The Social Salience Hypothesis of Oxytocin

Epigenetic Transmission of Maternal Behavior: Impact on the Neurobiological System of Healthy Mothers

Quality of maternal caregiving not only impacts children's development but can also result in heritable changes in gene expression (i.e., in an epigenetic manner). Consequently, when women become mothers, they adopt parenting behavior similar to that they received at family of origin. This transgenerational transmission of maternal behavior may also be associated with changes in the neurobiological system of future mothers. This review aims to highlight the effect quality of perceived parenting has on maternal behavior and the neurobiological system of mothers, specifically the oxytocin system, brain morphology and brain function. This would likely help in finding biomarkers that profile the impact of perceived parenting on mothers, and thus allow identification of mothers who experience poor-quality parenting for intervention.

Oxytocin Modulates the Intrinsic Dynamics Between Attention-Related Large-Scale Networks

Attention and salience processing have been linked to the intrinsic between- and within-network dynamics of large-scale networks engaged in internal (default network [DN]) and external attention allocation (dorsal attention network [DAN] and salience network [SN]). The central oxytocin (OXT) system appears ideally organized to modulate widely distributed neural systems and to regulate the switch between internal attention and salient stimuli in the environment. The current randomized placebo (PLC)-controlled between-subject pharmacological resting-state fMRI study in N = 187 (OXT, n = 94; PLC, n = 93; single-dose intranasal administration) healthy male and female participants employed an independent component analysis approach to determine the modulatory effects of OXT on the within- and between-network dynamics of the DAN-SN-DN triple network system. OXT increased the functional integration between subsystems within SN and DN and increased functional segregation of the DN with both attentional control networks (SN and DAN). Whereas no sex differences were observed, OXT effects on the DN-SN interaction were modulated by autistic traits. Together, the findings suggest that OXT may facilitate efficient attention allocation by modulating the intrinsic functional dynamics between DN components and large-scale networks involved in external attentional demands (SN and DAN).

Oxytocin and excitation/inhibition balance in social recognition

Social recognition is the sensitive domains of complex behavior critical for identification, interpretation and storage of socially meaningful information. Social recognition develops throughout childhood and adolescent, and is affected in a wide variety of psychiatric disorders. Recently, new data appeared on the molecular mechanisms of these processes, particularly, the excitatory-inhibitory (E/I) ratio which is modified during development, and then E/I balance is established in the adult brain. While E/I imbalance has been proposed as a mechanism for schizophrenia, it also seems to be the common mechanism in autism spectrum disorder (ASD). In addition, there is a strong suggestion that the oxytocinergic system is related to GABA-mediated E/I control in the context of brain socialization. In this review, we attempt to summarize the underpinning molecular mechanisms of E/I balance and its imbalance, and related biomarkers in the brain in healthiness and pathology. In addition, because there are increasing interest on oxytocin in the social neuroscience field, we will pay intensive attention to the role of oxytocin in maintaining E/I balance from the viewpoint of its effects on improving social impairment in psychiatric diseases, especially in ASD.

Intimate partner violence moderates the association between oxytocin and reactivity to dyadic conflict among couples

Emerging literature indicates individual and contextual differences impact response to oxytocin (OT). Intimate partner violence (IPV) is one chronic stressor that may moderate OT response. To test the hypothesis that IPV moderates the association between OT and reactivity to a dyadic conflict task, data from a larger randomized controlled study was collected from heterosexual couples (N = 60 individuals; 30 couples) at high risk for IPV due to substance misuse. Partners within each dyad completed a 10-minute dyadic conflict task in the laboratory, and then self-administered a single dose of OT (40 IU) or placebo. Forty-five minutes later, participants completed another 10-minute dyadic conflict task. Stress reactivity was measured before and after the second conflict task using neuroendocrine (i.e., salivary cortisol), physiological (i.e., skin conductance), and subjective responses. Couple conflict behaviors were observed during the conflict tasks and assessed using a validated coding system. Among women, physical IPV modulated skin conductance in those administered OT, and OT interacted with physical and psychological IPV to yield less positive subjective and behavioral responses. No main or moderating effects were found for men. Findings support emerging literature on sex differences in response to OT. Future research is needed to effectively translate OT into therapeutic intervention.

Maternal nurturing experience affects the perception and recognition of adult and infant facial expressions

The perception and recognition of facial expressions are crucial for parenting. This study investigated whether and how maternal nurturing experience and trait anxiety influence the perception and recognition of infant and adult facial expressions. This was assessed by comparing the performance of primiparous mothers (n = 25) and non-mothers (n = 28) on an emotional face perception task. Trait anxiety was measured using the Japanese version of the State-Trait Anxiety Inventory (STAI). We found that mothers had higher recognition accuracy for facial expressions, but only of adults, not infants. Moreover, as trait anxiety increased, so did mothers’ sensitivity in perceiving facial expressions of both infants and adults. These findings suggest that maternal nurturing experience does enhance the recognition of adult emotional expressions, and an optimal level of maternal trait anxiety may enhance mothers’ sensitivity toward infants’ and adults’ emotional signals.

Oxytocin Receptor Gene (OXTR) and Deviant Peer Affiliation: A Gene-Environment Interaction in Adolescent Antisocial Behavior

Although the oxytocin receptor gene (OXTR) is involved in aggression and social affiliation, it has not been examined in gene-environment interaction studies. This longitudinal study examined the effect of genetic variants in OXTR and its gene-environment interaction with perceived deviant peer affiliation in the trajectories of antisocial behavior in 323 adolescents (182 males) from 13 to 18 years. Annual assessments of reactive and proactive aggression, delinquency, and friends' delinquency, as well as DNA at age 17 were collected. Gene-based tests yielded no main effect of OXTR, but revealed a significant gene-environment interaction in proactive aggression and delinquency. Variation in the OXTR might affect the influence of deviant peer affiliation on antisocial behavior, contributing to a better understanding of individual differences in antisocial behavior.

Modelling Adaptation through Social Allostasis: Modulating the Effects of Social Touch with Oxytocin in Embodied Agents

Social allostasis is a mechanism of adaptation that permits individuals to dynamically adapt their physiology to changing physical and social conditions. Oxytocin (OT) is widely considered to be one of the hormones that drives and adapts social behaviours. While its precise effects remain unclear, two areas where OT may promote adaptation are by affecting social salience, and affecting internal responses of performing social behaviours. Working towards a model of dynamic adaptation through social allostasis in simulated embodied agents, and extending our previous work studying OT-inspired modulation of social salience, we present a model and experiments that investigate the effects and adaptive value of allostatic processes based on hormonal (OT) modulation of affective elements of a social behaviour. In particular, we investigate and test the effects and adaptive value of modulating the degree of satisfaction of tactile contact in a social motivation context in a small simulated agent society across different environmental challenges (related to availability of food) and effects of OT modulation of social salience as a motivational incentive. Our results show that the effects of these modulatory mechanisms have different (positive or negative) adaptive value across different groups and under different environmental circumstance in a way that supports the context-dependent nature of OT, put forward by the interactionist approach to OT modulation in biological agents. In terms of simulation models, this means that OT modulation of the mechanisms that we have described should be context-dependent in order to maximise viability of our socially adaptive agents, illustrating the relevance of social allostasis mechanisms.

Empathy in pregnant women and new mothers: a systematic literature review

OBJECTIVE

This systematic review explores changes in perinatal empathy and influence on maternal behaviours and child development.

