Oxytocin increases anxiety to unpredictable threat

Intranasal oxytocin as a treatment for anxiety and autism: From subclinical to clinical applications

Animal and human studies have demonstrated that intranasal oxytocin (OT) can penetrate the brain and induce cognitive, emotional, and behavioral changes, particularly in social functioning. Consequently, numerous investigations have explored the potential of OT as a treatment for anxiety and autism, conditions characterized by social deficits. Although both subclinical and clinical studies provide converging evidence of the therapeutic effects of OT in reducing anxiety levels and improving social symptoms in autism, results are not always consistent. Additionally, the pharmacological mechanism of OT requires further elucidation for its effective clinical application. Therefore, this review aims to examine the contentious findings concerning the effects of OT on anxiety and autism, offer interpretations of the inconsistent results from the perspectives of individual differences and varying approaches to OT administration, and shed light on the underlying mechanisms of OT. Ultimately, standardization of dosage, frequency of administration, formulation characteristics, and nasal spray devices is proposed as essential for future human studies and clinical applications of OT treatment.

Therapeutic uses of oxytocin in stress-related neuropsychiatric disorders

Oxytocin (OXT), produced and secreted in the paraventricular nucleus and supraoptic nucleus of magnocellular and parvocellular neurons. The diverse presence and activity of oxytocin suggests a potential for this neuropeptide in the pathogenesis and treatment of stress-related neuropsychiatric disorders (anxiety, depression and post-traumatic stress disorder (PTSD)). For a more comprehensive understanding of the mechanism of OXT's anti-stress action, the signaling cascade of OXT binding to targeting stress were summarized. Then the advance of OXT treatment in depression, anxiety, PTSD and the major projection region of OXT neuron were discussed. Further, the efficacy of endogenous and exogenous OXT in stress responses were highlighted in this review. To augment the level of OXT in stress-related neuropsychiatric disorders, current biological strategies were summarized to shed a light on the treatment of stress-induced psychiatric disorders. We also conclude some of the major puzzles in the therapeutic uses of OXT in stress-related neuropsychiatric disorders. Although some questions remain to be resolved, OXT has an enormous potential therapeutic use as a hormone that regulates stress responses.

Chronic oxytocin-driven alternative splicing of Crfr2α induces anxiety

The neuropeptide oxytocin (OXT) has generated considerable interest as potential treatment for psychiatric disorders, including anxiety and autism spectrum disorders. However, the behavioral and molecular consequences associated with chronic OXT treatment and chronic receptor (OXTR) activation have scarcely been studied, despite the potential therapeutic long-term use of intranasal OXT. Here, we reveal that chronic OXT treatment over two weeks increased anxiety-like behavior in rats, with higher sensitivity in females, contrasting the well-known anxiolytic effect of acute OXT. The increase in anxiety was transient and waned 5 days after the infusion has ended. The behavioral effects of chronic OXT were paralleled by activation of an intracellular signaling pathway, which ultimately led to alternative splicing of hypothalamic corticotropin-releasing factor receptor 2α (Crfr2α), an important modulator of anxiety. In detail, chronic OXT shifted the splicing ratio from the anxiolytic membrane-bound (mCRFR2α) form of CRFR2α towards the soluble CRFR2α (sCRFR2α) form. Experimental induction of alternative splicing mimicked the anxiogenic effects of chronic OXT, while sCRFR2α-knock down reduced anxiety-related behavior of male rats. Furthermore, chronic OXT treatment triggered the release of sCRFR2α into the cerebrospinal fluid with sCRFR2α levels positively correlating with anxiety-like behavior. In summary, we revealed that the shifted splicing ratio towards expression of the anxiogenic sCRFR2α underlies the adverse effects of chronic OXT treatment on anxiety.

From Oxytocin to Compassion: The Saliency of Distress

Compassion is a warm response of care and concern for those who are suffering, which drives individuals to devote their resources for the sake of others. A prominent neuroevolutionary framework grounds compassion in the neurobiology of the mammalian caregiving system. Accordingly, it has been suggested that the oxytocinergic system, which plays a central role in parental caregiving and bonding, provides the neurobiological foundation for compassion towards strangers. Yet, the specific role of oxytocin in compassion is far from clear. The current paper aims to target this gap and offer a theoretical framework that integrates the state-of-the-art literature on oxytocin with research on compassion. We suggest that oxytocin mediates compassion by enhancing the saliency of cues of pain and distress and discuss the plausible underlying neurobiological substrates. We further demonstrate how the proposed framework can account for individual differences in compassion, focusing on the effects of attachment on caregiving and support. The proposed framework integrates the current scientific understanding of oxytocin function with compassion-related processes. It thus highlights the largely ignored attentional processes in compassion and taps into the vast variability of responses in social contexts involving pain and suffering.

Advances in human oxytocin measurement: challenges and proposed solutions

Oxytocin, a neuropeptide known for its role in reproduction and socioemotional processes, may hold promise as a therapeutic agent in treating social impairments in patient populations. However, research has yet to uncover precisely how to manipulate this system for clinical benefit. Moreover, inconsistent use of standardized and validated oxytocin measurement methodologies-including the design and study of hormone secretion and biochemical assays-present unresolved challenges. Human studies measuring peripheral (i.e., in plasma, saliva, or urine) or central (i.e., in cerebrospinal fluid) oxytocin concentrations have involved very diverse methods, including the use of different assay techniques, further compounding this problem. In the present review, we describe the scientific value in measuring human endogenous oxytocin concentrations, common issues in biochemical analysis and study design that researchers face when doing so, and our recommendations for improving studies using valid and reliable methodologies.

Anxiolytic Effects of Chronic Intranasal Oxytocin on Neural Responses to Threat Are Dose-Frequency Dependent

INTRODUCTION

Anxiety disorders are prevalent mental conditions characterized by exaggerated anxious arousal and threat reactivity. Animal and human studies suggest an anxiolytic potential of the neuropeptide oxytocin (OT), yet, while a clinical application will require chronic administration protocols, previous human studies have exclusively focused on single-dose (acute) intranasal OT effects.

OBJECTIVE

To facilitate the translation of the potential anxiolytic mechanism of OT into clinical application, we determined whether the anxiolytic effects of OT are maintained with repeated (chronic) administration or are influenced by dose frequency and trait anxiety.

METHODS

In a pre-registered double-blind randomized placebo-controlled pharmaco-fMRI trial the acute (single dose) as well as chronic effects of two different dose frequencies of OT (OT administered daily for 5 days or every other day) on emotional reactivity were assessed in n = 147 individuals with high versus low trait anxiety (ClinicalTrials.gov ID: NCT03085654).

RESULTS

OT produced valence, dose frequency, and trait anxiety-specific effects, such that the low-frequency (intermittent) chronic dosage specifically attenuated a neural reactivity increase in amygdala-insula-prefrontal circuits observed in the high anxious placebo-treated subjects in response to threatening but not positive stimuli.

CONCLUSIONS

The present trial provides the first evidence that low-dose frequency chronic intranasal OT has the potential to alleviate exaggerated neural threat reactivity in subjects with elevated anxiety levels, suggesting a treatment potential for anxiety disorders.

