How to produce personality neuroscience research with high statistical power and low additional cost

MISPEL: A supervised deep learning harmonization method for multi-scanner neuroimaging data

Large-scale data obtained from aggregation of already collected multi-site neuroimaging datasets has brought benefits such as higher statistical power, reliability, and robustness to the studies. Despite these promises from growth in sample size, substantial technical variability stemming from differences in scanner specifications exists in the aggregated data and could inadvertently bias any downstream analyses on it. Such a challenge calls for data normalization and/or harmonization frameworks, in addition to comprehensive criteria to estimate the scanner-related variability and evaluate the harmonization frameworks. In this study, we propose MISPEL (Multi-scanner Image harmonization via Structure Preserving Embedding Learning), a supervised multi-scanner harmonization method that is naturally extendable to more than two scanners. We also designed a set of criteria to investigate the scanner-related technical variability and evaluate the harmonization techniques. As an essential requirement of our criteria, we introduced a multi-scanner matched dataset of 3T T1 images across four scanners, which, to the best of our knowledge is one of the few datasets of this kind. We also investigated our evaluations using two popular segmentation frameworks: FSL and segmentation in statistical parametric mapping (SPM). Lastly, we compared MISPEL to popular methods of normalization and harmonization, namely White Stripe, RAVEL, and CALAMITI. MISPEL outperformed these methods and is promising for many other neuroimaging modalities.

Improving the stability of bivariate correlations using informative Bayesian priors: a Monte Carlo simulation study

Objective

Much of psychological research has suffered from small sample sizes and low statistical power, resulting in unstable parameter estimates. The Bayesian approach offers a promising solution by incorporating prior knowledge into statistical models, which may lead to improved stability compared to a frequentist approach.

Methods

Simulated data from four populations with known bivariate correlations (ρ = 0.1, 0.2, 0.3, 0.4) was used to estimate the sample correlation as samples were sequentially added from the population, from n = 10 to n = 500. The impact of three different, subjectively defined prior distributions (weakly, moderately, and highly informative) was investigated and compared to a frequentist model.

Results

The results show that bivariate correlation estimates are unstable, and that the risk of obtaining an estimate that is exaggerated or in the wrong direction is relatively high, for sample sizes for below 100, and considerably so for sample sizes below 50. However, this instability can be constrained by informative Bayesian priors.

Conclusion

Informative Bayesian priors have the potential to significantly reduce sample size requirements and help ensure that obtained estimates are in line with realistic expectations. The combined stabilizing and regularizing effect of a weakly informative prior is particularly useful when conducting research with small samples. The impact of more informative Bayesian priors depends on one's threshold for probability and whether one's goal is to obtain an estimate merely in the correct direction, or to obtain a high precision estimate whose associated interval falls within a narrow range. Implications for sample size requirements and directions for future research are discussed.

Conscientiousness associated with efficiency of the salience/ventral attention network: Replication in three samples using individualized parcellation

Conscientiousness, and related constructs impulsivity and self-control, have been related to structural and functional properties of regions in the prefrontal cortex (PFC) and anterior insula. Network-based conceptions of brain function suggest that these regions belong to a single large-scale network, labeled the salience/ventral attention network (SVAN). The current study tested associations between conscientiousness and resting-state functional connectivity in this network using two community samples (N's = 244 and 239) and data from the Human Connectome Project (N = 1000). Individualized parcellation was used to improve functional localization accuracy and facilitate replication. Functional connectivity was measured using an index of network efficiency, a graph theoretical measure quantifying the capacity for parallel information transfer within a network. Efficiency of a set of parcels in the SVAN was significantly associated with conscientiousness in all samples. Findings are consistent with a theory of conscientiousness as a function of variation in neural networks underlying effective prioritization of goals.

Neural correlates of neuroticism: A coordinate-based meta-analysis of resting-state functional brain imaging studies

Neuroticism is one of the most robust higher-order personality traits associated with negative emotionality and risk of mental disorders. Many studies have investigated relationships between neuroticism and the brain, but the results have been inconsistent. We conducted a meta-analysis of whole-brain resting-state functional neuroimaging studies to identify the most stable neurofunctional substrates of neuroticism. We found stable significant positive correlations between neuroticism and resting-state brain activity in the left middle temporal gyrus (MTG), left striatum, and right hippocampus. In contrast, resting-state brain activity in the left superior temporal gyrus (STG) and right supramarginal gyrus (SMG) was negatively associated with neuroticism. Additionally, meta-regression analysis revealed brain regions in which sex and age moderated the link of spontaneous activity with neuroticism. This is the first study to provide a comprehensive understanding of resting-state brain activity correlates of neuroticism, and the findings may be useful for the targeting of specific brain regions for interventions to decrease the risks of mental health problems.

The relationship between brain neural correlates, self-objectification, and interoceptive sensibility

Interoceptive sensibility refers to the tendency to focus on internal bodily states and the capacity to detect them. As the subjective dimension of interoception, interoceptive sensibility plays a key role in individuals' health. Self-objectification, a process by which individuals tend to adopt a third-person's perspective of their physical self, leads to decreased interoceptive sensibility. However, few studies regarding the neural basis of interoceptive sensibility and the underlying mechanism of the relationship between self-objectification and interoceptive sensibility have been conducted. In this study, we assessed the resting-state brain activity (fractional amplitude of low-frequency fluctuation, fALFF) and connectivity (resting-state functional connectivity, RSFC) of 442 college students. Whole-brain correlation analyses revealed that a higher level of interoceptive sensibility was linked to higher fALFF in the right inferior frontal gyrus (IFG) and left cerebellum and to lower fALFF in the left paracentral lobule and left superior/middle temporal gyrus. Interoceptive sensibility also was negatively associated with the RSFC between the right IFG and the right secondary somatosensory cortex (S2) and the right IFG and the ventral premotor cortex (VPC). These brain regions and connections are mainly responsible for switching attention to internal/external information and processing body-related somatosensory as well as sensory information. Mediation analyses suggested that the fALFF of the right IFG and the RSFC of IFG-S2 and IFG-VPC mediated the relationship between self-objectification and interoceptive sensibility. Overall, these results suggest that the IFG may be the neural marker of interoceptive sensibility and reveal several potential mediation models of the relationship between brain neural correlates and self-objectification and interoceptive sensibility.

