Aberrant social and cerebral responding in a competitive reaction time paradigm in criminal psychopaths

A quasi-experimental study in sibling dyads: differential provocation-aggression patterns in the interactive taylor aggression paradigm

Introduction

The Taylor Aggression Paradigm (TAP) is a well-established tool for assessing provocation-induced reactive aggression. We introduce an interactive version, the iTAP, with real-time opponents across 60 trials, including five simulated provocation trials in the middle. In this quasi-experimental study, we evaluate the effectiveness of the paradigm to investigate reactive aggression in interacting participants. The design allows us to employ the TAP in settings of high familiarity dyads, addressing an existing gap.

Method

Twenty-eight healthy same-sex adult sibling pairs (N = 56) competed against each other in the iTAP, exemplifying high familiarity through their social and emotional co-development, and mutual knowledge. Additionally, we explore naturally arising aggression types in terms of sibling pairs' reciprocal aggression trajectories across trials. Lastly, we investigate situational and personal variables influencing reactive aggression on the iTAP within high familiarity dyads.

Results

In line with non-interactive TAP versions, siblings employed a global "tit-for-tat" strategy in response to heightened provocation: Aggression increased during manipulated trials of increasing provocation, persisted during real interaction and declined in the final block, suggesting sibling co-regulation which was underscored by the convergence in within-pair aggression level. We found no gender differences in these dynamics but a trend for higher initial aggression levels within brother pairs and higher responsiveness to increased provocation in sister pairs. Overall aggression levels were related to situational variables including trial outcome (lost, won, and tie), Further, siblings' state anger correlated positively with aggression scores on the iTAP. Aggression was not reliably related to personal variables predicting aggression. We identified subgroups of sibling pairs with distinct provocation-aggression patterns related to differences in reported behavioral motivations and emotional states. The results highlight situational over personal variables in determining aggressive behavior on the task in this sample of healthy adults. While no direct link between sibling relationship quality and aggression was found, the overall behavior was likely influenced by the familiarity between siblings and the specific context of their relationship.

Conclusion

The iTAP demonstrates promise as a tool for studying reciprocal aggressive behavior. The emergence of different interaction patterns underscores the ecological validity introduced by the interactive context, which complements the standard versions of the TAP.

Neural correlates of episodic memory decline following electroconvulsive therapy: An exploratory functional magnetic resonance imaging study

BACKGROUND

Electroconvulsive therapy (ECT) is an efficient and rapid-acting treatment indicated for severe depressive disorders. While ECT is commonly accompanied by transient memory decline, the brain mechanisms underlying these side effects remain unclear.

AIMS

In this exploratory functional magnetic resonance (fMRI) study, we aimed to compare effects of ECT versus pharmacological treatment on neural response during episodic memory encoding in patients with affective disorders.

METHODS

This study included 32 ECT-treated patients (major depressive disorder (MDD), n = 23; bipolar depression, n = 9) and 40 partially remitted patients in pharmacological treatment (MDD, n = 24; bipolar disorder, n = 16). Participants underwent neuropsychological assessment, a strategic picture encoding fMRI scan paradigm, and mood rating. The ECT group was assessed before ECT (pre-ECT) and 3 days after their eighth ECT session (post-ECT).

RESULTS

Groups were comparable on age, gender, and educational years (ps ⩾ 0.05). Within-group analyses revealed a selective reduction in verbal learning and episodic memory pre- to post-ECT (p = 0.012) but no decline in global cognitive performance (p = 0.3). Functional magnetic resonance imaging analyses adjusted for mood symptoms revealed greater activity in ECT-treated patients than pharmacologically treated No-ECT patients across left precentral gyrus (PCG), right dorsomedial prefrontal cortex (dmPFC), and left middle frontal gyrus (MFG). In ECT-treated patients, greater decline in verbal learning and memory performance from pre- to post-ECT correlated with higher PCG response (r = -0.46, p = 0.008), but not with dmPFC or MFG activity (ps ⩾ 0.1), post-ECT.

CONCLUSIONS

Episodic memory decline was related to greater neural activity in the left PCG, but unrelated to increased dmPFC and MFG activity, immediately after ECT.

Neural basis of memory impairments and relation to functional disability in fully or partially remitted patients with affective disorders

Bipolar disorder (BD) and major depressive disorder (MDD) are associated with cognitive and functional impairment. Cognitive impairment is often associated with dorsal prefrontal cortex (dPFC) hypo-activity, but the neuronal correlates of functional disability is largely unknown. In this study, 91 patients with affective disorders in full or partial remission (BD, n = 67; MDD, n = 24) with objectively verified cognitive impairment and substantial functional disability underwent neuropsychological assessment and functional magnetic resonance imaging (fMRI) scan during which they completed a strategic picture-encoding task. For comparison, 36 matched healthy controls underwent an identical test protocol. Patients showed encoding-related hypo-activity in the dPFC compared to controls. In patients, lower right dlPFC activity was associated with poorer overall functioning and more antipsychotic drug use. In conclusion, memory impairments were underpinned by failure to recruit the dPFC during task performance which was associated with impaired functioning in fully or partially remitted patients with affective disorders. This aberrant neurocircuitry activity has implications for the design of future pro-cognitive interventions that aim to improve not only cognition but also real-world functioning.

Associations Between Psychopathic Traits and Laboratory-Based Aggression: Moderating Effects of Provocation and Distraction

There are two distinct combinations of psychopathic traits (primary and secondary) that have been proposed to be a function of unique cognitive-affective deficits. This study sought to use theories of psychopathy to understand the factors that exacerbate (i.e., provocation) and attenuate (i.e., distraction) aggression in individuals high in psychopathic traits in a controlled laboratory task. Male undergraduates, who scored across the range of primary and secondary psychopathic traits, completed the Taylor Aggression Paradigm (TAP; Taylor, 1967) under conditions of low and high provocation. Participants were also randomly assigned to either a distraction condition, in which they completed a distracting concurrent task, or a control condition, in which no such task was completed. Inconsistent with our prediction, results showed that regardless of condition, primary psychopathic traits were positively related to laboratory aggression. Consistent with our hypothesis, a positive association between secondary psychopathic traits and laboratory physical aggression was observed following high provocation among nondistracted participants; this association was significantly reduced among distracted participants. These results clarify the factors that contribute to aggression for individuals high in psychopathic traits and may provide directions for future intervention development.

