A link between the systems: functional differentiation and integration within the human insula revealed by meta-analysis

From social effort to social behavior: An integrated neural model for social motivation

As humans rely on social groups for survival, social motivation is central to behavior and well-being. Here we define social motivation as the effort that initiates and directs behavior towards social outcomes, with the goal of satisfying our fundamental need for connection. We propose an integrated framework of social motivation which emphasizes the maintenance of optimal connection levels through effort exertion, regulating social approach and avoidance, which allow interpersonal synchrony. Together, these behaviors serve as basic building blocks of social behavior, and give rise to behaviors critical for collective living such as cooperation and empathy. We describe a neural model according to which social connection levels are monitored by the hypothalamus, while the anterior cingulate cortex and anterior insula respond to detected social deficiency. As adjustment is required, the social effort system - comprised of the thalamus and striatum - is activated. This system directs neural networks that permit interpersonal synchrony or, conversely, desynchronization, aiming to restore and maintain optimal connection by preventing isolation on the one hand, and exaggerated social closeness on the other hand. The proposed framework offers insights into disorders characterized by aberrant social motivation, potentially identifying neural dysfunctions that may inform novel interventions.

A multicenter cross-sectional study to elucidate altered resting-state functional connectivity of the insular cortex in anorexia nervosa, segmented by functional localization

Although changes in insular function have been thought to play a central role in the pathophysiology of anorexia nervosa (AN), due to factors such as insufficient sample size, there have been no studies examining changes in resting-state functional connectivity (rsFC) between insula and whole brain in AN, based on functional localization of insula. Here, we subdivided insula into 6 regions per side based on functional localization and reanalyzed previously published functional magnetic resonance imaging data from 114 female patients with AN and 135 female healthy controls (HC). We calculated the rsFCs between ROIs and compared the results between groups, with the 12 insular regions serving as seed ROIs and 142 regions of the whole brain as target ROIs. Compared to HC, AN patients had a increased rsFC between dorsal anterior insula (daIC) and amygdala, and a decreased rsFC between posterior division of dorsal middle insula (pdmIC) and opercular cortex (false discovery rate [FDR] corrected p-value < 0.05 with analysis-level correction, which means that FDR correction was applied to all seed ROIs and all target ROI combinations). These rsFC changes may be the neurological basis for AN symptoms, such as hypersensitivity to negative stimuli, taste disorder, and enhanced taste aversion learning.

Neural mechanisms, influencing factors and interventions in empathic pain

Empathic pain, defined as the emotional resonance with the suffering of others, is akin to the observer's own experience of pain and is vital for building and sustaining positive interpersonal relationships. Despite its importance, the neural mechanism of empathic pain remains poorly understood. In this review, we integrated and summarized the currently knowledge on the neural networks associated with empathic pain, focusing on key brain regions such as the insula, anterior cingulate cortex (ACC), ventral tegmental area (VTA), nucleus accumbens (NAc), and locus coeruleus (LC)/norepinephrine (NE)-sympatho-adrenomedullar (LC/NE-SAM) system. We also reviewed the factors that affect empathic pain, including gender, personal beliefs, the intimacy of relationships, and the nature of interpersonal relationships, and highlighted the central role of the insula and ACC in the neural circuitry of empathy, the importance of the IC-BLA and ACC-NAc/VTA connections in modulating empathic pain, and the involvement of the LC/NE-SAM system in mediating pain empathy. We further discussed how gender significantly influences empathic pain, with women showing more intense emotional reactions to social distress than men. It also summarized the roles of personal pain history and empathy levels in modulating empathic responses. Furthermore, the review emphasized the impact of social factors such as the nature of interpersonal relationships and experiences of social exclusion on empathic pain. By providing a detailed exploration of the neural mechanisms and influencing factors of empathic pain, this review aims to establish a robust foundation for developing targeted therapeutic strategies and improving pain management in clinical settings.

Melanin-concentrating hormone and orexin shape social affective behavior via action in the insular cortex of rat

RATIONALE

In a social context, individuals are able to detect external information from others and coordinate behavioral responses according to the situation, a phenomenon called social decision-making. Social decision-making is multifaceted, influenced by emotional and motivational factors like stress, sickness, and hunger. However, the neurobiological basis for motivational state competition and interaction is not well known.

OBJECTIVE

We investigated possible neural mechanisms through which internal states could shape social behavior in a social affective preference (SAP) test. In the SAP test, experimental rats given a choice to interact with naïve or stressed conspecifics exhibit an age-dependent preference to interact with stressed juvenile conspecifics, but avoid stressed adult conspecifics. First, we assessed the effect of food and water deprivation on SAP behavior. Behavior in the SAP test requires the insular cortex, which receives input from the ingestion-related peptides melanin-concentrating hormone (MCH) and orexin neurons of the lateral hypothalamus (LH). This study aimed to evaluate the role of LH and insular MCH and orexin in SAP test.

METHODS

SAP tests were conducted in rats that were sated, food and water deprived or allowed 1 h of access to food and water after 14 h of deprivation (relieved condition). Separate cohorts of sated rats received cannula implants for microinjection of drugs to inhibit the LH or to block or stimulate MCH or orexin receptors in the insula prior to SAP tests or social interaction tests.

RESULTS

Food and water deprivation prior to SAP tests with juvenile rats caused a shift in preference away from the stressed rat toward the naïve juveniles. Pharmacological inhibition of LH with muscimol (100 ng/side) abolished the preference for the juvenile-stressed conspecific, as well as the preference for the adult naïve conspecific. The blockade of MCH receptor 1or orexin receptors in the insular cortex with SNAP94847 (50 μM) or TCS1102 (1 μM), respectively, also abolished the preference for the stressed juvenile conspecific, but only the antagonism of orexin receptors was able to abolish the preference for the adult naïve conspecific. Microinjection of increasing doses (50 or 500 nM) of MCH or orexin-A in the insular cortex increased the interaction time in the one-on-one social interaction test with juvenile conspecifics; however, only the microinjection of orexin-A increased the interaction time with adult naïve conspecifics.

CONCLUSIONS

Taken together, these results suggest that lateral hypothalamus peptides shape the direction of social approach or avoidance via actions MCH and orexin neurotransmission in the insular cortex.

Resting-state functional connectivity changes following audio-tactile speech training

Understanding speech in background noise is a challenging task, especially when the signal is also distorted. In a series of previous studies, we have shown that comprehension can improve if, simultaneously with auditory speech, the person receives speech-extracted low-frequency signals on their fingertips. The effect increases after short audio-tactile speech training. In this study, we used resting-state functional magnetic resonance imaging (rsfMRI) to measure spontaneous low-frequency oscillations in the brain while at rest to assess training-induced changes in functional connectivity. We observed enhanced functional connectivity (FC) within a right-hemisphere cluster corresponding to the middle temporal motion area (MT), the extrastriate body area (EBA), and the lateral occipital cortex (LOC), which, before the training, was found to be more connected to the bilateral dorsal anterior insula. Furthermore, early visual areas demonstrated a switch from increased connectivity with the auditory cortex before training to increased connectivity with a sensory/multisensory association parietal hub, contralateral to the palm receiving vibrotactile inputs, after training. In addition, the right sensorimotor cortex, including finger representations, was more connected internally after the training. The results altogether can be interpreted within two main complementary frameworks. The first, speech-specific, factor relates to the pre-existing brain connectivity for audio-visual speech processing, including early visual, motion, and body regions involved in lip-reading and gesture analysis under difficult acoustic conditions, upon which the new audio-tactile speech network might be built. The other framework refers to spatial/body awareness and audio-tactile integration, both of which are necessary for performing the task, including in the revealed parietal and insular regions. It is possible that an extended training period is necessary to directly strengthen functional connections between the auditory and the sensorimotor brain regions for the utterly novel multisensory task. The results contribute to a better understanding of the largely unknown neuronal mechanisms underlying tactile speech benefits for speech comprehension and may be relevant for rehabilitation in the hearing-impaired population.

Structural and functional changes of insula subregions in migraine without aura and their relationships with pain perception

Migraine is a highly prevalent and disabling neurological disorder characterized by abnormal encoding of pain perception, linked to structural and functional abnormalities in the insula. Insular subregions play critical but distinct roles in this process, however, the specific patterns and mechanisms remain elusive in migraineurs. In this study, voxel-based morphometry and seed-based functional connectivity (FC) were employed to investigate structural and functional alterations in insula subdivisions in 44 patients with migraine without aura (MWoA) compared with 51 matched healthy controls. Pain perception was evaluated using the intensity, frequency, and duration of migraine. Compared with healthy controls, patients exhibited(1) reduced gray matter volume in the bilateral dorsal anterior insula (dAI);(2) increased FC between the dAI/posterior insula and bilateral precuneus, the left dAI and left middle temporal gyrus, the left ventral AI and superior/middle frontal gyrus;(3) decreased FC between the left dAI and left middle frontal gyrus, left middle occipital gyrus and right pallidum. Moreover, the left dAI was correlated with the duration and frequency of migraine, the right dAI was correlated with the intensity and duration of migraine. Our results provide novel evidence in support of the insula abnormality hypothesis in migraine and highlight the pivotal role of alterations in the dAI in pain perception in migraineurs.

