Emotion and personal space: Neural correlates of approach-avoidance tendencies to different facial expressions as a function of coldhearted psychopathic traits

Close encounters: Interpersonal proximity amplifies social appraisals

Social appraisals reflect the rapid integration of available perceptual information with broader contextual factors (e.g., intentions). While interpersonal distance affects both information availability and social context, how it changes trait impressions remains unknown. Over four experiments, we used a novel paradigm to address this question. In Experiment 1, we assessed participants' attributions of attractiveness, competence, dominance and trustworthiness of life size full body images of people when they appeared at near (1 m) and far (4 m) distances. Proximity amplified the relative magnitude of both positive and negative socio-evaluative impressions. However, this effect of proximity leading to more extreme positive or negative ratings was selectively weaker for aesthetic (attractiveness) judgements. In Experiment 2 (size) and Experiment 3 (spatial frequency), we held distance constant while manipulating visual cues relating to implied distance, revealing broadly similar results to Experiment 1. In Experiment 4, we used the interpersonal comfort distance paradigm to confirm that our life-sized projected images elicited similar comfort distance to interacting with a real person, helping to validate our general approach. These findings demonstrate the crucial role of interpersonal distance in impression judgements.

Altered representation of peripersonal and interpersonal space in psychopathology

The space surrounding the body, and the regulation of this buffer zone play a central role in adaptive behavior, with direct implications for psychopathology. The physical distance that we choose to maintain between ourselves and others for social comfort is known as Interpersonal Distance (IPD), whereas the action space that marks the perceptual border between the self and the external world is known as Peripersonal Space (PPS ). While both IPD and PPS represent personal space, they are distinct constructs, each associated with different methodologies. Here we review the existing literature on IPD and PPS to elucidate their distinct and common contributions to psychiatric conditions including schizophrenia, autism, anxiety, and others. Altered representation and regulation of IPD and PPS were associated with clinical symptoms and social impairments across a wide range of psychiatric disorders, underscoring the important role of the self-other boundary and personal space regulation in adaptive social behavior. Future research should clarify the relationship between IPD and PPS and specify risk factors for self-other boundary dysregulation and associated psychopathologies.

The convergence between defence and care in mammals

The motivations to protect oneself and others have often been seen as conflicting. Here, we discuss recent evidence that self-defensive mechanisms may in fact be recruited to enable the helping of others. In some instances, the defensive response to a threat may even be more decisive in promoting helping than the response to a conspecific's distress (as predicted by empathy-altruism models). In light of this evidence, we propose that neural mechanisms implicated in self-defence may have been repurposed through evolution to enable the protection of others, and that defence and care may be convergent rather than conflicting functions. Finally, we present and discuss a working model of the shared brain mechanisms implicated in defence of both self and others.

The impact of acute violent videogame exposure on neurocognitive markers of empathic concern

Research examining the purported association between violent gaming and aggression remains controversial due to concerns related to methodology, unclear neurocognitive mechanisms, and the failure to adequately consider the role of individual differences in susceptibility. To help address these concerns, we used fMRI and an emotional empathy task to examine whether acute and cumulative violent gaming exposure were associated with abnormalities in emotional empathy as a function of trait-empathy. Emotional empathy was targeted given its involvement in regulating not only aggression, but also other important social functions such as compassion and prosocial behaviour. We hypothesized that violent gaming exposure increases the risk of aberrant social behaviour by altering the aversive value of distress cues. Contrary to expectations, neither behavioural ratings nor empathy-related brain activity varied as a function of violent gaming exposure. Notably, however, activation patterns in somatosensory and motor cortices reflected an interaction between violent gaming exposure and trait empathy. Thus, our results are inconsistent with a straightforward relationship between violent gaming exposure and reduced empathy. Furthermore, they highlight the importance of considering both individual differences in susceptibility and other aspects of cognition related to social functioning to best inform public concern regarding safe gaming practices.

