Interoception and Positive Symptoms in Schizophrenia

Interoception in anxiety, depression, and psychosis: a review

Research has examined the relationship between interoception and anxiety, depression, and psychosis; however, it is unclear which aspects of interoception have been systematically examined, what the combined findings are, and which areas require further research. To answer these questions, we systematically searched and narratively synthesised relevant reviews, meta-analyses, and theory papers (total n = 34). Existing systematic reviews and meta-analyses (anxiety n = 2; depression n = 2; psychosis n = 0), focus on cardiac interoceptive accuracy (heartbeat perception), and indicate that heartbeat perception is not systematically impaired in anxiety or depression. Heartbeat perception might be poorer in people with psychosis, but further evidence is needed. Other aspects of interoception, such as different body systems and processing levels, have been studied but not systematically reviewed. We highlight studies examining these alternative bodily domains and levels, review the efficacy of interoception-based psychological interventions, and make suggestions for future research.

Funding

Wellcome Trust UK.

Aberrant heartbeat-evoked potential in schizophrenia

Self-disturbance is considered a core feature underlying the psychopathology of schizophrenia. Interoception has an important role in the development of a sense of self, leading to increased interest in the potential contribution of abnormal interoception to self-disturbances in schizophrenia. Several neuropsychological studies have demonstrated aberrant interoception in schizophrenia. However, cortical interoceptive processing has not yet been thoroughly investigated. Thus, we sought to examine resting-state heartbeat-evoked potential (HEP) in this population. We hypothesized that patients with schizophrenia would exhibit significant alterations in HEP compared to healthy controls (HCs). In this cross-sectional electroencephalogram (EEG) study, we compared the HEPs between age- and sex-matched groups of patients with schizophrenia and HCs. A 10-min resting-state EEG with eyes closed and an electrocardiogram (ECG) were recorded and analyzed for the time window of 450 ms to 500 ms after an ECG R peak. A positive HEP shift was observed in the frontal-central regions (F [1, 82] = 7.402, p = 0.008, partial η2 = 0.009) in patients with schizophrenia (n = 61) when compared with HCs (n = 31) after adjusting for confounders such as age, sex, and heart rate. A cluster-based correction analysis revealed that the HEP around the right frontal area (Fp2, F4, and F8) showed the most significant group differences (F [1, 82] = 10.079, p = 0.002, partial η2 = 0.021), with a peak at the F4 electrode site (F [1, 82] = 12.646, p < 0.001, partial η2 = 0.069). We observed no correlation between HEP and symptoms in patients with schizophrenia. A positive shift of HEP during the late component could reflect a trait abnormality in schizophrenia. Further research is required to determine the association between the altered cortical interoceptive processing indexed with HEP and self-disturbances in schizophrenia.

Systematic review and meta-analysis of the visual mismatch negativity in schizophrenia

Mismatch negativity (MMN) is an event-related potential component automatically elicited by events that violate predictions based on prior events. To elicit this component, researchers use stimulus repetition to induce predictions, and the MMN is obtained by subtracting the brain response to rare or unpredicted stimuli from that of frequent stimuli. Under the Predictive Processing framework, one increasingly popular interpretation of the mismatch response postulates that MMN represents a prediction error. In this context, the reduced MMN amplitude to auditory stimuli has been considered a potential biomarker of Schizophrenia, representing a reduced prediction error and the inability to update the mental model of the world based on the sensory signals. It is unclear, however, whether this amplitude reduction is specific for auditory events or if the visual MMN reveals a similar pattern in schizophrenia spectrum disorder. This review and meta-analysis aimed to summarise the available literature on the vMMN in schizophrenia. A systematic literature search resulted in 10 eligible studies that resulted in a combined effect size of g = -.63, CI [-.86, -.41], reflecting lower vMMN amplitudes in patients. These results are in line with the findings in the auditory domain. This component offers certain advantages, such as less susceptibility to overlap with components generated by attentional demands. Future studies should use vMMN to explore abnormalities in the Predictive Processing framework in different stages and groups of the SSD and increase the knowledge in the search for biomarkers in schizophrenia.

Aberrant Cardiac Interoception in Psychosis

BACKGROUND AND HYPOTHESIS

There is mounting evidence that cardiac interoception, the perception of one's heartbeat, is central to affective experiences. It has been proposed that symptoms of psychosis could arise from interoceptive dysfunction. Here we hypothesized that people with psychotic disorders would have a specific impairment in cardiac interoception, over and above broader perceptual deficits.

STUDY DESIGN

43 adults with a history of psychosis (31 schizophrenia, 12 schizoaffective disorder) and 41 matched control participants completed a heart rate discrimination task. Participants responded to whether they perceived a sequence of auditory tones to be faster or slower than their heart rate. By trialing a range of auditory tone rates, we estimated a threshold for each participant, the difference between perceived heart rate and actual heart rate. To test whether differences were specific to interoception, participants completed an exteroceptive control condition, testing their discrimination of the rate of 2 sets of audible sounds instead of heart rate.

STUDY RESULTS

Participants with a history of psychosis had greater absolute differences between perceived and actual heart rate, indicating over- or under-estimation of heart rate compared to healthy controls. This difference was specific to the interoceptive condition, and not explained by group differences in exteroceptive perception.

CONCLUSIONS

Psychotic disorders are associated with misestimation of heart rate. Further research may elucidate whether interoceptive abnormalities contribute to specific symptoms such as somatic delusions or affective features, and whether interoception could be a treatment target in psychotic disorders.

The cognitive neuroscience of self-awareness: Current framework, clinical implications, and future research directions

Self-awareness, the ability to take oneself as the object of awareness, has been an enigma for our species, with different answers to this question being provided by religion, philosophy, and, more recently, science. The current review aims to discuss the neurocognitive mechanisms underlying self-awareness. The multidimensional nature of self-awareness will be explored, suggesting how it can be thought of as an emergent property observed in different cognitive complexity levels, within a predictive coding approach. A presentation of alterations of self-awareness in neuropsychiatric conditions will ground a discussion on alternative frameworks to understand this phenomenon, in health and psychopathology, with future research directions being indicated to fill current gaps in the literature. This article is categorized under: Philosophy > Consciousness Psychology > Brain Function and Dysfunction Neuroscience > Cognition.

Recognition of others' interoceptive states in those with and without eating disorders

BACKGROUND

The ability to recognize one's own emotions is associated with one's ability to recognize others' emotions. Beyond the domain of emotion, however, the relationship between recognition of one's own internal states (interoception) and others' interoceptive states has not been investigated, either in the typical population or clinical groups with interoceptive difficulties (e.g. eating disorders; EDs).

