Ventromedial prefrontal cortex and the regulation of physiological arousal

Elemental and configural representation of a conditioned context

A context can be conceptualized as a stable arrangement of elements or as the sum of single elements. Both configural and elemental representations play a role in associative processes. This study aimed to explore the respective contributions of these two representations of a context in the acquisition of conditioned anxiety in humans. Virtual reality (VR) can be an ecologically valid tool to investigate context-related mechanisms, yet the influence of the sense of presence within the virtual environment remains unclear. Forty-eight healthy individuals participated in a VR-based context conditioning wherein electric shocks (unconditioned stimulus, US) were unpredictably delivered in one virtual office (CTX+), but not in the other (CTX-). During the test phase, nine elements from each context were presented singularly. We found a cluster of participants, who exhibited heightened anticipation of the US for anxiety-related elements as compared to the other group. In contrast to their clear elemental representation, these individuals showed diminished discriminative responses between the two context's configurations. Discriminative responses to the contexts were boosted in those individuals, who had a weaker elemental representation. Importantly, the individual sense of presence significantly influenced the conditioned responses. These findings align with the dual-representation view of context and provide insights into the role of presence in eliciting (conditioned) anxiety responses.

The effects of music and auditory stimulation on autonomic arousal, cognition and attention: A systematic review

According to the arousal-mood hypothesis, changes in arousal and mood when exposed to auditory stimulation underlie the detrimental effects or improvements in cognitive performance. Findings supporting or against this hypothesis are, however, often based on subjective ratings of arousal rather than autonomic/physiological indices of arousal. To assess the arousal-mood hypothesis, we carried out a systematic review of the literature on 31 studies investigating cardiac, electrodermal, and pupillometry measures when exposed to different types of auditory stimulation (music, ambient noise, white noise, and binaural beats) in relation to cognitive performance. Our review suggests that the effects of music, noise, or binaural beats on cardiac, electrodermal, and pupillometry measures in relation to cognitive performance are either mixed or insufficient to draw conclusions. Importantly, the evidence for or against the arousal-mood hypothesis is at best indirect because autonomic arousal and cognitive performance are often considered separately. Future research is needed to directly evaluate the effects of auditory stimulation on autonomic arousal and cognitive performance holistically.

Neural signatures of shared subjective affective engagement and disengagement during movie viewing

When watching a negative emotional movie, we differ from person to person in the ease with which we engage and the difficulty with which we disengage throughout a temporally evolving narrative. We investigated neural responses of emotional processing, by considering inter-individual synchronization in subjective emotional engagement and disengagement. The neural underpinnings of these shared responses are ideally studied in naturalistic scenarios like movie viewing, wherein individuals emotionally engage and disengage at their own time and pace throughout the course of a narrative. Despite the rich data that naturalistic designs can bring to the study, there is a challenge in determining time-resolved behavioral markers of subjective engagement and disengagement and their underlying neural responses. We used a within-subject cross-over design instructing 22 subjects to watch clips of either neutral or sad content while undergoing functional magnetic resonance imaging (fMRI). Participants watched the same movies a second time while continuously annotating the perceived emotional intensity, thus enabling the mapping of brain activity and emotional experience. Our analyses revealed that between-participant similarity in waxing (engagement) and waning (disengagement) of emotional intensity was directly related to the between-participant similarity in spatiotemporal patterns of brain activation during the movie(s). Similar patterns of engagement reflected common activation in the bilateral ventromedial prefrontal cortex, regions often involved in self-referenced evaluation and generation of negative emotions. Similar patterns of disengagement reflected common activation in central executive and default mode network regions often involved in top-down emotion regulation. Together this work helps to better understand cognitive and neural mechanisms underpinning engagement and disengagement from emotionally evocative narratives.

Non-invasive stimulation reveals ventromedial prefrontal cortex function in reward prediction and reward processing

Introduction

Studies suggest an involvement of the ventromedial prefrontal cortex (vmPFC) in reward prediction and processing, with reward-based learning relying on neural activity in response to unpredicted rewards or non-rewards (reward prediction error, RPE). Here, we investigated the causal role of the vmPFC in reward prediction, processing, and RPE signaling by transiently modulating vmPFC excitability using transcranial Direct Current Stimulation (tDCS).

Methods

Participants received excitatory or inhibitory tDCS of the vmPFC before completing a gambling task, in which cues signaled varying reward probabilities and symbols provided feedback on monetary gain or loss. We collected self-reported and evaluative data on reward prediction and processing. In addition, cue-locked and feedback-locked neural activity via magnetoencephalography (MEG) and pupil diameter using eye-tracking were recorded.

Results

Regarding reward prediction (cue-locked analysis), vmPFC excitation (versus inhibition) resulted in increased prefrontal activation preceding loss predictions, increased pupil dilations, and tentatively more optimistic reward predictions. Regarding reward processing (feedback-locked analysis), vmPFC excitation (versus inhibition) resulted in increased pleasantness, increased vmPFC activation, especially for unpredicted gains (i.e., gain RPEs), decreased perseveration in choice behavior after negative feedback, and increased pupil dilations.

Discussion

Our results support the pivotal role of the vmPFC in reward prediction and processing. Furthermore, they suggest that transient vmPFC excitation via tDCS induces a positive bias into the reward system that leads to enhanced anticipation and appraisal of positive outcomes and improves reward-based learning, as indicated by greater behavioral flexibility after losses and unpredicted outcomes, which can be seen as an improved reaction to the received feedback.

How Obstructed Action Efficacy Impacts Reward-based Decision-making in Adolescent Depression: An fMRI Study

OBJECTIVE

Disruption of reward seeking behavior by unforeseen obstacles can promote negative affect, including frustration and irritability, in adolescents. Repeated experiences of obstructed reward may in fact contribute to the development of depression in adolescents. However, the neurocognitive mechanisms whereby goal disruption impacts reward processing in adolescent depression have not yet been characterized. The present study addresses this gap using neuroimaging and a novel paradigm to assess how incidental action obstruction impacts reward-based decision-making.

METHOD

We assessed 62 unmedicated adolescents with Major Depressive Disorder (MDD; mean age=15.6, SD=1.4, 67% female participants) and 68 matched healthy control participants (mean age=15.3, SD=1.4, 50% female participants) using functional magnetic resonance imaging (fMRI) while they played a card game in which they had to guess between two options to earn points, in low- and high-stake conditions. Functioning of button presses through which they made decisions was intermittently blocked, thereby blocking action efficacy.

RESULTS

Participants with MDD made fewer button press repetitions in response to action efficacy obstruction, which was more apparent in the low-stake condition (Rate Ratio =0.85, p=0.034). During response repetition across stake conditions, MDDs exhibited higher activation in regions in the ventromedial prefrontal cortex, caudate, and putamen (F_(1,125)= 16.4-25.6, df=1,125; ps<0.001; Hedges' g=0.85-0.98).

CONCLUSION

Adolescent with depression tend to exhibit less flexible behavioral orientation in the face of blocked action efficacy, and abnormalities in neural systems critical to regulating negative affect during reward-based decision-making. This research highlights possible mechanisms relevant to understanding and treating affective dysregulation in adolescent depression.

The impact of sociality and affective valence on brain activation: A meta-analysis

Thirty years of neuroimaging reveal the set of brain regions consistently associated with pleasant and unpleasant affect in humans-or the neural reference space for valence. Yet some of humans' most potent affective states occur in the context of other humans. Prior work has yet to differentiate how the neural reference space for valence varies as a product of the sociality of affective stimuli. To address this question, we meta-analyzed across 614 social and non-social affective neuroimaging contrasts, summarizing the brain regions that are consistently activated for social and non-social affective information. We demonstrate that across the literature, social and non-social affective stimuli yield overlapping activations within regions associated with visceromotor control, including the amygdala, hypothalamus, anterior cingulate cortex and insula. However, we find that social processing differs from non-social affective processing in that it involves additional cortical activations in the medial prefrontal and posterior cingulum that have been associated with mentalizing and prediction. A Bayesian classifier was able to differentiate unpleasant from pleasant affect, but not social from non-social affective states. Moreover, it was not able to classify unpleasantness from pleasantness at the highest levels of sociality. These findings suggest that highly social scenarios may be equally salient to humans, regardless of their valence.

