Neuroanatomical basis for first- and second-order representations of bodily states

The neurobiology of interoception and affect

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

Decoding fMRI data with support vector machines and deep neural networks

BACKGROUND

Multivoxel pattern analysis (MVPA) examines fMRI activation patterns associated with different cognitive conditions. Support vector machines (SVMs) are the predominant method in MVPA. While SVM is intuitive and easy to apply, it is mainly suitable for analyzing data that are linearly separable. Convolutional neural networks (CNNs) are known to have the ability to approximate nonlinear relationships. Applications of CNN to fMRI data are beginning to appear with increasing frequency, but our understanding of the similarities and differences between CNN models and SVM models is limited.

NEW METHOD

We compared the two methods when they are applied to the same datasets. Two datasets were considered: (1) fMRI data collected from participants during a cued visual spatial attention task and (2) fMRI data collected from participants viewing natural images containing varying degrees of affective content.

RESULTS

We found that (1) both SVM and CNN are able to achieve above-chance decoding accuracies for attention control and emotion processing in both the primary visual cortex and the whole brain, (2) the CNN decoding accuracies are consistently higher than that of the SVM, (3) the SVM and CNN decoding accuracies are generally not correlated, and (4) the heatmaps derived from SVM and CNN are not significantly overlapping.

COMPARISON WITH EXISTING METHODS

By comparing SVM and CNN we pointed out the similarities and differences between the two methods.

CONCLUSIONS

SVM and CNN rely on different neural features for classification. Applying both to the same data may yield a more comprehensive understanding of neuroimaging data.

Bidirectional relationship between insular grey matter volume and alexithymia: Evidence from a longitudinal study

BACKGROUND

The insula is considered to be involved in emotional cognitive processes, and may be structurally altered in people with alexithymia. However, it remains unclear how the relationship between the insula and alexithymia changes over time. This study aimed to investigate whether alexithymia has longitudinal relationship with the insular structure.

METHODS

Having processed structural MRI data via FreeSurfer, the insula was divided into five sub-regions, and the Toronto Alexithymia Scale was administered to assess alexithymia in the general population. Subsequently, we established the latent change score models between insular sub-regions and the alexithymia (N = 252).

RESULTS

The TAS-20 mean value of the sample at Time 1 was not significantly different by sex (t = -0.993, df = 250, p = 0.321), while the TAS-20 mean value at Time 2 was slightly different by sex (t = 2.025, df = 250, p = 0.044). Most insular grey matter volumes at Time 1 and Time 2 were significantly associated with TAS-20 at Time 2. The baseline alexithymia and insular grey matter volume positively predicted the other's rate of change between Time 1 and Time 2 in a bidirectional way.

LIMITATIONS

This study had a limited number of measurement time points, potential bias due to smaller sample sizes and gender imbalance, as well as the potential for inaccuracy in the self-report measure of alexithymia.

CONCLUSIONS

Time-lagged alexithymia changes and insular grey matter volume changes occur in coupled manner over time, which might improve our understanding of the neurological underpinnings of alexithymia, and shed light on clinical and psychological treatment for alexithymia.

Acute right insular ischaemic lesions and poststroke left ventricular dysfunction

INTRODUCTION

Myocardial injury related to acute ischaemic stroke is common even without primary cardiac disease. We intended to determine associations between values of left ventricular ejection fraction (LVEF) and ischaemic stroke lesion sites.

METHODS

Of a local database, patients with acute first-ever ischaemic stroke confirmed by brain imaging but without pre-existing heart disease were included. The cardiac morphology and LVEF were obtained from transthoracic or transesophageal echocardiography, and impaired LVEF was categorised as mild (35%-50%), moderate (34%-25%) and severe (<25%). Patient age, stroke severity, ischaemic lesion volume, prevalence of troponin I increase (>0.1 ng/mL), atrial fibrillation and cardiac wall motion abnormalities were assessed and compared between patients with and without impaired LVEF after stroke (significance: p<0.05). A multivariate voxelwise lesion analysis correlated LVEF after stroke with sites of ischaemic lesions.

RESULTS

Of 1209 patients who had a stroke, 231 (mean age 66.3±14.0 years) met the inclusion criteria; 40 patients (17.3%) had an impaired LVEF after stroke. Patients with impaired LVEF had higher infarct volumes (53.8 mL vs 30.0 mL, p=0.042), a higher prevalence of troponin increase (17.5% vs 4.2%, p=0.006), cardiac wall motion abnormalities (42.5% vs 5.2%, p<0.001) and atrial fibrillation (60.0% vs 26.2%, p<0.001) than patients with LVEF of >50%. The multivariate voxelwise lesion analysis yielded associations between decreased LVEF and damaged voxels in the insula, amygdala and operculum of the right hemisphere.

CONCLUSION

Our imaging analysis unveils a prominent role of the right hemispheric central autonomic network, especially of the insular cortex, in the brain-heart axis. Our results support preliminary evidence that acute ischaemic stroke in distinct brain regions of the central autonomic network may directly impair cardiac function and thus further supports the concept of a distinct stroke-heart syndrome.

Combining the Inner Self with the Map of the Body: Evidence for White Matter Contribution to the Relation Between Interoceptive Sensibility and Nonaction-oriented Body Representation

Very recent studies on healthy individuals suggest that changes in the sensibility toward internal bodily sensations across the lifespan affect the ability to mentally represent one's body, in terms of action-oriented and nonaction-oriented body representation (BR). Little is known about the neural correlates of this relation. Here we fill this gap using the neuropsychological model provided by focal brain damage. Sixty-five patients with unilateral stroke (20 with left and 45 with right brain damage, LBD and RBD, respectively) participated in this study. Both action-oriented BR and nonaction-oriented BR were tested; interoceptive sensibility was assessed as well. First, we tested whether interoceptive sensibility predicted action-oriented BR and nonaction-oriented BR, in RBD and LBD separately. Then, a track-wise hodological lesion-deficit analysis was performed in a subsample of twenty-four patients to test the brain network supporting this relation. We found that interoceptive sensibility predicted the performances in the task tapping nonaction-oriented BR. The higher interoceptive sensibility was, the worse patients performed. This relation was associated with the disconnection probability of the corticospinal tract, the fronto-insular tract, and the pons. We expand over the previous findings on healthy individuals, supporting the idea that high levels of interoceptive sensibility negatively affect BR. Specific frontal projections and frontal u-shaped tracts may play a pivotal role in such an effect, likely affecting the development of a first-order representation of the self within the brainstem autoregulatory centers and posterior insula and of a second-order representation of the self within the anterior insula and higher-order prefrontal areas.