METHOD

This study investigated recognition of one's own and others' internal states in adults with and without eating disorders, using a high frequency visual noise paradigm. Participants completed self-report measures of interoception, alexithymia (difficulties recognising one's own emotional internal states) and ED symptomatology, and the Heartbeat Counting Task measure of cardiac interoceptive accuracy.

RESULTS

Alexithymia was significantly negatively correlated with recognition of others' interoceptive states. EDs were not associated with difficulties recognising others' interoceptive states.

CONCLUSIONS

The ability to recognise one's own emotional internal states is associated with the recognition of others' interoceptive states, which may contribute to social skills and the ability to care for others.

Impaired emotional awareness is associated with childhood maltreatment exposure and positive symptoms in schizophrenia

Objectives

Evidence suggests that emotional awareness-the ability to identify and label emotions-may be impaired in schizophrenia and related to positive symptom severity. Exposure to childhood maltreatment is a risk factor for both low emotional awareness and positive symptoms.

Methods

The current investigation examines associations between a performance-based measure of emotional awareness, positive symptom severity, and childhood maltreatment exposure in 44 individuals with a schizophrenia-spectrum disorder and 48 healthy comparison participants using the electronic Levels of Emotional Awareness Scale (eLEAS), Positive and Negative Syndrome Scale (PANSS) and Childhood Trauma Questionnaire (CTQ).

Results

Patients demonstrated significant deficits in emotional awareness overall, which was true for both self and others. In patients, lower emotional awareness was significantly associated with more severe positive symptoms. Emotional awareness was significantly impaired in patients with schizophrenia with self-reported maltreatment exposure, relative to other groups. Severity of maltreatment was not significantly associated with emotional awareness or positive symptoms when looking continuously, and there was no significant indirect effect.

Conclusion

These data suggest that emotional awareness impairments observed in schizophrenia may be exacerbated by exposure to childhood maltreatment, possibly putting individuals at greater risk for experiencing positive symptoms of psychosis.

Trait Mindfulness in Psychotic Disorders: Dimensions Predicting Symptoms, Cognition, and Functional Outcome

Mindfulness-based treatments are efficacious for psychotic disorders (PD). However, which components of mindfulness (i.e., attentive monitoring and nonjudgmental acceptance) are most relevant treatment targets is unclear. Further, there is a dearth of literature examining clinical correlates of mindfulness in people with PD. The present study aimed to examine group differences and clinical correlates of mindfulness in people with PD. We hypothesized that PD would report lower monitoring and acceptance than CN and that mindfulness components would be associated with symptoms including dysfunctional beliefs, alexithymia, neurocognitive ability, positive symptoms, and mood symptoms. Groups included individuals with PD (n = 54) and nonpsychiatric controls (n = 55). Participants completed self-report measures of mindfulness and related constructs and clinical interviews of symptoms. Results of ANOVA models indicated that global mindfulness was lower in PD relative to CN, with greatest differences evident for acceptance in the affective psychosis group. Regression models found that greater monitoring was associated with improved neurocognitive performance, while acceptance was associated with lower defeatist beliefs, alexithymia, and depression/anxiety symptoms. Results highlight the importance of targeting acceptance in the psychosocial treatment of PDs, especially for those with mood symptoms.

Modeling intentionality in the human brain

This paper is focusing on a rather neglected issue that concerns both aspects of philosophy and neurobiology in relation to the concept of intentionality. Intentionality is concerned with the 'directedness' or 'aboutness' of mental phenomena towards an object. Despite the fact that in philosophy both concepts of aboutness and directedness are conceptually identical with intentionality, a careful neuroscientific approach can demonstrate that these two phenomena represent two distinct conceptual and neurobiological aspects of intentionality with complementary functions. We described the interaction between a series of intentionality and pathogenetic psychobiological factors, the corresponding brain topography, and the resulting clinical manifestation and psychopathology. A permanent failure of intentionality dominates in psychosis, which includes an inappropriateness of the intentional object or connection, from the outset, or even from the prodromal phase of the disorder. Affective disorders may result from imprecise interoceptive prediction error signals, due to a confused identification of the intentional object. In suicidal patients there is an emotional intentionality failure, characterized by an absence of intentional object or a loss of conscious access to normal intentional objects. We may model an 'intentional system' as a higher order system, with a monitoring and regulatory role attributed to the brain and behavior. Also, we may consider mental disorders as the result of a radical disruption of intentionality, due to an inappropriateness or lack of the intentional object or due to an inappropriate connection in some points of the suggested brain pathways of intentionality.

Dance/movement therapy as a holistic approach to diminish health discrepancies and promote wellness for people with schizophrenia: a review of the literature

Individuals with a diagnosis of schizophrenia face a myriad of obstacles to wellness, beginning with diagnostic discrepancies including over- and misdiagnoses on the schizophrenia spectrum. People with schizophrenia experience profound amounts of stigmatization from the general population, their healthcare providers, and even themselves. Such stigmatization creates a barrier for wellness, poorer prognoses, and often limits adherence to physical and mental healthcare. Moreover, it can exacerbate the already stifling symptomatology of their diagnoses, including specific bodily-related symptomatology. Oftentimes, a diagnosis of schizophrenia disrupts one's relationship with their body including a diminished mind-body connection, decreased interoceptive awareness, and thus unsuccessful intra- and interpersonal relationships. Some recent research suggests the use of mind-body therapies, however, if these practices are internalizing, they may not be appropriate for people with schizophrenia experiencing more acute symptomatology excluding them from treatment. Dance/movement therapy (DMT) is an embodied psychotherapeutic treatment option that can support participants in improving mind-body connection, social relationships, and self-regulatory skill development. Research on DMT has shown promising results for people with schizophrenia, however such research is limited and would benefit from increased studies that particularly measure the effects of DMT on mind-body connection and increased interoception for people with schizophrenia. Moreover, integrative and collaborative treatment models that couple DMT and biofeedback may further our understanding of the physiological and neurological effects of DMT interventions for people with schizophrenia and beyond. This review will examine the recent literature on health inequities for people with schizophrenia, their specific body-based disruptions and needs, and DMT as a promising treatment model, particularly when coupled with biofeedback.

Cortical and subcortical mapping of the allostatic-interoceptive system in the human brain: replication and extension with 7 Tesla fMRI

The brain continuously anticipates the energetic needs of the body and prepares to meet those needs before they arise, a process called allostasis. In support of allostasis, the brain continually models the internal state of the body, a process called interoception. Using published tract-tracing studies in non-human animals as a guide, we previously identified a large-scale system supporting allostasis and interoception in the human brain with functional magnetic resonance imaging (fMRI) at 3 Tesla. In the present study, we replicated and extended this system in humans using 7 Tesla fMRI (N = 91), improving the precision of subgenual and pregenual anterior cingulate topography as well as brainstem nuclei mapping. We verified over 90% of the anatomical connections in the hypothesized allostatic-interoceptive system observed in non-human animal research. We also identified functional connectivity hubs verified in tract-tracing studies but not previously detected using 3 Tesla fMRI. Finally, we demonstrated that individuals with stronger fMRI connectivity between system hubs self-reported greater interoceptive awareness, building on construct validity evidence from our earlier paper. Taken together, these results strengthen evidence for the existence of a whole-brain system supporting interoception in the service of allostasis and we consider the implications for mental and physical health.