Influence of insulin sensitivity on food cue evoked functional brain connectivity in children

OBJECTIVE

Insulin resistance during childhood is a risk factor for developing type 2 diabetes and other health problems later in life. Studies in adults have shown that insulin resistance affects regional and network activity in the brain which are vital for behavior, including ingestion and metabolic control. To date, no study has investigated how brain connections during exposure to food cues are association with peripheral insulin sensitivity in children.

METHODS

We included 53 children (36 girls) between the age of 7-11 years, who underwent an oral Glucose Tolerance Test (oGTT) to estimate peripheral insulin sensitivity (ISI). Brain responses were measured using functional magnetic resonance imaging (fMRI) before and after glucose ingestion. We compared food-cue task-based activity and functional connectivity (FC) between children with lower and higher ISI, adjusted for age and BMIz.

RESULTS

Independent of prandial state (i.e., glucose ingestion), children with lower ISI showed higher FC between the anterior insula and caudate and lower FC between the posterior insula and mid temporal cortex than children with higher ISI. Sex differences were found based on prandial state and peripheral insulin sensitivity in the insular FC. No differences were found on mean brain responses to food cues.

CONCLUSIONS

In response to food cues, children with lower peripheral insulin sensitivity exhibited distinctive patterns of neural connectivity, notably in the insula's functional connections, when contrasted with their counterparts with higher peripheral insulin sensitivity. These differences might influence eating behavior and future risk of developing diabetes.

Finding Peace in Pixels: Exploring the Therapeutic Mechanisms of Virtual Nature for Young Adults' Mental Well-Being

Background: This investigation examines the phenomenological dimensions of young adults' engagement with virtual natural environments for psychological stress amelioration through rigorous thematic analysis. Contemporary epidemiological data reveal a concerning prevalence of stress among young adults aged 18 to 29 years, with approximately 30% reporting moderate to severe manifestations. Despite virtual reality (VR)'s emergence as a promising modality for mental well-being interventions, a significant lacuna exists regarding the qualitative understanding of these immersive experiences. Methods: Through semi-structured interviews with 35 young adults following a four-week VR nature intervention, we constructed a conceptual framework comprising five interconnected strata: intervention, experience, process, context, and outcome. Results: Our analysis illuminated intricate bidirectional relationships among sensory elements, emotional responses, immersion depth, interactive affordances, post-session effects, psychological development, implementation challenges, individual variability, and comparative efficacy. The findings demonstrate congruence with both Attention Restoration Theory and Stress Recovery Theory while necessitating consideration of technology-specific mediators. Notably, the identified "stress barrier" phenomenon temporarily inhibited intrusive cognitions, suggesting promising therapeutic mechanisms. Pronounced heterogeneity in environmental preferences and psychophysiological responsiveness underscores the imperative for personalized implementation strategies. Conclusions: These insights provide substantive guidance for VR nature applications across therapeutic, occupational, and educational domains, potentially augmenting our repertoire for addressing stress-related sequelae in contemporary society.

Heterogeneity of human insular cortex: Five principles of functional organization across multiple cognitive domains

The insular cortex serves as a critical hub for human cognition, but how its anatomically distinct subregions coordinate diverse cognitive, emotional, and social functions remains unclear. Using the Human Connectome Project's multi-task fMRI dataset (N=524), we investigated how insular subregions dynamically engage during seven different cognitive tasks spanning executive function, social cognition, emotion, language, and motor control. Our findings reveal five key principles of human insular organization. First, insular subregions maintain distinct functional signatures that enable reliable differentiation based on activation and connectivity patterns across cognitive domains. Second, these subregions dynamically reconfigure their network interactions in response to specific task demands while preserving their core functional architecture. Third, clear functional specialization exists along the insula's dorsal-ventral axis: the dorsal anterior insula selectively responds to cognitive control demands through interactions with frontoparietal networks, while the ventral anterior insula preferentially processes emotional and social information via connections with limbic and default mode networks. Fourth, we observed counterintuitive connectivity patterns during demanding cognitive tasks, with the dorsal anterior insula decreasing connectivity to frontoparietal networks while increasing connectivity to default mode networks - suggesting a complex information routing mechanism rather than simple co-activation of task-relevant networks. Fifth, while a basic tripartite model captures core functional distinctions, finer-grained parcellations revealed additional cognitive domain-specific advantages that are obscured by simpler parcellation approaches. Our results illuminate how the insula's organization supports its diverse functional roles through selective engagement of distinct neural networks, providing a new framework for understanding both normal cognitive function and clinical disorders involving insular dysfunction.

Somatosensory false feedback biases emotional ratings through interoceptive embodiment

Mismatches between perceived and veridical physiological signals during false feedback (FFB) can bias emotional judgements. Paradigms using auditory FFB suggest perceived changes in heart rate (HR) increase ratings of emotional intensity irrespective of feedback type (increased or decreased HR), implicating right anterior insula as a mismatch comparator between exteroceptive and interoceptive information. However, few paradigms have examined effects of somatosensory FFB. Participants rated the emotional intensity of randomized facial expressions while they received 20 s blocks of pulsatile somatosensory stimulation at rates higher than HR, lower than HR, equivalent to HR, or no stimulation during a functional magnetic resonance neuroimaging scan. FFB exerted a bidirectional effect on reported intensity ratings of the emotional faces, increasing over the course of each 20 s stimulation block. Neuroimaging showed FFB engaging regions indicative of affective touch processing, embodiment, and reflex suppression. Contrasting higher vs. lower HR FFB revealed engagement of right insula and centres supporting socio-emotional processing. Results indicate that exposure to pulsatile somatosensory stimulation can influence emotional judgements though its progressive embodiment as a perceived interoceptive arousal state, biasing how affective salience is ascribed to external stimuli. Results are consistent with multimodal integration of priors and prediction-error signalling in shaping perceptual judgments.

Common neural correlates of chronic pain - A systematic review and meta-analysis of resting-state fMRI studies

Maladaptive brain plasticity has been reported in chronic pain (CP) conditions, though it remains unclear if there are common alterations across pathologies. Therefore, we systematically synthesized literature comparing resting-state functional magnetic resonance imaging (rs-fMRI) in CP patients and healthy controls (HC), and meta-analyzed data whenever applicable. Separate meta-analyses were performed for each method - (fractional) amplitude of low-frequency fluctuations (fALFF, ALFF), regional homogeneity (ReHo), seed-based connectivity (according to the seed) and independent component analysis (according to the network). In qualitative synthesis, sensory-discriminative pain processing - thalamus, insula, temporal and sensory cortices - and cognitive and emotional processing - cingulate, prefrontal and parietal cortices and precuneus - regions concentrated CP/HC differences. Meta-analyses revealed decreased ALFF and increased ReHo in the precuneus, increased fALFF in the left posterior insula and disrupted within- and cross-network connectivity of default mode network (DMN) nodes, as well as altered connectivity in top-down pain modulation pathways. Specifically, it showed decreased anterior and increased posterior components' representation within DMN, enhanced connectivity between the medial prefrontal cortex (mPFC, part of the DMN) and anterior insula (part of the salience network), and decreased mPFC connectivity with the periaqueductal gray matter (PAG). Collectively, results suggest that CP disrupts the natural functional organization of the brain, particularly impacting DMN nodes (mPFC and precuneus), insula and top-town pain modulation circuits.

Anatomo-functional organization of insular networks: From sensory integration to behavioral control

Classically, the insula is considered an associative multisensory cortex where emotional awareness emerges through the integration of interoceptive and exteroceptive information, along with autonomic regulation. However, since early intracortical microstimulation (ICMS) studies, the insular cortex has also been conceived as a mosaic of anatomo-functional sectors processing various types of sensory information to generate specific overt behaviors. Based on this, the insula has been subdivided into distinct functional fields: an anterior field associated with oroalimentary behaviors, a middle field involved dorsally in hand movements and ventrally in emotional reactions, and a posterior field engaged in axial and proximal movements. Nevertheless, the anatomo-functional networks through which these fields produce motor behaviors remain largely unknown. To fill this gap in the present study, we investigated the connectivity of the macaque insula using a multimodal approach which combines resting-state fMRI with data from tract-tracing injections in insular functional fields defined by ICMS, as well as in brain areas known to be connected to the insula and characterized by specific somatotopic organization. The results revealed that each insular functional field takes part in distinct somatotopically organized network modulating specific motor or visceromotor behaviors, extending previous models that subdivide the insula primarily based on the types of interoceptive and exteroceptive information it receives. Our findings posit the various insular sectors as interfaces that synthesize diverse interoceptive and exteroceptive inputs into coherent subjective experiences and decision-making processes, within an embodied and enactive framework, that moves beyond the traditional dichotomy between sensory experience and motor behavior.