BACKGROUND

The well-being and development of infants are commonly linked to their mothers' capacity for empathy. However, characteristic changes during pregnancy and childbirth including sleep deprivation, mood and cognitive difficulties may disrupt empathic processing.

METHODS

Original research papers (n = 7413) published in English language peer-reviewed academic journals were obtained by searching four electronic databases PsycINFO, PubMed, Scopus and CINAHL. Inclusion criteria were studies reporting empathy of women in the period from pregnancy to 12 months postpartum. Empathy was operationalised as a general tendency of empathic emotional responding and cognitive perspective taking. Thirteen studies were systematically assessed using the Critical Appraisal Skills Programme criteria.

RESULTS

Impaired empathy in mothers, due most notably to high personal distress, was associated with risk of neglect or maltreatment of children and was partially explained by mothers' aversive response to infant crying.

CONCLUSION

Few studies present empathy as a central theme. There is a paucity of definitional parameters and theoretical linkages and over-reliance on brief self-report indices of empathy. Future studies need to be theory based, incorporate experimental approaches, and provide greater sampling diversity toadvance our understanding of empathy in perinatal women.

Oxytocin receptor activation in the basolateral complex of the amygdala enhances discrimination between discrete cues and promotes configural processing of cues

Oxytocin (OT) is a neuropeptide which influences the expression of social behavior and regulates its distribution according to the social context - OT is associated with increased pro-social effects in the absence of social threat and defensive aggression when threats are present. The present experiments investigated the effects of OT beyond that of social behavior by using a discriminative Pavlovian fear conditioning protocol with rats. In Experiment 1, an OT receptor agonist (TGOT) microinjected into the basolateral amygdala facilitated the discrimination between an auditory cue that signaled shock and another auditory cue that signaled the absence of shock. This TGOT-facilitated discrimination was replicated in a second experiment where the shocked and non-shocked auditory cues were accompanied by a common visual cue. Conditioned responding on probe trials of the auditory and visual elements indicated that TGOT administration produced a qualitative shift in the learning mechanisms underlying the discrimination between the two compounds. This was confirmed by comparisons between the present results and simulated predictions of elemental and configural associative learning models. Overall, the present findings demonstrate that the neuromodulatory effects of OT influence behavior outside of the social domain.

Effect of the interaction between oxytocin receptor gene polymorphism (rs53576) and stressful life events on aggression in Chinese Han adolescents

OBJECTIVES

Accumulating evidence suggests that stressful life events are associated with increased risk for aggressive behavior in adolescents; however, aggressive reactions to life stressors exhibit large individual differences. The present study sought to examine whether the interaction between a single nucleotide polymorphism (SNP [rs53576]) within the oxytocin receptor gene (OXTR) and stressful life events is related to aggression in Chinese Han adolescents.

METHODS

A total of 197 Chinese Han adolescents (14-17 years of age) were included in this study. Aggression was assessed using the 12-item short version of Buss and Perry Aggression Questionnaire. Stressful life events during the past 12 months were assessed using the Adolescent Self-Rating Life Events Checklist. Genomic DNA was extracted from saliva and buccal cells from each individual.

RESULTS

Multivariate analysis of variance yielded a significant interaction between OXTR rs53576 SNP and life stress (F = 2.449, p = 0.043, partial η2 = 0.051) and of sex × SNP × life stress (F = 3.144, p = 0.016, partial η2 = 0.064). High life stress during the past 12 months was associated with high levels of physical aggression and hostility in OXTR rs53576 homozygous AA adolescents but not in G-carrier adolescents. In boys, homozygous AA individuals in the high life stress group reported significantly higher levels of physical aggression than participants in the other three groups; the interaction, however, was not significant in girls.

CONCLUSIONS

This study, which analyzed a specific gene-environment interaction, demonstrated that AA OXTR rs53576 homozygosity may correlate with higher levels of aggression under high life stress conditions with a sample of healthy Chinese Han adolescents. These findings promote the etiological understanding of adolescent aggression, highlighting the complex effect of stressful life events on aggression, and adding evidence supporting the relationship between the oxytocin system and aggressive behavior in adolescents.

Oxytocin and brain activity in humans: A systematic review and coordinate-based meta-analysis of functional MRI studies

Oxytocin (OXT) is a neuropeptide which has a critical role in human social behaviour and cognition. Research investigating the role of OXT on functional brain changes in humans has often used task paradigms that probe socioemotional processes. Preliminary evidence suggests a central role of the amygdala in the social cognitive effects of intranasal OXT (IN-OXT), however, inconsistencies in task-design and analysis methods have led to inconclusive findings regarding a cohesive model of the neural mechanisms underlying OXT's actions. The aim of this meta-analysis was to systematically investigate these findings. A systematic search of PubMed, PsycINFO, and Scopus databases was conducted for fMRI studies which compared IN-OXT to placebo in humans. First, we systematically reviewed functional magnetic resonance imaging (fMRI) studies of IN-OXT, including studies of healthy humans, those with clinical disorders, and studies examining resting-state fMRI (rsfMRI). Second, we employed a coordinate-based meta-analysis for task-based neuroimaging literature using activation likelihood estimation (ALE), whereby, coordinates were extracted from clusters with significant differences in IN-OXT versus placebo in healthy adults. Data were included for 39 fMRI studies that reported a total of 374 distinct foci. The meta-analysis identified task-related IN-OXT increases in activity within a cluster of the left superior temporal gyrus during tasks of emotion processing. These findings are important as they implicate regions beyond the amygdala in the neural effects of IN-OXT. The outcomes from this meta-analysis can guide a priori predictions for future OXT research, and provide an avenue for targeted treatment interventions.

Oxytocin Facilitates Empathic- and Self-embarrassment Ratings by Attenuating Amygdala and Anterior Insula Responses

The hypothalamic neuropeptide oxytocin has been reported to enhance emotional empathy in association with reduced amygdala activation, although to date studies have not investigated empathy for individuals expressing self-conscious, moral emotions which engage mentalizing as well as emotion processing networks. In the current randomized, double-blind placebo controlled functional MRI experiment in 70 male and female subjects we have therefore investigated the effects of intranasal oxytocin (40 IU) on behavioral and neural responses to embarrassment experienced by others or by self. Results showed that oxytocin significantly increased ratings of both empathic and self-embarrassment and concomitantly decreased skin conductance response, activation in the right amygdala and insula but not in the medial prefrontal cortex. The amygdala effects of oxytocin were associated with the magnitude of the skin conductance response and trait anxiety scores. Overall our results demonstrate that oxytocin increases ratings of self- and other embarrassment and that this is associated with reduced physiological arousal and activity in neural circuits involved in emotional arousal. The neural effects of oxytocin were more pronounced stronger in individuals with high trait anxiety suggesting that it may particularly reduce their anxiety in embarrassing situations.

