Oxytocin makes females, but not males, less forgiving following betrayal of trust

Oxytocin, but not vasopressin, decreases willingness to harm others by promoting moral emotions of guilt and shame

Prosocial and moral behaviors have overlapping neural systems and can both be affected in a number of psychiatric disorders, although whether they involve similar neurochemical systems is unclear. In the current registered randomized placebo-controlled trial on 180 adult male and female subjects, we investigated the effects of intranasal administration of oxytocin and vasopressin, which play key roles in influencing social behavior, on moral emotion ratings for situations involving harming others and on judgments of moral dilemmas where others are harmed for a greater good. Oxytocin, but not vasopressin, enhanced feelings of guilt and shame for intentional but not accidental harm and reduced endorsement of intentionally harming others to achieve a greater good. Neither peptide influenced arousal ratings for the scenarios. Effects of oxytocin on guilt and shame were strongest in individuals scoring lower on the personal distress subscale of trait empathy. Overall, findings demonstrate for the first time that oxytocin, but not vasopressin, promotes enhanced feelings of guilt and shame and unwillingness to harm others irrespective of the consequences. This may reflect associations between oxytocin and empathy and vasopressin with aggression and suggests that oxytocin may have greater therapeutic potential for disorders with atypical social and moral behavior.

Oxytocin in autism: Rethinking treatment and research through a neurodivergent perspective

This perspective piece addresses critical challenges in oxytocin-based interventions for autism, drawing on neurodivergent perspectives to highlight key issues in research relevance and inclusivity. Although oxytocin has been posited to modulate social and routinized behaviors in autistic individuals, empirical findings on its efficacy remain inconsistent. We argue that these behavioral targets may reflect neurotypical biases, often disregarding autistic individuals' perspectives, thereby limiting intervention acceptability and efficacy. Past research has frequently excluded marginalized autistic populations, including individuals with intellectual disabilities or gender-diverse identities, exacerbating generalizability issues. This piece advocates for a reorientation of research objectives in autism, proposing a shift from modifying core autistic behaviors towards enhancing quality of life through participatory research. By integrating autistic perspectives into study design and outcome selection, researchers move away from deficit-oriented frameworks and instead prioritize socially valid outcomes, such as reducing anxiety and improving adaptive functioning. Further, the perspective piece critiques the reliance on animal models, which often lack translational validity due to autism's complex social and communicative dimensions. In closing, we underscore the importance of inclusive, reproducible autism research practices that align with the lived experiences and priorities of autistic individuals. Embracing participatory research, alongside rigorous methodological adjustments, can foster advancements that effectively support the well-being of the autistic community.

Neuroimaging and behavioral evidence of sex-specific effects of oxytocin on human sociality

Although the social role of oxytocin came to light due to sex-specific interactions such as mother-offspring bonding, current understanding of sex differences in the effects of oxytocin on human sociality is limited because of the predominance of all-male samples. With the increasing inclusion of females in intranasal oxytocin research, it is now possible to explore such patterns. Neuroimaging studies reveal relatively consistent sex-differential effects of oxytocin on the activation of brain regions associated with processing social stimuli - particularly the amygdala. Findings from behavioral research are varied but suggest that oxytocin more often facilitates social cognition and positive social interactions in males, with context-dependent effects in each sex. We discuss potential biological and psychological mechanisms underlying the reported sex differences, and conclude with considerations for future research and clinical applications of oxytocin.

The impact of oxytocin on emotion recognition and trust: Does disordered eating moderate these relationships?

OBJECTIVES

The current study aimed to investigate the impact of oxytocin on emotion recognition, trust, body image, affect, and anxiety and whether eating disorder (ED) symptoms moderated any of these relationships.

METHOD

Participants (n = 149) were female university students, who were randomly allocated to receive in a double-blind nature, a single dose of oxytocin intranasal spray (n = 76) or a placebo (saline) intranasal spray (n = 73). Participants were asked to complete an experimental measure of emotion recognition and an investor task aimed to assess trust.

RESULTS

The oxytocin group exhibited better overall performance on the emotion recognition task (especially with recognising positive emotions), and a decline in state positive affect than the control group at post-intervention. However, these effects were not moderated by ED symptom severity, nor were effects found for state anxiety, negative affect, body image and recognising negative emotions in the emotion recognition task.

CONCLUSION

The current findings contribute to the growing literature on oxytocin, emotion recognition and positive affect and suggest that ED pathology does not moderate these relationships. Future research would benefit from examining the efficacy of an oxytocin intervention using a within-subjects, cross-over design, in those with sub-clinical and clinical EDs, as well as healthy controls.

Alarm or emotion? intranasal oxytocin helps determine information conveyed by dog barks for adult male human listeners

BACKGROUND

Barks play an important role in interspecific communication between dogs and humans, by allowing a reliable perception of the inner state of dogs for human listeners. However, there is growing concern in society regarding the nuisance that barking dogs cause to the surrounding inhabitants. We assumed that at least in part, this nuisance effect can be explained by particular communicative functions of dog barks. In this study we experimentally tested two separate hypotheses concerning how the content of dog barks could affect human listeners. According to the first hypothesis, barks that convey negative inner states, would especially cause stress in human listeners due to the process called interspecific empathy. Based on the second hypothesis, alarm-type dog barks cause particularly strong stress in the listener, by capitalizing on their specific acoustic makeup (high pitch, low tonality) that resembles to the parameters of a baby's cry. We tested 40 healthy, young adult males in a double-blind placebo controlled experiment, where participants received either intranasal oxytocin or placebo treatment. After an incubation period, they had to evaluate the (1) perceived emotions (happiness, fear and aggression), that specifically created dog bark sequences conveyed to them; and (2) score the annoyance level these dog barks elicited in them.

RESULTS

We found that oxytocin treatment had a sensitizing effect on the participants' reactions to negative valence emotions conveyed by dog barks, as they evaluated low fundamental frequency barks with higher aggression scores than the placebo-treated participants did. On the other hand, oxytocin treatment attenuated the annoyance that noisy (atonal) barks elicited from the participants.

CONCLUSIONS

Based on these results, we provide first-hand evidence that dog barks provide information to humans (which may also cause stress) in a dual way: through specific attention-grabbing functions and through emotional understanding.

Sniffing oxytocin: Nose to brain or nose to blood?

In recent years ample studies have reported that intranasal administration of the neuropeptide oxytocin can facilitate social motivation and cognition in healthy and clinical populations. However, it is still unclear how effects are mediated since intranasally administered oxytocin can both directly enter the brain (nose to brain) and increase peripheral vascular concentrations (nose to blood). The relative functional contributions of these routes are not established and have received insufficient attention in the field. The current study used vasoconstrictor pretreatment to prevent intranasal oxytocin (24 IU) from increasing peripheral concentrations and measured effects on both resting-state neural (electroencephalography) and physiological responses (electrocardiogram, electrogastrogram and skin conductance). Results demonstrated that intranasal oxytocin alone produced robust and widespread increases of delta-beta cross-frequency coupling (CFC) from 30 min post-treatment but did not influence peripheral physiological measures. As predicted, vasoconstrictor pretreatment greatly reduced the normal increase in peripheral oxytocin concentrations and, importantly, abolished the majority of intranasal oxytocin effects on delta-beta CFC. Furthermore, time-dependent positive correlations were found between increases in plasma oxytocin concentrations and corresponding increases in delta-beta CFC following oxytocin treatment alone. Our findings suggest a critical role of peripheral vasculature-mediated routes on neural effects of exogenous oxytocin administration with important translational implications for its use as an intervention in psychiatric disorders.