Oxytocin promotes species-relevant outgroup attention in bonobos and chimpanzees

Previous research has found that oxytocin (OT) is associated with intergroup behaviour in humans as well as wild chimpanzees, and that exogenous OT affects Pan social attention. The two Pan species, bonobos and chimpanzees, differ drastically from one another in their intensity of intergroup competition, with lethal intergroup aggression often led by males in chimpanzees and more tolerant associations often centered around females in bonobos. However, it remains unclear how exogenous OT changes the two species' responses to ingroup and outgroup individuals. In this study, after intranasal administration of nebulized OT or placebo control, chimpanzees and bonobos viewed image pairs of ingroup and outgroup conspecifics while their eye movements were tracked with an eye-tracker. Although the overall effect of OT was small, we found that OT shifted bonobos' and chimpanzees' attention to outgroup images of the sex primarily involved in intergroup encounters in each species. Specifically, OT selectively shifted attention towards outgroup photos of female conspecifics in bonobos, and those of outgroup male conspecifics in chimpanzees. This suggests that OT generally promotes outgroup attention in both bonobos and chimpanzees but this effect is restricted to the sex most relevant in intergroup relations. These results suggest that, although OT may have a generally conserved role in hominid intergroup behaviour, it may act in species-relevant ways under the influence of their socio-ecological backgrounds.

Larval Zebrafish as a Model for Mechanistic Discovery in Mental Health

Animal models are essential for the discovery of mechanisms and treatments for neuropsychiatric disorders. However, complex mental health disorders such as depression and anxiety are difficult to fully recapitulate in these models. Borrowing from the field of psychiatric genetics, we reiterate the framework of 'endophenotypes' - biological or behavioral markers with cellular, molecular or genetic underpinnings - to reduce complex disorders into measurable behaviors that can be compared across organisms. Zebrafish are popular disease models due to the conserved genetic, physiological and anatomical pathways between zebrafish and humans. Adult zebrafish, which display more sophisticated behaviors and cognition, have long been used to model psychiatric disorders. However, larvae (up to 1 month old) are more numerous and also optically transparent, and hence are particularly suited for high-throughput screening and brain-wide neural circuit imaging. A number of behavioral assays have been developed to quantify neuropsychiatric phenomena in larval zebrafish. Here, we will review these assays and the current knowledge regarding the underlying mechanisms of their behavioral readouts. We will also discuss the existing evidence linking larval zebrafish behavior to specific human behavioral traits and how the endophenotype framework can be applied. Importantly, many of the endophenotypes we review do not solely define a diseased state but could manifest as a spectrum across the general population. As such, we make the case for larval zebrafish as a promising model for extending our understanding of population mental health, and for identifying novel therapeutics and interventions with broad impact.

Effects of Chronic and Acute Intranasal Oxytocin Treatments on Temporary Social Separation in Adult Titi Monkeys (Plecturocebus cupreus)

In socially monogamous titi monkeys, involuntary separation from a pair mate can produce behavioral distress and increased cortisol production. The neuropeptide oxytocin (OXT) is thought to play an important role in the separation response of pair-bonded species. Previous studies from our lab have shown that chronic intranasal oxytocin (IN OXT) during development can have long-term effects on adult social behavior. In the current study, we examined the chronic and acute effects of IN OXT or Saline (SAL) on the subjects’ response to a brief separation from their pair mates. Subjects with a history of chronic IN OXT or SAL treatment during development received a single dose of OXT or SAL as adults 30 min before being separated from their pair mate. Chronic treatment consisted of a daily dose of IN OXT (0.8 IU/kg) or SAL (control) from 12 to 18 months of age. Subjects (N = 29) were introduced to a pair mate at 30 months of age. After the pairs had cohabitated for 5 months, pairs underwent two “Brief Separation” (OXT and SAL) and two “Non-Separation” (OXT and SAL) test sessions. Vocalizations and locomotion were measured as behavioral indices of agitation or distress during the Brief Separation and Non-Separation periods (30 min each). We collected blood samples after the Brief Separation and Non-Separation periods to measure cortisol levels. Our results showed subjects treated with chronic OXT had a reduction in long call and peep vocalizations compared to subjects treated with chronic SAL. Subjects treated with chronic SAL and acute OXT produced more peeps and long calls compared to animals treated with acute SAL; however, patterns in this response depended on sex. Cortisol and locomotion were significantly higher during the Brief Separation period compared to the Non-Separation period; however, we did not find any treatment or sex effects. We conclude that chronic IN OXT given during development blunts the separation response, while acute OXT in chronic SAL subjects had sexually dimorphic effects, which could reflect increased partner seeking behaviors in males and increased anxiety in females.

Social isolation modulates appetite and avoidance behavior via a common oxytocinergic circuit in larval zebrafish

Animal brains have evolved to encode social stimuli and transform these representations into advantageous behavioral responses. The commonalities and differences of these representations across species are not well-understood. Here, we show that social isolation activates an oxytocinergic (OXT), nociceptive circuit in the larval zebrafish hypothalamus and that chemical cues released from conspecific animals are potent modulators of this circuit's activity. We delineate an olfactory to subpallial pathway that transmits chemical social cues to OXT circuitry, where they are transformed into diverse outputs simultaneously regulating avoidance and feeding behaviors. Our data allow us to propose a model through which social stimuli are integrated within a fundamental neural circuit to mediate diverse adaptive behaviours.

Impact of social isolation on the oxytocinergic system: A systematic review and meta-analysis of rodent data

Social isolation (SI) stress results from a combination of intrinsic and environmental factors and is associated with a variety of negative developmental outcomes. Oxytocin (OXT) might play a role in the consequences of SI in the brain and periphery. We conducted a systematic review and meta-analysis to compile data about the effects of SI in the oxytocinergic system of rats and mice, and its relation to behavioral alterations. Five databases (EMBASE, PsychNet, PubMed, Scopus, and Web of Science) in March 2021, using ("Social Isolation" AND (mouse OR rat) AND (oxytocin OR oxytocin receptor)). This review followed the PRISMA guidelines, including registration in PROSPERO, and risk of bias assessment. The twelve articles included in this review indicated that SI was associated with decreased OXTR levels, resulting in behavioral alterations like increased aggression and anxiety-like behavior, hyperactivity, and diminished social behaviors and memory. No significant effects on OXT levels were observed. Administration of synthetic OXT or its agonists partially decreases those unwanted behaviors to similar levels of control animals.

Differential effects of the translocator protein 18 kDa (TSPO) ligand etifoxine and the benzodiazepine alprazolam on startle response to predictable threat in a NPU-threat task after acute and short-term treatment

RATIONALE

Benzodiazepines have been extensively investigated in experimental settings especially after single administration, which mostly revealed effects on unpredictable threat (U-threat) rather than predictable threat (P-threat). Given the need for pharmacological alternatives with a preferable side-effect profile and to better represent clinical conditions, research should cover also other anxiolytics and longer application times.