Neuroanatomical correlates of peripersonal space: bridging the gap between perception, action, emotion and social cognition

Peripersonal space (PPS) is a construct referring to the portion of space immediately surrounding our bodies, where most of the interactions between the subject and the environment, including other individuals, take place. Decades of animal and human neuroscience research have revealed that the brain holds a separate representation of this region of space: this distinct spatial representation has evolved to ensure proper relevance to stimuli that are close to the body and prompt an appropriate behavioral response. The neural underpinnings of such construct have been thoroughly investigated by different generations of studies involving anatomical and electrophysiological investigations in animal models, and, recently, neuroimaging experiments in human subjects. Here, we provide a comprehensive anatomical overview of the anatomical circuitry underlying PPS representation in the human brain. Gathering evidence from multiple areas of research, we identified cortical and subcortical regions that are involved in specific aspects of PPS encoding.We show how these regions are part of segregated, yet integrated functional networks within the brain, which are in turn involved in higher-order integration of information. This wide-scale circuitry accounts for the relevance of PPS encoding in multiple brain functions, including not only motor planning and visuospatial attention but also emotional and social cognitive aspects. A complete characterization of these circuits may clarify the derangements of PPS representation observed in different neurological and neuropsychiatric diseases.

Away from the herd: loneliness as a dysfunction of social alignment

The tendency of all humans to experience loneliness at some point in their lives implies that it serves an adaptive function. Building on biological theories of herding in animals, according to which collective movement emerges from local interactions that are based on principles of attraction, repulsion and alignment, we propose an approach that synthesizes these principles with theories of loneliness in humans. We present here the 'herding model of loneliness' that extends these principles into the psychological domain. We hold that these principles serve as basic building blocks of human interactions and propose that distorted attraction and repulsion tendencies may lead to inability to align properly with others, which may be a core component in loneliness emergence and perpetuation. We describe a neural model of herding in humans and suggest that loneliness may be associated with altered interactions between the gap/error detection, reward signaling, threat and observation-execution systems. The proposed model offers a framework to predict the behavior of lonely individuals and thus may inform intervention designs for reducing loneliness intensity.

Keeping distance or getting closer: How others' emotions shape approach-avoidance postural behaviors and preferred interpersonal distance

Understanding the influence of emotions on social interactions is important for a global understanding of the dynamics of human behavior. In this study, we investigated the interplay between emotions, spontaneous approach or avoidance tendencies, and the regulation of interpersonal distance. Fifty-seven healthy adults participated in a three-part experiment involving exposure to approaching or withdrawing emotional faces (neutral, happy, sad, fearful, disgusted, angry). The sequence began with an initial computerized stop-distance task, followed by a postural task in which participants' approach or avoidance tendencies were quantified via center of pressure (CoP-Y) displacements on a force platform, and concluded with a final computerized stop-distance task. Our findings revealed a gradient in postural responses, with the most forward CoP-Y displacements for neutral and happy faces, indicative of approach tendencies. These were followed by lesser forward displacements for sad and fearful faces, and most pronounced backward displacements for disgusted and angry faces, indicating avoidance. Furthermore, we observed modulations in participants' preferred interpersonal distance based on emotional cues, with neutral and happy faces associated with shorter distances, and disgusted and angry faces linked to larger distances. Despite these similar results, no direct correlation was found between CoP-Y and preferred interpersonal distance, underscoring a dissociation between spontaneous and voluntary social behaviors. These results contribute to a better understanding of how emotional expressions shape social interactions and underscore the importance of considering emotional cues, postural action tendencies, and interpersonal distance in facilitating successful social interactions.

Generalization of the modulatory effect of social interaction on personal space

Introduction

Personal space (PS) is a safe area around an individual's body that affects spatial distance when socially interacting with others. Previous studies have shown that social interaction may modulate PS. However, these findings are often confounded by the effects of familiarization. Furthermore, whether the potential regulatory effects of social interaction on PS can be generalized from interacting confederates to strangers remains unclear.

Methods

To answer these questions, we enrolled 115 participants in a carefully designed experiment.