Parieto-occipital ERP indicators of gut mechanosensation in humans

Understanding the neural processes governing the human gut-brain connection has been challenging due to the inaccessibility of the body's interior. Here, we investigated neural responses to gastrointestinal sensation using a minimally invasive mechanosensory probe by quantifying brain, stomach, and perceptual responses following the ingestion of a vibrating capsule. Participants successfully perceived capsule stimulation under two vibration conditions (normal and enhanced), as evidenced by above chance accuracy scores. Perceptual accuracy improved significantly during the enhanced relative to normal stimulation, which was associated with faster stimulation detection and reduced reaction time variability. Capsule stimulation induced late neural responses in parieto-occipital electrodes near the midline. Moreover, these 'gastric evoked potentials' showed intensity-dependent increases in amplitude and were significantly correlated with perceptual accuracy. Our results replicated in a separate experiment, and abdominal X-ray imaging localized most capsule stimulations to the gastroduodenal segments. Combined with our prior observation that a Bayesian model is capable of estimating computational parameters of gut-brain mechanosensation, these findings highlight a unique form of enterically-focused sensory monitoring within the human brain, with implications for understanding gut feelings and gut-brain interactions in healthy and clinical populations.

Decoding fMRI Data: A Comparison Between Support Vector Machines and Deep Neural Networks

Multivoxel pattern analysis (MVPA) examines the differences in fMRI activation patterns associated with different cognitive conditions and provides information not possible with the conventional univariate analysis. Support vector machines (SVMs) are the predominant machine learning method in MVPA. SVMs are intuitive and easy to apply. The limitation is that it is a linear method and mainly suitable for analyzing data that are linearly separable. Convolutional neural networks (CNNs), a class of AI models originally developed for object recognition, are known to have the ability to approximate nonlinear relationships. CNNs are rapidly becoming an alternative to SVMs. The purpose of this study is to compare the two methods when they are applied to the same datasets. Two datasets were considered: (1) fMRI data collected from participants during a cued visual spatial attention task (the attention dataset) and (2) fMRI data collected from participants viewing natural images containing varying degrees of affective content (the emotion dataset). We found that (1) both SVM and CNN are able to achieve above chance level decoding accuracies for attention control and emotion processing in both the primary visual cortex and the whole brain with, (2) the CNN decoding accuracies are consistently higher than that of the SVM, (3) the SVM and CNN decoding accuracies are generally not correlated with each other, and (4) the heatmaps derived from SVM and CNN are not significantly overlapping. These results suggest that (1) there are both linearly separable features and nonlinearly separable features in fMRI data that distinguish cognitive conditions and (2) applying both SVM and CNN to the same data may yield a more comprehensive understanding of neuroimaging data.

Key points

We compared the performance and characteristics of SVM and CNN, two major methods in MVPA analysis of neuroimaging data, by applying them to the same two fMRI datasets.Both SVM and CNN achieved decoding accuracies above chance level for both datasets in the chosen ROIs and the CNN decoding accuracies were consistently higher than those of SVM.The heatmaps derived from SVM and CNN, which assess the contribution of voxels or brain regions to MVPA decoding performance, showed no significant overlap, providing evidence that the two methods depend on distinct brain activity patterns for decoding cognitive conditions.

Sex differences in functional brain networks involved in interoception: An fMRI study

Interoception can be described as the ability to perceive inner body sensations and it is different between biological sex. However, no previous research correlated this ability with brain functional connectivity (FC) between males and females. In this study, we used resting-state functional magnetic resonance imaging to investigate FC of networks involved in interoception among males and females in a sample of healthy volunteers matched for age. In total, 67 participants (34 females, mean age 44.2; 33 males, mean age 37.2) underwent a functional MRI session and completed the Self-Awareness Questionnaire (SAQ) that tests the interoceptive awareness. To assess the effect of sex on scores obtained on the SAQ we performed a multivariate analysis of variance. A whole-brain seed-to-seed FC analysis was conducted to investigate the correlation between SAQ score and FC, and then to test differences in FC between males and females with SAQ score as a covariate. MANOVA revealed a significant difference in SAQ scores between males and females with higher values for the second ones. Also, significant correlations among interoception scores and FC in Salience network and fronto-temporo-parietal brain areas have been detected, with a sharp prevalence for the female. These results support the idea of a female advantage in the attention toward interoceptive sensations, suggesting common inter-network areas that concur to create the sense of self.

Sleep Loss Influences the Interconnected Brain-Body Regulation of Cardiovascular Function in Humans

OBJECTIVE

Poor sleep is associated with hypertension, a major risk factor for cardiovascular disease. However, the mechanism(s) through which sleep loss affects cardiovascular health remains largely unknown, including the brain and body systems that regulate vascular function.

METHODS

Sixty-six healthy adults participated in a repeated-measures, crossover, experimental study involving assessments of cardiovascular function and brain connectivity after a night of sleep and a night of sleep deprivation.

RESULTS

First, sleep deprivation significantly increased blood pressure-both systolic and diastolic. Interestingly, this change was independent of any increase in heart rate, inferring a vasculature-specific rather than direct cardiac pathway. Second, sleep loss compromised functional brain connectivity within the vascular control network, specifically the insula, anterior cingulate, amygdala, and ventral and medial prefrontal cortices. Third, sleep loss-related changes in brain connectivity and vascular tone were not independent, but significantly interdependent, with changes within the vascular control brain network predicting the sleep-loss shift toward hypertension.

CONCLUSIONS

These findings establish an embodied framework in which sleep loss confers increased risk of cardiovascular disease through an impact upon central brain control of vascular tone, rather than a direct impact on accelerated heart rate itself.

Functional anatomy of the vagus system: How does the polyvagal theory comply?

Due to its pivotal role in autonomic networks and interoception, the vagus attracts continued interest from both basic scientists and therapists of various clinical disciplines. In particular, the widespread use of heart rate variability as an index of autonomic cardiac control and a proposed central role of the vagus in biopsychological concepts, e.g., the polyvagal theory, provide a good opportunity to recall basic features of vagal anatomy. In addition to the "classical" vagal brainstem nuclei, i.e., dorsal motor nucleus, nucleus ambiguus and nucleus tractus solitarii, the spinal trigeminal and paratrigeminal nuclei come into play as targets of vagal afferents. On the other hand, the nucleus of the solitary tract receives and integrates not only visceral but also somatic afferents.

Going beyond the DSM in predicting, diagnosing, and treating autism spectrum disorder with covarying alexithymia and OCD: A structural equation model and process-based predictive coding account

Background

There is much overlap among the symptomology of autistic spectrum disorders (ASDs), obsessive compulsive disorders (OCDs), and alexithymia, which all typically involve impaired social interactions, repetitive impulsive behaviors, problems with communication, and mental health.

Aim

This study aimed to identify direct and indirect associations among alexithymia, OCD, cardiac interoception, psychological inflexibility, and self-as-context, with the DV ASD and depression, while controlling for vagal related aging.

