The role of the frontal cortex of the left and right hemispheres in regulating the intraspecific interaction of rats with differing zoosocial experience

By means of the analysis of probabilistic ethological structures of the intraspecies rats behaviour in the test "stranger-resident" and by the method of isolated destruction of the frontal cortex or the left and right hemispheres,--it is established that the frontal cortex of the left hemisphere regulates the intraspecies sociability and keeps it on a certain level, because the change (increase) of the intraspecies sociability is observed only at the unilateral destruction of the left frontal cortex. Isolation from the relatives in early ontogenesis leads to the loss of regulating influence of the left frontal cortex on the intraspecies sociability. In isolated animals the frontal cortex of the left hemisphere regulates the level and probability of the appearance of aggression. The right hemisphere ensures the adequate inclusion of the aggression in the probabilistic ethological structure of the total intraspecies behaviour; at its damage the forms appear of an adequate pathological aggression, and connection is lost between the elements of aggressive behaviour and the acts of intraspecies sociability.     

Characteristics of the intraspecies interaction of rats with differing zoosocial experience

It has been found that among white outbred rats with different experience of intraspecies contact four types of reaction to the partner are singled out in the "stranger-resident" test: active, neutral passive, highly-aggressive. Belonging to one or another type is determined by the level and correlation of aggression and intraspecies sociability. Among animals isolated in an adult age, all four types of reaction to the partner are represented while in rats kept in isolation since 13--14th day of life only one type is presented--the active one. For animals of the control group the first three types of reaction are typical. It is revealed that only "late" isolation leads to a pathological increase of aggressivity in a part of the animals; an increase of aggression in "early" isolants may be considered as a consequence of sharp rise of intraspecies sociability. Conclusion is made about principal difference in mechanisms of aggression increase in "early" and "late" isolants.     

Diversifying and correlational selection on behavior toward conspecific and heterospecific competitors in brook stickleback (Culaea inconstans)

Behaviors toward heterospecifics and conspecifics may be correlated because of shared mechanisms of expression in both social contexts (nonadaptive covariation) or because correlational selection favors adaptive covariation. We evaluated these hypotheses by comparing behavior toward conspecifics and heterospecifics in brook stickleback (Culaea inconstans) from three populations sympatric with and three allopatric from a competitor, the ninespine stickleback (Pungitius pungitius). Behavioral traits were classified into three multivariate components: overt aggression, sociability, and activity. The correlation of behavior between social contexts for both overt aggression and activity varied among populations in a way unrelated to sympatry with ninespine stickleback, while mean aggression was reduced in sympatry. Correlations in allopatric populations suggest that overt aggression and activity may genetically covary between social contexts for nonadaptive reasons. Sociability was rarely correlated in allopatry but was consistently correlated in sympatry despite reduced mean sociability, suggesting that correlational selection may favor a sociability syndrome in brook stickleback when they coexist with ninespine stickleback. Thus, interspecific competition may impose diversifying selection on behavior among populations, although the causes of correlated behavior toward conspecifics and heterospecifics and whether it can evolve in one social context independent of the other may depend on the type of behavior.     

Interference with ritualized threat behaviour in Cichlasoma nigrofasciatum

According to ethological theory, ritualized threat behaviour functions to prevent overt aggression. This prediction was tested in twenty-three pairs of male Cichalasoma nigrofasciatum. Pairs prevented from giving frontal displays by surgically restrained gill covers showed significantly less mouth fighting than sham operates. Pairs prevented from giving frontals and impaired in delivering tail beats because of separated caudal-fin rays showed intermediate aggressive behaviour. Experimental animals in both groups fought and frequently became dominant when paired with sham operates. It was concluded that threat behaviour in C. nigrofasciatum increases subsequent aggressive behaviours both quantitatively and qualitatively. It is suggested that ethological theory has identified the effects of ritualized aggression as a complex behavioural sequence ending in submissive behaviour with that of its first phase alone.     

