Interoception in anxiety and depression

Disentangling the nature of the nicotine stimulus

Learning involving interoceptive stimuli likely plays an important role in many diseases and psychopathologies. Within this area, there has been extensive research investigating the interoceptive stimulus effects of abused drugs. In this pursuit, behavioral pharmacologists have taken advantage of what is known about learning processes and adapted the techniques to investigate the behavioral and receptor mechanisms of drug stimuli. Of particular interest is the nicotine stimulus and the use of the two-lever operant drug discrimination task and the Pavlovian drug discriminated goal-tracking task. There is strong concordance between the two methods when using "standard" testing protocols that minimize learning on test days. For example, ABT-418, nornicotine, and varenicline all fully evoked nicotine-appropriate responding. Notably, research from our laboratory with the discriminated goal-tracking task has used an alternative testing protocol. This protocol assesses stimulus substitution based on how well extinction learning using a non-nicotine ligand transfers back to the nicotine stimulus. These findings challenge conclusions based on more "standard" testing procedures (e.g., ABT-418 is not nicotine-like). As a starting point, we propose Thurstone scaling as a quantitative method for more precisely comparing transfer of extinction across doses, experiments, and investigators. We close with a discussion of future research directions and potential implications of the research for understanding interoceptive stimuli.

How Emotions Are Shaped by Bodily States

The state of the body is central to guiding motivational behaviours. Here we discuss how afferent information from face and viscera influence the processing and communication of emotional states. We highlight (a) the fine-grained impact that facial muscular and patterned visceral responses exert on emotional appraisal and communicative signals; (b) short-term changes in visceral state that bias brain responses to emotive stimuli; (c) the commonality of brain pathways and substrates mediating short- and long-term bodily effects on emotional processes; (d) how topographically distinct representations of different bodily states are coupled to reported feelings associated with subtypes of disgust; and (e) how pupil signals contribute to affective exchange. Integrating these observations enriches our understanding of emotional processes and psychopathology.

Depression in cultural context: "Chinese somatization," revisited

We have presented a view of culture and mental health that builds on work in cultural psychiatry, anthropology, and cultural psychology, and applied it to research on culture and depression. In particular, we have returned to the well-known topic of Chinese somatization. A culture–mind–brain approach to these questions helps us think about them in a way that points toward new research. We have applied this approach to thinking about a single set of questions, relevant to a single (DSM-based) diagnosis, in a single cultural group. The potential, however, is to rethink how we conceptualize mental health in ways consistent with cultural psychiatry’s general perspective over the past several decades, while incorporating rather than rejecting the many recent advances in brain and behavior sciences. In so doing, we gain a more expanded and nuanced view of the global landscape of mental health, accompanied by a more expanded and nuanced view of individual patients.

Subjecting elite athletes to inspiratory breathing load reveals behavioral and neural signatures of optimal performers in extreme environments

Background

It is unclear whether and how elite athletes process physiological or psychological challenges differently than healthy comparison subjects. In general, individuals optimize exercise level as it relates to differences between expected and experienced exertion, which can be conceptualized as a body prediction error. The process of computing a body prediction error involves the insular cortex, which is important for interoception, i.e. the sense of the physiological condition of the body. Thus, optimal performance may be related to efficient minimization of the body prediction error. We examined the hypothesis that elite athletes, compared to control subjects, show attenuated insular cortex activation during an aversive interoceptive challenge.

Methodology/Principal Findings

Elite adventure racers (n = 10) and healthy volunteers (n = 11) performed a continuous performance task with varying degrees of a non-hypercapnic breathing load while undergoing functional magnetic resonance imaging. The results indicate that (1) non-hypercapnic inspiratory breathing load is an aversive experience associated with a profound activation of a distributed set of brain areas including bilateral insula, dorsolateral prefrontal cortex and anterior cingulated; (2) adventure racers relative to comparison subjects show greater accuracy on the continuous performance task during the aversive interoceptive condition; and (3) adventure racers show an attenuated right insula cortex response during and following the aversive interoceptive condition of non-hypercapnic inspiratory breathing load.

Conclusions/Significance

These findings support the hypothesis that elite athletes during an aversive interoceptive condition show better performance and an attenuated insular cortex activation during the aversive experience. Interestingly, differential modulation of the right insular cortex has been found previously in elite military personnel and appears to be emerging as an important brain system for optimal performance in extreme environments.

