Correlated Neural Activity and Encoding of Behavior across Brains of Socially Interacting Animals.

Social interactions involve complex decision-making tasks that are shaped by dynamic, mutual feedback between participants. An open question is whether and how emergent properties may arise across brains of socially interacting individuals to influence social decisions. By simultaneously performing microendoscopic calcium imaging in pairs of socially interacting mice, we find that animals exhibit interbrain correlations of neural activity in the prefrontal cortex that are dependent on ongoing social interaction. Activity synchrony arises from two neuronal populations that separately encode one's own behaviors and those of the social partner. Strikingly, interbrain correlations predict future social interactions as well as dominance relationships in a competitive context. Together, our study provides conclusive evidence for interbrain synchrony in rodents, uncovers how synchronization arises from activity at the single-cell level, and presents a role for interbrain neural activity coupling as a property of multi-animal systems in coordinating and sustaining social interactions between individuals.

Ca2+ imaging of self and other in medial prefrontal cortex during social dominance interactions in a tube test.

The study of social dominance interactions between animals offers a window onto the decision-making involved in establishing dominance hierarchies and an opportunity to examine changes in social behavior observed in certain neurogenetic disorders. Competitive social interactions, such as in the widely used tube test, reflect this decision-making. Previous studies have focused on the different patterns of behavior seen in the dominant and submissive animal, neural correlates of effortful behavior believed to mediate the outcome of such encounters, and interbrain correlations of neural activity. Using a rigorous mutual information criterion, we now report that neural responses recorded with endoscopic calcium imaging in the prelimbic zone of the medial prefrontal cortex show unique correlations to specific dominance-related behaviors. Interanimal analyses revealed cell/behavior correlations that are primarily with an animal's own behavior or with the other animal's behavior, or the coincident behavior of both animals (such as pushing by one and resisting by the other). The comparison of unique and coincident cells helps to disentangle cell firing that reflects an animal's own or the other's specific behavior from situations reflecting conjoint action. These correlates point to a more cognitive rather than a solely behavioral dimension of social interactions that needs to be considered in the design of neurobiological studies of social behavior. These could prove useful in studies of disorders affecting social recognition and social engagement, and the treatment of disorders of social interaction.

Comparative approaches in social network ecology.

Social systems vary enormously across the animal kingdom, with important implications for ecological and evolutionary processes such as infectious disease dynamics, anti-predator defence, and the evolution of cooperation. Comparing social network structures between species offers a promising route to help disentangle the ecological and evolutionary processes that shape this diversity. Comparative analyses of networks like these are challenging and have been used relatively little in ecology, but are becoming increasingly feasible as the number of empirical datasets expands. Here, we provide an overview of multispecies comparative social network studies in ecology and evolution. We identify a range of advancements that these studies have made and key challenges that they face, and we use these to guide methodological and empirical suggestions for future research. Overall, we hope to motivate wider publication and analysis of open social network datasets in animal ecology.

Adult Neurogenesis and the Initiation of Social Aggression in Male Mice.

The hippocampus is important for social behavior and exhibits unusual structural plasticity in the form of continued production of new granule neurons throughout adulthood, but it is unclear how adult neurogenesis contributes to social interactions. In the present study, we suppressed neurogenesis using a pharmacogenetic mouse model and examined social investigation and aggression in adult male mice to investigate the role of hippocampal adult-born neurons in the expression of aggressive behavior. In simultaneous choice tests with stimulus mice placed in corrals, mice with complete suppression of adult neurogenesis in adulthood (TK mice) exhibited normal social investigation behaviors, indicating that new neurons are not required for social interest, social memory, or detection of and response to social olfactory signals. However, mice with suppressed neurogenesis displayed decreased offensive and defensive aggression in a resident-intruder paradigm, and less resistance in a social dominance test, relative to neurogenesis-intact controls, when paired with weight and strain-matched (CD-1) mice. During aggression tests, TK mice were frequently attacked by the CD-1 intruder mice, which never occurred with WTs, and normal CD-1 male mice investigated TK mice less than controls when corralled in the social investigation test. Importantly, TK mice showed normal aggression toward prey (crickets) and smaller, nonaggressive (olfactory bulbectomized) C57BL/6J intruders, suggesting that mice lacking adult neurogenesis do not avoid aggressive social interactions if they are much larger than their opponent and will clearly win. Taken together, our findings show that adult hippocampal neurogenesis plays an important role in the instigation of intermale aggression, possibly by weighting a cost-benefit analysis against confrontation in cases where the outcome of the fight is not clear.