Results

We found that prosocial interaction in the form of a cooperative task effectively reduced PS, and this regulatory effect could be generalized from interacting confederates to non-interacting confederates.

Discussion

These findings deepen our understanding of PS regulation and may be aid in the diagnosis and rehabilitation of dysfunctional social behaviors.

The "(a)moral brain": When things go wrong

In the past decades, a growing interest of neuroscience on moral judgment and decision-making has shed new light on the neurobiological correlates of human morality. It is now understood that moral cognition relies on a complex integration of cognitive and affective information processes that implicate a widely distributed brain network. Moral cognition relies on the coordination of several domain-general processes, subserved by domain-general neural networks, rather than a specific moral cognition system subserved by a specific neural network. In this chapter, we will first briefly review what is currently known about the "moral brain," i.e., the network of brain regions consistently implicated in studies of moral cognition, which include decision-making, affective processing, mentalizing, and perspective-taking processing regions. We will then review the evidence of the impairments found in this network in individuals with psychopathy, a condition whose characteristics indicate profound disturbances in appropriate moral processing. We will present data from neuroimaging studies with forensic/clinical, general population, as well as child and adolescent samples, which seem to converge to support the notion that the moral dysfunction observed in individuals with psychopathy may stem from a disruption of affective components of moral processing rather than from an inability to compute moral judgments per se.

Neural and behavioral alterations of a real-time interpersonal distance (IPD) development process in differing social status interactions

Background

Evidence showed neural changes in interpersonal distance (IPD) interaction, and neural activities are affected by relationships (such as friends or strangers). Behavior studies proved that social status strongly affects IPD between two persons. However, how the differing social status impacts neural alterations in the IPD interactions remains unknown.

Objectives

The teacher-student relationship is a typical representation of the difference in social status. The present study aims to investigate the IPD performance and brain processes underlying real-time differing social status during the development process from teacher-student interactions.

Materials and methods

We designed three within-subject experiments corresponding to the inclusion, control, and affection stages of IPD. Altogether, 38 valid healthy participants participated in three experiments with a teacher (differing social status condition, DS condition) and a peer student (peer social status condition, PS condition) separately. This study employed functional near-infrared spectroscopy (fNIRS) and modified real-time stop-distance paradigms to record IPD performance and neural processes.

Results

For IPD performance, significantly larger IPD gaps were shown in the DS condition than in the PS condition, and IPD feedback affected IPD performance. For neural alterations, activated frontopolar area (FPA, BA10), dorsolateral prefrontal cortex (DLPFC, BA9/BA46), and Broca’s area (BA45) were observed across the IPD stages. Importantly, brain activation shifts with the development of IPD. In addition, results showed that differences in Oxy-Hb changes were located in the FPA (BA10), DLPFC (BA9/BA46), and Broca’s area (BA45) between the DS and PS conditions across IPD stages. Additionally, negative correlations were found between Oxy-Hb changes and IPD performance.

Conclusion

We propose prefrontal cortex (PFC) and Broca’s area involvement in IPD interactions, initially focusing on evaluation and action periods, and later on IPD-evaluation processes after feedback. In addition, a difference in Oxy-Hb activities implies the complexity of relationships and social status in IPD interactions.

A neuroimaging study of interpersonal distance in identical and fraternal twins

Keeping appropriate interpersonal distance is an evolutionary conserved behavior that can be adapted based on learning. Detailed knowledge on how interpersonal space is represented in the brain and whether such representation is genetically influenced is lacking. We measured brain function using functional magnetic resonance imaging in 294 twins (71 monozygotic, 76 dizygotic pairs) performing a distance task where neural responses to human figures were compared to cylindrical blocks. Proximal viewing distance of human figures was compared to cylinders facilitated responses in the occipital face area (OFA) and the superficial part of the amygdala, which is consistent with these areas playing a role in monitoring interpersonal distance. Using the classic twin method, we observed a genetic influence on interpersonal distance related activation in the OFA, but not in the amygdala. Results suggest that genetic factors may influence interpersonal distance monitoring via the OFA whereas the amygdala may play a role in experience‐dependent adjustments of interpersonal distance.