The effects of stimulant and non-stimulant medications on the autonomic nervous system (ANS) functioning in people with ADHD: A systematic review and meta-analysis

We carried out a systematic review and meta-analysis to investigate the effects of stimulant and non-stimulant medications on autonomic functioning in people with ADHD (PROSPERO: CRD42020212439). We searched (9th August 2021) PsycInfo, MEDLINE, EMBASE, Web of Science and The Cochrane Library, for randomised and non-randomised studies reporting indices of autonomic activity, (electrodermal, pupillometry and cardiac), pre- and post-medication exposure in people meeting DSM/ICD criteria for ADHD. In the narrative syntheses, we included 5 electrodermal studies, 1 pupillometry study and 57 studies investigating heart rate and blood pressure. In the meta-analyses, 29 studies were included on blood pressure and 32 on heart rate. Administration of stimulants, and to a lesser degree, non-stimulants increased heart rate and blood pressure in people with ADHD. Similarly, an upregulation of arousal, reflected in increased electrodermal activity and pupil diameter was observed following stimulant use. Yet, the methodological diversity of studies presented in this review reinforces the need for more standardised and rigorous research to fully understand the relationship between arousal, medication, and behaviour in ADHD.

Behavioral impulsivity is associated with pupillary alterations and hyperactivity in CDKL5 mutant mice

Cyclin-dependent kinase-like 5 (Cdkl5) deficiency disorder (CDD) is a severe neurodevelopmental condition caused by mutations in the X-linked Cdkl5 gene. CDD is characterized by early-onset seizures in the first month of life, intellectual disability, motor and social impairment. No effective treatment is currently available and medical management is only symptomatic and supportive. Recently, mouse models of Cdkl5 disorder have demonstrated that mice lacking Cdkl5 exhibit autism-like phenotypes, hyperactivity and dysregulations of the arousal system, suggesting the possibility to use these features as translational biomarkers. In this study, we tested Cdkl5 male and female mutant mice in an appetitive operant conditioning chamber to assess cognitive and motor abilities, and performed pupillometry to assess the integrity of the arousal system. Then, we evaluated the performance of artificial intelligence models to classify the genotype of the animals from the behavioral and physiological phenotype. The behavioral results show that CDD mice display impulsivity, together with low levels of cognitive flexibility and perseverative behaviors. We assessed arousal levels by simultaneously recording pupil size and locomotor activity. Pupillometry reveals in CDD mice a smaller pupil size and an impaired response to unexpected stimuli associated with hyperlocomotion, demonstrating a global defect in arousal modulation. Finally, machine learning reveals that both behavioral and pupillometry parameters can be considered good predictors of CDD. Since early diagnosis is essential to evaluate treatment outcomes and pupillary measures can be performed easily, we proposed the monitoring of pupil size as a promising biomarker for CDD.

Gray matter volumes of the insula and anterior cingulate cortex and their dysfunctional roles in cigarette smoking

The salience network, including the insula and anterior cingulate cortex (ACC), has been implicated in nicotine addiction. Structural imaging studies have reported diminished insula and ACC gray matter volumes (GMVs) in smokers as compared to nonsmokers. However, it remains unclear how insula and ACC GMVs may relate to years of smoking, addiction severity, or behavioral traits known to dispose individuals to smoking. Here, with a dataset curated from the Human Connectome Project and voxel-based morphometry, we replicated the findings of smaller GMVs of the insula and medial prefrontal cortex, including the dorsal ACC and supplementary motor area (dACC/SMA), in (70 heavy < 209 light < 209 never) smokers matched in age, sex, and average daily num ber of drinks. The GMVs of the insula or dACC/SMA were not significantly correlated with years of smoking or Fagerstrom Test for Nicotine Dependence (FTND) scores. Heavy relative to never smokers demonstrated higher externalizing and internalizing scores, as evaluated by the NIH Emotion. In heavy smokers, the dACC/SMA but not insula GMV was positively correlated with both externalizing and internalizing scores. The findings together confirm volumetric changes in the salience network in heavy smokers and suggest potentially distinct dysfunctional roles of the insula and dACC/SMA in chronic smoking.

Autonomic system tuning during gesture observation and reproduction

Gestural communication allows providing information about thoughts and feelings, characterizing face-to-face interactions, also during non-verbal exchanges. In the present study, the autonomic responses and peripheral synchronization mechanisms of two individuals (encoder and decoder) were recorded simultaneously, through the use of biofeedback in hyperscanning, during two different experimental phases consisting in the observation (watching videos of gestures) and reproduction of positive and negative different types of gestures (affective, social and informative) supported by linguistic contexts. Therefore, the main aim of this study was focused on the analysis of simultaneous individuals' peripheral mechanisms during the performing of complex joint action, consisting of the observation (watching videos) and the reproduction of positive and negative social, affective, and informative gestures each supported by a linguistic script. Single-subject and inter-subject correlation analyses were conducted to observe individuals' autonomic responses and physiological synchronization. Single-subject results revealed an increase in emotional arousal, indicated by an increase in electrodermal activity (skin conductance level - SCL and response - SCR), during both the observation (watching videos) and reproduction of negative social and affective gestures contextualized by a linguistic context. Moreover, an increase of emotional engagement, expressed by an increase in heart rate (HR) activity, emerged in the encoder compare to the decoder during gestures reproduction (simulation of gestures). Inter-subject correlation results showed the presence of mirroring mechanisms, indicated by an increase in SCL, SCR, and HR synchronization, during the linguistic contexts and gesture observation (watching videos). Furthermore, an increase in SCL and SCR synchronization emerged during the observation (watching videos) and reproduction of negative social and affective gestures. Therefore, the present study allowed to obtain information on the mirroring mechanisms and physiological synchronization underlying the linguistic and gesture system during non-verbal interaction.

Skin Conductance Responses to a Discrete Threat in Virtual Reality: Associations with Psychopathy and Anxiety

People with high levels of psychopathic traits are often described as fearless and lacking in emotional depth, particularly when evaluating threats in their environments. Skin conductance responsivity (SCR) to negative emotional stimuli represents a robust autonomic correlate of conduct problem behavior in children (Fanti et al., in Neuroscience and Biobehavioral Reviews, 100, 98-107, 2019). However, studies that have examined threat-related processing in youth with conduct problems have tended to use a variety of negative stimuli that might induce various and unspecific negative emotions. Few studies have taken in to account the moderating effects of anxiety on the relationship of distinct psychopathic traits (e.g., narcissism, callousness, impulsivity) with SCR to a fear inducing stimulus. In this study, we examined SCR to a virtual reality rollercoaster drop - that is, a discrete fear inducing event - in a sample of 75 youths (61 males; M = 14 years, SD = 1.4) enrolled in a non-mainstream school. The rollercoaster drop was used to more clearly examine an event-related response to a discrete threat, rather than examining SCR throughout the rollercoaster ride. We used the teacher-reported Antisocial Process Screening Device (Frick & Hare, in Antisocial process screening device: APSD. Toronto: Multi-Health Systems, 2001) to examine the relations of distinct psychopathic traits with SCR and self-reported anxiety. Lower anxiety was associated with higher callousness, but only in youths with low SCR to discrete threat. These findings suggest that fear and anxiety show complex and interactive relations with distinct psychopathic traits.