Differences between playfighting and serious fighting among Zapotec children

Patterns of fighting and playfighting were observed among Zapotec-speaking children of Oaxaca, Mexico, as part of an ethological field study. Focal and incident sampling techniques were employed to record the behavior of 3–8 years olds. It was found that real fighting could be distinguished from playfighting on the basis of facial and vocal intention signals displayed by the children of this age group. These two classes of behavior differed in a number of ways, including rate of occurrence, mean duration of episodes, variability of constituent actions, frequency of wrestling and chase-flee behaviors, level of restraint, number of partners, and reactions of nonparticipating children. The findings are discussed in relation to information on fighting and playfighting from other studies of human children. Limited phylogenetic comparison are also made. It is suggested that in studies of human children, play aggression should not be lumped together with real aggression, as is sometimes done, because these are motivationally distinct types of behavior.     

Effect of unilateral spreading cortical depression on intraspecies aggression and sociability of isolated mice

It has been shown that aggressive forms of behaviour are controlled preferentially by the left hemisphere and sociability by the right one. Consequently, the opposite poles of the continuum "aggression-sociability" have different lateralization. Interconnection between functional interhemispheric asymmetry and aggression degree has been revealed: in high-aggressive mice the differences in the effect of left and right hemispheres inactivation are expressed stronger as compared to low-aggressive and nonaggressive animals.     

The integration of dominance and social bonding in primates

Social dominance is usually viewed from the perspective of intragroup competition over access to limited resources. The present paper, while not denying the importance of such competition, discusses the dominance concept among monkeys and apes in the context of affiliative bonding, social tolerance, and the reconciliation of aggressive conflicts. Two basic proximate mechanisms are supposed to provide a link between dominance and interindividual affiliation, namely, formalization of the dominance relationship (i.e., unequivocal communication of status), and conditional reassurance (i.e., the linkage of friendly coexistence to formalization of the relationship). Ritualized submission is imposed upon losers of dominance struggles by winners; losers are offered a "choice" between continued hostility or a tolerant relationship with a clearly signalled difference in status. If these two social mechanisms are lacking, aggression is bound to have dispersive effects. In their presence, aggression becomes a well-integrated, even constructive component of social life. In some higher primates this process of integration has reached the stage where status differences are strongly attenuated. In these species, sharing and trading can take the place of overt competition. The views underlying this "reconciled hierarchy" model are only partly new, as is evident from a review of the ethological literature. Many points are illustrated with data on a large semi-captive colony of chimpanzees (Pan troglodytes), particularly data related to striving for status, reconciliation behavior, and general association patterns. These observations demonstrate that relationships among adult male chimpanzees cannot be described in terms of a dichotomy between affiliative and antagonistic tendencies. Male bonding in this species has not been achieved by an elimination of aggression, but by a set of powerful buffering mechanisms that mitigate its effects. Although female chimpanzees do exhibit a potential for bonding under noncompetitive conditions, they appear to lack the buffering mechanisms of the males.     

A field study of emotions,dominance, and social behavior in a group of baboons (Papio anubis)

This study involved the testing of a new rating instrument designed to measure emotional behavior, and the examination of the correlations between dominance and certain classes of emotional behavior. The sample population was a troop of 7 olive baboons. The rating scale was found to be very effective. Wide individual differences in scores on the 8 dimensions of the scale were detected. Also, there was high interjudge reliability indicating that independent observers can agree on the temperamental characteristics of primates. Mean time being groomed, a duration/frequency ratio, more fully reflects the dominance relationship between two animals than any other single index. Mean time being groomed was found to correlate significantly with the dimensionsprotection, deprivation, rejection anddestruction. More dominant animals showed less sociability and more aggression than the submissive animals, who showed a great deal of both sociability and fearfulness.     