No trait anxiety influences on early and late differential neuronal responses to aversively conditioned faces across three different tasks

The human brain's ability to quickly detect dangerous stimuli is crucial in selecting appropriate responses to possible threats. Trait anxiety has been suggested to moderate these processes on certain processing stages. To dissociate such different information-processing stages, research using classical conditioning has begun to examine event-related potentials (ERPs) in response to fear-conditioned (CS +) faces. However, the impact of trait anxiety on ERPs to fear-conditioned faces depending on specific task conditions is unknown. In this preregistered study, we measured ERPs to faces paired with aversive loud screams (CS +) or neutral sounds (CS −) in a large sample (N = 80) under three different task conditions. Participants had to discriminate face-irrelevant perceptual information, the gender of the faces, or the CS category. Results showed larger amplitudes in response to aversively conditioned faces for all examined ERPs, whereas interactions with the attended feature occurred for the P1 and the early posterior negativity (EPN). For the P1, larger CS + effects were observed during the perceptual distraction task, while the EPN was increased for CS + faces when deciding about the CS association. Remarkably, we found no significant correlations between ERPs and trait anxiety. Thus, fear-conditioning potentiates all ERP amplitudes, some processing stages being further modulated by the task. However, the finding that these ERP differences were not affected by individual differences in trait anxiety does not support theoretical accounts assuming increased threat processing or reduced threat discrimination depending on trait anxiety.

Effects of task load, spatial attention, and trait anxiety on neuronal responses to fearful and neutral faces

There is an ongoing debate on how different components of the event-related potential (ERP) to threat-related facial expressions are modulated by attentional conditions and interindividual differences in trait anxiety. In the current study (N = 80), we examined ERPs to centrally presented, task-irrelevant fearful and neutral faces, while participants had to solve a face-unrelated visual task, which differed in difficulty and spatial position. Critically, we used a fixation-controlled experimental design and ensured the spatial attention manipulation by spectral analysis of the EEG. Besides the factors emotion, spatial attention, and perceptual load, we also investigated correlations between trait anxiety and ERPs. While P1 emotion effects were insignificant, the N170 was increased to fearful faces regardless of load and spatial attention conditions. During the EPN time window, a significantly increased negativity for fearful faces was observed only during low load and spatial attention to the face. We found no significant relationship between ERPs and trait anxiety, questioning the hypothesis of a general hypersensitivity toward fearful expressions in anxious individuals. These results show a high resistance of the N170 amplitude increase for fearful faces to spatial attention and task load manipulations. By contrast, the EPN modulation by fearful faces index a resource-dependent stage of the ERP, requiring both spatial attention at the location of faces and low load of the face-irrelevant task.

Neurocognitive aging data release with behavioral, structural and multi-echo functional MRI measures

Central to understanding human behavior is a comprehensive mapping of brain-behavior relations within the context of lifespan development. Reproducible discoveries depend upon well-powered samples of reliable data. We provide to the scientific community two, 10-minute, multi-echo functional MRI (ME-fMRI) runs, and structural MRI (T1-MPRAGE), from 181 healthy younger (ages 18-34 y) and 120 older adults (ages 60-89 y). T2-FLAIR MRIs and behavioral assessments are available in a majority subset of over 250 participants. Behavioral assessments include fluid and crystallized cognition, self-reported measures of personality, and socioemotional functioning. Initial quality control and validation of these data is provided. This dataset will be of value to scientists interested in BOLD signal specifically isolated from ME-fMRI, individual differences in brain-behavioral associations, and cross-sectional aging effects in healthy adults. Demographic and behavioral data are available within the Open Science Framework project "Goal-Directed Cognition in Older and Younger Adults" ( http://osf.io/yhzxe/ ), which will be augmented over time; neuroimaging data are available on OpenNeuro ( https://openneuro.org/datasets/ds003592 ).

Troubled past: A critical psychometric assessment of the self-report Survey of Autobiographical Memory (SAM)

The Survey of Autobiographical Memory (SAM) was designed as an easy-to-administer measure of self-perceived autobiographical memory (AM) recollection capacity. We provide a comprehensive psychometric evaluation of the SAM in younger and older adults. First, we evaluated the reliability of the SAM as a measure of self-perceived recollective capacity. Next, we tested whether the SAM was a valid measure of episodic and autobiographical memory performance, as assessed with widely used performance-based measures. Finally, we investigated associations between the SAM, cognitive measures and self-reported assessments of psychological functioning. The SAM demonstrated reliability as a self-report measure of perceived recollective capacity. High internal consistency was observed across subscales, with the exception of SAM-semantic. Evidence for independence among the subscales was mixed: SAM-episodic and SAM-semantic items showed poor correspondence with respective subscales. Good correspondence was observed between the future and spatial items and their SAM subscales. The SAM showed limited associations with AM performance as measured by the Autobiographical Interview (AI), yet was broadly associated with self-reported AI event vividness. SAM scores were weakly associated with performance-based memory measures and were age-invariant, inconsistent with known age effects on declarative memory. Converging evidence indicated that SAM-episodic and SAM-semantic subscales are not independent and should not be interpreted as specific measures of episodic or semantic memory. The SAM was robustly associated with self-efficacy, suggesting an association with confidence in domain general self-report abilities. We urge caution in the use and interpretation of the SAM as a measure of AM, pending revision and further psychometric validation.