Structural connectivity of an interoception network in schizophrenia

Interoception refers to the processing, integration, and interpretation of bodily signals by the brain. Interoception is key to not only basic survival, but also motivational and affective functioning. There is emerging evidence suggesting altered interoception in schizophrenia, but few studies have explored potential neural underpinnings. The current study aims to investigate the anatomical connectivity of a previously identified interoception network in individuals with schizophrenia, and the relationship between network structural connectivity and both emotional functioning and clinical symptoms. Thirty-five participants with schizophrenia (SZ) and 36 healthy control participants (HC) underwent diffusion tensor imaging (DTI) and performed tasks measuring emotional functioning. Probabilistic tractography was used to identify white matter tracts connecting key hubs in an interoception network. Microstructural integrity of these tracts was compared across groups and correlated with measures of emotional functioning and symptom severity. Compared with HC, SZ exhibited altered structural connectivity in the interoception network. In HC, the structural connectivity of the network was significantly correlated with emotion recognition, supporting a link between the interoception network and emotional functioning. However, this correlation was much weaker in SZ. These findings suggest that altered interoception may have implications for illness mechanisms of schizophrenia, especially in relation to emotional deficits.

Multidimensional schizotypy and embodied emotions

Background

Disembodiment and socio-emotional deficits are core features of the schizophrenia spectrum from the prodromal stages to chronic illness. A recent study documented anomalous emotional embodiment in individuals with schizophrenia. Although bodily self disturbances have been shown to precede and predict psychosis onset in at-risk populations, the etiology of anomalous emotional embodiment remains largely unexplored. The present study investigated bodily maps of emotions in relation to schizotypy to extend our understanding of embodied emotions in the schizophrenia spectrum.

Methods

A total of 419 participants (312 female; 19.50 ± 1.22 years) completed a topographical body mapping task where they reported patterns of embodiment experienced in the context of eleven different emotions and a neutral state (EmBODY). Embodied emotions were investigated in relation to multidimensional schizotypy.

Results

Individuals with elevated negative schizotypy experienced embodied emotions with higher intensity (r = 0.16, p = 0.003) but lower clarity (i.e., endorsing activation and deactivation in the same bodily location; β = -0.28, 95% CI [-0.54, -0.03], Z = 2.25, p=0.02) and endorsed more incongruent bodily sensations of emotions (i.e., reporting bodily activation in the context of a low-arousal emotion, r = 0.12, p = 0.05; reporting bodily deactivation in the context of high-arousal emotions, r = 0.13, p = 0.02). In line with the anomalous emotional embodiment documented in individuals with schizophrenia, some of these differences were particularly notable for low-arousal emotions.

Discussion

These results reveal negative schizotypy as a significant correlate of differences in emotional embodiment. More work is needed to link these differences to the anomalous bodily sensations of emotions documented in schizophrenia and assess their functional impact.

The emerging science of Glioception: Contribution of glia in sensing, transduction, circuit integration of interoception

Interoception is the process by which the nervous system regulates internal functions to achieve homeostasis. The role of neurons in interoception has received considerable recent attention, but glial cells also contribute. Glial cells can sense and transduce signals including osmotic, chemical, and mechanical status of extracellular milieu. Their ability to dynamically communicate "listening" and "talking" to neurons is necessary to monitor and regulate homeostasis and information integration in the nervous system. This review introduces the concept of "Glioception" and focuses on the process by which glial cells sense, interpret and integrate information about the inner state of the organism. Glial cells are ideally positioned to act as sensors and integrators of diverse interoceptive signals and can trigger regulatory responses via modulation of the activity of neuronal networks, both in physiological and pathological conditions. We believe that understanding and manipulating glioceptive processes and underlying molecular mechanisms provide a key path to develop new therapies for the prevention and alleviation of devastating interoceptive dysfunctions, among which pain is emphasized here with more focused details.

What is the role of interoception in the symptom experience of people with a chronic condition? A systematic review

BACKGROUND

Interoception, the ability of the organism to sense, interpret, and regulate signals originating from within the body, plays an important role in how individuals perceive and respond to symptoms. However, there is scarce evidence on the role of interoception in the symptom experience of people with chronic conditions.

AIM

To synthesize the role of interoception in the symptom experience of adults with a chronic condition.

METHODS

Systematic review. We searched PubMed, Psychinfo, Embase, CINAHL, and Science Citation Index-Expanded. We included primary research (all study designs) addressing our study aim, published between 2013-2021, and measuring at least one dimension of interoception. Any chronic condition and any symptom were included. No language limits were applied. Only the adult population was included.

RESULTS

We included 18 quantitative studies investigating the relationship between three interoceptive dimensions (i.e., accuracy, sensibility, awareness) and condition-specific symptoms in 10 chronic conditions. People with chronic conditions had lower interoceptive accuracy than healthy controls. Higher interoceptive sensibility was associated with lower symptom severity/frequency. Higher interoceptive accuracy was associated with lower symptom severity/frequency in half of the studies, while the other half reported the opposite. Only one study explored interoceptive awareness.

CONCLUSION

Interoceptive abilities are lower in patients with chronic conditions. Higher interoceptive sensibility is associated with lower symptom severity/frequency, but this relationship is unclear when it comes to interoceptive accuracy and awareness.

Cardiac interoception in patients accessing secondary mental health services: A transdiagnostic study

BACKGROUND

Abnormalities in the regulation of physiological arousal and interoceptive processing are implicated in the expression and maintenance of specific psychiatric conditions and symptoms. We undertook a cross-sectional characterisation of patients accessing secondary mental health services, recording measures relating to cardiac physiology and interoception, to understand how physiological state and interoceptive ability relate transdiagnostically to affective symptoms.

METHODS

Participants were patients (n = 258) and a non-clinical comparison group (n = 67). Clinical diagnoses spanned affective disorders, complex personality presentations and psychoses. We first tested for differences between patient and non-clinical participants in terms of cardiac physiology and interoceptive ability, considering interoceptive tasks and a self-report measure. We then tested for correlations between cardiac and interoceptive measures and affective symptoms. Lastly, we explored group differences across recorded clinical diagnoses.