Methodology

The data involved electrocardiogram (ECG) heart rate variability (HRV) and questionnaire data. In total, 1,089 participant's data of ECG recordings of healthy resting state HRV were recorded and grouped into age categories. In addition to this, another 224 participants completed an online survey that included the following questionnaires: Yale-Brown Obsessive Compulsive Scale (Y-BOCS); Toronto Alexithymia Scale 20 (TAS-20); Acceptance and Action Questionnaire (AAQII); Depression, Anxiety, and Stress Scale 21 (DAS21); Multi-dimensional Assessment of Interoceptive Awareness Scale (MAIA); and the Self-as-Context Scale (SAC).

Results

Heart rate variability was shown to decrease with age when controlling for BMI and gender. In the two SEMs produced, it was found that OCD and alexithymia were causally associated with autism and depression indirectly through psychological inflexibility, SAC, and ISen interoception.

Conclusion

The results are discussed in relation to the limitations of the DSM with its categorical focus of protocols for syndromes and provide support for more flexible ideographic approaches in diagnosing and treating mental health and autism within the Extended Evolutionary Meta-Model (EEMM). Graph theory approaches are discussed in their capacity to depict the processes of change potentially even at the level of the relational frame.

The Constructionist Approach to Emotional Aging: Theoretical Insights and Predictions

In this article, we introduce a constructionist approach to understanding emotional aging in adulthood. The purpose of the paper is to show how constructionism offers a promising avenue for gaining new insights into age-related changes in emotional experiences. We begin by introducing the constructionist theoretical framework and illustrating how constructionism may shape conceptualizations of emotional aging in adulthood. We compare the constructionist conceptualization of emotional aging with existing conceptualizations of emotional aging derived from prominent theories of emotional aging, focusing on how such conceptualizations highlight different aspects of emotional aging (e.g., different mechanisms) and overlook or downplay other aspects. We conclude by explicating what constructionism may offer research on emotional aging, including considerations of research agendas, study designs, and method of measurement.

Migraine, Brain Glucose Metabolism and the "Neuroenergetic" Hypothesis: A Scoping Review

Increasing evidence suggests that migraine may be the result of an impaired brain glucose metabolism. Several studies have reported brain mitochondrial dysfunction, impaired brain glucose metabolism and gray matter volume reduction in specific brain areas of migraineurs. Furthermore, peripheral insulin resistance, a condition demonstrated in several studies, may extend to the brain, leading to brain insulin resistance. This condition has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis, mainly during high metabolic demand. This scoping review examines the clinical, epidemiologic and pathophysiologic data supporting the hypothesis that abnormalities in brain glucose metabolism may generate a mismatch between the brain's energy reserve and metabolic expenditure, triggering migraine attacks. Moreover, alteration in glucose homeostasis could generate a chronic brain energy deficit promoting migraine chronification. Lastly, insulin resistance may link migraine with its comorbidities, like obesity, depression, cognitive impairment and cerebrovascular diseases. PERSPECTIVE: Although additional experimental studies are needed to support this novel "neuroenergetic" hypothesis, brain insulin resistance in migraineurs may unravel the pathophysiological mechanisms of the disease, explaining the migraine chronification and connecting migraine with comorbidities. Therefore, this hypothesis could elucidate novel potential approaches for migraine treatment.

Cardiac deceleration following positive and negative feedback is influenced by competence-based social status

Previous studies indicate that neurophysiological signatures of feedback processing might be enhanced when participants are assigned a low-status position. Error commission and negative feedback can evoke responses in the peripheral (autonomic) nervous system including heart rate deceleration. We conducted an exploratory study to investigate whether such activity can be modulated by the participant's social status in a competence-based hierarchy. Participants were engaged in a cooperative time estimation task with two same-gender confederates. On each trial, they were provided with positive or negative feedback depending on their time estimation performance. Their social status varied during the task, so that they were either at the top (high-status) or at the bottom (low-status) of the hierarchy in different blocks. Results showed that cardiac deceleration was significantly modulated by feedback valence in the high-status but not in the low-status condition. We interpret this result as an increased activation of the performance monitoring system elicited by the desire to maintain a high-status position in an unstable hierarchy. In this vein, negative feedback might be processed as an aversive stimulus that signals a threat to the acquired status.

Mindfulness-Based Interventions for the Treatment of Aberrant Interoceptive Processing in Substance Use Disorders

Altered interoception, or the processing of bodily signals, has been argued to play a role in the development and maintenance of substance use disorders (SUD). Therefore, interoceptive interventions focusing on bodily awareness, such as mindfulness meditation, may improve treatment outcomes for individuals with SUD. Here we review: (1) subjective, behavioral and brain evidence for altered interoceptive processing in SUD, focusing on insular and anterior cingulate cortices (INS, ACC), key regions for interoceptive processing; (2) research highlighting links between mindfulness and brain function; and (3) extant brain research investigating mindfulness-based interventions in SUD. SUD tend to be characterized by heightened INS and ACC responses to drug cues but blunted interoceptive awareness and attenuated INS and ACC responses during tasks involving bodily attention and/or perturbations. In contrast, mindfulness interventions in healthy individuals are linked to enhanced INS and ACC responses and heightened interoceptive awareness. It is crucial for future research to identify: (1) whether mindfulness-based treatments are efficacious across substance classes; (2) what particular approaches and dosages show the largest effect sizes in enhancing INS and ACC function to non-drug stimuli and reducing responsivity to substance cues, thereby improving SUD treatment outcomes (reducing drug craving and relapse).

Insular Dichotomy in the Implicit Detection of Emotions in Human Faces

The functional roles of the insula diverge between its posterior portion (PI), mainly connected with somato-sensory and motor areas, and its anterior section (AI) connected with the frontal, limbic, and cingulate regions. We report intracranial recordings of local field evoked potentials from PI, AI, and the visual fusiform gyrus to a full array of emotional faces including pain while the individuals' attention was diverted from emotions. The fusiform gyrus and PI responded equally to all types of faces, including neutrals. Conversely, the AI responded only to emotional faces, maximally to pain and fear, while remaining insensitive to neutrals. The two insular sectors reacted with almost identical latency suggesting their parallel initial activation via distinct functional routes. The consistent responses to all emotions, together with the absence of response to neutral faces, suggest that early responses in the AI reflect the immediate arousal value and behavioral relevance of emotional stimuli, which may be subserved by "fast track" routes conveying coarse-spatial-frequency information via the superior colliculus and dorsal pulvinar. Such responses precede the conscious detection of the stimulus' precise signification and valence, which need network interaction and information exchange with other brain areas, for which the AI is an essentialhub.