Neurite density imaging in amygdala nuclei reveals interindividual differences in neuroticism

Neuroticism is known to have significant health implications. While previous research revealed that interindividual differences in the amygdala function are associated with interindividual differences in neuroticism, the impact of the amygdala’s structure and especially microstructure on variations in neuroticism remains unclear. Here, we present the first study using NODDI to examine the association between the in vivo microstructural architecture of the amygdala and neuroticism at the level of neurites. We, therefore, acquired brain images from 221 healthy participants using advanced multi‐shell diffusion‐weighted imaging. Because the amygdala comprises several nuclei, we, moreover, used a high‐resolution T1 image to automatically segment the amygdala into eight different nuclei. Neuroticism and its facets have been assessed using the NEO‐PI‐R. Finally, we associated neuroticism and its facets with the volume and microstructure of the amygdala nuclei. Statistical analysis revealed that lower neurite density in the lateral amygdala nucleus (La) was significantly associated with higher scores in depression, one of the six neuroticism facets. The La is the sensory relay of the amygdala, filtering incoming information based on previous experiences. Reduced neurite density and related changes in the dendritic structure of the La could impair its filtering function. This again might cause harmless sensory information to be misevaluated as threatening and lead to the altered amygdala responsivity as reported in previous studies investigating the functional correlates of neuroticism and neuroticism‐related disorders like depression.

Scan Once, Analyse Many: Using Large Open-Access Neuroimaging Datasets to Understand the Brain

We are now in a time of readily available brain imaging data. Not only are researchers now sharing data more than ever before, but additionally large-scale data collecting initiatives are underway with the vision that many future researchers will use the data for secondary analyses. Here I provide an overview of available datasets and some example use cases. Example use cases include examining individual differences, more robust findings, reproducibility-both in public input data and availability as a replication sample, and methods development. I further discuss a variety of considerations associated with using existing data and the opportunities associated with large datasets. Suggestions for further readings on general neuroimaging and topic-specific discussions are also provided.

Personality Neuroscience: An Emerging Field with Bright Prospects

Personality neuroscience is the study of persistent psychological individual differences, typically in the general population, using neuroscientific methods. It has the potential to shed light on the neurobiological mechanisms underlying individual differences and their manifestation in ongoing behavior and experience. The field was inaugurated many decades ago, yet has only really gained momentum in the last two, as suitable technologies have become widely available. Personality neuroscience employs a broad range of methods, including molecular genetics, pharmacological assays or manipulations, electroencephalography, and various neuroimaging modalities, such as magnetic resonance imaging and positron emission tomography. Although exciting progress is being made in this young field, much remains unknown. In this brief review, we discuss discoveries that have been made, methodological challenges and advances, and important questions that remain to be answered. We also discuss best practices for personality neuroscience research and promising future directions for the field.

Emotional intelligence mediates the association between middle temporal gyrus gray matter volume and social anxiety in late adolescence

As a common mental health problem, social anxiety refers to the fear and avoidance of interacting in social or performance situations, which plays a crucial role in many health and social problems. Although a growing body of studies has explored the neuroanatomical alterations related to social anxiety in clinical patients, far fewer have examined the association between social anxiety and brain morphology in the general population, which may help us understand the neural underpinnings of social anxiety more comprehensively. Here, utilizing a voxel-based morphometry approach via structural magnetic resonance imaging, we investigated brain gray matter correlates of social anxiety in 231 recent graduates of the same high school grade. We found that social anxiety was positively associated with gray matter volume in the right middle temporal gyrus (MTG), which is a core brain area for cognitive processing of emotions and feelings. Critically, emotional intelligence mediated the impact of right MTG volume on social anxiety. Notably, our results persisted even when controlling for the effects of general anxiety and depression. Altogether, our research reveals right MTG gray matter volume as a neurostructural correlate of social anxiety in a general sample of adolescents and suggests a potential indirect effect of emotional intelligence on the association between gray matter volume and social anxiety.

Behavioral and neural correlates of social network size: The unique and common contributions of face recognition and extraversion

OBJECTIVES

Humans are inherently social creatures and can gain advantages from larger network size. Researches have shown that different cognitive and personality factors may result in individual differences of social network size (SNS). Here, we focused on whether face recognition ability and extraversion were related to SNS and the neural basis underlying the relations.

METHODS

Behaviorally, we adopted the face-inversion task, NEO personality inventory, and computerized SNS test to explore the relationships between face recognition, extraversion, and SNS. Neurally, we used resting state functional magnetic resonance imaging and fractional amplitude of low-frequency fluctuation (fALFF) analysis method to investigate the neural correlates of SNS and then revealed whether face recognition and extraversion were related to SNS relevant brain regions.

RESULTS

We found that individuals with better face recognition ability and more extraverted personality had larger size of social network. In addition, we found that SNS was positively associated with the fALFF in the ventromedial prefrontal cortex (vmPFC), right superior temporal sulcus, and precuneus. Interestingly, the fALFF in the vmPFC significantly correlated with face recognition ability.

CONCLUSIONS

Our study suggests that both face recognition and extraversion may be important correlates of SNS, and the underlying spontaneous neural substrates are partially dissociable.

Sex-linked neurofunctional basis of psychological resilience in late adolescence: a resting-state functional magnetic resonance imaging study

Psychological resilience refers to the ability to adapt effectively in the face of adversity, which is closely related to an individual's psychological and physical health and well-being. Although previous behavioural studies have shown sex differences in psychological resilience, little is known about the neural basis of sex differences in psychological resilience. Here, we measured amplitude of low-frequency fluctuations (ALFF) via resting-state functional magnetic resonance imaging to investigate the sex-linked neurofunctional basis of psychological resilience in 231 healthy adolescents. At the behavioural level, we replicated previous findings indicating that males are more resilient than females. At the neural level, we found sex differences in the relationship between psychological resilience and ALFF in the right orbitofrontal cortex (OFC). Specifically, males showed a positive correlation between psychological resilience and ALFF in the right OFC, while females showed a negative correlation in this region. The sex-specific association between psychological resilience and spontaneous brain activity might be dependent on differences in hormonal systems and brain development between male and female adolescents. Taken together, the results of our study might provide the first evidence of sex-specific neurofunctional substrates of psychological resilience in adolescents, emphasizing the vital role of sex effects in future psychological resilience-related studies.

