Neurobiology of the structure of personality: dopamine, facilitation of incentive motivation, and extraversion

Extraversion modulates cortisol responses to acute social stress in chronic major depression

BACKGROUND

Chronic Major Depressive Disorder (CMDD) is a common, disabling illness that is often complicated by high reactivity to social stress. To further elucidate the nature of this reactivity, the current study evaluated whether the personality dimensions of neuroticism and extraversion influenced cortisol responses to a social challenge in CMDD patients vs. controls.

METHODS

Fifty participants with CMDD and 58 healthy controls completed the Trier Social Stress Test (TSST) using a standard protocol. Neuroticism and extraversion were measured using the Revised NEO Personality Inventory. Hierarchical linear regressions assessed associations between independent variables neuroticism and extraversion and dependent variable cortisol area-under-the-curve increase (AUCi) in response to the TSST in the two study groups.

RESULTS

The extraversion-by-group interaction was a significant predictor of cortisol AUCi, while no significant findings related to neuroticism were found. Simple slopes analysis revealed a significant negative association between extraversion and AUCi in the CMDD group, but not in healthy controls. Post-hoc analysis of the raw cortisol data over time found that CMDD participants with higher extraversion scores had significantly higher pre-challenge cortisol levels than did other study participants, however this did not explain or confound the AUCi results.

CONCLUSIONS

In participants with CMDD but not in controls, higher levels of extraversion were associated with higher pre-challenge cortisol levels and decreased cortisol reactivity during the TSST, however these two findings were statistically independent. These findings underline the importance of considering personality factors when studying stress biology in CMDD patients. Extraversion may prove to be an important intermediate target for both research and clinical work in this complex, heterogenous and often treatment-resistant population.

The Association Between Affective Temperament Traits and Dopamine Genes in Obese Population

Studies indicate the heritable nature of affective temperament, which shows personality traits predisposing to the development of mental disorders. Dopaminergic gene polymorphisms such as DRD4, COMTVal158Met, and DAT1 have been linked to affective disorders in obesity. Due to possible correlation between the aforementioned polymorphisms and the affective temperament, the aim of our research was to investigate this connection in an obese population. The study enrolled 245 obese patients (178 females; 67 males). The affective temperament was assessed using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego autoquestionnaire (TEMPS-A). Genetic polymorphisms of DAT1, COMTVal158Met and DRD4 were collected from peripheral blood sample and determined using a polymerase chain reaction (PCR). Only in COMT polymorphisms, the cyclothymic and irritable dimensions were significantly associated with Met/Val carriers (p = 0.04; p = 0.01). Another interesting finding was the correlation between the affective temperament and age in men and women. We assume that dopamine transmission in heterozygotes of COMT may determine the role of the affective temperament in obese persons. Dopaminergic transmission modulated by COMT may be responsible for a greater temperament expression in obese individuals. To our knowledge, this is the first study describing the role of affective temperament in the obese population, but more research is needed in this regard.

Structural correlates of the orbitofrontal cortex and amygdala and personality in female adolescents

The five-factor model consists of cognitive-affective-behavioral trait dimensions (neuroticism, extraversion, openness to experience, agreeableness, conscientiousness) that are central to models of psychopathology. In adults, individual differences in three of the Big Five traits, neuroticism, extraversion, and conscientiousness, have been linked to structural morphology and connectivity of the orbitofrontal cortex (OFC) and the amygdala, two brain regions critically involved in affective and regulatory processing. It is unclear whether these associations manifest in adolescence, a critical neurodevelopmental period during which many forms of psychiatric illness emerge. A total of 223 adolescent girls (ages 14-16 years) completed a multimodal neuroimaging study that utilized T1-weighted structural MRI (e.g., cortical thickness and volume) and tractography-based diffusion tensor imaging (64-direction). Cortical thickness and volume were extracted from the medial orbitofrontal cortex (mOFC) and amygdala and tractography-based fractional anisotropy was computed in the uncinate fasciculus (UF; the white matter tract connecting the OFC to the temporal lobe). We found that high neuroticism was associated with less mOFC volume (bilateral), and low conscientiousness was associated with higher white matter integrity in the UF, more amygdala volume, and less mOFC thickness (right hemisphere). Extraversion was not observed to share associations with OFC markers. These OFC-amygdala structural correlations to personality do not match those reported in adult samples. Multimodal neuroimaging techniques can help to clarify the underpinnings of personality development between adolescence and adulthood.

Mediating Effect of Trait Emotional Intelligence Between the Behavioral Activation System (BAS)/Behavioral Inhibition System (BIS) and Positive and Negative Affect

Gray (1970, 1981, 1987) proposed a behavioral motivation theory (Reinforcement Sensitivity Theory, RST), which describes the Behavioral Activation/Approach System (BAS) and the Behavioral Inhibition System (BIS). Some studies relate higher activation of BAS to positive affect, whereas BIS activation is linked to negative affect, particularly to high levels of anxiety and depression. Research data suggests that greater Trait Emotional Intelligence (TEI) influences optimal development of well-being and psychological adjustment, such as positive affective states. However, a recent study relates the motivational BIS/BAS systems with TEI, showing that high TEI is characterized by sensitivity to reward (BAS), and low TEI due to activation of the BIS system. The aim of this study was to explore how TEI may mediate the relationship between BIS/BAS sensitivity and positive and negative affect. Four-hundred and sixty-seven undergraduate students (385 females) were evaluated. TEI was evaluated with the Trait Meta-Mood Scale (TMMS). Affective states were measured with the Positive (PA) and Negative Affect (NA) Schedule, and BIS/BAS sensitivity was measured with The Sensitivity to Punishment (SP) and Sensitivity to Reward (SR) Questionnaire. The results reveal the influence of the two motivational systems on affective states, and show how this relationship is modified by and better explained through TEI. That is, a stronger approach to appetitive stimuli produces more positive affect, but a belief that one [does not] understand unpleasant emotions or that one analyzes them, or thinks that one cannot regulate or control emotions will reduce that positive state. Greater activation of inhibitory behaviors will produce greater negative affect, and this will increase when one perceives that one attends excessively to one's feelings or does not understand them or feels incapable of regulating them. Accordingly, although motivators could be a focus of interest for intervention, this study shows that the efficiency and profitability of these practical applications increases by adding TEI.

