Allostasis: a model of predictive regulation

Drive competition underlies effective allostatic orchestration

Living systems ensure their fitness by self-regulating. The optimal matching of their behavior to the opportunities and demands of the ever-changing natural environment is crucial for satisfying physiological and cognitive needs. Although homeostasis has explained how organisms maintain their internal states within a desirable range, the problem of orchestrating different homeostatic systems has not been fully explained yet. In the present paper, we argue that attractor dynamics emerge from the competitive relation of internal drives, resulting in the effective regulation of adaptive behaviors. To test this hypothesis, we develop a biologically-grounded attractor model of allostatic orchestration that is embedded into a synthetic agent. Results show that the resultant neural mass model allows the agent to reproduce the navigational patterns of a rodent in an open field. Moreover, when exploring the robustness of our model in a dynamically changing environment, the synthetic agent pursues the stability of the self, being its internal states dependent on environmental opportunities to satisfy its needs. Finally, we elaborate on the benefits of resetting the model’s dynamics after drive-completion behaviors. Altogether, our studies suggest that the neural mass allostatic model adequately reproduces self-regulatory dynamics while overcoming the limitations of previous models.

Racism, shame, and stress reactivity among young black women

Black women experience disproportional rates of cardiovascular disease (CVD) warranting further exploration of CVD risk factors. Growing evidence suggests acute stress reactivity studies may elucidate the mechanisms driving psychosocial correlates of CVD risks. Race-related stress has been identified as a CVD risk factor among Black women though recent evidence suggests emotions may facilitate these risks. Black women may be vulnerable to shame related to frequent racist experiences. Yet, no study to date has examined racism, shame, and stress reactivity in this population. The current study utilized mixed linear models to test for time and group effects of racism and shame on stress reactivity (e.g., cortisol and C-reactive protein [CRP]) among 34 Black women who completed the Trier Social Stress Test. Tests for two-way interactions (i.e., shame by racism) were also performed. Significant time and group effects were observed for shame and racism on stress reactivity. Black women who experienced greater lifetime racism, stress appraised, but lower racism during the past year, exhibited greater CRP responses. Black women who experienced high levels of shame and racism during the past year and their lifetime demonstrated greater cortisol reactivity. These results prompt further research on racism and shame as CVD risk factors among Black women.

The energetic cost of allostasis and allostatic load

Chronic psychosocial stress increases disease risk and mortality, but the underlying mechanisms remain largely unclear. Here we outline an energy-based model for the transduction of chronic stress into disease over time. The energetic model of allostatic load (EMAL) emphasizes the energetic cost of allostasis and allostatic load, where the "load" is the additional energetic burden required to support allostasis and stress-induced energy needs. Living organisms have a limited capacity to consume energy. Overconsumption of energy by allostatic brain-body processes leads to hypermetabolism, defined as excess energy expenditure above the organism's optimum. In turn, hypermetabolism accelerates physiological decline in cells, laboratory animals, and humans, and may drive biological aging. Therefore, we propose that the transition from adaptive allostasis to maladaptive allostatic states, allostatic load, and allostatic overload arises when the added energetic cost of stress competes with longevity-promoting growth, maintenance, and repair. Mechanistically, the energetic restriction of growth, maintenance and repair processes leads to the progressive wear-and-tear of molecular and organ systems. The proposed model makes testable predictions around the physiological, cellular, and sub-cellular energetic mechanisms that transduce chronic stress into disease risk and mortality. We also highlight new avenues to quantify allostatic load and its link to health across the lifespan, via the integration of systemic and cellular energy expenditure measurements together with classic allostatic load biomarkers.

The future of individualized cardiovascular care: how wearables could be integrated to improve outcomes

Personalized medicine is a concept all clinicians must strive to deliver. Recent advances in technology increasingly offer new opportunities to personalize care, not least in cardiovascular medicine. Health trackers and wearables are technologies in an explosive phase of development. They allow accurate and continuous measurement of bio-data, recorded and analysed using apps and mobile devices. However, although there is huge potential, most physicians and healthcare organizations are yet to realize the value of integrating wearables into routine clinical practice. We discuss how this state-of-the-art technology can support patients in making meaningful lifestyle changes and revolutionize the future of cardiovascular medicine.

Use of omics analysis for low-dose radiotoxicology and health risk assessment: the case of uranium

Exposure to environmental pollution and the increase in the incidence of multifactorial diseases in the population have become health problems for industrialized countries. In this context, the question of the health impact of exposure to these pollutants is not clearly identified in the low-dose range. This article looks at this problem using the example of preclinical studies of the effects of chronic low-dose exposure to uranium in rats. These studies demonstrate the value of molecular screening analyses (omics) and multimodal integrative approaches, of which the extreme sensitivity and breadth of observation spectrum make it possible to observe all the biological processes affected and the mechanisms of action triggered at the molecular level by exposure to low doses. They also show the value of these analytical approaches for finding diagnostic biomarkers or indicators of prognosis, which can be necessary to evaluate a risk. Finally, the results of these studies raise the question of the health risk caused by epigenomic deregulations occurring during critical developmental phases and their potential contribution to the development of chronic diseases that are metabolic in origin or to the development of certain cancer liable in the long term to affect the exposed adult and possibly its progeny.

New insights on the correspondence between subjective affective experience and physiological responses from representational similarity analysis

Classical views suggest that experienced affect is related to a specific bodily response, whereas recent perspectives challenge this view postulating that similar affective experiences rather evoke different physiological responses. To further advance this debate in the field, we used representational similarity analysis to investigate the correspondence between subjective affect (arousal and valence ratings) and physiological reactions (skin conductance response [SCR], startle blink response, heart rate, and corrugator activity) across various emotion induction contexts (picture viewing task, sound listening task, and imagery task). Significant similarities were exclusively observed between SCR and arousal in the picture viewing task. However, none of the other physiological measures showed a significant relation with valence and arousal ratings in any of the tasks. These findings are discussed within the framework of the Populations hypothesis, suggesting that physiological responses do not depend on the experienced affect but are directly associated with the context in which they are evoked.

A predictive coding framework of allostatic-interoceptive overload in frontotemporal dementia

Recent allostatic-interoceptive explanations using predictive coding models propose that efficient regulation of the body's internal milieu is necessary to correctly anticipate environmental needs. We review this framework applied to understanding behavioral variant frontotemporal dementia (bvFTD) considering both allostatic overload and interoceptive deficits. First, we show how this framework could explain divergent deficits in bvFTD (cognitive impairments, behavioral maladjustment, brain atrophy, fronto-insular-temporal network atypicality, aberrant interoceptive electrophysiological activity, and autonomic disbalance). We develop a set of theory-driven predictions based on levels of allostatic interoception associated with bvFTD phenomenology and related physiopathological mechanisms. This approach may help further understand the disparate behavioral and physiopathological dysregulations of bvFTD, suggesting targeted interventions and strengthening clinical models of neurological and psychiatric disorders.

