The biochemistry of love: an oxytocin hypothesis

Compassion Focused Group Psychotherapy for attachment and relational trauma: Engaging people with a diagnosis of personality disorder

OBJECTIVES

The research aimed to evaluate an exploratory Compassion Focused Group Psychotherapy Programme and the impact on participants' experiences of self-criticism, usage of services and general wellbeing. Participants included patients with a history of complex attachment and relational trauma (A&RT), who might attract a diagnosis of personality disorder.

DESIGN

This study utilised a quasi-experimental non-randomised within subject controlled design for the evaluation of the efficacy of the programme.

METHODS

Participants were recruited from tertiary care services. The programme consisted of a 12-week Preparation and Engagement intervention (PEG) which was Compassionate Mind Training and Psychoeducation, followed by a 40-week Compassion Focused Trauma Group intervention. The cohort was then followed up after 12 months during which period they received treatment as usual. A comprehensive selection of self-report measures was administered at various points during the therapeutic process and following completion of the group interventions.

RESULTS

The results of the research showed that the provision of a long-term, slow-paced, Compassion Focused Group Psychotherapy intervention, resulted in significant changes across all measures which were maintained at 12-month follow-up. These significant results were maintained following intention to treat and reliable change analyses. These data were supported by a significant reduction in service usage and a significant increase in engagement in employment and education.

CONCLUSIONS

This study has identified that within Compassion Focused Group Psychotherapy, there is a therapeutic process of establishing group-based safeness as a necessary precursor to cultivating compassion and reworking early shame-based trauma memories.

What's love got to do with jealousy?

Romantic love and jealousy seem antagonistic, but the expression of both emotions have evolutionary functions that can go in the same direction of maintaining a relationship. Considering natural selection designed adaptations to solve the problems surrounding reproduction, then love and romantic jealousy are emotions aimed at staying cooperative for a period of time, where love solves the adaptive challenges of promoting pair bonding, cooperation, and protecting offspring; and jealousy is triggered by a threat or the loss of a valuable cooperative relationship, either on behalf of descendants in need of resources, or a close romantic bond. Consequently, understanding love and romantic jealousy points in the same adaptive functional domain of protecting a romantic pair bond. Specifically, love can be comprehended in two different ways and in regard to jealousy. First, conceiving love as the attachment to significant others one develops throughout lifetime, and secondly, it contemplates affective dependence. Results from a sample of single and committed individuals (n = 332) show the predicted positive correlation between attachment and jealousy as stable traits, consistent with previous literature. In addition, there is a non-significant and low correlation, respectively, between attachment and love as a measure of dependence. Furthermore, in the single participants group, jealousy was associated with love. The discussion emphasizes the need for expanding a functional account of love and jealousy as complementary emotions of our human affective endowment. Finally, it would be informative to study attachment as a relational trait and love as a specific affection for a romantic partner that could be manipulated to elucidate the functional design of jealousy.

Examining the Relations Between Children's Vagal Flexibility Across Social Stressor Tasks and Parent- and Clinician-Rated Anxiety Using Baseline Data from an Early Intervention for Inhibited Preschoolers

Early behavioral inhibition (BI) is a known risk factor for later anxiety disorder. Variability in children's parasympathetic nervous system (PNS) functioning may provide insight into the substantial heterogeneity in anxiety outcomes for children high in BI. However, gaps persist due to an over-reliance on static measures of functioning, which limits our ability to leverage PNS functioning to identify risk for anxiety. We address these gaps using baseline data from an early intervention study of inhibited preschoolers by characterizing vagal flexibility (VF), an index of non-linear change in PNS functioning, across social stressor tasks and by examining the associations between VF and anxiety. One hundred and fifty-one parents and their 3.5- to 5-year-old children were selected on the basis of BI to participate in an early intervention program (ClinicalTrials.gov registration: NCT02308826). A structural equation modeling framework was used to model children's VF across tasks designed to mimic exposure to novel social interactions and to test the predictive links between VF and anxiety. Children who showed less VF, characterized by less suppression and flatter recovery, were rated by both parents and clinicians as more anxious. Moreover, a multiple group model showed that children meeting diagnostic criteria for social anxiety disorder demonstrated significantly less VF across social stressor tasks. Among inhibited youth, reduced VF is a risk factor for anxiety and may reflect an individual's reduced capacity to actively cope with external demands. Study results contribute to our understanding of the regulatory processes underlying risk for anxiety in early childhood.