Face in collision: emotional looming stimuli modulate interpersonal space across development and gender

Basic visual functions have evolved to allow for rapid detection of dynamic stimuli in our surrounding environment. In particular, looming stimuli are of relevance because they are expected to enter the individual’s interpersonal space representing a potential threat. Different studies showed that emotions can modulate the perception of visual looming stimuli and the borders of interpersonal space, defined as the area around the body that individuals maintain between themselves and others during social interactions. Here, we investigated how emotions modulate the perception and the physiological correlates of interpersonal space and whether such indexes change across age and gender. Children and adults were asked to quickly react to emotional looming stimuli while measuring their skin conductance response (SCR). We found that emotional looming stimuli shrink the borders of interpersonal space of males more than females, and that this pattern does not change with age. In addition, adults reacted faster to angry than happy and neutral faces, which is in line with the notion that threatening stimuli capture attention more quickly than other types of emotional stimuli. However, this was not observed in children, suggesting that experience with negative stimuli, rather than the evolutionary meaning they possess, may influence the boundaries of interpersonal space. Overall, our study suggests that interpersonal space is modulated by emotions, but this appears to be modulated by gender and age: while behavioural responses to emotional looming stimuli refine with age, physiological responses are adult-like as early as 5 years of age.

Neural Alterations in Interpersonal Distance (IPD) Cognition and Its Correlation with IPD Behavior: A Systematic Review

Background. Interpersonal distance (IPD) plays a critical role in a human being’s social life, especially during interpersonal interaction, and IPD is non-verbal social information and not only provides silent cues but also provides a secure space for personal relationships. IPD has been a research field of neural studies from the recent decade, researches had provided behavior and neural correlates of IPD. Objectives. This review aims to summarize the experimental paradigms of IPD-neural research, to reveal the neural activity processes associated with it, and to explore the correlation between IPD-neural activity and IPD-behavior. Methods. We conducted a standardized systematic review procedure, including the formal search method be adopted to seek out any type of studies related to IPD and brain, then devised them into categories to make a systematic review. Results. 17 articles met the inclusion criteria of the review, 5 event-related potential (ERP) studies measured the amplitude and latencies of ERPs, and 12 functional magnetic resonance imaging (fMRI) studies provided the neural activation during IPD tasks. In addition, the passive IPD experimental paradigm is the main experimental paradigm for exploring neural activity in IPD cognition, with the parietal lobe, motor areas, prefrontal lobe, and amygdala being the main brain areas involved. Functional connections between the identified brain regions were found and have a moderate correlation with IPD behavior. Conclusions. This review provides the neural activity of the IPD interaction process. However, the insufficient ecological validity of IPD tasks and ignore the initiative of people in IPD interaction. Therefore, there is a large research space on this topic. The work of the current systematic review contributed to linking the external performance and inner neural activities of IPD.

Brain Plasticity Reflects Specialized Cognitive Development Induced by Musical Training

Learning a musical instrument requires a long period of training and might induce structural and functional changes in the brain. Previous studies have shown brain plasticity resulting from training with a musical instrument. However, these studies did not distinguish the effects on brain plasticity of specific musical instruments as they examined the brain of musicians who had learned a single musical instrument/genre and did not control for confounding factors, such as common or interactive effects involved in music training. To address this research gap, the present work investigated musicians who had experience with both a piano and a wind instrument, for example, flute, trumpet, clarinet etc. By examining the difference between the 2 musical instruments in the same subject, we avoided the effects common to all musical instruments and the confounding factors. Therefore, we identified several high-tier brain areas displaying a brain plasticity specific to each musical instrument. Our findings show that learning a musical instrument might result in the development of high cognitive functions reflecting the skills/abilities unique to the instrument played.