Towards better hypothesis tests in oxytocin research: Evaluating the validity of auxiliary assumptions

Various factors have been attributed to the inconsistent reproducibility of human oxytocin research in the cognitive and behavioral sciences. These factors include small sample sizes, a lack of pre-registered studies, and the absence of overarching theoretical frameworks that can account for oxytocin's effects over a broad range of contexts. While there have been efforts to remedy these issues, there has been very little systematic scrutiny of the role of auxiliary assumptions, which are claims that are not central for testing a hypothesis but nonetheless critical for testing theories. For instance, the hypothesis that oxytocin increases the salience of social cues is predicated on the assumption that intranasally administered oxytocin increases oxytocin levels in the brain. Without robust auxiliary assumptions, it is unclear whether a hypothesis testing failure is due to an incorrect hypothesis or poorly supported auxiliary assumptions. Consequently, poorly supported auxiliary assumptions can be blamed for hypothesis failure, thereby safeguarding theories from falsification. In this article, I will evaluate the body of evidence for key auxiliary assumptions in human behavioral oxytocin research in terms of theory, experimental design, and statistical inference, and highlight assumptions that require stronger evidence. Strong auxiliary assumptions will leave hypotheses vulnerable for falsification, which will improve hypothesis testing and consequently advance our understanding of oxytocin's role in cognition and behavior.

Oxytocin moderates the association between testosterone-cortisol ratio and trustworthiness: A randomized placebo-controlled study

Oxytocin has been proposed to enhance feelings of trust, however, these findings have been difficult to replicate. Environmental or hormonal factors might influence this association. We studied whether oxytocin moderates the association between the testosterone-cortisol ratio, which is associated with risk taking behavior and aggression, and trustworthiness, while controlling for the general level of trust. A randomized double-blind placebo-controlled study with 53 healthy males was performed in which 32IU oxytocin (n = 27) or placebo (n = 26) was administered intranasally. Participants subsequently played the Trust Game in which they were allocated to the role of trustee. In the third phase of the Trust Game, we found a positive association between the testosterone-cortisol-ratio and the proportion of the amount that is returned to the investor (P=<0.01). However, administration of oxytocin reduced reciprocity in those with a high testosterone-cortisol ratio after reciprocity restoration (a significant interaction effect between administration of oxytocin and the testosterone-cortisol ratio in the third phase of the Trust Game, P = 0.015). The third phase of the Trust Game represents the restoration of reciprocity and trustworthiness, after this is violated in the second phase. Therefore, our data suggest that oxytocin might hinder the restoration of trustworthiness and diminish risk-taking behavior when trust is violated, especially in those who are hormonally prone to risk-taking behavior by a high testosterone-cortisol ratio.

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Oxytocin (32IU) was administered intranasally to healthy young males in a double-blind placebo-controlled study.

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Testosterone-cortisol ratio was positively associated with trustworthiness during the Trust Game.

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Oxytocin significantly attenuated the association between testosterone-cortisol ratio and trustworthiness.

Intranasal oxytocin enhances the perception of ambiguous averted gaze in women but not in men

BACKGROUND

Perceiving accurately that others are looking away from us (averted gaze) is as important, for social interactions, as perceiving that others are looking at us (direct gaze). However, previous studies have revealed that when the deflection angle of averted gaze is small, individuals tend to falsely perceive it as direct gaze. Oxytocin (OXT) has been shown to increase orientation to the eye region. Therefore, a critical question is whether and how OXT would facilitate the perception of ambiguous averted gaze.

OBJECTIVES

The present study aimed to measure the effects of OXT on the performance of males and females in distinguishing ambiguous averted gaze from direct gaze of different emotional faces.

METHODS

In a double-blind placebo-controlled crossover experiment, 48 participants were presented successively two emotional faces with direct gaze (defined as 0, indicating the center of the eye) or averted gaze (defined as ±4, indicating the corner of the eye; +4 means that the iris moves 4 steps to the right; and -4 means that the iris moves 4 steps to the left) following intranasal oxytocin or placebo treatment and asked to make judgments on whether or not the two faces were the same in terms of identity. The interference effect of gaze direction was calculated by subtracting the mean accuracy and reaction time in the congruent gaze condition from those in the incongruent gaze condition. The logic of the measurement was if intranasal OXT would facilitate the detection of ambiguous averted gaze, we would observe a larger interference effect in the gaze incongruent condition compared with the gaze congruent condition, leading to longer RT or/and lower accuracy for identification judgment in the gaze incongruent condition.

RESULTS

While there were no OXT effects in accuracy, we found a significant interaction between treatment, sex, and gaze congruency in reaction times. That is, following OXT as compared to placebo, women displayed stronger interference of gaze direction, whereas in men no significant difference was observed. Besides, this interaction did not vary across different emotional expressions.

CONCLUSIONS

Our findings provide the first evidence for sex-dependent effects of OXT on the perception of ambiguous averted gaze. Given potential therapeutic applications of OXT to patients with developmental and psychiatric disorders, who are characterized as atypical in encoding gaze features, the findings suggest that rather different treatment outcomes could be anticipated in males and females.

Oxytocin-Trust Link in Oxytocin-Sensitive Participants and Those Without Autistic Traits

There have been numerous studies in which the biological role of oxytocin in trusting behavior has been investigated. However, a link between oxytocin and trust in humans was discovered only in one early study. We hypothesized that there is a large interindividual variation in oxytocin sensitivity, and that such variation is one reason for the doubt surrounding the role of oxytocin in trusting behavior. Here, in a double-blind, prospective, case-control study, we administered intranasal oxytocin to participants of trust and risk games. We measured salivary oxytocin concentration, relating it to the amount of money transferred among participants (a proxy for trust) and the autism-spectrum quotient (AQ). A one-sided Fisher’s exact test was performed to detect differences between the oxytocin and placebo groups in the proportions of investors who transferred the maximum amount of money. We discovered a tendency for participants who received oxytocin to transfer higher amounts of money to co-participants than those who received a placebo (P = 0.04). We also revealed a high degree of interindividual variation in salivary oxytocin concentrations after oxytocin administration. After stratifying the samples with respect to oxytocin sensitivity, oxytocin-sensitive participants in the oxytocin group also transferred higher amounts of money than those in the placebo group (P = 0.03), while such a tendency was not observed for oxytocin-insensitive participants (P = 0.34). Participants with lower AQ scores (less severe autistic traits) exhibited a greater tendency toward trusting behavior after oxytocin administration than did those with higher AQ scores (P = 0.02). A two-sample t-test that was performed to detect significant differences in the mean transfers between the oxytocin and placebo groups indicated no significant between-group difference in the mean transfers (P = 0.08). There are two possible interpretations of these results: First, there is no effect of oxytocin on trust in humans; second, the effects of oxytocin on trust in humans is person-dependent. However, the results should be interpreted with caution as the effect size was not larger than the minimal detectable effect size and the results were not statistically significant (P > 0.05) after Bonferroni corrections.