Differential effects of continuous and intermittent daytime food deprivation periods on metabolism and reproductive performance in diurnal zebra finches

We investigated whether food availability effects on metabolism and reproduction are the result of the sum effect of daily feeding (food availability) and starvation (food deprivation) periods. Adult zebra finches were paired and subjected to a time-restricted feeding (TRF) regimen consisting of continuous and intermittent daytime food deprivation periods. Birds were given food during the 12-h day for a total of 4-h in the evening (1 *4-h, hour 8-12), or in 2 splits of 2 h each (2 * 2-h) or 4 splits 1 h each (4 * 1-h), with controls on food ad libitum, until they had the first egg clutch. TRF caused significant changes in hepatic expression of metabolism-associated sirt1, egr1, pparα and foxo1 genes despite no difference in the food intake, body mass and blood glucose levels. Importantly, TRF resulted in a significant reduction in plasma testosterone and estradiol levels, delayed nest-building and egg laying, and reduced clutch size. Concurrently, under TRF regimes, we found a significantly lower expression of th and mtr genes linked with motivation and affiliation (but not of dio2, dio3, gnrh1 and gnih genes linked with gonadal maturation) in the hypothalamus, and of star and hook 1 genes in the testes and star, cyp19 and erα genes in the ovary. These results demonstrate the importance of daily food deprivation times on the metabolism and reproduction, and suggest a possible provisioning of energy available from daily feeding for the maintenance of body condition at the expense of reproduction performance in diurnal animals.

Witches, potions, and metabolites: an overview from a medicinal perspective

Witches were popularly imagined as older women (above middle age), with large warty noses, whose clothes were shabby and used pointy hats. They are usually associated with a cauldron and...

The Logical Case for Love as an Ingredient in Policy Formulation After COVID-19

In the backdrop of the COVID-19 pandemic, which has already had disastrous public health and economic effects, but also resulted in the positive emotion of love as a spontaneous response at many levels, this article asks whether there is a need for the explicit inclusion of the emotion of love in policy formulation. It answers this affirmatively by first proposing, in Part I, what love should mean in policy formulation. However, as rationality remains highly prized in policy formulation, it considers emotion as prejudicial to its cool and level-headed processes and assumes that human behaviour is exclusively negative. To overcome this drawback, love is proposed for inclusion in policy formulation on the rationale that it is a real and positive emotion. Part II takes an eclectic approach and provides six examples of love's relevance drawn from hate studies, medicine, business, psychology, religion, and women's preferences. Together, they constitute a significant pattern and demonstrate love's versatility, making it relevant for those who formulate policy. Suggestions for policy applications are also made. While acknowledging that including love in policy formulation is not a panacea, this positive, universal, and resilient emotion should be incorporated in policy formulation to increase its effectiveness and relevance given the exceptional negativity of our times following COVID-19.

Aggression: Perspectives from social and systems neuroscience

Exhibiting behavioral plasticity in order to mount appropriate responses to dynamic and novel social environments is crucial to the survival of all animals. Thus, how animals regulate flexibility in the timing, duration, and intensity of specific behaviors is of great interest to biologists. In this review, we discuss how animals rapidly respond to social challenges, with a particular focus on aggression. We utilize a conceptual framework to understand the neural mechanisms of aggression that is grounded in Wingfield and colleagues' Challenge Hypothesis, which has profoundly influenced how scientists think about aggression and the mechanisms that allow animals to exhibit flexible responses to social instability. Because aggressive behavior is rooted in social interactions, we propose that mechanisms modulating prosocial behavior may be intricately tied to mechanisms of aggression. Therefore, in order to better understand how aggressive behavior is mediated, we draw on perspectives from social neuroscience and discuss how social context, species-typical behavioral phenotype, and neural systems commonly studied in relation to prosocial behavior (i.e., neuropeptides) contribute to organizing rapid responses to social challenges. Because complex behaviors are not the result of one mechanism or a single neural system, we consider how multiple neural systems important for prosocial and aggressive behavior (i.e., neuropeptides and neurosteroids) interact in the brain to produce behavior in a rapid, context-appropriate manner. Applying a systems neuroscience perspective and seeking to understand how multiple systems functionally integrate to rapidly modulate behavior holds great promise for expanding our knowledge of the mechanisms underlying social behavioral plasticity.