Action-based cognitive remediation in bipolar disorder improved verbal memory but had no effect on the neural response during episodic memory encoding

Verbal memory and executive function impairments are common in remitted patients with bipolar disorder (BD). We recently found that Action-Based Cognitive Remediation (ABCR) may improve executive function and verbal memory in BD. Here, we investigated neuronal changes associated with ABCR treatment-related memory improvement in a longitudinal functional MRI (fMRI) study. Forty-five patients with remitted BD (ABCR: n = 26, control treatment: n = 19) completed a picture-encoding task during fMRI and tests of verbal memory and executive function outside the scanner before and after two weeks of ABCR/control treatment. The cognitive assessment was performed again following ten weeks of treatment. Thirty-four healthy controls underwent the same test protocol once for baseline comparisons. Patients showed a moderate improvement in a domain composite of verbal learning and memory both after two weeks and ten weeks of ABCR treatment, which correlated with improved executive function. At baseline, patients showed encoding-related hypoactivity in dorsal prefrontal cortex compared to healthy controls. However, treatment was not associated with significant task-related neuronal activity changes. Improved verbal learning and memory may have occurred through strengthened strategic processing targeted by ABCR. However, picture-encoding paradigms may be suboptimal to capture the neural correlates of this improvement, possibly by failing to engage strategic encoding processes.

Change in prefrontal activity and executive functions after action-based cognitive remediation in bipolar disorder: a randomized controlled trial

Cognitive impairment is prevalent in bipolar disorder (BD) but treatments with pro-cognitive effects are lacking. Insight concerning the neurocircuitry of cognitive improvement could provide a biomarker for pro-cognitive effects to advance treatment development. The dorsal prefrontal cortex (dPFC) is a promising region for such treatment target engagement. The aim of this functional magnetic resonance imaging (fMRI) study was to examine the effects of action-based cognitive remediation (ABCR) on early change in the dPFC blood-oxygen-level-dependent response in patients with BD in remission, and whether the observed neural change predicted improved executive functions following 10 weeks of treatment. Forty-five participants with remitted BD (ABCR: n = 26, control treatment: n = 19) completed a spatial n-back working memory task during fMRI and executive function tasks outside the scanner before and after two weeks of ABCR/control treatment, and an additional assessment of executive function at treatment completion. Thirty-four healthy controls underwent a single fMRI and executive function assessment for baseline comparisons. We found an early reversal of pretreatment hypo-activity in the dorsolateral prefrontal cortex (dlPFC) following ABCR vs. control during both high-load (2-back > 1-back) working memory (WM) (F(1,43) = 5.69, p = 0.02, η2 = 0.12) and general WM (2-back > 0-back) (F(1,43) = 5.61, p = 0.02, η2 = 0.12). This dlPFC activity increase predicted improved executive functions at treatment completion (high-load WM: B = -0.45, p = 0.01, general WM: B = -0.41, p < 0.01), independent of changes in subsyndromal symptoms. In conclusion, early dPFC increase may provide a neurocircuitry-based biomarker for pro-cognitive effects. Future cognition trials should include fMRI assessments to confirm the validity of this putative biomarker model across disorders with cognitive impairment.

The neurobiology of human aggressive behavior: Neuroimaging, genetic, and neurochemical aspects

In modern societies, there is a strive to improve the quality of life related to risk of crimes which inevitably requires a better understanding of brain determinants and mediators of aggression. Neurobiology provides powerful tools to achieve this end. Pre-clinical and clinical studies show that changes in regional volumes, metabolism-function and connectivity within specific neural networks are related to aggression. Subregions of prefrontal cortex, insula, amygdala, basal ganglia and hippocampus play a major role within these circuits and have been consistently implicated in biology of aggression. Genetic variations in proteins regulating the synthesis, degradation, and transport of serotonin and dopamine as well as their signal transduction have been found to mediate behavioral variability observed in aggression. Gene-gene and gene-environment interactions represent additional important risk factors for aggressiveness. Considering the social burden of pathological forms of aggression, more basic and translational studies should be conducted to accelerate applications to clinical practice, justice courts, and policy making.

Effect of Modulating DLPFC Activity on Antisocial and Prosocial Behavior: Evidence From a tDCS Study

Antisocial behavior and prosocial behavior in the condition of inequality have long been observed in daily life. Understanding the neurological mechanisms and brain regions associated with antisocial and prosocial behavior and the development of new interventions are important for reducing violence and inequality. Fortunately, neurocognitive research and brain imaging research have found a correlation between antisocial or prosocial behavior and the prefrontal cortex. Recent brain stimulation research adopting transcranial direct current stimulation or transcranial magnetic stimulation has shown a causal relationship between brain regions and behaviors, but the findings are mixed. In the present study, we aimed to study whether stimulation of the DLPFC can change participants’ antisocial and prosocial behavior in the condition of inequality. We integrated antisocial and prosocial behavior in a unified paradigm. Based on this paradigm, we discussed costly and cost-free antisocial and prosocial behavior. In addition, we also measured participants’ disadvantageous and advantageous inequality aversion. The current study revealed an asymmetric effect of bilateral stimulation over the DLPFC on costly antisocial behavior, while such an effect of antisocial behavior without cost and prosocial behavior with and without cost were not observed. Moreover, costly antisocial behavior exhibited by men increased after receiving right anodal/left cathodal stimulation and decreased after receiving right cathodal anodal/left anodal stimulation compared with the behavior observed under sham stimulation. However, subjects’ inequality aversion was not influenced by tDCS.

Gray matter asymmetry in the orbitofrontal cortex in relation to psychopathic traits in adolescents

BACKGROUND

Structural abnormalities in the orbitofrontal cortex (OFC) of incarcerated psychopaths have been well documented. However, the neural correlates of psychopathic traits in younger and nonclinical samples remain poorly understood.

AIM

The present study aimed to examine the structural brain asymmetry in the OFC in relation to dimensions of psychopathic traits in adolescents from the community.

