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

How does oxytocin modulate human behavior?

While the highly evolutionarily conserved hypothalamic neuropeptide, oxytocin (OT) can influence cognitive, emotional and social functions, and may have therapeutic potential in disorders with social dysfunction, it is still unclear how it acts. Here, we review the most established findings in both animal model and human studies regarding stimuli which evoke OT release, its primary functional effects and the mechanisms whereby exogenous administration influences brain and behavior. We also review progress on whether OT administration can improve social symptoms in autism spectrum disorder and schizophrenia and consider possible impediments to translational success. Importantly, we emphasize that OT acting via its extensive central or peripheral receptors primarily influences behavior indirectly through neuromodulatory interactions with classical transmitters and other peptides which themselves can independently influence behavior. We also emphasize that exogenous administration studies increasingly demonstrate peripheral effects of OT may be of greater importance than originally thought, especially involving the vagus. Overall, we propose a hierarchical model whereby OT's neuromodulatory actions influence behavior across interconnected functional domains and ultimately help to promote survival, security and sociability. Initially, OT potently facilitates attention to salient social and other important stimuli and additionally modulates cognitive, emotional and reward processing in a person- and context-dependent manner to promote interpersonal social understanding, attraction and bonds on the one hand and social group cohesion through increased conformity, altruistic punishment and moral emotions on the other. OT also increases co-operation and protection across both social domains. We hope this review and model will promote further research and help aid future translation success.

Oxytocin enhances the triangular association among behavior, resting-state, and task-state functional connectivity

Considerable advances in the role of oxytocin (OT) effect on behavior and the brain network have been made, but the effect of OT on the association between inter-individual differences in functional connectivity (FC) and behavior is elusive. Here, by using a face-perception task and multiple connectome-based predictive models, we aimed to (1) determine whether OT could enhance the association among behavioral performance, resting-state FC (rsFC), and task-state FC (tsFC) and (2) if so, explore the role of OT in enhancing this triangular association. We found that in the OT group, the prediction performance of using rsFC or tsFC to predict task behavior was higher than that of the PL group. Additionally, the correlation coefficient between rsFC and tsFC was substantially higher in the OT group than in the PL group. The strength of these associations could be partly explained by OT altering the brain's FCs related to social cognition and face perception in both the resting and task states, mainly in brain regions such as the limbic system, prefrontal cortex, temporal poles, and temporoparietal junction. Taken together, these results provide novel evidence and a corresponding mechanism for how neuropeptides cause increased associations among inter-individual differences across different levels (e.g., behavior and large-scale brain networks in both resting and task-state), and may inspire future research on the role of neuropeptides in the cross levels association of both clinical and nonclinical use.

Better safe than sorry: Oxytocin shifts the regulatory focus

Oxytocin (OT) is known to play a major role in social cognition and behavior. In this study, we aimed to investigate whether OT also affects the motivational system, specifically, the regulatory focus. Because OT weakens the self- and promotes the other-bias, we hypothesized that OT would decrease promotion focus and increase prevention focus. To test this, we conducted two experiments. In each, male participants intranasally administered OT or a placebo and assessed their regulatory focus using validated paradigms. Results revealed that OT led to an increase of prevention focus (Studies 1 and 2) and a slight but non-significant decrease of promotion focus (Study 2). Thus, participants under OT (vs. placebo) saw potential losses as more important, while they tended to devaluate potential gains. This was unrelated to the perceived likelihood of success. These findings indicate that OT might provide adaption to the social environment by pursuing a vigilant motivational strategy.

The role of oxytocin in modulating self-other distinction in human brain: a pharmacological fMRI study

Self-other distinction is crucial for human interaction. Although with conflicting results, studies have found that oxytocin (OT) sharpens the self-other perceptual boundary. However, little is known about the effect of OT on self-other perception, especially its neural basis. Moreover, it is unclear whether OT influences self-other discrimination when the other is a child or an adult. This double-blind, placebo-controlled study investigated the effect of OT on self-face perception at the behavioral and neural levels. For the stimuli, we morphed participants' faces and child or adult strangers' faces, resulting in 4 conditions. After treatment with either OT or placebo, participants reported whether a stimulus resembled themselves while being scanned using functional magnetic resonance imaging (fMRI). Behavioral results showed that people judged adult-morphed faces better than child-morphed faces. Moreover, fMRI results showed that the OT group exhibited increased activity in visual areas and the inferior frontal gyrus for self-faces. This difference was more pronounced in the adult-face condition. In multivariate fMRI and region of interest analyses, better performance in the OT group indicated that OT increased self-other distinction, especially for adult faces and in the left hemisphere. Our study shows a significant effect of OT on self-referential processes, proving the potential effect of OT on a left hemisphere self-network.