Resting Frontal Eeg Asymmetry and Personality Traits: A Meta–Analysis

Frontal asymmetry has been widely used as a marker of emotion, motivation, and psychopathology. When assessed during the resting state, it is regarded as an index of trait approach and withdrawal motivation. However, the replicability of these associations with personality is currently unclear. The present meta–analysis seeks to provide a comprehensive quantitative review of the relationship between personality traits and resting electroencephalographic (EEG) frontal asymmetry. We distinguished five personality clusters: extraversion, neuroticism, impulsivity, anger, and defensiveness. Data from 79 independent samples with overall 5700 participants were included in the meta–analysis. The results revealed that less than 0.4% of the variance in extraversion and neuroticism could be explained by resting frontal asymmetry. Similarly, a small effect was observed for trait anger, and a small–sized to medium–sized effect was observed for defensiveness, although the number of studies was very low. No significant effect emerged for impulsivity. The effects were further reduced after adjustment for publication bias. Given some evidence for heterogeneity, sub–traits were analysed, and methodological moderators were investigated. Based on the results, we conclude that the validity of resting frontal asymmetry as a marker for personality is not supported. Finally, recommendations are given to increase the replicability of frontal asymmetry research. © 2019 European Association of Personality Psychology

Social context effects on error-related brain activity are dependent on interpersonal and achievement-related traits

Brain correlates of performance monitoring, such as the Error-Related Negativity (ERN), are considerably influenced by situational factors. For instance, errors committed during social interaction typically elicit enhanced ERNs. While individual differences in ERN magnitude have been implicated in a wide variety of psychopathologies, it remains unclear how individual dispositions may interact with situational incentives to influence performance monitoring. Here, we analysed how interpersonal (Affiliation) and achievement-related (Agency) traits moderated the effects of interpersonal competition and interpersonal cooperation on the ERN. For this purpose, electroencephalography was collected from 78 participants while they performed a Flanker Task either in a competitive or in a cooperative social context (i.e., between-subjects design). We found that competition predicted enhanced error-related activity patterns compared to cooperation. Furthermore, participants who scored high in Affiliation elicited enhanced error-related activity. Conversely, high Agency scores were associated with reduced error-related activity, but this was only observed in the competitive context. These results indicate that the brain's response to error commission is not only sensitive to social incentives. Rather, the activity of the evaluative system that produces error signals appears to be crucially determined by the personal relevance of the incentives present in the context in which performance is evaluated.

Circadian modulation of human reward function: Is there an evidentiary signal in existing neuroimaging studies?

Reward functioning in animals is modulated by the circadian system, but such effects are poorly understood in the human case. The aim of this study was to address this deficit via a systematic review of human fMRI studies measuring one or more proxies for circadian function and a neural reward outcome. A narrative synthesis of 15 studies meeting inclusion criteria identified 13 studies that show a circadian impact on the human reward system, with four types of proxy (circadian system biology, downstream circadian rhythms, circadian challenge, and time of day) associated with neural reward activation. Specific reward-related regions/networks subserving this effect included the medial prefrontal cortex, ventral striatum, putamen and default mode network. The circadian effect was observed in measures of both reward anticipation and reward receipt, with more consistent evidence for the latter. Findings are limited by marked heterogeneity across study designs. We encourage a systematic program of research investigating circadian-reward interactions as an adapted biobehavioural feature and as an aetiological mechanism in reward-related pathologies.

Food or money? Children's brains respond differently to rewards regardless of weight status

BACKGROUND

Brain responses to both food and monetary rewards have been linked to weight gain and obesity in adults, suggesting that general sensitivity to reward contributes to overeating. However, the relationship between brain reward response and body weight in children is unclear.

OBJECTIVE

The objective of this study was to assess the brain's response to multiple rewards and the relationship to body weight in children.

METHODS

We tested this by performing functional magnetic resonance imaging while children (7- to 11-years-old; healthy weight [n = 31], overweight/obese [n = 30]) played a modified card-guessing task to assess blood-oxygen-level-dependent (BOLD) response to anticipating and winning food and money rewards. Functional magnetic resonance imaging data were analysed using a region of interest and exploratory whole-brain approach.

RESULTS

Region of interest results demonstrated increased BOLD response in the striatum to anticipating food vs. neutral (control) and winning money vs. neutral. Whole-brain data showed that winning money vs. food was associated with increased activation in the striatum, as well as regions associated with cognitive control and emotion. Notably, for both approaches, these effects were independent of child weight status. Additionally, children's reported food responsiveness and emotional overeating were negatively correlated with the BOLD response in the left cingulate gyrus for winning food vs. money.

CONCLUSION

Overall, findings from this study show that regions associated with reward, cognitive control and emotion may play a role in the brain's response to food and money rewards, independently of how much the child weighs. These findings provide insight into reward sensitivity in children, which may have implications for understanding overeating and the development of obesity.