Neurostructural correlates of hope: dispositional hope mediates the impact of the SMA gray matter volume on subjective well-being in late adolescence

There has been increasing interest in identifying factors to predict subjective well-being in the emerging field of positive psychology over the past two decades. Dispositional hope, which reflects one's goal-directed tendencies, including both pathway thinking (planning to meet goals) and agency thinking (goal-directed determination), has emerged as a stable predictor for subjective well-being. However, the neurobiological substrates of dispositional hope and the brain-hope mechanism for predicting subjective well-being remain unclear. Here, we examined these issues in 231 high school graduates within the same grade by estimating cortical gray matter volume (GMV) utilizing a voxel-based morphometry method based on structural magnetic resonance imaging. Whole-brain regression analyses and prediction analyses showed that higher dispositional hope was stably associated with greater GMV in the left supplementary motor area (SMA). Furthermore, mediation analyses revealed that dispositional hope mediated the relation between left SMA volume and subjective well-being. Critically, our results were obtained after adjusting for age, sex, family socioeconomic status and total GMV. Altogether, our study presents novel evidence for the neuroanatomical basis of dispositional hope and suggests an underlying indirect effect of dispositional hope on the link between brain gray matter structure and subjective well-being.

Decoding personality trait measures from resting EEG: An exploratory report

Can personality be predicted from oscillatory patterns produced by the brain at rest? To date, relatively few studies using electroencephalography (EEG) have yielded consistent relations between personality trait measures and spectral power. Thus, new exploratory research may help develop targeted hypotheses about how neural processes associated with EEG activity may relate to personality differences. We used multivariate pattern analysis to decode personality scores (i.e., Big Five traits) from resting EEG frequency power spectra. Up to 8 minutes of EEG data was recorded per participant prior to completing an unrelated task (N = 168, M_age = 23.51, 57% female) and, in a subset of participants, after task completion (N = 96, M_age = 23.22, 52% female). In each recording, participants alternated between open and closed eyes. Linear support vector regression with 10-fold cross validation was performed using the power from 62 scalp electrodes within 1 Hz frequency bins from 1 to 30 Hz. One Big Five trait, agreeableness, could be decoded from EEG power ranging from 8 to 19 Hz, and this was consistent across all four recording periods. Neuroticism was decodable using data within the 3-6 Hz range, albeit less consistently. Posterior alpha power negatively correlated with agreeableness, whereas parietal beta power positively correlated with agreeableness. We suggest methods to draw from our results and develop targeted future hypotheses, such as linking to individual alpha frequency and incorporating self-reported emotional states. Our open dataset can be harnessed to reproduce results or investigate new research questions concerning the biological basis of personality.

Extracellular Vesicle-Mediated Delivery of Circular RNA SCMH1 Promotes Functional Recovery in Rodent and Nonhuman Primate Ischemic Stroke Models

BACKGROUND

Stroke is a leading cause of adult disability that can severely compromise the quality of life of patients, yet no effective medication currently exists to accelerate rehabilitation. A variety of circular RNA (circRNA) molecules are known to function in ischemic brain injury. Lentivirus-based expression systems have been widely used in basic studies of circRNAs, but safety issues with such delivery systems have limited exploration of the potential therapeutic roles for circRNAs.

METHODS

Circular RNA SCMH1 (circSCMH1) was screened from the plasma of patients with acute ischemic stroke by using circRNA microarrays. Engineered rabies virus glycoprotein-circSCMH1-extracellular vesicles were generated to selectively deliver circSCMH1 to the brain. Nissl staining was used to examine infarct size. Behavioral tasks were performed to evaluate motor functions in both rodent and nonhuman primate ischemic stroke models. Golgi staining and immunostaining were used to examine neuroplasticity and glial activation. Proteomic assays and RNA-sequencing data combined with transcriptional profiling were used to identify downstream targets of circSCMH1.

RESULTS

CircSCMH1 levels were significantly decreased in the plasma of patients with acute ischemic stroke, offering significant power in predicting stroke outcomes. The decreased levels of circSCMH1 were further confirmed in the plasma and peri-infarct cortex of photothrombotic stroke mice. Beyond demonstrating proof-of-concept for an RNA drug delivery technology, we observed that circSCMH1 treatment improved functional recovery after stroke in both mice and monkeys, and we discovered that circSCMH1 enhanced the neuronal plasticity and inhibited glial activation and peripheral immune cell infiltration. CircSCMH1 binds mechanistically to the transcription factor MeCP2 (methyl-CpG binding protein 2), thereby releasing repression of MeCP2 target gene transcription.

CONCLUSIONS

Rabies virus glycoprotein-circSCMH1-extracellular vesicles afford protection by promoting functional recovery in the rodent and the nonhuman primate ischemic stroke models. Our study presents a potentially widely applicable nucleotide drug delivery technology and demonstrates the basic mechanism of how circRNAs can be therapeutically exploited to improve poststroke outcomes.

Neurostructural correlates of optimism: Gray matter density in the putamen predicts dispositional optimism in late adolescence

Dispositional optimism reflects one's generalized positive expectancies for future outcomes and plays a crucial role in personal developmental outcomes and health (e.g., counteracting related mental disorders such as depression and anxiety). Increasing evidence has suggested that extraversion is an important personality factor contributing to dispositional optimism. However, less is known about the association between dispositional optimism and brain structure and the role of extraversion in this association. Here, we examined these issues in 231 healthy high school students aged 16 to 20 years (110 males, mean age = 18.48 years, SD = 0.54) by estimating regional gray matter density (rGMD) using a voxel-based morphometry method via structural magnetic resonance imaging. Whole-brain regression analyses revealed a significant positive correlation between dispositional optimism and the rGMD of the bilateral putamen after adjusting for age, sex, family socioeconomic status (SES), general intelligence, and total gray matter volume (TGMV). Moreover, prediction analyses using fourfold balanced cross-validation combined with linear regression confirmed a significant connection between dispositional optimism and putamen density after adjusting for age, sex, and family SES. More importantly, subsequent mediation analysis showed that extraversion may account for the association between putamen density and dispositional optimism after adjusting for age, sex, family SES, general intelligence, TGMV, and the other four Big Five personality traits. Taken together, the current study provides new evidence regarding the neurostructural basis underlying dispositional optimism in adolescents and underscores the importance of extraversion as an essential personality factor for dispositional optimism acquisition.