Association of RDoC dimensions with post mortem brain transcriptional profiles in Alzheimer's disease

INTRODUCTION

Neuropsychiatric symptoms are common in people with Alzheimer's disease (AD) across all severity stages. Their heterogeneous presentation and variable temporal association with cognitive decline suggest shared and distinct biological mechanisms. We hypothesized that specific patterns of gene expression associate with distinct National Institute of Mental Health Research Domain Criteria (RDoC) domains in AD.

METHODS

Post-mortem bulk RNA sequencing of the insula and anterior cingulate cortex from 60 brain donors, representing the spectrum of canonical Alzheimer's disease neuropathology, was combined with natural language processing approaches based on the RDoC Clinical Domains to uncover transcriptomic patterns linked to disease progression.

RESULTS

Distinct sets of >100 genes (P false discovery rate < 0.05) were specifically associated with at least one clinical domain (cognitive, social, negative, positive, arousal). In addition, dysregulation of immune response pathways was shared across domains and brain regions.

DISCUSSION

Our findings provide evidence for distinct transcriptional profiles associated with RDoC domains suggesting that each dimension is characterized by sets of genes providing insight into the underlying mechanisms.

Highlights

Post mortem brain tissue investigations are critically important for Alzheimer's disease (AD) research.Neuropsychiatric symptoms in AD are common and an important aspect of AD.Categorical phenotypes are commonly used, but insufficiently describe the heterogenous presentation of AD.Using natural language processing (NLP) of post mortem brain donor health records provides insight into dimensional phenotypes of AD.We provide evidence for distinct RNA expression profiles associated with NLP-derived Research Domain Criteria clinical domain scores.

Regulation of craving and underlying resting-state neural circuitry predict hazard of smoking lapse

Among individuals with substance use disorders, clinical outcomes may be improved by identifying brain-behavior models that predict drug re/lapse vulnerabilities such as the ability to regulate drug cravings and inhibit drug use. In a sample of nicotine-dependent adult cigarette smokers (N = 213), this laboratory study examined associations between regulation of craving (ROC) efficacy and smoking lapse, utilized functional connectivity multivariate pattern analysis (FC-MVPA) and seed-based connectivity (SBC) analyses to identify resting-state neural circuitry underlying ROC efficacy, and then examined if the identified ROC-mediated circuitry predicted hazard of smoking lapse. Regarding behavior, worse ROC efficacy predicted a greater hazard of smoking lapse. Regarding brain and behavior, FC-MVPA identified 29 brain-wide functional clusters associated with ROC efficacy. Follow-up SBC analyses using 9 of the FC-MVPA-derived clusters identified a total of 64 resting-state edges (i.e., cluster-to-cluster connections) underlying ROC efficacy, 10 of which were also associated with the hazard of smoking lapse. ROC efficacy edges also associated with smoking lapse were largely composed of connections between frontal-striatal-limbic clusters and sensory-motor clusters and better behavioral outcomes were associated with stronger resting-state FC. Findings suggest that both ROC efficacy and underlying resting-state neural circuitry may inform prediction models of re/lapse vulnerabilities and serve as treatment targets for cessation interventions.

Alterations of Activity in Visual Areas of Left Mesial Temporal Lobe Epilepsy Patients: Evidence from Moving Facial Emotional Tasks

Background

Persons with epilepsy suffer from problems with social adaptation and face numerous social issues, even when the seizures are well-controlled. Facial emotion recognition (FER), one of the key components of social cognition, has been shown to be impaired in persons with mesial temporal lobe epilepsy (MTLE).

Objective

To clarify the impairment of neural networks in persons with MTLE, we performed functional magnetic resonance imaging (fMRI) studies of MTLE persons using six dynamic tasks involving FER.

Methods

We evaluated brain responses to realistic dynamic facial emotional expressions involving six basic emotions (fear, happiness, anger, sadness, disgust and surprise) in nine persons with left MTLE and ten healthy controls (HCs) using fMRI.

Results

We noted brain responses to facial emotions in regions related to FER, such as the anterior insular cortex, medial frontal gyrus, superior frontal gyrus and cerebellum by our moving tasks which involved video tasks used to evaluate FER. Persons with left MTLE showed a reduced response in the right calcarine cortex compared to that of HCs.

Conclusions

This is the first study to evaluate task-related fMRI on exposure to six basic emotions involving moving tasks in persons with epilepsy. FER deficit in persons with left MTLE may be partially associated with calcarine activity.

Homeostasis and dyshomeostasis in language and violent acting out. A dialogue between neuroscience and psychoanalysis

In this article we consider the question of homeostasis and memory from the perspectives of neuroscience and psychoanalysis. Our aim is to describe a link between homeostasis/dyshomeostasis, memory/language, and violent acting out. Our study is based on clinical observations concerning two groups of persons: those who were incarcerated for perpetrating non-premeditated murder and those who were victimized by violent trauma in their lives. The clinical findings, combined with the analysis of the relevant literature and research, demonstrate that the dyshomeostatic state, through a positive homeostasis, can drive the person to restore the balance by their usual coping mechanisms and thereby generate negative homeostasis. These acts-all violent, non-premeditated, and forms of desubjectivized acting out-stem from being outside language on account of two pathological extremes of memory, its absence or its excess. Aided by neuroscience and the results of our clinical findings, we support the practice of recalling and strengthening memory traces of trauma in psychotherapy.

Graded changes in local functional connectivity of the cerebral cortex in young people with depression

BACKGROUND

Major depressive disorder (MDD) is marked by significant changes to the local synchrony of spontaneous neural activity across various brain regions. However, many methods for assessing this local connectivity use fixed or arbitrary neighborhood sizes, resulting in a decreased capacity to capture smooth changes to the spatial gradient of local correlations. A newly developed method sensitive to classical anatomo-functional boundaries, Iso-Distant Average Correlation (IDAC), was therefore used to examine depression associated alterations to the local functional connectivity of the brain.

METHOD

One-hundred and forty-seven adolescents and young adults with MDD and 94 healthy controls underwent a resting-state functional magnetic resonance imaging (fMRI) scan. Whole-brain functional connectivity maps of intracortical neural activity within iso-distant local areas (5-10, 15-20, and 25-30 mm) were generated to characterize local fMRI signal similarities.

RESULTS

Across all spatial distances, MDD participants demonstrated greater local functional connectivity of the bilateral posterior hippocampus, retrosplenial cortex, dorsal insula, fusiform gyrus, and supplementary motor area. Local connectivity alterations in short and medium distances (5-10 and 15-20 mm) in the mid insula cortex were additionally associated with expressive suppression use, independent of depressive symptom severity.

CONCLUSIONS

Our study identified increased synchrony of the neural activity in several regions commonly implicated in the neurobiology of depression. These effects were relatively consistent across the three distances examined. Longitudinal investigation of this altered local connectivity will clarify whether these differences are also found in other age groups and if this relationship is modified by increased disease chronicity.

A role for the insula in establishing social dominance: structural and functional MRI studies in nonhuman primates

Awareness of one's position in the social hierarchy is essential for survival. Conversely, poor social cognition is associated with several neuropsychiatric diseases. Although brain regions that mediate understanding of the social hierarchy are poorly understood, recent evidence implicates the insula. Magnetic resonance imaging (MRI) scans were acquired in twelve individually housed male cynomolgus monkeys to determine whether structural and functional characteristics of the insular cortex predicted the social rank that monkeys would attain once they formed stable social hierarchies. Structural MRI revealed that left insular volume was significantly larger in monkeys that would become dominant vs. subordinate. No differences were observed in other areas including amygdala, caudate nucleus, or prefrontal cortex. Volumetric differences were localized to dorsal anterior regions of both left and right insulae. Functional MRI revealed that global correlation, a measure of connectedness to the rest of the brain, was significantly lower in the left insula of monkeys who would become dominant vs. subordinate. Moreover, the fractional amplitude of low-frequency fluctuations, a reflection of spontaneous brain activity, trended lower in bilateral insula in the future dominant monkeys. This prospective study provides evidence for a role of the insula in the establishment and maintenance of social dominance relationships.

The neural activity of auditory conscious perception

Although recent work has made headway in understanding the neural temporospatial dynamics of conscious perception, much of that work has focused on visual paradigms. To determine whether there are shared mechanisms for perceptual consciousness across sensory modalities, here we test within the auditory domain. Participants completed an auditory threshold task while undergoing intracranial electroencephalography. Recordings from >2,800 grey matter electrodes were analyzed for broadband gamma power (a range which reflects local neural activity). For perceived trials, we find nearly simultaneous activity in early auditory regions, the right caudal middle frontal gyrus, and the non-auditory thalamus; followed by a wave of activity that sweeps through auditory association regions into parietal and frontal cortices. For not perceived trials, significant activity is restricted to early auditory regions. These findings show the cortical and subcortical networks involved in auditory perception are similar to those observed with vision, suggesting shared mechanisms for conscious perception.