METHOD

In 29 youths from the community, childhood psychopathic traits including narcissism, impulsivity, and callous-unemotional traits were assessed when they were 7- to 10 years old (Time 1), and their gray matter (GM) volumes were measured using structural Magnetic Resonance Imaging when they were 10- to 14 years old (Time 2).

RESULTS

After controlling for age, sex, IQ, pubertal stage, and whole-brain volumes, callous-unemotional traits were associated with right-left asymmetry in the medial OFC (mOFC), that is, smaller right mOFC GM as compared to the left. Impulsivity was associated with left-right asymmetry in the mOFC, that is, smaller left mOFC than the right. Narcissism was not associated with any GM asymmetry measure. No significant association was found for the lateral OFC, amygdala, caudate and putamen.

CONCLUSION

The present findings provide further support that dimensions of psychopathic traits may have distinct neurobiological correlates.

The emerging neuroscience of social punishment: Meta-analytic evidence

Social punishment (SOP)-third-party punishment (TPP) and second-party punishment (SPP)-sanctions norm-deviant behavior. The hierarchical punishment model (HPM) posits that TPP is an extension of SPP and both recruit common processes engaging large-scale domain-general brain networks. Here, we provided meta-analytic evidence to the HPM by combining the activation likelihood estimation approach with connectivity analyses and hierarchical clustering analyses. Although both forms of SOP engaged the dorsolateral prefrontal cortex and bilateral anterior insula (AI), a functional differentiation also emerged with TPP preferentially engaging social cognitive regions (temporoparietal junction) and SPP affective regions (AI). Further, although both TPP and SPP recruit domain-general networks (salience, default-mode, and central-executive networks), some specificity in network organization was observed. By revealing differences and commonalities of the neural networks consistently activated by different types of SOP, our findings contribute to a better understanding of the neuropsychological mechanisms of social punishment behavior--one of the most peculiar human behaviors.

High levels of psychopathic traits increase the risk of transferring reactive aggression to innocent people after provocation: Evidence from an ERP study

This study investigated the neuropsychological underpinnings of reactive aggression toward innocent people in a student population with different levels of psychopathic traits. While recording event-related potentials, participants (divided into high/low psychopathic [HP/LP] traits groups) competed against two fictitious opponents in a modified Taylor Aggression Paradigm. We found that the HP group compared to the LP group selected more often high-intensity punishment for the second innocent opponent after being provoked by the first opponent. Further, a more negative N2 and a smaller P3 was found in the HP group while punishing the innocents-reflecting a tendency on antisocial-aggressive behavior. Finally, both groups showed a more negative FRN for losing than winning trials when seeing the outcome of the game. Our results suggest that high psychopathic traits increase the risk of transferring provoked aggression to innocent people-offering a psychophysiological perspective for explaining and predicting aggression against the innocents in social interactions.

Manipulating the Perceived Shape and Color of a Virtual Limb Can Modulate Pain Responses

Changes in body representation may affect pain perception. The effect of a distorted body image, such as the telescoping effect in amputee patients, on pain perception, is unclear. This study aimed to investigate whether distorting an embodied virtual arm in virtual reality (simulating the telescoping effect in amputees) modulated pain perception and anticipatory responses to pain in healthy participants. Twenty-seven right-handed participants were immersed in virtual reality and the virtual arm was shown with three different levels of distortion with a virtual threatening stimulus either approaching or contacting the virtual hand. We evaluated pain/discomfort ratings, ownership, and skin conductance responses (SCRs) after each condition. Viewing a distorted virtual arm enhances the SCR to a threatening event with respect to viewing a normal control arm, but when viewing a reddened-distorted virtual arm, SCR was comparatively reduced in response to the threat. There was a positive relationship between the level of ownership over the distorted and reddened-distorted virtual arms with the level of pain/discomfort, but not in the normal control arm. Contact with the threatening stimulus significantly enhances SCR and pain/discomfort, while reduced SCR and pain/discomfort were seen in the simulated-contact condition. These results provide further evidence of a bi-directional link between body image and pain perception.

Exogenous testosterone and the monoamine-oxidase A polymorphism influence anger, aggression and neural responses to provocation in males

Testosterone and the monoamine oxidase-A (MAOA) polymorphism are potential neuromodulators for aggression. By acting on similar brain circuits, they might interactively influence human behavior. The current study investigates the causal role of testosterone on aggression-related brain activity and the potential interaction with the MAOA polymorphism. In a double-blind process, 93 healthy males received a testosterone or placebo gel. In an fMRI session, participants performed a Taylor aggression paradigm in which they received provoking feedback and could afterwards decide how aggressively they would react. Testosterone and cortisol levels as well as subjective anger were assessed prior and after the task. Circulating testosterone levels were higher in carriers of the long compared to the short MAOA allele. An interaction of the MAOA polymorphism and testosterone administration was identified in the cuneus, where short allele carriers in the placebo group showed diminished activity in the decision period. Task-related anger was significantly higher in this group. Overall, a mesocorticolimbic network was implicated in processing of high versus low provoking feedback, and core hubs of the default mode network were implicated in the subsequent decision after high versus low provocation. Testosterone administration increased activation in this network. The data provides evidence for an interaction of the MAOA polymorphism and exogenous testosterone on anger and suggests that interactive effects on the brain signal could underlie differential emotional reactivity. The increased default mode activation in the testosterone group suggests an enhanced engagement of social cognition related regions possibly supporting responsivity towards social provocation. This article is part of the Special Issue entitled 'Current status of the neurobiology of aggression and impulsivity'.