Oxytocin differentially modulates specific dorsal and ventral striatal functional connections with frontal and cerebellar regions

Interactions between oxytocin and the basal ganglia are central in current overarching conceptualizations of its broad modulatory effects on behavior. Whereas evidence from animal models emphasizes the critical role of the ventral striatum in the behavioral effects of oxytocin, region-specific contributions of the basal ganglia have not been systematically explored in humans. The present study combined the randomized placebo-controlled administration of oxytocin versus placebo in healthy men (n = 144) with fMRI-based resting-state functional connectivity to determine the modulatory role of oxytocin on the major basal ganglia pathways. Oxytocin specifically increased connectivity between ventral striatal and pallidal nodes with upstream frontal regions, whereas it decreased the strengths of downstream pathways between the dorsal striatum and posterior cerebellum. These pathways have previously been implicated in salience, reward and behavioral flexibility, thus shaping goal-directed behavior. Given the importance of aberrant striatal intrinsic organization in autism, addiction and schizophrenia the present findings may suggest new mechanistic perspectives for the therapeutic potential of oxytocin in these disorders.

When Does Oxytocin Affect Human Memory Encoding? The Role of Social Context and Individual Attachment Style

The neuropeptide oxytocin plays an essential role in regulating social behavior and has been implicated in a variety of human cognitive processes in the social domain, including memory processes. The present study investigates the influence of oxytocin on human memory encoding, taking into account social context and personality, which have previously been neglected as moderators for how oxytocin affects memory encoding. To examine the role of social context of encoding, we employed an established experimental paradigm in which participants perform a word-categorization task in either a joint (social) or individual (non-social) setting. To investigate the role of socially relevant personality factors, participants' adult attachment style (AAS) was assessed. Previous research has identified attachment style as a potent moderator of oxytocin effects in the social-cognitive domain, but here we investigated for the first time its role in memory encoding. Participants were invited in pairs and received either placebo or oxytocin intranasally. Forty-five minutes later, they were instructed to react to different word categories within a list of successively presented words. This task was performed individually in the non-social condition and simultaneously with the partner in the social condition. After a 24-h delay, memory for all words was tested individually in a surprise recognition memory test. Oxytocin effects on memory accuracy depended on participants' AAS. Specifically, oxytocin positively affected memory for participants who scored low on attachment dependence (who find dependence on others uncomfortable), but negatively affected memory for high scorers (who are comfortable depending on others). Oxytocin effects were not moderated by social vs. non-social context at encoding, and we discuss reasons for this outcome. Regardless of encoding condition or personality, oxytocin led to more liberal responding in the recognition memory test, which was also reflected in significantly higher false alarm rates (FARs) and a trend towards higher hit rates (HRs) compared to placebo. Overall, our results are consistent with an interactionist view on oxytocin effects on human cognitive functioning. Future research should further examine how oxytocin affects response biases via previous encoding and the ways in which biological dispositions linked to attachment style affect the process of memory encoding.

Urinary oxytocin levels in relation to post-conflict affiliations in wild male chimpanzees (Pan troglodytes verus)

Many animals living in social groups have evolved behaviors to resolve conflicts between group members, behaviors thought crucial for maintaining stable group life. Several hypotheses, based mainly on observational data, aim to explain how post-conflict (PC) affiliations, such as reconciliation and consolation, resolve conflicts by restoring relationships and/or alleviating anxiety. To examine a potential endocrinological mechanism of PC affiliations, we used an experimental-like procedure to investigate whether the oxytocinergic system is activated during naturally observed reconciliations, receiving bystander PC affiliations and aggressions not followed by PC affiliations in wild male chimpanzees. We compared urinary oxytocin (uOT) levels after reconciliations, receiving bystander PC affiliations or aggressions without affiliations with two control conditions: affiliations without previous aggression and after time periods without social interactions. We furthermore tested the 'valuable relationship' hypothesis of reconciliation, as well as the influence of relationship quality between individuals engaged in each of the three behavioral conditions involving aggression on uOT levels. We found that the probability to reconcile a conflict increased with increasing relationship quality between opponents, thus our results support the 'valuable relationship' hypothesis. However, relationship quality did not influence uOT levels, while behavioral condition had a significant effect on uOT levels. uOT levels after reconciliations, receiving bystander PC affiliations and affiliations not related to conflicts were higher than after aggressions alone and time periods without social interactions. Overall, our results indicate that the oxytocinergic system is activated during affiliative interactions, whether occurring as reconciliation, bystander PC affiliation or affiliation alone. We conclude that the oxytocinergic system, in addition to building and maintaining social relationships, also takes part in repairing them.

Oxytocin Facilitates Approach Behavior to Positive Social Stimuli via Decreasing Anterior Insula Activity

BACKGROUND

The neuropeptide oxytocin can extensively modulate human social behavior and affective processing, and its effects can be interpreted in terms of mediating approach-avoidance motivational processes. However, little is known about how oxytocin mediates approach-avoidance behavior and particularly the underlying neural mechanisms.

METHODS

In a randomized, double-blind, between-subject design, the present pharmaco-fMRI study used an approach-avoidance paradigm to investigate oxytocin's effects on approach-avoidance behavior and associated neural mechanisms.

RESULTS

Results revealed that oxytocin generally decreased activity in the right striatum irrespective of response (approach/avoidance) and social context, suggesting an inhibitory effect on motivational representation during both appetitive approach and aversive avoidance. Importantly, while on the behavioral level oxytocin selectively enhanced accuracy when approaching social positive stimuli, on the neural level it decreased left ventral and right dorsal anterior insula activity in response to social vs nonsocial positive stimuli compared with the placebo treatment. The left ventral anterior insula activity was negatively correlated with the corresponding accuracy difference scores in the oxytocin but not in the placebo group.

CONCLUSION

Given the role of the ventral anterior insula in emotional processing and the dorsal anterior insula in salience processing, the oxytocin-induced suppression of activity in these regions may indicate that oxytocin is acting to reduce interference from hyper-activity in core regions of the emotional and salience networks when approaching salient positive social stimuli and thereby to promote social interaction. Thus, oxytocin may be of potential therapeutic benefit for psychiatric disorders exhibiting avoidance of social stimuli.

Oxytocin Enhancement of Emotional Empathy: Generalization Across Cultures and Effects on Amygdala Activity

Accumulating evidence suggests that the neuropeptide oxytocin (OXT) can enhance empathy although it is unclear which specific behavioral and neural aspects are influenced, and whether the effects are modulated by culture, sex, and trait autism. Based on previous findings in Caucasian men, we hypothesized that a single intranasal dose of OXT would specifically enhance emotional empathy (EE) via modulatory effects on the amygdala in an Asian (Chinese) population and explored the modulatory role of sex and trait autism on the effects. We first conducted a double-blind, randomized between-subject design experiment using a modified version of the multifaceted empathy task to determine whether OXT’s facilitation of EE can be replicated in Chinese men (n = 60). To further explore neural mechanisms behind and potential sex differences, functional MRI and skin conductance measures were acquired in an independent experiment incorporating men and women (n = 72). OXT enhanced EE across experiments and sex, an effect that was accompanied by reduced amygdala activity and increased skin conductance responses. On the network level OXT enhanced functional coupling of the right amygdala with the insula and posterior cingulate cortex for positive valence stimuli but attenuated coupling for negative valence stimuli. The effect of OXT on amygdala functional connectivity with the insula was modulated by trait autism. Overall, our findings provide further support for the role of OXT in facilitating EE and demonstrate that effects are independent of culture and sex and involve modulatory effects on the amygdala and its interactions with other key empathy regions.