RESULTS

Patients exhibited lower performance accuracy and confidence in heartbeat discrimination and lower heartbeat tracking confidence relative to comparisons. In patients, greater anxiety and depression predicted greater self-reported interoceptive sensibility and a greater mismatch between performance accuracy and sensibility. This effect was not observed in comparison participants. Significant differences between patient groups were observed for heart rate variability (HRV) although post hoc differences were not significant after correction for multiple comparisons. Finally, accuracy in heartbeat tracking was significantly lower in schizophrenia compared to other diagnostic groups.

CONCLUSIONS

The multilevel characterisation presented here identified certain physiological and interoceptive differences associated with psychiatric symptoms and diagnoses. The clinical stratification and therapeutic targeting of interoceptive mechanisms is therefore of potential value in treating certain psychiatric conditions.

Blunted pupil light reflex is associated with negative symptoms and working memory in individuals with schizophrenia

Two largely separate lines of research have documented altered pupillary dynamics in individuals diagnosed with schizophrenia. An older set of studies has demonstrated reductions in the pupillary light reflex (PLR) in individuals with schizophrenia; however, clinical and cognitive correlates of this blunted PLR have been relatively unexplored. More recently, a large body of work has demonstrated reductions in pupillary dilation in response to cognitive demands in individuals with schizophrenia, and the degree of this blunted pupil dilation has been related to more severe cognitive deficits and motivational negative symptoms. These clinically relevant alterations in the cognitive modulation of pupil size have been interpreted as reflecting insufficient information processing resources or inappropriate effort allocation. To begin to bridge these two lines of work, we investigated the PLR in 34 individuals with schizophrenia and 30 healthy controls and related the amplitude of the PLR to motivational negative symptoms and cognitive performance. Consistent with prior work, we found that the PLR was reduced in individuals with schizophrenia, and furthermore, that these measurements were highly reliable across individuals. Blunted constriction was associated with more severe motivational negative symptoms and poorer working memory among individuals with schizophrenia. These observed correlates provide a bridge between older literature documenting an altered PLR and more recent work reporting associations between negative symptoms, cognition, and blunted pupillary dilation in response to cognitive demands in individuals with schizophrenia. We provide possible mechanistic interpretations of our data and consider a parsimonious explanation for reduced cognitive- and light-related modulation of pupil size.

Interoceptive sensibility and body satisfaction in pregnant and non-pregnant women with and without children

Pregnancy is a time of great physical and psychological change. As well as prominent changes in the external appearance of the body, such as the baby bump, there are also substantial changes taking place within the body. Our awareness of, and attention towards, internal bodily signals (interoception) is thought to have a direct impact on how we feel about our bodies. Therefore, understanding how our experience of these interoceptive signals might change during pregnancy may have important implications for maternal wellbeing. This study examined body satisfaction and interoceptive sensibility (subjective experience of interoception) in pregnant and non-pregnant women with and without children. Feelings towards pregnancy-specific changes in body satisfaction and interoceptive sensibility were also examined in women in their first pregnancy (primigravida) and subsequent pregnancies (multigravida). It was found that pregnancy did not directly impact levels of body satisfaction, instead pregnant and non-pregnant women with children reported less satisfaction with their bodies compared to those without children. Primigravida women were more satisfied with the appearance of pregnancy specific bodily changes compared to multigravida women. Interestingly, these differences in body satisfaction in those with children (pregnant and non-pregnant) were mediated by the extent to which women trusted their bodies (measure of interoceptive sensibility). All other pregnancy related changes in interoceptive sensibility and body satisfaction were either non-significant or had small effect sizes. These results may suggest body trust as an important factor to support during the transition to parenthood in order to improve body satisfaction in mothers.

Deconstructing emotion regulation in schizophrenia: the nature and consequences of abnormalities at the identification stage

Existing evidence suggests that emotion regulation is abnormal in schizophrenia and associated with undesirable clinical outcomes. However, this literature is based predominantly on trait self-report and does not indicate which stages of emotion regulation (identification, selection, implementation) are impaired. The current study focused on determining the nature of abnormalities at the identification stage using ecological momentary assessment (EMA). Participants included clinically stable outpatients with schizophrenia (SZ; n = 48) and healthy controls (CN; n = 52) who completed 6 days of EMA. The EMA surveys assessed emotional experience, emotion regulation, and symptoms. Results indicated that SZ identified the need to regulate at a higher rate than CN. Specifically, SZ displayed an inefficient threshold for identifying the need to regulate, such that they regulated too much when negative affect was low and too little when negative affect was high. Emotion regulation effort exertion was also inefficient, such that effort was too high at low levels of negative affect and too low at high levels of negative affect in SZ. These identification stage abnormalities also demonstrated differential associations with positive and negative symptoms. Findings suggest that identification stage abnormalities may create a bottleneck that feeds forward and impacts subsequent stages of emotion regulation in SZ that are critically related to symptoms. Targeting the psychological processes underlying these identification stage abnormalities might offer a novel means of treating positive and negative symptoms in schizophrenia.

Self-monitoring in schizophrenia: Weighting exteroceptive visual signals against self-generated vestibular cues

Disturbances in self-monitoring are core symptoms of schizophrenia. Some research suggests an over-reliance on exteroceptive cues and a reduced weighting of self-generated interoceptive signals to guide perception. The vestibular sense provides important self-generated information about the body in space. Alterations of vestibular function are reported in schizophrenia, but it is unknown whether internally generated vestibular information is discounted in favour of exteroceptive input. In this study, we test for evidence of an over-reliance on exteroceptive visual cues and a reduced weighting of vestibular signals in guiding perception. In a group of individuals with schizophrenia and healthy controls, we used a well-studied visual illusion - the Tilt Illusion - to probe the respective weight given to visual and vestibular cues in judging line orientation. The Tilt Illusion reveals that perceived orientation of a vertical grating is biased by the orientation in its surround. This illusion increases when the head is tilted, due to the reduced reliability of vestibular information that would otherwise provide an internally generated reference for vertical. We predicted that an over-reliance on exteroceptive cues in schizophrenia would lead to a reduced susceptibility to the effects of head position on Tilt Illusion strength. We find no difference between patients and controls. Both groups show comparable Tilt Illusion magnitudes that increase when the head is tilted. Thus, our findings suggest that chronic patients with schizophrenia adequately combine self-generated vestibular cues and exteroceptive visual input to judge line verticality. A stronger reliance on exteroceptive information over internally generated signals in guiding perception is not evident in our data. Deficits in self-monitoring might therefore be modality specific or state dependant.