Influences of alcohol on the social responses of male resident mice to anosmic female intruders

The effects of acutely administered ethanol (0, 0.5, 1.0 or 2.0 g/kg, i.p.) were studied in individually-housed male Swiss mice in dyadic encounters with anosmic, group-housed female intruders. The procedure was designed to suppress levels of attack in isolates. Videotape analysis of 500-second encounters, using both simplified and complex ethological techniques, revealed that alcohol did not potentiate aggression at any dose tested. At the highest alcohol dose there were marked increases in total time spent in timid-defensive and non-social behaviours, with concomitant decreases in aggressive and social/sexual activities. The postural analysis showed increases and decreases in elements of non-social behaviour and social investigatory elements, together with marked increases in certain timid-defensive activities and a decrease in tail-rattling. Comparison with previous work on inter-male paradigms shows that the type of opponent not only modifies the behaviour of saline-treated controls, but markedly influences the behavioural responses to alcohol treatment.     

A multi-trait,field-based examination of personality in a semi-aquatic turtle

Studies documenting and quantifying personality traits are common in animal behavior. Such studies often consider the nature of individual variation and personality as correlated with a variety of natural history, physiological, or ecological traits, and therefore consider the importance of personality for strategies in wild systems. Though such studies have contributed markedly to our understanding of the important aspects of personality that may covary with a variety of factors that might affect fitness, much of the research on animal personalities is taxonomically limited. To supplement and compliment the laboratory study of reptile personality, we examined the patterns of multiple personality traits in wild Eastern painted turtles (Chrysemys picta) in the field. We examined patterns of aggression, sociability, and boldness across these traits in different contexts in 103 adult, wild-caught turtles. We found strong correlations both within and among the focal behavioral axes, representing robust evidence for personality in this species. Specifically, we found strong relationships among many measures of aggression, as well as relationships between aggression and our measures of boldness. Finally, we note a tendency for sociability in our turtles, with animals scoring high on sociability showing lower tendency toward aggression. Overall, our study provides robust evidence for correlated suites of behavioral traits, or personality, in a semi-aquatic turtle surveyed in the wild. Future work should continue to expand the range of traits examined to more fully consider the ecological consequences of variation in personality in this and similar species.     

Quantitative trait locus mapping and analysis of heritable variation in affiliative social behavior and co‐occurring traits

Humans exhibit broad heterogeneity in affiliative social behavior. Twin and family studies show that individual differences in core dimensions of social behavior are heritable, yet there are knowledge gaps in understanding the underlying genetic and neurobiological mechanisms. Animal genetic reference panels (GRPs) provide a tractable strategy for examining the behavioral and genetic architecture of complex traits. Here, using males from 50 mouse strains from the BXD GRP, 4 domains of affiliative social behavior—social approach, social recognition, direct social interaction (DSI) (partner sniffing) and vocal communication—were examined in 2 widely used behavioral tasks—the 3‐chamber and DSI tasks. There was continuous and broad variation in social and nonsocial traits, with moderate to high heritability of social approach sniff preference (0.31), ultrasonic vocalization (USV) count (0.39), partner sniffing (0.51), locomotor activity (0.54‐0.66) and anxiety‐like behavior (0.36). Principal component analysis shows that variation in social and nonsocial traits are attributable to 5 independent factors. Genome‐wide mapping identified significant quantitative trait loci for USV count on chromosome (Chr) 18 and locomotor activity on Chr X, with suggestive loci and candidate quantitative trait genes identified for all traits with one notable exception—partner sniffing in the DSI task. The results show heritable variation in sociability, which is independent of variation in activity and anxiety‐like traits. In addition, a highly heritable and ethological domain of affiliative sociability—partner sniffing—appears highly polygenic. These findings establish a basis for identifying functional natural variants, leading to a new understanding typical and atypical sociability.     

"Respect for the Rights of Others Is Peace": Learning Aggression versus Nonaggression among the Zapotec

This article examines differences in aggression between two Zapotec communities in Oaxaca, Mexico. An ethological study of three- to eight-year-old children (N = 48) reveals statistically significant intercommunity differences in children's serious and play aggression, corresponding to ethnographically observed intercommunity differences in adult behavior. The parallels between adult and children's conduct within the communities support the conclusion that different social learning environments contribute to the maintenance across generations of divergent ideologies, values, and patterns of social interaction related to violence or peacefulness. Social learning and socialization processes also can be viewed as interacting with economic, historical, and ideological influences. The findings suggest that studies of violence that neglect social learning influences may be providing only partial explanations.     