Brain 5-HT2A receptor binding and its neural network related to behavioral inhibition system

The tendency to avoid punishment, called behavioral inhibition system, is an essential aspect of motivational behavior. Behavioral inhibition system is related to negative affect, such as anxiety, depression and pain, but its neural basis has not yet been clarified. To clarify the association between individual variations in behavioral inhibition system and brain 5-HT_2A receptor availability and specify which brain networks were involved in healthy male subjects, using [¹⁸F]altanserin positron emission tomography and resting-state functional magnetic resonance imaging. Behavioral inhibition system score negatively correlated with 5-HT_2A receptor availability in anterior cingulate cortex. A statistical model indicated that the behavioral inhibition system score was associated with 5-HT_2A receptor availability, which was mediated by the functional connectivity between anterior cingulate cortex and left middle frontal gyrus, both of which involved in the cognitive control of negative information processing. Individuals with high behavioral inhibition system displays low 5-HT_2A receptor availability in anterior cingulate cortex and this cognitive control network links with prefrontal-cingulate integrity. These findings have implications for underlying the serotonergic basis of physiologies in aversion.

Sympathetic Neural Control in Humans with Anxiety-Related Disorders

Numerous conceptual models are used to describe the dynamic responsiveness of physiological systems to environmental pressures, originating with Claude Bernard's milieu intérieur and extending to more recent models such as allostasis. The impact of stress and anxiety upon these regulatory processes has both basic science and clinical relevance, extending from the pioneering work of Hans Selye who advanced the concept that stress can significantly impact physiological health and function. Of particular interest within the current article, anxiety is independently associated with cardiovascular risk, yet mechanisms underlying these associations remain equivocal. This link between anxiety and cardiovascular risk is relevant given the high prevalence of anxiety in the general population, as well as its early age of onset. Chronically anxious populations, such as those with anxiety disorders (i.e., generalized anxiety disorder, panic disorder, specific phobias, etc.) offer a human model that interrogates the deleterious effects that chronic stress and allostatic load can have on the nervous system and cardiovascular function. Further, while many of these disorders do not appear to exhibit baseline alterations in sympathetic neural activity, reactivity to mental stress offers insights into applicable, real-world scenarios in which heightened sympathetic reactivity may predispose those individuals to elevated cardiovascular risk. This article also assesses behavioral and lifestyle modifications that have been shown to concurrently improve anxiety symptoms, as well as sympathetic control. Lastly, future directions of research will be discussed, with a focus on better integration of psychological factors within physiological studies examining anxiety and neural cardiovascular health. © 2022 American Physiological Society. Compr Physiol 12:1-33, 2022.

Sympathetic involvement in time-constrained sequential foraging

Appraising sequential offers relative to an unknown future opportunity and a time cost requires an optimization policy that draws on a learned estimate of an environment’s richness. Converging evidence points to a learning asymmetry, whereby estimates of this richness update with a bias toward integrating positive information. We replicate this bias in a sequential foraging (prey selection) task and probe associated activation within the sympathetic branch of the autonomic system, using trial-by-trial measures of simultaneously recorded cardiac autonomic physiology. We reveal a unique adaptive role for the sympathetic branch in learning. It was specifically associated with adaptation to a deteriorating environment: it correlated with both the rate of negative information integration in belief estimates and downward changes in moment-to-moment environmental richness, and was predictive of optimal performance on the task. The findings are consistent with a framework whereby autonomic function supports the learning demands of prey selection.

Electroencephalography (EEG) Reveals Increased Frontal Activity in Social Presence

It remains an unsolved conundrum how social presence affects the neural processes involved in adaptive situation-specific decision-making mechanisms. To investigate this question, brain potential changes via electroencephalography (EEG) and skin conductance responses (SCR) were taken within this study, while participants were exposed to pre-rated pleasant, neutral, and unpleasant pictures, which they had to rate in terms of their perceived arousal. Crucially, they had to—in respective runs—do this alone and in the presence of a significant other. Contrasting respective event-related potentials (ERPs) revealed significantly more negative going potentials peaking at 708 ms post stimulus onset at mid-frontal electrode locations (around FPz and AFz), when participants were exposed to neutral pictures while in the presence of a significant other. SCR results demonstrate higher states of arousal in the presence of a significant other regardless of picture emotion category. Self-reported arousal turned out to be highest in response to neutral pictures within the significant other condition, whereas in the alone condition in response to the pleasant pictures. In light of existing literature on social aspects and the anterior cingulate cortex (ACC), the ERP finding in the significant other condition, while rating emotionally neutral pictures, is interpreted as reflecting heightened ACC activation, which is supported by electrode locations showing significant brain activity differences as well as by source localization results. Neutral pictures are inherently ambiguous, and the current results indicate the presence of another person to change the way one processes, perceives, and acts on them. This is in support for theories proposing the ACC to be part of a larger signal-specification network that gauges relevant stimuli for adequate execution of control.

Understanding heterosexual women's erotic flexibility: the role of attention in sexual evaluations and neural responses to sexual stimuli

Many women experience desires, arousal and behavior that run counter to their sexual orientation (orientation inconsistent, 'OI'). Are such OI sexual experiences cognitively and neurobiologically distinct from those that are consistent with one's sexual orientation (orientation consistent, 'OC')? To address this question, we employed a mindful attention intervention-aimed at reducing judgment and enhancing somatosensory attention-to examine the underlying attentional and neurobiological processes of OC and OI sexual stimuli among predominantly heterosexual women. Women exhibited greater neural activity in response to OC, compared to OI, sexual stimuli in regions associated with implicit visual processing, volitional appraisal and attention. In contrast, women exhibited greater neural activity to OI, relative to OC, sexual stimuli in regions associated with complex visual processing and attentional shifting. Mindfully attending to OC sexual stimuli reduced distraction, amplified women's evaluations of OC stimuli as sexually arousing and deactivated the superior cerebellum. In contrast, mindfully attending to OI sexual stimuli amplified distraction, decreased women's evaluations of OI stimuli as sexually arousing and augmented parietal and temporo-occipital activity. Results of the current study constrain hypotheses of female erotic flexibility, suggesting that sexual orientation may be maintained by differences in attentional processing that cannot be voluntarily altered.

Cardiovascular pathophysiology from the cardioneural perspective and its clinical applications

Coronary heart disease and psychological stress factors such as depression are prevalent and associated with high morbidity/mortality; they are also challenging to manage, especially when treated in isolation of each other. Recent advances support an integrated approach to their management that is built on a foundation of an extensive, multi-component network of neurological structures. In this review, we describe this extensive cardioneural network that encompasses the heart, brain, spinal cord, and ganglia throughout the body, and then discuss ambulatory and laboratory-based non-invasive measures of this network that both measure psychological stress and heart disease severity. Lastly, we discuss their potential transformative clinical and public health applications, and also possible cardioneural interventions such as exercise and biofeedback.