Oxytocin strengthens the link between provocation and aggression among low anxiety people

Oxytocin (OT) not only modulates positive social interactions but also affects negative ones. Several studies have established a link between OT and aggression. However, they also resulted in an inconsistent picture and showed methodological issues. The current studies aimed to address these lacks and test the hypothesis that OT increases provocation-induced aggression in people low in anxiety. Therefore, two studies with 56 males (Study 1) as well as 40 females and 24 males (Study 2) were conducted. After responding to a trait anxiety questionnaire, participants self-administered OT or a placebo. Thereafter, provocation was manipulated by rejecting vs. accepting (Study 1) or insulting vs. accepting (Study 2) the participants by real human counterparts. Aggressive behavior was quantified by measuring how much hot sauce (Study 1) or unpleasant blasts of white noise (Study 2) participants delivered to their opponents, using two classic aggression paradigms. Both studies provided evidence that OT promotes aggression in response to provocation in low anxiety people which was not the case with no provocation or in high anxiety people. These findings confirm the idea that OT can be involved in the creation of aggressive behavior when accounting for situational and dispositional features.

The impact of sex as a biological variable in the search for novel antidepressants

A roadblock to successful treatment for anxiety and depression is the high proportion of individuals that do not respond to existing treatments. Different underlying neurobiological mechanisms may drive similar symptoms, so a more personalized approach to treatment could be more successful. There is increasing evidence that sex is an important biological variable modulating efficacy of antidepressants and anxiolytics. We review evidence for sex-specific effects of traditional monoamine based antidepressants and newer pharmaceuticals targeting kappa opioid receptors (KOR), oxytocin receptors (OTR), and N-methyl-D-aspartate receptors (ketamine). In some cases, similar behavioral effects are observed in both sexes while in other cases strong sex-specific effects are observed. Most intriguing are cases such as ketamine which has similar behavioral effects in males and females, perhaps through sex-specific neurobiological mechanisms. These results show how essential it is to include both males and females in both clinical and preclinical evaluations of novel antidepressants and anxiolytics.

Oxytocin effects on self-referential processing: behavioral and neuroimaging evidence

Oxytocin (OT) influences other-oriented mental processes (e.g. trust and empathy) and the underlying neural substrates. However, whether and how OT modulates self-oriented processes and the underlying brain activity remains unclear. Using a double-blind, placebo-controlled between-subjects design, we manipulated memory encoding and retrieval of trait adjectives related to the self, a friend and a celebrity in a self-referential task in male adults. Experiment 1 (N = 51) found that OT vs placebo treatments reduced response times during encoding self-related trait adjectives but increased recognition scores of self-related information during memory retrieval. Experiment 2 (N = 50) showed similar OT effects on response times during encoding self-related trait adjectives. Moreover, functional magnetic resonance imaging (fMRI) results revealed that OT vs placebo treatments decreased the activity in the medial prefrontal cortex (MPFC) involved in encoding of self-related trait adjectives and weakened the coupling between the MPFC activity and a cultural trait (i.e. interdependence). Experiment 3 (N = 52) revealed that OT vs placebo treatments increased the right superior frontal activity during memory retrieval of self-related information. The results provide behavioral and fMRI evidence for OT effects on self-referential processing and suggest distinct patterns of OT modulations of brain activities engaged in encoding and retrieval of self-related information.

Epigenetic regulation of the oxytocin receptor is associated with neural response during selective social attention

Aberrant attentional biases to social stimuli have been implicated in a number of disorders including autism and social anxiety disorder. Oxytocin, a naturally-occurring mammalian hormone and neuromodulator involved in regulating social behavior, has been proposed to impact basic biological systems that facilitate the detection of and orientation to social information. Here, we investigate a role for naturally-occurring variability in the endogenous oxytocinergic system in regulating neural response during attention to social information. Participants performed a selective social attention task while undergoing fMRI, provided a blood sample for epigenetic analysis, and completed self-report measures of social functioning. We find that a functional epigenetic modification to the oxytocin receptor, OXTR methylation, is associated with increased neural response within and decreased functional coupling between regions of the salience and attentional control networks during selective social attention. We also show that subclinical variability in autistic and social anxiety traits moderates this epigenetic regulation of neural response. These data offer a mechanistic explanation to a growing literature associating social behavior and disorder with epigenetic modification to OXTR by suggesting that OXTR methylation reflects a decrease in the extent to which social information automatically captures attention. We highlight the importance that treatment efficacy be considered in relation to individual differences in molecular makeup, and that future studies aimed at uncovering biomarkers of disorder carefully consider measurement at both the biological and phenotypic level.

A Systematic Review and Meta-analysis of the Effects of Meditation on Empathy, Compassion, and Prosocial Behaviors

Increased attention has focused on methods to increase empathy, compassion, and pro-social behavior. Meditation practices have traditionally been used to cultivate pro-social outcomes, and recently investigations have sought to evaluate their efficacy for these outcomes. We conducted a systematic review and meta-analysis of meditation for pro-social emotions and behavior. A literature search was conducted in PubMed, MEDLINE, PsycINFO, CINAHL, Embase, and Cochrane databases (inception-April 2016) using the search terms: mindfulness, meditation, mind-body therapies, tai chi, yoga, MBSR, MBCT, empathy, compassion, love, altruism, sympathy, or kindness. Randomized controlled trials in any population were included (26 studies with 1,714 subjects). Most were conducted among healthy adults (n=11) using compassion or loving kindness meditation (n=18) over 8-12weeks (n=12) in a group format (n=17). Most control groups were wait-list or no-treatment (n=15). Outcome measures included self-reported emotions (e.g., composite scores, validated measures) and observed behavioral outcomes (e.g., helping behavior in real-world and simulated settings). Many studies showed a low risk of bias. Results demonstrated small to medium effects of meditation on self-reported (SMD = .40, p < .001) and observable outcomes (SMD = .45, p < .001) and suggest psychosocial and neurophysiological mechanisms of action. Subgroup analyses also supported small to medium effects of meditation even when compared to active control groups. Clinicians and meditation teachers should be aware that meditation can improve positive pro-social emotions and behaviors.

A social neuroscience approach to conflict resolution: Dialogue intervention to Israeli and Palestinian youth impacts oxytocin and empathy

The rapid increase in terror-related activities, shift of battlefield into civilian locations, and participation of youth in acts of violence underscore the need to find novel frameworks for youth interventions. Building on the Israeli-Palestinian conflict and social neuroscience models we developed an eight-week dialogue group-intervention for youth growing up amidst intractable conflict. Eighty-eight Israeli-Jewish and Arab-Palestinian adolescents (16-18years) were randomly assigned to intervention or control groups. Before (T1) and after (T2) intervention, one-on-one conflict interaction with outgroup member were videotaped, oxytocin levels assayed, attitudes self-reported, and youth interviewed regarding national conflict. We tested the hypothesis that dialogue intervention would enhance empathic behavior and increase oxytocin levels following interaction with outgroup member. Intervention increased youth perspective-taking on national conflict. Oxytocin increased from T1 to T2 only for adolescents undergoing intervention who improved perspective taking in the process. Structural equation modelling charted three pathways to behavioral empathy toward outgroup member at T2; via endogenous oxytocin, empathic cognitions, and dialogue intervention; however, an alternative model without the intervention arm was non-significant. Our findings highlight the important role of empathy in programs for inter-group reconciliation and support evolutionary models on the precarious balance between the neurobiology of affiliation and the neurobiology of outgroup derogation.