Habitual use of psychological coping strategies is associated with physiological stress responding during negative memory recollection in humans

Research has identified a variety of strategies people use to cope with stress and that the adaptiveness of various strategies depends on the context in which they are used. However, important questions remain about the role of physiological stress response systems in supporting, influencing, or changing from coping strategies. This study works toward addressing this gap by examining associations between skin conductance level (SCL) and habitual use of coping strategies. It was hypothesized that more use of problem-focused strategies would be associated with SCL trajectories that were more stable and decreased less steeply, with the opposite trend hypothesized for more use of emotion-focused strategies. Participants were 188 college students (78% female) who reported their use of 14 coping strategies. SCL was recorded during recall of a negative family memory from childhood for five minutes. Trajectories of SCL during the recall were estimated with multilevel modeling. Greater self-distraction, planning, active coping, use of emotional support, and coping flexibility were related to trajectories of SCL that decreased less steeply and were more stable. Problem-focused coping and coping flexibility are, therefore, related to reduced SCL reactivity and promoting these skills may benefit mental health.

Threat imminence reveals links among unfolding of anticipatory physiological response, cortical-subcortical intrinsic functional connectivity, and anxiety

Excessive expression of fear responses in anticipation of threat occurs in anxiety, but understanding of underlying pathophysiological mechanisms is limited. Animal research indicates that threat-anticipatory defensive responses are dynamically organized by threat imminence and rely on conserved circuitry. Insight from basic neuroscience research in animals on threat imminence could guide mechanistic research in humans mapping abnormal function in this circuitry to aberrant defensive responses in pathological anxiety. 50 pediatric anxiety patients and healthy-comparisons (33 females) completed an instructed threat-anticipation task whereby cues signaled delivery of painful (threat) or non-painful (safety) thermal stimulation. Temporal changes in skin-conductance indexed anxiety effects on anticipatory responding as function of threat imminence. Multivariate network analyses of resting-state functional connectivity data from a subsample were used to identify intrinsic-function correlates of anticipatory-response dynamics, within a specific, distributed network derived from translational research on defensive responding. By considering threat imminence, analyses revealed specific anxiety effects. Importantly, pathological anxiety was associated with excessive deployment of anticipatory physiological response as threat, but not safety, outcomes became more imminent. Magnitude of increase in threat-anticipatory physiological responses corresponded with magnitude of intrinsic connectivity within a cortical-subcortical circuit. Moreover, more severe anxiety was associated with stronger associations between anticipatory physiological responding and connectivity that ventromedial prefrontal cortex showed with hippocampus and basolateral amygdala, regions implicated in animal models of anxiety. These findings link basic and clinical research, highlighting variations in intrinsic function in conserved defensive circuitry as a potential pathophysiological mechanism in anxiety.

Dysregulated arousal as a pathway linking childhood neglect and clinical sleep disturbances in adulthood

BACKGROUND

A history of childhood maltreatment has a well-established association with clinical sleep disturbances in adulthood, which is a transdiagnostic contributor to many chronic diseases.

OBJECTIVE

Determine whether actigraphy-measured indices of dysregulated arousal during sleep explain associations between abuse or neglect in childhood and clinical sleep disturbances in adulthood.

PARTICIPANTS AND SETTING

Participants were 646 individuals, ages 25-83 (59.3% female) from the MIDUS II Biomarker, Refresher studies.

METHODS

Participants completed the Childhood Trauma Questionnaire, wore an actigraph for seven days, and rated sleep quality using the Pittsburgh Sleep Quality Index (PSQI).

RESULTS

Both neglect (b = 0.66, SE = 0.33, p = .04) and abuse (b = 1.09, SE = 0.32, p < .001) were associated with clinical sleep disturbance. Actigraphy-measured sleep efficiency mediated the link between neglect and clinical sleep disturbances (ab = 0.33, SE = 0.12, 95%CI [0.12, 0.57]). However, no such link between abuse and clinical sleep disturbances was mediated by actigraphy-measured indices. Sleep onset latency did not mediate the link between neglect or abuse and sleep disturbance. Models covaried for other maltreatment, gender, and age.

CONCLUSIONS

While the unique associations between abuse or neglect and clinical sleep disturbances were robust in this sample, only sleep efficiency emerged as a mediator linking maltreatment and clinical sleep disturbances. Critically, this mediation was specific to neglect. Abuse and neglect may lead to disease through distinct pathways. Moreover, potential dysregulation in arousal that leads to sleep inefficiency may be a specific pathway through which experiences of neglect in childhood contribute to chronic disease.

Contextual modulation of conditioned responses in humans: A review on virtual reality studies

Conditioned response (CRs) triggered by stimuli predicting aversive consequences have been confirmed across various species including humans, and were found to be exaggerated in anxious individuals and anxiety disorder patients. Importantly, contextual information may strongly modulate such conditioned responses (CR), however, there are several methodological boundaries in the translation of animal findings to humans, and from healthy individuals to patients. Virtual Reality (VR) is a useful technological tool for overcoming such boundaries. In this review, we summarize and evaluate human VR conditioning studies exploring the role of the context as conditioned stimulus or occasion setter for CRs. We observe that VR allows successful acquisition of conditioned anxiety and conditioned fear in response to virtual contexts and virtual cues, respectively. VR studies also revealed that spatial or temporal contextual information determine whether conditioned anxiety and conditioned fear become extinguished and/or return. Novel contexts resembling the threatening context foster conditioned fear but not conditioned anxiety, suggesting distinct context-related generalization processes. We conclude VR contexts are able to strongly modulate CRs and therefore allow a comprehensive investigation of the modulatory role of the context over CR in humans leading to conclusions relevant for non-VR and clinical studies.

Neural correlates of interoceptive accuracy: Beyond cardioception

Interoceptive accuracy (IAc), the precision with which one assesses the signals arising from one's own body, is receiving increasing attention in the literature. IAc has mainly been approached as an individual trait and has been investigated through the cardiac modality using mostly non-ecological methods. Such studies consensually designate the anterior insular cortex as the main brain correlate of IAc. However, there is a lack of brain imaging studies investigating IAc in a broader and more ecological way. Here, we used a novel ecological task in which participants monitored their general bodily reactions to external events and investigated brain regions subtending intraindividual (i.e. trial-by-trial) variations of IAc. At each trial, participants had to rate the intensity of their bodily reactions to an emotional picture. We recorded participants' skin conductance response (SCR) to the picture as an indicator of actual physiological response intensity. We fitted a functional magnetic resonance imaging (fMRI) model using, as regressors, the SCR value, the rating and the product of the two (as a proxy of participants' IAc) obtained trial per trial. We observed that activity in the dorsomedial prefrontal cortex (dmPFC) increased when individuals' IAc decreased. This result reveals general mechanism of error processing in intraindividual variations of IAc, which are unspecific to interoception. Our result has a practical impact in the clinical domain. Namely, it supports the predictive coding framework whereby IAc deficits may reflect impairments in processing a mismatch between actual interoceptive signals and predictions.

Differential Modulation of Effective Connectivity in the Brain's Extended Face Processing System by Fearful and Sad Facial Expressions

The processing of emotional facial expressions is underpinned by the integration of information from a distributed network of brain regions. Despite investigations into how different emotional expressions alter the functional relationships within this network, there remains limited research examining which regions drive these interactions. This study investigated effective connectivity during the processing of sad and fearful facial expressions to better understand how these stimuli differentially modulate emotional face processing circuitry. Ninety-eight healthy human adolescents and young adults, aged between 15 and 25 years, underwent an implicit emotional face processing fMRI task. Using dynamic causal modeling (DCM), we examined five brain regions implicated in face processing. These were restricted to the right hemisphere and included the occipital and fusiform face areas, amygdala, and dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC). Processing sad and fearful facial expressions were associated with greater positive connectivity from the amygdala to dlPFC. Only the processing of fearful facial expressions was associated with greater negative connectivity from the vmPFC to amygdala. Compared with processing sad faces, processing fearful faces was associated with significantly greater connectivity from the amygdala to dlPFC. No difference was found between the processing of these expressions and the connectivity from the vmPFC to amygdala. Overall, our findings indicate that connectivity from the amygdala and dlPFC appears to be responding to dimensional features which differ between these expressions, likely those relating to arousal. Further research is necessary to examine whether this relationship is also observable for positively valenced emotions.

