Cardiogenic control of affective behavioural state

Exploring virtual reality as an anxiety-inducing paradigm: Multimodal insights from subjective, behavioral and neurophysiological measures

Anxiety results from the complex interplay between innate defensive responses to perceived threats and higher-order cognitive processes, mediated by specialized circuits in the human neocortex. Traditional methods of anxiety induction often fail to replicate the inherent unpredictability of threats or maintain ecological validity, thereby limiting their ability to fully elucidate the underlying mechanisms of anxiety. To overcome these limitations, this study aimed to explore the effectiveness of virtual reality (VR) as an innovative anxiety-inducing tool. By further using its ability to simulate real world scenes, the neural activities inducing anxiety in VR scenes were studied. VR is used to induce anxiety through customized scenarios, while a range of data, including subjective self-reports, objective performance measures, eye movement data, and EEG signals, are collected. The findings indicate that VR is efficacious in induced anxiety, which manifests through the arousal of anxious emotions, alterations in cognitive processes, and distinct neurophysiological patterns, particularly increased theta and alpha activity in the frontal and parietal regions. This research reinforces the ecological validity of VR as a research tool, contributing to a deeper understanding of the neurophysiological basis of anxiety and providing a more nuanced framework for both anxiety research and interventions in real-world contexts.

Neural Mechanisms in Cardiovascular Health and Disease

Although the neurocardiac axis is central to cardiovascular homeostasis, its dysregulation drives heart failure and cardiometabolic diseases. This review examines the bidirectional interplay between the autonomic nervous system and the heart, highlighting the role of this interplay in disease progression and its therapeutic potential. The autonomic nervous system modulates cardiac function and vascular tone through its sympathetic and parasympathetic branches. However, in heart failure, chronic sympathetic overdrive and parasympathetic withdrawal exacerbate myocardial remodeling and metabolic dysfunction, both of which are exacerbated by cardiometabolic conditions such as obesity and diabetes. These conditions are increasingly recognized to impair neurocardiac regulation, thereby promoting inflammation and adverse outcomes. An important emerging area concerns neuroimmune control, in which the brain orchestrates systemic inflammation through circuits involving the bone marrow, spleen, and other organs, thereby amplifying cardiovascular damage. This neuroimmune axis integrates peripheral signals to influence immune responses that contribute to disease progression. Lifestyle factors, such as stress, sleep, exercise, and diet, affect autonomic and immune balance and, thus, cardiovascular disease. Therapeutically, targeting neurocardiac and neuroimmune pathways pharmacologically or via neuromodulation (eg, vagal or splenic nerve stimulation) offers promise although the clinical translation of the latter remains challenging. In this review, we synthesize preclinical and clinical data to highlight the neurocardiac axis as a critical nexus in heart failure and cardiometabolic disease. Harnessing neuroimmune and neurocardiac interactions may inform precision approaches to reduce the burden of these conditions.

The evolving neurobiology of early-life stress

Because early-life stress is common and constitutes a strong risk factor for cognitive and mental health disorders, it has been the focus of a multitude of studies in humans and experimental models. Yet, we have an incomplete understanding of what is perceived as stressful by the developing brain, what aspects of stress influence brain maturation, what developmental ages are particularly vulnerable to stress, which molecules mediate the effects of stress on brain operations, and how transient stressful experiences can lead to enduring emotional and cognitive dysfunctions. Here, we discuss these themes, highlight the challenges and progress in resolving them, and propose new concepts and avenues for future research.

Machine Learning-Enabled Emotion Recognition by Multisource Throat Signals

Emotion monitoring plays a crucial role in mental health management. However, traditional methods of emotion recognition predominantly rely on subjective questionnaires or facial expression analyses, which are often inadequate for continuous and highly accurate monitoring. In this study, we propose a high-precision, fine-grained emotion recognition system based on multisource throat physiological signals. The system collects signals through optimized flexible multiporous skin sensors and analyzes them using machine learning models capable of efficiently capturing complex feature interactions. First, we adopt a two-step cross-linking strategy to modulate the porous structure of the sensitive layer to enable accurate detection of the diverse and weak physiological signals in the throat. By extracting four-dimensional features from the input of 7025 samples, the platform based on the Light Gradient Boosting Machine (LightGBM) efficiently captures their nonlinear interactions, ultimately achieving precise classification of five emotional states (relaxation, surprise, disgust, fear, and neutral) with an accuracy of 98.9%. Further validation on an independent data set reveals an average emotion recognition accuracy of 99.3%, demonstrating the system's robustness and reliability in real-world applications. This work provides a viable technological solution for real-time and continuous emotion monitoring, offering significant potential in mental health management and related fields.

Accessing the viscera: Technologies for interoception research

Interoception, or the perception and regulation of body signals by the central nervous system, is critical for maintaining homeostasis and coordination of behaviors. Deciphering the mechanisms of interoception requires identifying pathways and decoding of diverse signals across the brain-body axis. These studies are enabled by tools to modulate and record physiological processes in the brain and visceral organs. While numerous advanced neurotechnologies are well-established in the brain, these techniques often offer limited utility for other organs, such as the gastrointestinal tract, heart, liver, or bladder. In this review, we highlight recent advances in technologies for recording and modulation of visceral organ physiology in small animals in vivo, with a focus on implantable bioelectronic organ interfaces that can be deployed in behaving animals. We discuss how such interfaces are made possible through innovations in materials and electronics and outline unmet technological challenges in interoception research.

Association between individual differences in interoception and cardiac coherence during heart rate variability biofeedback

Heart rate variability biofeedback (HRVBF) is the training to increase vagally-mediated heart rate variability (vmHRV), accompanied by slow-paced breathing and feedback of heart rhythm. It has been reported to be effective for emotion and cognition. In recent years, increased attention has turned toward participant characteristics as factors affecting HRVBF training effects. Focusing on neural basis commonalities between the mechanisms of HRVBF training effects and processing interoception, this study comprehensively measured interoception and examined the relationship between interoception and cardiac coherence reflecting HRVBF effects. Fifty-four healthy young participants were recruited, and subjective interoception was measured using the Japanese version of Multidimensional Assessment of Interoceptive Awareness (MAIA-J) and the Japanese version of the Body Perception Questionnaire-Body Awareness Very Short Form (BPQ-BAVSF-J), objective interoception using heartbeat counting task (HCT), heart rate variability (HRV), visual exteroception, and the coherence score achieved by HRVBF. We conducted a multiple regression analysis with interoception, HRV, and visual exteroception parameters as explanatory variables and the coherence score as the objective variable. Some subjective interoception and HRV parameters were found to be associated with the coherence score. Our results were consistent with previous studies, showing that higher vmHRV was related to high cardiac coherence. Interoception effects on cardiac coherence may be limited because of the low adjusted coefficient of determination and less selected explanatory variables in the multiple regression analysis. Our results may contribute toward predicting HRVBF training effects and the screening of those who are likely to benefit from the training from the perspective of interoception and vmHRV.

Interoceptive modulation of emotions

The metaphorical use of the heart to represent emotions has been documented since our earliest known writings, which reflects a historical recognition of the deep connection between bodily sensations and emotions. However, it remains an active topic of investigation to determine the degree to which bodily physiology modulates emotion states. Recent advances in the neuroscience of interoception-the process by which we sense, interpret, and integrate internal bodily signals and physiology-are uncovering neurobiological mechanisms by which visceral signals can influence emotions. Here we review interoceptive pathways that relay visceral signals to the brain and discuss how these signals influence emotion states as well as challenges and opportunities to better understand interoceptive modulation of emotions.