The effects of oxytocin administration on individuals with ASD: Neuroimaging and behavioral evidence

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by difficulties in social communication and the presence of restricted interests and repetitive behaviors. Although behavioral interventions are numerous, there are no Federal Drug Administration approved pharmacological treatments for the core symptoms of ASD. The neuropeptide oxytocin has been studied in animals for decades, and is involved in pair bonding and social affiliation. Given oxytocin's involvement in social communication in animals, researchers have begun exploring whether oxytocin administration in humans affects social behaviors and attachment. Particular attention has been paid to whether oxytocin has therapeutic benefits for improving social behaviors in individuals with ASD. Research on oxytocin administration in ASD has utilized both behavioral and brain-based outcomes. This chapter reviews the effects of oxytocin administration in ASD, with a focus on functional outcomes from neuroimaging investigations. Evidence of potential therapeutic benefits are reviewed, as well as limitations of extant research. A proposed model for future research into the therapeutic benefits of oxytocin includes combining pharmacological (e.g. oxytocin) and behavioral (e.g. evidence-based behavioral interventions) techniques to improve social communication skills in ASD.

Psychobiology of Attachment and Trauma-Some General Remarks From a Clinical Perspective

Attachment refers to a psychobiological principle that is deeply rooted in evolutionary development; it is thought to contribute a major advantage in the survival of the social group. Within individual development it indicates a primary motivational system that guides the initial transactions between mother and baby and furthermore mediates affective attunement and regulation. Psychosocial learning, in close interaction with genetics and epigenetics, also develops a decisive foundation for further brain development of the infant. Finally, the attachment pattern established forms an enduring, relational context for later affective, cognitive, and social development of the child. As an unconsciously active matrix for future personal relationships it has a particular impact on the comprehensive psychological functions of empathy and mentalization. Early adverse and traumatic experiences or major emotional neglect may lead to different levels of security versus insecurity or disorientation-disorganization of the attachment pattern that corresponds to characteristic features of neurobiological regulation.

The quantity-quality trade-off: differential effects of daily food times on reproductive performance and offspring quality in diurnal zebra finches

Abundant food supply is crucial to reproductive performance, as shown by restricted food availability experiments, in small-sized vertebrates including birds. However, whether daily times of feeding would affect the reproduction is largely unknown. Present study investigated the effects of daily food availability times on reproductive performance and quality of eggs and offspring survivors in zebra finches (Taeniopygia guttata). To randomly paired birds kept under 12 h light per day for about 52 weeks, food availability period was restricted to 4 h in morning (FA-M) or evening (FA-E), with controls on food ad libitum; thus, daily food deprivation period began after 4 h of food in FA-M and was continuous with nighttime starvation in FA-E. Both food restrictions adversely affected reproductive health as shown by reduced sex steroids and mesotocin levels, but not general metabolism as indicated by no-difference in thyroxin and triiodothyronine levels. Food for 4 h negatively affected the reproductive performance, although with differences between FA-M and FA-E pairs. Particularly, there was delayed onset of reproduction and compromised reproductive success in FA-E, but not in FA-M pairs; conversely, the offspring health was severely compromised in FA-M, but not in FA-E pairs. Furthermore, FA-M females were in better health, implicating sex-biasness in parental food provisioning. Overall, we demonstrate trade-off of ‘quantity’ (offspring produced and/ or survived) for ‘quality’ (how good offspring were in health) in response to daily food availability times in zebra finches that much like humans are diurnal and retain the ability to reproduce throughout the year.

Love, Emotion and the Singularity

Proponents of the singularity hypothesis have argued that there will come a point at which machines will overtake us not only in intelligence but that machines will also have emotional capabilities. However, human cognition is not something that takes place only in the brain; one cannot conceive of human cognition without embodiment. This essay considers the emotional nature of cognition by exploring the most human of emotions—romantic love. By examining the idea of love from an evolutionary and a physiological perspective, the author suggests that in order to account for the full range of human cognition, one must also account for the emotional aspects of cognition. The paper concludes that if there is to be a singularity that transcends human cognition, it must be embodied. As such, the singularity could not be completely non-organic; it must take place in the form of a cyborg, wedding the digital to the biological.