Amygdala volume and social anxiety symptom severity: Does segmentation technique matter?

The amygdala factors prominently in neurobiological models of social anxiety (SA), yet amygdala volume findings regarding SA have been inconsistent and largely focused on case-control characterization. One source of discrepant findings could be variability in volumetric techniques. Therefore, we compared amygdala volumes derived via an automated technique (Freesurfer) against a manually corrected approach, also involving Freesurfer. Additionally, we tested whether the relationship between volume and SA symptom severity would differ across volumetric techniques. We pooled participants (n = 76) from archival studies. SA severity was assessed with the Liebowitz Social Anxiety Scale; scores ranged from non-clinical to clinical levels. Freesurfer produced significantly larger amygdalar volumes for participants with poor image quality. Even after excluding such participants, paired sample t-tests showed Freesurfer's boundaries produced significantly larger amygdalar volumes than manually corrected ones, bilaterally. Yet, intra-class correlation coefficients between the two methods were high, which suggests that Freesurfer's over-estimation of amygdala volume was systemic. Regardless of segmentation technique, volumes were not associated with SA symptom severity. Potentially, amygdala sub-regions may yield clearer patterns regarding SA symptoms. Further, our study underscores the importance of image quality for segmentation of the amygdala, and image quality may be particularly valuable when examining anatomical data for subtle inter-individual differences.

Victim Sensitivity and Its Neural Correlates Among Patients With Major Depressive Disorder

BACKGROUND

Dysfunctional beliefs about the self are common in the development of depressive symptoms, but it remains unclear how depressed patients respond to unfair treatment, both dispositionally and neurally. The present research is an attempt to explore the differences in sensitivity to injustice as a victim and its neural correlates in patients with major depressive disorder (MDD) versus healthy controls.

METHODS

First episodic, drug-naïve patients with MDD (n = 30) and a control group (n = 30) were recruited to compare their differences in victim sensitivity. A second group of patients with MDD (n = 23) and their controls (n = 28) were recruited to replicate the findings and completed resting-state functional magnetic resonance imaging (fMRI) scanning. Spontaneous brain activity measured by fractional amplitude of low-frequency fluctuation (fALFF) was used to characterize the neural correlates of victim sensitivity both in patients and in healthy controls.

RESULTS

Higher victim sensitivity was consistently found in patients with MDD than healthy controls in both datasets. Multiple regression analysis on the fALFF showed a significant interaction effect between diagnosis and victim sensitivity in the right dorsolateral prefrontal cortex (DLPFC).

CONCLUSIONS

The patients with MDD show higher sensitivity to injustice as a victim, which may be independent of their disease course. The MDD patients differ from healthy controls in the neural correlates of victim sensitivity. These findings shed light on the linkage between cognitive control subserved by the DLPFC and negative bias towards the self implicated by higher victim sensitivity among the depressed patients.

The relationship among resting-state brain activity and connectivity, agreeableness and displaced aggression: Two possible mediation models

BACKGROUND

Displaced aggression is a specific form of attack prompted by rumination on anger experiences and revenge thought which might lead to expression of anger on innocent people. There is sufficient evidence demonstrating the potential role of agreeableness in reducing displaced aggression in theory. However, little is known about the neural basis of displaced aggression and how agreeableness and the underlying neural mechanisms link to displaced aggression.

METHODS

In this investigation, we examined these issues on 123 college students by assessing resting-state brain activity (i.e. amplitude of low-frequency fluctuation, ALFF) and connectivity (i.e. resting-state functional connectivity, RSFC).

RESULTS

Whole-brain correlation analysis revealed that a higher level of displaced aggression was linked with decreased ALFF in the left dorsomedial prefrontal cortex (dmPFC) and decreased RSFC between the left dmPFC and left ventromedial prefrontal cortex (vmPFC). Mediation analysis further revealed that left dmPFC activity and the left dmPFC-vmPFC connectivity mediated the relationship between agreeableness and displaced aggression, as well as agreeableness mediated the relation between left dmPFC activity and the left dmPFC-vmPFC connectivity and displaced aggression.

LIMITATIONS

Only ALFF and RSFC were used as indicators of brain function in this study. The two mediation models need to be further tested by longitudinal design or experimental methods in further studies.

CONCLUSIONS

This study suggested that dmPFC and vmPFC might be the functional neural markers of displaced aggression and provided two possible mediation models regarding the relationship among the resting-state brain activity and connectivity, agreeableness and displaced aggression.

Brain structure links trait conscientiousness to academic performance

In the long history of identifying factors to predict academic performance, conscientiousness, a so-called ‘big five’ personality trait describing self-regulation and goal-directed behavior, has emerged as a stable predictor for this purpose. However, the neuroanatomical substrates of trait conscientiousness and the underlying brain mechanism linking trait conscientiousness and academic performance are still largely unknown. Here, we examined these issues in 148 high school students within the same grade by estimating cortical gray matter volume (GMV) utilizing a voxel-based morphometry method based on structural magnetic resonance imaging. A whole-brain regression analysis showed that trait conscientiousness was positively associated with the GMV in the bilateral superior parietal lobe (SPL) and was negatively associated with the GMV in the right middle frontal gyrus (MFG). Furthermore, mediation analysis revealed that trait conscientiousness mediated the influences of the SPL and MFG volume on academic performance. Importantly, our results persisted even when we adjusted for general intelligence, family socioeconomic status and ‘big five’ personality traits other than conscientiousness. Altogether, our study suggests that the GMV in the frontoparietal network is a neurostructural marker of adolescents’ conscientiousness and reveals a potential brain-personality-achievement pathway for predicting academic performance in which gray matter structures affect academic performance through trait conscientiousness.