Greater tolerance to losses in sensation seeking: Evidence from probability and delay discounting

BACKGROUND

Sensation seeking is a behavioral endophenotype of substance use and is associated with abnormalities in financial reward processing. Previous research suggests that high sensation seekers (HSS) relative to low sensation seekers (LSS) show either an enhanced sensitivity to financial rewards or a reduced sensitivity to financial punishments. However, there are few studies investigating the valuation of financial rewards and punishments as a function of delivery probability and delay, two important aspects of reward processing that influence the valuation.

METHODS

We administrated a probability discounting task and a delay discounting task to 56 HSS and 57 LSS selected from a large sample. Each task was crossed with two factors: valence (gain vs. loss) and amount (Ұ1000 vs. Ұ50000).

RESULTS

For the probability discounting task, HSS discounted probabilistic losses but not gains more steeply than LSS, irrespective of the amount of outcome. For the delay discounting task, HSS discounted delayed losses more steeply than LSS, for the large but not small amount condition. In contrast, both groups exhibited comparable discounting rates for gains across the two amount conditions. These results remained significant when impulsivity levels were controlled for.

CONCLUSIONS

Together, our data strengthen the argument that the dysfunctional valuation in sensation seeking is valence specific, which may be driven by a weaker avoidance system, rather than by a stronger approach system.

Dopamine: Functions, Signaling, and Association with Neurological Diseases

The dopaminergic system plays important roles in neuromodulation, such as motor control, motivation, reward, cognitive function, maternal, and reproductive behaviors. Dopamine is a neurotransmitter, synthesized in both central nervous system and the periphery, that exerts its actions upon binding to G protein-coupled receptors. Dopamine receptors are widely expressed in the body and function in both the peripheral and the central nervous systems. Dopaminergic signaling pathways are crucial to the maintenance of physiological processes and an unbalanced activity may lead to dysfunctions that are related to neurodegenerative diseases. Unveiling the neurobiology and the molecular mechanisms that underlie these illnesses may contribute to the development of new therapies that could promote a better quality of life for patients worldwide. In this review, we summarize the aspects of dopamine as a catecholaminergic neurotransmitter and discuss dopamine signaling pathways elicited through dopamine receptor activation in normal brain function. Furthermore, we describe the potential involvement of these signaling pathways in evoking the onset and progression of some diseases in the nervous system, such as Parkinson's, Schizophrenia, Huntington's, Attention Deficit and Hyperactivity Disorder, and Addiction. A brief description of new dopaminergic drugs recently approved and under development treatments for these ailments is also provided.

Integrating Preclinical and Clinical Models of Negative Urgency

Overwhelming evidence suggests that negative urgency is robustly associated with rash, ill-advised behavior, and this trait may hamper attempts to treat patients with substance use disorder. Research applying negative urgency to clinical treatment settings has been limited, in part, due to the absence of an objective, behavioral, and translational model of negative urgency. We suggest that development of such a model will allow for determination of prime neurological and physiological treatment targets, the testing of treatment effectiveness in the preclinical and the clinical laboratory, and, ultimately, improvement in negative-urgency-related treatment response and effectiveness. In the current paper, we review the literature on measurement of negative urgency and discuss limitations of current attempts to assess this trait in human models. Then, we review the limited research on animal models of negative urgency and make suggestions for some promising models that could lead to a translational measurement model. Finally, we discuss the importance of applying objective, behavioral, and translational models of negative urgency, especially those that are easily administered in both animals and humans, to treatment development and testing and make suggestions on necessary future work in this field. Given that negative urgency is a transdiagnostic risk factor that impedes treatment success, the impact of this work could be large in reducing client suffering and societal costs.

Predictive Validity of the Three-Factor Model of Impulsivity for Risky Behaviors

Impulsivity is a multifaceted construct particularly relevant for understanding a wide variety of behaviors, especially risky behaviors. A recent conceptualization of impulsivity identifies three impulsivity factors-pervasive influence of feelings, feelings trigger action, and lack of follow-through-that have been shown to predict different behaviors. In this contribution, we examine the psychometric properties of an Italian version of such a three-factor model on a relatively large sample (N = 845). Moreover, on a subsample (n = 766) we determined whether specific dimensions of impulsivity are related to a series of risky behaviors, assessed 3 weeks later, by testing the predictive validity of the multidimensional inventory also in comparison with a standard measure of personality (HEXACO). An exploratory structural equation model confirmed the original 3-dimension structure and showed that the Italian adaptation has satisfactory psychometric properties. Convergent validity with the HEXACO dimensions was established. Furthermore, only the factors feelings trigger action and lack of follow-through, not pervasive influence of feelings, predicted risky behaviors. Findings provide a clear support to the 3-factor model of impulsivity and demonstrate its usefulness for a better comprehension of risky behaviors.

Achievement motivation in early schizophrenia: Relationship with symptoms, cognition and functional outcome

BACKGROUND

Individuals with schizophrenia engage in goal-directed activities significantly less often compared to healthy individuals in the community. There is ample evidence documenting the presence of motivational deficits in schizophrenia using observer-based ratings; however, purely self-reported accounts of patients' motivation are less well understood. This study examined subjective accounts of trait achievement motivation among relatively young, clinically stable, early-course outpatients with schizophrenia.

METHODS

Thirty-nine early-course patients and 39 healthy comparison subjects completed clinical and cognitive assessments in addition to a self-report inventory measuring achievement motivation.