Automatic engagement of limbic and prefrontal networks in response to food images reflects distinct information about food hedonics and inhibitory control

Adaptive regulation of food consumption involves both identifying food as well as evaluating whether it should be eaten, a process that requires assessing relevant properties such as healthfulness and hedonic value. In order to identify how these fine-grained food properties are represented in the brain, we analyzed functional Magnetic Resonance Imaging data from 43 participants who viewed images of 36 different foods. A data-driven clustering approach based on Representational Similarity Analysis partitioned food-responsive brain regions into two sub-networks based on their multivariate response to food pictures: a Prefrontal network composed of fronto-parietal brain regions and a Limbic network composed of cortico-limbic and sub-cortical brain regions. Further analysis, using similarity judgments of those foods from a large online sample, revealed that the Prefrontal network predominantly represented information related to food healthfulness or processing, the key factor underlying food similarity. In another imaging task, we found that responses in the Prefrontal network were strongly influenced by judgments of food-related self-control, while the Limbic network responses were more affected by hedonic food judgments. These results suggest that, upon viewing food images, behaviorally relevant information is automatically retrieved from distinct brain networks that act as opponent processes in guiding food consumption.

Cognitive and clinical dimensions of structural and functional insula alterations in patients with depression: a resting-state fMRI study

Aim: Depression is characterized by pervasive cognitive and emotional disturbances, yet the neural mechanisms underlying these deficits remain incompletely understood. Method: This study utilized multimodal neuroimaging, including resting-state functional MRI and structural T1-weighted imaging, alongside the MATRICS Consensus Cognitive Battery (MCCB) and the Hamilton Depression Rating Scale (HAMD), to delineate the structural and functional alterations in the insula in first-episode, medication-naïve patients with depression. Result: Compared to matched healthy controls, patients with depression exhibited significant reductions in gray matter density in the left insula, which were robustly associated with impairments in reasoning and problem-solving abilities. Mediation analyses revealed that insular gray matter density mediated the relationship between depressive symptom severity and cognitive deficits, emphasizing the insula's critical role in linking emotional and cognitive dysfunctions. Furthermore, functional connectivity analyses identified disrupted insula-medial prefrontal cortex circuits, highlighting their contribution to the pathophysiology of depression. Conclusion: These findings underscore the insula's dual role as a structural and functional hub in depression, advancing our understanding of the neural substrates of cognitive dysfunction and informing potential targets for intervention.

Evidence for domain-general arousal from semantic and neuroimaging meta-analyses reconciles opposing views on arousal

Arousal refers to changes in brain-body state underpinning motivated behavior but lacks a proper definition and taxonomy. Neuroscience and psychology textbooks offer surprisingly different views on what arousal is, from a global brain-wide modulation of neuronal activity to a multidimensional construct, with specific brain-body patterns tuned to a given situation. The huge number of scientific articles mentioning arousal (~50,000) highlights the importance of the concept but also explains why such a vast literature has never been systematically reviewed so far. Here, we leverage the tools of natural language processing to probe the nature of arousal in a data-driven, comprehensive manner. We show that arousal comes in seven varieties: cognitive, emotional, physiological, sexual, related to stress disorders, to sleep, or to sleep disorders. We then ask whether domain-general arousal exists at the cortical level, and run meta-analyses of the brain imaging literature to reveal that all varieties of arousal, except arousal in sleep disorders for lack of data, converge onto a cortical network composed of the presupplementary motor area and the left and right dorsal anterior insula. More precisely, we find that activity in dysgranular insular area 7 (Jülich atlas), the region with the highest convergence across varieties of arousal, is also specifically associated with arousal. The domain-general arousal network might trigger the reorganization of large-scale brain networks-a global mechanism-resulting in a context-specific configuration-in line with the multidimensional view. Future taxonomies of arousal refining the alignment between concepts and data should include domain-general arousal as a central component.

Altered Effective Connectivity During Threat Anticipation in Individuals With Alcohol Use Disorder

BACKGROUND

A developing theory and recent research suggest that heightened reactivity to uncertain stressors or threats may be an important individual difference factor that facilitates excessive drinking as a means of avoidance-based coping and characterizes individuals with current and past alcohol use disorder (AUD). Neuroimaging studies of unpredictable threat processing have repeatedly demonstrated activation of the anterior insula, anteromedial thalamus, and dorsal anterior cingulate cortex. In the current study, we aimed to understand how these 3 regions function as a network during anticipation of unpredictable threat (and predictable threat).

METHODS

Participants were 43 adults (ages 21-30) with AUD and 26 healthy control participants. Functional magnetic resonance imaging and dynamic causal modeling were used to study interregional effective connectivities and predictable and unpredictable threat-related modulations thereof within this network. Parametric empirical Bayesian modeling was used to conduct between-group comparisons in effective connectivities.

RESULTS

During unpredictable threat trials, the increased projection from the right anteromedial thalamus to the right anterior insula was significantly present only in the AUD group. This directional influence was stronger among individuals who consumed more drinks per week on average. As expected, we found no group differences in modulatory changes to effective connectivities during predictable threat trials.

CONCLUSIONS

To our knowledge, this is the first study to examine directional interactions between key frontolimbic regions during anticipation of unpredictable and predictable threat and demonstrate the importance of bottom-up thalamic-insular projections during unpredictable threat processing in AUD. Prospective studies are warranted to determine whether this association is causal.

Static and Dynamic Cross-Network Functional Connectivity Shows Elevated Entropy in Schizophrenia Patients

Schizophrenia (SZ) patients exhibit abnormal static and dynamic functional connectivity across various brain domains. We present a novel approach based on static and dynamic inter-network connectivity entropy (ICE), which represents the entropy of a given network's connectivity to all the other brain networks. This novel approach enables the investigation of how connectivity strength is heterogeneously distributed across available targets in both SZ patients and healthy controls. We analyzed fMRI data from 151 SZ patients and 160 demographically matched healthy controls (HC). Our assessment encompassed both static and dynamic ICE, revealing significant differences in the heterogeneity of connectivity levels across available functional brain networks between SZ patients and HC. These networks are associated with subcortical (SC), auditory (AUD), sensorimotor (SM), visual (VIS), cognitive control (CC), default mode network (DMN), and cerebellar (CB) functional brain domains. Elevated ICE observed in individuals with SZ suggests that patients exhibit significantly higher randomness in the distribution of time-varying connectivity strength across functional regions from each source network, compared to HC. C-means fuzzy clustering analysis of functional ICE correlation matrices revealed that SZ patients exhibit significantly higher occupancy weights in clusters with weak, low-scale functional entropy correlation, while the control group shows greater occupancy weights in clusters with strong, large-scale functional entropy correlation. K-means clustering analysis on time-indexed ICE vectors revealed that cluster with highest ICE have higher occupancy rates in SZ patients whereas clusters characterized by lowest ICE have larger occupancy rates for control group. Furthermore, our dynamic ICE approach revealed that in HC, the brain primarily communicates through complex, less structured connectivity patterns, with occasional transitions into more focused patterns. Individuals with SZ are significantly less likely to attain these more focused and structured transient connectivity patterns. The proposed ICE measure presents a novel framework for gaining deeper insight into mechanisms of healthy and diseased brain states and represents a useful step forward in developing advanced methods to help diagnose mental health conditions.

The neural network of sensory attenuation: A neuroimaging meta-analysis

Sensory attenuation refers to the reduction in sensory intensity resulting from self-initiated actions compared to stimuli initiated externally. A classic example is scratching oneself without feeling itchy. This phenomenon extends across various sensory modalities, including visual, auditory, somatosensory, and nociceptive stimuli. The internal forward model proposes that during voluntary actions, an efferent copy of the action command is sent out to predict sensory feedback. This predicted sensory feedback is then compared with the actual sensory feedback, leading to the suppression or reduction of sensory stimuli originating from self-initiated actions. To further elucidate the neural mechanisms underlying sensory attenuation effect, we conducted an extensive meta-analysis of functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) studies. Utilizing activation likelihood estimation (ALE) analysis, our results revealed significant activations in a prominent cluster encompassing the right superior temporal gyrus (rSTG), right middle temporal gyrus (rMTG), and right insula when comparing external-generated with self-generated conditions. Additionally, significant activation was observed in the right anterior cerebellum when comparing self-generated to external-generated conditions. Further analysis using meta-analytic connectivity modeling (MACM) unveiled distinct brain networks co-activated with the rMTG and right cerebellum, respectively. Based on these findings, we propose that sensory attenuation arises from the suppression of reflexive inputs elicited by self-initiated actions through the internal forward modeling of a cerebellum-centered action prediction network, enabling the "sensory conflict detection" regions to effectively discriminate between inputs resulting from self-induced actions and those originating externally.