A Network Approach to Assessing the Relationship between Discrimination and Daily Emotion Dynamics

Discrimination-health research has been critiqued for neglecting the endogeneity of reports of discrimination to negative affect and the multidimensionality of mental health. To address these challenges, we model discrimination’s relationship to multiple psychological variables without directional constraints. Using time-dense data to identify associational network structures allows for joint testing of the social stress hypothesis, prominent in discrimination-health literature, and the negativity bias hypothesis, an endogeneity critique rooted in social psychology. Our results show discrimination predicts negative emotions from day-to-day but not vice versa, indicating that racial discrimination is a risk factor and not symptom of negative emotion. Furthermore, we identify sadness, guilt, hostility, and fear as a locus of interrelated emotions sensitive to racism-related stressors that emerges over time. Thus, we find support for what race scholars have argued for 120+ years in a model without a priori directional restrictions and then build on this work by empirically identifying cascading mental health consequences of discrimination.

Allostasis as a core feature of hierarchical gradients in the human brain

This paper integrates emerging evidence from two broad streams of scientific literature into one common framework: (a) hierarchical gradients of functional connectivity that reflect the brain's large-scale structural architecture (e.g., a lamination gradient in the cerebral cortex); and (b) approaches to predictive processing and one of its specific instantiations called allostasis (i.e., the predictive regulation of energetic resources in the service of coordinating the body's internal systems). This synthesis begins to sketch a coherent, neurobiologically inspired framework suggesting that predictive energy regulation is at the core of human brain function, and by extension, psychological and behavioral phenomena, providing a shared vocabulary for theory building and knowledge accumulation.

Embodied feelings-A meta-analysis on the relation of emotion intensity perception and interoceptive accuracy

Emotion theories emphasize the relevance of (predicted) bodily changes for the construction of one's own emotions and an extensive overlap of brain regions involved during emotion intensity perception and somatosensory processing. The ability to accurately perceive bodily changes and its impact on the perception of emotion intensity has been studied for at least 40 years. The results of previous studies were summarized in a meta-analysis to examine how closely interoceptive accuracy and emotion intensity are related. After a systematic literature search, 4036 studies were screened for eligibility. Only studies assessing adults from general population samples were considered. Samples recruited to examine mental disorders or neurological conditions were excluded. Thirty studies with a quantifiable measure for the relation of interoceptive accuracy and emotion intensity perception were included in the meta-analysis. Interoceptive accuracy was significantly related with emotion intensity perception, when emotions were experimentally induced (k= 22, r= 0.15). However, the relationship was only found when IAPS images (k= 9, r= 0.33) or facial expressions (k= 3, r= 0.24) were used for emotion induction. No significant relation was found in studies without emotion induction (k= 19, r = -0.007). There was considerable bias, varying dependent on bias assessment method, study protocol and examined risk of bias dimension. We discuss the impact of differences in study protocols, review the operationalization of interoceptive accuracy critically and derive directions for future research.

How is emotional resonance achieved in storytellings of sadness/distress?

Storytelling pivots around stance seen as a window unto emotion: storytellers project a stance expressing their emotion toward the events and recipients preferably mirror that stance by affiliating with the storyteller’s stance. Whether the recipient’s affiliative stance is at the same time expressive of his/her emotional resonance with the storyteller and of emotional contagion is a question that has recently attracted intriguing research in Physiological Interaction Research. Connecting to this line of inquiry, this paper concerns itself with storytellings of sadness/distress. Its aim is to identify factors that facilitate emotion contagion in storytellings of sadness/distress and factors that impede it. Given the complexity and novelty of this question, this study is designed as a pilot study to scour the terrain and sketch out an interim roadmap before a larger study is undertaken. The data base is small, comprising two storytellings of sadness/distress. The methodology used to address the above research question is expansive: it includes CA methods to transcribe and analyze interactionally relevant aspects of the storytelling interaction; it draws on psychophysiological measures to establish whether and to what degree emotional resonance between co-participants is achieved. In discussing possible reasons why resonance is (not or not fully) achieved, the paper embarks on an extended analysis of the storytellers’ multimodal storytelling performance (reenactments, prosody, gaze, gesture) and considers factors lying beyond the storyteller’s control, including relevance, participation framework, personality, and susceptibility to emotion contagion.

A healthy settings approach to addressing painogenic environments: New perspectives from health promotion

Structural approaches to promoting health focus on policies and practices affecting health at the community level and concentrate on systems and forces of society, including distribution of power, that foster disadvantage and diminish health and well-being. In this paper we advocate consideration of structural approaches to explore macro level influences on the burden of persistent pain on society. We argue that health promotion is an appropriate discipline to ameliorate painogenic environments and that a “settings approach” offers a crucial vehicle to do this. We encourage consideration of socio-ecological frameworks to explore factors affecting human development at individual, interpersonal, organizational, societal, and environmental levels because persistent pain is multifaceted and complex and unlikely to be understood from a single level of analysis. We acknowledge criticisms that the structural approach may appear unachievable due to its heavy reliance on inter-sectoral collaboration. We argue that a settings approach may offer solutions because it straddles “practical” and cross-sectorial forces impacting on the health of people. A healthy settings approach invests in social systems where health is not the primary remit and utilises synergistic action between settings to promote greater health gains. We offer the example of obesogenic environments being a useful concept to develop strategies to tackle childhood obesity in school-settings, community-settings, shops, and sports clubs; and that this settings approach has been more effective than one organisation tackling the issue in isolation. We argue that a settings approach should prove useful for understanding painogenic environments and tackling the burden of persistent pain.

Active neural coordination of motor behaviors with internal states

The brain continuously coordinates skeletomuscular movements with internal physiological states like arousal, but how is this coordination achieved? One possibility is that the brain simply reacts to changes in external and/or internal signals. Another possibility is that it is actively coordinating both external and internal activities. We used functional ultrasound imaging to capture a large medial section of the brain, including multiple cortical and subcortical areas, in marmoset monkeys while monitoring their spontaneous movements and cardiac activity. By analyzing the causal ordering of these different time series, we found that information flowing from the brain to movements and heart-rate fluctuations were significantly greater than in the opposite direction. The brain areas involved in this external versus internal coordination were spatially distinct, but also extensively interconnected. Temporally, the brain alternated between network states for this regulation. These findings suggest that the brain's dynamics actively and efficiently coordinate motor behavior with internal physiology.

Two modes of being together: The levels of intersubjectivity and human relatedness in neuroscience and psychoanalytic thinking

The notion of intersubjectivity has achieved a primary status in contemporary psychoanalytic debate, stimulating new theoretical proposals as well as controversies. This paper presents an overview of the main contributions on inter-subjectivity in the field of neurosciences. In humans as well as-probably-in other species, the ability for emotional resonance is guaranteed early in development. Based on this capacity, a primary sense of connectedness is established that can be defined inter-subjective in that it entails sharing affective states and intentions with caregivers. We propose to define such a form of inter-subjectivity as contingent, since the infant's early abilities for resonance do not imply the more generalized capacity to permanently conceive of the relationship outside the realm of current interactions and the infant-caregiver's mutual correspondence of internal states. This form of connection, hence, results in a self-referential, bodily, and affectively codified, context- and time dependent, like-me experience of interactions. The gradual maturation of brain structures and processes as well as interactive experiences allow proper intersubjectivity exchanges, grounded on new intentional and representational capacities, to evolve. In this more mature form of intersubjectivity, the individual is allowed to conceive of her own psychic space both as distinct and as possibly connected with the other's contents and experience, even in the absence of current behavioral indicators of such correspondence. This multi-layered model of intersubjectivity, which is embraced by current neuroscience research, seems to allow for new interpretations of psychoanalytic models of human relatedness based upon classic clinical observations.

