biomarkers showed a graded relationship with self-rated health. After adjusting for other indicators, hemoglobin and white cell count were significantly associated with fair or poor self-rated health. When biomarkers and other indicators were adjusted for, self-rated health still was a significant predictor of mortality.

CONCLUSION

Self-rated health has a biologic basis, and it can be a sensitive barometer of physiologic states. Self-rated health is likely to predict mortality because it covers the spectrum of health conditions better than the variables measured in the study.

Brain structures involved in interoceptive awareness and cardioafferent signal processing: a dipole source localization study

Afferent signals from the body play an important role for emotional and motivational aspects of behavior. Nevertheless, little is known about the cortical and subcortical structures involved in interoceptive processes. Recently, a functional MRI study demonstrated that insula, somatomotor, and cingulated cortices are activated when subjects focus attention on their heartbeats. Aside from the use of imaging data, cardiac awareness has frequently been studied by using the heartbeat-evoked potential (HEP), a brain wave that appears contingent on the heartbeat. The present study aimed at localizing sources of the HEP. Multichannel EEG was recorded in 44 subjects while they performed a heartbeat perception task. This task was used to quantify interoceptive awareness and to subdivide the subjects into good and poor heartbeat perceivers. Analyses showed highest HEP amplitudes over frontal and frontocentral electrode locations in the time range of later than 200 ms after R-wave onset. By means of a BESA dipole-source-analysis, four sources of the HEP were identified which were located in the anterior cingulate, the right insula, the prefrontal cortex, and the left secondary somatosensory cortex. Good heartbeat perceivers showed both significantly higher HEP amplitudes and higher dipole strength than poor heartbeat perceivers in all four cortical sources. We conclude that the identified structures are involved in the processing of cardiac signals, whereby anterior cingulate and right insula seem to serve as interoceptive centers for cardioception.

Double dissociation of exteroceptive and interoceptive feedback systems in the orbital and ventromedial prefrontal cortex of humans

The primate ventral prefrontal cortex contains two densely interconnected subregions: a lateral/orbital cortex processing primarily sensory/exteroceptive information, and a ventromedial cortex processing primarily visceroappetitive/interoceptive information. These regions have major afferents from and efferents to other associative cortices. The organization of these structures leads to an hypothesized role in feedback processing. We use neuroimaging to test this model, defined so far mostly through anatomical studies. Healthy volunteers were trained operantly on a transitive inference task (A>B, B>C ==> A>C) requiring flexible manipulation of feedback to solve. Two groups of subjects learned an arbitrary face hierarchy, one adjacent face pair at a time; each group received either visual/exteroceptive ("XXXX") or visceroappetitive/interoceptive (fruit juice) feedback for correct responses to adjacent face pairs. After task acquisition, the subjects were tested on novel stimulus pairs (i.e., nonadjacent, TEST) derived from the acquired hierarchy. The TEST condition required transitive inference. No feedback was provided during TEST. Brain activity during TEST in the group trained with visual/exteroceptive feedback increased in the orbital prefrontal cortex and decreased in the ventromedial prefrontal cortex. In contrast, brain activity during TEST in the group trained with visceroappetitive/interoceptive feedback decreased in the orbital prefrontal cortex and increased in the ventromedial prefrontal cortex. These results provide functional evidence, consistent with previous anatomical studies, for two major feedback systems in human ventral prefrontal cortex: a lateral system specialized for exteroceptive information and a medial system specialized for interoceptive information. Although highly interconnected, there is a double dissociation of function between these networks in healthy humans.

Are Current Theories of Panic Falsifiable?

The authors examine 6 theories of panic attacks as to whether empirical approaches are capable of falsifying them and their heuristic value. The authors conclude that the catastrophic cognitions theory is least falsifiable because of the elusive nature of thoughts but that it has greatly stimulated research and therapy. The vicious circle theory is falsifiable only if the frightening internal sensations are specified. The 3-alarms theory postulates an indeterminate classification of attacks. Hyperventilation theory has been falsified. The suffocation false alarm theory lacks biological parameters that unambiguously index dyspnea or its distinction between anticipatory and panic anxiety. Some correspondences postulated between clinical phenomena and brain areas by the neuroanatomical hypothesis may be falsifiable if panic does not depend on specific thoughts. All these theories have heuristic value, and their unfalsifiable aspects are capable of modification.