Association of spatiotemporal interaction of gamma oscillations with heart rate variability during response inhibition processing in patients with major depressive disorder: An MEG study

BACKGROUND

Impairment in response inhibition function is highly prevalent in patients with major depressive disorder (MDD), yet the spatiotemporal neural activity underlying response inhibition and its relationship with the autonomic nervous system (ANS) remains unclear.

METHODS

35 MDD participants and 35 healthy controls (HC) were included with magnetoencephalography (MEG) and electrocardiogram (ECG) data collecting during a go/no-go task. Heart rate variability (HRV) indices were calculated from the ECG data. Differences in functional connectivity (FC) of gamma oscillations (60-90 Hz) between 0-200 ms, 200-400 ms, and 400-600 ms in the two groups after no-go stimuli were analyzed, and the correlation between FC and HRV indices was examined.

RESULTS

The MDD group exhibited poorer task performance and lower HRV indices than the HC group. During the 200-400 ms period, compared to the HC group, the MDD group exhibited decreased FC between the left inferior frontal gyrus (opercular part) and right temporal pole (middle temporal gyrus) (t = 3.62, p < 0.05), and increased FC between the right superior frontal gyrus (orbital part) and right superior occipital gyrus (t = 3.68, p < 0.05). Additionally, a significant positive correlation was found between FC of the left inferior frontal gyrus (opercular part) and right middle temporal gyrus (temporal pole) and the HRV index RMSSD in the MDD group (r = 0.491, p < 0.05).

CONCLUSION

Abnormal spatiotemporal interactions in gamma oscillations related to response inhibition are observed in MDD patients and abnormal gamma oscillations showed task-dependent covariation with ANS indices, suggesting their potential interplay in MDD pathophysiology.

Antianxiety effects of dexmedetomidine: systematic review and meta-analysis

BACKGROUND

Despite numerous studies of the anxiolytic effects of dexmedetomidine compared with those of other drugs or saline, the results have been inconsistent. Here we report a systematic review and meta-analysis to comprehensively evaluate the evidence of the anxiolytic effects of dexmedetomidine.

METHODS

This research has been registered in the International Prospective Register of Systematic Reviews. The PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov database were searched for clinical trials that compared the anxiolytic effects of dexmedetomidine with those of a control group with valid anxiety scores from inception to December 29, 2024.

RESULTS

Overall, this systematic review and meta-analysis included 25 clinical studies with 2159 participants who underwent surgery. The primary outcome revealed that patients who were treated with dexmedetomidine had significantly lower anxiety scores than others did overall (MD = - 1.73, 95% CI = [ - 2.33, - 1.13], p < 0.00001, I2 = 86.5%). Dexmedetomidine was found to be more effective than benzodiazepines in relieving anxiety (MD = - 1.34, 95% CI = [ - 2.08, - 0.60], p = 0.0004, I2 = 83.3%). The secondary outcomes revealed no significant differences in satisfaction, pain level, sedation scores or the risk of postoperative nausea and vomiting between patients who were treated with dexmedetomidine and controls. However, the occurrence of bradycardia was more common in the dexmedetomidine groups.

CONCLUSIONS

Overall, this meta-analysis provided evidence of the potential of dexmedetomidine for relieving anxiety among patients who undergo surgery, with superior antianxiety effects compared with those of benzodiazepines.

From bugs to brain: unravelling the GABA signalling networks in the brain-gut-microbiome axis

Convergent data across species paint a compelling picture of the critical role of the gut and its resident microbiota in several brain functions and disorders. The chemicals mediating communication along these sophisticated highways of the brain-gut-microbiome (BGM) axis include both microbiota metabolites and classical neurotransmitters. Amongst the latter, GABA is fundamental to brain function, mediating most neuronal inhibition. Until recently, GABA's role and specific molecular targets in the periphery within the BGM axis had received limited attention. Yet, GABA is produced by neuronal and non-neuronal elements of the BGM, and recently, GABA-modulating bacteria have been identified as key players in GABAergic gut systems, indicating that GABA-mediated signalling is likely to transcend physiological boundaries and species. We review the available evidence to better understand how GABA facilitates the integration of molecularly and functionally disparate systems to bring about overall homeostasis and how GABA perturbations within the BGM axis can give rise to multi-system medical disorders, thereby magnifying the disease burden and the challenges for patient care. Analysis of transcriptomic databases revealed significant overlaps between GABAAR subunits expressed in the human brain and gut. However, in the gut, there are notable expression profiles for a select number of subunits that have received limited attention to date but could be functionally relevant for BGM axis homeostasis. GABAergic signalling, via different receptor subtypes, directly regulates BGM homeostasis by modulating the excitability of neurons within brain centres responsible for gastrointestinal (GI) function in a sex-dependent manner, potentially revealing mechanisms underlying the greater prevalence of GI disturbances in females. Apart from such top-down regulation of the BGM axis, a diverse group of cell types, including enteric neurons, glia, enteroendocrine cells, immune cells and bacteria, integrate peripheral GABA signals to influence brain functions and potentially contribute to brain disorders. We propose several priorities for this field, including the exploitation of available technologies to functionally dissect components of these GABA pathways within the BGM, with a focus on GI and brain-behaviour-disease. Furthermore, in silico ligand-receptor docking analyses using relevant bacterial metabolomic datasets, coupled with advances in knowledge of GABAAR 3D structures, could uncover new ligands with novel therapeutic potential. Finally, targeted design of dietary interventions is imperative to advancing their therapeutic potential to support GABA homeostasis across the BGM axis.

A top-down insular cortex circuit crucial for non-nociceptive fear learning

Understanding how threats drive fear memory formation is crucial to understanding how organisms adapt to environments and treat threat-related disorders such as PTSD. While traditional Pavlovian conditioning studies have provided valuable insights, the exclusive reliance on electric shock as a threat stimulus has limited our understanding of diverse threats. To address this, we developed a conditioning paradigm using a looming visual stimulus as an unconditioned stimulus (US) in mice and identified a distinct neural circuit for visual threat conditioning. Parabrachial CGRP neurons were necessary for both conditioning and memory retrieval. Upstream neurons in the posterior insular cortex (pIC) responded to looming stimuli, and their projections to the parabrachial nucleus (PBN) induced aversive states and drove conditioning. However, this pIC-to-PBN pathway was not required for foot-shock conditioning. These findings reveal how non-nociceptive visual stimuli can drive aversive states and fear memory formation, expanding our understanding of aversive US processing beyond traditional models.

Redefining respiratory sinus arrhythmia as respiratory heart rate variability: an international Expert Recommendation for terminological clarity

The variation of heart rate in phase with breathing, known as 'respiratory sinus arrhythmia' (RSA), is a physiological phenomenon present in all air-breathing vertebrates. RSA arises from the interaction of several physiological mechanisms but is primarily mediated by rhythmic changes in cardiac parasympathetic (vagal) activity, increasing heart rate during inspiration and decreasing heart rate during expiration. RSA amplitude is an indicator of autonomic and cardiac health; RSA is diminished or absent in common pathological conditions such as chronic heart failure and hypertension. In this Expert Recommendation, we argue that the term 'RSA', although historically important, is semantically inaccurate and carries misleading pathological connotations, contributing to misunderstanding and misinterpretation of the origin and the physiological importance of the phenomenon. We propose replacing 'RSA' with the term 'respiratory heart rate variability' (RespHRV), which avoids pathological connotations and emphasizes the specific respiratory contribution to heart rate variability. We clarify that RespHRV encompasses respiratory-related heart rate variations in both the low-frequency and high-frequency bands traditionally defined in heart rate variability analysis, and that its amplitude should not be misconstrued as a measure of vagal tone. Adopting the proposed term 'RespHRV' is expected to unify understanding and stimulate further experimental and clinical research into the physiological mechanisms and functional importance of this phenomenon.

