Truth, lies or self-deception? Striatal D(2/3) receptor availability predicts individual differences in social conformity

Using social rank as the lens to focus on the neural circuitry driving stress coping styles

Social hierarchy position in humans is negatively correlated with stress-related psychiatric disease risk. Animal models have largely corroborated human studies, showing that social rank can impact stress susceptibility and is considered to be a major risk factor in the development of psychiatric illness. Differences in stress coping style is one of several factors that mediate this relationship between social rank and stress susceptibility. Coping styles encompass correlated groupings of behaviors associated with differential physiological stress responses. Here, we discuss recent insights from animal models that highlight several neural circuits that can contribute to social rank-associated differences in coping style.

Resting-State Functional Connectivity of the Punishment Network Associated With Conformity

Fear of punishment prompts individuals to conform. However, why some people are more inclined than others to conform despite being unaware of any obvious punishment remains unclear, which means the dispositional determinants of individual differences in conformity propensity are poorly understood. Here, we explored whether such individual differences might be explained by individuals' stable neural markers to potential punishment. To do this, we first defined the punishment network (PN) by combining all potential brain regions involved in punishment processing. We subsequently used a voxel-based global brain connectivity (GBC) method based on resting-state functional connectivity (FC) to characterize the hubs in the PN, which reflected an ongoing readiness state (i.e., sensitivity) for potential punishment. Then, we used the within-network connectivity (WNC) of each voxel in the PN of 264 participants to explain their tendency to conform by using a conformity scale. We found that a stronger WNC in the right thalamus, left insula, postcentral gyrus, and dACC was associated with a stronger tendency to conform. Furthermore, the FC among the four hubs seemed to form a three-phase ascending pathway, contributing to conformity propensity at every phase. Thus, our results suggest that task-independent spontaneous connectivity in the PN could predispose individuals to conform.

Suggestibility is associated with alcohol self-administration, subjective alcohol effects, and self-reported drinking behavior

BACKGROUND

Suggestibility, defined as an individual's inclination to accept and internalize messages, has not been studied in relation to alcohol use. Peer conformity, a component of suggestibility, may be related to alcohol use, as peer groups show similarities in patterns of alcohol use. Few studies have assessed how suggestibility and peer conformity relate to alcohol self-administration or to reinforcing effects of alcohol.

AIMS

This study assessed whether suggestibility and peer conformity were associated with drinking behavior, alcohol self-administration, subjective response to alcohol, and drinking motives and expectancies.

METHODS

Study 1 participants were alcohol drinkers (n=20), who completed a laboratory study of free-access intravenous alcohol self-administration. Study 2 participants were adolescents and young adults, age 14-25 (n=150), with lifetime alcohol use. Participants completed surveys of suggestibility and drinking patterns (Study 1 and 2), subjective alcohol effects (Study 1 only), and alcohol motives and expectancies (Study 2 only).

RESULTS/OUTCOMES

In Study 1, participants with higher levels of suggestiblity self-administered more alcohol, and reported greater subjective alcohol effects. Peer conformity, though correlated with suggestibility, was not related to these measures. In Study 2, participants with higher suggestiblity reported more alcohol consumption, higher drinking motives and alcohol expectancies. Peer conformity was not related to alcohol consumption, but was related to coping and enhancement drinking motives, and all expectancies measures.

CONCLUSIONS/INTERPRETATION

Results indicate that suggestibility, beyond peer conformity, may be a critical factor to study when examining alcohol consumption behavior, and may provide insight into the development of alcohol use disorder.

Learning From Loss After Risk: Dissociating Reward Pursuit and Reward Valuation in a Naturalistic Foraging Task

A fundamental feature of addiction is continued use despite high-cost losses. One possible driver of this feature is a dissociation between reward pursuit and reward valuation. To test for this dissociation, we employed a foraging paradigm with real-time delays and video rewards. Subjects made stay/skip choices on risky and non-risky offers; risky losses were operationalized as receipt of the longer delay after accepting a risky deal. We found that reward likability following risky losses predicted reward pursuit (i.e., subsequent choices), while there was no effect on reward valuation or reward pursuit in the absence of such losses. Individuals with high trait externalizing, who may be vulnerable to addiction, showed a dissociation between these phenomena: they liked videos more after risky losses but showed no decrease in choosing to stay on subsequent risky offers. This suggests that the inability to learn from mistakes is a potential component of risk for addiction.