Neural Evidence of Mirror Self-Recognition in the Secondary Somatosensory Cortex of Macaque: Observations from a Single-Cell Recording Experiment and Implications for Consciousness

Despite mirror self-recognition being regarded as a classical indication of self-awareness, little is known about its neural underpinnings. An increasing body of evidence pointing to a role of multimodal somatosensory neurons in self-recognition guided our investigation toward the secondary somatosensory cortex (SII), as we observed single-neuron activity from a macaque monkey sitting in front of a mirror. The monkey was previously habituated to the mirror, successfully acquiring the ability of mirror self-recognition. While the monkey underwent visual and somatosensory stimulation, multimodal visual and somatosensory activity was detected in the SII, with neurons found to respond to stimuli seen through the mirror. Responses were also modulated by self-related or non-self-related stimuli. These observations corroborate that vision is an important aspect of SII activity, with electrophysiological evidence of mirror self-recognition at the neuronal level, even when such an ability is not innate. We also show that the SII may be involved in distinguishing self and non-self. Together, these results point to the involvement of the SII in the establishment of bodily self-consciousness.

Unconscious processing of emotions and the right hemisphere

Many influential authors maintain that, even if emotions are conscious experiences, the processing of information that produces emotions is usually unconscious. This chapter discusses the nonconscious aspects of emotional processing and the critical role played in them by the right hemisphere. This chapter first reviews the studies that have demonstrated the existence of unconscious or subconscious forms of emotional processing and then discusses the data supporting the hypothesis that the right hemisphere is dominant for the processing of emotions. After these topics are reviewed, the chapter will discuss investigations that have shown that the right and left amygdala have different roles in the processing of emotional stimuli, the former being involved in nonconscious and the latter in conscious forms of emotional learning. This chapter will also address the distinction proposed by Freud between "removed" and "nonremoved" forms of unconscious processing and will consider whether "nonremoved preverbal implicit memories" have a preferential link with the right hemisphere. The possibility that the right hemisphere may play a critical role not only in the formation of nonremoved subconscious memories but also in the development of denial phenomena, resulting from dynamic processes of unconscious repression, will also be discussed.

Behavioral and neurophysiological signatures of interoceptive enhancements following vagus nerve stimulation

An accruing body of research has shown that interoception (the sensing of signals from the body's internal milieu) relies on both a direct route (afforded by the vagus nerve) and a secondary route (supported by somatosensory mechanisms). However, no study has causally tested the differential role of these pathways, let alone via direct stimulation. To bridge this gap, we tested whether multidimensional signatures of interoception are modulated by noninvasive vagus nerve stimulation (nVNS). Sixty‐three participants were divided into an nVNS and a sham‐stimulation group. Before and after stimulation, both groups performed a validated heartbeat detection (HBD) task including a genuinely interoceptive condition (monitoring one's own heartbeat) and a control exteroceptive condition (tracking an aurally presented heartbeat). Electroencephalographic signals were obtained during both conditions to examine modulations of the heartbeat‐evoked potential (HEP). Moreover, before and after stimulation, participants were asked to complete a somatosensory heartbeat localization task. Results from the interoceptive condition revealed that, after treatment, only the nVNS group exhibited improved performance and greater HEP modulations. No behavioral differences were found for the exteroceptive control condition, which was nonetheless associated with significant HEP modulations. Finally, no between‐group differences were observed regarding the localization of the heartbeat sensations or relevant cardiodynamic variables (heart rate and or heart rate variability). Taken together, these results constitute unprecedented evidence that the vagus nerve plays a direct role in neurovisceral integration during interoception. This finding can constrain mechanistic models of the domain while informing a promising transdiagnostic agenda for interoceptive impairments across neuropsychiatric conditions.

Neural divergence and convergence for attention to and detection of interoceptive and somatosensory stimuli

Body awareness is constructed by signals originating from within and outside the body. How do these apparently divergent signals converge? We developed a signal detection task to study the neural convergence and divergence of interoceptive and somatosensory signals. Participants focused on either cardiac or tactile events and reported their presence or absence. Beyond some evidence of divergence, we observed a robust overlap in the pattern of activation evoked across both conditions in frontal areas including the insular cortex, as well as parietal and occipital areas, and for both attention and detection of these signals. Psycho-physiological interaction analysis revealed that right insular cortex connectivity was modulated by the conscious detection of cardiac compared to somatosensory sensations, with greater connectivity to occipito-parietal regions when attending to cardiac signals. Our findings speak in favour of the inherent convergence of bodily-related signals and move beyond the apparent antagonism between exteroception and interoception.

Individual Differences in Interoceptive Accuracy Are Correlated With Salience Network Connectivity in Older Adults

Interoceptive accuracy refers to the ability to consciously perceive the physical condition of the inner body, including one’s heartbeat. In younger adults, interoceptive accuracy is correlated with insular and orbitofrontal cortical connectivity within the salience network (SN). As interoceptive accuracy and insular cortex volume are known to decrease with aging, we aimed to evaluate the correlation between SN connectivity and interoceptive accuracy in older adults. 27 older adults (mean age, 77.29 years, SD = 6.24; 19 female) underwent resting-state functional magnetic resonance imaging, followed by a heartbeat counting task and neuropsychological test. We evaluated the correlation between interoceptive accuracy and SN connectivity with age, sex, cognitive function, and total gray matter volume as covariates. Region of interest-to-region of interest analyses showed that interoceptive accuracy was positively correlated with the functional connectivity (FC) of the left rostral prefrontal cortex with the right insular, right orbitofrontal, and anterior cingulate cortices [F(6,16) = 4.52, false discovery rate (FDR)-corrected p < 0.05]. Moreover, interoceptive accuracy was negatively correlated to the FC of the left anterior insular cortex with right intra-calcarine and visual medial cortices (F(6,16) = 2.04, FDR-corrected p < 0.10). These findings suggest that coordination between systems, with a positive correlation between left rostral prefrontal cortex and the SN and a negative correlation between left insular cortex and vision-related exteroceptive brain regions, is important for maintaining interoceptive accuracy in older adults.

Using bodily postures in the treatment of anorexia nervosa: Effects of power posing on interoception and affective states

OBJECTIVE

Power posing involves the adoption of an expansive bodily posture. This study examined whether power posing could benefit individuals with anorexia nervosa (AN) and women with normal weight in regards to interoceptive ability and affective states.

METHOD

Participants included 50 inpatients and outpatients with AN as well as 51 normal-weight women. Interoceptive accuracy (IAcc), measured by the heartbeat tracking task and interoceptive sensibility (IS), measured by confidence ratings, were assessed at baseline, after a single power posing session and after 1 week of daily training. Also, the short-term effects of power posing on subjective feelings of dominance, pleasantness, and arousal were investigated.

RESULTS

Both groups increased in their IAcc after one power posing session. Also, there was a significant main effect of time on feelings of dominance and pleasantness in the short-term. Women with AN displayed lower levels of IS, dominance, and pleasantness as well as higher levels of arousal than women without AN.

DISCUSSION

These findings suggest that power posing has the potential to increase IAcc, subjective feelings of power and pleasant affect in the short-term. Further research should investigate which mechanisms foster the effectiveness of this intervention to tailor it to the needs of women with AN.