Heartbeat sensitivity in adults with congenital heart disease

This study tested the hypothesis that patients with a congenital heart disease are sensitive regarding heartbeat perception, reflected in enhanced attention for heartbeat, estimation of own heart rate, and a vulnerability to become anxious by listening to heartbeat sounds. Twenty adults with a congenital heart disease, and 20 healthy controls conducted 3 experimental tasks: a concentration task during distraction by heartbeat sounds, own heart rate estimation, and exposure to different patterns of heartbeat sounds. The results showed that patients were more distracted by heartbeat, and were also worse at estimating heart rate than controls. However, heartbeat sounds did not evoke anxiety. In conclusion, patients with a congenital heart disease may differ from controls in heartbeat perception, but there was no support for obsessive monitoring for heartbeat or excessive reactions to heartbeat sounds.

Interoceptive sensitivity and self-reports of emotional experience

People differ in the extent to which they emphasize feelings of activation or deactivation in their verbal reports of experienced emotion, termed arousal focus (AF). Two multimethod studies indicate that AF is linked to heightened interoceptive sensitivity (as measured by performance on a heartbeat detection task). People who were more sensitive to their heartbeats emphasized feelings of activation and deactivation when reporting their experiences of emotion over time more than did those who were less sensitive. This relationship was not accounted for by several other variables, including simple language effects. Implications for the role of interoception in experienced emotion and the validity of self-reported emotion are discussed.

Negative thoughts in adults with congenital heart disease

BACKGROUND

Many patients with congenital heart disease have persistent cardiac defects, psychosocial adjustment problems, and a poor quality of life. This study tested the relationship between negative thoughts and adaptation to congenital heart disease.

METHODS

Eighty-two adult out-Patients with congenital heart disease were divided on the basis of few, moderate or many negative thoughts. Group differences were tested in medical and psychosocial adjustment variables (including negative emotions), and quality of life.

RESULTS

Patients with many negative thoughts scored worse on psychosocial adjustment and quality of life, irrespective of severity of cardiac deviation, according to the cardiologist, New York Heart Association classification, number of passed and expected surgery, or use of medication.

CONCLUSION

Negative affect in general, rather than negative thoughts is decisive in psychosocial adjustment and quality of life. Psychological intervention would be helpful for many patients.

Can humans perceive their brain states?

Although the brain enables us to perceive the external world and our body, it remains unknown whether brain processes themselves can be perceived. Brain tissue does not have receptors for its own activity. However, the ability of humans to acquire self-control of brain processes indicates that the perception of these processes may also be achieved by learning. In this study patients learned to control low-frequency components of their EEG: the so-called slow cortical potentials (SCPs). In particular "probe" sessions, the patients estimated the quality of the SCP shift they had produced in the preceding trial. The correspondence between the recorded SCP amplitudes and the subjective estimates increased with training. The ability to perceive the SCPs was related to the ability to control them; this perception was not mediated by peripheral variables such as changes in muscle tonus and cannot be reduced to simple vigilance monitoring. These data provide evidence that humans can learn to perceive the neural activity of their brain. Alternative interpretations are discussed.

Proprioception in somatoform disorders

20 patients with somatoform disorders as defined by DSM-IV and 20 healthy controls were examined for their proprioception. Several psychophysiological theories of somatoform disorders suggest biased proprioceptive abilities. The primary question is, whether we may find an inaccurate myogen perception in somatization as suggested by the approach of Bischoff or a more precise proprioception as may be derived from concepts of a higher awareness of body reactions. Furthermore it is expected, that somatoform patients perceive their muscle tension more intensely than do healthy subjects. Proprioceptive abilities were tested using a visual EMG biofeedback task. Resulting objective data and subjective ratings were analyzed within a psychophysiological regression approach which allows one to estimate the reliability, precision and intensity of proprioception. Results revealed that somatoform subjects demonstrated a more precise but not a more intense perception of muscle tension than did healthy controls.