Novel insights into rural spatial design: A bio-behavioral study employing eye-tracking and electrocardiography measures

In order to objectively assess the effectiveness of rural space design on the affective dimension, this study utilized eye-tracking and electrocardiogram (ECG) monitoring techniques to quantify users' visual attention and emotional responses and to assess the impact of rural design on users' affective experience. The results show that incorporating natural elements and cultural features into the design enhances the values of the subjects' pupil diameter change rate, Heart Rate Variability Index (HRV), subjective evaluation and reduces their Saccade Velocity Average. The experimental results not only verify the application value of eye tracking and ECG monitoring techniques in assessing the design effect of rural space, but also provide a scientific assessment method based on the user's physiological and emotional responses, thus providing a strong support for the optimization of rural space design.

Regulation of Cardiac Function by the Autonomic Nervous System

The autonomic nervous system is critical for regulating cardiovascular physiology. The neurocardiac axis encompasses multiple levels of control, including the motor circuits of the sympathetic and parasympathetic nervous systems, sensory neurons that contribute to cardiac reflexes, and the intrinsic cardiac nervous system that provides localized sensing and regulation of the heart. Disruption of these systems can lead to significant clinical conditions. Recent advances have enhanced our understanding of the autonomic control of the heart, detailing the specific neuronal populations involved and their physiologic roles. In this review, we discuss this research at each level of the neurocardiac axis. We conclude by discussing the clinical field of neurocardiology and attempts to translate this new understanding of neurocardiac physiology to the clinic. We highlight the contributions of autonomic dysfunction in prevalent cardiovascular diseases and assess the current status of novel neuroscience-based treatment approaches.

Cold memories control whole-body thermoregulatory responses

Environmental thermal challenges trigger the brain to coordinate both autonomic and behavioural responses to maintain optimal body temperature1-4. It is unknown how temperature information is precisely stored and retrieved in the brain and how it is converted into a physiological response. Here we investigated whether memories could control whole-body metabolism by training mice to remember a thermal challenge. Mice were conditioned to associate a context with a specific temperature by combining thermoregulatory Pavlovian conditioning with engram-labelling technology, optogenetics and chemogenetics. We report that if mice are returned to an environment in which they previously experienced a 4 °C cold challenge, they increase their metabolic rates regardless of the actual environmental temperature. Furthermore, we show that mice have increased hypothalamic activity when they are exposed to the cold, and that a specific network emerges between the hippocampus and the hypothalamus during the recall of a cold memory. Both natural retrieval and artificial reactivation of cold-sensitive memory engrams in the hippocampus mimic the physiological responses that are seen during a cold challenge. These ensembles are necessary for cold-memory retrieval. These findings show that retrieval of a cold memory causes whole-body autonomic and behavioural responses that enable mice to maintain thermal homeostasis.

From Physiology to Psychiatry: Key role of vagal interoceptive pathways in emotional control

Interoception is the awareness of bodily sensations, conveyed by both hormonal and neural signals. The vagus nerve is the primary neural interoceptive conduit, responsible for transmitting information from peripheral organs to the brain. It is widely accepted that vagal signals are essential for purely physiological functions like blood pressure maintenance, or nutrient intake homeostasis. However, a growing body of evidence, taking advantage of new technological advances, suggests that the vagus nerve also orchestrates or tunes emotions. Disruption of vagal interoceptive feedback prevents normal emotional control in rodents. Importantly, accumulating evidence indicates that pathological disruption of vagal afferent signals also occurs in humans and may constitute an important risk factor for emotional disorders. Hence, alleviating vagal interoceptive deficits may constitute a new therapeutic avenue for neurotic and affective disorders. Considering the technical and safety challenges for direct stimulation of brain regions relevant to emotionality disorders, the vagus nerve offers a safer and more practical route of potentially achieving similar outcomes. Here we will highlight the earliest studies which examined the consequences of manipulations of the vagal afferent neurons on anxiety, fear, and mood, and integrate these older findings with new research investigating the necessity of vagal afferent neurons in mediating the anxiety or mood-altering effects of physiological signals. We will also discuss the evolutionary significance of vagal control over emotional states within the boundaries of "normal" physiology and conclude by discussing the challenges of engaging the vagal interoception as novel therapeutics in mental health disorders.

Abscisic Acid Rescues Behavior in Adult Female Mice in Attention Deficit Disorder with Hyperactivity Model of Dopamine Depletion by Regulating Microglia and Increasing Vesicular GABA Transporter Expression

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental syndrome typically diagnosed in childhood that may persist into adulthood. Its etiology encompasses both genetic and environmental factors, with genetic studies indicating catecholamine dysfunction and epidemiological evidence emphasizing neuroinflammation as a potential trigger. To investigate the roles of inflammation and development processes in ADHD, we conducted a longitudinal behavioral study using female Swiss mice with a dopamine deficit model. We explored the impact of neonatal dopaminergic lesions, treatment with abscisic acid (ABA)-an anti-inflammatory hormone-and developmental changes by comparing behavioral patterns in juvenile and adult mice. Postmortem analyses assessed neuroinflammation through microglial morphology, NLRP3, cytokine expression, and the excitatory/inhibitory (E/I) ratio in specific brain regions. Neonatal dopaminergic lesions induced hyperactivity and hypersensitivity in juvenile mice that persisted into adulthood. In adults, increased social interaction and memory impairment were observed in lesioned mice. Brain development mitigated impulsivity, while ABA treatment reduced locomotor activity, downregulated pain sensitivity, and influenced social interaction, although it did not completely resolve cognitive deficits in lesioned adult mice. In brain regions such as the anterior cingulate cortex (ACC), posterior insular cortex (pIC), and hippocampus, lesions significantly altered microglial morphology. In the ACC, lesions increased IL-1β and TNFα levels, decreased Arg1 mRNA levels, and disrupted the E/I balance. Importantly, ABA treatment restored microglial morphology, normalized IL-1β and Arg1 expression and upregulated vGAT levels. This study demonstrates that dopamine deficits lead to microglia alterations and E/I imbalance, contributing to ADHD symptoms. While some symptoms improve with brain development, targeting microglial health in specific brain regions emerges as a promising therapeutic approach for managing ADHD.

Heart rate changes related to risky selections and outcomes in rat gambling tasks

Risk-taking behavior is crucial to increase potential outcomes and alter arousal states in the brain and body represented by heart rates. In this study, we monitored changes in heart rate as rats performed a 50:50 gambling task in which they selected either a certain outcome with 100 % probability (sure option) or a double outcome with 50 % probability (risky option). When rats selected risky options, they exhibited significantly greater decreases in their heart rates before selection than when they selected certain options. In addition, we observed significantly larger increases in heart rates when the rats recognized larger outcomes after selecting the risky options than the sure options. Similar dynamic changes in heart rates were observed in a 25:75 gambling condition with different reward magnitudes and probabilities. These results demonstrate that animals can dynamically alter their heart rates in response to risky selection and outcomes.

