Interoceptive Awareness and the Insula – Application of Neuroimaging Techniques in Psychotherapy

Interoceptive awareness is defined as the awareness of stimuli originating inside one’s own body such as the heartbeat. The emergence of new brain imaging techniques like functional magnetic resonance imaging (fMRI) or magnetic resonance spectroscopy (MRS) has increased our knowledge of neural substrates underlying interoceptive awareness. In particular, the bilateral brain structure of the insula has been identified as a key region involved in interoceptive processes in healthy populations. In line with prominent theories of human emotion, the insula has an important function in connecting interoceptive awareness with affective experience. This connection hinging on the insula between interoception and emotional processing is suggestive of an involvement of the insula in mood disorders such as major depressive disorder (MDD). Multilayered deficits in the insula cortex of depressed individuals such as abnormal function, biochemistry, and anatomy support this hypothesis. The aim of the present article is a) to describe the importance of the insula for the interplay between interoception and emotional processing and b) how this might be figured into psychotherapeutic treatment of depressed patients using new imaging techniques like real-time fMRI. The article begins with a brief introduction about neuroanatomical settings of the insula (I. Introduction–Neuroanatomical background of the insula). Afterwards, early behavioral studies to investigate interoceptive awareness are described (II. A step Back–First attempts to investigate interoceptive awareness), followed by a description of more recent imaging studies outlining neural mechanisms underlying interoceptive awareness and emotional processing in the insula (III. The insula as key region involved in functional interoception and emotion.) Throughout, the article addresses the question of why the investigation of individuals suffering from depression might provide novel insights into the neural underpinnings of interoceptive awareness and its link to abnormal behavior (IV. Why study interoceptive awareness in depressed participants?). Following the description of a selected study that combines for the first time functional results of interoception (using fMRI) with biochemical results of the insula (using MRS) (V. Neuroimaging in interoceptive awareness combining fMRI and MRS – A specific study), the article concludes with a perspective outlining the potential for using imaging techniques like real-time fMRI to enhance neural activity in the insula during interoceptive awareness. This approach potentially leads to faster recovery in depressed patients and might be the first therapeutic application of functional imaging in psychiatry (VI. Perspectives: Neurofeedback in major depression using real-time fMRI)

Interoception in insula subregions as a possible state marker for depression - an exploratory fMRI study investigating healthy, depressed and remitted participants

Background: Interoceptive awareness (iA), the awareness of stimuli originating inside the body, plays an important role in human emotions and psychopathology. The insula is particularly involved in neural processes underlying iA. However, iA-related neural activity in the insula during the acute state of major depressive disorder (MDD) and in remission from depression has not been explored. Methods: A well-established fMRI paradigm for studying (iA; heartbeat counting) and exteroceptive awareness (eA; tone counting) was used. Study participants formed three independent groups: patients suffering from MDD, patients in remission from MDD or healthy controls. Task-induced neural activity in three functional subdivisions of the insula was compared between these groups. Results: Depressed participants showed neural hypo-responses during iA in anterior insula regions, as compared to both healthy and remitted participants. The right dorsal anterior insula showed the strongest response to iA across all participant groups. In depressed participants there was no differentiation between different stimuli types in this region (i.e., between iA, eA and noTask). Healthy and remitted participants in contrast showed clear activity differences. Conclusions: This is the first study comparing iA and eA-related activity in the insula in depressed participants to that in healthy and remitted individuals. The preliminary results suggest that these groups differ in there being hypo- responses across insula regions in the depressed participants, whilst non- psychiatric participants and patients in remission from MDD show the same neural activity during iA in insula subregions implying a possible state marker for MDD. The lack of activity differences between different stimulus types in the depressed group may account for their symptoms of altered external and internal focus

An interoceptive predictive coding model of conscious presence

We describe a theoretical model of the neurocognitive mechanisms underlying conscious presence and its disturbances. The model is based on interoceptive prediction error and is informed by predictive models of agency, general models of hierarchical predictive coding and dopaminergic signaling in cortex, the role of the anterior insular cortex (AIC) in interoception and emotion, and cognitive neuroscience evidence from studies of virtual reality and of psychiatric disorders of presence, specifically depersonalization/derealization disorder. The model associates presence with successful suppression by top-down predictions of informative interoceptive signals evoked by autonomic control signals and, indirectly, by visceral responses to afferent sensory signals. The model connects presence to agency by allowing that predicted interoceptive signals will depend on whether afferent sensory signals are determined, by a parallel predictive-coding mechanism, to be self-generated or externally caused. Anatomically, we identify the AIC as the likely locus of key neural comparator mechanisms. Our model integrates a broad range of previously disparate evidence, makes predictions for conjoint manipulations of agency and presence, offers a new view of emotion as interoceptive inference, and represents a step toward a mechanistic account of a fundamental phenomenological property of consciousness