Stress and the brain: Perceived stress mediates the impact of the superior frontal gyrus spontaneous activity on depressive symptoms in late adolescence

Identifying factors for the prediction of depression is a long-standing research topic in psychiatry and psychology. Perceived stress, which reflects the tendency to appraise one's life situations as stressful and overwhelming, has emerged as a stable predictor for depressive symptoms. However, the neurobiological bases of perceived stress and how perceived stress influences depressive symptoms in the healthy brain remain largely unknown. Here, we investigated these issues in 217 healthy adolescents by estimating the fractional amplitude of low-frequency fluctuations (fALFFs) via resting-state functional magnetic resonance imaging. A whole-brain correlation analysis showed that higher levels of perceived stress were associated with greater fALFF in the left superior frontal gyrus (SFG), which is a core brain region for cognitive control and emotion regulation-related processes. Mediation analysis further indicated that perceived stress mediated the link between the fALFF in the left SFG and depressive symptoms. Importantly, our results remained significant even when excluding the influences of head motion, anxiety, SFG gray matter structure, and school environment. Altogether, our findings suggested that the fALFF in the left SFG is a neurofunctional marker of perceived stress in adolescents and revealed a potential indirect effect of perceived stress on the association between the SFG spontaneous activity and depressive symptoms.

Extraversion and reward-processing: Consolidating evidence from an electroencephalographic index of reward-prediction-error

Trait extraversion has been theorized to emerge from functioning of the dopaminergic reward system. Recent evidence for this view shows that extraversion modulates the scalp-recorded Reward Positivity, a putative marker of dopaminergic signaling of reward-prediction-error. We attempt to replicate this association amid several improvements on previous studies in this area, including an adequately-powered sample (N = 100) and thorough examination of convergent-divergent validity. Participants completed a passive associative learning task presenting rewards and non-rewards that were either predictable or unexpected. Frequentist and Bayesian analyses confirmed that the scalp recorded Reward Positivity (i.e., the Feedback-Related-Negativity contrasting unpredicted rewards and unpredicted non-rewards) was significantly associated with three measures of extraversion and unrelated to other basic traits from the Big Five personality model. Narrower sub-traits of extraversion showed similar, though weaker associations with the Reward Positivity. These findings consolidate previous evidence linking extraversion with a putative marker of dopaminergic reward-processing.

An attachment theoretical perspective for the neural representation of close others

Recent investigations in neuroscience elucidate the neural basis of close other cognitive representations, which serve functions central to our health and happiness. Yet, there are persistent barriers to this research, including disparate research methods and the absence of a common theoretical background. The present review connects neuroimaging and attachment theory within a novel social, cognitive and affective framework. We apply attachment theory to understand why we would expect cognitive representations of close others to be different from other social neural representations. Developing reliable markers of attachment is a critical step in mapping close other neural representations. We then examine existing neuroimaging literature on close other representations, highlighting the recruitment of neural systems supporting reward, motivation and distress alleviation, in addition to the mirror neuron system, default network and salience network. We then review the methodologies of past studies, revealing a diverse array of self-report measures assessing `closeness' and social cognitive tasks that, taken together, preclude meaningful synthesis of findings. Lastly, we discuss specific behavioral measures of attachment and closeness with recommendations for the field. This attachment framework integrates brain and behavioral sciences and unites theoretical principles with empirical methods to further our understanding of how the brain represents close others.

Personality variables modify the relationship between childhood maltreatment history and poor functional outcomes

Childhood maltreatment history is a prevalent risk factor for substance use disorder and has lifelong adverse consequences on psychiatric wellbeing. The role of personality variations in determining childhood maltreatment-associated outcomes is poorly understood. This study sought to test neuroticism and agreeableness as mediator and moderator, respectively, of functional outcomes associated with having a history of childhood maltreatment and presence/absence of cocaine dependence. Ninety-four participants completed the Structured Clinical Interview for DSM-IV (SCID-IV), Childhood Trauma Questionnaire (CTQ), NEO-Five Factor Inventory (NEO-FFI), and the Addiction Severity Index (ASI). The distribution-of-the-product strategy tested if neuroticism mediated the relationship between CTQ and ASI scores. Agreeableness was tested as a moderator using bootstrapped multiple regression analyses with agreeableness*CTQ interaction terms as predictors of ASI scores. Analyses covaried for cocaine dependence to determine its influence. Neuroticism mediated the relationship between severity of childhood maltreatment history and family (ASI-Family) and psychiatric (ASI-Psychiatric) dysfunction in adulthood, independent of cocaine dependence. Agreeableness negatively moderated the effect of childhood maltreatment severity on family dysfunction. Exposure to emotional neglect and abuse selectively drove the mediation and moderation effects. Personality-directed interventions that reduce neuroticism or increase agreeableness may be promising approaches to uncouple childhood maltreatment history from lifelong social and psychiatric dysfunction.

A distributed brain network predicts general intelligence from resting-state human neuroimaging data

Individual people differ in their ability to reason, solve problems, think abstractly, plan and learn. A reliable measure of this general ability, also known as intelligence, can be derived from scores across a diverse set of cognitive tasks. There is great interest in understanding the neural underpinnings of individual differences in intelligence, because it is the single best predictor of long-term life success. The most replicated neural correlate of human intelligence to date is total brain volume; however, this coarse morphometric correlate says little about function. Here, we ask whether measurements of the activity of the resting brain (resting-state fMRI) might also carry information about intelligence. We used the final release of the Young Adult Human Connectome Project (N = 884 subjects after exclusions), providing a full hour of resting-state fMRI per subject; controlled for gender, age and brain volume; and derived a reliable estimate of general intelligence from scores on multiple cognitive tasks. Using a cross-validated predictive framework, we predicted 20% of the variance in general intelligence in the sampled population from their resting-state connectivity matrices. Interestingly, no single anatomical structure or network was responsible or necessary for this prediction, which instead relied on redundant information distributed across the brain.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.