Brain-heart interactions are modulated across the respiratory cycle via interoceptive attention

Respiration and heartbeat continuously interact within the living organism at many different levels, representing two of the main oscillatory rhythms of the body and providing major sources of interoceptive information to the brain. Despite the modulatory effect of respiration on exteroception and cognition has been recently established in humans, its role in shaping interoceptive perception has been scarcely investigated so far. In two independent studies, we investigated the effect of spontaneous breathing on cardiac interoception by assessing the Heartbeat Evoked Potential (HEP) in healthy humans. In Study 1, we compared HEP activity for heartbeats occurred during inhalation and exhalation in 40 volunteers at rest. We found higher HEP amplitude during exhalation, compared to inhalation, over fronto-centro-parietal areas. This suggests increased brain-heart interactions and improved cortical processing of the heartbeats during exhalation. Further analyses revealed that this effect was moderated by heart rate changes. In Study 2, we tested the respiratory phase-dependent modulation of HEP activity in 20 volunteers during Exteroceptive and Interoceptive conditions of the Heartbeat Detection (HBD) task. In these conditions, participants were requested to tap at each heartbeat, either listened to or felt, respectively. Results showed higher HEP activity and higher detection accuracy at exhalation than inhalation in the Interoceptive condition only. Direct comparisons of Interoceptive and Exteroceptive conditions confirmed stronger respiratory phase-dependent modulation of HEP and accuracy when attention was directed towards the interoceptive stimuli. Moreover, HEP changes during the Interoceptive condition were independent of heart physiology, but were positively correlated with higher detection accuracy at exhalation than inhalation. This suggests a link between optimization of cortical processing of cardiac signals and detection of heartbeats across the respiratory cycle. Overall, we provide data showing that respiration shapes cardiac interoception at the neurophysiological and behavioural levels. Specifically, exhalation may allow attentional shift towards the internal bodily states.

The relationship between interoception and agency and its modulation by heartbeats: an exploratory study

Interoception, the sense of the internal physiological state of the body, theoretically underpins aspects of self-representation. Experimental studies link feelings of body ownership to interoceptive perception, yet few studies have tested for association between the sense of agency and interoceptive processing. Here, we combined an intentional binding paradigm with cardiac measures of interoceptive processing (behavioural performance on a heartbeat discrimination task, and effects of timing within the cardiac cycle) in twenty-six non-clinical participants as an exploratory study. We found performance accuracy on the heartbeat discrimination task correlated positively with the intentional binding effect, an index of sense of agency (β = 0.832, p = 0.005), even after controlling for effects of age, sex, educational level, heart rate, heart rate variability and time accuracy. The intentional binding effect was enhanced during cardiac systole (compared to diastole) in individuals with greater heartbeat discrimination accuracy (β = 0.640, p = 0.047). These findings support the proposal that interoception contributes to mechanisms underlying the emergence of sense of agency.

Interoceptive pathways to understand and treat mental health conditions

An increasing recognition that brain and body are dynamically coupled has enriched our scientific understanding of mental health conditions. Peripheral signals interact centrally to influence how we think and feel, generating our sense of the internal condition of the body, a process known as interoception. Disruptions to this interoceptive system may contribute to clinical conditions, including anxiety, depression, and psychosis. After reviewing the nature of interoceptive disturbances in mental health conditions, this review focuses on interoceptive pathways of existing and putative mental health treatments. Emerging clinical interventions may target novel peripheral treatment mechanisms. Future treatment development requires forward- and back-translation to uncover and target specific interoceptive processes in mental health to elucidate their efficacy relative to interventions targeting other factors.

Decreased interoceptive accuracy in children with autism spectrum disorder and with comorbid attention deficit/hyperactivity disorder

Interoception refers to the awareness of internal physiological state. Several previous studies reported that people with autism spectrum disorders (ASD) and adults with attention-deficit/hyperactivity disorder (ADHD) have diverse patterns of interoception, but the extent of literature is limited and inconsistent. This study aimed to investigate the interoceptive accuracy (IA) in children with ASD, children with comorbid ASD and ADHD, and typically developing (TD) children with high and low levels of autistic traits. We administered the eye-tracking interoceptive accuracy task (EIAT) to 30 children with ASD, 20 children with comorbid ASD and ADHD, and 63 TD controls with high and low levels of autistic traits. Parent-report scales concerning ASD and ADHD symptoms were collected. ASD children with and without comorbid ADHD both exhibited lower IA than TD children. Reduced IA was also found in TD children with high-autistic traits relative to those with low-autistic traits. IA was negatively correlated with autistic and ADHD symptoms. Atypical cardiac interoception could be found in children with ASD. Difficulties in sensing and comprehending internal bodily signals in childhood may be related to both ASD and ADHD symptoms.

Interoceptive functioning in schizophrenia and schizotypy

Though bodily self-disturbances are well documented in schizophrenia, interoceptive functioning (i.e., the perception of the internal state of the body) remains poorly understood in this population. In fact, only two studies to date have empirically measured interoceptive ability in schizophrenia. Both studies documented a deficit in interoceptive accuracy (i.e., the objective performance on a heartbeat detection task), and one noted differences in interoceptive sensibility (i.e., the subjective experience of interoception) in this population. To our knowledge, interoceptive awareness (i.e., the metacognitive awareness of one's interoceptive ability) has never been measured in schizophrenia and the link between interoceptive functioning and schizotypy remains unexplored. The present study addresses this gap by investigating the three dimensions of interoception in individuals with schizophrenia and matched controls (Experiment 1, N = 58) and in relation to schizotypal traits (Experiment 2, N = 109). Consistent with the literature, Experiment 1 documented a deficit in interoceptive accuracy and differences in interoceptive sensibility in individuals with schizophrenia. For the first time, our study revealed intact interoceptive awareness in individuals with schizophrenia. Against our expectations, we found no link between schizotypy and interoceptive functioning in Experiment 2. Our novel findings bear important clinical implications as insight into one's interoceptive limitations (i.e., intact interoceptive awareness) might promote treatment seeking behavior in schizophrenia. The lack of association between interoceptive ability and schizotypy in non-help-seeking youths suggests that changes in interoception may only arise with the onset of psychosis.

The Transdiagnostic Relevance of Self-Other Distinction to Psychiatry Spans Emotional, Cognitive and Motor Domains

Self-other distinction refers to the ability to distinguish between our own and other people's physical and mental states (actions, perceptions, emotions etc.). Both the right temporo-parietal junction and brain areas associated with the human mirror neuron system are likely to critically influence self-other distinction, given their respective contributions to theory of mind and embodied empathy. The degree of appropriate self-other distinction will vary according to the exact social situation, and how helpful it is to feel into, or remain detached from, another person's mental state. Indeed, the emotional resonance that we can share with others affords the gift of empathy, but over-sharing may pose a downside, leading to a range of difficulties from personal distress to paranoia, and perhaps even motor tics and compulsions. The aim of this perspective paper is to consider how evidence from behavioral and neurophysiological studies supports a role for problems with self-other distinction in a range of psychiatric symptoms spanning the emotional, cognitive and motor domains. The various signs and symptoms associated with problematic self-other distinction comprise both maladaptive and adaptive (compensatory) responses to dysfunction within a common underlying neuropsychological mechanism, compelling the adoption of more holistic transdiagnostic therapeutic approaches within Psychiatry.