The application of allostasis and allostatic load in animal species: A scoping review

Principles of allostasis and allostatic load have been widely applied in human research to assess the impacts of chronic stress on physiological dysregulation. Over the last few decades, researchers have also applied these concepts to non-human animals. However, there is a lack of uniformity in how the concept of allostasis is described and assessed in animals. The objectives of this review were to: 1) describe the extent to which the concepts of allostasis and allostatic load are applied theoretically to animals, with a focus on which taxa and species are represented; 2) identify when direct assessments of allostasis or allostatic load are made, which species and contexts are represented, what biomarkers are used, and if an allostatic load index was constructed; and 3) detect gaps in the literature and identify areas for future research. A search was conducted using CABI, PubMed, Agricola, and BIOSIS databases, in addition to a complementary hand-search of 14 peer-reviewed journals. Search results were screened, and articles that included non-human animals, as well as the terms “allostasis” or “allostatic” in the full text, were included. A total of 572 articles met the inclusion criteria (108 reviews and 464 peer-reviewed original research). Species were represented across all taxa. A subset of 63 publications made direct assessments of allostatic load. Glucocorticoids were the most commonly used biomarker, and were the only biomarker measured in 25 publications. Only six of 63 publications (9.5%) constructed an allostatic load index, which is the preferred methodology in human research. Although concepts of allostasis and allostatic load are being applied broadly across animal species, most publications use single biomarkers that are more likely indicative of short-term rather than chronic stress. Researchers are encouraged to adopt methodologies used in human research, including the construction of species-specific allostatic load indexes.

Neurofeedback and neural self-regulation: a new perspective based on allostasis

The field of neurofeedback training (NFT) has seen growing interest and an expansion of scope, resulting in a steadily increasing number of publications addressing different aspects of NFT. This development has been accompanied by a debate about the underlying mechanisms and expected outcomes. Recent developments in the understanding of psychophysiological regulation have cast doubt on the validity of control systems theory, the principal framework traditionally used to characterize NFT. The present article reviews the theoretical and empirical aspects of NFT and proposes a predictive framework based on the concept of allostasis. Specifically, we conceptualize NFT as an adaptation to changing contingencies. In an allostasis four-stage model, NFT involves (a) perceiving relations between demands and set-points, (b) learning to apply collected patterns (experience) to predict future output, (c) determining efficient set-points, and (d) adapting brain activity to the desired ("set") state. This model also identifies boundaries for what changes can be expected from a neurofeedback intervention and outlines a time frame for such changes to occur.

Machines That Feel and Think: The Role of Affective Feelings and Mental Action in (Artificial) General Intelligence

What role do affective feelings (feelings/emotions/moods) play in adaptive behaviour? What are the implications of this for understanding and developing artificial general intelligence? Leading theoretical models of brain function are beginning to shed light on these questions. While artificial agents have excelled within narrowly circumscribed and specialised domains, domain-general intelligence has remained an elusive goal in artificial intelligence research. By contrast, humans and nonhuman animals are characterised by a capacity for flexible behaviour and general intelligence. In this article I argue that computational models of mental phenomena in predictive processing theories of the brain are starting to reveal the mechanisms underpinning domain-general intelligence in biological agents, and can inform the understanding and development of artificial general intelligence. I focus particularly on approaches to computational phenomenology in the active inference framework. Specifically, I argue that computational mechanisms of affective feelings in active inference-affective self-modelling-are revealing of how biological agents are able to achieve flexible behavioural repertoires and general intelligence. I argue that (i) affective self-modelling functions to "tune" organisms to the most tractable goals in the environmental context; and (ii) affective and agentic self-modelling is central to the capacity to perform mental actions in goal-directed imagination and creative cognition. I use this account as a basis to argue that general intelligence of the level and kind found in biological agents will likely require machines to be implemented with analogues of affective self-modelling.

Psychobiological effects of chronic ethnic discrimination in Turkish immigrants: Stress responses to standardized face-to-face discrimination in the laboratory

OBJECTIVE

Ethnic discrimination negatively affects the health of ethnic minorities. The dysregulation of psychobiological stress systems, such as the autonomic nervous system (ANS) or the hypothalamic-pituitary-adrenal (HPA) axis, might be an intermediary in this association and chronicity of ethnic discrimination may matter. We studied stress responses to a standardized discriminatory event in Turkish immigrants living in Austria.

BACKGROUND

Seventy-two male Turkish immigrants were recruited; n = 35 had experienced high levels of ethnic discrimination (high), n = 37 infrequent ethnic discrimination (low). During a two-hour laboratory appointment, they underwent a previously validated 10-minute ethnic discrimination paradigm, i.e., a simulated physician's consultation with verbal and non-verbal discriminatory cues. Perceived stress, perceived discrimination, salivary cortisol, and alpha-amylase were assessed seven times, and ANS measures (heart rate, heart rate variability, and electrodermal activity) were measured continuously. In addition, hair cortisol concentrations were determined.

RESULTS

The ethnic discrimination paradigm elicited stress responses across all outcomes in both groups. Compared to the low group, the high group reported higher levels of perceived stress and discrimination, exhibited a less steep increase in cortisol in response to the paradigm, and showed higher hair cortisol concentrations. No group differences were found regarding ANS measures.

CONCLUSIONS

The combination of high subjective stress, flattened cortisol responses, and relatively high hair cortisol concentrations may indicate a dysregulation of the HPA axis in chronic ethnic discrimination. A better understanding of the psychobiological effects of chronic ethnic discrimination is crucial given that alterations in stress response systems may, over time, lead to illness and ultimately to substantial health inequities in ethnic minorities.

Acoustic Delicing of Atlantic Salmon (Salmo salar): Fish Welfare and Salmon Lice (Lepeophtheirus salmonis) Dynamics

Acoustic lice treatment (AcuLice) is a newly developed system, which uses a composite acoustic sound image with low-frequency sound to remove salmon lice (Lepeophtheirus salmonis) from Atlantic salmon (Salmo salar). This field study documents the stress effects on Atlantic salmon and the effect on salmon lice dynamics during large-scale use of the AcuLice system. The effect of the AcuLice treatment on salmon lice dynamics was measured by weekly salmon lice counting at the facilities from mid-summer 2019 to late-spring 2020. The number of salmon lice treatments in the same period was also compared to a reference group. In addition, the number of weeks until the first salmon lice treatment (mechanical treatment) was compared between the two groups. Apart from a slight increase in plasma glucose, no significant differences were observed in the primary, secondary, or tertiary stress responses measured. For the mature female salmon lice, a significantly lower number (mean ± SEM) was shown for the AcuLice group (0.24 ± 0.03) compared to the reference group (0.44 ± 0.04). In addition, a lower number (mean ± SEM) of salmon lice treatments and a longer production period before the first salmon lice treatment occurred was observed at the AcuLice facilities (33.2 ± 3 weeks) compared to the reference facilities (20.3 ± 2 weeks). These data suggest that the use of the AcuLice system reduces the need for traditional salmon lice treatments with no added stress to the fish.