Neural and Molecular Contributions to Pathological Jealousy and a Potential Therapeutic Role for Intranasal Oxytocin

Romantic jealousy, especially in its pathological form, is a significant contributor to both domestic abuse, including partner sexual coercion and even murder, although relatively little research has been conducted on it. Both obsessive and delusional forms have been identified although only the latter is currently recognized as a pathological disorder. Studies in both clinical and healthy populations have identified altered fronto-striatal responsivity as being associated primarily with romantic jealousy and to date drug based treatments have targeted both dopaminergic and serotonergic systems. However, there is increasing interest in a potential role for the neuropeptide oxytocin, which can also modulate dopaminergic and serotonin systems in the brain and has been shown to altered in other psychotic conditions, such as schizophrenia and obsessive compulsive disorder. Recent studies in healthy populations have reported that when oxytocin is administered intranasally it can influence the brain to promote strengthening of romantic bonds and reduce romantic jealousy in both men and women evoked in either imagined or real contexts. These findings indicate a possible therapeutic use of intranasal oxytocin administration in pathological jealousy.

A meta-analysis of hormone administration effects on cooperative behaviours: Oxytocin, vasopressin, and testosterone

The hormones oxytocin, vasopressin, and testosterone have been implicated in cooperative behaviours and have attracted increasing research interest for their potential to regulate human cooperation in both healthy and clinical populations. However, the behavioural effects of the administration of these hormones remain to be verified. The current analysis included 41 studies involving 3,269 participants with a narrow age range. We examined the administration effects of these hormones on cooperative behaviour and the regulatory effects of individual characteristics, hormone interventions, and task structure and context. Results revealed a moderate positive effect size of oxytocin intranasal administration, a large negative effect size of vasopressin intranasal administration, and nonsignificant effects of testosterone administration on cooperative behaviours. Participants with mental dysfunctions were less sensitive to oxytocin and vasopressin administration. Oxytocin administration was effective in an in-group situation and for initial choices, corroborating a Tit-for-Tat strategy.

Oxytocin and vasopressin modulation of prisoner's dilemma strategies

BACKGROUND

The neuropeptides oxytocin and vasopressin have been repeatedly implicated in social decision making by enhancing social salience and, generally, cooperation. The iterated and sequential version of the prisoner's dilemma (PD) game is a social dilemma paradigm eliciting strategies of cooperation versus competition.

AIMS

We aimed to characterise the role of PD players' sex, game partner type (computer vs. human) and oxytocin or vasopressin inhalation on the player's strategy preference.

METHODS

Participants (153 men; 151 women) were randomised to intranasal 24 IU oxytocin, 20 IU vasopressin or placebo, double-blind, and played the PD. We examined main and interactive effects of sex, drug and partner type on strategy preference.

RESULTS

We found a pervasive preference for a tit-for-tat strategy (i.e. general sensitivity to the partner's choices) over unconditional cooperation, particularly when against a human rather than a computer partner. Oxytocin doubled this sensitivity in women (i.e. the preference for tit-for-tat over unconditional cooperation strategies) when playing against computers, which suggests a tendency to anthropomorphise them, and doubled women's unconditional cooperation preference when playing against humans. Vasopressin doubled sensitivity to the partner's previous choices (i.e. for tit-for-tat over unconditional cooperation) across sexes and partner types.

CONCLUSIONS

These findings suggest that women may be more sensitive to oxytocin's social effects of anthropomorphism of non-humans and of unconditional cooperation with humans, which may be consistent with evolutionary pressures for maternal care, and that vasopressin, irrespective of sex and partner type, may be generally sensitising humans to others' behaviour.

Competitiveness and individual characteristics: a double-blind placebo-controlled study using oxytocin

Oxytocin-enhanced prosocial behaviour depends on individual characteristics. This study investigated the relationship between oxytocin and competitiveness, which is another important social trait and predicts economic and social outcomes. In this double-blind, randomized, and placebo-controlled study of 192 male participants, we examined whether oxytocin moderates competitiveness and whether the effect of oxytocin on competitiveness is amplified in individuals with autistic traits. While our results show no relationship between oxytocin and competitiveness, we observed suggestive patterns: albeit not significantly, oxytocin reduced and enhanced competitiveness among participants without autistic traits and among their counterparts with autistic traits, respectively.

A registered replication study on oxytocin and trust

In an influential paper, Kosfeld et al. (2005) showed that intranasal administration of oxytocin (OT) increases the transfers made by investors in the trust game-suggesting that OT increases trust in strangers. Subsequent studies investigating the role of OT in the trust game found inconclusive effects on the trusting behaviour of investors but these studies deviated from the Kosfeld et al. study in an important way-they did not implement minimal social contact (MSC) between the investors and the trustees in the trust game. Here, we performed a large double-blind and placebo-controlled replication study of the effects of OT on trusting behaviour that yields a power of more than 95% and implements an MSC condition as well as a no-social-contact (NoC) condition. We find no effect of OT on trusting behaviour in the MSC condition. Exploratory post hoc analyses suggest that OT may increase trust in individuals with a low disposition to trust in the NoC condition, but this finding requires confirmation in future research. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 19 October 2018. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.11980368.

A Novel Role of CD38 and Oxytocin as Tandem Molecular Moderators of Human Social Behavior

Oxytocin is an important modulator of human affiliative behaviors, including social skills, human pair bonding, and friendship. CD38 will be discussed as an immune marker and then in more detail the mechanisms of CD38 on releasing brain oxytocin. Mention is made of the paralogue of oxytocin, vasopressin, that has often overlapping and complementary functions with oxytocin on social behavior. Curiously, vasopressin does not require CD38 to be released from the brain. This review discusses the social salience hypothesis of oxytocin action, a novel view of how this molecule influences much of human social behaviors often in contradictory ways. The oxytocinergic-vasopressinergic systems are crucial modulators of broad aspects of human personality. Of special interest are studies of these two hormones in trust related behavior observed using behavioral economic games. This review also covers the role of oxytocin in parenting and parental attachment. In conclusion, the effects of oxytocin on human behavior depend on the individual's social context and importantly as well, the individual's cultural milieu, viz. East and West. ACRONYMS: ACC = Anterior Cingulate ADP = Adenosine diphosphate AQ = Autism Quotient cADPR = Cyclic ADP-ribose CNS = Central nervous system DA = Dopamine eQTLC = Expression Quantitative Trait Loci LC-NE = Locus Coeruleus-Norepinephrine MRI = Magnetic Resonance Imaging OFC = Orbitofrontal cortices OXT = Oxytocin RAGE = Receptor for advanced glycation end-products SARM1 = Sterile Alpha and toll/interleukin-1 receptor motif-containing 1 TRPM2= Transient Receptor Potential Cation Channel Subfamily M Member 2 AVP = Vasopressin.