RESULTS

Patients were found to endorse significantly lower levels of motivation, a mean difference which translated to a large effect size (Cohen's d = 1.1). Patients' self-reported motivation was significantly related to clinician ratings of motivational deficits which were based on behavioural output, and to vocational functioning. Within the patient sample, 33.3% of individuals were found to experience prominent or clinically significant levels of amotivation based on patients' own self-report. Self-reported achievement motivation was not associated with other clinical variables such as positive symptom severity or expressive negative symptoms.

CONCLUSIONS

Our results serve to highlight the occurrence and prevalence of motivational deficits in patients with schizophrenia who are in the early stages of their illness. Subjective accounts of motivation in this population were found to be related to important outcomes such as community functioning, highlighting the importance of this domain of illness. Targeting these deficits early in the course of the illness offers the potential to curb potential prospective poor outcomes and sets the stage for recovery.

Impulsive reactivity to emotion and vulnerability to psychopathology

Impulsiveness has been studied as an aspect of personality and psychopathology for generations. There are longstanding disagreements about how to define it and whether it should be viewed as one construct or several. This article begins by briefly reviewing some earlier and some more recent work on impulsiveness. Several approaches have recently converged to focus on a distinction between impulsive reactions to emotion and impulsive properties that are not initiated by emotion. From this review, we turn to psychopathology. It is well known that impulsiveness is related to externalizing psychopathology, but some have concluded that a similar relation does not exist for internalizing psychopathology. A recent literature is described that challenges the latter conclusion, linking impulsive reactivity to emotion to both externalizing and internalizing aspects of psychopathology. Discussion then turns to emotion-related impulsiveness and other constructs to which it is conceptually and empirically related, reexamining whether other conceptual targets should be added to the discussion. The article closes with a consideration of how important it is to continue to remain open to new conceptual perspectives. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Maternal Parenting Stress, Child Exuberance, and Preschoolers' Behavior Problems

This study investigated whether child exuberance, an aspect of temperament related to emotion regulation, moderates the well-documented association between high parenting stress and increased risk for internalizing and externalizing problems during the preschool years. At 42 months of age child exuberance was observed in 256 children (47% girls) and maternal self-reports on parenting stress were obtained. At 48 months internalizing and externalizing problems were assessed through reports from both parents. Indeed, higher maternal parenting stress increased the risk for internalizing problems, and this association was more pronounced among children with high levels of exuberance. Existent emotion regulation difficulties in highly exuberant children may further heighten the risk conveyed by an unfavorable caregiving environment for developing internalizing problems.

Prenatal influences on temperament development: The role of environmental epigenetics

This review summarizes current knowledge and outlines future directions relevant to questions concerning environmental epigenetics and the processes that contribute to temperament development. Links between prenatal adversity, epigenetic programming, and early manifestations of temperament are important in their own right, also informing our understanding of biological foundations for social-emotional development. In addition, infant temperament attributes represent key etiological factors in the onset of developmental psychopathology, and studies elucidating their prenatal foundations expand our understanding of developmental origins of health and disease. Prenatal adversity can take many forms, and this overview is focused on the environmental effects of stress, toxicants, substance use/psychotropic medication, and nutrition. Dysregulation associated with attention-deficit/hyperactivity-disruptive disorders was noted in the context of maternal substance use and toxicant exposures during gestation, as well as stress. Although these links can be made based on the existing literature, currently few studies directly connect environmental influences, epigenetic programming, and changes in brain development/behavior. The chain of events starting with environmental inputs and resulting in alterations to gene expression, physiology, and behavior of the organism is driven by epigenetics. Epigenetics provides the molecular mechanism of how environmental factors impact development and subsequent health and disease, including early brain and temperament development.

Revisiting the form and function of conflict: Neurobiological, psychological, and cultural mechanisms for attack and defense within and between groups

Conflict can profoundly affect individuals and their groups. Oftentimes, conflict involves a clash between one side seeking change and increased gains through victory and the other side defending the status quo and protecting against loss and defeat. However, theory and empirical research largely neglected these conflicts between attackers and defenders, and the strategic, social, and psychological consequences of attack and defense remain poorly understood. To fill this void, we model (1) the clashing of attack and defense as games of strategy and reveal that (2) attack benefits from mismatching its target's level of defense, whereas defense benefits from matching the attacker's competitiveness. This suggests that (3) attack recruits neuroendocrine pathways underlying behavioral activation and overconfidence, whereas defense invokes neural networks for behavioral inhibition, vigilant scanning, and hostile attributions; and that (4) people invest less in attack than defense, and attack often fails. Finally, we propose that (5) in intergroup conflict, out-group attack needs institutional arrangements that motivate and coordinate collective action, whereas in-group defense benefits from endogenously emerging in-group identification. We discuss how games of attack and defense may have shaped human capacities for prosociality and aggression, and how third parties can regulate such conflicts and reduce their waste.

Resting Frontal Asymmetry and Reward Sensitivity Theory Motivational Traits

The revised reinforcement sensitivity theory (rRST) of personality has conceptualized three main systems: the behavioural approach system (BAS), behavioural inhibition system (BIS), and fight-flight-freeze system (FFFS). Research links greater relative left-frontal activity with BAS-related tendencies and impulsivity and greater relative right-frontal activity with "withdrawal" motivation that included both BIS and FFFS. Although rRST has addressed the separation of FFFS and BIS, much of personality neuroscience research does not indicate which system is related to right frontal activity. We administered the Reinforcement Sensitivity Theory of Personality Questionnaire (RST-PQ) to measure the BAS and its facets (goal-drive persistence, reward interest, reward reactivity, and impulsivity), BIS, and the withdrawal FFFS. We examined the association of RST-PQ traits with resting electroencephalogram (EEG) alpha-asymmetry in female participants (N = 162) by considering the influence of experimenter's gender. In the total group, that included two subgroups with experimenters of different gender, BAS-impulsivity was related to greater left- than right-frontal activity, and FFFS, but not BIS, was related to greater relative right-frontocentral activity. These associations remained significant for the subgroup with a young same-sex experimenter, but not with opposite-sex experimenter.