Ethnopharmacology of Love

Background: Elixirs conferring eternal youth or inducing amatory and erotic attraction have been searched for without success. Lovesickness is a widespread affliction resulting from unrequited love and/or the impossibility for physical and emotional union. The symptoms are reflections of altered dopamine, serotonin, noradrenaline, testosterone and cortisol levels and range from frenzy and intrusive thinking to despair and depression, sharing traits with the neurochemistry of addiction and compulsive behavior disorder. Although it can seriously impact the quality of life, lovesickness is currently not considered in official disease classification systems. Consequently, no official therapeutic guidelines exist, leaving subjects to seek the cure on their own. Methods: We review literature of the past 2000 years dealing with the concept, diagnosis and the healing of lovesickness and contextualize it with neurochemical, ethnomedical, and ethnographic data. Since neurobiological and pharmacological connections between the love drive and the sex drive exist, we review also the literature about herbal an- and aphrodisiacs, focusing on their excitatory or calmative potential. Results: An overall consensus regarding socio-behavioral regimes exists for dealing with lovesickness from historical through contemporary literature. The herbal drugs used for treating lovesickness or inducing love passion do not possess the alleged properties. The pharmacological effects of aphrodisiacs are heterogeneous, including dopaminergic and adrenergic activities, but there is no evidence for any serotonergic effects. The libido-regulating properties of anaphrodisiacs seem to be associated with sedative and toxic effects or decreasing testosterone levels. CB2 receptors expressed on dopaminergic neurons of the ventral tegmental area, part of the brain's reward circuit, implicated with addiction, orgasm and strong emotions such as love, might constitute a new therapeutic target. Conclusion: The common food additive and CB2 agonist β-caryophyllene might have the potential to attenuate dopaminergic firing, quenching the reward and thus motivation associated with romantic love. From Greek mythology to modern history, cultural expressions and implications of love, sex and procreation is and was organized along hierarchical lines that put men on top. The neuronal predispositions and activities associated with falling in love will probably forever remain nature's and Eros' secret.

Mechanistic substrates of a life history transition in male prairie voles: Developmental plasticity in affiliation and aggression corresponds to nonapeptide neuronal function

Although prairie vole (Microtus ochrogaster) social behavior is well-characterized in adults, surprisingly little is known about the development of social behavior in voles. Further, the overwhelming majority of studies in prairie voles examine social behavior in a reproductive context. Here, we examine developmental plasticity in affiliation and aggression and their underlying neural correlates. Using sexually naïve males, we characterized interactions with an age-matched, novel, same-sex conspecific in four different age groups that span pre-weaning to adulthood. We found that prosocial behavior decreased and aggression increased as males matured. Additionally, pre-weaning males were more prosocial than nonsocial, whereas post-weaning males were more nonsocial than prosocial. We also examined nonapeptide neural activity in response to a novel conspecific in brain regions important for promoting sociality and aggression using the immediate early gene cFos. Assessment of developmental changes in neural activity showed that vasopressin neurons in the medial bed nucleus of the stria terminalis exhibit functional plasticity, providing a potential functional mechanism that contributes to this change in sociality as prairie voles mature. This behavioral shift corresponds to the transition from a period of allopatric cohabitation with siblings to a period of time when voles disperse and presumably attempt to establish and defend territories. Taken together our data provide a putative mechanism by which brain and behavior prepare for the opportunity to pairbond (characterized by selective affiliation with a partner and aggression toward unfamiliar conspecifics) by undergoing changes away from general affiliation and toward selective aggression, accounting for this important life history event.

Oxytocin plasma levels in orgasmic and anorgasmic women

The study aimed to evaluate oxytocin (Oxt) serum levels before and after sexual intercourse in women affected by anorgasmia. The sample was constituted of 15 anorgasmic women and 16 orgasmic women. The Female Sexual Function Index (FSFI, cutoff ≤26.55) and the Female Sexual Distress Scale (FSDS, cutoff ≥15) questionnaires were used to assess sexual function and sexual distress, respectively. Serum Oxt levels were measured before sexual intercourse (T0) and 5 min after coital sexual activity (T1). Anorgasmic women had an unpleasant sexual experience (FSFI total score, 20.1 ± 1.2;) and were stressed (FSDS score, 19.4 ± 1.3), whereas orgasmic women were fully satisfied with their sexual activity (FSFI total score 28.7 ± 1.3; FSDS score 11.5 ± 1.8). At T0, anorgasmic women had lower levels of Oxt than orgasmic women, 1.8 ± 0.2 pg/mL versus 2.1 ± 0.5 pg/mL, respectively, [95% CI: (-0.58, -0.01); p < .04]. At T1, Oxt levels did not change in anorgasmic women (1.8 ± 0.2 pg/mL versus 2 ± 0.4 pg/mL, p = .09). Finally, orgasmic women had higher levels of Oxt than anorgasmic women, 4.6 ± 0.7 pg/mL versus 2 ± 0.4 pg/mL, respectively [95% CI: (-3.02, -2.17); p < .001]. The repetitive processes to experience the sexual body sensations could represent a survival behavior of species by attachment to a partner.