Oxytocin modulation of self-referential processing is partly replicable and sensitive to oxytocin receptor genotype

Intranasal oxytocin (OXT) has been associated with effects on diverse social-emotional domains in humans, however progress towards a therapeutic application of OXT in disorders with social-emotion impairments is currently hampered by poor replicability. Limited statistical power and individual differences in biological factors, such as oxytocin receptor (OXTR) genetics, may have contributed to these variable findings. To this end, employing a validated oxytocin-sensitive trait judgment paradigm, we present a pharmaco-genetic study aiming at (1) replicating previous findings suggesting that intranasal oxytocin (24 IU) reduces the self-referential bias in a large sample of n = 170 male subjects, (2) determining whether variations in common receptor polymorphisms (rs237887, rs2268491, rs2254298, rs53576, rs2268498) influence sensitivity to oxytocin's behavioral effects. We confirmed that in the whole sample oxytocin influenced self-other distinction in terms of reduced decision time. However, oxytocin only influenced decision time in rs53576 G carriers, whereas effects on subsequent memory performance were only found in rs2268498 TT homozygotes. In summary, the current study partially replicates our previous findings showing that oxytocin reduces the self-referential bias and suggests that sensitivity to its effects in this domain are receptor genotype dependent.

OXTR rs53576 polymorphism impacts interpersonal adaptability: Dispositional forgiveness as a mediator

Polymorphisms in the oxytocin receptor (OXTR) gene have been shown to be related to individual differences in social skills that are important for building and maintaining social relationships, such as the capability to efficiently process social information and regulate emotions. However, what remains unclear is the potential roles of OXTR polymorphisms in interpersonal adaptability, namely the ability to cope with the situational demands of interpersonal interactions. In this study, we examined the roles of OXTR rs53576 polymorphism in interpersonal adaptability, empathic perception, and dispositional forgiveness in a cohort of 573 college freshmen. The results indicated that the scores on interpersonal adaptability and dispositional forgiveness, apart from empathic perception, increased as functions of the number of G alleles of OXTR rs53576. Moreover, dispositional forgiveness, but not empathic perception, mediated the association between OXTR rs53576 and interpersonal adaptability. The findings highlight the influences of the OXTR gene on adaptive interpersonal interactions, especially when individuals face changing social situations.

Oxytocin Facilitates Social Learning by Promoting Conformity to Trusted Individuals

There is considerable interest in the role of the neuropeptide oxytocin in promoting social cohesion both in terms of promoting specific social bonds and also more generally for increasing our willingness to trust others and/or to conform to their opinions. These latter findings may also be important in the context of a modulatory role for oxytocin in improving the efficacy of behavioral therapy in psychiatric disorders. However, the original landmark studies claiming an important role for oxytocin in enhancing trust in others, primarily using economic game strategies, have been questioned by subsequent meta-analytic approaches or failure to reproduce findings in different contexts. On the other hand, a growing number of studies have consistently reported that oxytocin promotes conformity to the views of groups of in-group individuals. Most recently we have found that oxytocin can increase acceptance of social advice given by individual experts without influencing their perceived trustworthiness per se, but that increased conformity in this context is associated with how much an expert is initially trusted and liked. Oxytocin can also enhance the impact of information given by experts by facilitating expectancy and placebo effects. Here we therefore propose that a key role for oxytocin is not in facilitating social trust per se but in conforming to, and learning from, trusted individuals who are either in-group members and/or perceived experts. The implications of this for social learning and use of oxytocin as an adjunct to behavioral therapy in psychiatric disorders are discussed. Interpersonal trust within social groups is of key importance for social interactions, bonds, cooperation and learning and trust between different groups can also help ensure a stable and peaceful co-existence as well as mutually beneficial co-operation and trade. Trust is generally considered to be critical for co-operation and reciprocity in social and economic interactions but importantly trust also involves risk of potential injury if misplaced or broken and we have a natural aversion to taking such risks (Hardin, 2002; Ostrom and Walker, 2003). Indeed, an important factor influencing our trust behavior is that we are strongly motivated to avoid others betraying our trust (Bohnet and Zeckhauser, 2004; Bohnet et al., 2008). Trust can potentially be influenced by our assessment of the level of risk that trusting others might have and also by increased sensitivity to physical and/or other cues for detecting trustworthiness. It is therefore of great importance to identify both behavioral and physiological factors which can act to enhance trust, particularly in situations where individuals have impaired trust and therefore find it hard to interact socially with others and learn from them and/or to benefit optimally from cognitive and behavioral therapeutic strategies.

Effects of oxytocin on stress reactivity and craving in veterans with co-occurring PTSD and alcohol use disorder

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) are highly prevalent and commonly co-occur. The dual diagnosis of PTSD/AUD is associated with serious negative sequalae, and there are currently no effective pharmacological treatments for this comorbidity. Both PTSD and AUD are characterized by dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which helps modulate stress reactivity. Oxytocin, a neuropeptide that attenuates HPA axis dysregulation, may be beneficial for individuals with co-occurring PTSD/AUD. Thus, the current study examined the effects of intranasal oxytocin (40 IU) as compared with placebo on stress reactivity (e.g., cortisol) as well as subjective alcohol craving in response to a laboratory stress task (Trier Social Stress Task). Participants were 67 male U.S. military veterans with current PTSD and AUD (oxytocin n = 32, placebo n = 35; overall mean age = 49.06 years). Baseline cortisol levels were examined as a moderator of outcome. The findings revealed that oxytocin marginally attenuated cortisol reactivity in response to the stress task. Furthermore, oxytocin's effect was moderated by baseline cortisol level, such that oxytocin mitigated cortisol reactivity to a greater extent among participants with higher, as compared with lower, baseline cortisol. Oxytocin did not reduce craving. Although preliminary, the findings are the first to examine oxytocin in co-occurring PTSD/AUD. The findings from this study contribute to the growing literature examining the potential utility of oxytocin among individuals with psychiatric disorders, such as PTSD and substance use disorders. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The Role of Oxytocin in Antisocial Personality Disorders: A Systematic Review of the Literature

Background and aims: Antisocial personality disorder is an enduring mental disorder associated with significant disease burden and treatment difficulties. This is apparent within forensic populations. There is growing evidence to suggest that treatment with oxytocin could have some benefit in treating a range of psychiatric disorders. There are no reviews studying the use of oxytocin for patients with ASPD. We aim to present the first literature review on the use of oxytocin in patients with ASPD. Method: We searched relevant databases for original research on effect of oxytocin upon persons with a diagnosis of ASPD or healthy participants with symptoms seen in ASPD. Studies were included if they included healthy participants that evaluated the effect of oxytocin on symptoms relevant to ASPD, including empathy, inhibitory control, compliance, conformity, aggression, violence, and moral responsibility. Results: Thirty-six studies were included. There were a range of study designs, including randomized controlled trials, double blinded, single blinded, and unblinded controlled trials. The sample sizes in studies ranged from 20 to 259 participants. Studies looked at participants with a diagnosis of ASPD and participants with symptoms relevant to ASPD, including empathy, inhibitory control, compliance, conformity, aggression, violence, and moral responsibility. Oxytocin was found to demonstrate diversified effects, in most cases being associated with socially positive or non-criminogenic behaviors. However, some studies found opposite, and non-desirable, effects, e.g., an increase in violent inclinations to partners. The two studies looking at participants with ASPD had a number of limitations and had conflicting results on the impact that OT has on aggression in ASPD. Conclusions: This is the first systematic literature review exploring the potential use of oxytocin in managing ASPD and the symptoms of ASPD. It is apparent that there is a body of evidence addressing related symptoms in healthy individuals. There were diversified effects with oxytocin showing some benefits in promoting positive effects on symptoms of ASPD, but there were also studies showing non-desirable effects. It is difficult to draw any direct inferences from healthy control studies. Further high quality large sample studies are required to explore the effects of oxytocin in those with ASPD.