The Peripersonal Space in a social world

The PeriPersonal Space (PPS) has been defined as the space surrounding the body, where physical interactions with elements of the environment take place. As our world is social in nature, recent evidence revealed the complex modulation of social factors onto PPS representation. In light of the growing interest in the field, in this review we take a close look at the experimental approaches undertaken to assess the impact of social factors onto PPS representation. Our social world also influences the personal space (PS), a concept stemming from social psychology, defined as the space we keep between us and others to avoid discomfort. Here we analytically compare PPS and PS with the aim of understanding if and how they relate to each other. At the behavioral level, the multiplicity of experimental methodologies, whether well-established or novel, lead to somewhat divergent results and interpretations. Beyond behavior, we review physiological and neural signatures of PPS representation to discuss how interoceptive signals could contribute to PPS representation, as well as how these internal signals could shape the neural responses of PPS representation. In particular, by merging exteroceptive information from the environment and internal signals that come from the body, PPS may promote an integrated representation of the self, as distinct from the environment and the others. We put forward that integrating internal and external signals in the brain for perception of proximal environmental stimuli may also provide us with a better understanding of the processes at play during social interactions. Adopting such an integrative stance may offer novel insights about PPS representation in a social world. Finally, we discuss possible links between PPS research and social cognition, a link that may contribute to the understanding of intentions and feelings of others around us and promote appropriate social interactions.

The Interrelation Between Peripersonal Action Space and Interpersonal Social Space: Psychophysiological Evidence and Clinical Implications

The peripersonal space is an adaptive and flexible interface between the body and the environment that fulfills a dual-motor function: preparing the body for voluntary object-oriented actions to interact with incentive stimuli and preparing the body for defensive responses when facing potentially harmful stimuli. In this position article, we provide arguments for the sensorimotor rooting of the peripersonal space representation and highlight the variables that contribute to its flexible and adaptive characteristics. We also demonstrate that peripersonal space represents a mediation zone between the body and the environment contributing to not only the control of goal-directed actions but also the organization of social life. The whole of the data presented and discussed led us to the proposal of a new theoretical framework linking the peripersonal action space and the interpersonal social space and we highlight how this theoretical framework can account for social behaviors in populations with socio-emotional deficits.

Neural Correlates of Interpersonal Space Permeability and Flexibility in Autism Spectrum Disorder

Previous research indicates that the size of interpersonal space at which the other is perceived as intrusive (permeability) and the ability to adapt interpersonal distance based on contextual factors (flexibility) are altered in Autism Spectrum Disorder (ASD). However, the neurophysiological basis of these alterations remains poorly understood. To fill this gap, we used fMRI and assessed interpersonal space preferences of individuals with ASD before and after engaging in cooperative and non-cooperative social interactions. Compared to matched controls, ASDs showed lower comfort in response to an approaching confederate, indicating preference for larger interpersonal space in autism (altered permeability). This preference was accompanied by reduced activity in bilateral dorsal intraparietal sulcus (dIPS) and left fusiform face area (FFA), regions previously shown to be involved in interpersonal space regulation. Furthermore, we observed differences in effective connectivity among dIPS, FFA, and amygdala in ASDs compared to controls, depending on the level of experienced comfort. No differences between groups were observed in interpersonal space regulation after an experienced social interaction (flexibility). Taken together, the present findings suggest that a dysregulation of the activity and connectivity of brain areas involved in interpersonal space processing may contribute to avoidance of physical proximity and social impairments in ASD.

Effects of Modulated Emotion and Facial Masking Encounter on Personal Distance

In this study, we examined the effects of participants' emotional states on personal space when an approaching person's face was either masked or unmasked. We used the participants' uncomfortable stop-distance as our method of measuring personal space. Inducing a positive emotion narrowed perceived personal space, whereas inducing a negative emotion widened personal space. For both positive and negative emotions, the perceived interpersonal distance was shorter when the approaching face was unmasked than masked. There was no interaction effect on personal space between induced affect and masking or unmasking the approaching face. This study might provide insight into interpersonal behavior during a pandemic juncture.