Enhanced bodily states of fear facilitates bias perception of fearful faces

We investigated whether enhanced interoceptive bodily states of fear would facilitate recognition of the fearful faces. Participants performed an emotional judgment task after a bodily imagery task inside a functional magnetic resonance imaging scanner. In the bodily imagery task, participants were instructed to imagine feeling the bodily sensations of two specific somatotopic patterns: a fear-associated bodily sensation (FBS) or a disgust-associated bodily sensation (DBS). They were shown faces expressing various levels of fearfulness and disgust and instructed to classify the facial expression as fear or disgust. We found a stronger bias favoring the “fearful face” under the congruent FBS condition than under the incongruent DBS condition. The brain response to fearful versus intermediate faces increased in the fronto-insular-temporal network under the FBS condition, but not the DBS condition. The fearful face elicited activity in the anterior cingulate cortex and extrastriate body area under the FBS condition relative to the DBS condition. Furthermore, functional connectivity between the anterior cingulate cortex/extrastriate body area and the fronto-insular-temporal network was modulated according to the specific bodily sensation. Our findings suggest that somatotopic patterns of bodily sensation provide informative access to the collective visceral state in the fear processing via the fronto-insular-temporal network.

Common neural responses to romantic rejection and acceptance in healthy adults

Although romantic rejection and acceptance have a strong impact on mood in adults, their neural response patterns are relatively unexplored. The present study used functional magnetic resonance imaging (fMRI) to examine neural responses to romantic rejection and acceptance in 36 healthy men and women, ages 18-53 years. Activations during rejection showed extensive anatomical overlap with activations during acceptance in the ventrolateral prefrontal cortex (vlPFC) and anterior insula (AI). In an analysis of sex differences, men and women did not differ in behavioral responses; however, men showed greater activation to romantic rejection and acceptance in the left vlPFC and AI compared to women. The vlPFC and AI may play a role in social cognition, tuned to detect the intentions and feelings of others whether they are positive or negative. In the context of romantic rejection and acceptance, this activation may signal the intent of others who are desired by the individual, leading to changes in mood, self-esteem, and social motivation.

Vagus Nerve Stimulation as a Gateway to Interoception

The last two decades have seen a growing interest in the study of interoception. Interoception can be understood as a hierarchical phenomenon, referring to the body-to-brain communication of internal signals, their sensing, encoding, and representation in the brain, influence on other cognitive and affective processes, and their conscious perception. Interoceptive signals have been notoriously challenging to manipulate in experimental settings. Here, we propose that this can be achieved through electrical stimulation of the vagus nerve (either in an invasive or non-invasive fashion). The vagus nerve is the main pathway for conveying information about the internal condition of the body to the brain. Despite its intrinsic involvement in interoception, surprisingly little research in the field has used Vagus Nerve Stimulation to explicitly modulate bodily signals. Here, we review a range of cognitive, affective and clinical research using Vagus Nerve Stimulation, showing that it can be applied to the study of interoception at each level of its hierarchy. This could have considerable implications for our understanding of the interoceptive dimension of cognition and affect in both health and disease, and lead to development of new therapeutic tools.

Salience-thalamic circuit uncouples in major depressive disorder, but not in bipolar depression

BACKGROUND

Bipolar depression (BDD) and major depressive disorder (MDD) are two diseases both characterized by depressed mood and diminished interest or pleasure. Recent neuroimaging studies have implicated the thalamo-cortical circuit in mood disorders, and the present study aimed to map thalamo-cortical connectivity to explore the dissociable and common abnormalities between bipolar and major depression in this circuit.

METHOD

Applying resting-state functional magnetic resonance imaging (fMRI), we mapped the thalamo-cortical circuit using a fine-grained thalamic atlas with 8 sub-regions bilaterally in 38 BDD patients, 42 MDD patients and 39 healthy controls (HCs). Correlation analysis was then performed between thalamo-cortical connectivity and clinical variables.

RESULT

The findings showed that both patient groups exhibited prefronto-thalamo-cerebellar and sensorimotor-thalamic hypoconnectivity, while the abnormalities in MDD were more extensive. Particularly, MDD group showed decreased thalamic connectivity with the salience network including the insula, anterior cingulate cortex (ACC), and striatum. No correlations were found between the abnormal thalamo-cortical connectivity and clinical symptoms in either patient group.

LIMITATION

Most patients in our study were taking drugs at the time of scanning, which may confound our findings.

CONCLUSION

Our finding suggest that the thalamo-cortical hypofunction is a common neuro-substrate for BDD and MDD. Specifically, the hypoconnectivity between the thalamus and salience network including the insula, ACC and striatum may be a distinguished biomarker for MDD, which may help to differentiate these two emotional disorders.

Osteopathic Treatment Approach to Psychoemotional Trauma by Means of Bifocal Integration

Traumatic psychoemotional experiences often manifest in hypersympathetic states of excitement or in immobilization and withdrawal behaviors. A person with this kind of traumatic background may present with an autonomic response consistently maintained in the defensive state, which over time becomes a stressor. In this article, the authors discuss an osteopathic approach to psychoemotional trauma by means of bifocal integration, with an emphasis on promoting a relaxed body and mind by actively involving the patient in the healing process. They briefly discuss the role of mind-body therapies in treatment, considering the popular polyvagal theory and other neuropsychophysiological frameworks. The authors also focus on clinical practice, introducing the reader to the different elements of the osteopathic treatment, including the acknowledgement and integration of top-down and bottom-up dynamics in diagnosis and therapy.

Confederates in the Attic: Posttraumatic Stress Disorder, Cardiovascular Disease, and the Return of Soldier's Heart

Da Costa originally described Soldier's Heart in the 19th Century as a syndrome that occurred on the battlefield in soldiers of the American Civil War. Soldier's Heart involved symptoms similar to modern day posttraumatic stress disorder (PTSD) as well as exaggerated cardiovascular reactivity felt to be related to an abnormality of the heart. Interventions were appropriately focused on the cardiovascular system. With the advent of modern psychoanalysis, psychiatric symptoms became divorced from the body and were relegated to the unconscious. Later, the physiology of PTSD and other psychiatric disorders was conceived as solely residing in the brain. More recently, advances in psychosomatic medicine led to the recognition of mind-body relationships and the involvement of multiple physiological systems in the etiology of disorders, including stress, depression PTSD, and cardiovascular disease, has moved to the fore, and has renewed interest in the validity of the original model of the Soldier's Heart syndrome.

A multidimensional and multi-feature framework for cardiac interoception

Interoception (the sensing of inner-body signals) is a multi-faceted construct with major relevance for basic and clinical neuroscience research. However, the neurocognitive signatures of this domain (cutting across behavioral, electrophysiological, and fMRI connectivity levels) are rarely reported in convergent or systematic fashion. Additionally, various controversies in the field might reflect the caveats of standard interoceptive accuracy (IA) indexes, mainly based on heartbeat detection (HBD) tasks. Here we profit from a novel IA index (md) to provide a convergent multidimensional and multi-feature approach to cardiac interoception. We found that outcomes from our IA-md index are associated with -and predicted by- canonical markers of interoception, including the hd-EEG-derived heart-evoked potential (HEP), fMRI functional connectivity within interoceptive hubs (insular, somatosensory, and frontal networks), and socio-emotional skills. Importantly, these associations proved more robust than those involving current IA indexes. Furthermore, this pattern of results persisted when taking into consideration confounding variables (gender, age, years of education, and executive functioning). This work has relevant theoretical and clinical implications concerning the characterization of cardiac interoception and its assessment in heterogeneous samples, such as those composed of neuropsychiatric patients.