Brain Neural Underpinnings of Interoception and Decision-Making in Alzheimer's Disease: A Narrative Review

This study reviews recent literature on interoception directing decision-making in Alzheimer's disease (AD). According to the somatic marker hypothesis, signals from the internal body direct decision-making and involve the ventromedial prefrontal cortex (vmPFC). After reviewing relevant studies, we summarize the brain areas related to interoception and decision-making (e.g., vmPFC, hippocampus, amygdala, hypothalamus, anterior cingulate cortex, and insular cortex) and their roles in and relationships with AD pathology. Moreover, we outline the relationship among interoception, the autonomic nervous system, endocrine system, and AD pathology. We discuss that impaired interoception leads to decreased decision-making ability in people with AD from the perspective of brain neural underpinning. Additionally, we emphasize that anosognosia or reduced self-awareness and metacognition in AD are remarkably congruent with the malfunction of the autonomic nervous system regulating the interoceptive network. Furthermore, we propose that impaired interoception may contribute to a loss in the decision-making ability of patients with AD. However, there still exist empirical challenges in confirming this proposal. First, there has been no standardization for measuring or improving interoception to enhance decision-making ability in patients with AD. Future studies are required to better understand how AD pathology induces impairments in interoception and decision-making.

Changes in Affect Integration and Internalizing Symptoms After Time-Limited Intersubjective Child Psychotherapy—A Pilot Study

Time-limited intersubjective child-psychotherapy (TIC) is an intensive, structured right-brain oriented therapeutic approach for children and caregivers aimed at both symptom reduction and strengthening core developmental processes such as affect integration. This is the first study to investigate changes in internalizing symptoms and affect integration after TIC. Thirty-three children between 9 and 13 years with internalizing difficulties were assessed after 10 h of TIC. Internalizing symptoms were assessed through the child behavior checklist and affect integration with the affect consciousness interview (ACI). Scores from the children with internalizing difficulties were modeled in a mixed linear model along with data from a control group without internalizing difficulties (n = 24) to control for effects of time and learning. Affect integration increased significantly from time 1 to time 2 in the children with internalizing problems, but not in the control children. Internalizing symptoms were also significantly reduced in the children with internalizing difficulties from time 1 to time 2. The results indicate that TIC may contribute to a decrease in symptoms along with an increase in affect integration in children with internalizing difficulties, making the children better able to notice, tolerate and communicate affective states. This can, in turn, aid development and day-to-day regulation and interactions. The article explores key elements of TIC, such as affective attunement, relational repair, and work with caregivers using one of the individual therapies in the study as an example. The article argues that TIC represents a right-hemisphere to right-hemisphere therapeutic approach to healing that can both enhance important common therapeutic factors such a relation and alliance and bring about growth-promoting change.

A new framework for modeling the bidirectional interplay between brain oscillations and cardiac sympathovagal activity

The study of functional brain-heart interplay (BHI) aims to describe the dynamical interactions between central and peripheral autonomic nervous systems. Here, we introduce the Sympathovagal Synthetic Data Generation Model, which constitutes a new computational framework for the assessment of functional BHI. The model estimates the bidirectional interplay with novel quantifiers of cardiac sympathovagal activity gathered from Laguerre expansions of RR series (from the ECG), as an alternative to the classical spectral analysis. The main features of the model are time-varying coupling coefficients linking Electroencephalography (EEG) oscillations and cardiac sympathetic or parasympathetic activity, for either ascending or descending direction of the information flow. In this proof-of-concept study, functional BHI is quantified in the direction from-heart-to-brain, on data from 16 human volunteers undergoing a cold-pressor test. Results show that thermal stress induces heart-to-brain functional interplay originating from sympathetic and parasympathetic activities and sustaining EEG oscillations mainly in the δ and γ bands. The proposed computational framework could provide a viable tool for the functional assessment of the causal interplay between cortical and cardiac sympathovagal dynamics.

Allostatic-Interoceptive Overload in Frontotemporal Dementia

BACKGROUND

The predictive coding theory of allostatic-interoceptive load states that brain networks mediating autonomic regulation and interoceptive-exteroceptive balance regulate the internal milieu to anticipate future needs and environmental demands. These functions seem to be distinctly compromised in behavioral variant frontotemporal dementia (bvFTD), including alterations of the allostatic-interoceptive network (AIN). Here, we hypothesize that bvFTD is typified by an allostatic-interoceptive overload.

METHODS

We assessed resting-state heartbeat evoked potential (rsHEP) modulation as well as its behavioral and multimodal neuroimaging correlates in patients with bvFTD relative to healthy control subjects and patients with Alzheimer's disease (N = 94). We measured 1) resting-state electroencephalography (to assess the rsHEP, prompted by visceral inputs and modulated by internal body sensing), 2) associations between rsHEP and its neural generators (source location), 3) cognitive disturbances (cognitive state, executive functions, facial emotion recognition), 4) brain atrophy, and 5) resting-state functional magnetic resonance imaging functional connectivity (AIN vs. control networks).

RESULTS

Relative to healthy control subjects and patients with Alzheimer's disease, patients with bvFTD presented more negative rsHEP amplitudes with sources in critical hubs of the AIN (insula, amygdala, somatosensory cortex, hippocampus, anterior cingulate cortex). This exacerbated rsHEP modulation selectively predicted the patients' cognitive profile (including cognitive decline, executive dysfunction, and emotional impairments). In addition, increased rsHEP modulation in bvFTD was associated with decreased brain volume and connectivity of the AIN. Machine learning results confirmed AIN specificity in predicting the bvFTD group.

CONCLUSIONS

Altogether, these results suggest that bvFTD may be characterized by an allostatic-interoceptive overload manifested in ongoing electrophysiological markers, brain atrophy, functional networks, and cognition.

Unbalanced functional connectivity at rest affects the ERP correlates of affective prediction in high intolerance of uncertainty individuals: A high density EEG investigation

In a recent study we outlined the link between Intolerance of Uncertainty (IU) and the neural correlates of affective predictions, as constructed by the brain (generation stage) to prepare to relevant stimuli (implementation stage), and update predictive models according to incoming stimuli (updating stage). In this study we further explored whether the brain's functional organization at rest can modulate neural activity elicited within an emotional S1-S2 paradigm as a function of IU and uncertainty of S1-S2 contingencies. We computed resting state functional connectivity (RS-FC) from a 3-min resting period recorded with high density EEG, and we tested whether RS graph theory nodal measures (i.e., strength, clustering coefficient, betweenness centrality) predicted in-task ERP modulation as a function of IU. We found that RS-FC differently predicted in-task ERPs within the generation and updating stages. Higher IU levels were associated to altered RS-FC patterns within both domain-specific (i.e., right superior temporal sulcus) and domain-general regions (i.e., right orbitofrontal cortex), predictive of a reduced modulation of in-task ERPs in the generation and updating stages. This is presumably ascribable to an unbalancing between synchronization and integration within these regions, which may disrupt the exchange of information between top-down and bottom-up pathways. This altered RS-FC pattern may in turn result in the construction of less efficient affective predictions and a reduced ability to deal with contextual uncertainty in individuals high in IU.