Epilepsy surgery in children with operculoinsular epilepsy: Results of a large unicentric cohort

OBJECTIVE

Epilepsy surgery in the operculoinsular cortex is challenging due to the difficult delineation of the epileptogenic zone and the high risk of postoperative deficits.

METHODS

Pre- and postsurgical data from 30 pediatric patients who underwent operculoinsular cortex surgery at the Motol Epilepsy Center Prague from 2010 to 2022 were analyzed.

RESULTS

Focal cortical dysplasia (FCD; n = 15, 50%) was the predominant cause of epilepsy, followed by epilepsy-associated tumors (n = 5, 17%) and tuberous sclerosis complex (n = 2, 7%). In eight patients where FCD was the most likely etiology, the histology was negative. Seven patients (23%) displayed normal magnetic resonance imaging results. Seizures exhibited diverse semiology and propagation patterns (frontal, perisylvian, and temporal). The ictal and interictal electroencephalographic (EEG) findings were mostly extensive. Multimodal imaging and advanced postprocessing were frequently used. Stereo-EEG was used for localizing the epileptogenic zone and eloquent cortex in 23 patients (77%). Oblique electrodes were used as guides for better neurosurgeon orientation. The epileptogenic zone was in the dominant hemisphere in 16 patients. At the 2-year follow-up, 22 patients (73%) were completely seizure-free, and eight (27%) experienced a seizure frequency reduction of >50% (International League Against Epilepsy class 3 and 4). Fourteen patients (47%) underwent antiseizure medication tapering; treatment was completely withdrawn in two (7%). Nineteen patients (63%) remained seizure-free following the definitive outcome assessment (median = 6 years 5 months, range = 2 years to 13 years 5 months postsurgery). Six patients (20%) experienced corona radiata or basal ganglia ischemia; four (13%) improved to mild and one (3%) to moderate hemiparesis. Two patients (7%) operated on in the anterior insula along with frontotemporal resection experienced major complications: pontine ischemia and postoperative brain edema.

SIGNIFICANCE

Epilepsy surgery in the operculoinsular cortex can lead to excellent patient outcomes. A comprehensive diagnostic approach is crucial for surgical success. Rehabilitation brings a great chance for significant recovery of postoperative deficits.

The Anterior Insula Engages in Feature- and Context-Level Predictive Coding Processes for Recognition Judgments

Predictive coding mechanisms facilitate detection and perceptual recognition, thereby influencing recognition judgements, and, broadly, perceptual decision-making. The anterior insula (AI) has been shown to be involved in reaching a decision about discrimination and recognition, as well as to coordinate brain circuits related to reward-based learning. Yet, experimental studies in the context of recognition and decision-making, targeting this area and based on formal trial-by-trial predictive coding computational quantities, are sparse. The present study goes beyond previous investigations and provides a predictive coding computational account of the role of the AI in recognition-related decision-making, by leveraging Zaragoza-Jimenez et al. (2023) open fMRI dataset (17 female, 10 male participants) and computational modeling, characterized by a combination of view-independent familiarity learning and contextual learning. Using model-based fMRI, we show that, in the context a two-option forced-choice identity recognition task, the AI engages in feature-level (i.e., view-independent familiarity) updating and error signaling processes and context-level familiarity updating to reach a recognition judgment. Our findings highlight that an important functional property of the AI is to update the level of familiarity of a given stimulus while also adapting to task-relevant, contextual information. Ultimately, these expectations, combined with input visual signals through reciprocally interconnected feedback and feedforward processes, facilitate recognition judgments, thereby guiding perceptual decision-making.

Sex Differences in Spatiotemporal Consistency and Effective Connectivity of the Precuneus in Autism Spectrum Disorder

Autism spectrum disorder (ASD) has been reported to exhibit altered local functional consistency. However, previous studies mainly focused on male samples and explored the temporal consistency in the ASD brain ignoring the spatial consistency. In this study, FOur-dimensional Consistency of local neural Activities (FOCA) analysis was used to investigate the sex differences of local spatiotemporal consistency of spontaneous brain activity in ASD. This study used resting-state functional magnetic resonance imaging data from the Autism Brain Imaging Data Exchange database, including 64 males/64 females with ASD and 64 male/64 female neurotypical controls (NCs). Two-way analysis of variance was performed to ascertain diagnosis-by-sex interaction effects on whole brain FOCA maps. Moreover, granger causal analysis was used to investigate effective connectivity between the brain regions with interaction effects and the whole-brain in ASD. Significant diagnosis-by-sex interaction effects on FOCA were observed in the bilateral precuneus (PCUN), bilateral medial prefrontal cortex and right dorsolateral superior frontal gyrus. Specifically, FOCA was significantly increased in males with ASD but decreased in females with ASD in the PCUN compared with the sex-matched NC group. In addition, the lack of sex differences in the causal influences from the bilateral anterior cingulate cortex/medial prefrontal cortex to the PCUN was observed in ASD. Our results reveal altered sex differences in the spatiotemporal consistency of spontaneous brain activity and functional interaction of the anterior and posterior default mode network (DMN) in ASD, highlighting the critical role of the DMN in the sex heterogeneity of ASD.

An Island of Reil excitation: Mapping glutamatergic (vGlut1+ and vGlut2+) connections in the medial insular cortex

The insular cortex is a multifunctional and richly connected region of the cerebral cortex, critical in the neural integration of external stimuli and internal signals. Well-served for this role by a large network of afferent and efferent connections, the mouse insula can be simplified into an anterior, medial and posterior portion. Here we focus on the medial subregion, a once over-looked area that has gained recent attention for its involvement in an array of behaviours. Although the connections of medial insular cortex neurons have been previously identified, their precise glutamatergic phenotype remains undefined (typically defined by the presence of the subtype of vesicular glutamate transporters). Hence, we combined Cre knock-in mouse lines and adeno-associated viral tracing to distinguish between the expression of the two major vesicular glutamate transporters, type 1 (vGlut1) and 2 (vGlut2), in the subregion's neuronal inputs and outputs. Our results determined that the medial insula has extensive glutamatergic efferents expressing both vGlut1 and vGlut2 throughout the neuraxis. In contrast, a more conservative number of glutamatergic inputs were observed, with exclusively vGlut2+ projections received from hypothalamic and thalamic regions. Taken together, we demonstrate that vGlut1- and vGlut2-expressing networks of this insular subdivision have distinct connectivity patterns, including a greater abundance of vGlut1+ fibres innervating hypothalamic regions and the extended amygdala. These findings provide insight into the distinct chemo-architecture of this region, which may facilitate further investigation into the role of the medial insula in complex behaviour.

Update on the Neurobiology of Borderline Personality Disorder: A Review of Structural, Resting-State and Task-Based Brain Imaging Studies

PURPOSE OF REVIEW

This review summarizes recent advances in research on the neurobiology of borderline personality disorder (BPD) according to structural brain imaging investigations and resting-state and task-based functional brain activation studies.

RECENT FINDINGS

Extending established findings on differences in regional brain volumes and cortical thickness between BPD and healthy controls, recent research illuminates shared and distinct brain structural characteristics compared to other psychiatric diagnoses, and uncovers relations of these brain structures with transdiagnostic symptoms and clinical features. Resting-state functional brain imaging studies reveal disruptions among adolescents and adults with BPD in frontolimbic and default-mode networks, which primarily underlie affect regulation and self-referential processes, respectively. Recent task-based functional brain imaging research builds on existing neurobiological understanding of emotion and cognition in BPD by revealing novel intersections with interpersonal- and stress-related processes. Studies of psychological and pharmacological interventions suggest possible effects on neural regions underlying emotion processing and behavioral control. Recent advances in neurobiological research on BPD underscore the pathophysiology of affective, behavioral and self-interpersonal symptoms, with growing interest in adolescents with BPD and the impacts of psychological and biological interventions. Corresponding with the increased prominence of alternative dimensional models of personality disorder in recent years, there is a gradual rise in studies examining the relationships of brain structures and functional brain activation with BPD-relevant symptom dimensions, including within transdiagnostic samples.

Spatiotemporal Mapping of Auditory Onsets during Speech Production

The human auditory cortex is organized according to the timing and spectral characteristics of speech sounds during speech perception. During listening, the posterior superior temporal gyrus is organized according to onset responses, which segment acoustic boundaries in speech, and sustained responses, which further process phonological content. When we speak, the auditory system is actively processing the sound of our own voice to detect and correct speech errors in real time. This manifests in neural recordings as suppression of auditory responses during speech production compared with perception, but whether this differentially affects the onset and sustained temporal profiles is not known. Here, we investigated this question using intracranial EEG recorded from seventeen pediatric, adolescent, and adult patients with medication-resistant epilepsy while they performed a reading/listening task. We identified onset and sustained responses to speech in the bilateral auditory cortex and observed a selective suppression of onset responses during speech production. We conclude that onset responses provide a temporal landmark during speech perception that is redundant with forward prediction during speech production and are therefore suppressed. Phonological feature tuning in these "onset suppression" electrodes remained stable between perception and production. Notably, auditory onset responses and phonological feature tuning were present in the posterior insula during both speech perception and production, suggesting an anatomically and functionally separate auditory processing zone that we believe to be involved in multisensory integration during speech perception and feedback control.