Anatomical and functional overlap within the insula and anterior cingulate cortex during interoception and phobic symptom provocation

The anterior insula and the dorsal anterior cingulate cortex (ACC) are regarded as key brain structures associated with the integration of perceived phobic characteristics of external stimuli and the perception of ones own body responses that leads to emotional feelings. To test to what extent the activity in these two brain structures anatomically and functionally overlap during phobic reactions and interoception, we submitted the same group of phobic participants (n = 29; either spider or blood-injection-injury (BII) phobics) and controls (n = 17) to both type of experimental paradigms. Results showed that there was a clear anatomical overlap in the Blood Oxygen Level-Dependent (BOLD) responses within the anterior insula and ACC elicited during phobic symptom provocation and during interoceptive awareness. The activity within these two brain structures also showed to be correlated in the spider phobia group, but not in the BII phobic participants. Our results seem to support the idea that the activity within these two brain areas would be associated with the integration of perceived stimuli characteristics and bodily responses that lead to what we label as "fear." However, that seems not to be the case in BII phobia, where more research is needed in order to clarify to what extent that could be associated with the idiosyncratic physiological response that these patients present in front of phobic stimuli (i.e., drop in heart rate and blood pressure).

Anxiety symptom presentations in Han Chinese and Euro-Canadian outpatients: is distress always somatized in China?

BACKGROUND

Cultural variations in the relative emphasis on somatic versus psychological symptoms of distress are a common topic in cultural psychopathology. The most well-known example involves people of Chinese heritage, who are found to emphasize somatic symptoms in presenting depression as compared with people of Western European heritage. It remains unknown whether a similar cultural difference is found for anxiety disorders.

METHODS

Euro-Canadian (n=79) and Han Chinese (n=154) psychiatric outpatients with clinically significant concerns about both depression and anxiety were selected from a larger dataset based on their responses to a structured interview. They also completed two self-report questionnaires assessing somatization of depression and anxiety.

RESULTS

As expected, Chinese participants reported a greater tendency to emphasize somatic symptoms of depression, as compared to the Euro-Canadians. Contrary to expectations, the tendency to emphasize somatic symptoms of anxiety was higher among the Euro-Canadians as compared to the Chinese participants.

LIMITATIONS

Characteristics of our participants limit the generalizability of our findings. The current study is preliminary and requires replication.

CONCLUSIONS

Despite the exploratory nature of this study, the results suggest that the popular notion of 'Chinese somatization' should not be over-generalized. Our findings also imply that there may be important differences in the cultural understanding of depression and anxiety in both Chinese and 'Western' contexts. Future studies should seek to unpack potential cultural explanations for why Euro-Canadian outpatients may emphasize somatic symptoms in the presentation of anxiety to a greater degree than Chinese outpatients.

Self-rating scales assessing subjective well-being and distress correlate with rCBF in PTSD-sensitive regions

BACKGROUND

The aim of this study was to investigate the distribution of the regional cerebral blood flow (rCBF) in occupational-related post-traumatic stress disorder (PTSD) subjects and to seek possible correlations between brain perfusion and self-rating scales (SRS) in order to cross-check their diagnostic value and to look for their neural correlates.

METHOD

A total of 13 traumatized underground and long-distance train drivers developing (S) and 17 not developing (NS) PTSD who had experienced a 'person under train' accident or who had been assaulted at work underwent clinical assessment and 99mTc-HMPAO SPECT imaging during autobiographical trauma scripts. Statistical parametric mapping was applied to analyse rCBF changes in S as compared with NS and to search for correlations between rCBF and the administered SRS scores, modelling age, months to SPECT and the ratio 'grey matter/intra-cranial volume' as nuisance variables.

RESULTS

Significantly higher activity was observed during trauma script in left posterior and anterior insula, posterior cingulate, inferior parietal lobule, precuneus, caudate and putamen in PTSD subjects as compared with the trauma-exposed control group. Impact of Event Scale and World Health Organisation (10) Well-Being Index scores highly correlated with tracer uptake to a great extent in the same regions in which rCBF differences between S and NS were found.

CONCLUSIONS

These findings support the involvement of insular, cingulate and parietal cortices (as well as the basal ganglia) in the pathogenesis of PTSD and in the processing of related subjective well-being and distress.