A female-biased gene expression signature of dominance in cooperatively breeding meerkats.

Dominance is a primary determinant of social dynamics and resource access in social animals. Recent studies show that dominance is also reflected in the gene regulatory profiles of peripheral immune cells. However, the strength and direction of this relationship differs across the species and sex combinations investigated, potentially due to variation in the predictors and energetic consequences of dominance status. Here, we investigated the association between social status and gene expression in the blood of wild meerkats (Suricata suricatta; n = 113 individuals), including in response to lipopolysaccharide, Gardiquimod (an agonist of TLR7, which detects single-stranded RNA in vivo) and glucocorticoid stimulation. Meerkats are cooperatively breeding social carnivores in which breeding females physically outcompete other females to suppress reproduction, resulting in high reproductive skew. They therefore present an opportunity to disentangle the effects of social dominance from those of sex per se. We identify a sex-specific signature of dominance, including 1045 differentially expressed genes in females but none in males. Dominant females exhibit elevated activity in innate immune pathways and a larger fold-change response to LPS challenge. Based on these results and a preliminary comparison to other mammals, we speculate that the gene regulatory signature of social status in the immune system depends on the determinants and energetic costs of social dominance, such that it is most pronounced in hierarchies where physical competition is important and reproductive skew is large. Such a pattern has the potential to mediate life history trade-offs between investment in reproduction versus somatic maintenance.

When and Why Antiegalitarianism Affects Resistance to Supporting Black-Owned Businesses.

Understanding how initiatives to support Black-owned businesses are received, and why, has important social and economic implications. To address this, we designed three experiments to investigate the role of antiegalitarian versus egalitarian ideologies among White American adults. In Study 1 (N = 199), antiegalitarianism (vs. egalitarianism) predicted viewing initiatives supporting a Black-owned business as less fair, but only when the business was competing with other (presumably White-owned) businesses. In Study 2 (N = 801), antiegalitarianism predicted applying survival-of-the-fittest market beliefs, particularly to Black-owned businesses. Antiegalitarianism also predicted viewing initiatives supporting Black-owned businesses as less fair than initiatives that targeted other (presumably White-owned) businesses, especially for tangible (vs. symbolic) support that directly impacts the success of a business. In Study 3 (N = 590), antiegalitarianism predicted rejecting a program investing in Black-owned businesses. These insights demonstrate how antiegalitarian ideology can have the effect of maintaining race-based inequality, hindering programs designed to reduce that inequality.

Attachment and Political Personality are Heritable and Distinct Systems, and Both Share Genetics with Interpersonal Trust and Altruism.

The attachment and caregiving domains maintain proximity and care-giving behavior between parents and offspring, in a way that has been argued to shape people's mental models of how relationships work, resulting in secure, anxious or avoidant interpersonal styles in adulthood. Several theorists have suggested that the attachment system is closely connected to orientations and behaviors in social and political domains, which should be grounded in the same set of familial experiences as are the different attachment styles. We use a sample of Norwegian twins (N = 1987) to assess the genetic and environmental relationship between attachment, trust, altruism, right-wing authoritarianism (RWA), and social dominance orientation (SDO). Results indicate no shared environmental overlap between attachment and ideology, nor even between the attachment styles or between the ideological traits, challenging conventional wisdom in developmental, social, and political psychology. Rather, evidence supports two functionally distinct systems, one for navigating intimate relationships (attachment) and one for navigating social hierarchies (RWA/SDO), with genetic overlap between traits within each system, and two distinct genetic linkages to trust and altruism. This is counter-posed to theoretical perspectives that link attachment, ideology, and interpersonal orientations through early relational experiences.