OBJECTIVES

The present study compared the acute and short-term effects of the translocator protein 18 kDa (TSPO) ligand etifoxine and the benzodiazepine alprazolam on P-threat and U-threat while controlling for sedation.

METHODS

Sixty healthy male volunteers, aged between 18 and 55 years, were randomly assigned to receive a daily dose of either 150 mg etifoxine, 1.5 mg alprazolam, or placebo for 5 days. On days 1 and 5 of intake, they performed a NPU-threat task including neutral (N), predictable (P), and unpredictable (U) conditions, while startle responsivity and self-reports were studied. Sedative effects were assessed using a continuous performance test.

RESULTS

Neither alprazolam nor etifoxine affected startle responsivity to U-threat on any of the testing days. While etifoxine reduced the startle response to P-threat on day 1 of treatment for transformed data, a contrary effect of alprazolam was found for raw values. No effects on self-reports and no evidence of sedation could be observed for either drug.

CONCLUSIONS

None of the anxiolytic substances had an impact on startle potentiation to U-threat even after several days of intake. The effects of the anxiolytics on startle responsivity to P-threat as well as implications for future studies are discussed.

Roles of Oxytocin in Stress Responses, Allostasis and Resilience

Oxytocin has been revealed to work for anxiety suppression and anti-stress as well as for psychosocial behavior and reproductive functions. Oxytocin neurons are activated by various stressful stimuli. The oxytocin receptor is widely distributed within the brain, and oxytocin that is released or diffused affects behavioral and neuroendocrine stress responses. On the other hand, there has been an increasing number of reports on the role of oxytocin in allostasis and resilience. It has been shown that oxytocin maintains homeostasis, shifts the set point for adaptation to a changing environment (allostasis) and contributes to recovery from the shifted set point by inducing active coping responses to stressful stimuli (resilience). Recent studies have suggested that oxytocin is also involved in stress-related disorders, and it has been shown in clinical trials that oxytocin provides therapeutic benefits for patients diagnosed with stress-related disorders. This review includes the latest information on the role of oxytocin in stress responses and adaptation.

Medication-Enhanced Psychotherapy for Posttraumatic Stress Disorder: Recent Findings on Oxytocin's Involvement in the Neurobiology and Treatment of Posttraumatic Stress Disorder

Background

Traumatic experiences may result in Posttraumatic Stress Disorder (PTSD), which is characterized as an exaggerated fear response that cannot be extinguished over time or in safe environments. What are beneficial psychotherapeutic treatment options for PTSD patients? Can oxytocin (OXT), which is involved in the stress response, and safety learning, ameliorate PTSD symptomatology and enhance psychotherapeutic effects? Here, we will review recent studies regarding OXT's potential to enhance psychotherapeutic therapies for PTSD treatment.

Method

We conducted a literature review on the neurobiological underpinnings of PTSD especially focusing on OXT's involvement in the biology and memory formation of PTSD. Furthermore, we researched successful psychotherapeutic treatments for PTSD patients and discuss how OXT may facilitate observed psychotherapeutic effects.

Results

For a relevant proportion of PTSD patients, existing psychotherapies are not beneficial. OXT may be a promising candidate to enhance psychotherapeutic effects, because it dampens responses to stressful events and allows for a faster recovery after stress. On a neural basis, OXT modulates processes that are involved in stress, arousal and memory. OXT effectively counteracts memory impairments caused by stress and facilitates social support seeking which is a key resilience factor for PTSD and which is beneficial in psychotherapeutic settings.

Conclusion

OXT has many characteristics that are promising to positively influence psychotherapy for PTSD patients. It potentially reduces intrusions, but preserves memory of the event itself. Introducing OXT into psychotherapeutic settings may result in better treatment outcomes for PTSD patients. Future research should directly investigate OXT's effects on PTSD, especially in psychotherapeutic settings.

Oxytocin-induced anxiogenic behavior in juvenile male rats

Oxytocin (OT) is considered beneficial to mental health owing to its anxiolytic, prosocial, and anti-stress effects; however, the adverse effects of OT have been controversial, such as its potentially anxiogenic actions. Although OT influences drug abuse and reciprocally affects vulnerability to drug use, the relationship between OT’s anxiogenic working and nicotine preference intake has not been clearly defined. To clarify this issue, the effect of acute peripheral administration of OT on anxiety and nicotine preference was investigated in juvenile male rats. Anxiogenic behaviors were noticeably increased in OT-administrated rats, with an increase in serum corticosterone levels. Moreover, increased anxiety-like behaviors and corticosterone levels were observed in the OT analog carbetocin-injected rats. In the nicotine preference test, the rats’ aversive responses to initial nicotine choice and preference were not significantly different between saline-injected and OT-injected rats. However, when administered with OT, there was a significant negative correlation between anxiety-like behavior and low-dose nicotine consumption. Collectively, these results provide evidence that acute OT exposure could induce anxiogenic behavior with corticosterone augmentation, contributing to the attenuation of nicotine preference. This suggests that both aspects of OT, as well as their benefits and drawbacks, should be considered.

Intranasal oxytocin decreases fear generalization in males, but does not modulate discrimination threshold

BACKGROUND

A previously acquired fear response often spreads to perceptually or conceptually close stimuli or contexts. This process, known as fear generalization, facilitates the avoidance of danger, and dysregulations in this process play an important role in anxiety disorders. Oxytocin (OT) has been shown to modulate fear learning, yet effects on fear generalization remain unknown.

METHODS

We employed a randomized, placebo-controlled, double-blind, between-subject design during which healthy male participants received either intranasal OT or placebo (PLC) following fear acquisition and before fear generalization with concomitant acquisition of skin conductance responses (SCRs). Twenty-four to 72 h before the fear learning and immediately after the fear generalization task, participants additionally complete a discrimination threshold task.

RESULTS

Relative to PLC, OT significantly reduced perceived risk and SCRs towards the CS+ and GS1 (the generalization stimulus that is most similar to CS+) during fear generalization, whereas the discrimination threshold was not affected.

CONCLUSIONS

Together, the results suggest that OT can attenuate fear generalization in the absence of effects on discrimination threshold. This study provides the first evidence for effects of OT on fear generalization in humans and suggests that OT may have therapeutic potential in anxiety disorders characterized by dysregulated fear generalization.

Oxytocin intensifies the mortality salience effect: Novel evidence for the social salience model of oxytocin

Oxytocin plays an important role in human responses to threat processing. Few studies have directly examined the effects of oxytocin on our response to death-related stimuli. In the current study, 63 participants intranasally received either 32 IU of oxytocin or a placebo and thereafter completed a visual dot-probe task consisting of death-related and non-death related images. The results indicated that oxytocin enhanced participants' vigilance toward death-related images as well as increased their anxiety about and fear of death. Overall, oxytocin amplifies the defensive responses to a mortality threat, supporting the social salience model of oxytocin.