A new science of emotion: implications for functional neurological disorder

Functional neurological disorder reflects impairments in brain networks leading to distressing motor, sensory and/or cognitive symptoms that demonstrate positive clinical signs on examination incongruent with other conditions. A central issue in historical and contemporary formulations of functional neurological disorder has been the mechanistic and aetiological role of emotions. However, the debate has mostly omitted fundamental questions about the nature of emotions in the first place. In this perspective article, we first outline a set of relevant working principles of the brain (e.g. allostasis, predictive processing, interoception and affect), followed by a focused review of the theory of constructed emotion to introduce a new understanding of what emotions are. Building on this theoretical framework, we formulate how altered emotion category construction can be an integral component of the pathophysiology of functional neurological disorder and related functional somatic symptoms. In doing so, we address several themes for the functional neurological disorder field including: (i) how energy regulation and the process of emotion category construction relate to symptom generation, including revisiting alexithymia, 'panic attack without panic', dissociation, insecure attachment and the influential role of life experiences; (ii) re-interpret select neurobiological research findings in functional neurological disorder cohorts through the lens of the theory of constructed emotion to illustrate its potential mechanistic relevance; and (iii) discuss therapeutic implications. While we continue to support that functional neurological disorder is mechanistically and aetiologically heterogenous, consideration of how the theory of constructed emotion relates to the generation and maintenance of functional neurological and functional somatic symptoms offers an integrated viewpoint that cuts across neurology, psychiatry, psychology and cognitive-affective neuroscience.

An insula hierarchical network architecture for active interoceptive inference

In the brain, the insular cortex receives a vast amount of interoceptive information, ascending through deep brain structures, from multiple visceral organs. The unique hierarchical and modular architecture of the insula suggests specialization for processing interoceptive afferents. Yet, the biological significance of the insula's neuroanatomical architecture, in relation to deep brain structures, remains obscure. In this opinion piece, we propose the Insula Hierarchical Modular Adaptive Interoception Control (IMAC) model to suggest that insula modules (granular, dysgranular and agranular), forming parallel networks with the prefrontal cortex and striatum, are specialized to form higher order interoceptive representations. These interoceptive representations are recruited in a context-dependent manner to support habitual, model-based and exploratory control of visceral organs and physiological processes. We discuss how insula interoceptive representations may give rise to conscious feelings that best explain lower order deep brain interoceptive representations, and how the insula may serve to defend the body and mind against pathological depression.

Neuronal metabolism in learning and memory: The anticipatory activity perspective

Current research on the molecular mechanisms of learning and memory is based on the "stimulus-response" paradigm, in which the neural circuits connecting environmental events with behavioral responses are strengthened. By contrast, cognitive and systems neuroscience emphasize the intrinsic activity of the brain that integrates information, establishes anticipatory actions, executes adaptive actions, and assesses the outcome via regulatory feedback mechanisms. We believe that the difference in the perspectives of systems and molecular studies is a major roadblock to further progress toward understanding the mechanisms of learning and memory. Here, we briefly overview the current studies in molecular mechanisms of learning and memory and propose that studying the predictive properties of neuronal metabolism will significantly advance our knowledge of how intrinsic, predictive activity of neurons shapes a new learning event. We further suggest that predictive metabolic changes in the brain may also take place in non-neuronal cells, including those of peripheral tissues. Finally, we present a path forward toward more in-depth studies of the role of cell metabolism in learning and memory.

Affect and Social Judgment: The Roles of Physiological Reactivity and Interoceptive Sensitivity

Humans imbue the objects of their perception with affective meaning, a phenomenon called affective realism. The affective realism hypothesis proposes that a brain continually predicts the meaning of sensations (e.g., identifying a sound as a siren, or a visual array as a face) in part by representing the current state of the body and the immediate physiological impact that similar sensory events have entailed in the past. However, the precise contribution of physiological activity to experiences of affective realism remains unknown. In the present study, participants' peripheral physiological activity was recorded while they made social evaluative judgments of target faces displaying neutral expressions. Target faces were shown concurrent with affective images that were suppressed from reportable awareness using continuous flash suppression. Results revealed evidence of affective realism-participants judged target faces more positively when paired with suppressed positive stimuli than suppressed negative stimuli-but this effect was significantly less pronounced among individuals higher in cardiac interoceptive sensitivity. Moreover, while some modest differences in peripheral physiological activity were observed across suppressed affective stimulus conditions, physiological reactivity to affective stimuli did not directly predict social evaluative judgments. We explore the implications of these findings with respect to both theories of emotion and theories detailing a role for interoception in experiences of first-person subjectivity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42761-022-00114-9.

Arousal elevation drives the development of oscillatory vocal output

Adult behaviors, such as vocal production, often exhibit temporal regularity. In contrast, their immature forms are more irregular. We ask whether the coupling of motor behaviors with arousal changes gives rise to temporal regularity: Do they drive the transition from variable to regular motor output over the course of development? We used marmoset monkey vocal production to explore this putative influence of arousal on the nonlinear changes in their developing vocal output patterns. Based on a detailed analysis of vocal and arousal dynamics in marmosets, we put forth a general model incorporating arousal and auditory feedback loops for spontaneous vocal production. Using this model, we show that a stable oscillation can emerge as the baseline arousal increases, predicting the transition from stochastic to periodic oscillations observed during marmoset vocal development. We further provide a solution for how this model can explain vocal development as the joint consequence of energetic growth and social feedback. Together, we put forth a plausible mechanism for the development of arousal-mediated adaptive behavior.NEW & NOTEWORTHY The development of motor behaviors, and the influence of energetic and social factors on it, has long been of interest, yet we lack an integrated picture of how these different systems may interact. Through the lens of vocal development in infant marmosets, this study offers a solution for social behavior development by linking motor production with arousal states. Increases in arousal can drive the system out of stochastic states toward oscillatory dynamics ready for communication.

"Moving on Up? Neighborhood Status and Racism-Related Distress among Black Americans"

At all levels of socioeconomic status, Black Americans can expect to live shorter and sicker lives than their White counterparts. This study advances the perspective that anti-Black stigma from Whites precludes Blacks from reaping the full health rewards of higher status, particularly within the context of neighborhoods. To test this hypothesis, I merge census data with rich survey and biomarker data from the Nashville Stress and Health Study, a representative sample of Black and White adults from Davidson County, Tennessee (n = 1,252). Initially, I find that Blacks who reside in higher-status and mostly White communities exhibit lower levels of neuroendocrine stress hormones, relative to their peers living in disadvantaged Black neighborhoods. But Blacks in higher-status areas also report more perceived discrimination. In turn, perceived discrimination is associated with chronic bodily pain, as well as elevated stress hormones and blood pressure tied to high goal-striving stress, or fears of being blocked from reaching life goals. After accounting for racism-related stressors, Blacks exhibit comparable levels of physiological distress regardless of neighborhood context. The inverse is true for Whites, who report fewer stressors in higher-status neighborhoods, and less physiological distress than Blacks overall. Findings are discussed within the context of social evolutionary theories of the human brain and are dovetailed with broader racial health disparities in the United States.