Resting-state functional brain connectivity best predicts the personality dimension of openness to experience

Personality neuroscience aims to find associations between brain measures and personality traits. Findings to date have been severely limited by a number of factors, including small sample size and omission of out-of-sample prediction. We capitalized on the recent availability of a large database, together with the emergence of specific criteria for best practices in neuroimaging studies of individual differences. We analyzed resting-state functional magnetic resonance imaging data from 884 young healthy adults in the Human Connectome Project (HCP) database. We attempted to predict personality traits from the "Big Five", as assessed with the NEO-FFI test, using individual functional connectivity matrices. After regressing out potential confounds (such as age, sex, handedness and fluid intelligence), we used a cross-validated framework, together with test-retest replication (across two sessions of resting-state fMRI for each subject), to quantify how well the neuroimaging data could predict each of the five personality factors. We tested three different (published) denoising strategies for the fMRI data, two inter-subject alignment and brain parcellation schemes, and three different linear models for prediction. As measurement noise is known to moderate statistical relationships, we performed final prediction analyses using average connectivity across both imaging sessions (1 h of data), with the analysis pipeline that yielded the highest predictability overall. Across all results (test/retest; 3 denoising strategies; 2 alignment schemes; 3 models), Openness to experience emerged as the only reliably predicted personality factor. Using the full hour of resting-state data and the best pipeline, we could predict Openness to experience (NEOFAC_O: r=0.24, R2=0.024) almost as well as we could predict the score on a 24-item intelligence test (PMAT24_A_CR: r=0.26, R2=0.044). Other factors (Extraversion, Neuroticism, Agreeableness and Conscientiousness) yielded weaker predictions across results that were not statistically significant under permutation testing. We also derived two superordinate personality factors ("α" and "β") from a principal components analysis of the NEO-FFI factor scores, thereby reducing noise and enhancing the precision of these measures of personality. We could account for 5% of the variance in the β superordinate factor (r=0.27, R2=0.050), which loads highly on Openness to experience. We conclude with a discussion of the potential for predicting personality from neuroimaging data and make specific recommendations for the field.

The optimistic brain: Trait optimism mediates the influence of resting-state brain activity and connectivity on anxiety in late adolescence

As a hot research topic in the field of psychology and psychiatry, trait optimism reflects the tendency to expect positive outcomes in the future. Consistent evidence has demonstrated the role of trait optimism in reducing anxiety among different populations. However, less is known about the neural bases of trait optimism and the underlying mechanisms for how trait optimism protects against anxiety in the healthy brain. In this investigation, we examined these issues in 231 healthy adolescent students by assessing resting-state brain activity (i.e., fractional amplitude of low-frequency fluctuations, fALFF) and connectivity (i.e., resting-state functional connectivity, RSFC). Whole-brain correlation analyses revealed that higher levels of trait optimism were linked with decreased fALFF in the right orbitofrontal cortex (OFC) and increased RSFC between the right OFC and left supplementary motor cortex (SMC). Mediation analyses further showed that trait optimism mediated the influence of the right OFC activity and the OFC-SMC connectivity on anxiety. Our results remained significant even after excluding the impact of head motion, positive and negative affect and depression. Taken together, this study reveals that fALFF and RSFC are functional neural markers of trait optimism and provides a brain-personality-symptom pathway for protection against anxiety in which fALFF and RSFC affect anxiety through trait optimism.

Widespread associations between trait conscientiousness and thickness of brain cortical regions

The neural correlates of human personality have been of longstanding interest; however, most studies in the field have relied on modest sample sizes and few replicable results have been reported to date. We investigated relationships between personality and brain gray matter in a sample of generally healthy, older (mean age 73 years) adults from Scotland drawn from the Lothian Birth Cohort 1936. Participants (N = 578) completed a brain MRI scan and self-reported Big Five personality trait measures. Conscientiousness trait scores were positively related to brain cortical thickness in a range of regions, including bilateral parahippocampal gyrus, bilateral fusiform gyrus, left cingulate gyrus, right medial orbitofrontal cortex, and left dorsomedial prefrontal cortex. These associations - most notably in frontal regions - were modestly-to-moderately attenuated by the inclusion of biomarker variables assessing allostatic load and smoking status. None of the other personality traits showed robust associations with brain cortical thickness, nor did we observe any personality trait associations with cortical surface area and gray matter volume. These findings indicate that brain cortical thickness is associated with conscientiousness, perhaps partly accounted for by allostatic load and smoking status.

Neuroanatomical correlates of grit: Growth mindset mediates the association between gray matter structure and trait grit in late adolescence

There is a long-standing interest in exploring the factors related to student achievement. As a newly explored personality trait, grit is defined as a person's tendency to pursue long-term goals with continual perseverance and passion, and grit plays a critical role in student achievement. Increasing evidence has shown that growth mindset, the belief that one's basic abilities are malleable and can be developed through effort, is a potential factor for cultivating grit. However, less is known about the association between grit and the brain and the role of growth mindset in this association. Here, we utilized voxel-based morphometry to examine the neuroanatomical correlates of grit in 231 healthy adolescent students by performing structural magnetic resonance imaging. The whole-brain regression analyses revealed that the regional gray matter volume (rGMV) in the left dorsolateral prefrontal cortex (DLPFC) negatively predicted grit. In contrast, the rGMV in the right putamen positively predicted grit. Furthermore, mediating analyses suggested that growth mindset served as a mediator in the association between left DLPFC volume and grit. Our results persisted even after controlling for the influences of self-control and delayed gratification. Overall, our study presents novel evidence for the neuroanatomical basis of grit and highlights that growth mindset might play an essential role in cultivating a student's grit level.

Grit and the brain: spontaneous activity of the dorsomedial prefrontal cortex mediates the relationship between the trait grit and academic performance

As a personality trait, grit involves the tendency to strive to achieve long-term goals with continual passion and perseverance and plays an extremely crucial role in personal achievement. However, the neural mechanisms of grit remain largely unknown. In this study, we aimed to explore the association between grit and the fractional amplitude of low-frequency fluctuations (fALFF) in 217 healthy adolescent students using resting-state functional magnetic resonance imaging (RS-fMRI). We found that an individual’s grit was negatively related to the regional fALFF in the right dorsomedial prefrontal cortex (DMPFC), which is involved in self-regulation, planning, goal setting and maintenance, and counterfactual thinking for reflecting on past failures. The results persisted even after the effects of general intelligence and the ‘big five’ personality traits were adjusted for. More importantly, the fALFF of the right DMPFC played a mediating role in the association between grit and academic performance. Overall, these findings reveal regional fALFF as a neural basis of grit and highlight the right DMPFC as a neural link between grit and academic performance.