Rough is salient: a conserved vocal niche to hijack the brain's salience system

The propensity to communicate extreme emotional states and arousal through salient, non-referential vocalizations is ubiquitous among mammals and beyond. Screams, whether intended to warn conspecifics or deter aggressors, require a rapid increase of air influx through vocal folds to induce nonlinear distortions of the signal. These distortions contain salient, temporally patterned acoustic features in a restricted range of the audible spectrum. These features may have a biological significance, triggering fast behavioural responses in the receivers. We present converging neurophysiological and behavioural evidence from humans and animals supporting that the properties emerging from nonlinear vocal phenomena are ideally adapted to induce efficient sensory, emotional and behavioural responses. We argue that these fast temporal-rough-modulations are unlikely to be an epiphenomenon of vocal production but rather the result of selective evolutionary pressure on vocal warning signals to promote efficient communication. In this view, rough features may have been selected and conserved as an acoustic trait to recruit ancestral sensory salience pathways and elicit optimal reactions in the receiver. By exploring the impact of rough vocalizations at the receiver's end, we review the perceptual, behavioural and neural factors that may have shaped these signals to evolve as powerful communication tools.This article is part of the theme issue 'Nonlinear phenomena in vertebrate vocalizations: mechanisms and communicative functions'.

A neural mechanism for learning from delayed postingestive feedback

Animals learn the value of foods on the basis of their postingestive effects and thereby develop aversions to foods that are toxic1-10 and preferences to those that are nutritious11-13. However, it remains unclear how the brain is able to assign credit to flavours experienced during a meal with postingestive feedback signals that can arise after a substantial delay. Here we reveal an unexpected role for the postingestive reactivation of neural flavour representations in this temporal credit-assignment process. To begin, we leverage the fact that mice learn to associate novel14,15, but not familiar, flavours with delayed gastrointestinal malaise signals to investigate how the brain represents flavours that support aversive postingestive learning. Analyses of brain-wide activation patterns reveal that a network of amygdala regions is unique in being preferentially activated by novel flavours across every stage of learning (consumption, delayed malaise and memory retrieval). By combining high-density recordings in the amygdala with optogenetic stimulation of malaise-coding hindbrain neurons, we show that delayed malaise signals selectively reactivate flavour representations in the amygdala from a recent meal. The degree of malaise-driven reactivation of individual neurons predicts the strengthening of flavour responses upon memory retrieval, which in turn leads to stabilization of the population-level representation of the recently consumed flavour. By contrast, flavour representations in the amygdala degrade in the absence of unexpected postingestive consequences. Thus, we demonstrate that postingestive reactivation and plasticity of neural flavour representations may support learning from delayed feedback.

Manipulation of interoceptive signaling biases decision making in rhesus macaques

Several influential theories have proposed that interoceptive signals, sent from the body to the brain, contribute to neural processes that coordinate complex behaviors. We altered the physiological state of the body using compounds that have minimal effect on the brain and evaluated their effect on decision making in rhesus monkeys. We used glycopyrrolate, a nonspecific muscarinic (parasympathetic) antagonist, and isoproterenol, a beta-1/2 (sympathetic) agonist, to create a sympathetic-dominated state in the periphery, that was indexed by increased heart rate. Rhesus monkeys were trained on two variants of an approach-avoidance conflict task. The tasks offered a choice between enduring mildly aversive stimuli in exchange for a steady flow of rewards, or canceling the aversive stimuli, forgoing the rewards. The latency to interrupt the aversive stimuli was used as a measure of monkeys' tolerance for contact with a hot but not painful stimulus or airflow directed at their muzzle. Both drugs reduced tolerance for the aversive stimuli. To determine whether the drug-induced autonomic state reduced the subjective value of the reward, we tested the effects of glycopyrrolate on a food preference task. Food preference was unaltered, suggesting that the sympathetic dominated state in the periphery selectively reduces tolerance for aversive stimuli without altering reward-seeking behaviors. As the drugs used are expected to have little or no direct effect on the brain, the observed biases in decision making are likely induced by interoceptive afferents that signal to the brain the physiological state of the body.

Distinction in the function and microstructure of white matter between major depressive disorder and generalized anxiety disorder

BACKGROUND

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are two of the leading causes of impairment to human mental health. These two psychiatric disorders overlap in many symptoms and neurobiological features thus difficult to distinguish in some cases.

METHODS

We enrolled 102 participants, comprising 40 patients with MDD, 32 patients with GAD and 30 matched healthy controls (HCs), to undergo multimodal magnetic resonance imaging (MRI) scans. We identified 18 major white matter (WM) tracts with automated fiber quantification (AFQ) method, to evaluated microstructure with fractional anisotropy (FA) and function with amplitude of low-frequency fluctuation (ALFF). An analysis of variance (ANOVA) was employed to identify differences among groups. We further explored the correlations of FA and ALFF features with clinical symptoms.

RESULTS

We identified the white matter microstructure and function of 89 participants. ANOVA and post-hoc analysis revealed that GAD group exhibited significantly higher FA of right anterior thalamic radiation (ATR) than in MDD and HC groups. Additionally, MDD group exhibited significantly decreased ALFF in forceps major (FMA), forceps minor (FMI), bilateral corticospinal tracts (CST) and left inferior fronto-occipital fasciculus (IFOF) compared to both GAD and HC group. ALFF of right CST was significantly negatively correlated to HAMA and a moderate effect size and marginal significance was found between FA of the right ATR and HAMA in GAD group.

LIMITATIONS

This study used cross-sectional data and sample size was small.

CONCLUSION

Tracking microstructure and function of WM with AFQ method has the potential to distinguish different psychiatric diseases.

Targeting the central and peripheral nervous system to regulate bone homeostasis: mechanisms and potential therapies

The skeleton is innervated by different types of nerves and receives signaling from the nervous system to maintain homeostasis and facilitate regeneration or repair. Although the role of peripheral nerves and signals in regulating bone homeostasis has been extensively investigated, the intimate relationship between the central nervous system and bone remains less understood, yet it has emerged as a hot topic in the bone field. In this review, we discussed clinical observations and animal studies that elucidate the connection between the nervous system and bone metabolism, either intact or after injury. First, we explored mechanistic studies linking specific brain nuclei with bone homeostasis, including the ventromedial hypothalamus, arcuate nucleus, paraventricular hypothalamic nucleus, amygdala, and locus coeruleus. We then focused on the characteristics of bone innervation and nerve subtypes, such as sensory, sympathetic, and parasympathetic nerves. Moreover, we summarized the molecular features and regulatory functions of these nerves. Finally, we included available translational approaches that utilize nerve function to improve bone homeostasis and promote bone regeneration. Therefore, considering the nervous system within the context of neuromusculoskeletal interactions can deepen our understanding of skeletal homeostasis and repair process, ultimately benefiting future clinical translation.

Projection-targeted photopharmacology reveals distinct anxiolytic roles for presynaptic mGluR2 in prefrontal- and insula-amygdala synapses

Dissecting how membrane receptors regulate neural circuits is critical for deciphering principles of neuromodulation and mechanisms of drug action. Here, we use a battery of optical approaches to determine how presynaptic metabotropic glutamate receptor 2 (mGluR2) in the basolateral amygdala (BLA) controls anxiety-related behavior in mice. Using projection-specific photopharmacological activation, we find that mGluR2-mediated presynaptic inhibition of ventromedial prefrontal cortex (vmPFC)-BLA, but not posterior insular cortex (pIC)-BLA, connections produces a long-lasting decrease in spatial avoidance. In contrast, presynaptic inhibition of pIC-BLA connections decreases social avoidance and novelty-induced hypophagia without impairing working memory, establishing this projection as a novel target for the treatment of anxiety disorders. Fiber photometry and viral mapping reveal distinct activity patterns and anatomical organization of vmPFC-BLA and pIC-BLA circuits. Together, this work reveals new aspects of BLA neuromodulation with therapeutic implications while establishing a powerful approach for optical mapping of drug action.