Where is the love? A double-blind, randomized study of the effects of intranasal oxytocin on stress regulation and aggression

Previous studies reveal that oxytocin (OT) encourages prosocial behavior in humans; however, animal studies and recent work in humans suggest that OT may also play a role in aggressive behavior and feelings. The present study investigated these competing predictions in the context of a competitive task among 85 healthy human participants (males and females). Using a randomized double-blind design, participants were assigned to an experimental (intranasal OT) or control (intranasal placebo) group. Hostility (Aggression Questionnaire) was measured at home (T1) and in the lab after intranasal administration (T2). Behavioral aggression was assessed post-intranasal administration. There was a significant difference between the OT and the placebo group on hostility scores (p = 0.03) and a significant time by group interaction for behavioral aggression (p < 0.05). Self-reported hostility was significantly higher at T2 compared to T1 (p < 0.001) among participants in the oxytocin group while no significant change was found in hostility among the placebo group. Behavioral aggression was slightly higher in the OT group (compared to the placebo group) directly after OT administration, however, the opposite relationship was found as the study period progressed. Both hostility and behavioral aggression findings were consistent across gender.

Neural substrates underlying the effects of oxytocin: a quantitative meta-analysis of pharmaco-imaging studies

The hypothalamic peptide oxytocin (OT) is crucial in social adaptation and used to treat emotional and social deficits. Here, we conducted a systematic, quantitative meta-analysis of functional-MRI studies intranasally administering OT (IN-OT) to uncover neural substrates underlying the IN-OT effects and to elucidate differential IN-OT effects between healthy and clinical populations. Meta-analyses were conducted on 66 IN-OT fMRI studies, stratified by psychopathology, valence and sex. IN-OT increased bilateral amygdala, caudate head, and superior temporal activity in healthy individuals and increased dorsal anterior cingulate activity in patients. Moreover, IN-OT decreased amygdala activity in both patients and healthy individuals but did so to a greater degree in patients than healthy individuals. The OT-increased amygdala activity was only found on the negative social and affective processes, whereas the OT-decreased amygdala activity was mainly contributed by contrasts on negative-valenced processes. IN-OT increased parahippocampal activity and decreased amygdala activity during negative socio-affective processing. During positive socio-affective processes, IN-OT increased caudate head activity. This study indicates convergent neural substrates and the underlying neuropsychological mechanisms for IN-OT effects on social and affective processes. The common and different effects of IN-OT on patients and healthy individuals and the modulation of OT effects by valence have critical implications.

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.

The (Null) Effect of Affective Touch on Betrayal Aversion, Altruism, and Risk Taking

Pleasant touch is thought to increase the release of oxytocin. Oxytocin, in turn, has been extensively studied with regards to its effects on trust and prosocial behavior, but results remain inconsistent. The purpose of this study was to investigate the effect of touch on economic decision making. Participants (n = 120) were stroked on their left arm using a soft brush (touch condition) or not at all (control condition; varied within subjects), while they performed a series of decision tasks assessing betrayal aversion (the Betrayal Aversion Elicitation Task), altruism (donating money to a charitable organization), and risk taking (the Balloon Analog Risk Task). We found no significant effect of touch on any of the outcome measures, neither within nor between subjects. Furthermore, effects were not moderated by gender or attachment. However, attachment avoidance had a significant effect on altruism in that those who were high in avoidance donated less money. Our findings contribute to the understanding of affective touch—and, by extension, oxytocin—in social behavior, and decision making by showing that touch does not directly influence performance in tasks involving risk and prosocial decisions. Specifically, our work casts further doubt on the validity of oxytocin research in humans.

Differential Effects of Oxytocin on Visual Perspective Taking for Men and Women

Although oxytocin (OXT) has been shown to lead to reduced self-orientation, no study to date has directly and effectively weakened the egocentric tendencies in perspective taking tasks for both men and women. In this double-blind, placebo-controlled, mixed design study we investigated the effects of OXT on men and women in visual perspective taking tasks. The results showed that OXT shortened the differences in response time between men and women in all experimental conditions. In addition, after OXT administration, the difference in reaction time between judging from one's own perspective and judging from others' perspectives decreased in female participants; however, this effect was not present in males. This may indicate that under OXT treatment, women have a higher tendency to overcome interference from their position and mindset when judging others' perspectives. However, OXT did not affect participants' accuracy, which is possibility because the used task was not suited to detect performance improvements caused by OXT. In summary, the above results may indicate that OXT could increase perspective-taking abilities through reducing self-bias and increasing the perception of others; furthermore, this trend mainly affected women rather than men.

Oxytocin conditions trait-based rule adherence

Rules, whether in the form of norms, taboos or laws, regulate and coordinate human life. Some rules, however, are arbitrary and adhering to them can be personally costly. Rigidly sticking to such rules can be considered maladaptive. Here, we test whether, at the neurobiological level, (mal)adaptive rule adherence is reduced by oxytocin—a hypothalamic neuropeptide that biases the biobehavioural approach-avoidance system. Participants (N = 139) self-administered oxytocin or placebo intranasally, and reported their need for structure and approach-avoidance sensitivity. Next, participants made binary decisions and were given an arbitrary rule that demanded to forgo financial benefits. Under oxytocin, participants violated the rule more often, especially when they had high need for structure and high approach sensitivity. Possibly, oxytocin dampens the need for a highly structured environment and enables individuals to flexibly trade-off internal desires against external restrictions. Implications for the treatment of clinical disorders marked by maladaptive rule adherence are discussed.

Psychophysiological effects of oxytocin on parent-child interactions: A literature review on oxytocin and parent-child interactions

Oxytocin (OT), often called the 'hormone of love' or 'hormone of attachment,' plays a fundamental role in the establishment and quality of parent-infant bonding. However, emerging evidence indicates that OT can also produce antisocial behavior. To clarify these effects, we review studies examining the role of endogenous and exogenous OT on several determinants of attachment: parental sensitivity, and bonding or synchrony in parent-child dyads. Contextual and individual factors moderating the effect of intranasal OT and its peripheral levels are also reviewed. Finally, potential therapeutic applications for OT and current limitations in human OT research are examined. This systematic literature review was based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, with two electronic databases and other bibliographic sources. We identified a total of 47 relevant studies for inclusion in our review. Most of the findings are in accordance with recent ideas that OT administration may increase parent-child prosocial interaction, showing that OT exerts beneficial effects on processes thought to promote bonding, sensitivity, and synchrony. However, we found that OT can induce antisocial behavior (e.g., anxiety) or adverse effects (modulation of maternal care recollections) that are moderated by different contextual (e.g., maltreatment level, presence of unfamiliar people) and individual (attachment style) factors. This review reinforces the importance of context- and individual-dependent factors, which must be taken into account when analyzing the psychophysiological effects of OT.