Interoception: the inside story--a model for psychosomatic processes

OBJECTIVE

To comprehend psychosomatic processes, it will be necessary to understand the brain's influences on bodily functions and also the body's afferent sensory input to the central nervous system, including the effects of this input on behavior and cognitive functions, especially emotion. The objective of this Presidential Address is to review what is known circa the year 2000 of the processes and mechanisms of visceral sensory psychobiology, often called interoception.

METHODS

Over 1000 publications that have appeared since the 19th century were reviewed to prepare this review, including a group that are specifically cited here.

RESULTS

Factors and data were reviewed that were identified as germane to understanding interoception. These included definitional issues, historical roots, the neural basis, studies and results in the cardiovascular-respiratory and alimentary-gastrointestinal systems, studies of emotion, and studies in people with mental disorders. Drug and hormone effects, pain, proprioception, and phantom limb or organ factors, and the role of awareness were briefly described. Methodological issues, methods of study including functional imaging, and possible future directions for study were identified.

CONCLUSIONS

Understanding the physical basis of psychosomatic processes, including the so-called mind-body problem, will require a detailed understanding the psychobiology of interoception.

Effects of yohimbine on cerebral blood flow, symptoms, and physiological functions in humans

OBJECTIVE

Increases in adrenergic activity are associated with stress, anxiety, and other psychiatric, neurological, and medical disorders. To improve understanding of normal CNS adrenergic function, CBF responses to adrenergic stimulation were determined.

METHODS

Using PET, the CBF changes after intravenous yohimbine, an alpha2-adrenoreceptor antagonist that produces adrenergic activation, were compared with placebo in nine healthy humans. Heart rate, blood pressure, Paco2, plasma catecholamines, and symptom responses were also determined.

RESULTS

Among nonscan variables, yohimbine produced significant symptom increases (including a panic attack in one subject), a decrease in Paco2 due to hyperventilation, increases in systolic and diastolic blood pressure, and a trend toward a significant norepinephrine increase. Among scan results, yohimbine produced a significant decrease in whole-brain absolute CBF; regional decreases were greatest in cortical areas. Medial frontal cortex, thalamus, insular cortex, and cerebellum showed significant increases after normalization to whole brain. Medial frontal CBF change was correlated with increases in anxiety. A panic attack produced an increase instead of a decrease in whole-brain CBF. Factors potentially contributing to the observed CBF changes were critically reviewed. Specific regional increases were most likely due in large part to activation produced by adrenergically induced anxiety and visceral symptoms.

CONCLUSIONS

This study supports the relationship of anxiety and interoceptive processes with medial frontal, insular, and thalamic activation and provides a baseline for comparison of normal yohimbine-induced CNS adrenergic activation, adrenergically-based symptoms, and other markers of adrenergic function to stress, emotion, and the adrenergic pathophysiologies of various CNS-related disorders.

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Oncologists have been reluctant a long time to accept the existence of spontaneous remissions in cancer disease. The considerable number of patients whose cancer-disease has regressed without (adequate) treatment should have allayed these doubts. Such remissions could serve as a kind of natural experiments that may lead to greater insights in the biology of tumours and to more efficient therapeutic strategies. In the moment the discussion deals with the explanation of spontaneous remissions by the existing biological or psychosomatic theories. Whereas the fact of spontaneous remissions was denied on the one hand some people claim the occurrence of such remissions for themselves without justification. In order to obtain an epidemiological register of these cases it would be necessary to document all patients in question in a standardised manner. Such a set of data should include psychosocial variable as well since the psychosomatic approach seems to be even more in danger of speculations that resemble closely the causal attributions of the patients.