Insular Epilepsy: Functions, Diagnostic Approaches, and Surgical Interventions

Epilepsy, a chronic neurological disorder characterized by recurrent seizures, affects a significant portion of the global population, with drug-resistant epilepsy (DRE) presenting a major treatment challenge. Insular epilepsy, originating from this complex region, exhibits a broad range of symptoms, making diagnosis particularly difficult. Advanced imaging techniques and invasive procedures like stereoelectroencephalography (SEEG) are often crucial for accurately localizing the epileptogenic zone. Surgical resection remains the primary treatment for DRE, with recent advancements in microsurgical techniques and neuroimaging improving outcomes. Additionally, minimally invasive approaches like laser interstitial thermal therapy (LITT) and radiofrequency thermocoagulation (RFTC) offer promising alternatives.

Let's focus on the insula in addiction: A refined anatomical exploration of insula in severe alcohol and cocaine use disorders

BACKGROUND

Theoretical and empirical contributions have identified insula as key in addiction. However, anatomical modifications of the insula in addictive states, and their variations across substance use disorders (SUDs), remain to be specifically explored. We therefore explored the specificities and commonalities of insula gray matter (GM) alterations in severe alcohol use disorder (sAUD) and severe cocaine use disorder (sCUD).

METHODS

We explored insula GM volume through a refined parcellation in 12 subregions (six bilateral): anterior inferior cortex (AIC), anterior short gyrus, middle short gyrus, posterior short gyrus, anterior long gyrus (ALG), and posterior long gyrus (PLG). Using a linear mixed model analysis, we explored the insula volume profiles of 50 patients with sAUD, 61 patients with sCUD, and 36 healthy controls (HCs).

RESULTS

In both sAUD and sCUD, we showed overall insular lower volume with a right-sided lateralization effect, and a major volume deficit in bilateral ALG. Moreover, differences emerged across groups, with higher left AIC and PLG volume deficits in sCUD compared to sAUD and HC.

CONCLUSIONS

We offered the first joint exploration of GM insular volumes in two SUD through refined parcellation, thus unveiling the similarities and dissimilarities in volume deficit profiles. Our results bring evidence complementing prior ones suggesting the core role of the right and posterior insula in craving and interoception, two crucial processes in addiction. Left AIC and PLG group differences also show that, while insula is a region of interest in SUD, sCUD and sAUD generate distinct insular profiles, which might parallel clinical differences across SUD.

Specific structural changes in Parkinson's disease-related olfactory dysfunction compared to others forms of olfactory dysfunction

Context

Olfactory dysfunction (OD) is a common early symptom of Parkinson’s disease (PD). However, OD is not specific to PD, as approximatively 20% of the general population exhibit different forms of OD. To use olfactory measures for early Parkinson screening, it is crucial to distinguish PD-related OD from Non-Parkinsonian OD (NPOD).

Objectives and hypothesis

This study aimed to compare the structural changes associated with PD-related OD (n = 15) with NPOD (n = 15), focusing on gray matter volumes and white matter fiber integrity in chemosensory regions. We hypothesized that PD-related OD presents specific structural alterations in these regions.

Methods

Participants underwent a 3 T MRI scan, which included anatomical T1 and diffusion-weighted imaging. Gray and white matter integrity were assessed using both whole-brain analyses (voxel-based morphometry—VBM and tract-based spatial statistics—TBSS, respectively) and localized approaches, including regions of interest and tractography.

Results

PD patients exhibited significantly higher gray matter volume in the left insula using restricted regions-of-interest analyses, while no other significant gray or white matter differences were found between groups.

Conclusion

Structural imaging of the gray matter, particularly the insula, but not of white matter, differentiates PD-related OD from NPOD.

The Insular Cortex: An Interface Between Sensation, Emotion and Cognition

The insula is a complex brain region central to the orchestration of taste perception, interoception, emotion, and decision-making. Recent research has shed light on the intricate connections between the insula and other brain regions, revealing the crucial role of this area in integrating sensory, emotional, and cognitive information. The unique anatomical position and extensive connectivity allow the insula to serve as a critical hub in the functional network of the brain. We summarize its role in interoceptive and exteroceptive sensory processing, illustrating insular function as a bridge connecting internal and external experiences. Drawing on recent research, we delineate the insular involvement in emotional processes, highlighting its implications in psychiatric conditions, such as anxiety, depression, and addiction. We further discuss the insular contributions to cognition, focusing on its significant roles in time perception and decision-making. Collectively, the evidence underscores the insular function as a dynamic interface that synthesizes diverse inputs into coherent subjective experiences and decision-making processes. Through this review, we hope to highlight the importance of the insula as an interface between sensation, emotion, and cognition, and to inspire further research into this fascinating brain region.

Insights from Ecstatic Epilepsy: From Uncertainty to Metacognitive Feelings

Ecstatic epilepsy is a rare form of focal epilepsy linked to the anterior insula in which patients experience a blissful state with a unique set of symptoms, including a feeling of physical well-being, mental clarity, a sense of oneness with the universe, and time dilation. In this chapter, we reflect on how these symptoms coincide with our current knowledge of the insula's functions and explore how this stunning natural model can further inform our understanding of the insula's role in the sentient self, uncertainty and surprise monitoring, and metacognitive feelings.

Bulimia nervosa selectively reshapes the structure and intrinsic function of anterior insula subregions associated with cognition-emotion integration

BACKGROUND

Existing evidence suggests that anterior insula plays a crucial role in cognitive control and emotional regulation and is implicated in the onset and maintenance of bulimia nervosa (BN). However, it remains unclear how structural and functional abnormalities in specific subregions of anterior insula contribute to BN.

METHODS

In this study, we analyzed structural MRI and resting-state functional MRI data from 54 BN patients and 56 healthy controls (HCs). We conducted voxel-based morphometry, amplitude of low frequency fluctuation (conventional band: 0.01-0.08 Hz, slow-5: 0.01-0.027 Hz) and seed-based whole-brain functional connectivity (FC) analysis of the anterior insula subregions for both groups. Additionally, we investigated the correlation between neuroimaging findings and clinical characteristics in the BN group.

RESULTS

Our findings revealed that BN patients exhibited reduced gray matter volume in the right dorsal anterior insula (dAI) and bilateral ventral anterior insula (vAI) and demonstrated decreased ALFF in slow-5 band of bilateral dAI. The BN group also showed increased FC between bilateral dAI and precuneus or right superior frontal gyri which significantly correlated with the severity of BN or its key symptom. In addition, the decreased FC between bilateral vAI and anterior cingulate and paracingulate gyri and/or median cingulate and paracingulate gyri were both significantly correlated with the severity and its restrained eating behavior.

CONCLUSIONS

Our findings further indicate that the functional separation of anterior insula subregions may underlie the pathophysiology of BN. Notably, the vAI associated with emotional processing may serve as a promising neuroimaging biomarker which could inform therapeutic strategy.

The Contribution of Cognitive Control Networks in Word Selection Processing in Parkinson's Disease: Novel Insights from a Functional Connectivity Study

Parkinson's disease (PD) patients are impaired in word production when the word has to be selected among competing alternatives requiring higher attentional resources. In PD, word selection processes are correlated with the structural integrity of the inferior frontal gyrus, which is critical for response selection, and the uncinate fasciculus, which is necessary for processing lexical information. In early PD, we investigated the role of the main cognitive large-scale networks, namely the salience network (SN), the central executive networks (CENs), and the default mode network (DMN), in word selection. Eighteen PD patients and sixteen healthy controls were required to derive nouns from verbs or generate verbs from nouns. Participants also underwent a resting-state functional MRI. Functional connectivity (FC) was examined using independent component analysis. Functional seeds for the SN, CENs, and DMN were defined as spheres, centered at the local activation maximum. Correlations were calculated between the FC of each functional seed and word production. A significant association between SN connectivity and task performance and, with less evidence, between CEN connectivity and the task requiring selection among a larger number of competitors, emerged in the PD group. These findings suggest the involvement of the SN and CEN in word selection in early PD, supporting the hypothesis of impaired executive control.

Transient alteration of Awareness triggered by direct electrical stimulation of the brain

BACKGROUND

Awareness is a state of consciousness that enables a subject to interact with the environment. Transient alteration of awareness (AA) is a disabling sign of many types of epileptic seizures. The brain mechanisms of awareness and its alteration are not well known.

OBJECTIVE/HYPOTHESIS

Transient and isolated AA induced by electrical brain stimulation during a stereoelectroencephalography (SEEG) recording represents an ideal model for studying the associated modifications of functional connectivity and locating the hubs of awareness networks.