The oxytocinergic system modulates sadistic context-dependent empathy in humans

The oxytocinergic system is crucial for sociality and well-being and is associated with empathy. It is suggested that the oxytocinergic system exerts context- and person-dependent effects. We examined how sexual sadistic contexts influenced the effects of the oxytocinergic system on empathic-related behaviors and brain activity in healthy adults. Combining genetic neuroimaging, pharmacological techniques and a psychological paradigm of empathy, we recorded EEG neural responses in female OXTR rs53756 G/G and A/A carriers and measured subjective empathic ratings after intranasal administration of oxytocin/placebo in healthy male adults during the perception of painful facial expressions in sadistic/general social contexts. The results revealed that sadistic contexts modulate oxytocinergic effects on empathy at both behavioral and neural levels. The oxytocinergic system preferentially modulated empathic responses to sadistic contexts. These effects are moderated by individual’s trait empathy. Our combined genetic-pharmacological-imaging results provide a neurochemical mechanism for sadistic context-dependent effects of the oxytocinergic system on empathy.

How the brain codes intimacy: The neurobiological substrates of romantic touch

Humans belong to a minority of mammalian species that exhibit monogamous pair-bonds, thereby enabling biparental care of offspring. The high reward value of interpersonal closeness and touch in couples is a key proximate mechanism facilitating the maintenance of enduring romantic bonds. However, surprisingly, the neurobiological underpinnings mediating the unique experience of a romantic partner's touch remain unknown. In this randomized placebo (PLC)-controlled, between-group, pharmacofunctional magnetic resonance imaging (fMRI) study involving 192 healthy volunteers (96 heterosexual couples), we intranasally administered 24 IU of the hypothalamic peptide oxytocin (OXT) to either the man or the woman. Subsequently, we scanned the subjects while they assumed that they were being touched by their romantic partners or by an unfamiliar person of the opposite sex, although in reality an identical pattern of touch was always given by the same experimenter. Our results show that intranasal OXT compared to PLC selectively enhanced the subjective pleasantness of the partner's touch. Importantly, intranasal OXT selectively increased responses to partner touch in the nucleus accumbens (NAcc) and anterior cingulate cortex. Under OXT, NAcc activations to partner touch positively correlated with the subjects' evaluation of their relationship quality. Collectively, our results suggest that OXT may contribute to the maintenance of monogamous relationships in humans by concomitantly increasing the reward value of partner touch and diminishing the hedonic quality of stranger touch. Hum Brain Mapp 38:4525-4534, 2017. © 2017 Wiley Periodicals, Inc.

Oxytocin facilitation of acceptance of social advice is dependent upon the perceived trustworthiness of individual advisors

The neuropeptide oxytocin may increase social cohesion by making us more willing to trust others and/or to conform to their opinions. Here we investigated whether intranasal oxytocin can influence acceptance of advice given on solving everyday social problems by either individual expert (psychologist) or non-expert advisors with or without influencing their perceived likeability or trustworthiness. In a double-blind, between-subject, placebo-control design study in 160 male and female subjects, intranasal oxytocin (24IU) only significantly enhanced acceptance of advice given by female psychologists who were rated as the most trustworthy advisors. However, oxytocin itself did not alter either trustworthiness or likeability ratings. The oxytocin effect on acceptance of the female psychologist's advice was not maintained after a week, with subjects mainly reverting to their original solutions. These findings suggest that while oxytocin can transiently increase acceptance of advice from the most trustworthy individuals this is because it makes subjects more likely to conform to their opinions rather than enhancing their perceived trustworthiness or likeability. Thus in every day contexts oxytocin may primarily promote social cohesion by facilitating conformity towards the opinions of the most trusted individuals.

The Utility of Screening Colonoscopy During Kidney Transplant Evaluation

OBJECTIVES

Transplant centers often recommend, but not necessarily require, screening colonoscopies for people over 50 years of age in accordance with the US Preventative Services Task Force guidelines for the general population. We sought to identify risk factors affecting colonoscopy results in renal failure patients undergoing kidney transplant evaluation.

MATERIALS AND METHODS

We retrospectively examined patients undergoing kidney transplant evaluation from 2009 to 2012 (n = 469 patients). Comparisons were made between colonoscopy reports categorized as normal (no finding or hyperplastic polyp) or abnormal (adenomatous polyp or carcinoma).

RESULTS

Of 469 patients who met the study criteria, 303 (64.6%) had normal colonoscopies and 166 (35.4%) had abnormal colonoscopies. Logistic regression analysis showed that male sex (odds ratio = 2.09; 95% confidence interval, 1.37-3.20; P = .001) and increasing age (odds ratio = 1.04; 95% confidence interval, 1.01-1.08; P = .019) were more likely to correspond to abnormal findings. Those with dialysis vintage (length of time on dialysis) up to 3 years (odds ratio = 2.10; 95% confidence interval, 1.09-4.06; P = .027) and hypertension as the cause of renal failure (odds ratio = 1.79; 95% confidence interval, 1.05-2.87; P = .002) had more abnormal findings. No differences in length of evaluation, rate of being listed for transplant, and rate of transplant were shown.

CONCLUSIONS

The overall rate of adenomatous findings on colonoscopy was higher among patients with pretransplant end-stage renal disease than in the general population, as shown in other studies. Age, sex, dialysis vintage up to 3 years, and hypertensive renal failure were associated with adenomatous polyps of the colon in this study population. Because adenomatous polyp rates are high in patients with chronic kidney disease who are undergoing transplant evaluation and colonoscopic findings do not appear to delay transplant evaluations or listing rates, screening colonoscopies should be encouraged.

Prosocial Behavior and Depression: a Case for Developmental Gender Differences

Purpose of Review

Prosocial behavior and depression are related constructs that both increase during adolescence and display gender-specific effects. The current review surveys literature examining the association between depressive symptoms and prosociality, measured with behavioral economic paradigms, across development and proposes a theoretical model explaining a mechanism through which adolescent girls have higher risk for depression than boys.

Recent Findings

Relative to healthy controls, prosocial behavior is reduced in adults with major depressive disorder (MDD) but may be increased in adolescents with MDD. The relationship between non-clinical levels of depressive symptoms and prosocial behavior remains to be studied experimentally; however, self-reported prosocial behavior is negatively associated with depressive symptoms in non-clinical adolescents, which may suggest a shift in the relation of prosocial behavior and depressive symptoms across the non-clinical (i.e., negative) to clinical range (i.e., positive).

Summary

The effect of gender on these developmental and clinical status shifts has not been studied but could have important implications for understanding the emergence of higher rates of depression in girls than boys during adolescence. We propose that girls are at heightened risk for depression due to higher social-evaluative concern and other-oriented prosocial motivation that emphasize the needs of others over the self, leading to more altruistic prosocial behavior (despite personal cost) and a higher burden that enables depressive symptoms.

How Oxytocin Receptor (OXTR) Single Nucleotide Polymorphisms Act on Prosociality: The Mediation Role of Moral Evaluation

Prosociality is related to numerous positive outcomes, and mechanisms underlying individual differences in prosociality have been widely discussed. Recently, research has found converging evidence on the influence of the oxytocin receptor (OXTR) gene on prosociality. Meanwhile, moral reasoning, a key precursor for social behavior, has also been associated with variability in OXTR gene, thus the relationship between OXTR and prosociality is assumed to be mediated by moral evaluation. The current study examines the relationship in question, and includes gender as a potential moderator. Self-reported prosociality on Prosocial Tendencies Measure and evaluation on the moral acceptability of behaviors in stories from 790 Chinese adolescents (32.4% boys) were analyzed for the influence of their OXTR single nucleotide polymorphisms (SNPs). Results showed that SNP at site rs2254298 was indirectly associated with prosocial behaviors via moral evaluation of behaviors, and this effect was moderated by gender. Our findings suggest an indirect association between genetic variations in OXTR and prosociality through moral evaluation, indicating the potential pathway from genetic variability to prosociality through level of moral development. We also provide some evidence that the role of oxytocin system may to some extent depend on gender. These findings may promote our understanding of the genetic and biological roots of prosociality and morality.