Activation of androgen receptor-expressing neurons in the posterior medial amygdala is associated with stress resistance in dominant male hamsters.

Social stress is a negative emotional experience that can increase fear and anxiety. Dominance status can alter the way individuals react to and cope with stressful events. The underlying neurobiology of how social dominance produces stress resistance remains elusive, although experience-dependent changes in androgen receptor (AR) expression is thought to play an essential role. Using a Syrian hamster (Mesocricetus auratus) model, we investigated whether dominant individuals activate more AR-expressing neurons in the posterior dorsal and posterior ventral regions of the medial amygdala (MePD, MePV), and display less social anxiety-like behavior following social defeat stress compared to subordinate counterparts. We allowed male hamsters to form and maintain a dyadic dominance relationship for 12 days, exposed them to social defeat stress, and then tested their approach-avoidance behavior using a social avoidance test. During social defeat stress, dominant subjects showed a longer latency to submit and greater c-Fos expression in AR+ cells in the MePD/MePV compared to subordinates. We found that social defeat exposure reduced the amount of time animals spent interacting with a novel conspecific 24 h later, although there was no effect of dominance status. The amount of social vigilance shown by dominants during social avoidance testing was positively correlated with c-Fos expression in AR+ cells in the MePV. These findings indicate that dominant hamsters show greater neural activity in AR+ cells in the MePV during social defeat compared to their subordinate counterparts, and this pattern of neural activity correlates with their proactive coping response. Consistent with the central role of androgens in experience-dependent changes in aggression, activation of AR+ cells in the MePD/MePV contributes to experience-dependent changes in stress-related behavior.

Socially induced plasticity of the posterior tuberculum and motor behavior in zebrafish (Danio rerio).

Social dominance is prevalent throughout the animal kingdom. It facilitates the stabilization of social relationships and allows animals to divide resources according to social rank. Zebrafish form stable dominance relationships that consist of dominants and subordinates. Although social-status-dependent differences in behavior must arise due to neural plasticity, mechanisms of how neural circuits are reconfigured to cope with social dominance are poorly described. Here, we describe how the posterior tuberculum nucleus (PT), which integrates sensory social information to modulate spinal motor circuits, is morphologically and functionally influenced by social status. We combined non-invasive behavioral monitoring of motor activity (startle escape and swim) and histological approaches to investigate how social dominance affects the morphological structure, axosomatic synaptic connectivity, and functional activity of the PT in relation to changes in motor behavior. We show that dopaminergic cell number significantly increases in dominants compared to subordinates, while PT synaptic interconnectivity, demonstrated with PSD-95 expression, is higher in subordinates compared to dominants. Secondly, these socially induced morphological differences emerge after one week of dominance formation and correlate with differences in cellular activities illustrated with higher phosphor-S6 ribosomal protein expression in dominants compared to subordinates. Thirdly, these morphological differences are reversible as the social environment evolves and correlates with adaptations in startle escape and swim behaviors. Our results provide new insights of the neural bases of social behavior that may be applicable to other social species with similar structural and functional organization.

How infants predict respect-based power.

Research has shown that infants represent legitimate leadership and predict continued obedience to authority, but which cues they use to do so remains unknown. Across eight pre-registered experiments varying the cue provided, we tested if Norwegian 21-month-olds (N=128) expected three protagonists to obey a character even in her absence. We assessed whether bowing for the character, receiving a tribute from or conferring a benefit to the protagonists, imposing a cost on them (forcefully taking a resource or hitting them), or relative physical size were used as cues to generate the expectation of continued obedience that marks legitimate leadership. Whereas bowing sufficed in generating such an expectation, we found positive Bayesian evidence that all the other cues did not. Norwegian infants unlikely have witnessed bowing in their everyday life. Hence, bowing/prostration as cue for continued obedience may form part of an early-developing capacity to represent leadership built by evolution.

