Aggression In Social Interactions Research Articles

Excluded and ashamed: Shame proneness interacts with social exclusion and testosterone reactivity to predict behavioral aggression

Exclusion from social relationships is a painful experience that may threaten an individual’s status and dominance. The steroid hormone testosterone, which fluctuates rapidly in response to such threats, may be implicated in subsequent behavioral action (e.g., aggressive or prosocial responses) that aims to protect or enhance one’s status after exclusion. Past research, however, indicates that the link between acute changes in testosterone and behavior depend on context-relevant individual dispositions. In the context of social exclusion, an individual’s level of shame proneness—characterized by a tendency to experience shame and to react submissively—is theoretically relevant to the testosterone-induced aggression relationship but has yet to be examined empirically. Here, men (n = 167) were randomly assigned to be socially included or excluded in the virtual ball-tossing game, Cyberball, after which aggressive behavior was examined using the Point Subtraction Aggression Paradigm (PSAP). Testosterone reactivity was measured via salivary hormone samples collected pre- and post-game. Moderated multiple regression analyses were run to examine the extent to which testosterone reactivity and shame proneness moderated the effect of Cyberball condition on aggression. Results revealed a significant two-way interaction between Cyberball condition and testosterone reactivity, as well as a three-way interaction including shame proneness. For individuals low in shame proneness, exclusion was associated with higher post-cyberball aggression among those who experienced a rise in testosterone but was associated with lower post-cyberball aggression among those who experienced a decrease in testosterone. For individuals high in shame proneness, however, exclusion did not meaningfully affect aggressive responses, regardless of whether they experienced an increase or decrease in testosterone. These findings extend our understanding of the moderating roles of context and disposition on the neuroendocrinology of aggression in social interaction

Tryptophan Hydroxylase 2 Knockout Male Rats Exhibit a Strengthened Oxytocin System, Are Aggressive, and Are Less Anxious.

The central serotoninergic system is critical for stress responsivity and social behavior, and its dysregulations have been centrally implicated in virtually all neuropsychiatric disorders. Genetic serotonin depletion animal models could provide a tool to elucidate the causes and mechanisms of diseases and to develop new treatment approaches. Previously, mice lacking tryptophan hydroxylase 2 (Tph2) have been developed, showing altered behaviors and neurotransmission. However, the effect of congenital serotonin deficiency on emotional and social behavior in rats is still largely unknown, as are the underlying mechanisms. In this study, we used a Tph2 knockout (Tph2–/–) male rat model to study how the lack of serotonin in the rat brain affects anxiety-like and social behaviors. Since oxytocin is centrally implicated in these behaviors, we furthermore explored whether the effects of Tph2 knockout on behavior would relate to changes in the oxytocin system. We show that Tph2–/– rats display reduced anxiety-like behavior and a high level of aggression in social interactions. In addition, oxytocin receptor expression was increased in the infralimbic and prelimbic cortices, paraventricular nucleus, dorsal raphe nucleus, and some subregions of the hippocampus, which was paralleled by increased levels of oxytocin in the medial frontal cortex and paraventricular nucleus but not the dorsal raphe nucleus, central amygdala, and hippocampus. In conclusion, our study demonstrated reduced anxiety but exaggerated aggression in Tph2–/– male rats and reveals for the first time a potential involvement of altered oxytocin system function. Meanwhile, the research of oxytocin could be distinguished in almost any psychiatric disorder including anxiety and mental disorders. This research potentially proposes a new target for the treatment of such disorders, from a genetic serotonin deficiency aspect.

Postweaning Isolation Rearing Alters the Adult Social, Sexual Preference and Mating Behaviors of Male CD-1 Mice.

Objective: No study has comprehensively evaluated the effect of postweaning isolation on the social and sexual behaviors of a certain strain of rodents in ethology. The present study aims to explore how and to what extent isolation rearing after postweaning affects the social and sexual behaviors of male CD-1 mice in adulthood systematically.Methods: Male CD-1 mice were randomly assigned to two groups: isolation reared (IS, one mouse per cage, n = 30) and group housed (GH, five mice per cage, n = 15). The mice underwent isolation rearing from postnatal day 23 to day 93. Then, social affiliation, recognition and memory were measured through selection task experiments. Social interaction under a home cage and novel environment were measured via resident–intruder and social interaction test, respectively. Furthermore, sexual preference, homosexual and heterosexual behaviors were measured.Results: Our study found that postweaning isolation increased the social affiliation for conspecifics (p = 0.001), reduced social recognition (p = 0.042) and impaired social memory. As for social interaction, isolated mice showed a remarkably increased aggression toward the intruder male in a home cage or novelty environment. For instance, isolated mice presented a short attack latency (p < 0.001), high attack frequency (p < 0.001) and long attack duration (p < 0.001). In addition, isolated mice exhibited further social avoidance. Contrastingly, isolated mice displayed a reduced sexual preference for female (IS: 61.47 ± 13.80%, GH: 70.33 ± 10.06%, p = 0.038). As for heterosexual behavior, isolated mice have a short mating duration (p = 0.002), long mounting latency (p = 0.002), and long intromission latency (p = 0.015). However, no association was observed between postweaning isolation and homosexual behavior in male CD-1 mouse.Conclusion: Postweaning isolation increased the social affiliation, impaired the social cognition and considerably increased the aggression in social interaction of adult male CD-1 mice. Postweaning isolation induced a decreased sexual preference for female in adulthood. Postweaning isolation extended the latency to mate, thereby reducing mating behavior. No association was observed between isolation and homosexual behavior.