Sex differences in interoceptive accuracy: A meta-analysis

Interoceptive accuracy, the ability to correctly perceive internal signals arising from the body, is thought to be disrupted in numerous mental and physical health conditions. Whilst evidence suggests poorer interoceptive accuracy in females compared to males, raising the possibility that interoceptive differences may relate to sex differences in mental and physical health, results concerning sex differences in interoceptive accuracy are mixed. Given such ambiguity, this meta-analysis aimed to establish the presence or absence of sex differences in interoceptive accuracy across cardiac, respiratory, and gastric domains. A review of 7956 abstracts resulted in 93 eligible studies. Results demonstrated superior accuracy in males across cardiac, but not gastric, tasks, while findings on respiratory tasks were mixed. Effect sizes were consistent across cardiac tasks, but instability and/or moderate heterogeneity was observed across other domains, likely due to the small number of eligible studies. Despite such limitations, results indicate the possibility of sex differences across interoception tasks and domains. Methodological limitations concerning the influence of physiological factors, and directions for future research are discussed.

Interoception abnormalities in schizophrenia: A review of preliminary evidence and an integration with Bayesian accounts of psychosis

Schizophrenia research has traditionally focused almost exclusively on how the brain interprets the outside world. However, our internal bodily milieu is also central to how we interpret the world and construct our reality: signals from within the body are critical for not only basic survival, but also a wide range of brain functions from basic perception, emotion, and motivation, to sense of self. In this article, we propose that interoception-the processing of bodily signals-may have implications for a wide range of clinical symptoms in schizophrenia and may thus provide key insights into illness mechanisms. We start with an overview of interoception pathways. Then we provide a review of direct and indirect findings in various interoceptive systems in schizophrenia and interpret these findings in the context of computational frameworks that model interoception as hierarchical Bayesian inference. Finally, we propose a conceptual model of how altered interoceptive inference may contribute to specific schizophrenia symptoms-negative symptoms in particular-and suggest directions for future research, including potential new avenues of treatment.

The Role of Interoceptive Attention and Appraisal in Interoceptive Regulation

Interoception, i.e., the processing and integration of sensory information has gained research interest due to its relevance in the psychopathological context. In the present review, we focus upon interoceptive regulation or one’s capacity to match bodily signals to his/her desired state by altering the signal or the desired state. More specifically, we discuss attention toward and appraisal of interoceptive stimuli as regulatory mechanisms of interoception. We review findings in the emerging research area of interoceptive attention. Studies suggest that the quality of attention and the nature of appraisal regarding interoceptive information influence interoceptive regulation and subsequent adaptive or maladaptive behavioral strategies among healthy controls as well as clinical populations. We discuss the clinical implications and the need to promote further research as well as to target interoceptive attention and appraisal mechanisms in psychotherapy.

Development and validation of the Interoceptive States Static Images (ISSI) database

Internal bodily signals provide an essential function for human survival. Accurate recognition of such signals in the self, known as interoception, supports the maintenance of homeostasis, and is closely related to emotional processing, learning and decision-making, and mental health. While numerous studies have investigated interoception in the self, the recognition of these states in others has not been examined despite its crucial importance for successful social relationships. This paper presents the development and validation of the Interoceptive States Static Images (ISSI), introducing a validated database of 423 visual stimuli for the study of non-affective internal state recognition in others, freely available to other researchers. Actors were photographed expressing various exemplars of both interoceptive states and control actions. The images went through a two-stage validation procedure, the first involving free-labelling and the second using multiple choice labelling and quality rating scales. Five scores were calculated for each stimulus, providing information about the quality and specificity of the depiction, as well as the extent to which labels matched the intended state/action. Results demonstrated that control action stimuli were more recognisable than internal state stimuli. Inter-category variability was found for the internal states, with some states being more recognisable than others. Recommendations for the utilisation of ISSI stimuli are discussed. The stimulus set is freely available to researchers, alongside data concerning recognisability.

Interoception and Obsessive-Compulsive Disorder: A Review of Current Evidence and Future Directions

Disrupted interoceptive processes are present in a range of psychiatric conditions, and there is a small but growing body of research on the role of interoception in obsessive-compulsive disorder (OCD). In this review, we outline dimensions of interoception and review current literature on the processing of internal bodily sensations within OCD. Investigations in OCD utilizing objective measures of interoception are limited and results mixed, however, the subjective experience of internal bodily sensations appears to be atypical and relate to specific patterns of symptom dimensions. Further, neuroimaging investigations suggest that interoception is related to core features of OCD, particularly sensory phenomena and disgust. Interoception is discussed in the context of treatment by presenting an overview of existing interventions and suggesting how modifications aimed at better targeting interoceptive processes could serve to optimize outcomes. Interoception represents a promising direction for multi-method research in OCD, which we expect, will prove useful for improving current interventions and identifying new treatment targets.

Measuring interoception: The phase adjustment task

Interoception, perception of one's bodily state, has been associated with mental health and socio-emotional processes. However, several interoception tasks are of questionable validity, meaning associations between interoception and other variables require confirmation with new measures. Here we describe the novel, smartphone-based Phase Adjustment Task (PAT). Tones are presented at the participant's heart rate, but out of phase with heartbeats. Participants adjust the phase relationship between tones and heartbeats until they are synchronous. Data from 124 participants indicates variance in performance across participants which is not affected by physiological or strategic confounds. Associations between interoception and anxiety, depression and stress were not significant. Weak associations between interoception and mental health variables may be a consequence of testing a non-clinical sample. A second study revealed PAT performance to be moderately stable over one week, consistent with state effects on interoception.

The Emerging Science of Interoception: Sensing, Integrating, Interpreting, and Regulating Signals within the Self

Interoception refers to the representation of the internal states of an organism, and includes the processes by which it senses, interprets, integrates, and regulates signals from within itself. This review presents a unified research framework and attempts to offer definitions for key terms to describe the processes involved in interoception. We elaborate on these definitions through illustrative research findings, and provide brief overviews of central aspects of interoception, including the anatomy and function of neural and non-neural pathways, diseases and disorders, manipulations and interventions, and predictive modeling. We conclude with discussions about major research gaps and challenges.

Interoception Disorder and Insular Cortex Abnormalities in Schizophrenia: A New Perspective Between Psychoanalysis and Neuroscience

The existence of disturbances in the perception of somatic states and in the representation of the body with the presence of cœnesthetic hallucinations, of delusional hypochondriac ideas or of dysmorphophobias is a recognized fact in the psychopathology of schizophrenia. Freudian psychoanalytic theory had accorded a privileged place to the alteration of the perception of the body in schizophrenia. Freud had attributed to these phenomena a primary and prodromal role in the psychopathology of psychosis. We propose to look at this theory in a new way, starting from the perspective of recent studies about the role of the insula in the perception and representation of somatic states, since this structure has been identified as underpinning the sense of interoception. The data in the neurobiological literature about abnormalities in the insular cortex in schizophrenia has shown that insula dysfunction could constitute one of the biological substrates of disorders of body perception in schizophrenia, and could be a source of the alteration of the sense of self that is characteristic of this psychiatric pathology. Moreover, this alteration could thus be involved in the positive symptomatology of schizophrenia.