The contribution of brain imaging to the understanding of psychopathy

Psychopathy is a personality type characterized by both callous emotional dysfunction and deviant behavior that affects society in the form of actions that harm others. Historically, researchers have been concerned with seeking data and arguments to support a neurobiological foundation of psychopathy. In the past few years, increasing research has begun to reveal brain alterations putatively underlying the enigmatic psychopathic personality. In this review, we describe the brain anatomical and functional features that characterize psychopathy from a synthesis of available neuroimaging research and discuss how such brain anomalies may account for psychopathic behavior. The results are consistent in showing anatomical alterations involving primarily a ventral system connecting the anterior temporal lobe to anterior and ventral frontal areas, and a dorsal system connecting the medial frontal lobe to the posterior cingulate cortex/precuneus complex and, in turn, to medial structures of the temporal lobe. Functional imaging data indicate that relevant emotional flow breakdown may occur in both these brain systems and suggest specific mechanisms via which emotion is anomalously integrated into cognition in psychopathic individuals during moral challenge. Directions for future research are delineated emphasizing, for instance, the relevance of further establishing the contribution of early life stress to a learned blockage of emotional self-exposure, and the potential role of androgenic hormones in the development of cortical anomalies.

Towards a biomarker model for cognitive improvement: No change in memory-related prefrontal engagement following a negative cognitive remediation trial in bipolar disorder

BACKGROUND

Cognitive deficits are prevalent in bipolar disorder during remission but effective cognition treatments are lacking due to insufficient insight into the neurobiological targets of cognitive improvement. Emerging data suggest that dorsal prefrontal cortex target engagement is a key neurocircuitry biomarker of pro-cognitive treatment effects.

AIMS

In this randomized controlled functional magnetic resonance imaging study, we test this hypothesis by investigating the effects of an ineffective cognitive remediation intervention on dorsal prefrontal response during strategic memory encoding and working memory engagement.

METHODS

Bipolar disorder patients in partial remission with subjective cognitive difficulties were randomized to receive 12-week group-based cognitive remediation ( n = 13) or to continue their standard treatment ( n = 14). The patients performed a strategic episodic picture encoding task and a spatial n-back working memory task under functional magnetic resonance imaging at baseline and following cognitive remediation or standard treatment.

RESULTS

The right dorsolateral prefrontal cortex was commonly activated by both strategic memory tasks across all patients. The task-related prefrontal engagement was not altered by cognitive remediation relative to standard treatment. The dorsolateral prefrontal cortex response was not significantly associated with recall accuracy or working memory performance.

CONCLUSIONS

As hypothesized, no task-related change in prefrontal activity was observed in a negative cognitive remediation trial in remitted bipolar disorder patients. By complementing previous findings linking cognitive improvement with increased dorsolateral prefrontal cortex engagement, our negative findings provide additional validity evidence to the dorsal prefrontal target engagement biomarker model of cognitive improvement by strengthening the proposed causality between modulation of dorsolateral prefrontal cortex engagement and pro-cognitive effects.

Alterations in anterior cingulate cortex myoinositol and aggression in veterans with suicidal behavior: A proton magnetic resonance spectroscopy study

Studies investigating the neurochemical changes that correspond with suicidal behavior (SB) have not yielded conclusive results. Suicide correlates such as aggression have been used to explore risk factors for SB. Yet the neurobiological basis for the association between aggression and SB is unclear. Aggression and SB are both prevalent in veterans relative to civilian populations. The current study evaluated the relationship between brain chemistry in the anterior (ACC) and the posterior cingulate cortex (POC), as well as the relationship between aggression and SB in a veteran population using proton magnetic resonance spectroscopy (¹H-MRS). Single-voxel MRS data at 3 Tesla (T) were acquired from the ACC and POC voxels using a 2-dimensional J-resolved point spectroscopy sequence and quantified using the ProFit algorithm. Participants also completed a structured diagnostic interview and a clinical battery. Our results showed that the myoinositol (mI)/H2O ratio in the ACC and POC was significantly higher in veterans who reported SB when compared to veterans who did not. The two groups did not differ significantly with regard to other metabolites. Second, verbal aggression and SB measures positively correlated with mI/H2O in the ACC. Finally, verbal aggression mediated the relationship between mI/H2O in the ACC and SB.

Task Division within the Prefrontal Cortex: Distinct Neuron Populations Selectively Control Different Aspects of Aggressive Behavior via the Hypothalamus

An important question in behavioral neurobiology is how particular neuron populations and pathways mediate the overall roles of brain structures. Here we investigated this issue by studying the medial prefrontal cortex (mPFC), an established locus of inhibitory control of aggression. We established in male rats that dominantly distinct mPFC neuron populations project to and produce dense fiber networks with glutamate release sites in the mediobasal hypothalamus (MBH) and lateral hypothalamus (LH; i.e., two executory centers of species-specific and violent bites, respectively). Optogenetic stimulation of mPFC terminals in MBH distinctively increased bite counts in resident/intruder conflicts, whereas the stimulation of similar terminals in LH specifically resulted in violent bites. No other behaviors were affected by stimulations. These findings show that the mPFC controls aggressiveness by behaviorally dedicated neuron populations and pathways, the roles of which may be opposite to those observed in experiments where the role of the whole mPFC (or of its major parts) has been investigated. Overall, our findings suggest that the mPFC organizes into working units that fulfill specific aspects of its wide-ranging roles.SIGNIFICANCE STATEMENT Aggression control is associated with many cognitive and emotional aspects processed by the prefrontal cortex (PFC). However, how the prefrontal cortex influences quantitative and qualitative aspects of aggressive behavior remains unclear. We demonstrated that dominantly distinct PFC neuron populations project to the mediobasal hypothalamus (MBH) and the lateral hypothalamus (LH; i.e., two executory centers of species-specific and violent bites, respectively). Stimulation of mPFC fibers in MBH distinctively increased bite counts during fighting, whereas stimulation of similar terminals in LH specifically resulted in violent bites. Overall, our results suggest a direct prefrontal control over the hypothalamus, which is involved in the modulation of quantitative and qualitative aspects of aggressive behavior through distinct prefrontohypothalamic projections.

A Conceptual Review of Lab-Based Aggression Paradigms

Aggression is often defined as a behavior that is done with the intent to harm an individual who is believed to want avoid being harmed (e.g., Baron & Richardson, 1994). Accordingly, social scientists have developed several tasks to study aggression in laboratory settings; tasks that we refer to as “lab-based aggression paradigms.” However, because of the legal, ethical, and practical issues inherent in provoking aggression within the confines of a laboratory setting, it is feasible to study only very mildly harmful aggression. The current conceptual review examines the criteria that are necessary to study aggression in a laboratory setting, discusses the strengths and weaknesses of several new and/or commonly-used lab-based aggression paradigms, and offers recommendations for the future of lab-based aggression research. Collectively, we hope the current discussion helps researchers to describe the contributions and limitations of lab-based aggression research and, ultimately, helps to improve the informativeness of lab-based aggression research.