Counteracting Health Risks by Modulating Homeostatic Signaling

Homeostasis was initially conceptualized by Bernard and Cannon around a century ago as a steady state of physiological parameters that vary within a certain range, such as blood pH, body temperature, and heart rate^1,2. The underlying mechanisms that maintain homeostasis are explained by negative feedbacks that are executed by the neuronal, endocrine, and immune systems. At the cellular level, homeostasis, such as that of redox and energy steady state, also exists and is regulated by various cell signaling pathways. The induction of homeostatic mechanism is critical for human to adapt to various disruptive insults (stressors); while on the other hand, adaptation occurs at the expense of other physiological processes and thus runs the risk of collateral damages, particularly under conditions of chronic stress. Conceivably, anti-stress protection can be achieved by stressor-mimicking medicinals that elicit adaptive responses prior to an insult and thereby serve as health risk countermeasures; and in situations where maladaptation may occur, downregulating medicinals could be used to suppress the responses and prevent subsequent pathogenesis. Both strategies are preemptive interventions particularly suited for individuals who carry certain lifestyle, environmental, or genetic risk factors. In this article, we will define and characterize a new modality of prophylactic intervention that forestalls diseases via modulating homeostatic signaling. Moreover, we will provide evidence from the literature that support this concept and distinguish it from other homeostasis-related interventions such as adaptogen, hormesis, and xenohormesis.

Allostasis, Action, and Affect in Depression: Insights from the Theory of Constructed Emotion

The theory of constructed emotion is a systems neuroscience approach to understanding the nature of emotion. It is also a general theoretical framework to guide hypothesis generation for how actions and experiences are constructed as the brain continually anticipates metabolic needs and attempts to meet those needs before they arise (termed allostasis). In this review, we introduce this framework and hypothesize that allostatic dysregulation is a trans-disorder vulnerability for mental and physical illness. We then review published findings consistent with the hypothesis that several symptoms in major depressive disorder (MDD), such as fatigue, distress, context insensitivity, reward insensitivity, and motor retardation, are associated with persistent problems in energy regulation. Our approach transforms the current understanding of MDD as resulting from enhanced emotional reactivity combined with reduced cognitive control and, in doing so, offers novel hypotheses regarding the development, progression, treatment, and prevention of MDD.

Enacting Gender: An Enactive-Ecological Account of Gender and Its Fluidity

This paper aims to show that genders are enacted, by providing an account of how an individual can be said to enact a gender and explaining how, consequently, genders can be fluid. On the enactive-ecological view we defend, individuals first and foremost perceive the world as fields of affordances, that is, structured sets of action possibilities. Fields of natural affordances offer action possibilities because of the natural properties of organisms and environments. Handles offer graspability to humans because of physical-structural properties of handles and the anatomical-physiological properties of humans. Although humans live in fields of bodily, action, and cultural affordances, our work focuses on cultural affordances, where action possibilities are offered to individuals because of the normative responses of individuals in that culture. Knocking on a door affords entrance because knocking provides cultured individuals on the other side of the door an affordance to which they themselves behave normatively. Usually, behaving normatively in response to cultural affordances brings about sequences of perception-action loops, which we will call "scripts": for instance, closed doors afford knocking, which affords the individual inside opening the door, which affords an interpersonal meeting, which (may) afford entrance. Although the notion of script has a strong cognitivist flavor, one of the aims of the paper to provide an ecological account of scripts, to show that what cognitivists viewed as representations (or representational structures) are in fact environmentally structured perception-action loops. On our account of gender, gendered cultures build and maintain gendered cultural affordance landscapes, that is, landscapes in which the action possibilities individuals face are normed according to a specific body type or situation; most often (assigned) biological sex. Individuals enact a given gender when they come to perceive the affordances reserved for one gender by their culture and respond in the culturally normative way, thus enacting gendered sequences of perception-action loops (i.e., gendered scripts). With the shifting landscapes of cultural affordances brought about by several recent social, technological, and epistemic developments in some cultures, the gendered landscapes of affordances offered to individuals in these cultures have become more varied and less rigid, thus increasing the variety and flexibility of scripts individuals can enact. This entails that individuals in such cultures have an increased possibility for gender fluidity, which may in part explain the increasing number of people currently identifying outside the binary.

The Clinical Science of Euthymia: A Conceptual Map

Euthymia is a trans-diagnostic construct characterized by lack of mood disturbances; presence of positive affect; balance of psychological well-being dimensions, flexibility, consistency, and resistance to stress. The aim of this critical review is to draw a conceptual map of euthymia. Relationships with other constructs, continuum between euthymia and dysthymia with discomfort as an intermediate area, associations with lifestyle, clinimetric assessment, role of psychotherapeutic interventions, establishment of therapeutic targets, and neurobiological mechanisms are discussed. The model is based on the bipolar nature of well-being dimensions. Euthymia means using allostasis optimally and maintaining a healthy balance that promotes positive aspects of brain and body health through health-promoting behaviors. It may provide a framework for a renewed definition of recovery, for measuring treatment outcome and for targeting interventions, including the sequential administration of therapeutic components. Clinical assessment requires a clinimetric approach encompassing a broad range of aspects, such as allostatic load and lifestyle behaviors, all interacting with each other and contributing to the euthymia/dysthymia balance. Clinimetric indices for assessing euthymia (the Clinical Interview for Euthymia and the Euthymia Scale) and related constructs (the Clinical Interview for Dysthymia and the Semi-Structured Interview for the Diagnostic Criteria for Psychosomatic Research) are presented here. Well-Being Therapy, a psychotherapeutic strategy specifically aimed at pursuing euthymia, relies on self-observation of well-being episodes using a structured diary as a distinct therapeutic ingredient. The clinical science of euthymia may unravel innovative approaches to assessment and treatment of psychiatric and medical disorders, according to a unitary conceptual framework.

Anticipatory regulation of cardiovascular system on the emergence of auditory-motor interaction in young infants

Humans develop auditory-motor interaction to produce a variety of rhythmic sounds using body movements, which are often produced and amplified with tools, such as drumming. The extended production of sounds allows us to express a wide range of emotions, accompanied by physiological changes. According to previous studies, even young infants enhance movements in response to auditory feedback. However, their exhibition of physiological adaptation on the emergence of auditory-motor interaction is unclear. We investigated the movement and cardiac changes associated with auditory feedback to spontaneous limb movements in 3-month-old infants. The results showed that infants increased the frequency of limb movements inducing auditory feedback, while they exhibited a more regular rhythm of the limb movements. Furthermore, heart rate increase associated with the limb movement was first inhibited immediately after the timing of the auditory feedback, which may reflect sustained attention to the auditory stimuli. Then, through auditory-motor experience, the heart rate increase was inhibited even prior to the auditory feedback, leading to suppression of the peak intensity of the heart rate increase. These findings suggest that young infants regulate the cardiovascular system as well as limb movements in anticipation of the auditory feedback. The anticipatory regulation associated with movement and attentional changes may contribute to reduced cardiovascular stress in auditory-motor interaction, and provide a developmental basis for more sophisticated goal-directed behavior of producing rhythmic sounds.

I overthink-Therefore I am not: An active inference account of altered sense of self and agency in depersonalisation disorder

This paper considers the phenomenology of depersonalisation disorder, in relation to predictive processing and its associated pathophysiology. To do this, we first establish a few mechanistic tenets of predictive processing that are necessary to talk about phenomenal transparency, mental action, and self as subject. We briefly review the important role of 'predicting precision' and how this affords mental action and the loss of phenomenal transparency. We then turn to sensory attenuation and the phenomenal consequences of (pathophysiological) failures to attenuate or modulate sensory precision. We then consider this failure in the context of depersonalisation disorder. The key idea here is that depersonalisation disorder reflects the remarkable capacity to explain perceptual engagement with the world via the hypothesis that "I am an embodied perceiver, but I am not in control of my perception". We suggest that individuals with depersonalisation may believe that 'another agent' is controlling their thoughts, perceptions or actions, while maintaining full insight that the 'other agent' is 'me' (the self). Finally, we rehearse the predictions of this formal analysis, with a special focus on the psychophysical and physiological abnormalities that may underwrite the phenomenology of depersonalisation.