OXTR polymorphisms and parental bonding modulate alexithymia: The main effects and interaction

Alexithymia is a subclinical personality disorder characterized by difficulties in identifying and expressing one's own emotion. Individual differences in alexithymia are influenced by both genetic and environmental factors. However, the interplay between these factors and their influences on alexithymia are unclear. Considering that oxytocin plays important roles in emotion processing and that parental bonding influences the development of alexithymia, we explored the associations between OXTR polymorphisms and alexithymia and examined whether the potential associations are moderated by parental bonding. To this end, we genotyped the OXTR polymorphisms (rs53576 and rs1042778) and scored alexithymia and parental bonding with the Toronto Alexithymia Scale and the Parental Bonding Instrument. Results indicated that: (1) the characteristics of alexithymia were negatively associated with parental care and positively with parental overprotection; (2) the OXTR rs53576 was significantly associated with the characteristics of alexithymia, such that the AA genotype was associated with fewer difficulties in identifying feelings and describing feelings than the AG/GG genotypes; and (3) the OXTR rs1042778 interacted with parental care in alexithymia with the vantage sensitivity model: the GG genotype was related to less severity of alexithymia than the AG/GG genotypes only in individuals with higher parental care. Overall, these findings suggest that the OXTR is related to alexithymia and that the quality of parental care influences the relationship. However, considering that the evidence from this study is weak, more research is needed to understand the roles of OXTR in alexithymia.

The (un)learning of social functions and its significance for mental health

Social interactions are dynamic, context-dependent, and reciprocal events that influence prospective strategies and require constant practice and adaptation. This complexity of social interactions creates several research challenges. We propose a new framework encouraging future research to investigate not only individual differences in capacities relevant for social functioning and their underlying mechanisms, but also the flexibility to adapt or update one's social abilities. We suggest three key capacities relevant for social functioning: (1) social perception, (2) sharing emotions or empathizing, and (3) mentalizing. We elaborate on how adaptations in these capacities may be investigated on behavioral and neural levels. Research on these flexible adaptations of one's social behavior is needed to specify how humans actually "learn to be social". Learning to adapt implies plasticity of the relevant brain networks involved in the underlying social processes, indicating that social abilities are malleable for different contexts. To quantify such measures, researchers need to find ways to investigate learning through dynamic changes in adaptable social paradigms and examine several factors influencing social functioning within the three aformentioned social key capacities. This framework furthers insight concerning individual differences, provides a holistic approach to social functioning, and may improve interventions for ameliorating social abilities in patients.

Oxytocin receptor single nucleotide polymorphism predicts atony-related postpartum hemorrhage

BACKGROUND

Postpartum hemorrhage remains a key contributor to overall maternal morbidity in the United States. Current clinical assessment methods used to predict postpartum hemorrhage are unable to prospectively identify about 40% of hemorrhage cases. Oxytocin is a first-line pharmaceutical for preventing and treating postpartum hemorrhage, which acts through oxytocin receptors on uterine myocytes. Existing research indicates that oxytocin function is subject to variation, influenced in part by differences in the DNA sequence within the oxytocin receptor gene. One variant, rs53576, has been shown to be associated with variable responses to exogenous oxytocin when administered during psychological research studies. How this variant may influence myometrial oxytocin response in the setting of third stage labor has not been studied. We tested for differences in the frequency of the oxytocin receptor genotype at rs53576 in relationship to the severity of blood loss among a sample of individuals who experienced vaginal birth.

METHODS

A case-control prospective design was used to enroll 119 postpartum participants who underwent vaginal birth who were at least 37 weeks of gestation. Cases were defined by either a 1000 mL or greater blood loss or instances of heavier bleeding where parturients were given additional uterotonic treatment due to uterine atony. Controls were matched to cases on primiparity and labor induction status. Genotype was measured from a maternal blood sample obtained during the 2^nd postpartum month from 95 participants. Statistical analysis included bivariate tests and generalized linear and Poisson regression modeling.

RESULTS

The distribution of the genotype across the sample of 95 participants was 40% GG (n = 38), 50.5% AG (n = 48) and 9.5% AA (n = 9). Blood loss of 1000 mL or greater occurred at a rate of 7.9% for GG, 12.5% for AG and 55.6% for AA participants (p = 0.005). Multivariable models demonstrated A-carriers (versus GG) had 275.2 mL higher blood loss (95% CI 96.9-453.4, p < 0.01) controlling for parity, intrapartum oxytocin, self-reported ancestry, active management of third stage or genital tract lacerations. Furthermore, A-carrier individuals had a 79% higher risk for needing at least one second-line treatment (RR = 1.79, 95% CI = 1.08-2.95) controlling for covariates. Interaction models revealed that A-carriers who required no oxytocin for labor stimulation experienced 371.4 mL greater blood loss (95% CI 196.6-546.2 mL).