Functional Neuroimaging in Psychopathy

BACKGROUND AND AIM

Psychopathy is associated with cognitive and affective deficits causing disruptive, harmful and selfish behaviour. These have considerable societal costs due to recurrent crime and property damage. A better understanding of the neurobiological bases of psychopathy could improve therapeutic interventions, reducing the related social costs. To analyse the major functional neural correlates of psychopathy, we reviewed functional neuroimaging studies conducted on persons with this condition.

METHODS

We searched the PubMed database for papers dealing with functional neuroimaging and psychopathy, with a specific focus on how neural functional changes may correlate with task performances and human behaviour.

RESULTS

Psychopathy-related behavioural disorders consistently correlated with dysfunctions in brain areas of the orbitofrontal-limbic (emotional processing and somatic reaction to emotions; behavioural planning and responsibility taking), anterior cingulate-orbitofrontal (correct assignment of emotional valence to social stimuli; violent/aggressive behaviour and challenging attitude) and prefrontal-temporal-limbic (emotional stimuli processing/response) networks. Dysfunctional areas more consistently included the inferior frontal, orbitofrontal, dorsolateral prefrontal, ventromedial prefrontal, temporal (mainly the superior temporal sulcus) and cingulated cortices, the insula, amygdala, ventral striatum and other basal ganglia.

CONCLUSIONS

Emotional processing and learning, and several social and affective decision-making functions are impaired in psychopathy, which correlates with specific changes in neural functions.

The Neurobiology of Impulsive Aggression

This selective review provides a model of the neurobiology of impulsive aggression from a cognitive neuroscience perspective. It is argued that prototypical cases of impulsive aggression, those associated with anger, involve the recruitment of the acute threat response system structures; that is, the amygdala, hypothalamus, and periaqueductal gray. It is argued that whether the recruitment of these structures results in impulsive aggression or not reflects the functional roles of ventromedial frontal cortex and dorsomedial frontal and anterior insula cortex in response selection. It is also argued that impulsive aggression may occur because of impaired decision making. The aggression may not be accompanied by anger, but it will reflect disrupted evaluation of the rewards/benefits of the action.

Stress and the social brain: behavioural effects and neurobiological mechanisms

Stress often affects our social lives. When undergoing high-level or persistent stress, individuals frequently retract from social interactions and become irritable and hostile. Predisposition to antisocial behaviours - including social detachment and violence - is also modulated by early life adversity; however, the effects of early life stress depend on the timing of exposure and genetic factors. Research in animals and humans has revealed some of the structural, functional and molecular changes in the brain that underlie the effects of stress on social behaviour. Findings in this emerging field will have implications both for the clinic and for society.

Frontal and striatal alterations associated with psychopathic traits in adolescents

Neuroimaging research has demonstrated a range of structural deficits in adults with psychopathy, but little is known about structural correlates of psychopathic tendencies in adolescents. Here we examined structural magnetic resonance imaging (sMRI) data obtained from 14-year-old adolescents (n=108) using tensor-based morphometry (TBM) to isolate global and localized differences in brain tissue volumes associated with psychopathic traits in this otherwise healthy developmental population. We found that greater levels of psychopathic traits were correlated with increased brain tissue volumes in the left putamen, left ansa peduncularis, right superiomedial prefrontal cortex, left inferior frontal cortex, right orbitofrontal cortex, and right medial temporal regions and reduced brain tissues volumes in the right middle frontal cortex, left superior parietal lobule, and left inferior parietal lobule. Post hoc analyses of parcellated regional volumes also showed putamen enlargements to correlate with increased psychopathic traits. Consistent with earlier studies, findings suggest poor decision-making and emotional dysregulation associated with psychopathy may be due, in part, to structural anomalies in frontal and temporal regions whereas striatal structural variations may contribute to sensation-seeking and reward-driven behavior in psychopathic individuals. Future studies will help clarify how disturbances in brain maturational processes might lead to the developmental trajectory from psychopathic tendencies in adolescents to adult psychopathy.

Reducing proactive aggression through non-invasive brain stimulation

Aggressive behavior poses a threat to human collaboration and social safety. It is of utmost importance to identify the functional mechanisms underlying aggression and to develop potential interventions capable of reducing dysfunctional aggressive behavior already at a brain level. We here experimentally shifted fronto-cortical asymmetry to manipulate the underlying motivational emotional states in both male and female participants while assessing the behavioral effects on proactive and reactive aggression. Thirty-two healthy volunteers received either anodal transcranial direct current stimulation to increase neural activity within right dorsolateral prefrontal cortex, or sham stimulation. Aggressive behavior was measured with the Taylor Aggression Paradigm. We revealed a general gender effect, showing that men displayed more behavioral aggression than women. After the induction of right fronto-hemispheric dominance, proactive aggression was reduced in men. This study demonstrates that non-invasive brain stimulation can reduce aggression in men. This is a relevant and promising step to better understand how cortical brain states connect to impulsive actions and to examine the causal role of the prefrontal cortex in aggression. Ultimately, such findings could help to examine whether the brain can be a direct target for potential supportive interventions in clinical settings dealing with overly aggressive patients and/or violent offenders.

Effects of adverse early-life events on aggression and anti-social behaviours in animals and humans

We review the impact of early adversities on the development of violence and antisocial behaviour in humans, and present three aetiological animal models of escalated rodent aggression, each disentangling the consequences of one particular adverse early-life factor. A review of the human data, as well as those obtained with the animal models of repeated maternal separation, post-weaning social isolation and peripubertal stress, clearly shows that adverse developmental conditions strongly affect aggressive behaviour displayed in adulthood, the emotional responses to social challenges and the neuronal mechanisms activated by conflict. Although similarities between models are evident, important differences were also noted, demonstrating that the behavioural, emotional and neuronal consequences of early adversities are to a large extent dependent on aetiological factors. These findings support recent theories on human aggression, which suggest that particular developmental trajectories lead to specific forms of aggressive behaviour and brain dysfunctions. However, dissecting the roles of particular aetiological factors in humans is difficult because these occur in various combinations; in addition, the neuroscientific tools employed in humans still lack the depth of analysis of those used in animal research. We suggest that the analytical approach of the rodent models presented here may be successfully used to complement human findings and to develop integrative models of the complex relationship between early adversity, brain development and aggressive behaviour.

