Structural and functional connectivity changes in the brain associated with shyness but not with social anxiety

Pre-COVID brain network topology prospectively predicts social anxiety alterations during the COVID-19 pandemic

Background

Social anxiety (SA) is a negative emotional response that can lead to mental health issues, which some have experienced during the coronavirus disease 2019 (COVID-19) pandemic. Little attention has been given to the neurobiological mechanisms underlying inter-individual differences in SA alterations related to COVID-19. This study aims to identify neurofunctional markers of COVID-specific SA development.

Methods

110 healthy participants underwent resting-state magnetic resonance imaging and behavioral tests before the pandemic (T1, October 2019 to January 2020) and completed follow-up behavioral measurements during the pandemic (T2, February to May 2020). We constructed individual functional networks and used graph theoretical analysis to estimate their global and nodal topological properties, then used Pearson correlation and partial least squares correlations examine their associations with COVID-specific SA alterations.

Results

In terms of global network parameters, SA alterations (T2-T1) were negatively related to pre-pandemic brain small-worldness and normalized clustering coefficient. In terms of nodal network parameters, SA alterations were positively linked to a pronounced degree centrality pattern, encompassing both the high-level cognitive networks (dorsal attention network, cingulo-opercular task control network, default mode network, memory retrieval network, fronto-parietal task control network, and subcortical network) and low-level perceptual networks (sensory/somatomotor network, auditory network, and visual network). These findings were robust after controlling for pre-pandemic general anxiety, other stressful life events, and family socioeconomic status, as well as by treating SA alterations as categorical variables.

Conclusions

The individual functional network associated with SA alterations showed a disrupted topological organization with a more random state, which may shed light on the neurobiological basis of COVID-related SA changes at the network level.

Resting-state causal connectivity of the bed nucleus of the stria terminalis in panic disorder

Panic disorder (PD) is associated with anticipatory anxiety, a sustained threat response that appears to be related to the bed nucleus of the stria terminalis (BNST). Individuals with panic disorder may demonstrate significant differences in causal connectivity of the BNST in comparison to healthy controls. To test this hypothesis, resting-state functional magnetic resonance imaging (fMRI) was used to identify aberrant causal connectivity of the BNST in PD patients. 19 PD patients and 18 healthy controls (HC) matched for gender, age and education were included. Granger causality analysis (GCA) utilizing the BNST as a seed region was used to investigate changes in directional connectivity. Relative to healthy controls, PD patients displayed abnormal directional connectivity of the BNST including enhanced causal connectivity between the left parahippocampal gyrus and left BNST, the right insula and the right BNST, the left BNST and the right dorsolateral prefrontal cortex (dlPFC) and right BNST to the left and right dlPFC. Furthermore, PD patients displayed weakened causal connectivity between the right dlPFC and the left BNST, the left dlPFC and the right BNST, the left BNST and the left dorsomedial prefrontal cortex (dmPFC), right insula, right fusiform, and right BNST to the right insula. The results suggest that PD strongly correlates with increased causal connectivity between emotional processing regions and the BNST and enhanced causal connectivity between the BNST and cognitive control regions.

Prenatal and postnatal maternal anxiety and amygdala structure and function in young children

Anxiety symptoms are relatively common during pregnancy and are associated with behavioural problems in children. The amygdala is involved in emotion regulation, and its volume and function are associated with exposure to prenatal maternal depression. The associations between perinatal maternal anxiety and children's amygdala structure and function remain unclear. The objective of this study was to determine associations between prenatal and postnatal maternal anxiety and amygdala structure and function in children. Maternal anxiety was measured during the second trimester of pregnancy and 12 weeks postpartum. T1-weighted anatomical data and functional magnetic resonance imaging data were collected from 54 children (25 females), between the ages of 3-7 years. Amygdala volume was calculated and functional connectivity maps were created between the amygdalae and the rest of the brain. Spearman correlations were used to test associations between amygdala volume/functional connectivity and maternal anxiety symptoms, controlling for maternal depression symptoms. Second trimester maternal anxiety symptoms were negatively associated with functional connectivity between the left amygdala and clusters in bilateral parietal regions; higher maternal anxiety was associated with increased negative connectivity. Postnatal maternal anxiety symptoms were positively associated with child amygdala volume, but this finding did not remain significant while controlling for total brain volume. These functional connectivity differences may underlie behavioral outcomes in children exposed to maternal anxiety during pregnancy.