Sex differences of oxytocin and vasopressin in social behaviors

The neuropeptides oxytocin (OT) and vasopressin (VP) are known to mediate social cognition and behaviors in a sex-dependent manner. This chapter reviews the sex-dependent influence of OT and VP on social behaviors, focusing on (1) partner preference and sexual orientation, (2) memory modulation, (3) emotion regulation, and (4) trust-related behaviors. Most studies suggest that OT promotes familiar (opposite-sex) partner preference, strengthens memory, relieves anxiety, and increases trust. However, VP-regulated social cognition has been studied less than OT. VP facilitates familiar (opposite-sex) partner preference, enhances memory, induces anxiety, and influences happiness/anger perception. Detailed sex differences of these effects are reviewed. There is a male preponderance in the use of animal models and many study results are too complex to draw firm conclusions. Clarifying the complex interplay between the OT/VP system and sex hormones in the regulation of social behaviors is needed.

Activation of septal OXTr neurons induces anxiety- but not depressive-like behaviors

The neuropeptide oxytocin (OXT) is well recognized for eliciting anxiolytic effects and promoting social reward. However, emerging evidence shows that OXT increases aversive events. These seemingly inconsistent results may be attributable to the broad OXT receptor (OXTr) expression in the central nervous system. This study selectively activated septal neurons expressing OXTr using chemogenetics. We found that chemogenetic activation of septal OXTr neurons induced anxiety- but not depressive-like behavior. In addition, septal OXTr neurons projected dense fibers to the horizontal diagonal band of Broca (HDB), and selective stimulation of those HDB projections also elicited anxiety-like behaviors. We also found that septal OXTr neurons express the vesicular GABA transporter (vGAT) protein and optogenetic stimulation of septal OXTr projections to the HDB inactivated HDB neurons. Our data collectively reveal that septal OXTr neurons increase anxiety by projecting inhibitory GABAergic inputs to the HDB.

Revisit the Effectiveness of Educational Kinesiology on Stress and Anxiety Amelioration in Kindergarteners With Special Needs Using Biological Measures

Background: Educational kinesiology is a popular intervention that aims to improve brain functioning via physical movements. Yet, it lacks supporting scientific evidence and is regarded as pseudoscience. Given the popularity of educational kinesiology in school settings, it is important to revisit its effectiveness through scientific research. Previous studies that evaluated the effectiveness of educational kinesiology relied mainly on subjective measures, in which subjective bias is inevitable. Cortisol and oxytocin levels in saliva have been reported to be reliable stress and anxiety markers that provide unbiased objective data. This study explores the effect of educational kinesiology on the changes in salivary cortisol and oxytocin levels in kindergarteners with special needs. Methods: A quasi-experimental design was adopted in this study. Thirty-seven kindergarteners (3.5-6.5 years old) who were either diagnosed with one type of special needs or referred by school principals due to the requirement of special supports at school were assigned to either the intervention group, which received 1-h educational kinesiology intervention weekly for a total of 10 weeks, or the wait-list control group. Saliva samples were collected at baseline and after the completion of intervention programme for the measurement of cortisol and oxytocin levels. Scores of Parent-rated Preschool Anxiety Scale (PAS-TC) were also collected at pre- and post-intervention. Because of the small samples, non-parametric tests such as Mann-Whitney U test, Quade test, and Fisher's exact tests were used in this study where appropriate. Results: After controlled for the effect at baseline, gender and types of special needs, the changes in oxytocin levels were significantly higher in the intervention group compared with control [F _{(1, 35)} = 4.747, p = 0.036, eta² = 0.119], whereas no significant between-group difference in changes of cortisol levels was observed [F _{(1, 35)} = 0.306, p = 0.584, eta² = 0.009]. Results from PAS-TC showed significant improvement in anxiety levels after the intervention in the intervention group (p = 0.048, ϕ = 0.344, p = 0.037). Conclusions: Our findings suggest a plausible anti-anxiety effect of educational kinesiology in kindergarteners with special needs by elevating the oxytocin levels. Future studies are warranted to further confirm our findings with a larger sample.

Intranasal oxytocin affects the stress response to social isolation in sheep

Oxytocin (OT) is a neuropeptide hormone that modulates several social behaviors and can affect the anxiety and stress response. The aim of this study was to determine if administration of intranasal OT affects the stress response to social isolation in sheep. Twenty adult Merino ewes were assigned to two groups; 1) Control group (CG, n = 10), which received an intranasal administration of isotonic saline and 2) Oxytocin-treated group (OTG, n = 10), which received an intranasal administration of OT (24 IU) 40 min before the animals were placed in the social isolation test. During the social isolation test (10 min), the behavior of the sheep was recorded, and blood samples were obtained before and after the test for the determination of cortisol, glucose and serum proteins, and heart rate and surface temperature were recorded. The OTG ewes had a higher cortisol concentration (P = 0.04) after social isolation, tended to vocalize more (P = 0.06) during isolation, and tended to have lower globulin concentrations (P = 0.10) than the CG ewes. Contrary to what we expected, the administration of intranasal OT increased the stress response to social isolation in ewes, which was evidenced by endocrine (greater increase in cortisol concentration), physiological (a tendency to present lower concentration of globulins in blood) and behavioral (a tendency to vocalize more) indicators. This study suggests that the administration of intranasal OT increased the stress response to isolation possibly by strengthening the social bond among ewes.

A way forward for anxiolytic drug development: Testing candidate anxiolytics with anxiety-potentiated startle in healthy humans

This review introduces a research strategy that may radically transform the pursuit of new anxiolytics, via the use of human models of anxiety in healthy individuals. Despite enormous investments in developing novel pharmacological treatments for anxiety disorders, pharmacotherapy for these conditions remains suboptimal. Most candidate anxiolytics from animal studies fail in clinical trials. We propose an additional screening step to help select candidate anxiolytics before launching clinical trials. This intermediate step moves the evidence for the potential anxiolytic property of candidate drugs from animals to humans, using experimental models of anxiety in healthy individuals. Anxiety-potentiated startle is a robust translational model of anxiety. The review of its face, construct, and predictive validity as well as its psychometric properties in humans establishes it as a promising tool for anxiolytic drug development. In conclusion, human models of anxiety may stir a faster, more efficient path for the development of clinically effective anxiolytics.

Oxytocin Differentially Modulates Amygdala Responses during Top-Down and Bottom-Up Aversive Anticipation

The ability to successfully regulate negative emotions such as fear and anxiety is vital for mental health. Intranasal administration of the neuropeptide oxytocin (OXT) has been shown to reduce amygdala activity but to increase amygdala-prefrontal cortex connectivity during exposure to threatening stimuli suggesting that it may act as an important modulator of emotion regulation. The present randomized, between-subject, placebo-controlled pharmacological study combines the intranasal administration of OXT with functional magnetic resonance imaging (fMRI) during an explicit emotion regulation paradigm in 65 healthy male participants to investigate the modulatory effects of OXT on both bottom-up and top-down emotion regulation. OXT attenuates the activation in the posterior insular cortex and amygdala during anticipation of top-down regulation of predictable threat stimuli in participants with high trait anxiety. In contrast, OXT enhances amygdala activity during the bottom-up anticipation of unpredictable threat stimuli in participants with low trait anxiety. OXT may facilitate top-down goal-directed attention by attenuating amygdala activity in high anxiety individuals, while promoting bottom-up attention/vigilance to unexpected threats by enhancing amygdala activity in low anxiety individuals. OXT may thus have the potential to promote an adaptive balance between bottom-up and top-down attention systems depending on an individual's trait anxiety level.