Neuroanatomy of expressive suppression: The role of the insula

Expressive suppression is a response-focused regulatory strategy aimed at concealing the outward expression of emotion that is already underway. Expressive suppression requires the integration of interoception, proprioception, and social awareness to guide behavior in alignment with personal and interpersonal goals-all processes known to involve the insular cortex. Frontotemporal dementia (FTD) provides a useful patient model for studying the insula's role in socioemotional regulation. The insula is a key target of early atrophy in FTD, causing patients to lose the ability to represent the salience of internal and external conditions and to use these representations to guide behavior. We examined a sample of 59 patients with FTD, 52 patients with Alzheimer's disease (AD), and 38 neurologically healthy controls. Subjects viewed 2 disgust-eliciting films in the laboratory. During the first film, subjects were instructed to simply watch (emotional reactivity trial); during the second, they were instructed to hide their emotions (expressive suppression trial). Structural images from a subsample of participants (n = 42; 11 FTD patients, 11 AD patients, and 20 controls) were examined in conjunction with behavior. FreeSurfer was used to quantify regional gray matter volume in 41 empirically derived neural regions in both hemispheres. Of the 3 groups studied, FTD patients showed the least expressive suppression and had the smallest insula volumes, even after controlling for age, gender, and emotional reactivity. Among the brain regions examined, the insula was the only significant predictor of expressive suppression ability, with lower insula gray matter volume in both hemispheres predicting less expressive suppression. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Effects of a mental stress challenge on brain function in coronary artery disease patients with and without depression

OBJECTIVE

Coronary artery disease (CAD) patients with comorbid depression show an increase in mortality compared to cardiac patients without depression, but the mechanisms mediating this effect remain obscure. One possible explanation for this finding is that depressed patients with CAD exhibit an increased vulnerability to stress. The purpose of this study was to assess the effects of stress and depression on brain function and to explore its relationship with myocardial ischemia in CAD patients.

METHODS

Patients with CAD and depression (N = 13) and CAD without depression (N = 15) underwent imaging of the brain with positron emission tomography and [O-15] water and imaging of the heart with single photon emission computed tomography (SPECT) and [Tc-99m] sestamibi under mental stress task and control conditions.

RESULTS

CAD patients with depression compared to nondepressed showed decreased function with mental stress in the rostral anterior cingulate, the hippocampus, parts of the dorsolateral temporal and parietal cortex, the cerebellum, and the uncus, with increased blood flow in the parahippocampus, visual association cortex, and posterior cingulate. Depressed CAD patients who became ischemic during a mental stress task had relative decreases in the caudal and posterior cingulate, orbitofrontal cortex, and cerebellum, and increased activation in the parietal cortex and precuneus/visual association cortex compared to nonischemic depressed CAD patients.

CONCLUSIONS

These findings are consistent with dysfunction in a network of brain regions involved in the stress response in patients with comorbid CAD and depression that has direct and indirect links to the heart, suggesting a pathway by which stress and depression could lead to increased risk of heart disease related morbidity and mortality. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

[Brain network dysfunctions as substrates of primary headaches]

A large body of clinical and pre-clinical evidence has shown complex interactions between bottom-up and top-down mechanisms that are essential for the discrimination of noxious information and pain perception. These endogenous systems, mainly originating from the brainstem, hypothalamus and cerebral cortex, are strongly influenced by behavioral, cognitive and emotional factors that are relevant for the survival of the individual. Under pathological conditions, however, dysfunctional engagement of these descending pathways certainly contributes to the transformation from acute into chronic pain states. In disorders such as primary headaches, dysfunctions affecting brain regulation mechanisms contribute to the generation of episodic painful states in susceptible individuals, and to the evolution from acute to chronic migraine or cluster headache. Taken together, these studies support the concept that CNS mechanisms that process trigemino-vascular pain do not consist only of a bottom-up process, whereby a painful focus modifies the inputs to the next higher level. Indeed, several CNS regions mediate subtle forms of plasticity by adjusting neural maps downstream and, consequently, altering all the modulatory mechanisms as a result of sensory, autonomic, endocrine, cognitive and emotional influences. Disturbances in normal sensory processing within these loops could lead to maladaptive changes and impaired craniofacial functions at the origin of primary headaches.

Brain Correlates of Mental Stress-Induced Myocardial Ischemia

OBJECTIVE

Coronary artery disease (CAD) is a major cause of morbidity and mortality, and despite important advances in our understanding of this disorder, the underlying mechanisms remain under investigation. Recently, increased attention has been placed on the role of behavioral factors such as emotional stress on CAD risk. Brain areas involved in memory and the stress response, including medial prefrontal cortex, insula, and parietal cortex, also have outputs to the peripheral cardiovascular system. The purpose of this study was to assess the effects of mental stress on brain and cardiac function in patients with CAD.

METHODS

CAD patients (N = 170) underwent cardiac imaging with [Tc-99m] sestamibi single-photon emission tomography at rest and during a public speaking mental stress task. On another day, they underwent imaging of the brain with [O-15] water positron emission tomography (PET) during mental stress (arithmetic and public speaking) and control conditions.

RESULTS

Patients with mental stress-induced myocardial ischemia showed increased activation with stress in anterior cingulate, inferior frontal gyrus, and parietal cortex (p < .005). This was seen with both arithmetic stress and public speaking stress. Arithmetic stress was additionally associated with left insula activation, and public speaking with right pre/postcentral gyrus and middle temporal gyrus activation (p < .005).

CONCLUSIONS

These findings suggest that mental stress-induced myocardial ischemia is associated with activation in brain areas involved in the stress response and autonomic regulation of the cardiovascular system. Altered brain reactivity to stress could possibly represent a mechanism through which stress leads to increased risk of CAD-related morbidity and mortality.