Brain structure correlates of expected social threat and reward

Prospection (mentally simulating future events) generates emotionally-charged mental images that guide social decision-making. Positive and negative social expectancies-imagining new social interactions to be rewarding versus threatening-are core components of social approach and avoidance motivation, respectively. Interindividual differences in such positive and negative future-related cognitions may be underpinned by distinct neuroanatomical substrates. Here, we asked 100 healthy adults to vividly imagine themselves in a novel self-relevant event that was ambiguous with regards to possible social acceptance or rejection. During this task we measured participants' expectancies for social reward (anticipated feelings of social connection) or threat (anticipated feelings of rejection). On a separate day they underwent structural MRI; voxel-based morphometry was used to explore the relation between social reward and threat expectancies and regional grey matter volumes (rGMV). Increased rGMV in key default-network regions involved in prospection, socio-emotional cognition, and subjective valuation, including ventromedial prefrontal cortex, correlated with both higher social reward and lower social threat expectancies. In contrast, social threat expectancies uniquely correlated with rGMV of regions involved in social attention (posterior superior temporal sulcus, pSTS) and interoception (somatosensory cortex). These findings provide novel insight into the neurobiology of future-oriented cognitive-affective processes critical to adaptive social functioning.

Behavioral inhibition system and self-esteem as mediators between shyness and social anxiety

Shyness has been demonstrated to be an important factor associating with social anxiety. However, it is less clear on the mechanisms responsible for such association. The aim of the present study was to examine whether behavioral inhibition system (BIS) and self-esteem mediated the relationship between shyness and social anxiety. A sample of 521 healthy volunteers in the age range of 18-25 years completed self-report measures of BIS, self-esteem, shyness and social anxiety. Our correlational analyses showed that shyness was positively associated with social anxiety, supporting the overlapping and continuum hypotheses. Furthermore, BIS was positively correlated with shyness and social anxiety while self-esteem was negatively related to them, indicating that BIS and self-esteem were different in the relation between shyness and social anxiety. Importantly, results from structural equation modeling revealed that the relation between shyness and social anxiety was partially mediated by BIS and self-esteem, which suggested that they might play important roles in the relation between shyness and social anxiety.

Effects of subclinical depression, anxiety and somatization on brain structure in healthy subjects

BACKGROUND

Dimensional approaches in highly prevalent psychiatric disorders like depression or anxiety could lead to a better understanding of pathogenesis and advantages in early detection and prevention. In an effort to better understand associations of brain structural variation across the depression/anxiety spectra, we investigated minor subclinical symptoms in a non-clinical healthy population.

METHODS

We studied 177 healthy subjects from the community, who underwent high-resolution T1-weighted 3T MRI and completed the symptom-checklist-90 (SCL-90-R). Using voxel-based morphometry (VBM) analysis with CAT12 software, we correlated SCL-90-R-subscales for depression, anxiety, and somatization with gray matter across the brain.

RESULTS

Significant positive gray matter correlations emerged across all three scales in different areas: the depression subscale correlated positively with gray matter in the Rolandic operculum, superior temporal gyrus (left) and postcentral gyrus (bilateral), the anxiety subscale correlated positively with middle temporal gyrus, Rolandic operculum, middle cingular gyrus and precuneus bilaterally, and the somatization subscale with left inferior prefrontal cortex. Somatization also showed negative correlations with cerebellar vermis and right supplementary motor area.