Divergent pathways mediate 5-HT1A receptor agonist effects on close social interaction, grooming and aggressive behaviour in mice: Exploring the involvement of the oxytocin and vasopressin systems

BACKGROUND

5-HT_1A receptor (5-HT_1AR) abnormalities are implicated in aggression, and there has been considerable interest in developing 5-HT_1AR agonists for treating aggression. Endogenous oxytocin (OXT) released upon stimulation of 5-HT_1ARs in the hypothalamus mediates at least some of the effects of 5-HT_1AR agonists on social behaviour.

AIMS

Given 5-HT_1AR, OXT receptor (OXTR) and vasopressin V1a receptor (V1aR) agonists can all reduce aggression, the current study aimed to determine whether the anti-aggressive effects of 5-HT_1AR stimulation can also be explained by downstream actions at OXTRs and/or V1aRs in a mouse model of non-territorial, hyper-aggressive behaviour.

METHODS

Male Swiss mice (N=80) were socially isolated or group housed for six weeks prior to the start of testing. Testing involved placing two unfamiliar weight- and condition-matched mice together in a neutral context for 10 minutes.

RESULTS

Social isolation led to a pronounced increase in aggressive behaviour, which was dose-dependently inhibited by the 5-HT_1AR agonist 8-OH-DPAT (0.1, 0.3 and 1 mg/kg intraperitoneally (i.p.)), with accompanying increases in close social contact (huddling) and grooming. The effects of 8-OH-DPAT on aggression, huddling and grooming were blocked by pretreatment with a selective 5-HT_1AR antagonist (WAY-100635; 0.1 mg/kg i.p.). The anti-aggressive effects of 8-OH-DPAT were unaffected by an OXTR antagonist (L-368,899; 10 mg/kg i.p.), whereas the effects on huddling and grooming were inhibited. Pretreatment with a V1aR antagonist (SR49059; 20 mg/kg i.p.) had no effect.

CONCLUSIONS

Our study suggests that stimulation of endogenous oxytocin is involved in the effects of 5-HT_1AR activation on close social contact and grooming but not aggression.

Serotonin mediates the panicolytic-like effect of oxytocin in the dorsal periaqueductal gray

INTRODUCTION AND OBJECTIVES

Oxytocin (OT) has been widely linked to positive social interactions, and there is great interest in OT as a therapy for a variety of neuropsychiatric conditions. Recent evidence also suggests that OT can play an important role in the mediation of anxiety-associated defensive responses, including a role for serotonin (5-HT) neurotransmission in this action. However, it is presently unknown whether OT additionally regulates the expression of panic-related behaviors, such as escape, by acting in the dorsal periaqueductal gray (dPAG), a key panic-regulating area. This study aimed to investigate the consequence of OT injection in the dPAG on escape expression and whether facilitation of 5-HT neurotransmission in this midbrain area is implicated in this action.

METHODS

Male Wistar rats were injected with OT in the dPAG and tested for escape expression in the elevated T-maze (ETM) and dPAG electrical stimulation tests. Using the latter test, OT's effect was also investigated after previous intra-dPAG injection of the OT receptor antagonist atosiban, the preferential antagonists of 5-HT_1A and 5-HT_2A receptors, WAY-100635 and ketanserin, respectively, or systemic pretreatment with the 5-HT synthesis inhibitor p-CPA.

RESULTS

OT impaired escape expression in the two tests used, suggesting a panicolytic-like effect. In the ETM, the peptide also facilitated inhibitory avoidance acquisition, indicating an anxiogenic effect. Previous administration of atosiban, WAY-100635, ketanserin, or p-CPA counteracted OT's anti-escape effect.

CONCLUSIONS

OT and 5-HT in the dPAG interact in the regulation of panic- and anxiety-related defensive responses. These findings open new perspectives for the development of novel therapeutic strategies for the treatment of anxiety disorders.

Making Sense of Computational Psychiatry

In psychiatry we often speak of constructing "models." Here we try to make sense of what such a claim might mean, starting with the most fundamental question: "What is (and isn't) a model?" We then discuss, in a concrete measurable sense, what it means for a model to be useful. In so doing, we first identify the added value that a computational model can provide in the context of accuracy and power. We then present limitations of standard statistical methods and provide suggestions for how we can expand the explanatory power of our analyses by reconceptualizing statistical models as dynamical systems. Finally, we address the problem of model building-suggesting ways in which computational psychiatry can escape the potential for cognitive biases imposed by classical hypothesis-driven research, exploiting deep systems-level information contained within neuroimaging data to advance our understanding of psychiatric neuroscience.

Effects of oxytocin administration on salivary sex hormone levels in autistic and neurotypical women

Background

Oxytocin administration, which may be of therapeutic value for individuals with social difficulties, is likely to affect endogenous levels of other socially relevant hormones. However, to date, the effects of oxytocin administration on endogenous hormones have only been examined in neurotypical individuals. The need to consider multi-hormone interactions is particularly warranted in oxytocin trials for autism due to evidence of irregularities in both oxytocin and sex steroid systems.

Methods

In this double-blind cross-over study, saliva samples were collected from 16 autistic and 29 neurotypical women before and after intranasal administration of 24 IU oxytocin or placebo. Oestradiol, testosterone, and oxytocin levels were quantified in saliva samples. Participants also completed the Autism-Spectrum Quotient (AQ) and Empathy Quotient (EQ) questionnaires.

Results

Distinct patterns of change in testosterone and oestradiol levels pre- to-post-administration were observed in autistic relative to neurotypical women (ANCOVA, p < 0.05 main effect of Group), controlling for sample collection time. The mean percent change oestradiol was + 8.8% for the autism group and − 13.0% for the neurotypical group (t = 1.81, p = 0.08), while the mean percent change testosterone was + 1.1% in the autism group and − 12.6% in the neurotypical group (t = 1.26, p = 0.22). In the oxytocin condition, the mean percent change oestradiol was + 12.6% in the autism group and − 6.9% in the neurotypical group (t = 1.78, p = 0.08), while the mean percent change testosterone was + 14.4% in the autism group and − 15.2% in the neurotypical group (t = 3.00, p = 0.006). Robust regression confirmed that group differences in percent change hormone levels were not driven by a small number of influential individuals. Baseline hormone levels did not differ between groups when considered individually. However, baseline testosterone relative to oestradiol (T:E2 ratio) was higher in autistic women (p = 0.023, Cohen’s d = 0.63), and this ratio correlated positively and negatively with AQ and EQ scores, respectively, in the combined sample.

Limitations

Further studies with larger and more diverse autistic sample are warranted to confirm these effects.

Conclusions

This study provides the first evidence that oxytocin influences endogenous testosterone levels in autistic individuals, with autistic women showing increases similar to previous reports of neurotypical men. These findings highlight the need to consider sex steroid hormones as a variable in future oxytocin trials.