A Voxel-based lesion study on facial emotion recognition after circumscribed prefrontal cortex damage

Previous studies have shown inconsistent findings regarding the contribution of the different prefrontal regions in emotion recognition. Moreover, the hemispheric lateralization hypothesis posits that the right hemisphere is dominant for processing all emotions regardless of affective valence, whereas the valence specificity hypothesis posits that the left hemisphere is specialized for processing positive emotions while the right hemisphere is specialized for negative emotions. However, recent findings suggest that the evidence for such lateralization has been less consistent. In this study, we investigated emotion recognition of fear, surprise, happiness, sadness, disgust, and anger in 30 patients with focal prefrontal cortex lesions and 30 control subjects. We also examined the impact of lesion laterality on recognition of the six basic emotions. The results showed that compared to control subjects, the frontal subgroups were impaired in recognition of three negative basic emotions of fear, sadness, and anger - regardless of the lesion laterality. Therefore, our findings did not establish that each hemisphere is specialized for processing specific emotions. Moreover, the voxel-based lesion symptom mapping analysis showed that recognition of fear, sadness, and anger draws on a partially common bilaterally distributed prefrontal network.

Correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks

Autonomic nervous system (ANS) activity is a core and central component of emotion and motivated action. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP), respectively. Samples combined four previous studies (N = 325, 63% female, aged 15-55) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modelled in order to determine the extent to which SNS and PNS activity is correlated across the task within and between participants, and whether this correlation was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled. However, recovery from a stressor was characterized by coactivation. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, reflecting greater coordination of physiological responding in the former groups.

Cue-elicited functional connectivity of the periaqueductal gray and tonic cocaine craving

BACKGROUND

Withdrawal from chronic cocaine use leads to anxiety and dysphoria that may perpetuate habitual drug use. The pain circuit is widely implicated in the processing and manifestations of negative emotions. Numerous studies have focused on characterizing reward circuit dysfunction but relatively little is known about the pain circuit response during cocaine withdrawal.

METHODS

Here we examined the activity and connectivity of the periaqueductal gray (PAG), a hub of the pain circuit, during cocaine cue exposure in 52 recently abstinent cocaine dependent participants (CD, 42 men). Imaging data were processed with published routines, and the results were evaluated at a corrected threshold.

RESULTS

CD showed higher activation of the PAG and connectivity of the PAG with the ventromedial prefrontal cortex (vmPFC) during cocaine as compared to neutral cue exposure. PAG-vmPFC connectivity was positively and negatively correlated with tonic cocaine craving, as assessed by the Cocaine Craving Questionnaire, in male and female CD, respectively, and the sex difference was confirmed by a slope test. Granger causality analyses showed that the PAG Granger caused vmPFC time series in men and the reverse was true in women, substantiating sex differences in the directional interactions of the PAG and vmPFC.

CONCLUSION

The findings provide the first evidence in humans implicating the PAG circuit in cocaine withdrawal and cocaine craving and advance our understanding of the role of the pain circuit and negative reinforcement in sustaining habitual drug use in cocaine addiction.

Brain Connectivity, and Hormonal and Behavioral Correlates of Sustained Weight Loss in Obese Patients after Laparoscopic Sleeve Gastrectomy

The biological mediators that support cognitive-control and long-term weight-loss after laparoscopic sleeve gastrectomy (LSG) remain unclear. We measured peripheral appetitive hormones and brain functional-connectivity (FC) using magnetic-resonance-imaging with food cue-reactivity task in 25 obese participants at pre, 1 month, and 6 month after LSG, and compared with 30 normal weight controls. We also used diffusion-tensor-imaging to explore whether LSG increases brain structural-connectivity (SC) of regions involved in food cue-reactivity. LSG significantly decreased BMI, craving for high-calorie food cues, ghrelin, insulin, and leptin levels, and increased self-reported cognitive-control of eating behavior. LSG increased FC between the right dorsolateral prefrontal cortex (DLPFC) and the pregenual anterior cingulate cortex (pgACC) and increased SC between DLPFC and ACC at 1 month and 6 month after LSG. Reduction in BMI correlated negatively with increased FC of right DLPFC-pgACC at 1 month and with increased SC of DLPFC-ACC at 1 month and 6 month after LSG. Reduction in craving for high-calorie food cues correlated negatively with increased FC of DLPFC-pgACC at 6 month after LSG. Additionally, SC of DLPFC-ACC mediated the relationship between lower ghrelin levels and greater cognitive control. These findings provide evidence that LSG improved functional and structural connectivity in prefrontal regions, which contribute to enhanced cognitive-control and sustained weight-loss following surgery.

Altered Coupling of Psychological Relaxation and Regional Volume of Brain Reward Areas in Multiple Sclerosis

Background: Psychological stress can influence the severity of multiple sclerosis (MS), but little is known about neurobiological factors potentially counteracting these effects. Objective: To identify gray matter (GM) brain regions related to relaxation after stress exposure in persons with MS (PwMS). Methods: 36 PwMS and 21 healthy controls (HCs) reported their feeling of relaxation during a mild stress task. These markers were related to regional GM volumes, heart rate, and depressive symptoms. Results: Relaxation was differentially linked to heart rate in both groups (t = 2.20, p = 0.017), i.e., both markers were only related in HCs. Relaxation was positively linked to depressive symptoms across all participants (t = 1.99, p = 0.045) although this link differed weakly between groups (t = 1.62, p = 0.108). Primarily, the volume in medial temporal gyrus was negatively linked to relaxation in PwMS (t = -5.55, pfamily-wise-error(FWE)corrected = 0.018). A group-specific coupling of relaxation and GM volume was found in ventromedial prefrontal cortex (VMPFC) (t = -4.89, pFWE = 0.039). Conclusion: PwMS appear unable to integrate peripheral stress signals into their perception of relaxation. Together with the group-specific coupling of relaxation and VMPFC volume, a key area of the brain reward system for valuation of affectively relevant stimuli, this finding suggests a clinically relevant misinterpretation of stress-related affective stimuli in MS.

Reward-Driven Arousal Impacts Preparation to Perform a Task via Amygdala-Caudate Mechanisms

Preparing for a challenging task can increase physiological arousal, in particular when potential incentives are large (e.g., a solo musical performance in front of an audience). Here, we examine how potential reward and its influence on arousal, measured by pupil dynamics, are represented in the brain while preparing for a challenging task. We further ask how neural representations during preparation relate to actual performance. Trials resulting in performance failure were characterized by increased pupil dilation as a function of increasing reward magnitude during preparation. Such failure trials were also associated with activation of the right amygdala representing pupil dilation, and the left caudate representing reward magnitude. Notably, increases in functional connectivity between amygdala and caudate preceded performance failure. These findings highlight increased connectivity between neural regions representing reward and arousal in circumstances where reward-driven arousal impairs performance.