Oxytocin biases men but not women to restore social connections with individuals who socially exclude them

We normally react to individuals who exclude us socially by either avoiding them or increasing our attempts to interact with them. The neuropeptide oxytocin can promote social bonds and reduce social conflict and we therefore investigated whether it facilitates more positive social responses towards individuals who exclude or include us. In a double-blind, placebo-controlled, between-subject design 77 healthy Chinese male and female participants received intranasal oxytocin (40 IU) or placebo before playing a modified virtual ball-tossing game with three fictitious partners who either showed exclusion, inclusion or neutral behavioral interactions with them. Results showed that both male and female subjects threw the ball more often to individuals who excluded rather than included them, although oxytocin did not alter this or awareness/feelings of exclusion or inclusion. However, when subjects returned a week later males, but not females, in the oxytocin group exhibited an increased liking for, and preference for playing again with, players who had previously excluded them. This oxytocin effect was positively associated with independent traits. Our findings suggest that in a collectivist culture oxytocin may promote the desire of males, but not females, with a stronger independent orientation to rebuild social connections with individuals who have previously excluded them.

Fear or greed? Oxytocin regulates inter-individual conflict by enhancing fear in men

People may choose non-cooperation in social dilemmas either out of fear (if others choose to defect) or out of greed (when others choose to cooperate). Previous studies have shown that exogenous oxytocin motivates a "tend and defend" pattern in inter-group conflict in which oxytocin stimulates in-group cooperation and out-group defense. Using a double-blind placebo-controlled design combined with a modified Prisoner's dilemma game (PDG), we examined the effect of oxytocin on social motivations in inter-individual conflict in men. Results showed that compared with the placebo group, oxytocin-exposed participants were less cooperative in general. Specifically, oxytocin amplified the effect of fear on defection but did not influence the effect of greed. Another non-social control study confirmed participants' decisions were sensitive to social factors. Our findings suggest that even when social group conflict is removed, oxytocin promotes distrust of strangers in "me and you" inter-individual conflict by elevating social fear in men.

Oxytocin and social context moderate social support seeking in women during negative memory recall

BACKGROUND

Oxytocin is theorized to promote social support seeking under stress- an alternate biobehavioural response to challenge known as the tend-and-befriend response. These effects may be context dependent, however, and no study has evaluated this effect in the presence and absence of social support. The aim of this study was to evaluate the effects of oxytocin on the experience of recalling emotional autobiographical memories in two contexts-with and without social contact with an experimenter.

METHOD

Sixty-three individuals (32 female) participated in this randomized, double-blind, placebo-controlled, and within-subject study.

RESULTS

During recall of negative memories in the absence of social contact, oxytocin decreased perceived emotional support relative to placebo F(1,62)=10.75, p=0.002. In this same context, women who were motivated to affiliate with the experimenter following oxytocin administration showed this effect in greater magnitude t(57)=-2.04, p=0.047, but showed the reverse effect (i.e. increased perceived support in response to oxytocin) when social contact with the experimenter was available t(57)=2.78, p=0.007. Male participants did not evidence this pattern.

CONCLUSION

These findings support the role of oxytocin in social support seeking in distressed women, and highlight the negative consequences of increasing oxytocin bioavailability in the absence of social support. Supportive relationships may be necessary to elicit the prosocial effects oxytocin.

The neuroendocrinology of love

Romantic love could be considered as a collection of activities associated with the acquisition and retention of emotions needed to survive and reproduce. These emotions change the individual's behavioural strategies in a way that will increase the likelihood of achieving these goals. Love may be defined as an emergent property of an ancient cocktail of neuropeptides and neurotransmitters. It appears that lust, attachment and attraction appear to be distinct but intertwined processes in the brain each mediated by its own neurotransmitters and circuits. These circuits feed on and reinforce each other. Sexual craving is mediated by testosterone and oestrogen and has the amygdala as an important centre. Attraction is mediated by hormones of stress and reward including dopamine, norepinephrine cortisol and the serotinergic system and has the nucleus accumbens the ventral tegmental area as key mediators.

Oxytocin blurs the self-other distinction during trait judgments and reduces medial prefrontal cortex responses

The neuropeptide oxytocin (OXT) may act either to increase or blur the distinction between self and other and thereby promote either more selfish or altruistic behaviors. To attempt to distinguish between these two possibilities we performed a double-blind, between-subject, placebo-controlled design study to investigate the effect of intranasal OXT on self and other (mother, classmate, or stranger) trait judgments in conjunction with functional magnetic resonance imaging. Results showed that OXT reduced response times for making both self and other judgments, but also reduced the accuracy of their subsequent recall, thereby abolishing the normal self-bias observed in this task. OXT also abolished the positive correlation between response and self-esteem scale scores seen in the PLC group, suggesting that its effects were strongest in individuals with higher levels of self-esteem. A whole-brain functional magnetic resonance imaging analysis revealed that OXT also reduced responses during both self and other trait judgments in the dorsal (dmPFC) and ventral (vmPFC) medial prefrontal cortex. A subsequent region of interest analysis revealed that behavioral performance and self-esteem scale scores were associated with dmPFC activation and its functional connectivity with the anterior cingulate and between the vmPFC and posterior cingulate. Thus overall, while OXT may improve speed of decision making in self -vs. other trait judgments it also blunts the normal bias towards remembering self-attributes and reduces mPFC responses and connectivity with other cortical midline regions involved in self-processing. This is consistent with the view that OXT can reduce self-centered behavior. Hum Brain Mapp 37:2512-2527, 2016. © 2016 Wiley Periodicals, Inc.

Oxytocin, Vasopressin, and the Motivational Forces that Drive Social Behaviors

The motivation to engage in social behaviors is influenced by past experience and internal state, but also depends on the behavior of other animals. Across species, the oxytocin (Oxt) and vasopressin (Avp) systems have consistently been linked to the modulation of motivated social behaviors. However, how they interact with other systems, such as the mesolimbic dopamine system, remains understudied. Further, while the neurobiological mechanisms that regulate prosocial/cooperative behaviors have been extensively examined, far less is understood about competitive behaviors, particularly in females. In this chapter, we highlight the specific contributions of Oxt and Avp to several cooperative and competitive behaviors and discuss their relevance to the concept of social motivation across species, including humans. Further, we discuss the implications for neuropsychiatric diseases and suggest future areas of investigation.