Interpersonal Dynamics in Personality and Personality Disorders

Clinical and basic personality psychologists interact less than they should, given their similar interests. In clinical personality psychology, available evidence supports a transition from the current categorical system to a hierarchical trait scheme for diagnosing the stable features of personality disorder. However, trait models do not capture the dynamic aspects of personality disorders as they have been described in the clinical literature, and thus miss a clinically critical feature of personality pathology. In contrast, basic personality psychologists have coalesced around a consensual structure of individual differences and become increasingly interested in the dynamic processes that underlie and contextualize traits. But trait psychology models are not sufficiently specific to characterize dynamic personality processes. In this paper, I filter clinical descriptions of personality disorders through the lens of interpersonal theory to specify a recursive within–situation interpersonal pattern of motives, affects, behaviours, and perceptions that could contribute to the stable between–situation patterns of maladaptive behaviour of historical interest to both basic and clinical personality psychologists. I suggest that this interpersonal model adds specificity to recent proposals regarding processes in the basic personality literature and has significant potential to advance research on personality dynamics. © 2018 European Association of Personality Psychology

Reward Responsivity in Parenting: Development of a Novel Measure in Mothers of Young Children

The purpose of the current study was to develop and evaluate a measure of maternal reward responsivity in parenting. Deficits in reward responsivity, a common feature of depression, may contribute to maladaptive parenting behaviors. Reward responsivity is an individual difference in reactivity to pleasurable stimuli and represents a key motivational component that could contribute to the frequency and quality of mothers' interactions with their infants. However, there is currently no measure of reward responsivity in parenting, which would be necessary to evaluate the link between mother reward responsivity, behaviors towards their infant, and infant behavior. Therefore, the current study reports on the development and initial evaluation of a self-report measure of reward responsivity in parenting, the Mother Inventory of Reward Experience (MIRE). We evaluated the MIRE among 200 mothers (M =28.45, SD = 5.50) recruited from a pediatric primary care center. After item analysis, 22 items were retained and displayed high internal consistency reliability and test re-test reliability. Convergent validity was established via a significant correlation with global reward responsivity. Concurrent validity was established via significant correlations with depressive symptoms, parenting stress, and child behavior problems. Incremental validity of the MIRE over a measure of global reward responsivity was supported. These results support the reliability and validity of the MIRE as a measure of reward responsivity in parenting.

The Role of Resilience in Internet Addiction among Adolescents between Sexes: A Moderated Mediation Model

The behavioral inhibition/activation systems (BIS/BAS) have been considered to be predictors of Internet addiction, mediated by clinical variables such as anxiety and depression. However, resilience has been suggested as a protective factor toward Internet addiction, and certain sex differences in resilience buffering the effects of vulnerability have been reported. Thus, the aim of this study was to identify any role of resilience that might moderate the effects of BIS/BAS on Internet addiction through multiple clinical variables in boys and girls. A total of 519 middle-school students (268 boys and 251 girls, all 14 years old) were administered a questionnaire battery that measures Internet addiction, BIS/BAS, depression, anxiety, impulsivity, anger, and resilience. We used the PROCESS macro in SPSS to perform moderation and mediation analysis. Findings revealed that although a somewhat similar mediation model was supported in both sexes, moderating effects of resilience only emerged in girls. The results showed a protective role of resilience differing between sexes. These results suggest that clinicians should consider sex in the way resilience works as a protective factor against Internet addiction and focus on mitigating the effects of vulnerability by enhancing resilience in female Internet addicts.

Some Metatheoretical Principles for Personality Neuroscience

Theories in personality neuroscience must aim to be consistent with several levels of explanation. If we view personality traits as constructs located only at the psychological level, we must still make their explanations compatible with observations and theories at lower levels, particularly with what we know at the neural level. If we view personality traits as constructs located only at the neural level, we will still need to predict their emergent effects at the psychological level. Personality theory at present treats traits as psychological-level constructs, with even the recent neurally oriented Cybernetic Big Five Theory specified in terms of a "conceptual nervous system" and not requiring complete or immediate translation into neural mechanisms. Here, we argue for the existence of phylogenetically old, neural-level traits that are substantially conserved across many vertebrate species. We first ask what known mechanisms control trait-like properties of neural systems: Focusing on hormones, the GABAA receptor, and amine neurotransmitter systems. We derive from what we know about these sources of neuronal modulation some metatheoretical principles to guide the future development of those aspects of personality theory, starting with neural-level trait constructs and drawing implications for higher-level trait psychology observations. Current descriptive approaches such as the Big Five are an essential precursor to personality neuroscience, but may not map one-to-one to the mechanisms and constructs of a neuroscience-based approach to traits.