An Exploration of the Mechanism of Action of an Equine-Assisted Intervention

Though long alluded to, there is now an accumulation of evidence of the vital contribution that emotion makes to learning. Within this broad advance in understanding is a growing body of research emphasising the embodied nature of this emotion-based learning. The study presented here is a pilot study using a mixed-method approach (combining both physiological and experiential methodologies) to give a picture of the "emotional landscape" of people's learning through the intervention under study. This has allowed researchers to examine mediating pathways that may underlie any effects of an equine-assisted intervention. This study specifically focuses on examining the role of emotion. The intervention under study was used with young people with chronic mental health and behavioural problems for whom talk-based interventions were not working. Nine healthy participants aged 18-24 undertook the equine intervention, with an initial group having emotion-related psycho-physiological changes (skin conductance responses) measured while viewing their experience on video, and a further two participants experiencing a development of the methodology as their physiological responses were captured in real time during the intervention. The sessions were analysed by a group of five cross-disciplinary researchers to determine when significant learning episodes occurred, and the findings were that this learning was associated with powerful skin conductance responses. The qualitative element of the research entailed the participants watching themselves on video undertaking the equine intervention. They were asked to stop the video and share any changes in emotion at any point while watching. All participants experienced a positive temporal change in mood as the intervention progressed. All results supported the findings that emotional arousal occurred in relation to the participants asking the horse to perform a task. This paper will offer two novel contributions: (1) description of a new methodology for investigating the mechanism of action occurring in this type of intervention and (2) findings from the exploration of the intervention via psycho-physiological and experiential mechanisms.

Complex regional pain syndrome: a focus on the autonomic nervous system

PURPOSE

Although autonomic features are part of the diagnostic criteria for complex regional pain syndrome (CRPS), the role of the autonomic nervous system in CRPS pathophysiology has been downplayed in recent years. The purpose of this review is to redress this imbalance.

METHODS

We focus in this review on the contribution of the autonomic nervous system to CRPS pathophysiology. In particular, we discuss regional sympathetic and systemic autonomic disturbances in CRPS and the mechanisms which may underlie them, and consider links between these mechanisms, immune disturbances and pain.

RESULTS

The focused literature research revealed that immune reactions, alterations in receptor populations (e.g., upregulation of adrenoceptors and reduced cutaneous nerve fiber density) and central changes in autonomic drive seem to contribute to regional and systemic disturbances in sympathetic activity and to sympathetically maintained pain in CRPS.

CONCLUSIONS

We conclude that alterations in the sympathetic nervous system contribute to CRPS pathology. Understanding these alterations may be an important step towards providing appropriate treatments for CRPS.

Altered frontal and insular functional connectivity as pivotal mechanisms for apathy in Alzheimer's disease

BACKGROUND

Apathy is a common and early symptom in Alzheimer's disease (AD) and is linked to poorer prognosis. Theoretical interpretations of apathy implicate alterations of connections amongst fronto-striatal and limbic regions.

OBJECTIVE

To test the association between presence of apathy and patterns of brain functional connectivity in patients with clinically-established AD.

METHODS

Seventy AD patients were included. Thirty-five patients experienced apathy as defined by the screening question of the Neuropsychiatric Inventory, and thirty-five did not. All patients agreed to undergo an MRI protocol inclusive of resting-state acquisitions. The hemodynamic-dependent signal was extracted bilaterally from five regions of interest: ventromedial prefrontal cortices, anterior cingulate cortices, dorsolateral prefrontal cortices, insulae and amygdalae. t tests were run to compare connectivity maps of apathetic and non-apathetic patients. Age, education, Mini Mental State Examination score, gray matter volumes and gray matter fractions served as covariates.

RESULTS

At a p_FWE < .05 threshold, apathetic patients had reduced connectivity between the left insula and right superior parietal cortex. Apathetic patients had also increased connectivity between the right dorsolateral prefrontal seed and the right superior parietal cortex. Patients with apathy were significantly more likely to experience other psychiatric symptoms.

CONCLUSION

Our findings support a role of frontal and insular connections in coordinating value-based decisions in AD. Both down-regulation and maladaptive up-regulation mechanisms appear to be at play in these regions.

Improving interoceptive ability through the practice of power posing: A pilot study

Interoception refers to the detection and perception of signals from the inner body. Deficits in this domain have been linked to psychopathologies, prompting the search for strategies to improve this ability. Preliminary studies have shown that interoception could be enhanced through the manipulation of subjective feelings of power. We tested the effects of adopting powerful postures on different facets of interoception. Firstly, we measured the impact of a single power posing session on interoceptive ability in 41 healthy females. Then, the same participants were randomly assigned to two conditions (daily power posing practice vs. no practice). After one week the conditions alternated. Interoceptive accuracy, measured by the heartbeat tracking task, interoceptive sensibility, measured by the Body Perception Questionnaire (BPQ) and confidence ratings, as well as subjective feelings of power were assessed at baseline, after a single power posing session and after one week of training. A single power posing session significantly increased individuals' interoceptive accuracy. Also, power posing reduced individuals' scores on the BPQ after one week of daily practice and increased subjective feelings of power after one session and one week of daily practice. These findings suggest that adopting powerful postures has the potential to increase interoceptive accuracy, as well as subjective feelings of power, and to reduce interoceptive sensibility, measured by questionnaire.

Distinction of self-produced touch and social touch at cortical and spinal cord levels

The earliest way humans can learn what their body is and where the outside world begins is through the tactile sense, especially through touch between parent and baby. In this study, we demonstrated differential processing of touch from self and others at cortical and spinal levels. Our results support top-down modulation of dorsal horn somatosensory processing, as recently shown in animal studies. We provide evidence that the individual self-concept relates to differential self- vs. other-processing in the tactile domain. Self- vs. other-distinction is necessary for successful social interaction with others and for establishing a coherent self. Our results suggest an association between impaired somatosensory processing and a dysfunctional self-concept, as seen in many psychiatric disorders.

Differentiation between self-produced tactile stimuli and touch by others is necessary for social interactions and for a coherent concept of “self.” The mechanisms underlying this distinction are unknown. Here, we investigated the distinction between self- and other-produced light touch in healthy volunteers using three different approaches: fMRI, behavioral testing, and somatosensory-evoked potentials (SEPs) at spinal and cortical levels. Using fMRI, we found self–other differentiation in somatosensory and sociocognitive areas. Other-touch was related to activation in several areas, including somatosensory cortex, insula, superior temporal gyrus, supramarginal gyrus, striatum, amygdala, cerebellum, and prefrontal cortex. During self-touch, we instead found deactivation in insula, anterior cingulate cortex, superior temporal gyrus, amygdala, parahippocampal gyrus, and prefrontal areas. Deactivation extended into brain areas encoding low-level sensory representations, including thalamus and brainstem. These findings were replicated in a second cohort. During self-touch, the sensorimotor cortex was functionally connected to the insula, and the threshold for detection of an additional tactile stimulus was elevated. Differential encoding of self- vs. other-touch during fMRI correlated with the individual self-concept strength. In SEP, cortical amplitudes were reduced during self-touch, while latencies at cortical and spinal levels were faster for other-touch. We thus demonstrated a robust self–other distinction in brain areas related to somatosensory, social cognitive, and interoceptive processing. Signs of this distinction were evident at the spinal cord. Our results provide a framework for future studies in autism, schizophrenia, and emotionally unstable personality disorder, conditions where symptoms include social touch avoidance and poor self-vs.-other discrimination.