The role of oxytocin in the pathogenesis and treatment of schizophrenia

Introduction: Until recently, oxytocin was mainly associated with the pathophysiology of childbirth and sexual functions, but lately this hormone has become the object of interest to psychiatry and psychology due to the significant influence of oxytocin on human behavior in the field of social and emotional functioning. Current scientific research focuses on the participation of oxytocin in the pathogenesis and therapy of mental disorders.

Aim: The aim of the paper is to present, on the basis of available literature, the significance of oxytocin for various psychological functions, with particular emphasis on the influence of oxytocin on the course and clinical picture of schizophrenia.

Method: Available articles from the Medline / PubMed database were analyzed, which were searched using keywords: oxytocin, schizophrenia, therapeutic use of oxytocin, social cognition, positive symptoms, negative symptoms and time descriptors: 2013-2017. There are included articles published in Polish and English.

Results:The research results carried out so far suggest that oxytocin plays a significant role in modulating complex socio-emotional behaviors in schizophrenic patients. The existing research results also indicate a relationship between the dysregulation of the oxytocinergic system and the pathophysiology of schizophrenia. Many of the studies prove that there is a relationship between the level of oxytocin in the patients' blood plasma and the severity of the disease symptoms. Recent genetic studies indicate a possible relationship between polymorphism of oxytocin genesand polymorphism of oxytocin receptor genes and the risk of developing schizophrenia.

Conclusions: Contemporary research on the therapeutic potential of oxytocin and its influence on the functioning of schizophrenia patients seem to be very promising and may contribute to increasing the effectiveness of treatment of schizophrenia and possibly other mental disorders, which in turn will improve the quality of life of patients in cognitive, social and emotional functioning.

Love Influences Reproductive Success in Humans

As love seems to be universal, researchers have attempted to find its biological basis. However, no studies till date have shown its direct association with reproductive success, which is broadly known to be a good measure of fitness. Here, we show links between love, as defined by the Sternberg Triangular Theory of Love, and reproductive success among the Hadza-traditional hunter-gatherer population. We found that commitment and reproductive success were positively and consistently related in both sexes, with number of children showing negative and positive associations with intimacy and passion, respectively, only among women. Our study may shed new light on the meaning of love in humans' evolutionary past, especially in traditional hunter-gatherer societies in which individuals, not their parents, were responsible for partner choice. We suggest that passion and commitment may be the key factors that increase fitness, and therefore, that selection promoted love in human evolution. However, further studies in this area are recommended.

Endogenous Oxytocin, Vasopressin, and Aggression in Domestic Dogs

Aggressive behavior in dogs poses public health and animal welfare concerns, however the biological mechanisms regulating dog aggression are not well understood. We investigated the relationships between endogenous plasma oxytocin (OT) and vasopressin (AVP)-neuropeptides that have been linked to affiliative and aggressive behavior in other mammalian species-and aggression in domestic dogs. We first validated enzyme-linked immunosorbent assays (ELISAs) for the measurement of free (unbound) and total (free + bound) OT and AVP in dog plasma. In Experiment 1 we evaluated behavioral and neuroendocrine differences between a population of pet dogs with a history of chronic aggression toward conspecifics and a matched control group. Dogs with a history of aggression exhibited more aggressive behavior during simulated encounters with conspecifics, and had lower free, but higher total plasma AVP than matched controls, but there were no group differences for OT. In Experiment 2 we compared OT and AVP concentrations between pet dogs and a population of assistance dogs that have been bred for affiliative and non-aggressive temperaments, and investigated neuroendocrine predictors of individual differences in social behavior within the assistance dog population. Compared to pet dogs, assistance dogs had higher free and total OT, but there were no differences in either measure for AVP. Within the assistance dog population, dogs who behaved more aggressively toward a threatening stranger had higher total AVP than dogs who did not. Collectively these data suggest that endogenous OT and AVP may play critical roles in shaping dog social behavior, including aspects of both affiliation and aggression.