Exploring neural correlates of social dominance: Insights from behavioral, resting- state EEG, and ERP indices.

Numerous studies have explored the concept of social dominance and its implications for leadership within the behavioral and cognitive sciences in recent years. The current study aims to address the gap regarding the neural correlates of social dominance by investigating the associations between psychological measures of social dominance and neural features among a sample of leaders. Thirty healthy male volunteers engaged in a monetary gambling task while their resting-state and task-based electroencephalography data were recorded. The results revealed a positive association between social dominance and resting-state beta oscillations in central electrodes. Furthermore, a negative association was observed between social dominance and task-based reaction time as well as the amplitude of the feedback-related negativity component of the event-related potentials during the gain, but not the loss condition. These findings suggest that social dominance is associated with enhanced reward processing which has implications for social and interpersonal interactions.

Femmephobia Is a Uniquely Powerful Predictor of Anti-Gay Behavior.

The current study explored a form of femmephobia (specifically, negative attitudes toward femininity in men) as a predictor of anti-gay behaviors among a sample of heterosexual men (N = 417). Additional predictor variables included hierarchical worldviews (i.e., social dominance orientation, right-wing authoritarianism, narcissism) and prejudicial attitudes (i.e., old-fashioned and modern homonegativity). Femmephobia emerged as a robust predictor, accounting for 23% of the variance in anti-gay behavior, surpassing the explanatory power (15%) of all other considered variables combined. Moreover, social dominance only predicted anti-gay behavior when femmephobia levels were high. Future research on discrimination and violence related to sexual identity and gender expression should incorporate femmephobia as a key predictive factor.

The Effect of Chronic Overcrowding on Social Behavior and Expression of Neuroinflammation-Associated Genes in Rats.

The effect of chronic overcrowding on the social behavior of adult male Wistar rats was studied. From postnatal day 30 (P30) to P180, the rats lived under standard (STND) or overcrowded (CRWD) conditions. Starting from P100, rat behavior was studied in the social preference and tube dominance tests, and aggressive behavior was investigated in the resident-intruder test. After decapitation of rats on P180, amygdala, dorsal hippocampus, ventromedial hypothalamus, and medial prefrontal cortex were collected and analyzed for expression of the IL-1ß, TNF, TGF-ß1, and IL-6 mRNAs by quantitative polymerase chain reaction. Compared to the STND group, rats from the CRWD group demonstrated shorter interaction time with a social object in the social preference test. They also had more wins in the tube test and initiated more attacks in the resident-intruder test. Expression of the IL1ß gene in the hippocampus and medial prefrontal cortex and of the TGFß1 gene in the hippocampus, amygdala, and prefrontal cortex was increased in the CRWD group. The stress induced by overcrowding increased social dominance and aggressiveness and decreased social motivation in rats. The changes in the social behavior of CRWD rats were accompanied by upregulation of expression of genes for the proinflammatory cytokine IL-1ß and the anti-inflammatory cytokine TGF-ß1 in a number of brain structures, which can be considered as manifestations of neuroinflammation and compensatory processes, respectively.

The genetic underpinnings of right-wing authoritarianism and social dominance orientation explain political attitudes beyond Big Five personality.

OBJECTIVE: Political attitudes are predicted by the key ideological variables of right-wing authoritarianism (RWA) and social dominance orientation (SDO), as well as some of the Big Five personality traits. Past research indicates that personality and ideological traits are correlated for genetic reasons. A question that has yet to be tested concerns whether the genetic variation underlying the ideological traits of RWA and SDO has distinct contributions to political attitudes, or if genetic variation in political attitudes is subsumed under the genetic variation underlying standard Big Five personality traits. METHOD: We use data from a sample of 1987 Norwegian twins to assess the genetic and environmental relationships between the Big Five personality traits, RWA, SDO, and their separate contributions to political policy attitudes. RESULTS: RWA and SDO exhibit very high genetic correlation (r = 0.78) with each other and some genetic overlap with the personality traits of openness and agreeableness. Importantly, they share a larger genetic substrate with political attitudes (e.g., deporting an ethnic minority) than do Big Five personality traits, a relationship that persists even when controlling for the genetic foundations underlying personality traits. CONCLUSION: Our results suggest that the genetic foundations of ideological traits and political attitudes are largely non-overlapping with the genetic foundations of Big Five personality traits.