Molecular and neurocircuitry mechanisms of social avoidance

Humans and animals live in social relationships shaped by actions of approach and avoidance. Both are crucial for normal physical and mental development, survival, and well-being. Active withdrawal from social interaction is often induced by the perception of threat or unpleasant social experience and relies on adaptive mechanisms within neuronal networks associated with social behavior. In case of confrontation with overly strong or persistent stressors and/or dispositions of the affected individual, maladaptive processes in the neuronal circuitries and its associated transmitters and modulators lead to pathological social avoidance. This review focuses on active, fear-driven social avoidance, affected circuits within the mesocorticolimbic system and associated regions and a selection of molecular modulators that promise translational potential. A comprehensive review of human research in this field is followed by a reflection on animal studies that offer a broader and often more detailed range of analytical methodologies. Finally, we take a critical look at challenges that could be addressed in future translational research on fear-driven social avoidance.

The influence of facial expression at perceptual threshold on electrodermal activity and social comfort distance

Interpersonal distance, an essential component of social interaction, is modulated by the emotion conveyed by others and associated physiological response. However, in modern societies with overcrowded and hyperstimulating environments, we can only surreptitiously glimpse the faces of others in order to quickly make behavioral adjustments. How this impacts social interactions is not yet well understood. In the present study, we investigated this issue by testing whether facial expressions that are difficult to identify modify the physiological response (Electrodermal Activity, EDA) and subsequent judgment of interpersonal comfort distance. We recorded participants' EDA while they provided comfort judgments to interpersonal distances with a Point-Light Walker (PLW). The PLW, with an emotionally neutral gait, moved toward and crossed participants at various distances after the latter were exposed to a negative (anger), positive (happiness) or neutral facial expression presented at the perceptual threshold. Bayesian analyses of the data revealed an increase versus decrease of interpersonal comfort distance with the PLW depending on the negative versus positive emotional valence of the facial expression. They also showed an increase in EDA when the approaching PLW violated interpersonal comfort distance after participants were exposed to an angry facial expression. These effects correlated with the subjective assessment of the arousal of facial expressions. Thus, previous exposure to barely visible facial expressions can alter the representation of social comfort space and the physiological response associated with a violation of interpersonal comfort distances, depending on the valence and arousal of the emotional social stimuli.

Aggressive Realism: More Efficient Processing of Anger in Physically Aggressive Individuals

Physically aggressive individuals' heightened tendency to decide that ambiguous faces are angry is thought to contribute to their destructive interpersonal behavior. Although this tendency is commonly attributed to bias, other cognitive processes could account for the emotion-identification patterns observed in physical aggression. Diffusion modeling is a valuable tool for parsing the contributions of several cognitive processes known to influence decision-making, including bias, drift rate (efficiency of information accumulation), and threshold separation (extent of information accumulation). In a sample of 90 incarcerated men, we applied diffusion modeling to an emotion-identification task. Physical aggression was positively associated with drift rate (i.e., more efficient information accumulation) for anger, and drift rate mediated the association between physical aggression and heightened anger identification. Physical aggression was not, however, associated with bias or threshold separation. These findings implicate processing efficiency for anger-related information as a potential mechanism driving aberrant emotion identification in physical aggression.

How interindividual differences shape approach-avoidance behavior: Relating self-report and diagnostic measures of interindividual differences to behavioral measurements of approach and avoidance

Responding to stimuli in ambiguous environments is partially governed by approach-avoidance tendencies. Imbalances in these approach-avoidance behaviors are implicated in many mental disorders including anxiety disorders, phobias and substance use disorders. While factors biasing human behavior in approach-avoidance conflicts have been researched in numerous experiments, a much-needed comprehensive overview integrating those findings is missing. Here, we systematically searched the existing literature on individual differences in task-based approach-avoidance behavior and aggregated the current evidence for the effect of self-reported approach/avoidance traits, anxiety and anxiety disorders, specific phobias, depression, aggression, anger and psychopathy, substance use and related disorders, eating disorders and habits, trauma, acute stress and, finally, hormone levels (mainly testosterone, oxytocin). We highlight consistent findings, underrepresented research areas and unexpected results, and detail the amount of controversy between studies. We discuss potential reasons for ambiguous results in some research areas, offer practical advice for future studies and highlight potential variables such as task-related researcher decisions that may influence how interindividual differences and disorders drive automatic approach-avoidance biases in behavioral experiments.