METHODS

We investigated the SEEG signals-based brain functional connectivity (FC) changes vs background occurring during AA triggered by three thalamic and two insular stimulations in three patients explored by SEEG in the frame of presurgical evaluation for focal drug-resistant epilepsy. The results were compared to the stimulations of the same sites that did not induce clinical changes (negative stimulations).

RESULTS

We observed decreased node strength in the pulvinar, insula, and parietal associative cortices during the thalamic and insular stimulations that induced AA. The link strengths characterizing functional coupling between the thalamus and the insular, prefrontal, temporal, or parietal associative cortices were also decreased. In contrast, there was an increased synchronization between the precuneus and the temporal lateral cortex. These FC changes were absent during the negative stimulations.

CONCLUSION

Our study highlights the role of the pulvinar, insular, and parietal hubs in maintaining the awareness networks and paves the way for invasive or non-invasive neuromodulation protocols to reduce AA manifestations during epileptic seizures.

Itching Frequency and Neuroanatomic Correlates in Frontotemporal Lobar Degeneration

Importance

Itching is common in geriatric populations and is frequently linked to dermatological or systemic conditions. Itching engages specific brain regions that are implicated in the pathogenesis of frontotemporal lobar degeneration spectrum disorders (FTLD-SD). Thus, itching of undetermined origin (IUO) may indicate the presence of a neurodegenerative process.

Objective

To compare the frequency of itching in FTLD-SD and Alzheimer disease (AD) and to determine the neuroanatomical underpinnings of IUO.

Design, Setting, and Participants

This case-control study evaluated data and brain magnetic resonance images (MRIs) for participants with FTLD-SD or AD. Participants of a research study on FTLD-SD at the University of California, San Francisco, Memory and Aging Center were evaluated from May 1, 2002, to December 31, 2021. The exposure group underwent structural brain MRI within 6 months of initial diagnosis. Research visit summaries were reviewed to validate qualitative details and accurately identify itching with undetermined origin (IUO).

Exposures

Symptoms suggestive of FTLD-SD or AD.

Main Outcomes and Measures

Frequency of itching in FTLD-SD and AD and neuroanatomic correlates.

Results

A total of 2091 research visit summaries were reviewed for 1112 patients exhibiting symptoms indicative of FTLD-SD or AD. From 795 records where itching or a related phrase was endorsed, 137 had IUO. A total of 454 participants were included in the study: 137 in the itching group (mean [SD] age, 62.7 [9.9] years; 74 [54%] females and 63 males [46%]) and 317 in the nonitching group (mean [SD] age, 60.7 [10.8] years; 154 [49%] females and 163 males [51%]). Groups were similar in age, sex, and disease severity. More frequent itching was found in FTLD-SD (95/248 patients [38%], of which 44 [46%] had behavioral variant frontotemporal dementia [bvFTD]) compared with the AD group (14/77 patients [18%]; P = .001). The odds of itching were 2.4 (95% CI, 1.48-3.97) times higher for FTLD-SD compared with all other cases of dementia. Compared with healthy controls, the group with IUO exhibited greater gray matter atrophy bilaterally in the amygdala, insula, precentral gyrus, and cingulum, as well as in the right frontal superior gyrus and thalamus. Among patients with bvFTD and itching vs bvFTD without itching, itching was associated with right-lateralized gray matter atrophy affecting the insula, thalamus, superior frontal gyrus, and cingulum.

Conclusions and Relevance

Among individuals with IUO, FTLD-SD was disproportionately represented compared with AD. In FTLD-SD, dysfunction in the right anterior insula and its connected regions, including the right precentral gyrus, cingulum, and bilateral amygdala, contribute to dysregulation of the itching-scratching networks, resulting in uncontrollable itching or skin picking. Awareness among physicians about the relationship between neurodegeneration and itching may help in the management of itch in older individuals. Further studies are needed to determine the best treatments for these symptoms in patients with neurodegenerative disorders.

Transcranial direct current stimulation improves heart rate variability: A systematic review and meta-analysis

BACKGROUND

Heart rate variability (HRV) is a useful tool for evaluating cardiovascular autonomic nervous system (ANS) functions. This systematic review and meta-analysis examined the potential effects of transcranial direct current stimulation (tDCS) protocols on HRV parameters.

METHODS

This study acquired 97 comparisons from 24 qualified studies for data synthesis. Using standardized mean difference (SMD), individual and overall effect sizes were estimated to show differences in HRV variables between active tDCS and sham stimulation conditions. More positive effect size values indicated that active tDCS caused greater increases in HRV than sham stimulation. Furthermore, moderator variable analyses were performed to determine whether changes in HRV variables differed depending on (a) task types (physical stress versus psychological stress versus resting condition), (b) targeted brain regions, (c) stimulation polarity, (d) characteristics of participants, and (e) specific HRV variables. Finally, we used meta-regression analyses to determine whether different tDCS parameters (i.e., the number of tDCS sessions, stimulation duration, and density) were associated with changes in HRV patterns.

RESULTS

The random-effects model meta-analysis showed that tDCS protocols significantly improved HRV variables (SMD = 0.400; P < 0.001). Moreover, for increasing HRV during the physical stress task (SMD = 1.352; P = 0.001), anodal stimulation on the M1 was effective, while combined polarity stimulation on the PFC improved HRV during the psychological stress task (SMD = 0.550; P < 0.001) and resting condition (SMD = 0.192; P = 0.012). Additional moderator variables and meta-regression analyses failed to show that tDCS protocols had positive effects in certain conditions, such as different stimulus polarity, characteristics of participants, specific HRV variables, and tDCS parameters.

CONCLUSION

These findings tentatively suggest that using tDCS protocols to stimulate optimal targeted brain areas may be effective in improving HRV patterns potentially related to cardiovascular ANS functions.

Heart rate and insula activity increase in response to music in individuals with high interoceptive sensitivity

Interoception plays an important role in emotion processing. However, the neurobiological substrates of the relationship between visceral responses and emotional experiences remain unclear. In the present study, we measured interoceptive sensitivity using the heartbeat discrimination task and investigated the effects of individual differences in interoceptive sensitivity on changes in pulse rate and insula activity in response to subjective emotional intensity. We found a positive correlation between heart rate and valence level when listening to music only in the high interoceptive sensitivity group. The valence level was also positively correlated with music-elicited anterior insula activity. Furthermore, a region of interest analysis of insula subregions revealed significant activity in the left dorsal dysgranular insula for individuals with high interoceptive sensitivity relative to individuals with low interoceptive sensitivity while listening to the high-valence music pieces. Our results suggest that individuals with high interoceptive sensitivity use their physiological responses to assess their emotional level when listening to music. In addition, insula activity may reflect the use of interoceptive signals to estimate emotions.

Clinical symptoms and neuroanatomical substrates of daytime sleepiness in Parkinson's disease

Clinical and neuroanatomical correlates of daytime sleepiness in Parkinson's disease (PD) remain inconsistent in the literature. Two studies were conducted here. The first evaluated the interrelation between non-motor and motor symptoms, using a principal component analysis, associated with daytime sleepiness in PD. The second identified the neuroanatomical substrates associated with daytime sleepiness in PD using magnetic resonance imaging (MRI). In the first study, 77 participants with PD completed an extensive clinical, cognitive testing and a polysomnographic recording. In the second study, 29 PD participants also underwent MRI acquisition of T1-weighted images. Vertex-based cortical and subcortical surface analysis, deformation-based morphometry, and voxel-based morphometry were performed to assess the association between daytime sleepiness severity and structural brain changes in participants. In both studies, the severity of daytime sleepiness and the presence of excessive daytime sleepiness (EDS; total score >10) were measured using the Epworth Sleepiness Scale. We found that individuals with EDS had a higher score on a component including higher dosage of dopamine receptor agonists, motor symptoms severity, shorter sleep latency, and greater sleep efficiency. Moreover, increased daytime sleepiness severity was associated with a larger surface area in the right insula, contracted surfaces in the right putamen and right lateral amygdala, and a larger surface in the right posterior amygdala. Hence, daytime sleepiness in PD was associated with dopaminergic receptor agonists dosage, motor impairment, and objective sleep measures. Moreover, neuroanatomical changes in cortical and subcortical regions related to vigilance, motor, and emotional states were associated with more severe daytime sleepiness.

Association of chronotype with language and episodic memory processing in children: implications for brain structure

Introduction

Chronotype refers to individual preference in circadian cycles and is associated with psychiatric problems. It is mainly classified into early (those who prefer to be active in the morning and sleep and wake up early) and late (those who prefer to be active in the evening and sleep and wake up late) chronotypes. Although previous research has demonstrated associations between chronotype and cognitive function and brain structure in adults, little is known regarding these associations in children. Here, we aimed to investigate the relationship between chronotype and cognitive function in children. Moreover, based on the significant association between chronotype and specific cognitive functions, we extracted regions-of-interest (ROI) and examined the association between chronotype and ROI volumes.