Resting-state Functional Connectivity and Deception: Exploring Individualized Deceptive Propensity by Machine Learning

Individuals show marked variability in determining to be honest or deceptive in daily life. A large number of studies have investigated the neural substrates of deception; however, the brain networks contributing to the individual differences in deception remain unclear. In this study, we sought to address this issue by employing a machine-learning approach to predict individuals' deceptive propensity based on the topological properties of whole-brain resting-state functional connectivity (RSFC). Participants finished the resting-state functional MRI (fMRI) data acquisition, and then, one week later, participated as proposers in a modified ultimatum game in which they spontaneously chose to be honest or deceptive. A linear relevance vector regression (RVR) model was trained and validated to examine the relationship between topological properties of networks of RSFC and actual deceptive behaviors. The machine-learning model sufficiently decoded individual differences in deception using three brain networks based on RSFC, including the executive controlling network (dorsolateral prefrontal cortex, middle frontal cortex, and orbitofrontal cortex), the social and mentalizing network (the temporal lobe, temporo-parietal junction, and inferior parietal lobule), and the reward network (putamen and thalamus). These networks have been found to form a signaling cognitive framework of deception by coding the mental states of others and the reward or values of deception or honesty, and integrating this information to make a final decision about being deceptive or honest. These findings suggest the potential of using RSFC as a task-independent neural trait for predicting deceptive propensity, and shed light on using machine-learning approaches in deception detection.

Brain neuroreceptor density and personality traits: towards dimensional biomarkers for psychiatric disorders

Positron emission tomography has, for 30 years, been used in numerous case-control studies searching for hypothesized differences in the density of neuroreceptor or transporter proteins in psychiatric disorders such as schizophrenia and depression. In most cases, the results have not been conclusive. One reason could be the sizeable interindividual variability in biochemical markers, which in twin studies have shown to emanate from both environmental and genetic factors, leading to low statistical power for the detection of group effects. On the other hand, the same interindividual variability has served as an opportunity for correlative studies on the biological underpinning of behaviour. Using this approach, a series of studies has linked markers for the dopamine and serotonin system to personality traits associated with psychiatric conditions. Based on increasing evidence for the view that many psychopathological states represent extremes of a continuum rather than distinct categories, this research strategy may lead to new biological insights about the vulnerability to and pathophysiology of major psychiatric disorders.This article is part of the theme issue 'Diverse perspectives on diversity: multi-disciplinary approaches to taxonomies of individual differences'.

Is dopamine D1 receptor availability related to social behavior? A positron emission tomography replication study

BACKGROUND

Associations between dopamine receptor levels and pro- and antisocial behavior have previously been demonstrated in human subjects using positron emission tomography (PET) and self-rated measures of personality traits. So far, only one study has focused on the dopamine D1-receptor (D1-R), finding a positive correlation with the trait social desirability, which is characterized by low dominant and high affiliative behavior, while physical aggression showed a negative correlation. The aim of the present study was to replicate these previous findings using a new independent sample of subjects.

MATERIALS AND METHODS

Twenty-six healthy males were examined with the radioligand [11C]SCH-23390, and completed the Swedish universities Scales of Personality (SSP) which includes measures of social desirability and physical trait aggression. The simplified reference tissue model with cerebellum as reference region was used to calculate BPND values in the whole striatum and limbic striatum. The two regions were selected since they showed strong association between D1-R availability and personality scores in the previous study. Pearson's correlation coefficients and replication Bayes factors were then employed to assess the replicability and robustness of previous results.

RESULTS

There were no significant correlations (all p values > 0.3) between regional BPND values and personality scale scores. Replication Bayes factors showed strong to moderate evidence in favor no relationship between D1-receptor availability and social desirability (striatum BF01 = 12.4; limbic striatum BF01 = 7.2) or physical aggression scale scores (limbic striatum BF01 = 3.3), compared to the original correlations.

DISCUSSION

We could not replicate the previous findings of associations between D1-R availability and either pro- or antisocial behavior as measured using the SSP. Rather, there was evidence in favor of failed replications of associations between BPND and scale scores. Potential reasons for these results are restrictive variance in both PET and personality outcomes due to high sample homogeneity, or that the previous findings were false positives.