Self-Concern Across Scales: A Biologically Inspired Direction for Embodied Artificial Intelligence

Intelligence in current AI research is measured according to designer-assigned tasks that lack any relevance for an agent itself. As such, tasks and their evaluation reveal a lot more about our intelligence than the possible intelligence of agents that we design and evaluate. As a possible first step in remedying this, this article introduces the notion of “self-concern,” a property of a complex system that describes its tendency to bring about states that are compatible with its continued self-maintenance. Self-concern, as argued, is the foundation of the kind of basic intelligence found across all biological systems, because it reflects any such system's existential task of continued viability. This article aims to cautiously progress a few steps closer to a better understanding of some necessary organisational conditions that are central to self-concern in biological systems. By emulating these conditions in embodied AI, perhaps something like genuine self-concern can be implemented in machines, bringing AI one step closer to its original goal of emulating human-like intelligence.

The impaired healing hypothesis: a mechanism by which psychosocial stress and personal characteristics increase MSD risk?

While the effects of physical risk factors on MSD development have been a primary focus of musculoskeletal research, psychological stressors, and certain personal characteristics (e.g. ageing, sex, and obesity) are also associated with increased MSD risk. The psychological and personal characteristics listed above share a common characteristic: all are associated with disruption of the body's neuroendocrine and immune responses resulting in an impaired healing process. An impaired healing response may result in reduced fatigue life of musculoskeletal tissues due to a diminished ability to keep pace with accumulating damage (perhaps reparable under normal circumstances), and an increased vulnerability of damaged tissue to further trauma owing to the prolonged healing process. Research in engineered self-healing materials suggests that decreased healing kinetics in the presence of mechanical loading can substantially reduce the fatigue life of materials. A model of factors influencing damage accrual and healing will be presented. Practitioner summary: This article provides a potential reason why musculoskeletal disorder risk is affected by psychosocial stress, age, sex, and obesity. The reason is that these factors are all associated with a slower than normal healing response. This may lead to faster damage development in musculoskeletal tissues resulting in higher MSD risk.

Oscillatory entrainment to our early social or physical environment and the emergence of volitional control

An individual's early interactions with their environment are thought to be largely passive; through the early years, the capacity for volitional control develops. Here, we consider: how is the emergence of volitional control characterised by changes in the entrainment observed between internal activity (behaviour, physiology and brain activity) and the sights and sounds in our everyday environment (physical and social)? We differentiate between contingent responsiveness (entrainment driven by evoked responses to external events) and oscillatory entrainment (driven by internal oscillators becoming temporally aligned with external oscillators). We conclude that ample evidence suggests that children show behavioural, physiological and neural entrainment to their physical and social environment, irrespective of volitional attention control; however, evidence for oscillatory entrainment beyond contingent responsiveness is currently lacking. Evidence for how oscillatory entrainment changes over developmental time is also lacking. Finally, we suggest a mechanism through which periodic environmental rhythms might facilitate both sensory processing and the development of volitional control even in the absence of oscillatory entrainment.

A Bioinformatics-Assisted Review on Iron Metabolism and Immune System to Identify Potential Biomarkers of Exercise Stress-Induced Immunosuppression

The immune function is closely related to iron (Fe) homeostasis and allostasis. The aim of this bioinformatics-assisted review was twofold; (i) to update the current knowledge of Fe metabolism and its relationship to the immune system, and (ii) to perform a prediction analysis of regulatory network hubs that might serve as potential biomarkers during stress-induced immunosuppression. Several literature and bioinformatics databases/repositories were utilized to review Fe metabolism and complement the molecular description of prioritized proteins. The Search Tool for the Retrieval of Interacting Genes (STRING) was used to build a protein-protein interactions network for subsequent network topology analysis. Importantly, Fe is a sensitive double-edged sword where two extremes of its nutritional status may have harmful effects on innate and adaptive immunity. We identified clearly connected important hubs that belong to two clusters: (i) presentation of peptide antigens to the immune system with the involvement of redox reactions of Fe, heme, and Fe trafficking/transport; and (ii) ubiquitination, endocytosis, and degradation processes of proteins related to Fe metabolism in immune cells (e.g., macrophages). The identified potential biomarkers were in agreement with the current experimental evidence, are included in several immunological/biomarkers databases, and/or are emerging genetic markers for different stressful conditions. Although further validation is warranted, this hybrid method (human-machine collaboration) to extract meaningful biological applications using available data in literature and bioinformatics tools should be highlighted.

A neurobiological perspective on social influence: Serotonin and social adaptation

Humans are inherently social beings. Being suggestible to each other's expectations enables pro-social skills that are crucial for social learning and adaptation. Despite its high relevance for psychiatry, the neurobiological mechanisms underlying social adaptation are still not well understood. This review therefore provides a conceptual framework covering various distinct mechanisms underlying social adaptation and explores the neuropharmacology - in particular the role of the serotonin (5-HT) system - modulating these mechanisms. This article therefore reviews empirical results on social influence processing and reconciles them with recent findings from psychedelic research on social processing to elucidate neurobiological and neuropharmacological underpinnings of social adaptation. Various computational, neurobiological, and neurochemical processes are involved in distinct mechanisms underlying social adaptation such as the multisensory process of social information integration that is crucial for the forming of self-representation and representations of social norms. This is again associated with self- and other-perception during social interactions as well as value-based decision making that guides our behaviour in daily interactions. We highlight the critical role of 5-HT in these processes and suggest that 5-HT can facilitate social learning and may represent an important target for treating psychiatric disorders characterized by impairments in social functioning. This framework also has important implications for psychedelic-assisted therapy as well as for the development of novel treatment approaches and future research directions.

Towards better hypothesis tests in oxytocin research: Evaluating the validity of auxiliary assumptions

Various factors have been attributed to the inconsistent reproducibility of human oxytocin research in the cognitive and behavioral sciences. These factors include small sample sizes, a lack of pre-registered studies, and the absence of overarching theoretical frameworks that can account for oxytocin's effects over a broad range of contexts. While there have been efforts to remedy these issues, there has been very little systematic scrutiny of the role of auxiliary assumptions, which are claims that are not central for testing a hypothesis but nonetheless critical for testing theories. For instance, the hypothesis that oxytocin increases the salience of social cues is predicated on the assumption that intranasally administered oxytocin increases oxytocin levels in the brain. Without robust auxiliary assumptions, it is unclear whether a hypothesis testing failure is due to an incorrect hypothesis or poorly supported auxiliary assumptions. Consequently, poorly supported auxiliary assumptions can be blamed for hypothesis failure, thereby safeguarding theories from falsification. In this article, I will evaluate the body of evidence for key auxiliary assumptions in human behavioral oxytocin research in terms of theory, experimental design, and statistical inference, and highlight assumptions that require stronger evidence. Strong auxiliary assumptions will leave hypotheses vulnerable for falsification, which will improve hypothesis testing and consequently advance our understanding of oxytocin's role in cognition and behavior.