Theoretical analysis of low-power deep synergistic sono-optogenetic excitation of neurons by co-expressing light-sensitive and mechano-sensitive ion-channels

The present challenge in neuroscience is to non-invasively exercise low-power and high-fidelity control of neurons situated deep inside the brain. Although, two-photon optogenetic excitation can activate neurons to millimeter depth with sub-cellular specificity and millisecond temporal resolution, it can also cause heating of the targeted tissue. On the other hand, sonogenetics can non-invasively modulate the cellular activity of neurons expressed with mechano-sensitive proteins in deeper areas of the brain with less spatial selectivity. We present a theoretical analysis of a synergistic sono-optogenetic method to overcome these limitations by co-expressing a mechano-sensitive (MscL-I92L) ion-channel with a light-sensitive (CoChR/ChroME2s/ChRmine) ion-channel in hippocampal neurons. It is shown that in the presence of low-amplitude subthreshold ultrasound pulses, the two-photon excitation threshold for neural spiking reduces drastically by 73% with MscL-I92L-CoChR (0.021 mW/µm2), 66% with MscL-I92L-ChroME2s (0.029 mW/µm2), and 64% with MscL-I92L-ChRmine (0.013 mW/µm2) at 5 Hz. It allows deeper excitation of up to 1.2 cm with MscL-I92L-ChRmine combination. The method is useful to design new experiments for low-power deep excitation of neurons and multimodal neuroprosthetic devices and circuits.

The Power of Exercise: Unlocking the Biological Mysteries of Peripheral-Central Crosstalk in Parkinson's Disease

BACKGROUND

Exercise is a widely recognized non-pharmacological treatment for Parkinson's Disease (PD). The bidirectional regulation between the brain and peripheral organs has emerged as a promising area of research, with the mechanisms by which exercise impacts PD closely linked to the interplay between peripheral signals and the central nervous system.

AIM OF REVIEW

This review aims to summarize the mechanisms by which exercise influences peripheral-central crosstalk to improve PD, discuss the molecular processes mediating these interactions, elucidate the pathways through which exercise may modulate PD pathophysiology, and identify directions for future research.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review examines how exercise-induced cytokine release promotes neuroprotection in PD. It discusses how exercise can stimulate cytokine secretion through various pathways, including the gut-brain, muscle-brain, liver-brain, adipose-brain, and bone-brain axes, thereby alleviating PD symptoms. Additionally, the potential contributions of the heart-brain, lung-brain, and spleen-brain axes, as well as multi-axis crosstalk-such as the brain-gut-muscle and brain-gut-bone axes-are explored in the context of exercise therapy. The study highlights the need for further research into peripheral-central crosstalk and outlines future directions to address challenges in clinical PD therapy.

The brain-heart axis: integrative cooperation of neural, mechanical and biochemical pathways

The neural and cardiovascular systems are pivotal in regulating human physiological, cognitive and emotional states, constantly interacting through anatomical and functional connections referred to as the brain-heart axis. When this axis is dysfunctional, neurological conditions can lead to cardiovascular disorders and, conversely, cardiovascular dysfunction can substantially affect brain health. However, the mechanisms and fundamental physiological components of the brain-heart axis remain largely unknown. In this Review, we elucidate these components and identify three primary pathways: neural, mechanical and biochemical. The neural pathway involves the interaction between the autonomic nervous system and the central autonomic network in the brain. The mechanical pathway involves mechanoreceptors, particularly those expressing mechanosensitive Piezo protein channels, which relay crucial information about blood pressure through peripheral and cerebrovascular connections. The biochemical pathway comprises many endogenous compounds that are important mediators of neural and cardiovascular function. This multisystem perspective calls for the development of integrative approaches, leading to new clinical specialties in neurocardiology.

A deep learning pipeline for three-dimensional brain-wide mapping of local neuronal ensembles in teravoxel light-sheet microscopy

Teravoxel-scale, cellular-resolution images of cleared rodent brains acquired with light-sheet fluorescence microscopy have transformed the way we study the brain. Realizing the potential of this technology requires computational pipelines that generalize across experimental protocols and map neuronal activity at the laminar and subpopulation-specific levels, beyond atlas-defined regions. Here, we present artficial intelligence-based cartography of ensembles (ACE), an end-to-end pipeline that employs three-dimensional deep learning segmentation models and advanced cluster-wise statistical algorithms, to enable unbiased mapping of local neuronal activity and connectivity. Validation against state-of-the-art segmentation and detection methods on unseen datasets demonstrated ACE's high generalizability and performance. Applying ACE in two distinct neurobiological contexts, we discovered subregional effects missed by existing atlas-based analyses and showcase ACE's ability to reveal localized or laminar neuronal activity brain-wide. Our open-source pipeline enables whole-brain mapping of neuronal ensembles at a high level of precision across a wide range of neuroscientific applications.

Validation of two enzyme immunoassays for non-invasive glucocorticoid measurement in a lacertid lizard (Podarcis muralis): Effects of pharmacological and biological stimuli on faecal corticosterone metabolites and behaviour

The assessment of stress-related hormone levels using non-invasive methods has gained popularity in mammal and bird welfare, yet its application in reptiles remains limited. Particularly, the exploration of physiological measures such as faecal corticosterone metabolites (FCMs) for reptilian welfare has scarcely been explored. This study aims to validate two enzyme immunoassays (5α-pregnane-3ß,11ß,21-triol-20-one and 11-oxoaetiocholanolone EIA) for monitoring FCM levels in the European common wall lizard (Podarcis muralis). We collected daily faecal samples before (baseline) and after (post-treatment phase) inducing elevated corticosterone levels using transdermal administration of corticosterone (pharmacological treatment) and handling/confinement (biological treatment). We also conducted daily behavioural observations to explore the relationship between stress-related corticosterone changes and behaviour. Although treatments induced significant increases in FCM levels, the effect was much larger in the pharmacological one. Transdermal corticosterone induced a cumulative increase in FCMs over the treatment period, with a higher response observed in females. In contrast, the biological treatment yielded smaller FCM peaks, with no significant sex differences. Overall, 5α-pregnane-3ß,11ß,21-triol-20-one EIA appeared to be more sensitive in detecting these effects. Regarding lizard behaviour, both treatments led to increased hiding and decreased basking compared to baseline. The effects were more pronounced in animals subjected to handling/confinement, despite smaller FCM increases. Our results confirm the suitability of an EIA for monitoring FCMs in both male and female common wall lizards and provide insights into the complexities of using integrated approaches to assess stress, highlighting the need for further research on direct measures to evaluate reptile welfare.

The brain's action-mode network

The brain is always intrinsically active, using energy at high rates while cycling through global functional modes. Awake brain modes are tied to corresponding behavioural states. During goal-directed behaviour, the brain enters an action-mode of function. In the action-mode, arousal is heightened, attention is focused externally and action plans are created, converted to goal-directed movements and continuously updated on the basis of relevant feedback, such as pain. Here, we synthesize classical and recent human and animal evidence that the action-mode of the brain is created and maintained by an action-mode network (AMN), which we had previously identified and named the cingulo-opercular network on the basis of its anatomy. We discuss how rather than continuing to name this network anatomically, annotating it functionally as controlling the action-mode of the brain increases its distinctiveness from spatially adjacent networks and accounts for the large variety of the associated functions of an AMN, such as increasing arousal, processing of instructional cues, task general initiation transients, sustained goal maintenance, action planning, sympathetic drive for controlling physiology and internal organs (connectivity to adrenal medulla), and action-relevant bottom-up signals such as physical pain, errors and viscerosensation. In the functional mode continuum of the awake brain, the AMN-generated action-mode sits opposite the default-mode for self-referential, emotional and memory processing, with the default-mode network and AMN counterbalancing each other as yin and yang.