Extrastriatal dopamine D2-receptor availability in social anxiety disorder

Alterations in the dopamine system are hypothesized to influence the expression of social anxiety disorder (SAD) symptoms. However, molecular imaging studies comparing dopamine function between patients and control subjects have yielded conflicting results. Importantly, while all previous investigations focused on the striatum, findings from activation and blood flow studies indicate that prefrontal and limbic brain regions have a central role in the pathophysiology. The objective of this study was to investigate extrastriatal dopamine D2-receptor (D2-R) availability in SAD. We examined 12 SAD patients and 16 healthy controls using positron emission tomography and the high-affinity D2-R radioligand [¹¹C]FLB457. Parametric images of D2-R binding potential were derived using the Logan graphical method with cerebellum as reference region. Two-tailed one-way independent ANCOVAs, with age as covariate, were used to examine differences in D2-R availability between groups using both region-based and voxel-wise analyses. The region-based analysis showed a medium effect size of higher D2-R levels in the orbitofrontal cortex (OFC) in patients, although this result did not remain significant after correction for multiple comparisons. The voxel-wise comparison revealed elevated D2-R availability in patients within OFC and right dorsolateral prefrontal cortex after correction for multiple comparisons. These preliminary results suggest that an aberrant extrastriatal dopamine system may be part of the disease mechanism in SAD.

It's all in the type of the task: Dopamine modulates kinematic patterns during competitive vs. cooperative interaction in Parkinson's disease

Increasing evidence suggests that a dysfunctional dopaminergic system affects the ability to socially interact. Since Parkinson's disease (PD) provides a model for assessing dopaminergic dysfunctions in humans, our study was designed to investigate social interactions in PD patients receiving dopamine replacement therapy (Levodopa=l-Dopa) and in neurologically healthy controls. We focused on the kinematics of one action, reaching to grasp a wooden block, which was performed within the context of two basic modes of social cognition, namely cooperation and competition. During the cooperative tasks, two participants were instructed to reach and grasp their respective objects and to cooperate in forming a specific configuration on the working table. During the competitive tasks, two participants were instructed to compete to place their own object at the bottom of a tower to be built on the working table. PD patients' ability to modulate motor patterning depending on the intention motivating the action they were about to perform was evaluated in both "on" (with l-Dopa) and "off" (without l-Dopa) states. Study results revealed that both the healthy controls and the 'on' PD patients had distinct kinematic patterns for cooperative and competitive actions and that these differed from patterns mirroring similar actions performed by those same participants in non social conditions. The kinematic patterns of the healthy controls and the 'on' patients were highly correlated during the cooperative tasks. The 'off' PD patients were, instead, unable to differentiate between isolated and social conditions. These results support the hypothesis that dopaminergic neurotransmission is involved in shaping the mechanisms underlying social interactions.

Exploring personality traits related to dopamine D2/3 receptor availability in striatal subregions of humans

While several studies have examined how particular personality traits are related to dopamine D2/3 receptor (D2/3R) availability in the striatum of humans, few studies have reported how multiple traits measured in the same persons are differentially related to D2/3R availability in different striatal sub-regions. We examined how personality traits measured with the Karolinska Scales of Personality are related to striatal D2/3R availability measured with [(11)C]-raclopride in 30 healthy humans. Based on previous the literature, five personality traits were hypothesized to be most likely related to D2/3R availability: impulsiveness, monotony avoidance, detachment, social desirability, and socialization. We found self-reported impulsiveness was negatively correlated with D2/3R availability in the ventral striatum and globus pallidus. After controlling for age and gender, monotony avoidance was also negatively correlated with D2/3R availability in the ventral striatum and globus pallidus. Socialization was positively correlated with D2/3R availability in the ventral striatum and putamen. After controlling for age and gender, the relationship between socialization and D2/3R availability in these regions survived correction for multiple comparisons (p-threshold=.003). Thus, within the same persons, different personality traits are differentially related to in vivo D2/3R availability in different striatal sub-regions.