I love you from the bottom of my hypothalamus: The role of stress physiology in romantic pair bond formation and maintenance

Monogamous pair bonds helped solve ancestral problems pertinent to our survival as a species. In order for these pair bonds to succeed, biological systems were co-opted to support and reinforce attachment bonds through feelings of pleasure and reward. One of the major biological systems that may play an important role in the formation of romantic attachments is the stress response system (autonomic nervous system and hypothalamic-pituitary-adrenal axis). Research suggests attraction, mate preference, and emotional connectedness may be supported by the activation or inhibition of the stress response system. Further, as romantic relationships progress, new findings suggest partners' physiological patterns coalesce, potentially serving a regulatory function that reinforces the pair bond and affects overall well-being. Based on this evidence, the current paper puts forth the Physiology of Romantic Pair Bond Initiation and Maintenance Model, which will provide researchers with a new perspective on the function of the stress response system in romantic relationships.

Oxytocin and Interpersonal Relationships

The neuropeptide oxytocin (OT) has emerged as a potent modulator of diverse aspects of interpersonal relationships. OT appears to work in close interaction with several other neurotransmitter networks, including the dopaminergic reward circuit, and to be dependent on sex-specific hormonal influences. In this chapter, we focus on four main domains of OT and interpersonal relationships, including (1) the protective effect of OT on an individual's ability to withstand stress (i.e., stress buffering), (2) the effect of OT on emotion recognition and empathy, (3) OT's ability to enhance social synchrony and cooperation among individuals, and (4) the effect of OT on an individual's perception of social touch. We then illustrate the connection between OT and loneliness while grieving the loss of a loved one. We finish by discussing the clinical potential of OT, focusing on its potential role as an adjunct to psychotherapy, its enhancement through sex-specific hormonal influences, and the difficulties that present themselves when considering OT as a therapy. Overall, we argue that OT continues to hold strong therapeutic promise, but that it is strongly dependent on internal and external influences, for instance the patient's personal past experiences and interaction with the therapist, in order to provide the best possible therapy.

Oxytocin and Human Evolution

A small, but powerful neuropeptide, oxytocin coordinates processes that are central to both human reproduction and human evolution. Also embedded in the evolution of the human nervous system are unique pathways necessary for modern human sociality and cognition. Oxytocin is necessary for facilitating the birth process, especially in light of anatomical restrictions imposed by upright human locomotion, which depends on a fixed pelvis. Oxytocin, by facilitating birth, allowed the development of a large cortex and a protective bony cranium. The complex human brain in turn permitted the continuing emergence of social sensitivity, complex thinking, and language. After birth is complete, oxytocin continues to support human development by providing direct nutrition, in the form of human milk, and emotional and intellectual support through high levels of maternal behavior and selective attachment. Oxytocin also encourages social sensitivity and reciprocal attunement, on the part of both the mother and child, which are necessary for human social behavior and for rearing an emotionally healthy human child. Oxytocin supports growth during development, resilience, and healing across the lifespan. Oxytocin dynamically moderates the autonomic nervous system, and effects of oxytocin on vagal pathways allowing high levels of oxygenation and digestion necessary to support adaptation in a complex environment. Finally, oxytocin has anti-oxidant and anti-inflammatory effects, helping to explain the pervasive adaptive consequences of social behavior for emotional and physical health.

Oxytocin and Memory of Emotional Stimuli: Some Dance to Remember, Some Dance to Forget

An ever-growing body of evidence suggests that the hypothalamic neuropeptide oxytocin plays a central role in the regulation of mammalian social behavior and relationships. Yet, mammalian social interactions are extremely complex, involving both approach and avoidance behaviors toward specific individuals. While in the past oxytocin was conceived merely as a prosocial molecule that nonselectively facilitated affiliative emotions and behavior, it is now recognized that oxytocin plays a role in a wide range of social relationships, some of which involve negative emotions such as fear, aggression, and envy and lead to avoidance behavior. However, the way by which a single molecule such as oxytocin contributes to contrasting emotions and opposite behaviors is yet to be discovered. Here, we discuss the role of oxytocin in the modulation of emotional memories in rodents, focusing on two paradigms: social recognition and fear conditioning, representing approach and avoidance behaviors, respectively. We review recent pioneering studies that address the complex effects of oxytocin in a mechanistic approach, using genetic animal models and brain region-specific manipulations of oxytocin activity. These studies suggest that the multiple roles of oxytocin in social and fear behavior are due to its local effects in various brain areas, most notably distinct regions of the amygdala. Finally, we propose a model explaining some of the contradictory effects of oxytocin as products of the balance between two networks in the amygdala that are controlled by the medial prefrontal cortex.