Functional assessment of bidirectional cortical and peripheral neural control on heartbeat dynamics: a brain-heart study on thermal stress

The study of functional brain-heart interplay (BHI) from non-invasive recordings has gained much interest in recent years. Previous endeavors aimed at understanding how the two dynamical systems exchange information, providing novel holistic biomarkers and important insights on essential cognitive aspects and neural system functioning. However, the interplay between cardiac sympathovagal and cortical oscillations still has much room for further investigation. In this study, we introduce a new computational framework for a functional BHI assessment, namely the Sympatho-Vagal Synthetic Data Generation Model, combining cortical (electroencephalography, EEG) and peripheral (cardiac sympathovagal) neural dynamics. The causal, bidirectional neural control on heartbeat dynamics was quantified on data gathered from 26 human volunteers undergoing a cold-pressor test. Results show that thermal stress induces heart-to-brain functional interplay sustained by EEG oscillations in the delta and gamma bands, primarily originating from sympathetic activity, whereas brain-to-heart interplay originates over central brain regions through sympathovagal control. The proposed methodology provides a viable computational tool for the functional assessment of the causal interplay between cortical and cardiac neural control.

Action Understanding Promoted by Interoception in Children: A Developmental Model

Action understanding of children develops from simple associative learning to mentalizing. With the rise of embodied cognition, the role of interoception in action observation and action understanding has received more attention. From a developmental perspective, this study proposes a novel developmental model that explores how interoception promotes action understanding of children across ages. In early infancy, most actions observed in infants come from interactions with their caregivers. Babies learn about action effects through automatic interoceptive processing and interoceptive feedback. Interoception in early infancy is not fully developed, such as the not fully developed gastrointestinal tract and intestinal nervous system. Therefore, in early infancy, action understanding is based on low-level and original interoceptive information. At this stage, after observing the actions of others, infants can create mental representations or even imitate actions without external visual feedback, which requires interoception to provide internal reference information. By early childhood, children begin to infer action intentions of other people by integrating various types of information to reach the mentalizing level. Interoception processing requires the integration of multiple internal signals, which promotes the information integration ability of children. Interoception also provides inner information for reasoning about action intention. This review also discussed the neural mechanisms of interoception and possible ways by which it could promote action understanding of children. In early infancy, the central autonomic neural network (CAN) automatically processes and responds to the actions of caregivers on infants, providing interoceptive information for action understanding of infants. In infancy, the growth of the somatomotor system provides important internal reference information for observing and imitating the actions of infants. In early childhood, the development of interoception of children facilitates the integration of internal and external information, which promotes the mentalization of action understanding of children. According to the proposed developmental model of action understanding of children promoted by interoception, there are multilevel and stage-dependent characteristics that impact the role of interoception in action understanding of children.

At the heart of the interoception network: Influence of the parasubthalamic nucleus on autonomic functions and motivated behaviors

The parasubthalamic nucleus (PSTN), a small nucleus located on the lateral edge of the posterior hypothalamus, has emerged in recent years as a highly interconnected node within the network of brain regions sensing and regulating autonomic function and homeostatic needs. Furthermore, the strong integration of the PSTN with extended amygdala circuits makes it ideally positioned to serve as an interface between interoception and emotions. While PSTN neurons are mostly glutamatergic, some of them also express neuropeptides that have been associated with stress-related affective and motivational dysfunction, including substance P, corticotropin-releasing factor, and pituitary adenylate-cyclase activating polypeptide. PSTN neurons respond to food ingestion and anorectic signals, as well as to arousing and distressing stimuli. Functional manipulation of defined pathways demonstrated that the PSTN serves as a central hub in multiple physiologically relevant networks and is notably implicated in appetite suppression, conditioned taste aversion, place avoidance, impulsive action, and fear-induced thermoregulation. We also discuss the putative role of the PSTN in interoceptive dysfunction and negative urgency. This review aims to synthesize the burgeoning preclinical literature dedicated to the PSTN and to stimulate interest in further investigating its influence on physiology and behavior.

The evolution of brain architectures for predictive coding and active inference

This article considers the evolution of brain architectures for predictive processing. We argue that brain mechanisms for predictive perception and action are not late evolutionary additions of advanced creatures like us. Rather, they emerged gradually from simpler predictive loops (e.g. autonomic and motor reflexes) that were a legacy from our earlier evolutionary ancestors-and were key to solving their fundamental problems of adaptive regulation. We characterize simpler-to-more-complex brains formally, in terms of generative models that include predictive loops of increasing hierarchical breadth and depth. These may start from a simple homeostatic motif and be elaborated during evolution in four main ways: these include the multimodal expansion of predictive control into an allostatic loop; its duplication to form multiple sensorimotor loops that expand an animal's behavioural repertoire; and the gradual endowment of generative models with hierarchical depth (to deal with aspects of the world that unfold at different spatial scales) and temporal depth (to select plans in a future-oriented manner). In turn, these elaborations underwrite the solution to biological regulation problems faced by increasingly sophisticated animals. Our proposal aligns neuroscientific theorising-about predictive processing-with evolutionary and comparative data on brain architectures in different animal species. This article is part of the theme issue 'Systems neuroscience through the lens of evolutionary theory'.

Scaffolding layered control architectures through constraint closure: insights into brain evolution and development

The functional organization of the mammalian brain can be considered to form a layered control architecture, but how this complex system has emerged through evolution and is constructed during development remains a puzzle. Here we consider brain organization through the framework of constraint closure, viewed as a general characteristic of living systems, that they are composed of multiple sub-systems that constrain each other at different timescales. We do so by developing a new formalism for constraint closure, inspired by a previous model showing how within-lifetime dynamics can constrain between-lifetime dynamics, and we demonstrate how this interaction can be generalized to multi-layered systems. Through this model, we consider brain organization in the context of two major examples of constraint closure-physiological regulation and visual orienting. Our analysis draws attention to the capacity of layered brain architectures to scaffold themselves across multiple timescales, including the ability of cortical processes to constrain the evolution of sub-cortical processes, and of the latter to constrain the space in which cortical systems self-organize and refine themselves. This article is part of the theme issue 'Systems neuroscience through the lens of evolutionary theory'.

H2O2/Ca2+/Zn2+ Complex Can Be Considered a “Collaborative Sensor” of the Mitochondrial Capacity?

In order to maintain a state of well-being, the cell needs a functional control center that allows it to respond to changes in the internal and surrounding environments and, at the same time, carry out the necessary metabolic functions. In this review, we identify the mitochondrion as such an “agora”, in which three main messengers are able to collaborate and activate adaptive response mechanisms. Such response generators, which we have identified as H₂O₂, Ca²⁺, and Zn²⁺, are capable of “reading” the environment and talking to each other in cooperation with the mitochondrion. In this manner, these messengers exchange information and generate a holistic response of the whole cell, dependent on its functional state. In this review, to corroborate this claim, we analyzed the role these actors, which in the review we call “sensors”, play in the regulation of skeletal muscle contractile capacities chosen as a model of crosstalk between Ca²⁺, Zn²⁺, and H₂O₂.