"We're not gonna be friends anymore": Associations between viewing relational aggression on television and relational aggression in text messaging during adolescence.

A number of studies suggest that adolescents who view relational aggression on television are more likely to engage in higher levels of subsequent relational aggression in social interactions. This study examined longitudinal associations between viewing relational aggression on television and relationally aggressive behavior in text messaging over a 1-year period during adolescence. Participants were 197 adolescents who completed a number of questionnaires regarding media use and aggression. Adolescents were each given a BlackBerry device and a sample of text messages was coded for aggressive behavior. Results revealed that exposure to relational aggression on television was associated with higher levels of relational aggression in texting one year later, but only for girls. Results are discussed with reference to the General Aggression Model.

A conceptual frame model for the analysis of aggression in social interactions.

Abstract Research on aggression focuses almost exclusively on the aggressive individual so that aggression is usually described as an individual-centered event. By contrast, the model presented in this article was developed through research of naturally occurring, aggressive interactions between adolescents in which the social and physical environment of aggressive events is a critical focus. The model provides a conceptual frame for the analysis of aggression in social interactions in natural settings that takes the complexity of social, environmental, and individual factors into account by distinguishing three systems (the biological, psychic, and social systems) and analyzing their interrelations and co-evolutionary processes. This article considers consequences for aggressive behavior when systems of different phylogenetic ages affect one another, and it delineates the interrelationships between systems and their environments and their mutual influence on one another. The model generated an innovative methodology for assessing aggression in natural settings and new technique, the use of camera-glasses for recording data of social interactions and environments from the aggressively reacting individual’s perspective.

Complex, multimodal behavioral profile of the Homer1 knockout mouse

Proteins of the Homer1 immediate early gene family have been associated with synaptogenesis and synaptic plasticity suggesting broad behavioral consequences of loss of function. This study examined the behavior of male Homer1 knockout (KO) mice compared with wild-type (WT) and heterozygous mice using a battery of 10 behavioral tests probing sensory, motor, social, emotional and learning/memory functions. KO mice showed mild somatic growth retardation, poor motor coordination, enhanced sensory reactivity and learning deficits. Heterozygous mice showed increased aggression in social interactions with conspecifics. The distribution of mGluR5 and N-methyl-D-aspartate receptors (NMDA) receptors appeared to be unaltered in the hippocampus (HIP) of Homer1 KO mice. The results indicate an extensive range of disrupted behaviors that should contribute to the understanding of the Homer1 gene in brain development and behavior.

Hawks, Doves, and Mixed-symmetry Games

The hawk–dove game has proved to be an important tool for understanding the role of aggression in social interactions. Here, the game is presented in a more general form (GHD) to facilitate analyses of interactions between individuals that may differ in “size”, where size is interpreted as a surrogate for resource holding power. Three different situations are considered, based on the availability and use of information that interacting individuals have about their sizes: the classical symmetric case, in which no information about sizes is used, the asymmetric case, in which the individuals know their relative sizes and thus their chances of prevailing in combat, and a mixed-symmetry case, in which each individual only knows its own size (or only knows its opponent's size). I describe and use some recently developed methods for multitype games—evolutionary games involving two or more categories of players. With these methods and others, the evolutionarily stable strategies (ESSs) that emerge for the three different cases are identified and compared. A proof of the form and uniqueness of the ESS for the mixed-symmetry case is presented. In this situation, one size category at most can play a mixed strategy; larger individuals are aggressive and smaller individuals are not. As the number of size categories approaches infinity and the size distribution becomes continuous, there is a threshold size, above which all individuals are aggressive, and below which they are not.

Effects of nutritional lithium deficiency on behavior in rats

To demonstrate whether nutritional lithium deficiency is associated with behavioral changes, male Sprague-Dawley rats were placed on a lithium-deficient diet (Li content < .01 ppm). A lithium-deprived group, receiving drinking water containing 31 microM NaCl, were compared to a control group receiving drinking water containing 31 microM LiCl. Growth and general appearance were the same in both groups. However, lithium-deficient animals demonstrated decreased aggression in social interactions with other rats and also in response to handling. The phase of wheel-running activity was delayed by 0.8 h and exhibited decreased amplitude (p < .05). Other behaviors, including acquisition and retention of a passive avoidance response, were unaffected by lithium deprivation.