The Virtual Personalities Neural Network Model: Neurobiological Underpinnings

The Virtual Personalities Model is a motive-based neural network model that provides both a psychological model and a computational implementation that explicates the dynamics and often large within-person variability in behavior that arises over time. At the same time the same model can produce -- across many virtual personalities - between subject variability in behavior that when factor analyzed yields familiar personality structure (e.g., the Big-5). First, we describe our personality model and its implementation as a neural network model. Second, we focus on detailing the neurobiological underpinnings of this model. Third, we examine the learning mechanisms, and their biological substrates, as ways that the model gets "wired up", discussing Pavlovian and instrumental conditioning, Pavlovian to instrumental transfer (PIT), and habits. Finally, we describe the dynamics of how initial differences in propensities (e.g., dopamine functioning), wiring differences due to experience, and other factors could operate together to develop and change personality over time, and how this might be empirically examined. Thus, our goal is to contribute to the rising chorus of voices seeking a more precise neurobiologically-based science of the complex dynamics underlying personality.

Extraversion and behavioural approach system in stimulus analysis and motor response initiation

In this study, we attempt to validate previous findings on extraversion-related differences in speed of sensorimotor processing and to extend them into Behavioural Approach System (BAS) subtraits within the framework of the revised Reinforcement Sensitivity Theory (rRST) of personality. Here, we assessed psychological traits of extraversion (E), four BAS facets (Goal-Drive Persistence, BAS-GDP; Reward Interest, BAS-RI; Reward Reactivity, BAS-RR; Impulsivity, BAS-I), Behavioural Inhibition System (BIS), and Fight-Flight-Freeze System (FFFS) in 51 volunteers (28 women). Stimulus-locked lateralized readiness potential (S-LRP), response-locked LRP (R-LRP), stimulus-locked and response-locked forearm electromyogram (S-EMG and R-EMG), and P3 components of the event-related potentials (ERPs), were recorded during the performance of a two-choice Go/NoGo visual letter-digit discrimination task varying in task difficulty. High extraverts, relative to introverts and individuals high relative to low on BAS-RI, were more likely to exhibit shorter S-LRP latencies and stimulus- and response-locked EMG latencies. Additionally, high BAS-I had a shorter R-RLP latency than low BAS-I participants for the difficult task. High FFFS levels were associated with longer S-LRP and S-EMG latencies, while high BIS levels had larger response accuracy. Extraverts, relative to introverts, along with those high relative to low on BAS-RR and BAS-I, exhibited smaller P3 amplitudes. The faster cortical premotor initiation, found in individuals high on extraversion, BAS-RI and low on FFFS, may account for their faster peripheral motor response initiation and execution. Smaller P3 amplitudes in extraverts and individuals high on BAS-RR and BAS-I may indicate reduced perceptual processing capacity in these individuals.

Intellectual Investment, Dopaminergic Gene Variation, and Life Events: A Critical Examination

Need for Cognition (NFC) and Openness to Ideas are intellectual investment traits that are characterized by a tendency to seek out, engage in and enjoy effortful cognitive activity. Little, however, is known about the extent to which they are influenced by genetic and environmental factors. With the present contribution, we aim at furthering our knowledge on the mechanisms underlying intellectual investment traits by following-up on a recent investigation of the role of dopaminergic gene variation in intellectual investment. Employing a standard approach that relied on null-hypothesis significance testing, we found that, first, two dopaminergic genetic variants interacted in modulating individual differences in NFC, but not in Openness to Ideas; that, second, negative life events played a role in the modulation of Openness to Ideas, but not of NFC; and that, third, negative life events as assessed using another measure were only marginally related to Openness to Ideas while positive life events were associated with both Openness to Ideas and NFC, with the latter effect being also dependent on DRD4 exon III genotype. However, employing a Bayesian approach, the assumption of a genetic effect on investment traits was overall not supported, while the assumption of a role of positive life events in the modulation of investment traits could be confirmed, with a tentative increment in the prediction of NFC by adding an interaction of positive life events and DRD4 variation to the main effect of positive life events. Our findings underscore the importance to use different approaches in the field of personality neuroscience. To gain deeper insight into the basis of personality traits does not only require to consider genetic as well as environmental influences and their interplay, but also requires more differentiated statistical analyses that can at least in part tackle the often inconsistent findings in this field.

Extraversion, neuroticism, and the electrocortical response to monetary rewards in adolescent girls

Affective personality traits, such as extraversion and neuroticism, are associated with individual differences in reward system functioning. The reward positivity (ΔRewP) is an event-related potential (ERP) component that indexes sensitivity to reward, and can be elicited by feedback indicating monetary gains relative to losses. In a sample of 508 adolescent girls, the current study examined the relationship between extraversion, neuroticism, and their respective facets and the ΔRewP. Results indicated an Extraversion × Neuroticism interaction, such that greater extraversion was associated with an increased ΔRewP, but only in the context of low neuroticism. This association was primarily due to the extraversion facet positive emotionality-high levels of positive emotionality were associated with an increased ΔRewP, but only in the context of low neuroticism. In addition, increased neuroticism diminished the age-related increase in the ΔRewP. The current study suggests that both extraversion and neuroticism are associated with reward system function in adolescence.

Risky economic choices and frontal EEG asymmetry in the context of Reinforcer-Sensitivity-Theory-5

This study investigated individual risky choice behavior in a gambling task and its relation with traits proposed by the Reinforcer-Sensitivity-Theory-5 (RST-5; Corr & McNaughton in Neuroscience and Biobehavioral Reviews, 36(10), 2339-2354, 2012) as well as with frontal EEG asymmetry. As assumed by the RST-5, the results showed independent influences of approach/avoidance and gain/loss sensitivities on participants' behavior in risky choices. Individual approach/avoidance sensitivity was predicted by trait measures of the behavioral approach system (BAS) and the behavioral inhibition system (BIS), while no such correlation was present for gain/loss sensitivity. EEG recordings revealed relatively stronger left-frontal cortical activity for trials with approach motivation compared to conflict and avoidance motivation. On the individual level, relatively stronger left-frontal cortical activity was associated with trait BAS. In addition, activity changes in frontal EEG asymmetry were associated relatively higher behavioral approach sensitivity. We conclude that frontal EEG asymmetry is an especially useful neuronal marker of BAS sensitivity and that the traits proposed by the RST-5 (measured by frontal EEG asymmetry and self-report) can be used to explain individual differences in risky choice behavior.