Mesocorticolimbic dopamine functioning in primary psychopathy: A source of within-group heterogeneity

Despite similar emotional deficiencies, primary psychopathic individuals can be situated on a continuum that spans from controlled to disinhibited. The constructs on which primary psychopaths are found to diverge, such as self-control, cognitive flexibility, and executive functioning, are crucially regulated by dopamine (DA). As such, the goal of this review is to examine which specific alterations in the meso-cortico-limbic DA system and corresponding genes (e.g., TH, DAT, COMT, DRD2, DRD4) might bias development towards a more controlled or disinhibited expression of primary psychopathy. Based on empirical data, it is argued that primary psychopathy is generally related to a higher tonic and population activity of striatal DA neurons and lower levels of D2-type DA receptors in meso-cortico-limbic projections, which may boost motivational drive towards incentive-laden goals, dampen punishment sensitivity, and increase future reward-expectancy. However, increasingly higher levels of DA activity in the striatum (moderate versus pathological elevations), lower levels of DA functionality in the prefrontal cortex, and higher D1-to-D2-type receptor ratios in meso-cortico-limbic projections may lead to increasingly disinhibited and impetuous phenotypes of primary psychopathy. Finally, in order to provide a more coherent view on etiological mechanisms, we discuss interactions between DA and serotonin that are relevant for primary psychopathy.

Neural correlates of self-deception and impression-management

Self-deception and impression-management comprise two types of deceptive, but generally socially acceptable behaviours, which are common in everyday life as well as being present in a number of psychiatric disorders. We sought to establish and dissociate the 'normal' brain substrates of self-deception and impression-management. Twenty healthy participants underwent fMRI scanning at 3T whilst completing the 'Balanced Inventory of Desirable Responding' test under two conditions: 'fake good', giving the most desirable impression possible and 'fake bad' giving an undesirable impression. Impression-management scores were more malleable to manipulation via 'faking' than self-deception scores. Response times to self-deception questions and 'fake bad' instructions were significantly longer than to impression-management questions and 'fake good' instructions respectively. Self-deception and impression-management manipulation and 'faking bad' were associated with activation of medial prefrontal cortex (mPFC) and left ventrolateral prefrontal cortex (vlPFC). Impression-management manipulation was additionally associated with activation of left dorsolateral prefrontal cortex and left posterior middle temporal gyrus. 'Faking bad' was additionally associated with activation of right vlPFC, left temporo-parietal junction and right cerebellum. There were no supra-threshold activations associated with 'faking good'. Our neuroimaging data suggest that manipulating self-deception and impression-management and more specifically 'faking bad' engages a common network comprising mPFC and left vlPFC. Shorter response times and lack of dissociable neural activations suggests that 'faking good', particularly when it comes to impression-management, may be our most practiced 'default' mode.

An association of adult personality with prenatal and early postnatal growth: the EPQ lie-scale

Background

Recent studies have noted differences in social acquiescence and interpersonal relations among adults born preterm or with very low birth weight compared to full term adults. In addition, birth weight has been observed to be negatively correlated with lie-scale scores in two studies. We attempted to replicate and extend these studies by examining young adult lie-scale scores in a Danish birth cohort.

Method

Weight, length and head circumference of 9125 children from the Copenhagen Perinatal Cohort were measured at birth and at 1, 3 and 6 years. A subsample comprising 1182 individuals participated in a follow-up at 20–34 years and was administered the Eysenck Personality Questionnaire (EPQ) which includes a lie-scale (indicating social acquiescence or self-insight). Associations between lie-scale scores and weight, length and head circumference respectively were analysed by multiple linear regression adjusting for single-mother status, parity, mother’s age, father’s age, parental social status, age at EPQ measurement, intelligence, and adult size.

Results

Male infants with lower weight, length, and head-circumference at birth and the following three years grew up to have higher scores on the lie-scale as young adults. Most of these associations remained significant after adjustment for the included covariates. No associations were found for females. Analyses were also conducted with neuroticism, extraversion and psychoticism as outcome variables, but no significant associations were found for these traits after adjustment.

Conclusions

The findings replicate and extend findings from previous studies suggesting that size at birth and during the first three years of life is significantly associated with social acquiescence in adult men. They highlight the potential influence of prenatal and early postnatal development on personality growth and development.

Does human presynaptic striatal dopamine function predict social conformity?