The role of the subgenual anterior cingulate cortex in dorsomedial prefrontal-amygdala neural circuitry during positive-social emotion regulation

Positive-social emotions mediate one's cognitive performance, mood, well-being, and social bonds, and represent a critical variable within therapeutic settings. It has been shown that the upregulation of positive emotions in social situations is associated with increased top-down signals that stem from the prefrontal cortices (PFC) which modulate bottom-up emotional responses in the amygdala. However, it remains unclear if positive-social emotion upregulation of the amygdala occurs directly through the dorsomedial PFC (dmPFC) or indirectly linking the bilateral amygdala with the dmPFC via the subgenual anterior cingulate cortex (sgACC), an area which typically serves as a gatekeeper between cognitive and emotion networks. We performed functional MRI (fMRI) experiments with and without effortful positive-social emotion upregulation to demonstrate the functional architecture of a network involving the amygdala, the dmPFC, and the sgACC. We found that effortful positive-social emotion upregulation was associated with an increase in top-down connectivity from the dmPFC on the amygdala via both direct and indirect connections with the sgACC. Conversely, we found that emotion processes without effortful regulation increased network modulation by the sgACC and amygdala. We also found that more anxious individuals with a greater tendency to suppress emotions and intrusive thoughts, were likely to display decreased amygdala, dmPFC, and sgACC activity and stronger connectivity strength from the sgACC onto the left amygdala during effortful emotion upregulation. Analyzed brain network suggests a more general role of the sgACC in cognitive control and sheds light on neurobiological informed treatment interventions.

Two genetically, anatomically and functionally distinct cell types segregate across anteroposterior axis of paraventricular thalamus

Unlike the sensory thalamus, studies on the functional organization of the midline and intralaminar nuclei are scarce, and this has hindered the establishment of conceptual models of the function of this brain region. We investigated the functional organization of the paraventricular nucleus of the thalamus (PVT), a midline thalamic structure that is increasingly being recognized as a critical node in the control of diverse processes such as arousal, stress, emotional memory and motivation, in mice. We identify two major classes of PVT neurons-termed type I and type II-that differ in terms of gene expression, anatomy and function. In addition, we demonstrate that type II neurons belong to a previously neglected class of PVT neurons that convey arousal-related information to corticothalamic neurons of the infralimbic cortex. Our results uncover the existence of an arousal-modulated thalamo-corticothalamic loop that links the PVT and the ventromedial prefrontal cortex.

Comparing three models of arousal in the human brain

The bipolar valence-arousal model is assumed by many to be an underlying structure of conscious experience of core affect and emotion. In this work, we compare three versions of the bipolar valence-arousal model at the neural domain, using functional magnetic resonance imaging (fMRI). Specifically, we systematically contrast three models of arousal: model 1-'arousal as a separate quale from valence', model 2-'arousal as intensity of bipolar valence' and model 3-'arousal as a linear combination of unipolar pleasant and unpleasant'. Using parametric modulation analysis, we estimated the ability of each model to predict activation in arousal-related brain regions, in response to affective stimuli. The results suggest that arousal is not separable from valence in its ability to predict arousal-related neural activity. The relevance of the results to the theory of conscious affect is discussed.

Gender- and Age-Specific Differences in Resting-State Functional Connectivity of the Central Autonomic Network in Adulthood

Previous functional imaging studies have identified the role of central autonomic network (CAN) in autonomic regulation during various tasks. However, its variability with respect to gender and age, particularly in the resting state, remains poorly understood. Therefore, in this study we systematically investigated gender- and age-related differences in the resting-state functional connectivity (rsFC) seeded from core regions of this network, namely posterior mid-cingulate gyrus (pMCC), left amygdala, right anterior and left posterior insula, and ventromedial prefrontal cortex (vmPFC), using a large cross-sectional adulthood sample. Results revealed that each of the seeded connectivity maps engaged in at least one of the large-scale brain networks including sensorimotor, attentional, basal ganglia, limbic, and default mode networks (DMN). In the early-adulthood stage, females had stronger negative rsFC in pMCC and right anterior INS (aINS) with the medial DMN than males, possibly reflecting their greater suppression of the sympathoexcitation associated with sex hormonal estrogen. Whereas in the late-adulthood stage, they showed stronger positive rsFC in pMCC with postcentral gyrus and weaker negative rsFC with the most DMN, possibly relating to their higher risk of depression, anxiety, and dementia than males after menopause. Moreover, females demonstrated reduced negative rsFC in pMCC with dorsal PCUN/PCC and left AG with advancing age, whereas males showed the opposite pattern, namely increased positive rsFC, in pMCC with right SMG, and in vmPFC with ventral PCUN. We interpret these results as their differences of altered autonomic regulation associated with pain experience and reflective movement, respectively, due to aging. In sum, our findings add in literature that autonomic responses can be also represented intrinsically in the resting brain, and gender- and age-related differences might be associated with sex hormones and sensorimotor abilities, respectively.

Cue-elicited craving, thalamic activity, and physiological arousal in adult non-dependent drinkers

Changes in physiological arousal frequently accompany cognitive and affective challenges. Many studies employed cue exposure paradigms to investigate the neural processes underlying cue-elicited drug and alcohol craving. However, whether cue-elicited craving relates to changes in physiological arousal and the neural bases underlying the potential relationship remain unclear. Here we examined cerebral cue-related activations in relation to differences in skin conductance responses (SCR) recorded during alcohol vs. neutral cue blocks in 61 non-dependent alcohol drinkers (30 men). Imaging and skin conductance data were collected and processed with published routines. Mediation analyses were conducted to examine the inter-relationship between regional activities, cue-elicited craving, and SCR. The results showed higher SCR during alcohol than during neutral cue exposure. Despite no differences in drinking characteristics, men as compared to women demonstrated higher craving rating, and men but not women demonstrated a positive correlation between alcohol (vs. neutral) cue-evoked craving and SCR. Further, across subjects, thalamic cue activity was positively correlated with differences in SCR between alcohol and neutral cue blocks in men but not in women. Mediation analyses suggested that thalamic activity mediated the correlation between craving and SCR across men and women, and in men but not women alone. These findings substantiate physiological and neural correlates of alcohol cue response and suggest important sex differences in the physiological and neural processes of cue evoked craving. Centered on the intralaminar and mediodorsal subregions, the thalamic correlate may represent a neural target for behavioral or pharmacological therapy to decrease cue-elicited arousal and craving.

Ventromedial prefrontal cortex contributes to performance success by controlling reward-driven arousal representation in amygdala

When preparing for a challenging task, potential rewards can cause physiological arousal that may impair performance. In this case, it is important to control reward-driven arousal while preparing for task execution. We recently examined neural representations of physiological arousal and potential reward magnitude during preparation, and found that performance failure was explained by relatively increased reward representation in the left caudate nucleus and arousal representation in the right amygdala (Watanabe, et al., 2019). Here we examine how prefrontal cortex influences the amygdala and caudate to control reward-driven arousal. Ventromedial prefrontal cortex (VMPFC) exhibited activity that was negatively correlated with trial-wise physiological arousal change, which identified this region as a potential modulator of amygdala and caudate. Next we tested the VMPFC - amygdala - caudate effective network using dynamic causal modeling (Friston et al., 2003). Post-hoc Bayesian model selection (Friston and Penny, 2011) identified a model that best fit data, in which amygdala activation was suppressively controlled by the VMPFC only in success trials. Furthermore, fixed connectivity strength from VMPFC to amygdala explained individual task performance. These findings highlight the role of effective connectivity from VMPFC to amygdala in order to control arousal during preparation for successful performance.

Tuning of brain-autonomic coupling by prior threat exposure: Implications for internalizing problems in Mexican-origin adolescents

Exposure to threat increases the risk for internalizing problems in adolescence. Deficits in integrating bodily cues into representations of emotion are thought to contribute to internalizing problems. Given the role of the medial prefrontal cortex in regulating bodily responses and integrating them into representations of emotional states, coordination between activity in the medial prefrontal cortex and autonomic nervous system responses may be influenced by past threat exposure with consequences for the emergence of internalizing problems. A sample of 179 Mexican-origin adolescents (88 female) reported on neighborhood and school crime, peer victimization, and discrimination when they were 10-16 years old. At age 17, participants underwent a functional neuroimaging scan during which they viewed pictures of emotional faces while respiratory sinus arrhythmia (RSA) and skin conductance responses were measured. Adolescents also reported symptoms of internalizing problems. Greater exposure to threats across adolescence was associated with more internalizing problems. Threat exposure was also associated with stronger negative coupling between the ventromedial prefrontal cortex and RSA. Stronger negative ventromedial prefrontal cortex-RSA coupling was associated with fewer internalizing problems. These results suggest the degree of coordinated activity between the brain and parasympathetic nervous system is both enhanced by threat experiences and decreased in adolescents with more internalizing problems.