A pilot study of change in cerebral activity during personality rating by questionnaire and personal computer

The purpose of this study was to examine cerebral blood flow in the frontal cortex area during personality self-rating tasks. Our two hypotheses were (1) cerebral blood flow varies based on personality rating condition and (2) cerebral blood flow varies based on the personality traits. This experiment measured cerebral blood flow under 3 personal computer rating conditions and 2 questionnaire conditions. Comparing the rating conditions, the results of the t-test indicated that cerebral blood flow was higher in the questionnaire condition than it was in the personal computer condition. With respect to the Big Five, the result of the correlation coefficient, that is, cerebral blood flow during a personality rating task, changed according to the trait for agreeableness. The results of the analysis of the 5-cluster on individual differences indicated that certain personality traits were related to the factors that increased or decreased cerebral blood flow. An analysis of variance indicated that openness to experience and Behavioural Activation System-drive was significant given that participants with high intellectual curiosity were motivated in this experiment, thus, their cerebral blood flow may have increased. The significance of this experiment was that by employing certain performance measures we could examine differences in physical changes based on personality traits.

Preschool negative emotionality predicts activity and connectivity of the fusiform face area and amygdala in later childhood

Negative emotionality (NE) refers to individual differences in the propensity to experience and react with negative emotions and is associated with increased risk of psychological disorder. However, research on the neural bases of NE has focused almost exclusively on amygdala activity during emotional face processing. This study broadened this framework by examining the relationship between observed NE in early childhood and subsequent neural responses to emotional faces in both the amygdala and the fusiform face area (FFA) in a late childhood/early adolescent sample. Measures of NE were obtained from children at age 3 using laboratory observations, and functional magnetic resonance imaging (fMRI) data were collected when these children were between the ages of 9 and 12 while performing a visual stimulus identity matching task with houses and emotional faces as stimuli. Multiple regression analyses revealed that higher NE at age 3 is associated with significantly greater activation in the left amygdala and left FFA but lower functional connectivity between these two regions during the face conditions. These findings suggest that those with higher early NE have subsequent alterations in both activity and connectivity within an extended network during face processing.

Cognitive Appraisals Mediate Affective Reactivity in Affiliative Extraversion

Extraversion is comprised of two main components of affiliation and agency. Affiliative and agentic extraversion have been found to predict positive activation in response to appetitive stimuli, and affiliative extraversion also predicts warmth-affection in response to affiliative stimuli. The aim of this study was to test whether cognitive appraisals could account for these personality-emotion relationships. In an online experiment, 192 participants completed affiliative and appetitive imagery tasks, and reported their affect before and after each task. Participants also reported on how they appraised the imagined events. Affiliative extraversion was positively associated with warmth-affection following the affiliative imagery, and this relationship was mediated by appraisals of intrinsic pleasantness and compatibility with internal standards. Affiliative extraversion also predicted positive activation following the affiliative imagery, and this relationship was mediated by appraisals of importance. Neither agentic nor affiliative extraversion predicted any other form of affect following either the affiliative or appetitive imagery tasks. These results suggest that cognitive appraisals may be one mechanism that mediate affective reactivity in affiliative extraversion, although future confirmatory studies are required to further test this hypothesis.

Steroid 5α-reductase 2 deficiency leads to reduced dominance-related and impulse-control behaviors

The enzyme steroid 5α-reductase 2 (5αR2) catalyzes the conversion of testosterone into the potent androgen 5α-dihydrotestosterone. Previous investigations showed that 5αR2 is expressed in key brain areas for emotional and socio-affective reactivity, yet the role of this enzyme in behavioral regulation remains mostly unknown. Here, we profiled the behavioral characteristics of 5αR2 heterozygous (HZ) and knockout (KO) mice, as compared with their wild-type (WT) littermates. While male 5αR2 KO mice displayed no overt alterations in motoric, sensory, information-processing and anxiety-related behaviors, they exhibited deficits in neurobehavioral correlates of dominance (including aggression against intruders, mating, and tube dominance) as well as novelty-seeking and risk-taking responses. Furthermore, male 5αR2 KO mice exhibited reduced D₂-like dopamine receptor binding in the shell of the nucleus accumbens - a well-recognized molecular signature of social dominance. Collectively, these results suggest that 5αR2 is involved in the establishment of social dominance and its behavioral manifestations. Further studies are warranted to understand how the metabolic actions of 5αR2 on steroid profile may be implicated in social ranking, impulse control, and the modulation of dopamine receptor expression in the nucleus accumbens.

Affect and cortisol mechanisms through which acute exercise attenuates cigarette cravings during a temporary quit attempt

INTRODUCTION

A number of mechanisms have been proposed to explain how exercise attenuates cravings among temporarily abstinent smokers; however, research has presented mixed findings. The aim of this study was to further investigate the mechanistic role of positive and negative affect and cortisol in the exercise-craving reduction relationship.