LIMITATIONS

Our study is limited to VBM and does not include surface-based measures. It also only contains subjects with very small psychological distress by partly overlapping symptoms.

CONCLUSION

Our findings are consistent with a non-linear relationship between symptom severity and cortical volume in several brain areas involved in both emotion regulation as well as altered in clinically manifest depressive/anxiety disorders.

Intrinsic Brain Activity Responsible for Sex Differences in Shyness and Social Anxiety

Male and female show significant differences in important behavioral features such as shyness, yet the neural substrates of these differences remain poorly understood. Previous neuroimaging studies have demonstrated that both shyness and social anxiety in healthy subjects are associated with increased activation in the fronto-limbic and cognitive control areas. However, it remains unknown whether these brain abnormalities would be shared by different genders. Therefore, in the current study, we used resting-state fMRI (r-fMRI) to investigate sex differences in intrinsic cerebral activity that may contribute to shyness and social anxiety. Sixty subjects (28 males, 32 females) participated in r-fMRI scans, and the amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) were used to measure the spontaneous regional cerebral activity in all subjects. We first compared the differences between male and female both in the ALFF and fALFF and then we also examined the whole brain correlation between the ALFF/fALFF and the severity of shyness as well as social anxiety by genders. Referring to shyness measure, we found a significant positive correlation between shyness scores (CBSS) and ALFF/fALFF value in the frontoparietal control network and a negative correlation in the cingulo-insular network in female; while in male, there is no such correlation. For the social anxiety level, we found positive correlations between Leibowitz Social Anxiety Scale (LSAS) scores and spontaneous activity in the frontal-limbic network in male and negative correlation between the frontal-parietal network; however, such correlation was not prominent in female. This pattern suggests that shy female individuals engaged a proactive control process, driven by a positive association with activity in frontoparietal network and negative association in cingulo-insular network, whereas social anxiety males relied more on a reactive control process, driven by a positive correlation of frontal-limbic network and negative correlation of frontoparietal network. Our results reveal that shyness or social anxiety is associated with disrupted spontaneous brain activity patterns and that these patterns are influenced by sex.

Individual variation in the neural processes of motor decisions in the stop signal task: the influence of novelty seeking and harm avoidance personality traits

Personality traits contribute to variation in human behavior, including the propensity to take risk. Extant work targeted risk-taking processes with an explicit manipulation of reward, but it remains unclear whether personality traits influence simple decisions such as speeded versus delayed responses during cognitive control. We explored this issue in an fMRI study of the stop signal task, in which participants varied in response time trial by trial, speeding up and risking a stop error or slowing down to avoid errors. Regional brain activations to speeded versus delayed motor responses (risk-taking) were correlated to novelty seeking (NS), harm avoidance (HA) and reward dependence (RD), with age and gender as covariates, in a whole brain regression. At a corrected threshold, the results showed a positive correlation between NS and risk-taking responses in the dorsomedial prefrontal, bilateral orbitofrontal, and frontopolar cortex, and between HA and risk-taking responses in the parahippocampal gyrus and putamen. No regional activations varied with RD. These findings demonstrate that personality traits influence the neural processes of executive control beyond behavioral tasks that involve explicit monetary reward. The results also speak broadly to the importance of characterizing inter-subject variation in studies of cognition and brain functions.

Viewing the Personality Traits Through a Cerebellar Lens: a Focus on the Constructs of Novelty Seeking, Harm Avoidance, and Alexithymia