Hormonal contraceptives suppress oxytocin-induced brain reward responses to the partner's face

The hypothalamic peptide oxytocin (OXT) has been identified as a key modulator of pair-bonding in men, but its effects in women are still elusive. Moreover, there is substantial evidence that hormonal contraception (HC) influences partner preferences and sexual satisfaction, which constitute core domains of OXT function. We thus hypothesized that OXT effects on partner-related behavioral and neural responses could be significantly altered in women using HC. In this functional magnetic resonance imaging study involving 40 pair-bonded women, 21 of whom were using HC, we investigated whether a 24-IU nasal dose of OXT would modulate brain reward responses evoked by the romantic partner's face relative to the faces of familiar and unfamiliar people. Treatment with OXT increased the perceived attractiveness of the partner relative to other men, which was paralleled by elevated responses in reward-associated regions, including the nucleus accumbens. These effects of OXT were absent in women using HC. Our results confirm and extend previous findings in men that OXT interacts with the brain reward system to reinforce partner value representations, indicating a common OXT-dependent mechanism underlying partner attraction in both sexes. This mechanism may be disturbed in women using HC, suggesting that gonadal steroids could alter partner-specific OXT effects.

Does Oxytocin Increase Trust in Humans? A Critical Review of Research

Behavioral neuroscientists have shown that the neuropeptide oxytocin (OT) plays a key role in social attachment and affiliation in nonhuman mammals. Inspired by this initial research, many social scientists proceeded to examine the associations of OT with trust in humans over the past decade. To conduct this work, they have (a) examined the effects of exogenous OT increase caused by intranasal administration on trusting behavior, (b) correlated individual difference measures of OT plasma levels with measures of trust, and (c) searched for genetic polymorphisms of the OT receptor gene that might be associated with trust. We discuss the different methods used by OT behavioral researchers and review evidence that links OT to trust in humans. Unfortunately, the simplest promising finding associating intranasal OT with higher trust has not replicated well. Moreover, the plasma OT evidence is flawed by how OT is measured in peripheral bodily fluids. Finally, in recent large-sample studies, researchers failed to find consistent associations of specific OT-related genetic polymorphisms and trust. We conclude that the cumulative evidence does not provide robust convergent evidence that human trust is reliably associated with OT (or caused by it). We end with constructive ideas for improving the robustness and rigor of OT research.

Polymorphism of the Oxytocin Receptor Gene Modulates Behavioral and Attitudinal Trust among Men but Not Women

A relationship between the oxytocin receptor gene (OXTR) and behavioral and attitudinal trust has been suggested, but the nature of this relationship has not yet been established. We obtained behavioral trust data from 470 Japanese participants (242 women) aged 20–59 years, together with their levels of general trust and personality traits (NEO-FFI). Saliva buccal swabs were collected from 411 of these 470 participants and used for genotyping of OXTR rs53576. Our participants were found to have more AA alleles (40%) than GG alleles (12%). The GG men were more trusting and also rated higher on attitudinal trust than AA men, and this difference did not diminish when personality traits were controlled for. However, this pattern was not observed among women. In addition, controlling for attitudinal trust reduced the difference in behavioral trust among men to a non-significant level, but the difference in attitudinal trust remained significant when behavioral trust was controlled. These results indicate that the OXTR genotype affects attitudinal trust as part of an individual’s relatively stable disposition, and further affects behavioral trust through changes in attitudinal trust.

Failed Replication of Oxytocin Effects on Trust: The Envelope Task Case

The neurohormone Oxytocin (OT) has been one of the most studied peptides in behavioral sciences over the past two decades. Many studies have suggested that OT could increase trusting behaviors. A previous study, based on the "Envelope Task" paradigm, where trust is assessed by the degree of openness of an envelope containing participant's confidential information, showed that OT increases trusting behavior and reported one of the most powerful effects of OT on a behavioral variable. In this paper we present two failed replications of this effect, despite sufficient power to replicate the original large effect. The non-significant results of these two failed replications clearly exclude a large effect of OT on trust in this paradigm but are compatible with either a null effect of OT on trust, or a small effect, undetectable with small sample size (N = 95 and 61 in Study 1 and 2, respectively). Taken together, our results question the purported size of OT's effect on trust and emphasize the need for replications.

Oxytocin selectively facilitates learning with social feedback and increases activity and functional connectivity in emotional memory and reward processing regions

In male Caucasian subjects, learning is facilitated by receipt of social compared with non-social feedback, and the neuropeptide oxytocin (OXT) facilitates this effect. In this study, we have first shown a cultural difference in that male Chinese subjects actually perform significantly worse in the same reinforcement associated learning task with social (emotional faces) compared with non-social feedback. Nevertheless, in two independent double-blind placebo (PLC) controlled between-subject design experiments we found OXT still selectively facilitated learning with social feedback. Similar to Caucasian subjects this OXT effect was strongest with feedback using female rather than male faces. One experiment performed in conjunction with functional magnetic resonance imaging showed that during the response, but not feedback phase of the task, OXT selectively increased activity in the amygdala, hippocampus, parahippocampal gyrus and putamen during the social feedback condition, and functional connectivity between the amygdala and insula and caudate. Therefore, OXT may be increasing the salience and reward value of anticipated social feedback. In the PLC group, response times and state anxiety scores during social feedback were associated with signal changes in these same regions but not in the OXT group. OXT may therefore have also facilitated learning by reducing anxiety in the social feedback condition. Overall our results provide the first evidence for cultural differences in social facilitation of learning per se, but a similar selective enhancement of learning with social feedback under OXT. This effect of OXT may be associated with enhanced responses and functional connectivity in emotional memory and reward processing regions.

Opposing effects of oxytocin on moral judgment in males and females

Current perspectives on the evolutionary roots of human morality suggest it arose to incentivize social cooperation by promoting feelings of disgust toward selfish behavior, although the underlying neural mechanisms remain unclear. To investigate whether the ancient mammalian neuropeptide oxytocin (OXT) influences self-referential processing in the domains of emotion evaluation and moral decision making, we conducted a pharmaco-functional magnetic resonance imaging (fMRI) and a behavioral experiment involving 157 healthy women and men who were treated with either OXT (24 IU) or placebo (PLC) intranasally. Our results show that OXT facilitated cortical midline responses during self-processing of disgust and selectively promoted self-interest moral judgments in men. In contrast, in women OXT increased the reaction time difference between accepted and rejected moral dilemmas and led them to suppress their self-interest and respond more altruistically for the benefit of others. Taken together, these findings suggest an OXT-related sexual dimorphism in human moral behavior which evolved adaptively to optimize both protection and nurturing of offspring by promoting selfish behavior in men and altruistic behavior in women.

Oxytocin increases liking for a country's people and national flag but not for other cultural symbols or consumer products

The neuropeptide oxytocin enhances in-group favoritism and ethnocentrism in males. However, whether such effects also occur in women and extend to national symbols and companies/consumer products is unclear. In a between-subject, double-blind placebo controlled experiment we have investigated the effect of intranasal oxytocin on likeability and arousal ratings given by 51 adult Chinese males and females for pictures depicting people or national symbols/consumer products from both strong and weak in-groups (China and Taiwan) and corresponding out-groups (Japan and South Korea). To assess duration of treatment effects subjects were also re-tested after 1 week. Results showed that although oxytocin selectively increased the bias for overall liking for Chinese social stimuli and the national flag, it had no effect on the similar bias toward other Chinese cultural symbols, companies, and consumer products. This enhanced bias was maintained 1 week after treatment. No overall oxytocin effects were found for Taiwanese, Japanese, or South Korean pictures. Our findings show for the first time that oxytocin increases liking for a nation's society and flag in both men and women, but not that for other cultural symbols or companies/consumer products.