Delay discounting is associated with the fractional amplitude of low-frequency fluctuations and resting-state functional connectivity in late adolescence

As a component of self-regulation, delay discounting (DD) refers to an individual’s tendency to prefer smaller-but-sooner rewards over larger-but-later rewards and plays an essential role in many aspects of human behavior. Although numerous studies have examined the neural underpinnings of DD in adults, there are far fewer studies focusing on the neurobiological correlates underlying DD in adolescents. Here, we investigated the associations between individual differences in DD and the fractional amplitude of low-frequency fluctuations (fALFF) and resting-state functional connectivity (RSFC) in 228 high school students using resting-state functional magnetic resonance imaging (RS-fMRI). At the regional level, we found an association between higher DD and greater fALFF in the dorsal anterior cingulate cortex (dACC), which is involved in conflict monitoring and strategy adaptation. At the connectivity level, DD was positively correlated with the RSFC between the dACC and the left dorsolateral prefrontal cortex (DLPFC), a critical functional circuit in the cognitive control network. Furthermore, these effects persisted even after adjusting for the influences of general intelligence and trait impulsivity. Overall, this study reveals the fALFF and RSFC as the functional brain basis of DD in late adolescents, aiding to strengthen and corroborate our understanding of the neural underpinnings of DD.

Examining gray matter structure associated with academic performance in a large sample of Chinese high school students

Achievement in school is crucial for students to be able to pursue successful careers and lead happy lives in the future. Although many psychological attributes have been found to be associated with academic performance, the neural substrates of academic performance remain largely unknown. Here, we investigated the relationship between brain structure and academic performance in a large sample of high school students via structural magnetic resonance imaging (S-MRI) using voxel-based morphometry (VBM) approach. The whole-brain regression analyses showed that higher academic performance was related to greater regional gray matter density (rGMD) of the left dorsolateral prefrontal cortex (DLPFC), which is considered a neural center at the intersection of cognitive and non-cognitive functions. Furthermore, mediation analyses suggested that general intelligence partially mediated the impact of the left DLPFC density on academic performance. These results persisted even after adjusting for the effect of family socioeconomic status (SES). In short, our findings reveal a potential neuroanatomical marker for academic performance and highlight the role of general intelligence in explaining the relationship between brain structure and academic performance.

Group-focused morality is associated with limited conflict detection and resolution capacity: Neuroanatomical evidence

Group-focused moral foundations (GMFs) - moral values that help protect the group's welfare - sharply divide conservatives from liberals and religiously devout from non-believers. However, there is little evidence about what drives this divide. Moral foundations theory and the model of motivated social cognition both associate group-focused moral foundations with differences in conflict detection and resolution capacity, but in opposing directions. Individual differences in conflict detection and resolution implicate specific neuroanatomical differences. Examining neuroanatomy thus affords an objective and non-biased opportunity to contrast these influential theories. Here, we report that increased adherence to group-focused moral foundations was strongly associated (whole-brain corrected) with reduced gray matter volume in key regions of the conflict detection and resolution system (anterior cingulate cortex and lateral prefrontal cortex). Because reduced gray matter is reliably associated with reduced neural and cognitive capacity, these findings support the idea outlined in the model of motivated social cognition that belief in group-focused moral values is associated with reduced conflict detection and resolution capacity.

Prosocial Personality Traits Differentially Predict Egalitarianism, Generosity, and Reciprocity in Economic Games

Recent research has highlighted the role of prosocial personality traits-agreeableness and honesty-humility-in egalitarian distributions of wealth in the dictator game. Expanding on these findings, we ran two studies to examine individual differences in two other forms of prosociality-generosity and reciprocity-with respect to two major models of personality, the Big Five and the HEXACO. Participants (combined N = 560) completed a series of economic games in which allocations in the dictator game were compared with those in the generosity game, a non-constant-sum wealth distribution task where proposers with fixed payoffs selected the size of their partner's payoff ("generosity"). We further examined positive and negative reciprocity by manipulating a partner's previous move ("reciprocity"). Results showed clear evidence of both generosity and positive reciprocity in social preferences, with allocations to a partner greater in the generosity game than in the dictator game, and greater still when a player had been previously assisted by their partner. There was also a consistent interaction with gender, whereby men were more generous when this was costless and women were more egalitarian overall. Furthermore, these distinct forms of prosociality were differentially predicted by personality traits, in line with the core features of these traits and the theoretical distinctions between them. HEXACO honesty-humility predicted dictator, but not generosity allocations, while traits capturing tendencies toward irritability and anger predicted lower generosity, but not dictator allocations. In contrast, the politeness-but not compassion-aspect of Big Five agreeableness was uniquely and broadly associated with prosociality across all games. These findings support the discriminant validity between related prosocial constructs, and have important implications for understanding the motives and mechanisms taking place within economic games.

Behavioral and neuronal determinants of negative reciprocity in the ultimatum game

The rejection of unfair offers in the ultimatum game (UG) indicates negative reciprocity. The model of strong reciprocity claims that negative reciprocity reflects prosociality because the rejecting individual is sacrificing resources in order to punish unfair behavior. However, a recent study found that the rejection rate of unfair offers is linked to assertiveness (status defense model). To pursue the question what drives negative reciprocity, the present study investigated individual differences in the rejection of unfair offers along with their behavioral and neuronal determinants. We measured fairness preferences and event-related potentials (ERP) in 200 healthy participants playing a computerized version of the UG with pictures of unfair and fair proposers. Structural equation modeling (SEM) on the behavioral data corroborated both the strong reciprocity and the status defense models of human cooperation: Not only more prosocial but also more assertive individuals were more likely to show negative reciprocity by rejecting unfair offers. Experimental ERP results confirmed the feedback negativity (FN) as a neural signature of fairness processing. Multilevel SEM of brain-behavior relationships revealed that negative reciprocity was significantly associated with individual differences in FN amplitudes in response to proposers. Our results confirm stable individual differences in fairness processing at the behavioral and neuronal level.