Longitudinal changes of amygdala functional connectivity in adolescents prenatally exposed to cocaine

BACKGROUND

Prenatal cocaine exposure (PCE) is associated with arousal dysregulation, but interactions between exposure and age are rarely investigated directly with longitudinal study designs. Our previous study had examined task-elicited emotional arousal and noted persistently high amygdala activations in the development of adolescents with PCE. However, while externally imposed emotional arousal could be considered a "state" effect depending on specific task stimuli, it is still unclear whether similar developmental alterations extend to intrinsic functional connectivity (FC), reflecting more of a "trait" effect.

METHODS

We used a longitudinal design and analyzed resting-state functional magnetic resonance imaging data acquired twice from 25 adolescents with PCE and 16 non-exposed controls. Both groups were each scanned first at the mean age of 14.3 and then again at 16.6 years. Seeding in bilateral amygdalae and comparing the 2^nd scan with the 1^st, we examined the interaction effect between PCE and age on FCs in the emotional network.

RESULTS

Compared with the younger age, we observed a generally decreased FC in the emotional network of the control group at the older age, but these FCs were generally increased at the older age in this same network of the PCE group. Additionally, this interaction effect of exposure by age in the right fusiform was positively correlated with the emotional interference imposed by external task stimuli.

CONCLUSIONS

These results provided additional data directly characterizing developmental changes in the emotional network of adolescents with PCE, complementing and extending the notion of a PCE-associated long-term teratogenic effect on arousal regulation.

Adolescent psychopathy, heart rate, and skin conductance

Researchers have advocated for a greater focus on measuring neurobiological underpinnings of serious psychological conditions such as psychopathy. This has become particularly important to investigate early in the life span, when intervention efforts for psychopathy-related behavior like conduct disorder (CD) are more successful. Given that psychopathy is a complex syndrome, it is also important to investigate physiological processes at a dimensional level. Using a sample of 56 adolescent male offenders (M_age = 15.92; SD = 1.31), this study explored the relationship between the Psychopathy Checklist-Youth Version (Forth, Kosson, & Hare, 2003), heart rate (HR), and skin conductance (SC). A white noise countdown task was used to measure autonomic activity across a baseline, anticipatory (prenoise), and reactivity (postnoise) period. Findings revealed no significant associations between psychopathy and HR activity across the time intervals. However, results revealed a positive association between grandiose-manipulative traits and SC activity and a negative association between callous-unemotional traits and SC activity. The results indicate that autonomic processes may contribute to distinct psychopathic traits in different ways, implicating slightly differential brain functioning. The findings suggest that, in order to better understand and treat youth with CD, future research should continue to examine the biological correlates of psychopathy at the broader construct level but perhaps especially at the component level.

Neural mechanisms of extinguishing drug and pleasant cue associations in human addiction: role of the VMPFC

The neurobiological mechanisms that underlie the resistance of drug cue associations to extinction in addiction remain unknown. Fear extinction critically depends on the ventromedial prefrontal cortex (VMPFC). Here, we tested if this same region plays a role in extinction of non-fear, drug and pleasant cue associations. Eighteen chronic cocaine users and 15 matched controls completed three functional MRI scans. Participants first learned to associate an abstract cue (the conditioned stimulus, CS) with a drug-related (CS_D+ ) or pleasant (CS_P+ ) image. Extinction immediately followed where each CS was repeatedly presented without the corresponding image. Participants underwent a second identical session 24 hours later to assess retention of extinction learning. Results showed that like fear extinction, non-fear-based extinction relies on the VMPFC. However, extinction-related changes in the VMPFC differed by cue valence and diagnosis. In controls, VMPFC activation to the CS_D+ (which was unpleasant for participants) gradually increased as in fear extinction, while it decreased to the CS_P+ , consistent with a more general role of the VMPFC in flexible value updating. Supporting a specific role in extinction retention, we further observed a cross-day association between VMPFC activation and skin conductance, a classic index of conditioned responses. Finally, cocaine users showed VMPFC abnormalities for both CSs, which, in the case of the CS_D+ , correlated with craving. These data suggest a global deficit in extinction learning in this group that may hinder extinction-based treatment efforts. More broadly, these data show that the VMPFC, when functionally intact, supports extinction learning in diverse contexts in humans.

Response inhibition and fronto-striatal-thalamic circuit dysfunction in cocaine addiction

BACKGROUND

Many studies have investigated how cognitive control may be compromised in cocaine addiction. Here, we extend this literature by employing spatial Independent Component Analysis (ICA) to describe circuit dysfunction in relation to impairment in response inhibition in cocaine addiction.

METHODS

Fifty-five cocaine-dependent (CD) and 55 age- and sex-matched non-drug-using healthy control individuals (HC) participated in the study. Task-relatedness of 40 independent components (ICs) was assessed using multiple regression analyses of component time courses with the modeled time courses of hemodynamic activity convolved with go success (GS), stop success (SS) and stop error (SE). This procedure produced beta-weights that represented the degree to which each IC was temporally associated with, or 'engaged', by each task event.

RESULTS

Behaviorally, CD participants showed prolonged stop signal reaction times (SSRTs) as compared to HC participants (p < 0.01). ICA identified two networks that showed differences in engagement related to SS between CD and HC (p < 0.05, FDR-corrected). The activity of the fronto-striatal-thalamic network was negatively correlated with SSRTs in HC but not in CD, suggesting a specific role of this network in mediating deficits of response inhibition in CD individuals. In contrast, the engagement of the fronto-parietal-temporal network did not relate to SSRTs, was similarly less engaged for both SS and SE trials, and may reflect attentional dysfunction in cocaine addiction.

CONCLUSIONS

This study highlights the utility of ICA in identifying neural circuitry engagement related to SST performance and suggests that specific networks may represent important targets in remedying executive-control impairment in cocaine addiction.

Breath of Life: The Respiratory Vagal Stimulation Model of Contemplative Activity

Contemplative practices, such as meditation and yoga, are increasingly popular among the general public and as topics of research. Beneficial effects associated with these practices have been found on physical health, mental health and cognitive performance. However, studies and theories that clarify the underlying mechanisms are lacking or scarce. This theoretical review aims to address and compensate this scarcity. We will show that various contemplative activities have in common that breathing is regulated or attentively guided. This respiratory discipline in turn could parsimoniously explain the physical and mental benefits of contemplative activities through changes in autonomic balance. We propose a neurophysiological model that explains how these specific respiration styles could operate, by phasically and tonically stimulating the vagal nerve: respiratory vagal nerve stimulation (rVNS). The vagal nerve, as a proponent of the parasympathetic nervous system (PNS), is the prime candidate in explaining the effects of contemplative practices on health, mental health and cognition. We will discuss implications and limitations of our model.