The variance in the range of personality trait expression appears to be linked to structural variance in specific brain regions. In evidencing associations between personality factors and neurobiological measures, it seems evident that the cerebellum has not been up to now thought as having a key role in personality. This paper will review the most recent structural and functional neuroimaging literature that engages the cerebellum in personality traits, as novelty seeking and harm avoidance, and it will discuss the findings in the context of contemporary theories of affective and cognitive cerebellar function. By using region of interest (ROI)- and voxel-based approaches, we recently evidenced that the cerebellar volumes correlate positively with novelty seeking scores and negatively with harm avoidance scores. Subjects who search for new situations as a novelty seeker does (and a harm avoiding does not do) show a different engagement of their cerebellar circuitries in order to rapidly adapt to changing environments. The emerging model of cerebellar functionality may explain how the cerebellar abilities in planning, controlling, and putting into action the behavior are associated to normal or abnormal personality constructs. In this framework, it is worth reporting that increased cerebellar volumes are even associated with high scores in alexithymia, construct of personality characterized by impairment in cognitive, emotional, and affective processing. On such a basis, it seems necessary to go over the traditional cortico-centric view of personality constructs and to address the function of the cerebellar system in sustaining aspects of motivational network that characterizes the different temperamental traits.

Fear of negative evaluation is associated with altered brain function in nonclinical subjects

Social anxiety disorder (SAD), which involves excessive anxiety and fear of negative evaluation, is accompanied by abnormalities in brain function. While social anxiety appears to be represented on a spectrum ranging from nonclinical behavior to clinical manifestation, neural alteration in nonclinical populations remains unclear. This study examined the relationship between psychological measures of social anxiety, mainly using the Fear of Negative Evaluation Scale (FNES), and brain function (functional connectivity, degree centrality, and regional betweenness centrality). Results showed that FNES scores and functional connectivity of the parahippocampal gyrus and orbitofrontal cortex and the betweenness centrality of the right parietal cortex were negatively correlated. These regions are altered in SAD patients, and each is associated with social cognition and emotional processing. The results supported the perspective that social anxiety occurs on a spectrum and indicated that the FNES is a useful means of detecting neural alterations that may relate to the social anxiety spectrum. In addition, the findings indicated that graph analysis was useful in investigating the neural underpinnings of SAD in addition to other psychiatric symptoms.

Gray matter abnormalities in patients with social anxiety disorder: A voxel-based morphometry study

The main objective of this study was to investigate the gray matter volume (GMV) differences between the patients with social anxiety disorder (SAD) and healthy controls, using VBM analysis. A total of 27 consecutive patients (15 women and 12 men) with SAD and 27 age and sex-matched healthy control subjects were included in this study. With magnetic resonance imaging, we examined GMV differences between SAD and healthy control groups. We found that GMV in the right middle and inferior temporal, left superior parietal, left precuneus and right fusiform areas were significantly greater in patients with SAD than in healthy controls. In addition, GMV in the right inferior and middle temporal regions were positively correlated with the social avoidance and total social anxiety scores of the participants in the SAD group. Lastly, greater GMV in the left superior parietal and precuneal regions were correlated with the higher disability in the social life of the patients with SAD. Our results suggest that the regions that showed significant GMV differences between the two groups play an important role in the pathophysiology of SAD and increased GMV in these regions might reflect a pathological process of neural abnormalities in this disorder.

Sex differences in intrinsic brain functional connectivity underlying human shyness

Shyness is a fundamental trait associated with social-emotional maladaptive behaviors, including many forms of psychopathology. Neuroimaging studies have demonstrated that hyper-responsivity to social and emotional stimuli occurs in the frontal cortex and limbic system in shy individuals, but the relationship between shyness and brain-wide functional connectivity remains incompletely understood. Using resting-state functional magnetic resonance imaging, we addressed this issue by exploring the relationship between regional functional connectivity strength (rFCS) and scores of shyness in a cohort of 61 healthy young adults and controlling for the effects of social and trait anxiety scores. We observed that the rFCS of the insula positively correlated with shyness scores regardless of sex. Furthermore, we found that there were significant sex-by-shyness interactions in the dorsal anterior cingulate cortex and insula (two core nodes of the salience network) as well as the subgenual anterior cingulate cortex: the rFCS values of these regions positively correlated with shyness scores in females but negatively correlated in males. Taken together, we provide evidence for intrinsic functional connectivity differences in individuals with different degrees of shyness and that these differences are sex-dependent. These findings might have important implications on the understanding of biological mechanisms underlying emotional and cognitive processing associated with shyness.