Electrophysiological correlates of oxytocin-induced enhancement of social performance monitoring

Altered performance monitoring has been demonstrated after administration of different pharmacological compounds and in various clinical populations, such as excessive neurophysiological responses to mistakes in anxiety disorders. Here, a novel social pharmacological approach was applied to investigate whether oxytocin administration (24 IU) enhances performance monitoring for errors that have negative consequences for another individual, so-called social mistakes. Healthy male volunteers (N = 24) participated in a placebo-controlled crossover design. EEG measures were obtained while pairs of participants performed a speeded choice reaction-time task in an individual and social context. Following oxytocin administration, error-related negativity amplitudes were increased for social compared with individual mistakes. This increase was not found in the placebo condition. No effects of oxytocin were present in the individual context. The current study shows that oxytocin enhances performance monitoring specifically for social mistakes. This outcome is in line with a presumed role for oxytocin in salience attribution to social cues and underlines its context-dependency. Combining these processes may thus open up new research avenues and advance our understanding of individual differences in performance monitoring and oxytocin responses from a social neurocognitive, pharmacological and clinical perspective.

Intranasal Oxytocin Selectively Modulates Large-Scale Brain Networks in Humans

A growing body of evidence indicates that the neuropeptide oxytocin (OT) alters the neural correlates of socioemotional and salience processing. Yet the effects of OT over important large-scale networks involved in these processes, such as the default mode (DM), ventral attention (VA), and cingulo-opercular (CO) networks, remain unknown. Therefore, we conducted a placebo-controlled crossover study with intranasal 24 IU OT in 38 healthy male subjects using a resting-state functional magnetic resonance imaging paradigm to investigate its impact over these three networks candidates. To understand the underlying mechanisms of the neuropeptide, we compared the intranetwork connectivity for each network candidate and also the internetwork connectivity across all networks between both treatment conditions. Based on the relevance of interindividual factors for OT effects, we correlated individual network changes with behavioral performance in a decision-making task and with impulsivity scores. Our results show that OT mainly alters connectivity in the VA, on one side reducing the coupling to regions that typically form the nodes of DM, an introspective and self-referential network, and on the other side increasing the coupling to the edges of the CO, which is involved in salience processing. The results of the internetwork analyses confirmed the specificity of the OT effects. Indeed, we observed significant correlations with the erroneous performance during decision-making but not with the obtained impulsivity scores. Overall, our data support that the modulation of functional connectivity within the VA is a basic mechanism by which OT directs attentional resources from internal to external cues, preparing the brain for context-dependent salience processing.

How do hypothalamic nonapeptides shape youth's sociality? A systematic review on oxytocin, vasopressin and human socio-emotional development

The hypothalamic nonapeptides oxytocin and vasopressin are important modulators of socio-affective behaviours in a wide variety of animal species, including humans. Nevertheless, there is little research addressing their possible roles on socio-affective dimensions of human behaviour across development, during which considerable behavioural and physiological change occurs. Questions still remain about the extent to which findings from adults may directly apply to earlier phases of human development. In this article, we systematically summarize and discuss all existing studies investigating the developmental association of endogenous levels of hypothalamic neuropeptides oxytocin and vasopressin with human social behaviour or on its disruption in paediatric populations. Evidence is sparse insofar as there are still relatively few developmental studies and limited due to correlational research designs and unreliability of methods currently used for neuropeptide measurements in biological fluids. The findings to date generally converge with adult evidence, but also suggest that important differences between age stages may exist. Further studies focusing these differences may prove critical for informing drug development for socio-affective deficits in paediatric populations.

Aggression in Women: Behavior, Brain and Hormones

We review the literature on aggression in women with an emphasis on laboratory experimentation and hormonal and brain mechanisms. Women tend to engage in more indirect forms of aggression (e.g., spreading rumors) than other types of aggression. In laboratory studies, women are less aggressive than men, but provocation attenuates this difference. In the real world, women are just as likely to aggress against their romantic partner as men are, but men cause more serious physical and psychological harm. A very small minority of women are also sexually violent. Women are susceptible to alcohol-related aggression, but this type of aggression may be limited to women high in trait aggression. Fear of being harmed is a robust inhibitor of direct aggression in women. There are too few studies and most are underpowered to detect unique neural mechanisms associated with aggression in women. Testosterone shows the same small, positive relationship with aggression in women as in men. The role of cortisol is unclear, although some evidence suggests that women who are high in testosterone and low in cortisol show heightened aggression. Under some circumstances, oxytocin may increase aggression by enhancing reactivity to provocation and simultaneously lowering perceptions of danger that normally inhibit many women from retaliating. There is some evidence that high levels of estradiol and progesterone are associated with low levels of aggression. We highlight that more gender-specific theory-driven hypothesis testing is needed with larger samples of women and aggression paradigms relevant to women.

Oxytocin promotes face-sensitive neural responses to infant and adult faces in mothers

Research utilizing intranasal oxytocin (OT) administration has shown that OT may increase attention and sensitivity to social cues, such as faces. Given the pivotal role of OT in parental behaviors across mammals, the paucity of intranasal OT research investigating responses to social cues in parents and particularly mothers of young children is a critical limitation. In the current study, we recorded cortical event-related potentials (ERPs) to investigate whether intranasal OT affects the early neural responses to emotional faces in mothers of 1-year-old infants. Using a double-blind, within-subjects design, mothers (n = 38) were administered intranasal OT and placebo on separate sessions and presented with happy and sad infant and adult faces while ERP components reflecting face-sensitive brain activation and attention allocation were measured. We hypothesized that ERP responses to faces would be larger in the OT condition and that the effects of OT on ERP responses would be more pronounced for infant faces. The amplitudes of the face-sensitive N170 ERP component were larger in the OT condition to infant and adult faces, but no clear support was found for the hypothesis that the responses to infant faces would be more susceptible to OT effects than the responses to adult faces. The attention-sensitive late positive potential (LPP) component was not modulated by intranasal substance condition. The results are in line with the view that OT acts to enhance the perceptual salience of social and emotional stimuli. Demonstrating such effects in mothers of young children encourages further investigation of the potential of intranasal OT to affect the perception of social cues relevant for parent-child interaction.

The role of oxytocin in implicit personal space regulation: An fMRI study

Personal space, defined as the distance individuals choose to maintain between themselves and others, is an indicator of affiliation and closeness. Most paradigms that measure personal space preferences involve explicit choice and therefore fail to examine the implicit aspects of such preferences. In the current study, we sought to investigate an implicit form of interpersonal space that is more closely related to real-life situations involving affiliation. We studied the effects of oxytocin (OT) on neural networks that involve affiliation and tested the impact on personal space preferences. In a double-blind placebo-controlled study, we asked participants to choose between two rooms that differed only in the distances between two stimuli. The stimuli were either social stimuli (two chairs) or non-social stimuli (table and plant). The behavioral results showed that OT caused participants to choose a closer space in social blocks but did not affect their choices in non-social blocks. Imaging results revealed an interaction between stimulus and treatment (OT/PL) in the dorsal striatum, an area that is related to approach motivation and is part of the reward circuitry. Specifically, OT increased activity in the dorsal striatum in the social blocks and decreased this activity in the non-social blocks. The results of the study strengthen the social salience theory regarding OT, indicating that OT does not uniformly affect all social responses and that context has a determining impact on our behavior.

Impact of intranasal oxytocin on interoceptive accuracy in alcohol users: an attentional mechanism?