Supporting social hierarchy is associated with White police officers' use of force.

Three studies translate social dominance theory to policing, testing the relationship between individual officers' endorsement of social hierarchies and their tendency to use force against residents. This article demonstrates a link between officer psychological factors and force. Because police are empowered to use force to maintain social order, and because White officers hold a dominant racial identity, we hypothesized social dominance orientation (SDO) would relate to force positively for White officers. For Black officers, we hypothesized a weak relationship between SDO and force, if any. To test these predictions, we examined the relationships between SDO and force using negative binomial regression models stratified by officer race. In an eastern city, SDO relates to force incidents positively for White officers and negatively for Black officers. In a southern city, SDO relates to force positively for White officers, and not significantly for Black officers. Stratified by race and rank, a second eastern city shows a marginally significant, positive SDO/force relationship for White patrol officers, and no significant SDO/force relationship for Black patrol officers. Finally, testing our hypotheses on a dataset pooled across these cities revealed a positive SDO/force relationship among White officers, and no significant SDO/force relationship among Black officers. These findings are consistent with our hypotheses and suggest a need to examine the role that maintaining social hierarchies plays in police behaviors. Future research must continue to investigate these relationships, especially with larger samples of non-White officers, and information about officers' patrol environments.

Association between victimization and perpetration of cyberhate: The moderating role of social dominance orientation.

INTRODUCTION: Expressions of cyberhate motivated by characteristics such as gender, ethnicity, and religious beliefs are now present and prevalent on social networks. Past research, both in online and offline contexts, has identified that, although there may be an overlap between victims and perpetrators of violence; this is not always the case. Nevertheless, the number of studies focused on variables that moderate the relation between victimization and perpetration is still low. The current study aims at analyzing the relation between cyberhate victimization and perpetration and the potential moderating role of social dominance on this relation. METHOD: During the 2019/2020 school year in Andalusia, Spain, a prospective longitudinal study was implemented. The study used a representative sample of 1498 adolescents enrolled in compulsory secondary education in the first wave (51.8% female; Mage = 13.58) and 1195 adolescents in the second wave (53.2% female; Mage = 14.04). Surveys administrated to adolescents were used for data collection. RESULTS: The findings revealed a positive correlation between cyberhate victimization and perpetration. They supported the notion that social dominance not only predicted the perpetration of cyberhate several months later, but also its moderating effect on the relation between cyberhate victimization and perpetration. Cyberhate victims who reported higher levels of social dominance were more likely to become perpetrators several months later. CONCLUSION: Results suggest the need to implement preventive programs considering the influence of social dominance. These strategies could promote social equality and help to interrupt the cycle in which victims can become perpetrators of cyberhate.

Direct and indirect effects of social dominance orientation on hate speech perpetration via empathy and moral disengagement among adolescents: A multilevel mediation model.

Although it is known that social dominance orientation directly affects hate speech perpetration, few studies have explored the mechanisms by which this effect takes place during adolescence. Based on the socio-cognitive theory of moral agency, we aimed to fill this gap in the literature by exploring the direct and indirect effects of social dominance orientation on hate speech perpetration in offline and online settings. The sample included seventh, eigth, and ninth graders (N = 3225) (51.2% girls, 37.2% with an immigrant background) from 36 Swiss and German schools who completed a survey about hate speech, social dominance orientation, empathy, and moral disengagement. A multilevel mediation path model revealed that social dominance orientation had a direct effect on offline and online hate speech perpetration. Moreover, social dominance also had indirect effects via low levels of empathy and high levels of moral disengagement. No gender differences were observed. Our findings are discussed regarding the potential contribution to preventing hate speech during adolescence.