Social neuroscience and its potential contribution to psychiatry

Most mental disorders involve disruptions of normal social behavior. Social neuroscience is an interdisciplinary field devoted to understanding the biological systems underlying social processes and behavior, and the influence of the social environment on biological processes, health and well-being. Research in this field has grown dramatically in recent years. Active areas of research include brain imaging studies in normal children and adults, animal models of social behavior, studies of stroke patients, imaging studies of psychiatric patients, and research on social determinants of peripheral neural, neuroendocrine and immunological processes. Although research in these areas is proceeding along largely independent trajectories, there is increasing evidence for connections across these trajectories. We focus here on the progress and potential of social neuroscience in psychiatry, including illustrative evidence for a rapid growth of neuroimaging and genetic studies of mental disorders. We also argue that neuroimaging and genetic research focused on specific component processes underlying social living is needed.

Out of control: evidence for anterior insula involvement in motor impulsivity and reactive aggression

Inhibiting impulsive reactions while still defending one's vital resources is paramount to functional self-control and successful development in a social environment. However, this ability of successfully inhibiting, and thus controlling one's impulsivity, often fails, leading to consequences ranging from motor impulsivity to aggressive reactions following provocation. Although inhibitory failure represents the underlying mechanism, the neurocognition of social aggression and motor response inhibition have traditionally been investigated in separation. Here, we aimed to directly investigate and compare the neural mechanisms underlying the failure of inhibition across those different modalities of self-control. We used functional imaging to reveal the overlap in neural correlates between failed motor response inhibition (measured by a go/no-go task) and reactive aggression (measured by the Taylor aggression paradigm) in healthy males. The core overlap of neural correlates was located in the anterior insula, suggesting common anterior insula involvement in motor impulsivity as well as reactive aggression. This evidence regarding an overarching role of the anterior insula across different modalities of self-control enables an integrative perspective on insula function and a better integration of cognitive, social and emotional factors into a comprehensive model of impulsivity. Furthermore, it can eventually lead to a better understanding of clinical syndromes involving inhibitory deficits.

Physiological correlates of psychopathy, antisocial personality disorder, habitual aggression, and violence

This chapter reviews the existing literature on physiological correlates of psychopathy, antisocial personality disorder, and persistent violence/aggression. Coverage is provided of findings from studies utilizing peripheral, electrocortical, and neuroimaging measures. The review begins with a discussion of how psychopathy and antisocial personality are defined, and how these conditions relate to one another and to violent behavior. A case is made that the relationships psychopathy and ASPD show with violent and aggressive behavior, and similarities and differences in associations of each with physiological measures of various types can be understood in terms of symptomatic features these conditions have in common versus features that distinguish them. Following this, an overview is provided of major lines of evidence emerging from psychophysiological and neuroimaging studies conducted to date on these conditions. The final section of the chapter summarizes what has been learned from these existing studies and discusses implications and directions for future research.

White matter deficits in psychopathic offenders and correlation with factor structure

Psychopathic offenders show a persistent pattern of emotional unresponsivity to the often horrendous crimes they perpetrate. Recent studies have related psychopathy to alterations in white matter. Therefore, diffusion tensor imaging followed by tract-based spatial statistics (TBSS) analysis in 11 psychopathic offenders matched to 11 healthy controls was completed. Fractional anisotropy was calculated within each voxel and comparisons were made between groups using a permutation test. Any clusters of white matter voxels different between groups were submitted to probabilistic tractography. Significant differences in fractional anisotropy were found between psychopathic offenders and healthy controls in three main white matter clusters. These three clusters represented two major networks: an amygdalo-prefrontal network, and a striato-thalamo-frontal network. The interpersonal/affective component of the PCL-R correlated with white matter deficits in the orbitofrontal cortex and frontal pole whereas the antisocial component correlated with deficits in the striato-thalamo-frontal network. In addition to replicating earlier work concerning disruption of an amygdala-prefrontal network, we show for the first time that white matter integrity in a striato-thalamo-frontal network is disrupted in psychopathic offenders. The novelty of our findings lies in the two dissociable white matter networks that map directly onto the two major factors of psychopathy.

Punishing unfairness: rewarding or the organization of a reactively aggressive response?

OBJECTIVES

The neural correlates of human cooperative behavior remain poorly understood. Previous work has suggested that increases in striatal activation while punishing unfair offers represents reward signaling. However, other regions are also implicated when punishing others, for example dorsomedial frontal cortex (dmFC), anterior insula cortex (AIC), and periaqueductal gray (PAG). Moreover, the response of other regions implicated in signaling reward, for example ventromedial prefrontal cortex (vmPFC) or posterior cingulate cortex (PCC), has not been systematically examined.

EXPERIMENTAL DESIGN

Functional magnetic resonance imaging utilizing parametric modulation was conducted on 21 healthy adults participating in a social exchange paradigm.

PRINCIPAL OBSERVATIONS

Participants showed significant positive modulation of activity as a function of delivered punishment in caudate, dmFC, AIC, and PAG; that is, higher punishments by participants of unsatisfactory offers were associated with increasing activity within these regions. However, participants showed significant negative modulation of activity as a function of delivered punishment in vmPFC and PCC; increases in punishment level by participants were associated with decreases in activity within these regions.

CONCLUSIONS

The current data question whether caudate activity when punishing unfair offers should be considered to indicate the reward value of this punishment. Instead, this activity, in conjunction with activity within dmFC, AIC, and PAG, may represent the organization of an untypical, punishing response that represents a reactive aggressive response to provocation. Notably, an inverse, regulatory relationship between vmPFC and PAG activity has been previously implicated in the context of another stimulus for reactive aggression; looming threat (Mobbs et al. [2007]: Science 317:1079-1083).