The inside of me: interoceptive constraints on the concept of self in neuroscience and clinical psychology

Humans are unique in their ability to think about themselves and carry a more or less clear notion of who they are in their mind. Here we review recent evidence suggesting that the birth, maintenance, and loss of the abstract concept of 'self' is deeply tied to interoception, the sense of internal physiological signals. Interoception influences multiple facets of the self-concept, cutting across its material, social, moral, and agentive components. Overall, we argue that interoception contributes to the stability of the self-concept over time, unifying its layers and constraining the degree to which it is susceptible to external influences. Hence, the core features of the self-concept are those that correlate more with inner bodily states. We discuss the implications that this may have for theories of embodied cognition as well as for the understanding of psychiatric disorders in which the concept of self appears fragmented or loose. Finally, we formulate some empirical predictions that could be tested in future studies to shed further light on this emerging field.

[The role of structural and functional insular cortex abnormalities in body perception disturbance in schizophrenia]

OBJECTIVES

The present study focuses on a review of scientific literature upon structural and functional abnormalities of the insular cortex found in schizophrenic patients in order to emphasize links between the pathophysiology of this brain region and the symptomatology of schizophrenia.

METHODS

From a review based upon journal articles published since 2002 and indexed into the Pubmed data base, we first studied the main findings on the function of the insular cortex and its involvement in the perception and representation of the body states, as it is one of the main neural substrates for the interoception sense. Then, we highlighted various structural abnormalities found in schizophrenic patients in order to study links existing between dysfunctions in the insular cortex and an altered perception of body states and of self-awareness in schizophrenia. Eventually, we studied the links emphasized between functional abnormalities of insula in schizophrenia and a positive symptomatology, especially auditory hallucinations.

RESULTS

The data in the neurobiological literature about abnormalities in the insular cortex in schizophrenia has demonstrated that insula dysfunctions could constitute one of the biological substrates of disorders of body perception in schizophrenia, and it could be a source of the alteration of the sense of self that is characteristic of this psychiatric pathology. Moreover, the importance of insula in processing interoceptive stimuli and their integration with exteroceptive stimuli could engender a problem in the discrimination between endogenic and exogenic stimuli, a problem that could thus be involved in the positive symptomatology of schizophrenia, such as auditory hallucinations and delusion.

CONCLUSIONS

Scientific knowledge in the role of the insula for the perception and representation of the body states shows that the insula has a key role for interoception. Functional abnormalities of the insular cortex in schizophrenia may lead to the conclusion that this area of the brain is one of the biological substrates for the disorders of body perception in schizophrenia, and also, mainly, one of the substrates for the disorders of self-awareness which depends, according to many authors, on the representation of the body states. Moreover, the role of the insula in integrating interoceptive and exteroceptive stimuli leads to the supposition that dysfunctions of the insula could result in a problem concerning the discrimination between endogenic and exogenic stimuli, and thus could create a positive symptomatology, mainly auditory hallucinations for schizophrenic patients. It needs to be noted that the links between the symptomatology of schizophrenia and the dysfunctions of the insular cortex are still in debate among researchers. Recent researches do not allow to conclude with accuracy of a systematic correlation between psychopathology of schizophrenia and functional abnormalities of the insula, although it seems obvious to find a link between these psychopathological and neurobiological phenomena.

Bodily Self-Disturbances in Schizophrenia: A Comparative Study of South Korea and the USA

BACKGROUND

Bodily self-disturbances are highly salient to the phenomenology of schizophrenia (SZ) but difficult to quantify owing to the subjective nature of these experiences that challenge verbal descriptions. The Benson et al. [PsyCh J. 2019 Mar;8(1):110-21] Body Disturbances Inventory (B-BODI) provides visual aids to help participants access the frequency, distressfulness, and vividness of subjective self-experiences with good reliability and validity in North American samples. However, the concept of the self and, accordingly, the conceptualization of self-disorders are influenced by culture. Therefore, we examined self-disturbances in individuals with SZ and control (CO) participants in 2 distinct cultures.

METHODS

B-BODI was administered to South Korean and North American participants, with and without SZ. Severity of symptoms in diagnosed individuals with SZ and schizotypy in CO was assessed. We also assessed perceived social isolation and mood in all participants.

RESULTS

Endorsement and frequency of bodily self-disturbances in SZ were similar in both cultures. In contrast, there were significant cultural differences in the degree of distress and vividness of self-disturbances. Bodily self-disturbances were experienced as more vivid and distressing to Americans than Koreans, regardless of diagnosis. For both cultures, B-BODI scores were associated with positive, but not negative, symptoms in SZ. For CO, elevated schizotypy was associated with B-BODI scores. Mood and loneliness were not associated with B-BODI scores.

CONCLUSION

SZ reported overall increased levels of bodily self-disturbances compared with CO, regardless of culture. However, there were cultural differences in one's emotional reaction to these experiences. Americans were more distressed by self-disturbances and experienced them more vividly than Koreans. These findings suggest that Americans may be less accepting of anomalous bodily self-experiences relative to Koreans. Last, B-BODI appears to be a useful tool for future cross-cultural studies of SZ phenomenology.

Dimensions of interoception in obsessive-compulsive disorder

Interoceptive sensibility (IS) refers to the subjective experience of perceiving and being aware of one's internal body sensations, and is typically evaluated using self-report questionnaires or confidence ratings. Here we evaluated IS in 81 patients with OCD and 76 controls using the Multidimensional Scale of Interoceptive Awareness (MAIA), which contains 8 subscales assessing adaptive and maladaptive responses to sensation. Compared to controls, OCD patients showed hyperawareness of body sensations. Patients also demonstrated a more maladaptive profile of IS characterized by greater distraction from and worry about unpleasant sensations, and reduced tendency to experience the body as safe and trustworthy. These findings were independent of medication status and comorbidities in the patient group. Correlational analyses showed that subscales of the MAIA were differentially associated with OCD symptom dimensions. These findings indicate that patients with OCD show abnormality of IS that is independent of confounding factors related to medication and comorbidities and associated with different OCD symptom dimensions. Future work would benefit from examining neural correlates of these effects and evaluating whether dimensions of IS are impacted by treatments for the disorder.