Neural correlates of social and non-social personal space intrusions: Role of defensive and peripersonal space systems in interpersonal distance regulation

Personal space regulation ensures the maintenance of a margin of safety between the individual and the surrounding world. However, little is known about the specific neural mechanisms implicated in regulating the distance from conspecifics versus non-social stimuli. Here, we investigated the neural correlates of personal space intrusions by social versus non-social stimuli. Thirty volunteers underwent fMRI scanning while viewing approaching or withdrawing faces (Social) and insects/arachnids (Non-social). Preferred distance to the stimuli was assessed behaviourally in a computerized task, and in real life. Results showed that approaching social and non-social stimuli of varying threat levels elicited activation of frontoparietal regions previously linked to peripersonal space, as well as of the midbrain periaqueductal gray, suggesting the engagement of defensive mechanisms by personal space intrusions. However, functional connectivity patterns of the midbrain differed for social and non-social stimuli, with enhanced coupling with the premotor cortex to approaching social stimuli. Additionally, connectivity strength between the midbrain and the premotor cortex was associated with preferred interpersonal distance. These findings highlight a common defensive architecture implicated in personal space regulation to social and non-social stimuli, and the specific neural mechanisms involved in regulating the distance from conspecifics.

A Systematic Literature Review of Neuroimaging of Psychopathic Traits

INTRODUCTION

Core psychopathy is characterized by grandiosity, callousness, manipulativeness, and lack of remorse, empathy, and guilt. It is often comorbid with conduct disorder and antisocial personality disorder (ASPD). Psychopathy is present in forensic as well as prison and general populations. In recent years, an increasing amount of neuroimaging studies has been conducted in order to elucidate the obscure neurobiological etiology of psychopathy. The studies have yielded heterogenous results, and no consensus has been reached.

AIMS

This study systematically reviewed and qualitatively summarized functional and structural neuroimaging studies conducted on individuals with psychopathic traits. Furthermore, this study aimed to evaluate whether the findings from different MRI modalities could be reconciled from a neuroanatomical perspective.

MATERIALS AND METHODS

After the search and auditing processes, 118 neuroimaging studies were included in this systematic literature review. The studies consisted of structural, functional, and diffusion tensor MRI studies.

RESULTS

Psychopathy was associated with numerous neuroanatomical abnormalities. Structurally, gray matter anomalies were seen in frontotemporal, cerebellar, limbic, and paralimbic regions. Associated gray matter volume (GMV) reductions were most pronounced particularly in most of the prefrontal cortex, and temporal gyri including the fusiform gyrus. Also decreased GMV of the amygdalae and hippocampi as well the cingulate and insular cortices were associated with psychopathy, as well as abnormal morphology of the hippocampi, amygdala, and nucleus accumbens. Functionally, psychopathy was associated with dysfunction of the default mode network, which was also linked to poor moral judgment as well as deficient metacognitive and introspective abilities. Second, reduced white matter integrity in the uncinate fasciculus and dorsal cingulum were associated with core psychopathy. Third, emotional detachment was associated with dysfunction of the posterior cerebellum, the human mirror neuron system and the Theory of Mind denoting lack of empathy and persistent failure in integrating affective information into cognition.

CONCLUSIONS

Structural and functional aberrancies involving the limbic and paralimbic systems including reduced integrity of the uncinate fasciculus appear to be associated with core psychopathic features. Furthermore, this review points towards the idea that ASPD and psychopathy might stem from divergent biological processes.