Neural circuits and therapeutic mechanisms of empathic pain

Empathy is the capacity to understand and share the experiences of others. This ability fosters connections between individuals, enriching the fabric of our shared world. One notable example is empathy for the pain of others. Such experiences facilitate the identification of potential dangers, both for oneself and for others. Neuroimaging studies have helped to pinpoint brain regions that modulate empathic pain. Recently, there has also been a surge in studies exploring the neural mechanisms of empathic pain in rodent models. Neuropsychiatric disorders such as autism, psychosis, and schizophrenia often exhibit empathy deficits. Targeting the modulation of empathic pain holds potential for alleviating core symptoms in these patients. Interestingly, empathy research may also benefit pain management, leading to new approaches for understanding the negative emotions associated with pain. This review summarizes recent advances in neuroimaging for the study of empathic pain, outlines the underlying neurocircuit mechanisms, describes therapeutic strategies, and explores promising avenues for future research. This article is part of the Special Issue on "Empathic Pain".

Vagal nerve stimulation dynamically alters anxiety-like behavior in rats

BACKGROUND

Electrical vagal nerve stimulation (VNS), at currents designed to target sensory, interoceptive neurons, decreases anxiety-like behavior.

OBJECTIVE/HYPOTHESIS

We hypothesized that different VNS current intensities would differentially alter anxiety-like behavior through the activation of distinct brainstem circuits.

METHODS

Electrodes were implanted to stimulate the left vagus nerve and to record diaphragm muscle and electrocardiogram activity. The VNS current required to elicit the A-fiber-mediated Hering-Breuer Reflex (HBR) was determined for each animal. Based on this threshold, animals received either sham stimulation or VNS at 1.5 (mid-intensity VNS) or 3 (higher-intensity VNS) times the threshold for HBR activation. Anxiety-like behavior was assessed using the elevated plus maze, open field test, and novelty-suppressed feeding test. Additionally, a place preference assay determined whether VNS is rewarding or aversive. Finally, a c-Fos assay was performed to evaluate VNS-driven neuronal activation within the brainstem.

RESULTS

Mid-intensity VNS reduced anxiety-like behavior in the elevated plus maze and open field test. Higher-intensity VNS was aversive during the place preference assay, confounding anxiety measures. Both intensities increased overall c-Fos expression in neurons within the nucleus of the solitary tract, but mid-intensity VNS specifically increased c-Fos expression in noradrenergic neurons within the nucleus of the solitary tract while decreasing it in the locus coeruleus. In contrast, higher-intensity VNS had no effect on c-Fos expression in noradrenergic neurons of either the nucleus of the solitary tract or locus coeruleus.

CONCLUSION

Delivery of VNS induced reproducible, current intensity-dependent, effects on anxiety-like and aversive behavior in rats.

[The joint analysis of heart health and mental health based on continual learning]

Cardiovascular diseases and psychological disorders represent two major threats to human physical and mental health. Research on electrocardiogram (ECG) signals offers valuable opportunities to address these issues. However, existing methods are constrained by limitations in understanding ECG features and transferring knowledge across tasks. To address these challenges, this study developed a multi-resolution feature encoding network based on residual networks, which effectively extracted local morphological features and global rhythm features of ECG signals, thereby enhancing feature representation. Furthermore, a model compression-based continual learning method was proposed, enabling the structured transfer of knowledge from simpler tasks to more complex ones, resulting in improved performance in downstream tasks. The multi-resolution learning model demonstrated superior or comparable performance to state-of-the-art algorithms across five datasets, including tasks such as ECG QRS complex detection, arrhythmia classification, and emotion classification. The continual learning method achieved significant improvements over conventional training approaches in cross-domain, cross-task, and incremental data scenarios. These results highlight the potential of the proposed method for effective cross-task knowledge transfer in ECG analysis and offer a new perspective for multi-task learning using ECG signals.

A stochastic model for affect dynamics: methodological insights from heart rate variability in an illustrative case of Anorexia Nervosa

Background

Affect dynamics, or variations in emotional experiences over time, are linked to psychological health and well-being, with moderate emotional variations indicating good psychophysical health. Given the impact of emotional state on cardiac variability, our objective was to develop a quantitative method to measure affect dynamics for better understanding emotion temporal management in Anorexia Nervosa (AN).

Methods

The study proposed an experimental and methodological approach to evaluate physiological affect dynamics in clinical settings. It tested affective transitions and temporal changes using emotional images from the International Affective Picture System (IAPS), examining physiological characteristics of a patient with AN. The methodology involved calculating a heart rate variability index, e.g., RMSSD, and using it in a Discrete Time and Discrete Space Markov chain to define, quantify, and predict emotional fluctuations over time.

Results

The patient with Anorexia Nervosa showed a high likelihood of transitioning from positive to negative emotional states, particularly at lower arousal levels. The steady state matrix indicated a tendency to remain in highly activated pleasant states, reflecting difficulties in maintaining emotional balance.

Conclusions

Employing Markov chains provided a quantitative and insightful approach for examining affect dynamics in a patient with AN. This methodology accurately measures emotional transitions and provides a clear and interpretable framework for clinicians and patients. By leveraging Markovian indexes, mental health professionals may gain a comprehensive understanding of emotional fluctuations' patterns. Moreover, graphical representations of emotional transitions may enhance the clinician-patient dialogue, facilitating a clearer emotional and physiological profile for the implementation of personalized treatment procedures.

Modelling the time-resolved modulations of cardiac activity in rats: A study on pharmacological autonomic stimulation

Assessing cardiac dynamics over time is essential for understanding cardiovascular health and its parallel patterns of activity with the brain. We present a methodology to estimate the time-resolved sympathetic and parasympathetic modulations of cardiac dynamics, specifically tailored for the rat heart. To evaluate the performance of our method, we study a dataset comprising spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. These rats were administered dobutamine to elicit autonomic dynamics. The results obtained from our method demonstrated accurate time-resolved depiction of sympathetic reactivity induced by dobutamine administration. These responses closely resembled the expected autonomic alterations observed during physical exercise conditions, albeit emulated pharmacologically. We further compared our method with standard measures of low-frequency (LF) and high-frequency (HF) components, which are commonly used, although debated, for sympathetic and parasympathetic activity estimation. The comparisons with LF and HF measures further confirmed the effectiveness of our method in better capturing autonomic changes in rat cardiac dynamics. Our findings highlight the potential of our adapted method for time-resolved analysis in future clinical and translational studies involving rodent models. The validation of our approach in animal models opens new avenues for investigating the relationship between ongoing changes in cardiac activity and parallel changes in brain dynamics. Such investigations are crucial for advancing our understanding of the brain-heart connection, particularly in cases involving neurodegeneration, brain injuries and cardiovascular conditions. KEY POINTS: We developed a method for time-resolved estimation of sympathetic and parasympathetic modulations in rat cardiac dynamics, validated against standard low-frequency and high-frequency measures. We used a cohort of spontaneously hypertensive rats and Wistar-Kyoto rats, with dobutamine administration to induce autonomic responses. Our method accurately depicted time-resolved sympathetic reactivity similar to autonomic changes during physical exercise. Our findings suggest potential for future clinical and translational studies on the brain-heart connection, particularly in cardiovascular conditions.