Interoception, i.e. the perception and appraisal of internal bodily signals, is related to the phenomenon of craving, and is reportedly disrupted in alcohol use disorders. The hormone oxytocin influences afferent transmission of bodily signals and, through its potential modulation of craving, is proposed as a possible treatment for alcohol use disorders. However, oxytocin's impact on interoception in alcohol users remains unknown. Healthy alcohol users (n = 32) attended two laboratory sessions to perform tests of interoceptive ability (heartbeat tracking: attending to internal signals and, heartbeat discrimination: integrating internal and external signals) after intranasal administration of oxytocin or placebo. Effects of interoceptive accuracy, oxytocin administration and alcohol intake, were tested using mixed-effects models. On the tracking task, oxytocin reduced interoceptive accuracy, but did not interact with alcohol consumption. On the discrimination task, we found an interaction between oxytocin administration and alcohol intake: Oxytocin, compared with placebo, increased interoceptive accuracy in heavy drinkers, but not in light social drinkers. Our study does not suggest a pure interoceptive impairment in alcohol users but instead potentially highlights reduced flexibility of internal and external attentional resource allocation. Importantly, this impairment seems to be mitigated by oxytocin. This attentional hypothesis needs to be explicitly tested in future research.

Maternal immune and affiliative biomarkers and sensitive parenting mediate the effects of chronic early trauma on child anxiety

BACKGROUND

Chronic early trauma alters children's stress reactivity and increases the prevalence of anxiety disorders; yet the neuroendocrine and immune mechanisms underpinning this effect are not fully clear. Animal studies indicate that the mother's physiology and behavior mediate offspring stress in a system-specific manner, but few studies tested this external-regulatory maternal role in human children exposed to chronic stress.

METHODS

We followed a unique cohort of children exposed to continuous wartime trauma (N = 177; exposed; N = 101, controls; N = 76). At 10 years, maternal and child's salivary immunoglobulin A (s-IgA) and oxytocin (OT), biomarkers of the immune and affiliation systems, were assayed, maternal and child relational behaviors observed, mother and child underwent psychiatric diagnosis, and child anxiety symptoms assessed.

RESULTS

War-exposed mothers had higher s-IgA, lower OT, more anxiety symptoms, and their parenting was characterized by reduced sensitivity. Exposed children showed higher s-IgA, more anxiety disorders and post traumatic stress disorder, and more anxiety symptoms. Path analysis model defined three pathways by which maternal physiology and behavior impacted child anxiety; (a) increasing maternal s-IgA, which led to increased child s-IgA, augmenting child anxiety; (b) reducing maternal OT, which linked with diminished child OT and social repertoire; and (c) increasing maternal anxiety, which directly impacted child anxiety.

CONCLUSIONS

Our findings, the first to measure immune and affiliation biomarkers in mothers and children, detail their unique and joint effects on children's anxiety in response to stress; highlight the relations between chronic stress, immune activation, and anxiety in children; and describe how processes of biobehavioral synchrony shape children's long-term adaptation.

To mirror or not to mirror upon mutual gaze, oxytocin can pave the way: A cross-over randomized placebo-controlled trial

The eyes constitute a highly salient cue to communicate social intent. Previous research showed that direct eye contact between two individuals can readily evoke an increased propensity to 'mirror' other peoples' actions. Considering the implicated role of the prosocial neuropeptide oxytocin (OXT) in enhancing the saliency of social cues and modulating approach/avoidance motivational tendencies, the current study adopted the non-invasive brain stimulation technique transcranial magnetic stimulation (TMS) to explore whether a single dose of intranasal OXT (24 IU) modulated (enhanced) a person's propensity to show heightened mirroring or motor resonance upon salient social cues, such as eye contact. The study involved a double-blind, placebo-controlled, cross-over trial with twenty-seven healthy adult men (19-32 y). By applying single-pulse TMS over the primary motor cortex during movement observation, it was shown that motor resonance was significantly higher when movement observation was accompanied by direct, compared to averted gaze, but that a single dose of OXT did not uniformly enhance this effect. Significant moderations of the treatment effect were noted however, indicating that participants with high self-reports of attachment avoidance displayed a stronger OXT-treatment effect (enhancement of motor resonance upon direct eye contact), compared to participants with low attachment avoidance. Particularly, while participants with high attachment avoidance initially displayed a reduced propensity to increase their motor resonance upon direct eye contact, a single dose of OXT was able to promote an otherwise avoidant individual's propensity to engage in motor resonance upon a salient social cue such as eye contact.

Maltreatment, the Oxytocin Receptor Gene, and Conduct Problems Among Male and Female Teenagers

The oxytocin receptor gene (OXTR) influences human behavior. The G allele of OXTR rs53576 has been associated with both prosocial and maladaptive behaviors but few studies have taken account of environmental factors. The present study determined whether the association of childhood maltreatment with conduct problems was modified by OXTR rs53576 genotypes. In a general population sample of 1591 teenagers, conduct problems as well as maltreatment were measured by self-report. DNA was extracted from saliva samples. In males, there was a significant positive association between maltreatment and conduct problems independent of the genotype. In females, among G allele carriers, the level of conduct problems was significantly higher among those who had been maltreated as compared to those not maltreated. By contrast, among female AA carriers, conduct problems did not vary between those who were, and who were not, maltreated. The results indicate that OXTR rs53576 plays a role in antisocial behavior in females such that the G allele confers vulnerability for antisocial behavior if they experience maltreatment, whereas the A allele has a protective effect.

Endogenous Oxytocin Release Eliminates In-Group Bias in Monetary Transfers With Perspective-Taking

Oxytocin (OT) has been shown to facilitate trust, empathy and other prosocial behaviors. At the same time, there is evidence that exogenous OT infusion may not result in prosocial behaviors in all contexts, increasing in-group biases in a number of studies. The current investigation seeks to resolve this inconsistency by examining if endogenous OT release is associated with in-group bias. We studied a large group of participants (N = 399) in existing groups and randomly formed groups. Participants provided two blood samples to measure the change in OT after a group salience task and then made computer-mediated monetary transfer decisions to in-group and out-group members. Our results show that participants with an increase in endogenous OT showed no bias in monetary offers in the ultimatum game (UG) to out-group members compared to in-groups. There was also no bias in accepting UG offers, though in-group bias persisted for a unilateral monetary transfer. Our analysis shows that the strength of identification with one's group diminished the effects that an increase in OT had on reducing bias, but bias only recurred when group identification reached 87% of its maximum value. Our results indicate that the endogenous OT system appears to reduce in-group bias in some contexts, particularly those that require perspective-taking.

Intranasal oxytocin does not reduce age-related difficulties in social cognition

Oxytocin is a neuropeptide that plays a key role in social processing and there are several studies suggesting that intranasally administered oxytocin may enhance social cognitive abilities and visual attention in healthy and clinical groups. However, there are very few studies to date that have investigated the potential benefits of intranasal oxytocin (iOT) on older adults' social cognitive abilities. This is a surprising omission, because relative to their younger counterparts, older adults also exhibit a range of social cognitive difficulties and also show differences in the way they visually attend to social information. Therefore, we tested the effect of iOT (24 IU) versus a placebo spray on 59 older and 61 younger adults' social cognitive abilities and visual attention using a double-blind placebo-controlled within-groups design. While iOT provided no overall age-related benefit on social cognitive abilities, the key finding to emerge was that iOT improved ToM ability in both age-groups when the task had minimal contextual information, but not when the task had enriched contextual information. Interestingly, iOT had gender specific effects during a ToM task with minimal context. For males in both age-groups, iOT reduced gazing to the social aspects of the scenes (i.e., faces & bodies), and for females, iOT eliminated age differences in gaze patterns that were observed in the placebo condition. These effects on eye-gaze were not observed in a very similar ToM task that included more enriched contextual information. Overall, these findings highlight the interactive nature of iOT with task related factors (e.g., context), and are discussed in relation to the social salience hypothesis of oxytocin.