Time Processing, Interoception, and Insula Activation: A Mini-Review on Clinical Disorders

Time processing is a multifaceted skill crucial for managing different aspects of life. In the current work, we explored the relationship between interoception and time processing by examining research on clinical models. We investigated whether time processing deficits are associated with dysfunction of the interoceptive system and/or insular cortex activity, which is crucial in decoding internal body signaling. Furthermore, we explored whether insular activation predicts the subjective experience of time (i.e., the subjective duration of a target stimulus to be timed). Overall, our work suggests that alteration of the interoceptive system could be a common psychophysiological hallmark of mental disorders affected by time processing deficits.

Insula functional connectivity in schizophrenia

The insula is structurally abnormal in schizophrenia, demonstrating reductions in volume, cortical thickness, and altered gyrification during prodromal, early and chronic stages of the illness. Despite compelling structural alterations, less is known about its functional connectivity, limited by studies considering the insula as a whole or only within the context of resting-state networks. There is evidence, however, from healthy subjects that the insula is comprised of sub-regions with distinct functional profiles, with dorsal anterior insula (dAI) involved in cognitive processing, ventral anterior insula (vAI) involved in affective processing, and posterior insula (PI) involved in somatosensory processing. The current study builds on this prior work and characterizes insula resting-state functional connectivity sub-region profiles in a large cohort of schizophrenia (N = 191) and healthy (N = 196) participants and hypothesizes specific associations between insula sub-region connectivity abnormalities and clinical characteristics related to their functional profiles. Functional dysconnectivity of the insula in schizophrenia is broadly characterized by reduced connectivity within insula sub-networks and greater connectivity with regions not normally connected with that sub-region, reflected in significantly greater similarity of dAI and PI connectivity profiles and significantly lower similarity of dAI and vAI connectivity profiles (p < .05). In schizophrenia, reduced connectivity of dAI correlates with cognitive function (r = 0.18, p = .014), whereas stronger connectivity between vAI and superior temporal sulcus correlates with negative symptoms (r = 0.27, p < .001). These findings reveal altered insula connectivity in all three sub-regions and converge with recent evidence of reduced differentiation of insula connectivity in schizophrenia, implicating functional dysconnectivity of the insula in cognitive and clinical symptoms.

Anomalous Bodily Maps of Emotions in Schizophrenia

OBJECTIVE

Embodied emotions arise from interoceptive and somatosensory processes, and are essential to the development of a stable sense of self. Emotional embodiment is therefore inherently interwoven with our sense of bodily self-awareness, and allows us to navigate complex social situations. Given that the core feature of schizophrenia (SZ) is characterized by the presence of bodily self-disturbances and social-emotional deficits, we hypothesized that embodiment of emotion would be disrupted in SZ.

METHOD

Twenty-six medicated individuals with SZ and 26 demographically matched controls used a computerized topographical mapping tool ("EmBODY") to indicate on a body outline where they felt bodily sensations while experiencing an emotion. There were 13 different emotions plus a neutral state. The resulting bodily maps of emotions were quantitatively compared between groups using linear discriminant analysis and similarity scores.

RESULTS

Bodily maps of emotions were anomalous in SZ as indicated by indistinguishable maps across different emotions. Relative to the control group, patients reported less discrete and less clear bodily sensations across emotions. In particular, bodily maps for low-arousal emotions were atypical in comparison with healthy controls.

CONCLUSIONS

Anomalous and undifferentiated mapping of embodied emotions in SZ could lead to deficits in linking bodily sensations to conceptual categories of emotions. Disrupted emotional embodiment could also contribute to poor social functioning. Abnormal bodily sensations of emotions might therefore be a promising target for future psychosocial interventions.

Brain-based ranking of cognitive domains to predict schizophrenia

Schizophrenia is a devastating brain disorder that disturbs sensory perception, motor action, and abstract thought. Its clinical phenotype implies dysfunction of various mental domains, which has motivated a series of theories regarding the underlying pathophysiology. Aiming at a predictive benchmark of a catalog of cognitive functions, we developed a data-driven machine-learning strategy and provide a proof of principle in a multisite clinical dataset (n = 324). Existing neuroscientific knowledge on diverse cognitive domains was first condensed into neurotopographical maps. We then examined how the ensuing meta-analytic cognitive priors can distinguish patients and controls using brain morphology and intrinsic functional connectivity. Some affected cognitive domains supported well-studied directions of research on auditory evaluation and social cognition. However, rarely suspected cognitive domains also emerged as disease relevant, including self-oriented processing of bodily sensations in gustation and pain. Such algorithmic charting of the cognitive landscape can be used to make targeted recommendations for future mental health research.

Autism and psychosis as diametrical disorders of embodiment

Humans have evolved an elaborate system of self-consciousness, self-identity, self-agency, and self-embodiment that is grounded in specific neurological structures including an expanded insula. Instantiation of the bodily self has been most-extensively studied via the 'rubber hand illusion', whereby parallel stimulation of a hidden true hand, and a viewed false hand, leads to the felt belief that the false hand is one's own. Autism and schizophrenia have both long been regarded as conditions centrally involving altered development of the self, but they have yet to be compared directly with regard to the self and embodiment. Here, we synthesize the embodied cognition literature for these and related conditions, and describe evidence that these two sets of disorders exhibit opposite susceptibilities from typical individuals to the rubber hand illusion: reduced on the autism spectrum and increased in schizophrenia and other psychotic-affective conditions. Moreover, the opposite illusion effects are mediated by a consilient set of associated phenomena, including empathy, interoception, anorexia risk and phenotypes, and patterns of genetic correlation. Taken together, these findings: (i) support the diametric model of autism and psychotic-affective disorders, (ii) implicate the adaptive human system of self-embodiment, and its neural bases, in neurodevelopmental disorders, and suggest new therapies and (iii) experimentally ground Bayesian predictive coding models with regard to autism compared with psychosis. Lay summary: Humans have evolved a highly developed sense of self and perception of one's own body. The 'rubber hand illusion' can be used to test individual variation in sense of self, relative to connection with others. We show that this illusion is reduced in autism spectrum disorders, and increased in psychotic and mood disorders. These findings have important implications for understanding and treatment of mental disorders.

The Role of Language in Alexithymia: Moving Towards a Multiroute Model of Alexithymia

Alexithymia is characterized by difficulty identifying and describing one’s own emotion. Identifying and describing one’s emotion involves several cognitive processes, so alexithymia may result from a number of impairments. Here we propose the alexithymia language hypothesis—the hypothesis that language impairment can give rise to alexithymia—and critically review relevant evidence from healthy populations, developmental disorders, adult-onset illness, and acquired brain injury. We conclude that the available evidence is supportive of the alexithymia–language hypothesis, and therefore that language impairment may represent one of multiple routes to alexithymia. Where evidence is lacking, we outline which approaches will be useful in testing this hypothesis.