Compared to what: What can we say about nonapeptide function and social behavior without a frame of reference?

Our understanding of behavior and mechanism is undermined by the absence of a frame of reference because relationships between individuals and species are without context. We highlight a need to be more comparative, using nonapeptide (vasopressin and oxytocin) modulation of social behavior as an example. We reconsider the use of model organisms and the term 'social' in this context, contrasting two popular models for nonapeptide regulation of social behavior. We then propose that a frame of reference should be established by studying mechanisms of behavior across taxa along the same continua. If we are to ever establish a unifying theory of behavior, we must transcend individual examples and determine the relative relationships of behavior and mechanism among and between species.

Association of Oxytocin Receptor Gene (OXTR) rs53576 Polymorphism with Sociality: A Meta-Analysis

A common variant in the oxytocin receptor gene (OXTR), rs53576, has been broadly linked to socially related personality traits and behaviors. However, the pattern of published results is inconsistent. Here, we performed a meta-analysis to comprehensively evaluate the association. The literature was searched for relevant studies and effect sizes between individuals homozygous for the G allele (GG) and individuals with A allele carriers (AA/AG). Specifically, two indices of sociality were evaluated independently: i) general sociality (24 samples, n = 4955), i.e., how an individual responds to other people in general; and ii) close relationships (15 samples, n = 5262), i.e., how an individual responds to individuals with closed connections (parent-child or romantic relationship). We found positive association between the rs53576 polymorphism and general sociality (Cohen’s d = 0.11, p = .02); G allele homozygotes had higher general sociality than the A allele carriers. However, the meta-analyses did not detect significant genetic association between rs53576 and close relationships (Cohen’s d = 0.01, p = .64). In conclusion, genetic variation in the rs53576 influences general sociality, which further implies that it is worthy to systematically examine whether the rs53576 is a valid genetic marker for socially related psychiatric disorders.

Sensitive periods in human social development: New insights from research on oxytocin, synchrony, and high-risk parenting

Sensitive periods (SP) in behavioral development appeared in the biological sciences during the first decade of the 20th century, and research in animal models beginning in the 1950s provide terminology and evidence for SP effects. This paper proposes a rigorous program for human SP research and argues that the complexity of the human brain and variability of the human ecology necessitate that SP effects must be studied in humans, employ longitudinal designs starting at birth, test mechanism-based hypotheses based on animal studies that manipulate early environments, and utilize high-risk conditions as “natural experiments.” In light of research on the molecular basis of critical periods and their sequential cascades, it is proposed that the oxytocin (OT) system, an ancient and integrative system that cross-talks with the stress, reward, immune, and brain stem mediated homeostatic systems and supports mammalian sociality, plays a unique role in experience-dependent plasticity that buttresses SP effects due to its (a) dendritic mode of release leading to autoregulated functioning primed by early experience, (b) pulsatile pattern of activity, and (c) special role in neural plasticity at the molecular and network assembly levels. Synchrony, the coordination of biology and behavior during social contact, is suggested as a mechanism by which SP exert their effect on OT functionality, the social brain, and adult sociality. Findings from four high-risk birth cohorts, each followed repeatedly from birth to 10 years, provide unique “natural experiments” for human SP research based on specific programs in animal models. These include prematurity (maternal proximity), multiple birth (peer rearing), postpartum depression (low licking and grooming), and chronic unpredictable trauma (maternal rotation, variable foraging demands). In each cohort, hypotheses are based on the missing environmental component during SP, and findings on social synchrony, OT functionality, stress response, emotion regulation, and mental health accord with the multilevel and dynamic principles of developmental psychopathology. The results on the potential for reparation versus chronicity following early deprivation highlight a flexible conceptualization of resilience based on human SP research. Consideration of SP effects at the molecular, endocrine, brain, and behavioral levels and in relation to the neural plasticity and multifinality of human social functions may assist in fine-tuning early detection and the construction of targeted individualized interventions.