Augmenting Prolonged Exposure therapy for PTSD with intranasal oxytocin: A randomized, placebo-controlled pilot trial

Posttraumatic stress disorder (PTSD) is a chronic, debilitating condition for which Prolonged Exposure (PE) therapy is highly efficacious. However, for some individuals, premature dropout and residual PTSD symptoms remain obstacles. The neuropeptide oxytocin is a promising candidate to enhance PE due to its ability to enhance 1) prosocial cognition and behavior, which are theorized to promote positive working alliance, and 2) extinction learning, which is the central mechanism of action underlying successful PE treatment. Despite a robust theoretical rationale, no studies to date have combined evidence-based psychotherapy for PTSD with oxytocin. This randomized, placebo-controlled, double-blind pilot trial examined the feasibility, safety, and preliminary efficacy of augmenting PE with oxytocin. Participants were 17 individuals with diverse index traumas. Participants self-administered intranasal oxytocin (40 IU) or matching placebo 45 min prior to each weekly PE therapy session. One adverse event occurred in the placebo group and three individuals dropped out (17.6%; 2 oxytocin group and 1 placebo group). The oxytocin group demonstrated lower PTSD and depression symptoms during PE, and had higher working alliance scores, although these differences did not reach statistical significance. Although preliminary, the findings support the feasibility of oxytocin combined with PE. Adequately powered studies are necessary to determine whether oxytocin enhances PE treatment outcomes and to examine potential mechanisms, such as accelerating extinction learning, enhancing early response, and preventing premature dropout. NCT03238924.

Intranasal oxytocin reduces heart rate variability during a mental arithmetic task: A randomised, double-blind, placebo-controlled cross-over study

Heart rate variability (HRV) refers to variation in the interval between successive heart beats. Low HRV is an indicator of potential autonomic nervous system dysfunction. People with chronic pain often display autonomic dysregulation, especially in the parasympathetic nervous system. The hormone oxytocin has been shown to increase HRV in non-clinical samples, but its potential impact on HRV in persons with chronic pain is unknown. This study investigated the impact of intranasal oxytocin on HRV in persons with chronic neck and shoulder pain. Participants included 24 individuals with chronic neck and shoulder pain lasting >12months and 24 age- and sex-matched pain-free controls. In a randomised double-blind, placebo-controlled, cross-over study, participants self-administered intranasal oxytocin (24IU) in one session, and placebo in another, before HRV was recorded at rest and during a mental arithmetic task. Intranasal oxytocin did not influence HRV at rest. However, compared to placebo, intranasal oxytocin elicited small decreases in low-frequency and high-frequency HRV in both groups during the mental arithmetic task. These results suggest that intranasal oxytocin may enhance the salience of the mental arithmetic task, leading to reduced engagement of the parasympathetic nervous system when completing the task. Further investigation and replication of these findings are required to improve our understanding of the effects of intranasal oxytocin on autonomic functioning both at rest and under cognitive stress.

Effects of oxytocin on cortisol reactivity and conflict resolution behaviors among couples with substance misuse

Social stress, particularly in the form of dyadic conflict, is a well-established correlate of substance use disorders (SUD). The neuropeptide oxytocin can enhance prosocial behavior and mitigate addictive behaviors. These effects may be, in part, a result of oxytocin's ability to attenuate hypothalamic-pituitary-adrenal (HPA) axis dysregulation. However, only one study to date has examined the effects of oxytocin on neuroendocrine reactivity or conflict resolution behavior among couples. Participants (N = 33 couples or 66 total participants) were heterosexual couples in which one or both partners endorsed substance misuse. Using a double-blind, placebo-controlled, repeated-measures design and an evidence-based behavioral coding system, we compared the impact of oxytocin (40 IU) vs. placebo on cortisol reactivity and conflict resolution behaviors. Among women, oxytocin attenuated cortisol response following the task. Oxytocin was also associated with increased Distress Maintaining Attributions and decreased Relationship Enhancing Attributions. Among men, oxytocin was associated with decreased Distress Maintaining Attributions, and both oxytocin and placebo yielded declines in Relationship Enhancing Attributions. The findings support emerging hypotheses that oxytocin may have differential effects in men and women, and indicate the need for future efforts to translate oxytocin's positive neurobiological effects into therapeutic behavioral changes.

Oxytocin Receptors in the Anteromedial Bed Nucleus of the Stria Terminalis Promote Stress-Induced Social Avoidance in Female California Mice

BACKGROUND

The neuropeptide oxytocin (OT) is a key regulator of social and emotional behaviors. The effects of OT are context dependent, and it has been proposed that OT increases the salience of both positive and negative social cues. Here we tested whether the bed nucleus of the stria terminalis (BNST) mediates anxiogenic effects of OT.

METHODS

First, we studied the effects of systemic administration of an OT receptor (OTR) antagonist L-368,899 on social behavior in male and female California mice exposed to social defeat. We examined the effect of L-368,899 on G protein activation and used early growth response factor 1 immunohistochemistry to identify potential sites of OTR action. Finally, we examined the effects of L-368,899 infused in the BNST on behavior.

RESULTS

A single dose of systemic L-368,899 increased social approach in stressed female mice and decreased social approach in male mice naïve to defeat. L-368,899 prevented OT activation of G proteins and did not activate G proteins in the absence of OT. Intranasal OT, which reduces social approach in female mice but not male mice, increased early growth response factor 1 immunoreactivity in the nucleus accumbens core and anteromedial BNST in female mice but not in male mice. Stressed female mice that received an infusion of L-368,899 into the anteromedial BNST but not the nucleus accumbens core increased social approach and decreased social vigilance responses.

CONCLUSIONS

Our results suggest that OTR activation in anteromedial BNST induces a vigilance response in which individuals avoid, yet attend to, unfamiliar social contexts. Our results suggest that OTR antagonists may have unappreciated therapeutic potential for stress-induced psychiatric disorders.

Oxytocin biases men to be more or less tolerant of others' dislike dependent upon their relationship status

The experience of being liked or disliked by others strongly influences our liking for and willingness to socialize with them. The neuropeptide oxytocin is involved in social bonding and can modify social preferences for others dependent upon their characteristics. However, it is unclear whether oxytocin affects individuals' reactions to social evaluations made by others (i.e., being liked or disliked) and if this is influenced by already having a secure partner bond (i.e., being single or in a relationship). We therefore performed a double-blind, between-subject, placebo controlled design study on 86 healthy males to investigate the effects of intranasal oxytocin (40IU) on the respective impact of being liked or disliked by others, and whether this was influenced by current relationship status.

RESULTS

showed while oxytocin decreased negative reactions to being disliked in single men it had the opposite effect on men in a relationship, and this occurred primarily when dislike was expressed by females rather than males. In contrast, for men in a relationship oxytocin enhanced mood and affiliation tendency following being liked independent of the gender of the feedback provider. Thus, oxytocin may make single men looking for a potential partner more positive socially even towards females who dislike them, but has the opposite effect in men in a relationship who are not looking for a partner. These results provide further support for the context-dependency of oxytocin effects' on social preferences, and thereby the social salience hypothesis-based explanation of its actions.