Socially desirable responding (SDR) is a personality trait which reflects either a tendency to present oneself in an overly positive manner to others, consistent with social conformity (impression management (IM)), or the tendency to view one's own behaviour in an overly positive light (self-deceptive enhancement (SDE)). Neurochemical imaging studies report an inverse relationship between SDR and dorsal striatal dopamine D₂/₃ receptor availability. This may reflect an association between SDR and D₂/₃ receptor expression, synaptic dopamine levels or a combination of the two. In this study, we used a [¹⁸F]-DOPA positron emission tomography (PET) image database to investigate whether SDR is associated with presynaptic dopamine function. Striatal [¹⁸F]-DOPA uptake, (k(i)(cer), min⁻¹), was determined in two independent healthy participant cohorts (n=27 and 19), by Patlak analysis using a cerebellar reference region. SDR was assessed using the revised Eysenck Personality Questionnaire (EPQ-R) Lie scale, and IM and SDE were measured using the Paulhus Deception Scales. No significant associations were detected between Lie, SDE or IM scores and striatal [¹⁸F]-DOPA k(i)(cer). These results indicate that presynaptic striatal dopamine function is not associated with social conformity and suggests that social conformity may be associated with striatal D₂/₃ receptor expression rather than with synaptic dopamine levels.

Superiority illusion arises from resting-state brain networks modulated by dopamine

The majority of individuals evaluate themselves as superior to average. This is a cognitive bias known as the "superiority illusion." This illusion helps us to have hope for the future and is deep-rooted in the process of human evolution. In this study, we examined the default states of neural and molecular systems that generate this illusion, using resting-state functional MRI and PET. Resting-state functional connectivity between the frontal cortex and striatum regulated by inhibitory dopaminergic neurotransmission determines individual levels of the superiority illusion. Our findings help elucidate how this key aspect of the human mind is biologically determined, and identify potential molecular and neural targets for treatment for depressive realism.

Nature or nurture? Determining the heritability of human striatal dopamine function: an [18F]-DOPA PET study

Striatal dopamine function is important for normal personality, cognitive processes and behavior, and abnormalities are linked to a number of neuropsychiatric disorders. However, no studies have examined the relative influence of genetic inheritance and environmental factors in determining striatal dopamine function. Using [18F]-DOPA positron emission tomography (PET), we sought to determine the heritability of presynaptic striatal dopamine function by comparing variability in uptake values in same sex monozygotic (MZ) twins to dizygotic (DZ) twins. Nine MZ and 10 DZ twin pairs underwent high-resolution [18F]-DOPA PET to assess presynaptic striatal dopamine function. Uptake values for the overall striatum and functional striatal subdivisions were determined by a Patlak analysis using a cerebellar reference region. Heritability, shared environmental effects and non-shared individual-specific effects were estimated using a region of interest (ROI) analysis and a confirmatory parametric analysis. Overall striatal heritability estimates from the ROI and parametric analyses were 0.44 and 0.33, respectively. We found a distinction between striatal heritability in the functional subdivisions, with the greatest heritability estimates occurring in the sensorimotor striatum and the greatest effect of individual-specific environmental factors in the limbic striatum. Our results indicate that variation in overall presynaptic striatal dopamine function is determined by a combination of genetic factors and individual-specific environmental factors, with familial environmental effects having no effect. These findings underline the importance of individual-specific environmental factors for striatal dopaminergic function, particularly in the limbic striatum, with implications for understanding neuropsychiatric disorders such as schizophrenia and addictions.

Changes in dopamine D2-receptor binding are associated to symptom reduction after psychotherapy in social anxiety disorder