Adolescents' brain-autonomic coupling during emotion processing

Autonomic nervous system (ANS) activity is a core component of emotion processing. The limbic system and medial prefrontal cortex play important roles in the regulation of ANS activity. However, the integration of brain activity and ANS activity has yet to be investigated in adolescents despite independent evidence of adolescents' heightened neural and physiological sensitivity to emotional stimuli. The present study examined the relations of ANS activity in the parasympathetic nervous system (PNS) and sympathetic nervous system (SNS) with brain activity during emotional face processing in adolescents. 135 adolescents (65 female; M = 17.15 yr, SD = 0.42) completed an emotional faces task during an fMRI scan while electrocardiography and skin conductance were recorded simultaneously. Using linear mixed-effect modelling, we tested the effect of change in respiratory sinus arrhythmia (RSA), a measure of PNS activity, and number of skin conductance responses (SCRs), a measure of SNS activity, on neural activity while adolescents viewed emotional faces. Greater RSA withdrawal, indicating decreased PNS activity, was associated with increased activation in the ventromedial prefrontal cortex (vmPFC). More SCRs, indicating greater SNS activity, were associated with decreased activation in several regions including the dorsomedial prefrontal cortex and increased activation in the left hippocampus. Left hippocampus-SCR coupling and vmPFC-RSA coupling predicted baseline SCR and RSA respectively. These findings implicate the hippocampus for potentiating SNS activity, document that regulation of SNS and PNS activity are coordinated with distinct regions of the medial prefrontal cortex, and suggest potential developmental differences in vmPFC regulation of PNS activity between adolescents and adults.

Exploring Age-Related Changes in Resting State Functional Connectivity of the Amygdala: From Young to Middle Adulthood

Functional connectivities of the amygdala support emotional and cognitive processing. Life-span development of resting-state functional connectivities (rsFC) of the amygdala may underlie age-related differences in emotion regulatory mechanisms. To date, age-related changes in amygdala rsFC have been reported through adolescence but not as thoroughly for adulthood. This study investigated age-related differences in amygdala rsFC in 132 young and middle-aged adults (19–55 years). Data processing followed published routines. Overall, amygdala showed positive rsFC with the temporal, sensorimotor and ventromedial prefrontal cortex (vmPFC), insula and lentiform nucleus, and negative rsFC with visual, frontoparietal, and posterior cingulate cortex and caudate head. Amygdala rsFC with the cerebellum was positively correlated with age, and rsFCs with the dorsal medial prefrontal cortex (dmPFC) and somatomotor cortex were negatively correlated with age, at voxel p < 0.001 in combination with cluster p < 0.05 FWE. These age-dependent changes in connectivity appeared to manifest to a greater extent in men than in women, although the sex difference was only evident for the cerebellum in a slope test of age regressions (p = 0.0053). Previous studies showed amygdala interaction with the anterior cingulate cortex (ACC) and vmPFC during emotion regulation. In region of interest analysis, amygdala rsFC with the ACC and vmPFC did not show age-related changes. These findings suggest that intrinsic connectivity of the amygdala evolved from young to middle adulthood in selective brain regions, and may inform future studies of age-related emotion regulation and maladaptive development of the amygdala circuits as an etiological marker of emotional disorders.

Disentangling brain activity related to the processing of emotional visual information and emotional arousal

Processing of emotional visual information engages cognitive functions and induces arousal. We aimed to examine the modulatory role of emotional valence on brain activations linked to the processing of visual information and those linked to arousal. Participants were scanned and their pupil size was measured while viewing negative and neutral images. The visual noise was added to the images in various proportions to parametrically manipulate the amount of visual information. Pupil size was used as an index of physiological arousal. We show that arousal induced by the negative images, as compared to the neutral ones, is primarily related to greater amygdala activity while increasing visibility of negative content to enhanced activity in the lateral occipital complex (LOC). We argue that more intense visual processing of negative scenes can occur irrespective of the level of arousal. It may suggest that higher areas of the visual stream are fine-tuned to process emotionally relevant objects. Both arousal and processing of emotional visual information modulated activity within the ventromedial prefrontal cortex (vmPFC). Overlapping activations within the vmPFC may reflect the integration of these aspects of emotional processing. Additionally, we show that emotionally-evoked pupil dilations are related to activations in the amygdala, vmPFC, and LOC.

The role of emotions and physiological arousal in modulating impulsive behaviour

Impulsivity received considerable attention in the context of drug misuse and certain neuropsychiatric conditions. Because of its great health and well-being importance, it is crucial to understand factors which modulate impulsive behaviour. As a growing body of literature indicates the role of emotional and physiological states in guiding our actions and decisions, we argue that current affective state and physiological arousal exert a significant influence on behavioural impulsivity. As 'impulsivity' is a heterogeneous concept, in this paper, we review key theories of the topic and summarise information about distinct impulsivity subtypes and their methods of assessment, pointing out to the differences between the various components of the construct. Moreover, we review existing literature on the relationship between emotional states, arousal and impulsive behaviour and suggest directions for future research.

The Comorbidity Between Internet Gaming Disorder and Depression: Interrelationship and Neural Mechanisms

Internet gaming disorder (IGD) is characterized by cognitive and emotional deficits. Previous studies have reported the co-occurrence of IGD and depression. However, extant brain imaging research has largely focused on cognitive deficits in IGD. Few studies have addressed the comorbidity between IGD and depression symptoms and underlying neural mechanisms. Here, we systematically investigated this issue by combining a longitudinal survey study, a cross-sectional resting-state functional connectivity (rsFC) study and an intervention study. Autoregressive cross-lagged modeling on a longitudinal dataset of college students showed that IGD severity and depression are reciprocally predictive. At the neural level, individuals with IGD exhibited enhanced rsFC between the left amygdala and right dorsolateral prefrontal cortex (DLPFC), inferior frontal and precentral gyrus, compared with control participants, and the amygdala-frontoparietal connectivity at the baseline negatively predicted reduction in depression symptoms following a psychotherapy intervention. Further, following the intervention, individuals with IGD showed decreased connectivity between the left amygdala and left middle frontal and precentral gyrus, as compared with the non-intervention group. These findings together suggest that IGD may be closely associated with depression; aberrant rsFC between emotion and executive control networks may underlie depression and represent a therapeutic target in individuals with IGD. Registry name: The behavioral and brain mechanism of IGD; URL: https://www.clinicaltrials.gov/ct2/show/NCT02550405; Registration number: NCT02550405.

Reduced functional connectivity between ventromedial prefrontal cortex and insula relates to longer corrected QT interval in HIV+ and HIV- individuals

OBJECTIVE

Prolongation of the QT interval, i.e., measure of the time between the start of the Q wave and the end of the T wave, is a precursor to fatal cardiac arrhythmias commonly observed in individuals infected with the Human Immunodeficiency Virus (HIV), and is related to dysregulation of the autonomic nervous system. We investigated the relationship between QT interval length and resting state functional connectivity (rsFC) of the ventromedial prefrontal cortex (VMPFC), a core region of the brain that is involved with cardio-autonomic regulation.

METHOD

Eighteen HIV+ men on antiretroviral therapy and with no history of heart disease were compared with 26 HIV-negative control subjects who had similar demographic and cardio-metabolic characteristics. A seed-based rsFC analysis of the right and left VMPFC was performed at the individual subject level, and 2nd-level analyses were conducted to identify the following: group differences in connectivity, brain regions correlating with corrected (QTc) interval length before and after controlling for those group differences, and regions where seed-based rsFC correlates with CD4 count and QTc interval within HIV+ individuals.

RESULTS

HIV-negative adults showed greater rsFC between the VMPFC seed regions and several default mode network structures. Across groups greater rsFC with the left anterior insula was associated with shorter QTc intervals, whereas right posterior insula connectivity with the VMPFC correlated with greater QTc intervals. HIV patients with lower CD4 counts and higher QTc intervals showed greater rsFC between the right VMPFC and the right posterior insula and dorsal cingulate gyrus.

CONCLUSIONS

This study demonstrates that QTc interval lengths are associated with distinct patterns of VMPFC rsFC with posterior and anterior insula. In HIV patients, longer QTc interval and lower CD4 count corresponded to weaker VMPFC connectivity with the dorsal striatrum.