Sensory processing in autism across exteroceptive and interoceptive domains

Objective: The current article discusses recent literature on perceptual processing in autism and aims to provide a critical review of existing theories of autistic perception and suggestions for future work. Method: We review findings detailing exteroceptive and interoceptive processing in autism and discuss their neurobiological basis as well as potential links and analogies between sensory domains. Results: Many atypicalities of autistic perception described in the literature can be explained either by weak neural synchronization or by atypical perceptual inference. Evidence for both mechanisms is found across the different sensory domains considered in this review. Conclusions: We argue that weak neural synchronization and atypical perceptual inference might be complementary neural mechanisms that describe the complex bottom-up and top-down differences of autistic perception, respectively. Future work should be sensitive to individual differences to determine if divergent patterns of sensory processing are observed within individuals, rather than looking for global changes at a group level. Determining whether divergent patterns of exteroceptive and interoceptive sensory processing may contribute to prototypical social and cognitive characteristics of autism may drive new directions in our conceptualization of autis

Sensory processing in autism across exteroceptive and interoceptive domains

Objective: The current article discusses recent literature on perceptual processing in autism and aims to provide a critical review of existing theories of autistic perception and suggestions for future work. Method: We review findings detailing exteroceptive and interoceptive processing in autism and discuss their neurobiological basis as well as potential links and analogies between sensory domains. Results: Many atypicalities of autistic perception described in the literature can be explained either by weak neural synchronization or by atypical perceptual inference. Evidence for both mechanisms is found across the different sensory domains considered in this review. Conclusions: We argue that weak neural synchronization and atypical perceptual inference might be complementary neural mechanisms that describe the complex bottom-up and top-down differences of autistic perception, respectively. Future work should be sensitive to individual differences to determine if divergent patterns of sensory processing are observed within individuals, rather than looking for global changes at a group level. Determining whether divergent patterns of exteroceptive and interoceptive sensory processing may contribute to prototypical social and cognitive characteristics of autism may drive new directions in our conceptualization of autism

Etiology, triggers and neurochemical circuits associated with unexpected, expected, and laboratory-induced panic attacks

Panic disorder (PD) is a severe anxiety disorder that is characterized by recurrent panic attacks (PA), which can be unexpected (uPA, i.e., no clear identifiable trigger) or expected (ePA). Panic typically involves an abrupt feeling of catastrophic fear or distress accompanied by physiological symptoms such as palpitations, racing heart, thermal sensations, and sweating. Recurrent uPA and ePA can also lead to agoraphobia, where subjects with PD avoid situations that were associated with PA. Here we will review recent developments in our understanding of PD, which includes discussions on: symptoms and signs associated with uPA and ePAs; Diagnosis of PD and the new DSM-V; biological etiology such as heritability and gene×environment and gene×hormonal development interactions; comparisons between laboratory and naturally occurring uPAs and ePAs; neurochemical systems that are associated with clinical PAs (e.g. gene associations; targets for triggering or treating PAs), adaptive fear and panic response concepts in the context of new NIH RDoc approach; and finally strengths and weaknesses of translational animal models of adaptive and pathological panic states

Primary interoceptive cortex activity during simulated experiences of the body

Studies of the classic exteroceptive sensory systems (e.g., vision, touch) consistently demonstrate that vividly imagining a sensory experience of the world – simulating it – is associated with increased activity in the corresponding primary sensory cortex. We hypothesized, analogously, that simulating internal bodily sensations would be associated with increased neural activity in primary interoceptive cortex. An immersive, language-based mental imagery paradigm was used to test this hypothesis (e.g., imagine your heart pounding during a roller coaster ride, your face drenched in sweat during a workout). During two neuroimaging experiments, participants listened to vividly described situations and imagined “being there” in each scenario. In Study 1, we observed significantly heightened activity in primary interoceptive cortex (of dorsal posterior insula) during imagined experiences involving vivid internal sensations. This effect was specific to interoceptive simulation: it was not observed during a separate affect focus condition in Study 1, nor during an independent Study 2 that did not involve detailed simulation of internal sensations (instead involving simulation of other sensory experiences). These findings underscore the large-scale predictive architecture of the brain and reveal that words can be powerful drivers of bodily experiences

Extrinsic and default mode networks in psychiatric conditions: Relationship to excitatory-inhibitory transmitter balance and early trauma.

Over the last three decades there has been an accumulation of Magnetic Resonance Imaging (MRI) studies reporting that aberrant functional networks may underlie cognitive deficits and other symptoms across a range of psychiatric diagnoses. The use of pharmacological MRI and H-1-Magnetic Resonance Spectroscopy (H-1-MRS) has allowed researchers to investigate how changes in network dynamics are related to perturbed excitatory and inhibitory neurotransmission in individuals with psychiatric conditions. More recently, changes in functional network dynamics and excitatory/inhibitory (E/I) neurotransmission have been linked to early childhood trauma, a major antecedents for psychiatric illness in adulthood. Here we review studies investigating whether perturbed network dynamics seen across psychiatric conditions are related to changes in E/I neurotransmission, and whether such changes could be linked to childhood trauma. Whilst there is currently a paucity of studies relating early traumatic experiences to altered E/I balance and network function, the research discussed here lead towards a plausible mechanistic hypothesis, linking early traumatic experiences to cognitive dysfunction and symptoms mediated by E/I neurotransmitter imbalances