The dopamine system has been suggested to play a role in social anxiety disorder (SAD), partly based on molecular imaging studies showing reduced levels of striatal dopaminergic markers in patients compared with control subjects. However, the dopamine system has not been examined in frontal and limbic brain regions proposed to be central in the pathophysiology of SAD. In the present study, we hypothesized that extrastriatal dopamine D2-receptor (D2-R) levels measured using positron emission tomography (PET) would predict symptom reduction after cognitive behavior therapy (CBT). Nine SAD patients were examined using high-resolution PET and the high-affinity D2-R antagonist radioligand [(11)C]FLB 457, before and after 15 weeks of CBT. Symptom levels were assessed using the anxiety subscale of Liebowitz Social Anxiety Scale (LSAS(anx)). At posttreatment, there was a statistically significant reduction of social anxiety symptoms (P<0.005). Using a repeated measures analysis of covariance, significant effects for time and time × LSAS(anx) change on D2-R-binding potential (BP(ND)) were shown (P<0.05). In a subsequent region-by-region analysis, negative correlations between change in D2-R BP(ND) and LSAS(anx) change were found for medial prefrontal cortex and hippocampus (P<0.05). This is the first study to report a direct relationship between symptom change after psychological treatment and a marker of brain neurotransmission. Using an intra-individual comparison design, the study supports a role for the dopamine system in cortical and limbic brain regions in the pathophysiology of SAD.

Limbic striatal dopamine D2/3 receptor availability is associated with non-planning impulsivity in healthy adults after exclusion of potential dissimulators

Positron emission tomography (PET) studies have reported an association between reduced striatal dopamine D2/3 receptor availability and higher scores on self-report measures of trait impulsivity in healthy adults. However, impulsivity is a multi-faceted construct, and it is unclear which aspect(s) of impulsivity might be driving these associations. The current study aimed to investigate the relationship between limbic (ventral) striatal D2/3 receptor availability and individual components of impulsivity (attentional, motor and non-planning) using the Barratt Impulsiveness Scale (BIS-11) and [(11)C]raclopride PET in 23 healthy volunteers. A partial correlational analysis showed a significant association between non-planning impulsiveness (lack of forethought or 'futuring') and limbic D2/3 receptor availability, which was only apparent after the exclusion of potential dissimulators (indexed by high scores on impression management). Our findings suggest that non-planning impulsiveness is associated with individual variation in limbic striatal D2/3 receptor availability and that different facets of impulsivity may have specific neurochemical correlates. Future studies that combine D2/3 receptor imaging with behavioral measures of impulsivity are required to further elucidate the precise relationship between individual components of trait impulsivity and brain dopaminergic function.

Influence of prenatal iron deficiency and MAOA genotype on response to social challenge in rhesus monkey infants

Social and emotional behaviors are known to be sensitive to both developmental iron deficiency (ID) and monoamine oxidase A (MAOA) gene polymorphisms. In this study, male rhesus monkey infants deprived of dietary iron in utero were compared with iron sufficient (IS) controls (n = 10/group). Half of each group had low MAOA activity genotypes and half had high MAOA activity genotypes. A series of social response tests were conducted at 3-14 months of age. MAOA genotype influenced attention to a video of aggressive behavior, emotional expression (fear, grimace and sniff) in the social intruder test, social actions (displacement, grooming) in the social dyad test, and aggressive responses to a threatening picture. Interactions between MAOA and prenatal ID were seen in response to the aggressive video, in temperament ratings, in affiliative behavior in the social dyad test, in cortisol response in the social buffering test and in response to a social intruder and to pictures with social and nonsocial themes. In general, the effects of ID were dependent on MAOA genotype in terms of both direction and size of the effect. Nutrition/genotype interactions may shed new light on behavioral consequences of nutritional deprivation during brain development.

How the brain shapes deception: an integrated review of the literature

How do people tell a lie? One useful approach to addressing this question is to elucidate the neural substrates for deception. Recent conceptual and technical advances in functional neuroimaging have enabled exploration of the psychology of deception more precisely in terms of the specific neuroanatomical mechanisms involved. A growing body of evidence suggests that the prefrontal cortex plays a key role in deception, and some researchers have recently emphasized the importance of other brain regions, such as those responsible for emotion and reward. However, it is still unclear how these regions play a role in making effective decisions to tell a lie. To provide a framework for considering this issue, the present article reviews current accomplishments in the study of the neural basis of deception. First, evolutionary and developmental perspectives are provided to better understand how and when people can make use of deception. The ensuing section introduces several findings on pathological lying and its neural correlate. Next, recent findings in the cognitive neuroscience of deception based on functional neuroimaging and loss-of-function studies are summarized, and possible neural mechanisms underlying deception are proposed. Finally, the priority areas of future neuroscience research-human honesty and dishonesty-are discussed.