METHODS

Adult smokers (N=110, male=56, M age=33.1, M cigarettes/day=15.4) provided baseline affective and cortisol data (T1). After an 18-h period of abstinence, participants were randomized to a passive sitting (PSG) or moderate exercise group (MEG; 40-68% of heart rate reserve) for 10min. Affect and cortisol data were also collected immediately before (T2) and after (T3) the condition.

RESULTS

The smoking abstinence manipulation increased cravings (p<0.001, eta=0.40) and negative affect (p<0.001, eta=0.17), as well as decreased positive affect (p<0.001, eta=0.08) and cortisol (trending, p=0.07, η2=0.04). As expected, a significant reduction in cravings from T2 to T3 was found for MEG but not PSG (p<0.001, eta=0.25). Mediation was tested using Sobel and bootstrapping tests with residual change scores of mediators and cravings. Findings showed that both positive and negative affect, but not cortisol, mediated the relationship between exercise and cravings.

CONCLUSIONS

Understanding the mechanisms by which exercise induces craving reductions will better allow researchers and healthcare professionals to infer causality and implement interventions guided by the processes that yield such desirable outcomes.

Opinion on monoaminergic contributions to traits and temperament

This article critically reviews evidence relating temperamental traits and personality factors to the monoamine neurotransmitters, especially dopamine and serotonin. The genetic evidence is not yet considered to be conclusive and it is argued that basic neuroscience research on the neural basis of behaviour in experimental animals should be taken more into account. While questionnaire and lexical methodology including the 'Five Factor' theory has been informative (mostly for the traits relevant to social functioning, i.e. personality), biologically oriented approaches should be employed with more objective, theoretically grounded measures of cognition and behaviour, combined with neuroimaging and psychopharmacology, where appropriate. This strategy will enable specific functions of monoamines and other neuromodulators such as acetylcholine and neuropeptides (such as orexin) to be defined with respect to their roles in modulating activity in specific neural networks-leading to a more realistic definition of their interactive roles in complex, biologically based traits (i.e. temperament).This article is part of the theme issue 'Diverse perspectives on diversity: multi-disciplinary approaches to taxonomies of individual differences'.

Associating resting-state connectivity with trait impulsivity

Psychometric research has identified stable traits that predict inter-individual differences in appetitive motivation and approach behavior. Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scales have been developed to quantitatively assess these traits. However, neural mechanisms corresponding to the proposed constructs reflected in BIS/BAS are still poorly defined. The ventral striatum (VS) and orbitofrontal cortex (OFC) are implicated in subserving reward-related functions that are also associated with the BAS. In this study, we examined whether functional connectivity between these regions predicts components of these scales. We employed resting-state functional connectivity and BIS/BAS scores assessed by a personality questionnaire. Participants completed a resting state run and the Behavioral Inhibition and Activation Systems (BIS/BAS) Questionnaire. Using resting-state BOLD, we assessed correlations between two basal ganglia ROIs (caudate and putamen) and bilateral OFC ROIs, establishing single subject connectivity summary scores. Summary scores were correlated with components of BIS/BAS scores. Results demonstrate a novel correlation between BAS-fun seeking and resting-state connectivity between middle OFC and putamen, implying that spontaneous synchrony between reward-processing regions may play a role in defining personality characteristics related to impulsivity.

Predicting personality from network-based resting-state functional connectivity

Personality is associated with variation in all kinds of mental faculties, including affective, social, executive, and memory functioning. The intrinsic dynamics of neural networks underlying these mental functions are reflected in their functional connectivity at rest (RSFC). We, therefore, aimed to probe whether connectivity in functional networks allows predicting individual scores of the five-factor personality model and potential gender differences thereof. We assessed nine meta-analytically derived functional networks, representing social, affective, executive, and mnemonic systems. RSFC of all networks was computed in a sample of 210 males and 210 well-matched females and in a replication sample of 155 males and 155 females. Personality scores were predicted using relevance vector machine in both samples. Cross-validation prediction accuracy was defined as the correlation between true and predicted scores. RSFC within networks representing social, affective, mnemonic, and executive systems significantly predicted self-reported levels of Extraversion, Neuroticism, Agreeableness, and Openness. RSFC patterns of most networks, however, predicted personality traits only either in males or in females. Personality traits can be predicted by patterns of RSFC in specific functional brain networks, providing new insights into the neurobiology of personality. However, as most associations were gender-specific, RSFC-personality relations should not be considered independently of gender.

Personality Influences the Relationship Between Primary Emotions and Religious/Spiritual Well-Being

The study of human emotions and personality provides valuable insights into the parameters of mental health and well-being. Affective neuroscience proposes that several levels of emotions - ranging from primary ones such as LUST or FEAR up to higher emotions such as spirituality - interact on a neural level. The present study aimed to further explore this theory. Furthermore, we hypothesized that personality - formed by bottom-up primary emotions and cortical top-down regulation - might act as a link between primary emotions and religious/spiritual well-being. A total sample of 167 (78% female) student participants completed the Affective Neuroscience Personality Scale (primary emotions), the Big Five Personality Inventory and the Multidimensional Inventory of Religious/Spiritual Well-Being (higher emotions). Correlation analyses confirmed the link between primary and higher emotions as well as their relation to personality. Further regression analyses indicated that personality dimensions mediate the relationship between primary and higher emotions. A substantial interaction between primary emotions, personality dimensions, and religious/spiritual well-being could be confirmed. From a developmental perspective, cortical top-down regulation might influence religious/spiritual well-being by forming relevant personality dimensions. Hence, CARE as well as Agreeableness seem of special importance. Future studies might focus on implications for clinical groups.