Distinct neural activation patterns underlie economic decisions in high and low psychopathy scorers

Psychopathic traits affect social functioning and the ability to make adaptive decisions in social interactions. This study investigated how psychopathy affects the neural mechanisms that are recruited to make decisions in the ultimatum game. Thirty-five adult participants recruited from the community underwent functional magnetic resonance imaging scanning while they performed the ultimatum game under high and low cognitive load. Across load conditions, high psychopathy scorers rejected unfair offers in the same proportion as low scorers, but perceived them as less unfair. Among low scorers, the perceived fairness of offers predicted acceptance rates, whereas in high scorers no association was found. Imaging results revealed that responses in each group were associated with distinct patterns of brain activation, indicating divergent decision mechanisms. Acceptance of unfair offers was associated with dorsolateral prefrontal cortex activity in low scorers and ventromedial prefrontal cortex activity in high scorers. Overall, our findings point to distinct motivations for rejecting unfair offers in individuals who vary in psychopathic traits, with rejections in high psychopathy scorers being probably induced by frustration. Implications of these results for models of ventromedial prefrontal cortex dysfunction in psychopathy are discussed.

Effects of video game playing on cerebral blood flow in young adults: a SPECT study

To study the impact of video game playing on the human brain, the effects of two video games playing on cerebral blood flow (CBF) in young adults were determined. Thirty healthy subjects comprising 18 males and 12 females who were familiar with video game playing were recruited. Each subject underwent three sessions of single photon emission computed tomography (SPECT) with a bolus injection of 20 mCi (99m)Tc ECD IV to measure their CBF. The first measurement was performed as baseline, the second and third measurements were performed after playing two different video games for 30 min, respectively. Statistic parametric mapping (SPM2) with Matlab 6.5 implemented on a personal computer was used for image analysis. CBF was significantly decreased in the prefrontal cortex and significantly increased in the temporal and occipital cortices after both video games playing. Furthermore, decreased CBF in the anterior cingulate cortex (ACC) which was significantly correlated with the number of killed characters was found after the violent game playing. The major finding of hypo-perfusion in prefrontal regions after video game playing is consistent with a previous study showing reduced or abnormal prefrontal cortex functions after video game playing. The second finding of decreased CBF in the ACC after playing the violent video game provides support for a previous hypothesis that the ACC might play a role in regulating violent behavior.

The neurobiology of abnormal manifestations of aggression--a review of hypothalamic mechanisms in cats, rodents, and humans

Aggression research was for long dominated by the assumption that aggression-related psychopathologies result from the excessive activation of aggression-promoting brain mechanisms. This assumption was recently challenged by findings with models of aggression that mimic etiological factors of aggression-related psychopathologies. Subjects submitted to such procedures show abnormal attack features (mismatch between provocation and response, disregard of species-specific rules, and insensitivity toward the social signals of opponents). We review here 12 such laboratory models and the available human findings on the neural background of abnormal aggression. We focus on the hypothalamus, a region tightly involved in the execution of attacks. Data show that the hypothalamic mechanisms controlling attacks (general activation levels, local serotonin, vasopressin, substance P, glutamate, GABA, and dopamine neurotransmission) undergo etiological factor-dependent changes. Findings suggest that the emotional component of attacks differentiates two basic types of hypothalamic mechanisms. Aggression associated with increased arousal (emotional/reactive aggression) is paralleled by increased mediobasal hypothalamic activation, increased hypothalamic vasopressinergic, but diminished hypothalamic serotonergic neurotransmission. In aggression models associated with low arousal (unemotional/proactive aggression), the lateral but not the mediobasal hypothalamus is over-activated. In addition, the anti-aggressive effect of serotonergic neurotransmission is lost and paradoxical changes were noticed in vasopressinergic neurotransmission. We conclude that there is no single 'neurobiological road' to abnormal aggression: the neural background shows qualitative, etiological factor-dependent differences. Findings obtained with different models should be viewed as alternative mechanisms rather than conflicting data. The relevance of these findings for understanding and treating of aggression-related psychopathologies is discussed. This article is part of a Special Issue entitled 'Extrasynaptic ionotropic receptors'.

Neural correlates of risk taking in violent criminal offenders characterized by emotional hypo- and hyper-reactivity

Recent approaches suggest that emotional reactivity can be used to differentiate between subgroups of individuals who are at risk for showing elevated levels of aggression and violence. In this study, we examined how emotion governs decision making within two subgroups of antisocial criminal offenders with either emotional hypo- or hyper-reactivity compared with healthy, noncriminal controls. Offenders were recruited from high-security forensic treatment facilities and penal institutions and underwent functional magnetic resonance imaging during a financial decision-making task. In this task, participants were required to choose between low-risk (bonds) and high-risk alternatives (stocks). Bonds were always the safe choice; stocks could win or lose, with a varying degree of uncertainty. We found that emotionally hypo-reactive offenders differed most from healthy controls by showing diminished neural activation in the rostral anterior cingulate cortex in response to uncertainty as well as decreased activity in the prefrontal cortex when trying to regulate their behavior accordingly (i.e., when consistently choosing "safe alternatives"). Hence, the data indicate that emotionally hypo-reactive offenders (with psychopathic traits) constitute a special subgroup within antisocial offenders characterized in particular by a limited capacity to emotionally represent uncertainty and to anticipate punishment.

Intrinsic limbic and paralimbic networks are associated with criminal psychopathy

BACKGROUND

Psychopathy is a personality disorder associated with impairments in decision-making, empathy, and impulsivity. Recent brain imaging studies suggest that psychopathy is associated with abnormalities in limbic/paralimbic brain regions. To date, no studies have examined functional brain connectivity measures using independent component analyses (ICA) in adults with psychopathy. Here, we test hypotheses regarding paralimbic connectivity in adult incarcerated individuals stratified by psychopathy scores.

METHODS

One hundred and two prison inmates were rated using the Hare Psychopathy Checklist-Revised (PCL-R). FMRI data were collected while subjects performed an auditory target detection "oddball" task. FMRI data were analyzed using group ICA to identify functional networks responding to the oddball task correlating with psychopathy scores.