Effects of chronic intranasal oxytocin on behavior and cerebral glucose uptake in juvenile titi monkeys

Intranasal oxytocin (IN OXT) has been proposed as a treatment for autism spectrum disorder (ASD); however, little is known about the effects of long-term exposure. This is the first study in a non-human primate species to examine how developmental exposure to chronic IN OXT affects juvenile's interactions with family members, social preference for parents versus strangers, anxiety-like behavior, and cerebral glucose metabolism. Titi monkeys are socially monogamous and biparental; their family bonds share important characteristics with human family bonds. Fourteen males and 15 females were treated intranasally with saline (n = 14) or 0.8 IU/kg OXT (n = 15), daily from 12 to 18 months of age. Compared to SAL-treated animals, OXT-treated animals of both sexes spent significantly more time grooming other family members (F₁ = 8.97, p = 0.006). Overall, OXT-treated subjects were more social (F₁ = 8.35, p = 0.005) during preference tests. OXT-treated females displayed an enhanced preference for their parents (t = 2.265, p = 0.026). OXT-treated males had a blunted preference for their parents and an increase in the time spent near unfamiliar pairs (F1 = 10.89, p = 0.001). During anxiety tests, OXT-treated males refused to complete the task more often than SAL-treated males and had longer latencies (p < 0.0001). Neuroimaging studies revealed that OXT-treated animals had higher glucose uptake across the social salience network as a whole after one month of treatment (F_1,9 = 1.07, p = 0.042). Our results suggest moderate prosocial effects of chronic IN OXT, that did not depend on anxiolytic properties. We also found important sex differences that should be considered in a translational context.

The involvement of oxytocin in the effects of chronic social defeat stress on emotional behaviours in adult female mandarin voles

Chronic social defeat stress (CSDS) can induce anxiety and depression in male rodents, but the prevalence of anxiety and depression is much higher in females, and effects of CSDS on adult females and its underlying mechanism remain unclear. Oxytocin is a stress-buffering hormone in the brain that modulates the physiological effects of stress. Strikingly, research regarding the effect of oxytocin on emotional changes caused by CSDS is still lacking in females. Thus, we focused on the involvement of the oxytocin system in changes in emotional regulation induced by CSDS in female voles. Seventy-day-old female mandarin voles (Microtus mandarinus) were exposed to aggressive adult females for 14 days, and the effects of CSDS on emotion and regulation of oxytocin system were characterized. In addition, we injected vehicle, oxytocin and oxytocin receptor antagonist into the nucleus accumbens (Nacc) of female voles to investigate the involvement of Nacc oxytocin in the effect of CSDS on emotion. Herein, we reported that CSDS increased anxiety and depression-like behaviour and the circulating level of corticosterone, but decreased the number of oxytocin projections and the protein and mRNA expression levels of oxytocin receptor in the Nacc. Injection of oxytocin into the Nacc reversed the effects of CSDS on anxiety-like and depressive-like behaviour, whereas combined injections of oxytocin and oxytocin receptor antagonist eliminated these effects. In conclusion, CSDS increases the levels of anxiety and depression possibly via a reduction in oxytocin projections and the oxytocin receptor level in the Nacc. Nacc oxytocin may be involved in the effects of CSDS on emotional behaviours.

Intranasal oxytocin enhances stress-protective effects of social support in women with negative childhood experiences during a virtual Trier Social Stress Test

Oxytocin is considered a biological mechanism underlying stress-protective effects of positive social interactions. It is assumed to underlie the women-specific tend-and-befriend response to stress, although few studies have tested this assertion with female samples. The aim of the present study was, therefore, to test whether oxytocin enhances stress-protective effects of social support during stress in women, taking into account the moderating role of childhood adversity. The sample consisted of 180 female undergraduate students who had reported on experiences of childhood abuse and how often their mother used love withdrawal as an insensitive disciplinary strategy. Women participated in a virtual version of the Trier Social Stress Test (TSST) and were randomly assigned to receive 24 IU oxytocin or a placebo and to receive support or no support from a female friend (sub-groups N = 45). Results showed that oxytocin reduced heart rate variability during the TSST in participants who received support, possibly indicating that oxytocin increases attention and stimulates a challenge motivational state in the presence of a friend. In addition, we found that, in the presence of a friend, oxytocin reduced state anxiety levels and cortisol levels after the TSST, but only in women with higher levels of adverse childhood experiences. Our findings may indicate that oxytocin is a neurobiological means to attain and benefit from social support under stressful circumstances, which may be particularly adaptive for women with a history of adversity. Thus, oxytocin may function as motivator for affiliative disposition during stress exposure in women with a history of childhood adversity. Results should be replicated in clinical samples.

Oxytocin Ameliorates Impaired Behaviors of High Fat Diet-Induced Obese Mice

Excessive intake of fat is a major risk factor for lifestyle-related diseases such as heart disease and also affects brain function such as object recognition memory, social recognition, anxiety behavior, and depression-like behavior. Although oxytocin (OXT) has been reported to improve object recognition, social recognition, anxiety behavior, and depression-like behavior in specific conditions, previous studies did not explore the impact of OXT in high-fat diet (HFD)-fed mice. Furthermore, it remains unclear whether intake of HFD affects OXT/oxytocin receptor (OXTR) in the brain. Here, we demonstrated that peripheral OXT administration improves not only social recognition but also object recognition and depressive-like behavior in HFD-fed mice. In contrast, peripheral OXT administration to HFD-fed male mice increased fear and anxiety-related behavior. In addition, we observed that intake of HFD decreased OXTR and c-fos mRNA expression in the hippocampus, specifically. Furthermore, peripheral OXT administration increased OXT mRNA expression in the hypothalamus. Altogether, these findings suggest that OXT has the potential to improve various recognition memory processes via peripheral administration but also has side effects that increase fear-related behavior in males.

Anxiolytic and Anxiogenic? How the Transcription Factor MEF2 Might Explain the Manifold Behavioral Effects of Oxytocin

The neuromodulator oxytocin, since its first synthesis by du Vigneaud in 1953, has mainly been associated with beneficial physiological effects, as well as positive social and emotional behaviors. This overall positive picture of oxytocin as the "love-, cuddle-, or bonding-hormone" has repeatedly been challenged since then. Oxytocin-induced effects that would be perceived as negative by the individual, such as increased anxiety or potentiation of stress-induced ACTH release, as well as the regulation of negative approach-related emotions, such as envy and schadenfreude (gloating) have been described. The general consent is that oxytocin, instead of acting unidirectional, induces changes in the salience network to shift the emphasis of emotional contexts, and therefore can, e.g., produce both anxiolytic as well as anxiogenic behavioral outcomes. However, the underlying mechanisms leading to alterations in the salience network are still unclear. With the aim to understand the manifold effects of oxytocin on a cellular/molecular level, a set of oxytocin receptor-coupled signaling cascades and downstream effectors regulating transcription and translation has been identified. Those oxytocin-driven effectors, such as MEF2 and CREB, are known modulators of the neuronal and glial cytoarchitecture. We hypothesize that, by determining cellular morphology and connectivity, MEF2 is one of the key factors that might contribute to the diverse behavioral effects of oxytocin.