Population variation in signaling behavior and contest outcome in the jacky dragon.

Being aggressive and by extension, dominant, is an important mechanism for determining access to resources such as mates or territories. While predictors of contest outcome and dominance are increasingly studied, we have a poor understanding of how they vary across populations. Here, I use the widely distributed Australian agamid lizard, the Jacky dragon (Amphibolurus muricatus), to quantify variation in features predicting contest outcome among males of different populations. I measured physical attributes, maximal physiological performance capacity (sprint speed, endurance, bite force) and visual displays during staged encounters. I found that morphology, performance capacity and the type and frequency of visual displays used during agonistic interactions varied significantly across populations. Contest winners from the Cann River State Forest population favored tail-flicks and push-up/body-rocks, while those from Royal National Park were more likely to chase and individuals from Yarratt State Forest performed more bite-lunges than other populations. The losers of contests also differed in their displays. Individuals from the Cann River population were dominant over the others based on behavioral attributes (i.e., aggressive visual displays, chases and bite-lunges). I suggest that population differences in signal form and function could have implications for range dynamics as populations come into contact in an era of rapid environmental change.

Increased paternal corticosterone exposure influences offspring behaviour and expression of urinary pheromones.

BACKGROUND: Studies have shown that paternal stress prior to conception can influence the innate behaviours of their offspring. The evolutionary impacts of such intergenerational effects are therefore of considerable interest. Our group previously showed in a model of daily stress that glucocorticoid treatment of adult male mouse breeders prior to conception leads to increased anxiety-related behaviours in male offspring. Here, we aimed to understand the transgenerational effects of paternal stress exposure on the social behaviour of progeny and its potential influence on reproductive success. RESULTS: We assessed social parameters including social reward, male attractiveness and social dominance, in the offspring (F1) and grand-offspring (F2). We report that paternal corticosterone treatment was associated with increased display of subordination towards other male mice. Those mice were unexpectedly more attractive to female mice while expressing reduced levels of the key rodent pheromone Darcin, contrary to its conventional role in driving female attraction. We investigated the epigenetic regulation of major urinary protein (Mup) expression by performing the first Oxford Nanopore direct methylation of sperm DNA in a mouse model of stress, but found no differences in Mup genes that could be attributed to corticosterone-treatment. Furthermore, no overt differences of the prefrontal cortex transcriptome were found in F1 offspring, implying that peripheral mechanisms are likely contributing to the phenotypic differences. Interestingly, no phenotypic differences were observed in the F2 grand-offspring. CONCLUSIONS: Overall, our findings highlight the potential of moderate paternal stress to affect intergenerational (mal)adaptive responses, informing future studies of adaptiveness in rodents, humans and other species.

The bidirectional relationship between peer relationships and bullying: Evidence from cross-lagged analyses among Chinese children.

BACKGROUND: In the digital age, bullying manifests in two distinct forms: traditional bullying and cyberbullying. Children's peer relationships are important predictors of bullying, and bullying in turn predicts peer relationships. However, few researchers have noted the bidirectional relationship between peer relationships and bullying. METHODS: The present study used a two-wave cross-lagged longitudinal design to fill this gap. The potential sex differences were also examined in this relationship. The sample consisted of 527 Chinese children aged 8 to 12 years (M = 9.69, SD = .96; 53.5% female). Participants completed peer nominations for peer acceptance, peer rejection and social dominance, as well as self-reports of traditional bullying and cyberbullying. RESULTS: Results showed that peer rejection at the first time point (T1) significantly and positively predicted traditional bullying perpetration, cyberbullying perpetration and cyberbullying victimization at the second time point (T2). Traditional bullying victimization at T1 significantly and negatively predicted peer acceptance and social dominance at T2. The results also revealed significant male and female differences. For instance, among boys, peer acceptance at T1 significantly and negatively predicted cyberbullying victimization at T2. In contrast, this relationship was not observed among girls. The present findings have important implications for understanding the cyclical relationship between peer relationships and bullying and providing practical guidance for improving peer relationships and reducing bullying.