The effects of environmental context on laboratory rat social recognition

The effects of environmental context on laboratory rat social recognitio

Integrating personality research and animal contest theory: aggressiveness in the green swordtail <i>Xiphophorus helleri</i>

&lt;p&gt;Aggression occurs when individuals compete over limiting resources. While theoretical studies have long placed a strong emphasis on context-specificity of aggression, there is increasing recognition that consistent behavioural differences exist among individuals, and that aggressiveness may be an important component of individual personality. Though empirical studies tend to focus on one aspect or the other, we suggest there is merit in modelling both within-and among-individual variation in agonistic behaviour simultaneously. Here, we demonstrate how this can be achieved using multivariate linear mixed effect models. Using data from repeated mirror trials and dyadic interactions of male green swordtails, &lt;i&gt;Xiphophorus helleri&lt;/i&gt;, we show repeatable components of (co)variation in a suite of agonistic behaviour that is broadly consistent with a major axis of variation in aggressiveness. We also show that observed focal behaviour is dependent on opponent effects, which can themselves be repeatable but were more generally found to be context specific. In particular, our models show that within-individual variation in agonistic behaviour is explained, at least in part, by the relative size of a live opponent as predicted by contest theory. Finally, we suggest several additional applications of the multivariate models demonstrated here. These include testing the recently queried functional equivalence of alternative experimental approaches, (e. g., mirror trials, dyadic interaction tests) for assaying individual aggressiveness.&lt;/p&gt

Recognition of conspecific odours by laboratory rats (Rattus norvegicus) does not show context specificity.

Recognition of conspecific odours by laboratory rats (Rattus norvegicus) does not show context specificity

Conflict between background matching and social signalling in a colour-changing freshwater fish

The ability to change coloration allows animals to modify their patterning to suit a specific function. Many freshwater fishes, for example, can appear cryptic by altering the dispersion of melanin pigment in the skin to match the visual background. However, melanin-based pigments are also used to signal dominance among competing males; thus colour change for background matching may conflict with colour change for social status signalling. We used a colour-changing freshwater fish to investigate whether colour change for background matching influenced aggressive interactions between rival males. Subordinate males that had recently darkened their skin for background matching received heightened aggression from dominant males, relative to males whose coloration had not changed. We then determined whether the social status of a rival male, the focal male's previous social status, and his previous skin coloration, affected a male's ability to change colour for background matching. Social status influenced skin darkening in the first social encounter, with dominant males darkening more than subordinate males, but there was no effect of social status on colour change in the second social encounter. We also found that the extent of skin colour change (by both dominant and subordinate males) was dependent on previous skin coloration, with dark males displaying a smaller change in coloration than pale males. Our findings suggest that skin darkening for background matching imposes a significant social cost on subordinate males in terms of increased aggression. We also suggest that the use of melanin-based signals during social encounters can impede subsequent changes in skin coloration for other functions, such as skin darkening for background matching

Sensory Contact Model: Protocol, Control, Applications

Among the models that become more and more popular in behavioral neuroscience are biosocial models, which allow studying the consequences of chronic social conflicts and social stress in animals. The sensory contact model appears to represent one of such models. Repeated experience of aggression or social defeats in daily agonistic interactions in male mice of different strains leads to the formation of opposing kinds of social behavior: one attributable to winners (aggressors) and another attributable to losers (defeated males, victims of aggression). A large variety of behavioral pathologies which develop in male mice in these conditions (anxious depression, catalepsy, social withdrawal, pronounced aggression, anxiety, hyperactivity, cognitive disturbances, anhedonia etc.), which are accompanied by somatic changes (reduced gonad function, psychogenic immune deficiency etc), suggest that this approach could be used for different aims of biomedical studies. Putative mechanisms of release and maintenance of aggressive and submissive behaviors in male mice under the sensory contact model, criteria of correct application, basic experimental setups and problem of the control, methodical capabilities and potentials of the sensory contact model applications are discussed in this paper

Music and Aggression: The Impact of Sexual-Aggressive Song Lyrics on Aggression-Related Thoughts, Emotions, and Behavior Toward the Same and the Opposite Sex