CONCLUSIONS

We provide evidence of a risk allele in the oxytocin receptor gene that may be involved in the development of postpartum hemorrhage among participants undergoing vaginal birth, particularly among those with fewer risk factors. The findings, if reproducible, could be useful in studying pharmacogenomic strategies for predicting, preventing or treating postpartum hemorrhage.

Depressive symptoms and social context modulate oxytocin's effect on negative memory recall

Oxytocin promotes social affiliation across various species, in part by altering social cognition to facilitate approach behaviour. However, the effects of intranasal oxytocin on human social cognition are mixed, perhaps because its effects are context dependent and subject to inter-individual differences. Few studies have included explicit manipulations of social context to test this supposition. We examined oxytocin's effects on autobiographical memory recall in two contexts, with and without social contact, and evaluated whether these effects were moderated by depressive symptoms. Two non-clinical samples (Study 1, n = 48; Study 2, n = 63) completed randomised, placebo-controlled, within-subject experiments. We assessed autobiographical memory recall across two sessions (intranasal oxytocin or placebo) and two contexts (memories elicited by an experimenter or by computer). Overall, intranasal oxytocin increased ratings of the vividness of recalled memories during the social context only. Individuals with elevated depressive symptoms also recalled memories that were more negative following oxytocin relative to placebo only in the non-social context across the two studies. Findings highlight the negative consequences of increasing oxytocin bioavailability in vulnerable persons in the absence of social contact. Contextual factors such as social isolation among depressed populations may complicate the clinical use of oxytocin.

Advances in the field of intranasal oxytocin research: lessons learned and future directions for clinical research

Reports on the modulatory role of the neuropeptide oxytocin on social cognition and behavior have steadily increased over the last two decades, stimulating considerable interest in its psychiatric application. Basic and clinical research in humans primarily employs intranasal application protocols. This approach assumes that intranasal administration increases oxytocin levels in the central nervous system via a direct nose-to-brain route, which in turn acts upon centrally-located oxytocin receptors to exert its behavioral effects. However, debates have emerged on whether intranasally administered oxytocin enters the brain via the nose-to-brain route and whether this route leads to functionally relevant increases in central oxytocin levels. In this review we outline recent advances from human and animal research that provide converging evidence for functionally relevant effects of the intranasal oxytocin administration route, suggesting that direct nose-to-brain delivery underlies the behavioral effects of oxytocin on social cognition and behavior. Moreover, advances in previously debated methodological issues, such as pre-registration, reproducibility, statistical power, interpretation of non-significant results, dosage, and sex differences are discussed and integrated with suggestions for the next steps in translating intranasal oxytocin into psychiatric applications.

Social Cognition in a Research Domain Criteria Perspective: A Bridge Between Schizophrenia and Autism Spectra Disorders

Schizophrenia and autism spectra disorders are currently conceptualized as distinct clinical categories. However, the relationship between these two nosological entities has been revisited in recent years due to the evidence that they share some important clinical and neurobiological features, putting into question the nature and the extent of their commonalities and differences. In this respect, some core symptoms that are present in both disorders, such as social cognitive deficits, could be a primary target of investigation. This review briefly summarizes the commonalities and overlapping features between schizophrenia and autism spectra disorders in social cognitive functions, considering this construct in a Research Domain Criteria perspective. The clinical manifestation of deficits in social cognition are similar in schizophrenia spectrum disorders and autism spectrum disorders, and brain areas that appear to be altered in relation to these impairments are largely shared; however, the results of various studies suggest that, in some cases, the qualitative nature of these alterations may be different in the two spectra. Moreover, relevant differences could be present at the level of brain networks and connections. More research is required in this field, regarding molecular and genetic aspects of both spectra, to better define the neurobiological mechanisms involved in social cognition deficits, with the objective of developing specific and targeted treatments.

Influence of Two Single-Nucleotide Polymorphisms of the Oxytocin Receptor Gene (OXTR) on Empathy: the Mediation Role of a Primary Emotion, CARE

To feel other's pain would elicit empathy. Some theorists hypothesized that observing other's pain may activate the primary emotion of maternal care instinct, which may function as a precursor of empathy. The maternal care instinct and empathy share the same genetic background and neuroendocrine underpinnings. An extensive body of research has shown that maternal behaviors relate to the oxytocinergic system, which has a strong influence on empathy. These studies suggest that the maternal care instinct may mediate the effect of oxytocin receptor gene (OXTR) on empathy. To provide evidence for this mediation, we used the subscale of CARE in Affective Neuroscience Personality Scales (ANPS) to measure the maternal care instinct and tested two OXTR single-nucleotide polymorphisms (SNPs), rs53576 and rs13316193, in 880 high school participants (588 females, 292 males; M_age = 16.51 years old, SD = 0.65). Results showed that the genotype of rs13316193 was indirectly associated with empathy via CARE, suggesting a mediating role of CARE in the pathway from OXTR to empathy. These findings may contribute to an understanding of how empathy emerges when one witnesses another person in pain.