Effect of exogenous manipulation of glucocorticoid concentrations on meerkat heart rate, behaviour and vocal production

Encoding of emotional arousal in vocalisations is commonly observed in the animal kingdom, and provides a rapid means of information transfer about an individual's affective responses to internal and external stimuli. As a result, assessing affective arousal-related variation in the acoustic structure of vocalisations can provide insight into how animals perceive both internal and external stimuli, and how this is, in turn, communicated to con- or heterospecifics. However, the underlying physiological mechanisms driving arousal-related acoustic variation remains unclear. One potential driver of such variation in behaviour and vocal production are glucocorticoids. Through exogenous glucocorticoid manipulation, we aimed to gain insight on the relationship between arousal and physiological parameters, behaviour and vocal production in wild meerkats (Suricata suricatta). To this aim, we administered glucocorticoids to wild meerkats, and recorded their heart rate, vigilance behaviour, call rate and acoustic structure during natural behavioural contexts. The results suggest that, although the glucocorticoid treatment did increase plasma glucocorticoid levels, this did not result in observable changes in heart rate, vigilance, or vocal production. This lack of treatment effect suggests that, while glucocorticoids may be a significant component and correlate of the arousal response, they are not the direct drivers of affective arousal related changes in heart rate, behaviour, or vocal production.

The neuroimmune connectome in health and disease

The nervous and immune systems have complementary roles in the adaptation of organisms to environmental changes. However, the mechanisms that mediate cross-talk between the nervous and immune systems, called neuroimmune interactions, are poorly understood. In this Review, we summarize advances in the understanding of neuroimmune communication, with a principal focus on the central nervous system (CNS): its response to immune signals and the immunological consequences of CNS activity. We highlight these themes primarily as they relate to neurological diseases, the control of immunity, and the regulation of complex behaviours. We also consider the importance and challenges linked to the study of the neuroimmune connectome, which is defined as the totality of neuroimmune interactions in the body, because this provides a conceptual framework to identify mechanisms of disease pathogenesis and therapeutic approaches. Finally, we discuss how the latest techniques can advance our understanding of the neuroimmune connectome, and highlight the outstanding questions in the field.

Mechanosensation of the heart and gut elicits hypometabolism and vigilance in mice

Interoception broadly refers to awareness of one's internal milieu. Although the importance of the body-to-brain communication that underlies interoception is implicit, the vagal afferent signalling and corresponding brain circuits that shape perception of the viscera are not entirely clear. Here, we use mice to parse neural circuits subserving interoception of the heart and gut. We determine that vagal sensory neurons expressing the oxytocin receptor (Oxtr), referred to as NGOxtr, send projections to cardiovascular or gastrointestinal tissues and exhibit molecular and structural features indicative of mechanosensation. Chemogenetic excitation of NGOxtr decreases food and water consumption, and remarkably, produces a torpor-like phenotype characterized by reductions in cardiac output, body temperature and energy expenditure. Chemogenetic excitation of NGOxtr also creates patterns of brain activity associated with augmented hypothalamic-pituitary-adrenal axis activity and behavioural indices of vigilance. Recurrent excitation of NGOxtr suppresses food intake and lowers body mass, indicating that mechanosensation of the heart and gut can exert enduring effects on energy balance. These findings suggest that the sensation of vascular stretch and gastrointestinal distention may have profound effects on whole-body metabolism and, possibly, mental health.

Heart-derived factors and organ cross-talk in settings of health and disease: new knowledge and clinical opportunities for multimorbidity

Cardiovascular disease affects millions of people worldwide and often presents with other conditions including metabolic, renal and neurological disorders. A variety of secreted factors from multiple organs/tissues (proteins, nucleic acids and lipids) have been implicated in facilitating organ cross-talk that may contribute to the development of multimorbidity. Secreted proteins have received the most attention, with the greatest body of research related to factors released from adipose tissue (adipokines), followed by skeletal muscle (myokines). To date, there have been fewer studies on proteins released from the heart (cardiokines) implicated with organ cross-talk. Early evidence for the secretion of cardiac-specific factors facilitating organ cross-talk came in the form of natriuretic peptides which are secreted via the classical endoplasmic reticulum-Golgi pathway. More recently, studies in cardiomyocyte-specific genetic mouse models have revealed cardiac-initiated organ cross-talk. Cardiomyocyte-specific modulation of microRNAs (miR-208a and miR-23-27-24 cluster) and proteins such as the mediator complex subunit 13 (MED13), G-protein-coupled receptor kinase 2 (GRK2), mutant α-myosin heavy-chain (αMHC), ubiquitin-like modifier-activating enzyme (ATG7), oestrogen receptor alpha (ERα) and fibroblast growth factor 21 (FGF21) have resulted in metabolic and renal phenotypes. These studies have implicated a variety of factors which can be secreted via the classical pathway or via non-classical mechanisms including the release of extracellular vesicles. Cross-talk between the heart and the brain has also been described (e.g. via miR-1 and an emerging concept, interoception: detection of internal neural signals). Here we summarize these studies taking into consideration that factors may be secreted in both settings of health and in disease.

Coordinated excitatory and inhibitory circuits governing unpredictable threat-induced anxiety

Anxiety is elicited by excessive apprehension about unpredictable threats. However, the neural circuit governing unpredictable threat induced anxiety remains unclear. Here, we found ventral bed nucleus of the stria terminalis (vBNST) GABAergic neurons displayed selective activation to unpredictable threats through coordinated excitatory input from insular cortex glutamergic neurons and inhibitory input from the lateral nucleus of the amygdala (CeL) somatostatin neurons. Using activity-dependent neuronal tagging technology, we found that unpredictable threat responsive cells in vBNST drive freezing and anxiety via projections to ventral lateral periaqueductal gray (vlPAG) and median nucleus of the amygdala, respectively. Finally, we identified that potassium voltage-gated channel subfamily Q member 3 (KCNQ3) plays an essential role in hyperactivity of vBNST GABAergic neurons induced anxiety. These data revealed a forward inhibitory circuit that determines the selective activation of vBNST in unpredictable threat and anxiety, and suggest that the KCNQ3 channel is a promising target for the treatment of anxiety disorders after unpredictable stress.

Digital phenotyping from wearables using AI characterizes psychiatric disorders and identifies genetic associations

Psychiatric disorders are influenced by genetic and environmental factors. However, their study is hindered by limitations on precisely characterizing human behavior. New technologies such as wearable sensors show promise in surmounting these limitations in that they measure heterogeneous behavior in a quantitative and unbiased fashion. Here, we analyze wearable and genetic data from the Adolescent Brain Cognitive Development (ABCD) study. Leveraging >250 wearable-derived features as digital phenotypes, we show that an interpretable AI framework can objectively classify adolescents with psychiatric disorders more accurately than previously possible. To relate digital phenotypes to the underlying genetics, we show how they can be employed in univariate and multivariate genome-wide association studies (GWASs). Doing so, we identify 16 significant genetic loci and 37 psychiatric-associated genes, including ELFN1 and ADORA3, demonstrating that continuous, wearable-derived features give greater detection power than traditional case-control GWASs. Overall, we show how wearable technology can help uncover new linkages between behavior and genetics.