Evidence for a role of the oxytocin system, indexed by genetic variation in CD38, in the social bonding effects of expressed gratitude

Oxytocin is thought to play a central role in promoting close social bonds via influence on social interactions. The current investigation targeted interactions involving expressed gratitude between members of romantic relationships because recent evidence suggests gratitude and its expression provides behavioral and psychological 'glue' to bind individuals closer together. Specifically, we took a genetic approach to test the hypothesis that social interactions involving expressed gratitude would be associated with variation in a gene, CD38, which has been shown to affect oxytocin secretion. A polymorphism (rs6449182) that affects CD38 expression was significantly associated with global relationship satisfaction, perceived partner responsiveness and positive emotions (particularly love) after lab-based interactions, observed behavioral expression of gratitude toward a romantic partner in the lab, and frequency of expressed gratitude in daily life. A separate polymorphism in CD38 (rs3796863) previously associated with plasma oxytocin levels and social engagement was also associated with perceived responsiveness in the benefactor after an expression of gratitude. The combined influence of the two polymorphisms was associated with a broad range of gratitude-related behaviors and feelings. The consistent pattern of findings suggests that the oxytocin system is associated with solidifying the glue that binds adults into meaningful and important relationships.

The role of oxytocin in male and female reproductive behavior

Oxytocin (OT) is a nonapeptide with an impressive variety of physiological functions. Among them, the 'prosocial' effects have been discussed in several recent reviews, but the direct effects on male and female sexual behavior did receive much less attention so far. As our contribution to honor the lifelong interest of Berend Olivier in the control mechanisms of sexual behavior, we decided to explore the role of OT in the present review. In the successive sections, some physiological mechanisms and the 'pair-bonding' effects of OT will be discussed, followed by sections about desire, female appetitive and copulatory behavior, including lordosis and orgasm. At the male side, the effects on erection and ejaculation are reviewed, followed by a section about 'premature ejaculation' and a possible role of OT in its treatment. In addition to OT, serotonin receives some attention as one of the main mechanisms controlling the effects of OT. In the succeeding sections, the importance of OT for 'the fruits of labor' is discussed, as it plays an important role in both maternal and paternal behavior. Finally, we pay attention to an intriguing brain area, the ventrolateral part of the ventromedial hypothalamic nucleus (VMHvl), apparently functioning in both sexual and aggressive behavior, which are at first view completely opposite behavioral systems.

Sex-specific associations between plasma oxytocin levels and schizotypal personality features in healthy individuals

OBJECTIVES

Oxytocin (OT) has been shown to play a crucial role in the biology of social interaction. Sex differences associated with this neuropeptide system have been reported. OT may serves as an indicator of interpersonal stress, especially in women. The aim of this study was to investigate the sex-specific associations between plasma OT levels and schizotypal personality features, especially in interpersonal dimension, in healthy individuals.

METHODS

Ninety six healthy participants, including 41 males and 55 females, were recruited. Fasting blood samples were analyzed by enzyme immunoassay of OT. The Schizotypal Personality Questionnaire (SPQ) was administered. Mann-Whitney U test was used to test the difference between male and female. Spearman's ρ correlation analysis (two-tailed) was carried out to examine the association between OT level and SPQ score.

RESULTS

The results showed that OT level was significantly positively correlated with total score and interpersonal dysfunction dimensional scores of the SPQ only in females.

CONCLUSIONS

Although the causal relationship remains unclear, our findings provide further evidence to support the sexual dimorphic role of OT in interpersonal biology. Moreover, the effect of sex difference also is taken into consideration.

Oxytocin pathways and the evolution of human behavior

This review examines the hypothesis that oxytocin pathways--which include the neuropeptide oxytocin, the related peptide vasopressin, and their receptors--are at the center of physiological and genetic systems that permitted the evolution of the human nervous system and allowed the expression of contemporary human sociality. Unique actions of oxytocin, including the facilitation of birth, lactation, maternal behavior, genetic regulation of the growth of the neocortex, and the maintenance of the blood supply to the cortex, may have been necessary for encephalization. Peptide-facilitated attachment also allows the extended periods of nurture necessary for the emergence of human intellectual development. In general, oxytocin acts to allow the high levels of social sensitivity and attunement necessary for human sociality and for rearing a human child. Under optimal conditions oxytocin may create an emotional sense of safety. Oxytocin dynamically moderates the autonomic nervous system, and effects of oxytocin on vagal pathways, as well as the antioxidant and anti-inflammatory effects of this peptide, help to explain the pervasive adaptive consequences of social behavior for emotional and physical health.