SIGNIFICANCE

A forebrain control mechanism may be implicated in the suppression of cardiovagal influence that confers risk for ventricular arrhythmias and sudden cardiac death in HIV+ individuals.

Salience Network Connectivity Modulates Skin Conductance Responses in Predicting Arousal Experience

Individual differences in arousal experience have been linked to differences in resting-state salience network connectivity strength. In this study, we investigated how adding task-related skin conductance responses (SCR), a measure of sympathetic autonomic nervous system activity, can predict additional variance in arousal experience. Thirty-nine young adults rated their subjective experience of arousal to emotionally evocative images while SCRs were measured. They also underwent a separate resting-state fMRI scan. Greater SCR reactivity (an increased number of task-related SCRs) to emotional images and stronger intrinsic salience network connectivity independently predicted more intense experiences of arousal. Salience network connectivity further moderated the effect of SCR reactivity: In individuals with weak salience network connectivity, SCR reactivity more significantly predicted arousal experience, whereas in those with strong salience network connectivity, SCR reactivity played little role in predicting arousal experience. This interaction illustrates the degeneracy in neural mechanisms driving individual differences in arousal experience and highlights the intricate interplay between connectivity in central visceromotor neural circuitry and peripherally expressed autonomic responses in shaping arousal experience.

Systemic inflammation and resting state connectivity of the default mode network

The default mode network (DMN) encompasses brain systems that exhibit coherent neural activity at rest. DMN brain systems have been implicated in diverse social, cognitive, and affective processes, as well as risk for forms of dementia and psychiatric disorders that associate with systemic inflammation. Areas of the anterior cingulate cortex (ACC) and surrounding medial prefrontal cortex (mPFC) within the DMN have been implicated specifically in regulating autonomic and neuroendocrine processes that relate to systemic inflammation via bidirectional signaling mechanisms. However, it is still unclear whether indicators of inflammation relate directly to coherent resting state activity of the ACC, mPFC, or other areas within the DMN. Accordingly, we tested whether plasma interleukin (IL)-6, an indicator of systemic inflammation, covaried with resting-state functional connectivity of the DMN among 98 adults aged 30-54 (39% male; 81% Caucasian). Independent component analyses were applied to resting state fMRI data to generate DMN connectivity maps. Voxel-wise regression analyses were then used to test for associations between IL-6 and DMN connectivity across individuals, controlling for age, sex, body mass index, and fMRI signal motion. Within the DMN, IL-6 covaried positively with connectivity of the sub-genual ACC and negatively with a region of the dorsal medial PFC at corrected statistical thresholds. These novel findings offer evidence for a unique association between a marker of systemic inflammation (IL-6) and ACC and mPFC functional connectivity within the DMN, a network that may be important for linking aspects of immune function to psychological and behavioral states in health and disease.

Modifiable Arousal in Attention-Deficit/Hyperactivity Disorder and Its Etiological Association With Fluctuating Reaction Times

Background

Cognitive theories of attention-deficit/hyperactivity disorder (ADHD) propose that high within-subject fluctuations of cognitive performance in ADHD, particularly reaction time (RT) variability (RTV), may reflect arousal dysregulation. However, direct evidence of arousal dysregulation and how it may account for fluctuating RTs in ADHD is limited. We used skin conductance (SC) as a measure of peripheral arousal and aimed to investigate its phenotypic and familial association with RTV in a large sample of ADHD and control sibling pairs.

Methods

Adolescents and young adults (N = 292), consisting of 73 participants with ADHD and their 75 siblings, and 72 controls and their 72 siblings, completed the baseline (slow, unrewarded) and fast-incentive conditions of a RT task, while SC was simultaneously recorded.

Results

A significant group-by-condition interaction emerged for SC level (SCL). Participants with ADHD had decreased SCL, compared with controls, in the baseline condition but not the fast-incentive condition. Baseline SCL was negatively associated with RTV, and multivariate model fitting demonstrated that the covariance of SCL with RTV, and of SCL with ADHD, was mostly explained by shared familial effects.

Conclusions

ADHD is associated with decreased, but modifiable, tonic peripheral arousal. A shared familial cause underlies the relationship between arousal and RTV and between arousal and ADHD. Given the malleability of SCL, if our findings are replicated, it warrants further exploration as a potential treatment target for ADHD.

Lateral-Medial Dissociation in Orbitofrontal Cortex-Hypothalamus Connectivity

The orbitofrontal cortex (OFC) is involved in cognitive functions, and is also closely related to autonomic functions. The OFC is densely connected with the hypothalamus, a heterogeneous structure controlling autonomic functions that can be divided into two major parts: the lateral and the medial. Resting-state functional connectivity has allowed us to parcellate the cerebral cortex into putative functional areas based on the changes in the spatial pattern of connectivity in the cerebral cortex when a seed point is moved from one voxel to another. In the present high spatial-resolution fMRI study, we investigate the connectivity-based organization of the OFC with reference to the hypothalamus. The OFC was parcellated using resting-state functional connectivity in an individual subject approach, and then the functional connectivity was examined between the parcellated areas in the OFC and the lateral/medial hypothalamus. We found a functional double dissociation in the OFC: the lateral OFC (the lateral orbital gyrus) was more likely connected with the lateral hypothalamus, whereas the medial OFC (the medial orbital and rectal gyri) was more likely connected with the medial hypothalamus. These results demonstrate the fundamental heterogeneity of the OFC, and suggest a potential neural basis of the OFC–hypothalamic functional interaction.

Behavioral and autonomic reactivity to moral dilemmas in frontotemporal dementia versus Alzheimer's disease

The personal/impersonal distinction of moral decision-making postulates intuitive emotional responses from medial frontal activity and rational evaluation from lateral frontal activity. This model can be analyzed in behavioral variant frontotemporal dementia (bvFTD), a disorder characterized by impaired emotional intuitions, ventromedial prefrontal cortex (vmPFC) involvement, and relative sparing of lateral frontal regions. Moral dilemmas were presented to 10 bvFTD, 11 Alzheimer's disease (AD), and 9 healthy control (HC) participants while recording skin conductance responses, a measure of emotional arousal. We evaluated their personal versus impersonal conflict, subjective discomfort, and adherence to social norms. Replicating prior work, bvFTD participants were more willing to harm in the personal, but not the impersonal, dilemma compared to AD and HC groups. BvFTD participants had lower arousal and less of an increase in conflict on the personal versus the impersonal dilemma, in contrast to increased arousal and conflict for the AD and HC groups. Furthermore, bvFTD participants verbalized less discomfort, a correlate of low adherence to social norms. These findings support impaired emotional reactions to moral dilemmas in bvFTD and vmPFC lesions and the personal/impersonal model. It suggests a reversion to utilitarian-like considerations when emotional intuition is impaired in the brain.

Fear Memory

Fear memory is the best-studied form of memory. It was thoroughly investigated in the past 60 years mostly using two classical conditioning procedures (contextual fear conditioning and fear conditioning to a tone) and one instrumental procedure (one-trial inhibitory avoidance). Fear memory is formed in the hippocampus (contextual conditioning and inhibitory avoidance), in the basolateral amygdala (inhibitory avoidance), and in the lateral amygdala (conditioning to a tone). The circuitry involves, in addition, the pre- and infralimbic ventromedial prefrontal cortex, the central amygdala subnuclei, and the dentate gyrus. Fear learning models, notably inhibitory avoidance, have also been very useful for the analysis of the biochemical mechanisms of memory consolidation as a whole. These studies have capitalized on in vitro observations on long-term potentiation and other kinds of plasticity. The effect of a very large number of drugs on fear learning has been intensively studied, often as a prelude to the investigation of effects on anxiety. The extinction of fear learning involves to an extent a reversal of the flow of information in the mentioned structures and is used in the therapy of posttraumatic stress disorder and fear memories in general.