Methods

Data from 4,493 children (mean age of 143.06 months) from the Adolescent Brain Cognitive Development Study were obtained, wherein chronotype (mid-sleep time on free days corrected for sleep debt on school days) was assessed by the Munich Chronotype Questionnaire. Subsequently, the associations between chronotype, cognitive function, and ROI volumes were evaluated using linear mixed-effects models.

Results

Behaviorally, chronotype was negatively associated with vocabulary knowledge, reading skills, and episodic memory performance. Based on these associations, the ROI analysis focused on language-related and episodic memory-related areas revealed a negative association between chronotype and left precentral gyrus and right posterior cingulate cortex volumes. Furthermore, the precentral gyrus volume was positively associated with vocabulary knowledge and reading skills, while the posterior cingulate cortex volume was positively associated with episodic memory performance.

Discussion

These results suggest that children with late chronotype have lower language comprehension and episodic memory and smaller brain volumes in the left precentral gyrus and right posterior cingulate cortex associated with these cognitive functions.

Functional Brain Mapping Using Depth Electrodes

OBJECTIVE

This study investigated the neurologic symptoms and stimulus intensities in the stimulation of deep structures and subcortical fibers with the depth electrodes.

METHODS

Seventeen patients with drug-refractory epilepsy who underwent functional brain mapping with the depth electrodes were enrolled. The 50 Hz electrical stimulation was applied, and the diffusion tensor image was used to identify subcortical fibers. The responsible structures and stimulus intensities for the induced neurologic symptoms were evaluated.

RESULTS

Neurologic symptoms were induced in 11 of 17 patients. The opercular stimulation elicited the neurologic symptoms in 6 patients at the median threshold of 4.0 mA (visceral/face/hand sensory, hand/throat motor, negative motor and auditory symptoms). The insular stimulation induced the neurologic symptoms in 4 patients at the median threshold of 4.0 mA (auditory, negative motor, and sensory symptoms). The stimulation of subcortical fibers was induced in 5 of 9 patients at the median threshold of 4.5 mA. The thresholds of depth electrodes were significantly lower than those of subdural electrodes in 8 patients who used both subdural and depth electrodes and induced symptoms with both electrodes.

CONCLUSIONS

The stimulation of depth electrodes can identify the function of deep structures and subcortical fibers with lower intensities than subdural electrodes.

Resting-State Functional Connectivity Profile of Insular Subregions

The insula is often considered the fifth lobe of the brain and is increasingly recognized as one of the most connected regions in the brain, with widespread connections to cortical and subcortical structures. As a follow-up to our previous tractography work, we investigated the resting-state functional connectivity (rsFC) profiles of insular subregions and assessed their concordance with structural connectivity. We used the CONN toolbox to analyze the rsFC of the same 19 insular regions of interest (ROIs) we used in our prior tractography work and regrouped them into six subregions based on their connectivity pattern similarity. Our analysis of 50 healthy participants confirms the known broad connectivity of the insula and shows novel and specific whole-brain and intra-connectivity patterns of insular subregions. By examining such subregions, our findings provide a more detailed pattern of connectivity than prior studies that may prove useful for comparison between patients.

The Clinical Impact of Real-Time fMRI Neurofeedback on Emotion Regulation: A Systematic Review

Emotion dysregulation has long been considered a key symptom in multiple psychiatric disorders. Difficulties in emotion regulation have been associated with neural dysregulation in fronto-limbic circuits. Real-time fMRI-based neurofeedback (rt-fMRI-NFB) has become increasingly popular as a potential treatment for emotional dysregulation in psychiatric disorders, as it is able to directly target the impaired neural circuits. However, the clinical impact of these rt-fMRI-NFB protocols in psychiatric populations is still largely unknown. Here we provide a comprehensive overview of primary studies from 2010 to 2023 that used rt-fMRI-NFB to target emotion regulation. We assessed 41 out of 4001 original studies for methodological quality and risk of bias and synthesised concerning the frequency of significant rt-fMRI-NFB-related effects on the neural and behaviour level. Successful modulation of brain activity was reported in between 25 and 50 percent of study samples, while neural effects in clinical samples were more diverse than in healthy samples. Interestingly, the frequency of rt-fMRI-NFB-related behavioural improvement was over 75 percent in clinical samples, while healthy samples showed behavioural improvements between 0 and 25 percent. Concerning clinical subsamples, rt-fMRI-NFB-related behavioural improvement was observed in up to 100 percent of major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) samples. Substance use samples showed behavioural benefits ranging between 50 and 75 percent. Neural effects appeared to be less frequent than behavioural improvements: most neural outcomes ranged between 25 and 50 percent for MDD and substance use and between 0 and 25 percent for PTSD. Using multiple individualised regions of interest (ROIs) for rt-fMRI-NFB training resulted in more frequent behavioural benefits than rt-fMRI-NFB solely based on the amygdala or the prefrontal cortex. While a significant improvement in behavioural outcomes was reported in most clinical studies, the study protocols were heterogeneous, which limits the current evaluation of rt-fMRI-NFB as a putative treatment for emotional dysregulation.

Normativity vs. uniqueness: effects of social relationship strength on neural representations of others

Understanding others involves inferring traits and intentions, a process complicated by our reliance on stereotypes and generalized information when we lack personal information. Yet, as relationships are formed, we shift toward nuanced and individualized perceptions of others. This study addresses how relationship strength influences the creation of unique or normative representations of others in key regions known to be involved in social cognition. Employing a round-robin interpersonal perception paradigm (N = 111, 20 groups of five to six people), we used functional magnetic resonance imaging to examine whether the strength of social relationships modulated the degree to which multivoxel patterns of activity that represented a specific other were similar to a normative average of all others in the study. Behaviorally, stronger social relationships were associated with more normative trait endorsements. Neural findings reveal that closer relationships lead to more unique representations in the medial prefrontal cortex and anterior insula, areas associated with mentalizing and person perception. Conversely, more generalized representations emerge in posterior regions like the posterior cingulate cortex, indicating a complex interplay between individuated and generalized processing of social information in the brain. These findings suggest that cortical regions typically associated with social cognition may compute different kinds of information when representing the distinctiveness of others.

The functional connectivity between right insula and anterior cingulate cortex underlying the association between future self-continuity and delay discounting

Delay discounting refers to the tendency of individuals to devalue future rewards as the delay in their receipt increases over time. Previous studies have indicated that future self-continuity correlates with delay discounting rates. However, the neural basis underlying the relationship between future self-continuity and delay discounting is not clear. To address this question, we used voxel-based morphometry and resting-state functional connectivity analyses to investigate the neural basis underlying the association between future self-continuity and delay discounting. Behavioral result showed that future self-continuity was positively associated with delay discounting. Voxel-based morphometry analysis result indicated that gray matter volume in the right dorsal anterior insula was positively correlated with future self-continuity. Resting-state functional connectivity analysis found that functional connectivity between the right dorsal anterior insula and anterior cingulate cortex was positively associated with future self-continuity. Mediation analysis showed that the right dorsal anterior insula-right anterior cingulate cortex functional connectivity partially mediated the relationship between future self-continuity and delay discounting. These results suggested that right dorsal anterior insula-right anterior cingulate cortex functional connectivity could be the neural basis underlying the association between future self-continuity and delay discounting. In summary, the study provided novel insights into how future self-continuity affected delay discounting and offers new explanations from a neural perspective.

Noninvasive neuromodulation of subregions of the human insula differentially affect pain processing and heart-rate variability: a within-subjects pseudo-randomized trial

ABSTRACT

The insula is an intriguing target for pain modulation. Unfortunately, it lies deep to the cortex making spatially specific noninvasive access difficult. Here, we leverage the high spatial resolution and deep penetration depth of low-intensity focused ultrasound (LIFU) to nonsurgically modulate the anterior insula (AI) or posterior insula (PI) in humans for effect on subjective pain ratings, electroencephalographic (EEG) contact heat-evoked potentials, as well as autonomic measures including heart-rate variability (HRV). In a within-subjects, repeated-measures, pseudo-randomized trial design, 23 healthy volunteers received brief noxious heat pain stimuli to the dorsum of their right hand during continuous heart-rate, electrodermal, electrocardiography and EEG recording. Low-intensity focused ultrasound was delivered to the AI (anterior short gyrus), PI (posterior longus gyrus), or under an inert Sham condition. The primary outcome measure was pain rating. Low-intensity focused ultrasound to both AI and PI similarly reduced pain ratings but had differential effects on EEG activity. Low-intensity focused ultrasound to PI affected earlier EEG amplitudes, whereas LIFU to AI affected later EEG amplitudes. Only LIFU to the AI affected HRV as indexed by an increase in SD of N-N intervals and mean HRV low-frequency power. Taken together, LIFU is an effective noninvasive method to individually target subregions of the insula in humans for site-specific effects on brain biomarkers of pain processing and autonomic reactivity that translates to reduced perceived pain to a transient heat stimulus.