Martial arts increase oxytocin production

Numerous studies have demonstrated that oxytocin (OT), a peptide hormone, plays an important role in regulating mammalian social behaviors, linking it to social affiliation in parent-infant attachment, romantic and filial relationships, and other prosocial behaviors, such as trust and cooperation. Not surprisingly, research efforts have been made to increase endogenous levels of OT. In the present study, we investigated whether traditional martial arts training, which integrates the natural benefits of physical exercise with dyadic prosocial interaction, would result in OT response. To this end, 68 beginner and advanced participants were recruited from several schools practicing Jujitsu ("soft art"), a form of traditional martial arts originating in Japan. Salivary OT levels were assessed at baseline, immediately following high-intensity training, and following a cool-down period. Analyses revealed a significant increase in OT immediately after a high-intensity training, returning to baseline levels following a cool-down period. Additionally, although no significant difference between beginner and advanced martial artists was found, a significantly higher increase in salivary OT followed ground grappling, as compared to "punch-kick" sparring, indicating an added benefit of close contact tactile interaction. These results suggest that the reportedly socially beneficial effects of traditional martial arts may be in part mediated by OT release and underscore the potentially therapeutic applications of these methods for disorders involving social dysfunction, such as autism, conduct problems, or schizophrenia.

Zebrafish oxytocin neurons drive nocifensive behavior via brainstem premotor targets

Animals have evolved specialized neural circuits to defend themselves from pain- and injury-causing stimuli. Using a combination of optical, behavioral and genetic approaches in the larval zebrafish, we describe a novel role for hypothalamic oxytocin (OXT) neurons in the processing of noxious stimuli. In vivo imaging revealed that a large and distributed fraction of zebrafish OXT neurons respond strongly to noxious inputs, including the activation of damage-sensing TRPA1 receptors. OXT population activity reflects the sensorimotor transformation of the noxious stimulus, with some neurons encoding sensory information and others correlating more strongly with large-angle swims. Notably, OXT neuron activation is sufficient to generate this defensive behavior via the recruitment of brainstem premotor targets, whereas ablation of OXT neurons or loss of the peptide attenuates behavioral responses to TRPA1 activation. These data highlight a crucial role for OXT neurons in the generation of appropriate defensive responses to noxious input.

Sex differences in fear extinction

Despite the exponential increase in fear research during the last years, few studies have included female subjects in their design. The need to include females arises from the knowledge gap of mechanistic processes underlying the behavioral and neural differences observed in fear extinction. Moreover, the exact contribution of sex and hormones in relation to learning and behavior is still largely unknown. Insights from this field could be beneficial as fear-related disorders are twice as prevalent in women compared to men. Here, we review an up-to-date summary of animal and human studies in adulthood that report sex differences in fear extinction from a structural and functional approach. Furthermore, we describe how these factors could contribute to the observed sex differences in fear extinction during normal and pathological conditions.

Cortisol and oxytocin show independent activity during chimpanzee intergroup conflict

The oxytocinergic system is involved in a range of functions, from attachment and social bonding to aggression and stress responses. Whether oxytocin is released in response to a stressor, shows contradictory results across species and potential contexts-dependent differences. To avoid unintended contextual changes due to experimental procedures, we tested this question non-invasively in wild chimpanzees in an ecologically valid context. We collected endogenous hormonal measures during exposure to a known natural stressor, intergroup conflict. Specifically, we tested for potential synchronous activation patterns between urinary oxytocin and cortisol in male and female chimpanzees during stressor exposure. Oxytocinergic system reactivity during chimpanzee intergroup conflict has already been established in this study population. Thus, we first investigated urinary cortisol levels during border patrol and intergroup encounter days, in comparison to another potential stressor, hunting, and control days. We found higher urinary cortisol levels during intergroup encounter days compared with control and hunting days. We then compared secretion patterns of oxytocin and cortisol in relation to increased levels of out-group contact and hostility ('out-group risk') during intergroup conflict. We found that increased 'out-group risk' was associated with higher cortisol levels, especially when involving direct visual or physical contact with rival groups. Although urinary oxytocin levels were high across intergroup conflict contexts, increasing levels of out-group risk showed no significant variation. Taken together, results indicate independent secretion of oxytocin and cortisol during chimpanzee intergroup conflict, emphasizing that stressor exposure in this context is not the main trigger of oxytocin secretion.

Sexual dimorphism of oxytocin and vasopressin in social cognition and behavior

The neuropeptides oxytocin (OT) and vasopressin (VP) are hormones that are known to mediate social behavior and cognition, but their influence may be sex-dependent. This paper aims to provide a comprehensive review of the sex-related influence of OT and VP on social cognition, focusing on partner preference and sexual orientation, trust and relevant behaviors, memory modulation, and emotion regulation. Most studies have suggested that OT facilitates familiar-partner preference in both sexes, with females being more significant, increased trust in others, especially for male, enhanced memory in either sex, and reduced anxious emotion in males. However, VP-regulated social cognition has been less studied. Other relevant studies have indicated that VP facilitated familiar-partner preference, improved memory, induced empathy formation, increased positive-emotion recognition, and induced anxiety without any sex difference. However, there was a male preponderance among studies, and results were often too complex to draw firm conclusions. Clarifying the interplay between OT/VP and sex hormones in the regulation of social cognition is necessary for further applications.

Complementary Neural Circuits for Divergent Effects of Oxytocin: Social Approach Versus Social Anxiety

Oxytocin (OT) is widely known for promoting social interactions, but there is growing appreciation that it can sometimes induce avoidance of social contexts. The social salience hypothesis posed an innovative solution to these apparently opposing actions by proposing that OT enhances the salience of both positive and negative social interactions. The mesolimbic dopamine system was put forth as a likely system to evaluate social salience owing to its well-described role in motivation. Evidence from several sources supports the premise that OT acting within the nucleus accumbens and ventral tegmental area facilitates social reward and approach behavior. However, in aversive social contexts, additional pathways play critical roles in mediating the effects of OT. Recent data indicate that OT acts in the bed nucleus of the stria terminalis to induce avoidance of potentially dangerous social contexts. Here, we review evidence for neural circuits mediating the effects of OT in appetitive and aversive social contexts. Specifically, we propose that distinct but potentially overlapping circuits mediate OT-dependent social approach or social avoidance. We conclude that a broader and more inclusive consideration of neural circuits of social approach and avoidance is needed as the field continues to evaluate the potential of OT-based therapeutics.

Williams Syndrome, Human Self-Domestication, and Language Evolution

Language evolution resulted from changes in our biology, behavior, and culture. One source of these changes might be human self-domestication. Williams syndrome (WS) is a clinical condition with a clearly defined genetic basis which results in a distinctive behavioral and cognitive profile, including enhanced sociability. In this paper we show evidence that the WS phenotype can be satisfactorily construed as a hyper-domesticated human phenotype, plausibly resulting from the effect of the WS hemideletion on selected candidates for domestication and neural crest (NC) function. Specifically, we show that genes involved in animal domestication and NC development and function are significantly dysregulated in the blood of subjects with WS. We also discuss the consequences of this link between domestication and WS for our current understanding of language evolution.