The role of trauma in the hormonal interplay of cortisol, testosterone, and oxytocin in adolescent aggression

Although numerous studies have examined the neuroendocrinology of aggression, the findings are mixed and focused on cortisol and testosterone. We argue that past findings remain inconclusive partly because the key roles of oxytocin and trauma have not been systematically integrated yet. Oxytocin is associated with social behavior and interacts with cortisol and testosterone, whereas trauma is a crucial risk factor of aggression that strongly affects hormonal activity. In this review, we investigate the role of trauma in the hormonal interplay of cortisol, testosterone, and oxytocin in aggression during adolescence. We first discuss how these hormones interact with each other and how trauma influences these interactions and then we propose a model that highlights the role of trauma in the hormonal interplay in aggression. We suggest that the timing of trauma has a distinct effect on hormonal activity and it should be integrated into any comprehensive model. Current trauma is linked to different levels of oxytocin, cortisol, testosterone, and testosterone/cortisol ratio than childhood trauma, but this distinction is also influenced by gender and type of aggression. We conclude that in order to better understand the neuroendocrinology of aggression, it is crucial to incorporate the investigation of oxytocin and trauma in future research.

Insular cortex mediates approach and avoidance responses to social affective stimuli

Social animals detect the affective states of conspecifics and utilize this information to orchestrate social interactions. In a social affective preference text in which experimental adult male rats could interact with either naive or stressed conspecifics, the experimental rats either approached or avoided the stressed conspecific, depending upon the age of the conspecific. Specifically, experimental rats approached stressed juveniles but avoided stressed adults. Inhibition of insular cortex, which is implicated in social cognition, and blockade of insular oxytocin receptors disrupted the social affective behaviors. Oxytocin application increased intrinsic excitability and synaptic efficacy in acute insular cortex slices, and insular oxytocin administration recapitulated the behaviors observed toward stressed conspecifics. Network analysis of c-Fos immunoreactivity in 29 regions identified functional connectivity between insular cortex, prefrontal cortex, amygdala and the social decision-making network. These results implicate insular cortex as a key component in the circuit underlying age-dependent social responses to stressed conspecifics.

Pupil-mimicry conditions trust in partners: moderation by oxytocin and group membership

Across species, oxytocin, an evolutionarily ancient neuropeptide, facilitates social communication by attuning individuals to conspecifics' social signals, fostering trust and bonding. The eyes have an important signalling function; and humans use their salient and communicative eyes to intentionally and unintentionally send social signals to others, by contracting the muscles around their eyes and pupils. In our earlier research, we observed that interaction partners with dilating pupils are trusted more than partners with constricting pupils. But over and beyond this effect, we found that the pupil sizes of partners synchronize and that when pupils synchronously dilate, trust is further boosted. Critically, this linkage between mimicry and trust was bound to interactions between ingroup members. The current study investigates whether these findings are modulated by oxytocin and sex of participant and partner. Using incentivized trust games with partners from ingroup and outgroup whose pupils dilated, remained static or constricted, this study replicates our earlier findings. It further reveals that (i) male participants withhold trust from partners with constricting pupils and extend trust to partners with dilating pupils, especially when given oxytocin rather than placebo; (ii) female participants trust partners with dilating pupils most, but this effect is blunted under oxytocin; (iii) under oxytocin rather than placebo, pupil dilation mimicry is weaker and pupil constriction mimicry stronger; and (iv) the link between pupil constriction mimicry and distrust observed under placebo disappears under oxytocin. We suggest that pupil-contingent trust is parochial and evolved in social species in and because of group life.

An integrated framework for the role of oxytocin in multistage social decision-making

Interest in the effects of oxytocin on social behavior has persisted even as an overarching theory describing these effects has remained largely elusive. Some of the earliest studies on the effects of oxytocin on social decision-making indicated that oxytocin might enhance prosocial actions directed toward others. This led to development of the prosocial hypothesis, which stipulates that oxytocin specifically enhances prosocial choices. However, further work indicated that oxytocin administration could elicit antisocial behaviors as well in certain social situations, highlighting the importance of context-dependent effects. At least two prominent hypotheses have been used to explain these seemingly contradictory findings. The social salience hypothesis indicates that the effects of oxytocin can be conceptualized as a general increase in the salience of social stimuli in the environment. Distinctly, the approach/withdrawal hypothesis stipulates that oxytocin enhances approach behaviors and decreases withdrawal behaviors. These phenomenologically motivated hypotheses regarding the effects of oxytocin on social behavior have created controversies in the field. In this review, we present a multistage framework of social decision-making designed to unify these disparate theories in a process common to all social decisions. We conceptualize this process as involving multiple distinct computational steps, including sensory input, sensory perception, valuation, decision formulation, and behavioral output. Iteratively, these steps generate social behaviors, and oxytocin could be acting on any of these steps to exert its effects. In support of this framework, we examine both behavioral and neural evidence across rodents, non-human primates, and humans, determining at what point in our multistage framework oxytocin could be eliciting its socially relevant effects. Finally, we postulate based on our framework that the prosocial, social salience, and approach/withdrawal hypotheses may not be mutually exclusive and could explain the influence of oxytocin on social behavior to different extents depending on context.

Oxytocin, social factors, and the expression of conditioned disgust (anticipatory nausea) in male rats

Disgust has been proposed to have evolved as a means to rid the body and mouth of noxious substances and toxins, as well as to motivate and facilitate avoidance of contact with disease-causing organisms and infectious materials. Nonemetic species, such as the rat, show distinctive facial expressions, including the gaping reaction, indicative of nausea-based disgust. These conditioned disgust responses can be used to model anticipatory nausea in humans, which is a learned response observed following chemotherapy treatment. As social factors play a role in the modulation and expression of conditioned disgust responses in rats, and the nonapeptide, oxytocin (OT), is involved in the modulation of social behavior, the present study examined the effects of an OT antagonist, L-368 899, on the development and expression of socially mediated conditioned disgust in male rats. When administered 10 min before testing in a distinct context (different from the original conditioning context), L-368 899 (5 mg/kg) significantly decreased gaping behavior in rats that were conditioned with a social partner. LiCl-treated rats administered L-368 899 before testing also showed decreased social initiations toward their social partner. These findings suggest that OT may play a role in the modulation and expression of socially mediated conditioned disgust in rats.

Oxytocin and Social Cognition

Oxytocin has been linked to many domains within the realm of "social cognition." For example, research has shown that oxytocin affects trusting behavior, cooperation, as well as the perception and processing of facial expressions. Furthermore, oxytocin increases empathy and seems to exert differential effects on in-group versus out-group preferences. However, there are some conflicting results that point towards a modulatory effect of oxytocin, depending on a variety of contextual and within-subject factors. Research about the underlying mechanisms (e.g., neural circuits and genetics) indicates that the modulation of amygdala activity by oxytocin is elementary for the understanding of social cognitive processes. As regards genetics, several variants of the oxytocin receptor gene (OXTR) have been extensively studied in relation to social cognition. Taken together, oxytocin is an important modulator of social cognitive processes, although substantially more research is needed in order to understand the complexity of oxytocinergic effects on social perception, cognition, and interpersonal behavior.