Body integrity identity disorder: deranged body processing, right fronto-parietal dysfunction, and phenomenological experience of body incongruity

Body integrity identity disorder (BIID) is characterised by profound experience of incongruity between the biological and desired body structure. The condition manifests in "non-belonging" of body parts, and the subsequent desire to amputate, paralyse or disable a limb. Little is known about BIID; however, a neuropsychological model implicating right fronto-parietal and insular networks is emerging, with potential disruption to body representation. We argue that, as there is scant systematic research on BIID published to date and much of the research is methodologically weak, it is premature to assume that the only process underlying bodily experience that is compromised is body representation. The present review systematically investigates which aspects of neurological processing of the body, and sense of self, may be compromised in BIID. We argue that the disorder most likely reflects dysregulation in multiple levels of body processing. That is, the disunity between self and the body could arguably come about through congenital and/or developmental disruption of body representations, which, together with altered multisensory integration, may preclude the experience of self-attribution and embodiment of affected body parts. Ulimately, there is a need for official diagnostic criteria to facilitate epidemiological characterisation of BIID, and for further research to systematically investigate which aspects of body representation and processing are truly compromised in the disorder.

Insula reactivity and connectivity to anterior cingulate cortex when processing threat in generalized social anxiety disorder

Aberrant subcortical-prefrontal connectivity may contribute to insula hyper-reactivity to threat in generalized social anxiety disorder (gSAD). A novel PsychoPhysiological Interaction (PPI) analysis was used to examine functional 'coupling' between the insula and prefrontal cortex in gSAD patients and healthy controls (HCs). During fMRI, 29 gSAD and 26 HC volunteers performed an Emotional Face Matching Task, involving the processing of fear, angry, and happy expressions. As expected, compared with HCs, gSAD patients exhibited greater bilateral anterior insula (aINS) reactivity for fear vs. happy faces; this group difference was less robust for angry vs. happy faces. PPI of insula connectivity when processing fearful faces revealed the gSAD group had less right aINS-dorsal anterior cingulate coupling compared to HCs. Findings indicate that aINS hyper-reactivity for fear faces in gSAD, compared to controls, involves reduced connectivity with a prefrontal region implicated in cognitive control and emotion regulation.

The shopping brain: math anxiety modulates brain responses to buying decisions

Metacognitive theories propose that consumers track fluency feelings when buying, which may have biological underpinnings. We explored this using event-related potential (ERP) measures as twenty high-math anxiety (High MA) and nineteen low-math anxiety (Low MA) consumers made buying decisions for promoted (e.g., 15% discount) and non-promoted products. When evaluating prices, ERP correlates of higher perceptual and conceptual fluency were associated with buys, however only for High MA females under no promotions. In contrast, High MA females and Low MA males demonstrated greater FN400 amplitude, associated with enhanced conceptual processing, to prices of buys relative to non-buys under promotions. Concurrent late positive component (LPC) differences under no promotions suggest discrepant retrieval processes during price evaluations between consumer groups. When making decisions to buy or not, larger (smaller) P3, sensitive to outcome responses in the brain, was associated with buying for High MA females (Low MA females) under promotions, an effect also present for males under no promotions. Thus, P3 indexed decisions to buy differently between anxiety groups, but only for promoted items among females and for no promotions among males. Our findings indicate that perceptual and conceptual processes interact with anxiety and gender to modulate brain responses during consumer choices.

Identification of neural targets for the treatment of psychiatric disorders: the role of functional neuroimaging

Neurosurgical treatment of psychiatric disorders has been influenced by evolving neurobiological models of symptom generation. The advent of functional neuroimaging and advances in the neurosciences have revolutionized understanding of the functional neuroanatomy of psychiatric disorders. This article reviews neuroimaging studies of depression from the last 3 decades and describes an emerging neurocircuitry model of mood disorders, focusing on critical circuits of cognition and emotion, particularly those networks involved in the regulation of evaluative, expressive and experiential aspects of emotion. The relevance of this model for neurotherapeutics is discussed, as well as the role of functional neuroimaging of psychiatric disorders.

Are emotions associated with activity during rest or interoception? An exploratory fMRI study in healthy subjects

Imaging studies investigating the default-mode network (DMN) of the brain revealed the phenomenon of elevated neural responses during periods of rest. This effect has been shown to be abnormally elevated in regions of the DMN concerning mood disorders like major depressive disorder (MDD). Since these disorders are accompanied by impaired emotional functioning, this leads to the suggestion of an association between activity during rest conditions and emotions, which remains to be demonstrated in a healthy and clinical population. Controlling for interoceptive processing, a process often closely connected to emotional functioning, we here demonstrate in an fMRI study of 30 healthy subjects the connection between activity during rest conditions in regions of the DMN and emotions in a psychologically, regionally, and stimulus specific way. Our findings provide further insight into the psychological functions underlying rest activity. Our findings in healthy subjects may also have future implications for a better understanding of mood disorders.