Role of oxytocin in the control of stress and food intake

Oxytocin neurones in the hypothalamus are activated by stressful stimuli and food intake. The oxytocin receptor is located in various brain regions, including the sensory information-processing cerebral cortex; the cognitive information-processing prefrontal cortex; reward-related regions such as the ventral tegmental areas, nucleus accumbens and raphe nucleus; stress-related areas such as the amygdala, hippocampus, ventrolateral part of the ventromedial hypothalamus and ventrolateral periaqueductal gray; homeostasis-controlling hypothalamus; and the dorsal motor complex controlling intestinal functions. Oxytocin affects behavioural and neuroendocrine stress responses and terminates food intake by acting on the metabolic or nutritional homeostasis system, modulating emotional processing, reducing reward values of food intake, and facilitating sensory and cognitive processing via multiple brain regions. Oxytocin also plays a role in interactive actions between stress and food intake and contributes to adaptive active coping behaviours.

Social context effects on error-related brain activity are dependent on interpersonal and achievement-related traits

Brain correlates of performance monitoring, such as the Error-Related Negativity (ERN), are considerably influenced by situational factors. For instance, errors committed during social interaction typically elicit enhanced ERNs. While individual differences in ERN magnitude have been implicated in a wide variety of psychopathologies, it remains unclear how individual dispositions may interact with situational incentives to influence performance monitoring. Here, we analysed how interpersonal (Affiliation) and achievement-related (Agency) traits moderated the effects of interpersonal competition and interpersonal cooperation on the ERN. For this purpose, electroencephalography was collected from 78 participants while they performed a Flanker Task either in a competitive or in a cooperative social context (i.e., between-subjects design). We found that competition predicted enhanced error-related activity patterns compared to cooperation. Furthermore, participants who scored high in Affiliation elicited enhanced error-related activity. Conversely, high Agency scores were associated with reduced error-related activity, but this was only observed in the competitive context. These results indicate that the brain's response to error commission is not only sensitive to social incentives. Rather, the activity of the evaluative system that produces error signals appears to be crucially determined by the personal relevance of the incentives present in the context in which performance is evaluated.

Acute and long-lasting effects of oxytocin in cortico-limbic circuits: consequences for fear recall and extinction

The extinction of conditioned fear responses entrains the formation of safe new memories to decrease those behavioral responses. The knowledge in neuronal mechanisms of extinction is fundamental in the treatment of anxiety and fear disorders. Interestingly, the use of pharmacological compounds that reduce anxiety and fear has been shown as a potent co-adjuvant in extinction therapy. However, the efficiency and mechanisms by which pharmacological compounds promote extinction of fear memories remains still largely unknown and would benefit from a validation based on functional neuronal circuits, and the neurotransmitters that modulate them. From this perspective, oxytocin receptor signaling, which has been shown in cortical and limbic areas to modulate numerous functions (Eliava et al. Neuron 89(6):1291-1304, 2016), among them fear and anxiety circuits, and to enhance the salience of social stimuli (Stoop Neuron 76(1):142-59, 2012), may offer an interesting perspective. Experiments in animals and humans suggest that oxytocin could be a promising pharmacological agent at adjusting memory consolidation to boost fear extinction. Additionally, it is possible that long-term changes in endogenous oxytocin signaling can also play a role in reducing expression of fear at different brain targets. In this review, we summarize the effects reported for oxytocin in cortico-limbic circuits and on fear behavior that are of relevance for the modulation and potential extinction of fear memories.

Oxytocin and vasopressin increase male-directed threats and vocalizations in female macaques

In a previous study, we reported that intranasal delivery of both oxytocin (OT) and arginine vasopressin (AVP) to male macaques relaxes spontaneous social interactions, flattens the existing dominance hierarchy, and increases behavioral synchrony with other monkeys. Here we report that intranasal OT and AVP administration modulates the behaviors of female macaque monkeys, but in robustly different ways from males. Most notably, both neuropeptides increase threatening and vocalization behaviors of females when they encounter males, and these behaviors effectively increase the social status of females over males. While OT and AVP heighten the confrontational nature of intersexual encounters, both peptides relax interactions between females. Finally, as previously reported for males, treating an individual female monkey with OT or AVP significantly modulates the behavior of her non-treated partner. Together, these findings show that OT and AVP can either inhibit or promote aggression, depending on sex and behavioral context, and call for a more careful, systematic examination of the functions of these neuropeptides in both sexes, especially in the context of therapeutics for human social disorders.

Oxytocin prevents the increase of cocaine-related responses produced by social defeat

The neuropeptide oxytocin (OXT) plays a critical role in the regulation of social and emotional behaviors. OXT plays a role in stress response and in drug reward, but to date no studies have evaluated its implication in the long-lasting increase of the motivational effects of cocaine induced by repeated social defeat (RSD). During the social defeat procedure, 1 mg/kg of OXT was administered 30 min before each episode of RSD. Three weeks after the last defeat, the effects of cocaine on the conditioned place preference (CPP), locomotor sensitization and the self-administration (SA) paradigms were evaluated. The influence of OXT on the levels of BDNF in the prefrontal cortex (PFC), striatum and hippocampus was also measured. Our results confirm that raising the levels of OXT during social defeat stress can block the long-lasting effects of this type of stress. OXT counteracts the anxiety induced by social defeat and modifies BDNF levels in all the structures we have studied. Moreover, OXT prevents RSD-induced increases in the motivational effects of cocaine. Administration of OXT before each social defeat blocked the social defeat-induced increment in the conditioned rewarding effects of cocaine in the CPP, favored the extinction of cocaine-associated memories in both the CPP and SA, and decreased reinstatement of cocaine-seeking behavior in the SA. In conclusion, the long-lasting effects of RSD are counteracted by administering OXT prior to stress, and changes in BDNF expression may underlie these protective effects.

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

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

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

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

Exercise decreases defensive responses to unpredictable, but not predictable, threat

BACKGROUND

Research supports the anxiolytic effect of exercise, but the mechanism underlying this effect is unclear. This study examines the influence of exercise in healthy controls on two distinct defensive states implicated in anxiety disorders: fear, a phasic response to a predictable threat, and anxiety, a sustained response to an unpredictable threat.

METHODS

Thirty-four healthy volunteers (17 male, age M = 26.18, SD = 5.6) participated in sessions of exercise (biking at 60-70% of heart rate reserve) and control (biking at 10-20% of heart rate reserve) activity for 30 min, separated by 1 week. Threat responses were measured by eyeblink startle and assessed with the "Neutral-Predictable-Unpredictable threat test," which includes a neutral (N) and two threat conditions, one with predictable (P) and one with unpredictable (U) shock.

RESULTS

Results show that exercise versus control activity reduces startle potentiation during unpredictable threat (P = .031), but has no effect on startle potentiation during predictable threat (P = .609).

CONCLUSIONS

These results suggest that exercise reduces defensive response to unpredictable, but not predictable, threat, a dissociation that may help inform clinical indications for this behavioral intervention, as well as provide clues to its underlying neurobehavioral mechanisms.