RESULTS

Components demonstrating significant correlations with psychopathy included a default mode network, a frontoparietal component, and a visual/posterior cingulate component. Modulation trends correlated strongly with factor 2 (impulsivity) and total PCL-R scores in the frontoparietal and visual/posterior cingulate networks, and with factor 1 (affective) scores within the default mode network. The posterior cingulate region factored significantly in the modulation trends observed.

CONCLUSION

Consistent with the hypothesis of limbic/paralimbic abnormalities associated with psychopathy, modulation trends correlated strongly with PCL-R scores. There is strong evidence to implicate the posterior cingulate in aberrant functional connectivity associated with the manifestation of psychopathic symptoms. Future investigations comparing functional trends associated with the posterior cingulate in psychopathic subjects may provide further insight into the manifestation of this disorder.

The psychopath magnetized: insights from brain imaging

Psychopaths commit a disproportionate amount of violent crime, and this places a substantial economic and emotional burden on society. Elucidation of the neural correlates of psychopathy may lead to improved management and treatment of the condition. Although some methodological issues remain, the neuroimaging literature is generally converging on a set of brain regions and circuits that are consistently implicated in the condition: the orbitofrontal cortex, amygdala, and the anterior and posterior cingulate and adjacent (para)limbic structures. We discuss these findings in the context of extant theories of psychopathy and highlight the potential legal and policy implications of this body of work.

The role of prefrontal cortex in psychopathy

Psychopathy is a personality disorder characterized by remorseless and impulsive antisocial behavior. Given the significant societal costs of the recidivistic criminal acti\xadvity associated with the disorder, there is a pressing need for more effective treatment strategies and, hence, a better understanding of the psychobiological mechanisms underlying the disorder. The prefrontal cortex (PFC) is likely to play an important role in psychopathy. In particular, the ventromedial and anterior cingulate sectors of PFC are theorized to mediate a number of social and affective decision-making functions that appear to be disrupted in psychopathy. This article provides a critical summary of human neuroimaging data implicating prefrontal dysfunction in psychopathy. A growing body of evidence associates psychopathy with structural and functional abnormalities in ventromedial PFC and anterior cingulate cortex. Although this burgeoning field still faces a number of methodological challenges and outstanding questions that will need to be resolved by future studies, the research to date has established a link between psychopathy and PFC.

Temporal and frontal lobe initiation and regulation of the top-down escalation of anger and aggression

The widespread, across-species strategy of stagewise escalation of aggression in agonistic encounters can be understood in terms of resource capture and control with least risk and cost. Human anger likely follows similar principles. As an adaptive phenomenon, escalation may involve particular neural circuitry. To advance beyond a standard view that the frontal lobe tonically inhibits subcortical circuits of aggression, a model is proposed which starts with the general rostrally directed flow of information in the brain. Earlier stage processing of visual and auditory input is transmitted from posterior and middle temporal cortices to anterior temporal lobe where rudimentary appraisals of threat and provocation are developed. These directly but diffusely activate cortical/subcortical anger/aggression response systems. At the same time, the anterior temporal loci transmit the modality-specific perceptual information to orbito-frontal cortex where it is integrated with information about, e.g., the opponent's relative dominance/social status and evaluated for likelihood of potential rewards and punishments associated with different modes of responding and so forth. These frontal areas then impose an inhibitory gating or modulation and focusing of activity initiated by the anterior temporal loci through their projections to GABAergic interneurons in the same cortical/subcortical circuits. Escalation occurs as the inhibition imposed by the frontal areas is progressively lifted. Exploration of the implications, applications and hypotheses flowing from this model will improve our understanding of the biologically important and socially significant phenomena of escalation.

Investigating the neural correlates of psychopathy: a critical review

In recent years, an increasing number of neuroimaging studies have sought to identify the brain anomalies associated with psychopathy. The results of such studies could have significant implications for the clinical and legal management of psychopaths, as well as for neurobiological models of human social behavior. In this article, we provide a critical review of structural and functional neuroimaging studies of psychopathy. In particular, we emphasize the considerable variability in results across studies, and focus our discussion on three methodological issues that could contribute to the observed heterogeneity in study data: (1) the use of between-group analyses (psychopaths vs non-psychopaths) as well as correlational analyses (normal variation in 'psychopathic' traits), (2) discrepancies in the criteria used to classify subjects as psychopaths and (3) consideration of psychopathic subtypes. The available evidence suggests that each of these issues could have a substantial effect on the reliability of imaging data. We propose several strategies for resolving these methodological issues in future studies, with the goal of fostering further progress in the identification of the neural correlates of psychopathy.

Identification of psychopathic individuals using pattern classification of MRI images

BACKGROUND

Psychopathy is a disorder of personality characterized by severe impairments of social conduct, emotional experience, and interpersonal behavior. Psychopaths consistently violate social norms and bring considerable financial, emotional, or physical harm to others and to society as a whole. Recent developments in analysis methods of magnetic resonance imaging (MRI), such as voxel-based-morphometry (VBM), have become major tools to understand the anatomical correlates of this disorder. Nevertheless, the identification of psychopathy by neuroimaging or other neurobiological tools (e.g., genetic testing) remains elusive.

METHODS/PRINCIPAL FINDINGS

The main aim of this study was to develop an approach to distinguish psychopaths from healthy controls, based on the integration between pattern recognition methods and gray matter quantification. We employed support vector machines (SVM) and maximum uncertainty linear discrimination analysis (MLDA), with a feature-selection algorithm. Imaging data from 15 healthy controls and 15 psychopathic individuals (7 women in each group) were analyzed with SPM2 and the optimized VBM preprocessing routines. Participants were scanned with a 1.5 Tesla MRI system. Both SVM and MLDA achieved an overall leave-one-out accuracy of 80%, but SVM mapping was sparser than using MLDA. The superior temporal sulcus/gyrus (bilaterally) was identified as a region containing the most relevant information to separate the two groups.

CONCLUSION/SIGNIFICANCE

These results indicate that gray matter quantitative measures contain robust information to predict high psychopathy scores in individual subjects. The methods employed herein might prove useful as an adjunct to the established clinical and neuropsychological measures in patient screening and diagnostic accuracy.