Three studies examined the impact of sexual-aggressive song lyrics on aggressive thoughts, emotions, and behavior toward the same and the opposite sex. In Study 1, the authors directly manipulated whether male or female participants listened to misogynous or neutral song lyrics and measured actual aggressive behavior. Male participants who were exposed to misogynous song lyrics administered more hot chili sauce to a female than to a male confederate. Study 2 shed some light on the underlying psychological processes: Male participants who heard misogynous song lyrics recalled more negative attributes of women and reported more feelings of vengeance than when they heard neutral song lyrics. In addition, men-hating song lyrics had a similar effect on aggression-related responses of female participants toward men. Finally, Study 3 replicated the findings of the previous two studies with an alternative measure of aggressive behavior as well as a more subtle measure of aggressive cognitions. The results are discussed in the framework of the General Aggression Model

Snca and Bdnf gene expression in the VTA and raphe nuclei of midbrain in chronically victorious and defeated male mice

The study aimed to analyze the mRNA levels of Snca and Bdnf genes in the ventral tegmental area (VTA) and raphe nuclei of the midbrain in male mice that had each won or defeated 20 encounters in daily agonistic interactions. Groups of animals that had the same winning and losing track record followed by a no-fight period for 14 days were also studied. Snca mRNA levels were increased in the raphe nuclei in the losers and in the VTA of the winners. After fighting deprivation Snca mRNA levels were decreased to the control level in both groups. Snca mRNA levels were similar to the control level in the VTA of the losers and in the raphe nuclei of the winners. However Snca gene expression was increased in these areas after no-fight period in the winners and losers in comparison with respective mRNA levels in the undeprived animals. Significant positive correlations were found between the mRNA levels of Snca and Bdnf genes in the raphe nuclei. It was concluded, that social experience affects Snca gene expression depending on brain areas and functional activity of monoaminergic systems in chronically victorious or defeated mice

Bullying Roles in Changing Contexts: The Stability of Victim and Bully Roles from Primary to Secondary School

The present study was conducted to predict bullying roles over a six years time period and across contexts differing in the degree of peer hierarchies. Out of two representative data sets from primary (N = 1525) and secondary school (N = 2958), 282 children (156 boys; 126 girls) were followed up longitudinally. Self reports on bullying experiences and peer reports about social status were assessed by a structured individual interview (in primary school) and by questionnaire given classwise (in secondary school). Risk analyses showed, that only a bully role in primary school yields a risk to be sustained in secondary school. However, victims in primary school classes with a more pronounced degree of hierarchical structuring proved stable in their role while the victim role was unstable from primary school classes with low hierarchical structuring. This interaction did not apply to bully role stability. Differential characteristics of the victim and the bully role in primary school and secondary school settings are discussed.Die vorliegende Untersuchung wurde durchgeführt, um Bullyingrollen über einen Zeitraum von sechs Jahren und Kontexte, die sich im Ausmaß der sozialen Strukturierung unterschieden, vorherzusagen. Auf der Grundlage von zwei repräsentativen Datensätzen aus der Grundschule (n= 1525) und der weiterführenden Schule (N= 2958) wurden dazu die Daten von 282 Kinder (156 Jungen, 126 Mädchen) längsschnittlich analysiert. Die Selbstberichte über Bullyingerfahrungen und Mitschülerberichte über den sozialen Status der Kinder wurden in der Grundschule durch ein strukturiertes Interview und in der weiterführenden Schule durch klassenweise Fragebogenerhebung erfasst. Riskikoanalysen zeigen, dass nur die Täterrolle in der Grundschule einen Risikofaktor für eine Täterrolle in der weiterführenden Schule darstellt. Eine Opferrolle war hingegen nur dann stabil, wenn die Opfer in Grundschulklassen mit schon ausgeprägten Dominanzstrukturen viktimisiert wurden, während aus Grundschulklassen mit geringer hierarchischer Strukturierung keine stabile Opferrolle vorhersagbar war. Dieses Interaktionmuster gilt nicht für die Stabilität der Täterrollen. Differentielle Charakteristika der Opferrolle und der Täterrolle in der Grundschule und der weiterführenden Schule werden diskutiert