Common threads: Altered interoceptive processes across affective and anxiety disorders

There is growing attention towards atypical brain-body interactions and interoceptive processes and their potential role in psychiatric conditions, including affective and anxiety disorders. This paper aims to synthesize recent developments in this field. We present emerging explanatory models and focus on brain-body coupling and modulations of the underlying neurocircuitry that support the concept of a continuum of affective disorders. Grounded in theoretical frameworks like peripheral theories of emotion and predictive processing, we propose that altered interoceptive processes might represent transdiagnostic mechanisms that confer common vulnerability traits across multiple disorders. A deeper understanding of the interplay between bodily states and neural processing is essential for a holistic conceptualization of mental disorders.

How the brain impacts the heart: lessons from ischaemic stroke and other neurological disorders

Cardiovascular alterations are common in patients who had ischaemic stroke, haemorrhagic stroke and other acute brain disorders such as seizures. These cardiac complications are important drivers of morbidity and mortality and comprise blood-based detection of cardiomyocyte damage, ECG changes, heart failure and arrhythmia. Recently, the concept of a distinct 'stroke-heart syndrome' has been formulated as a pathophysiological framework for poststroke cardiac complications. The concept considers cardiac sequelae after stroke to be the result of a stroke-induced disturbance of the brain-heart axis. In this review, we describe the spectrum of cardiac changes secondary to ischaemic stroke and other acute brain disorders. Furthermore, we focus on Takotsubo syndrome secondary to acute brain disorders as a model disease of disturbed brain-heart interaction. Finally, we aim to provide an overview of the anatomical and functional links between the brain and the heart, with emphasis on the autonomic network and the role of inflammation. Given the clinical relevance of the deleterious impact of acute brain injury on the heart, we call for clinical awareness and for starting joint efforts combining expertise of neurology and cardiology to identify specific therapeutic interventions.

The neurobiology of parenting and infant-evoked aggression

Parenting behavior comprises a variety of adult-infant and adult-adult interactions across multiple timescales. The state transition from nonparent to parent requires an extensive reorganization of individual priorities and physiology and is facilitated by combinatorial hormone action on specific cell types that are integrated throughout interconnected and brainwide neuronal circuits. In this review, we take a comprehensive approach to integrate historical and current literature on each of these topics across multiple species, with a focus on rodents. New and emerging molecular, circuit-based, and computational technologies have recently been used to address outstanding gaps in our current framework of knowledge on infant-directed behavior. This work is raising fundamental questions about the interplay between instinctive and learned components of parenting and the mutual regulation of affiliative versus agonistic infant-directed behaviors in health and disease. Whenever possible, we point to how these technologies have helped gain novel insights and opened new avenues of research into the neurobiology of parenting. We hope this review will serve as an introduction for those new to the field, a comprehensive resource for those already studying parenting, and a guidepost for designing future studies.

Real-life Affective Forecasting in Young Adults with High Social Anhedonia: An Experience Sampling Study

Background and hypothesis

Affective forecasting (AF), the ability to forecast emotional responses for future events, is critical for optimal decision-making and mental health. Most previous AF studies were conducted using laboratory-based tasks but overlooked the impacts of real-life situations and social interactions. This study used the experience sampling method to examine real-life AF in young healthy adults and individuals with high social anhedonia.

Study design

In Study 1, 109 young healthy adults reported anticipated and experienced emotions of personal events for 30 days on mobile phones. In Study 2, we examined real-life AF in 28 individuals with high social anhedonia (HSA) and 32 individuals with low social anhedonia (LSA).

Study results

In Study 1 (totaling 8031 real-life events), participants anticipated and experienced social events as more positive and more arousing than non-social events, but also with larger AF discrepancy. In Study 2 (totaling 2066 real-life events), compared with the LSA group, the HSA group anticipated less pleasure and displayed a larger valence discrepancy especially for social but not for non-social events. However, the HSA group reported less experienced pleasure for both social and non-social events.

Conclusions

Using an ecological method for assessing real-life AF, we extended the previous laboratory-based findings to real-life situations. These findings demonstrate the effects of sociality on real-life AF and elucidate the deficit in anticipating social pleasure among HSA individuals, which reflects liability to schizophrenia-spectrum disorders. Altered AF may be a potential intervention target in people with schizophrenia spectrum disorder.

Interoceptive Mechanisms and Emotional Processing

Interoception, the sensing of internal bodily signals, is intricately linked with the experience of emotions. Various theoretical models of emotion incorporate aspects of interoception as a fundamental component alongside higher-order processes such as the appraisal of internal signals guided by external context. Interoception can be delineated into different dimensions, which include the nature of afferent signals, the accuracy with which they can be sensed, their neural processing, and the higher-order interpretation of these signals. This review methodically evaluates these interoceptive dimensions through empirical research to illustrate their role in shaping emotions. Clinical and neurodevelopmental conditions characterized by altered emotional profiles, such as anxiety, depression, schizophrenia, posttraumatic stress disorder, emotionally unstable personality disorder, and autism, exhibit distinct changes in interoception. Various therapeutic approaches, including behavioral, pharmacological, and psychological strategies, may be efficacious for treating conditions associated with emotional alterations by targeting interoceptive mechanisms.

The mechanisms of electrical neuromodulation

The central and peripheral nervous systems are specialized to conduct electrical currents that underlie behaviour. When this multidimensional electrical system is disrupted by degeneration, damage, or disuse, externally applied electrical currents may act to modulate neural structures and provide therapeutic benefit. The administration of electrical stimulation can exert precise and multi-faceted effects at cellular, circuit and systems levels to restore or enhance the functionality of the central nervous system by providing an access route to target specific cells, fibres of passage, neurotransmitter systems, and/or afferent/efferent communication to enable positive changes in behaviour. Here we examine the neural mechanisms that are thought to underlie the therapeutic effects seen with current neuromodulation technologies. To gain further insights into the mechanisms associated with electrical stimulation, we summarize recent findings from genetic dissection studies conducted in animal models. KEY POINTS: Electricity is everywhere around us and is essential for how our nerves communicate within our bodies. When nerves are damaged or not working properly, using exogenous electricity can help improve their function at distinct levels - inside individual cells, within neural circuits, and across entire systems. This method can be tailored to target specific types of cells, nerve fibres, neurotransmitters and communication pathways, offering significant therapeutic potential. This overview explains how exogenous electricity affects nerve function and its potential benefits, based on research in animal studies. Understanding these effects is important because electrical neuromodulation plays a key role in medical treatments for neurological conditions.

Neuropsychiatric drug development: Perspectives on the current landscape, opportunities and potential future directions

Mental health represents a major challenge to our societies. One key difficulty associated with neuropsychiatric drug development is the lack of connection between the underlying biology and the disease. Nevertheless, there is growing optimism in this field with recent drug approvals (the first in decades) and renewed interest from pharmaceutical companies and investors. Here we review some of the most promising drug discovery and development endeavors currently deployed by industry. We also present elements illustrating the renewed interest from key stakeholders in neuropsychiatric drug development and provide potential future directions in this field.

Affective integration in experience, judgment, and decision-making

The role of affect in value-based judgment and decision-making has attracted increasing interest in recent decades. Most previous approaches neglect the temporal dependence of mental states leading to mapping a relatively well-defined, but largely static, feeling state to a behavioral tendency. In contrast, we posit that expected and experienced consequences of actions are integrated over time into a unified overall affective experience reflecting current resources under current demands. This affective integration is shaped by context and continually modulates judgments and decisions. Changes in affective states modulate evaluation of new information (affect-as-information), signal changes in the environment (affect-as-a-spotlight) and influence behavioral tendencies in relation to goals (affect-as-motivation). We advocate for an approach that integrates affective dynamics into decision-making paradigms. This dynamical account identifies the key variables explaining how changes in affect influence information processing may provide us with new insights into the role of affect in value-based judgment and decision-making.