Conscious perception of errors and its relation to the anterior insula

To detect erroneous action outcomes is necessary for flexible adjustments and therefore a prerequisite of adaptive, goal-directed behavior. While performance monitoring has been studied intensively over two decades and a vast amount of knowledge on its functional neuroanatomy has been gathered, much less is known about conscious error perception, often referred to as error awareness. Here, we review and discuss the conditions under which error awareness occurs, its neural correlates and underlying functional neuroanatomy. We focus specifically on the anterior insula, which has been shown to be (a) reliably activated during performance monitoring and (b) modulated by error awareness. Anterior insular activity appears to be closely related to autonomic responses associated with consciously perceived errors, although the causality and directions of these relationships still needs to be unraveled. We discuss the role of the anterior insula in generating versus perceiving autonomic responses and as a key player in balancing effortful task-related and resting-state activity. We suggest that errors elicit reactions highly reminiscent of an orienting response and may thus induce the autonomic arousal needed to recruit the required mental and physical resources. We discuss the role of norepinephrine activity in eliciting sufficiently strong central and autonomic nervous responses enabling the necessary adaptation as well as conscious error perception.

The insular cortex: a comparative perspective

The human insular cortex is involved in a variety of viscerosensory, visceromotor, and interoceptive functions, and plays a role in complex processes such as emotions, music, and language. Across mammals, the insula has considerable morphologic variability. We review the structure and connectivity of the insula in laboratory animals (mouse, domestic cat, macaque monkey), and we present original data on the morphology and cytoarchitecture of insular cortex in less common species including a large carnivore (the Atlantic walrus, Odobenus rosmarus), two artiodactyls (the pigmy hippopotamus, Hexaprotodon liberiensis, and the Western bongo, Tragelaphus eurycerus), two cetaceans (the beluga whale, Delphinapterus leucas, and the minke whale, Balaenoptera acutorostrata), and a sirenian (the Florida manatee, Trichechus manatus latirostris). The insula shows substantial variability in shape, extent, and gyral and sulcal patterns, as well as differences in laminar organization, cellular specialization, and structural association with the claustrum. Our observations reveal that the insular cortex is extremely variable among mammals. These differences could be related to the role exerted by specific and selective pressures on cortical structure during evolution. We conclude that it is not possible to identify a general model of organization for the mammalian insular cortex.

Role of the anterior insula in task-level control and focal attention

In humans, the anterior insula (aI) has been the topic of considerable research and ascribed a vast number of functional properties by way of neuroimaging and lesion studies. Here, we argue that the aI, at least in part, plays a role in domain-general attentional control and highlight studies (Dosenbach et al. 2006; Dosenbach et al. 2007) supporting this view. Additionally, we discuss a study (Ploran et al. 2007) that implicates aI in processes related to the capture of focal attention. Task-level control and focal attention may or may not reflect information processing supported by a single functional area (within the aI). Therefore, we apply a novel technique (Cohen et al. 2008) that utilizes resting state functional connectivity MRI (rs-fcMRI) to determine whether separable regions exist within the aI. rs-fcMRI mapping suggests that the ventral portion of the aI is distinguishable from more dorsal/anterior regions, which are themselves distinct from more posterior parts of the aI. When these regions are applied to functional MRI (fMRI) data, the ventral and dorsal/anterior regions support processes potentially related to both task-level control and focal attention, whereas the more posterior aI regions did not. These findings suggest that there exists some functional heterogeneity within aI that may subserve related but distinct types of higher-order cognitive processing.

The role of anterior insular cortex in social emotions

Functional neuroimaging investigations in the fields of social neuroscience and neuroeconomics indicate that the anterior insular cortex (AI) is consistently involved in empathy, compassion, and interpersonal phenomena such as fairness and cooperation. These findings suggest that AI plays an important role in social emotions, hereby defined as affective states that arise when we interact with other people and that depend on the social context. After we link the role of AI in social emotions to interoceptive awareness and the representation of current global emotional states, we will present a model suggesting that AI is not only involved in representing current states, but also in predicting emotional states relevant to the self and others. This model also proposes that AI enables us to learn about emotional states as well as about the uncertainty attached to events, and implies that AI plays a dominant role in decision making in complex and uncertain environments. Our review further highlights that dorsal and ventro-central, as well as anterior and posterior subdivisions of AI potentially subserve different functions and guide different aspects of behavioral regulation. We conclude with a section summarizing different routes to understanding other people's actions, feelings and thoughts, emphasizing the notion that the predominant role of AI involves understanding others' feeling and bodily states rather than their action intentions or abstract beliefs.