Altered gray matter density and disrupted functional connectivity of the amygdala in adults with Internet gaming disorder

OBJECTIVES

The aim of this study was to evaluate the altered brain structure and functional connectivity (FC) among subjects with Internet gaming disorder (IGD).

METHODS

We recruited 30 males with IGD and 30 controls and evaluated their gray matter density (GMD) and FC using resting fMRI. The severities of IGD, gaming urge, and impulsivity were also assessed.

RESULTS

The results demonstrated that the subjects with IGD had a higher impulsivity and a greater severity of IGD. The subjects with IGD had a lower GMD over the bilateral amygdala than the controls. Further, the subjects with IGD had lower FC with the left amygdala over the left dorsolateral prefrontal lobe (DLPFC) and with the right amygdala over the left DLPFC and orbital frontal lobe (OFL). They also had higher FC with the bilateral amygdala over the contralateral insula than the controls. The FC between the left amygdala and DLPFC was negatively correlated with impulsivity. The FC of the right amygdala to the left DLPFC and orbital frontal lobe was also negatively correlated with impulsivity. Our results indicated that the altered GMD over the amygdala might represent vulnerability to IGD, such as impulsivity. Further analysis of the amygdala demonstrated impaired FC to the frontal lobe, which represents impulsivity.

CONCLUSION

The results of this study suggested that the amygdala plays a very influential role in the mechanism of IGD. Its detailed role should be further evaluated in future study and should be considered in the treatment of IGD.

Alterations in amygdala functional connectivity reflect early temperament

Behavioral inhibition (BI) is a temperament identified early in life that is associated with increased risk for anxiety disorders. Amygdala hyperresponsivity, found both in behaviorally inhibited and anxious individuals, suggests that amygdala dysfunction may represent a marker of anxiety risk. However, broader amygdala networks have not been examined in individuals with a history of childhood BI. This study uses resting state fMRI to assess amygdala intrinsic functional connectivity (iFC) in 38 healthy young adults (19 with a history of BI, 19 with no history of BI) selected from a longitudinal study. Centromedial, basolateral, and superficial amygdala iFCs were compared between groups and examined in relation to self-report measures of anxiety. Group differences were observed in amygdala iFC with prefrontal cortex, striatum, anterior insula, and cerebellum. Adults characterized with BI in childhood endorsed greater state anxiety prior to entering the scanner, which was associated with several of the group differences. Findings support enduring effects of BI on amygdala circuitry, even in the absence of current psychopathology.

The alterations in inter-hemispheric functional coordination of patients with panic disorder: the findings in the posterior sub-network of default mode network

OBJECTIVE

Voxel-mirrored homotopic connectivity (VMHC) has been studied in several neuropsychiatric illnesses. The inter-hemispheric interactions probably could explain the important aspects for the pathophysiology of panic disorder (PD). Therefore, we initiated this study to estimate the differences in VMHC values between the PD patients and controls.

METHODS

Thirty first-episode medication-naïve patients with PD and 21 controls were enrolled with age and gender controlled. All the participants received the scanning of resting-state functional magnetic resonance imaging (R-FMRI). The R-FMRI images were preprocessed and analyzed to obtain the VMHC values. The two-sample t test of VMHC data between PD patients and controls was performed. We also explored the relationship between the VMHC values and clinical characteristics.

RESULTS

The controls had significantly higher VMHC values than patients in the posterior cingulate cortex and precuneus (false discovery rate corrected p<0.005). The one-sided results by the unilateral hemisphere mask also confirmed that the results were indeed found in the right hemisphere. The VMHC value in the posterior cingulate cortex was also negatively correlated with panic severity.

CONCLUSION

The alterations of inter-hemispheric coordination in cingulate-precuneus may play a role in the pathophysiology of PD.