Comparison of two introduction methods for African elephants (Loxodonta africana)

Managers must consider an animal's potential for aggression when they decide to change or form a captive social group formation. In this study we compared two introduction methods (termed “sequential” and “nonsequential” introductions) in African elephants to assess their effectiveness in managing aggression and minimizing stress. Both introduction methods included four phases: baseline, visual contact, limited tactile contact, and physical introduction. In the sequential introduction, these steps were followed sequentially, and empirical data were considered during decision‐making. In the nonsequential introduction, these steps were not followed sequentially, and decision‐making was based primarily on intuitive assessments by animal managers. Behavioral data and fecal corticoid concentrations were measured throughout both types of introduction. The behavior categories measured included active aggression, passive aggression, submissive behavior, undesirable/stress‐related behavior, and affiliative behavior. While the role of affiliative behavior was surprising, general behavior patterns were characterized by increases in behavior as animals progressed to the next phase of introduction regardless of introduction type. These increases then attenuated over time during each phase. Overall, less behavior was observed during the sequential introduction, as predicted. The data suggest that the sequential introduction managed aggression more effectively. Similar patterns were predicted for undesirable/stress‐related behavior and fecal corticoid concentration. Undesirable/stress‐related behavior was a poor predictor of observed behavior patterns. Although the patterns differed from those predicted, higher concentrations of fecal corticoids were measured during the nonsequential introduction and correlated significantly only with submissive behavior. While more investigation is warranted, the data indicate that the nonsequential introduction brought about an increased physiological response. Overall, the sequential introduction method appeared to manage aggression and stress better than the nonsequential technique. Every introduction is subject to factors that can influence success, such as staff experience, the design of the facility, and the animals' social histories. It is hoped that the rigorous sequential protocol will be a useful tool in the animal manager's “toolbox” for planning and implementing introductions. Applications of this introduction method are also discussed. Zoo Biol 23:109–126, 2004. © 2004 Wiley‐Liss, Inc.     

Further evidence for the role of nitric oxide in maternal aggression: effects of L-NAME on maternal aggression towards female intruders in Wistar rats

It has been shown that nitric oxide (NO) increases aggression in male mice, whereas it decreases aggression in lactating female mice and prairie voles. It is also known that aggression can be exhibited at different levels in rodent species, strain or subtypes. The aims of this study were to investigate the proportion of aggressiveness in Wistar rats, the effect of intraperitoneally administered nonspecific nitric oxide synthase (NOS) inhibitor L-NAME (NG-nitro L-arginine methyl ester) on maternal aggression towards female intruders, and whether these effects are due to NO production or not. Rats were given saline intraperitoneally on the postpartum Day 2 and aggression levels were recorded. The same rats were given 60 mg/kg L-NAME or D-NAME (NG-nitro D-arginine methyl ester) on the postpartum Day 3 and their effects on aggression levels were compared to saline. While L-NAME administration did not cause any differences in the total number of aggressive behavior, aggression duration and aggression intensity, it reduced the proportion of animals showing aggressive behavior. In addition, the latency of the first aggression was significantly increased by L-NAME. In the D-NAME group, however, no significant change was found. Our results have shown that L-NAME reduces maternal aggression towards female intruders in Wistar rats through inhibition of NO production. These results suggest that the role of NO in offensive and defensive maternal aggression shares neural mechanisms.     

Etho-biochemical mechanisms of early differentiation in juveniles of the Atlantic salmon <Emphasis Type="Italic">Salmo salar</Emphasis>

The social status of hatchery-reared juveniles of Atlantic salmon Salmo salar at the age of 11–19 months in conditions of lack of shelters was investigated experimentally. It was demonstrated that biochemical differentiation in such juveniles begins at the age of 13 months—one month before the first differences in the social status of fish and four months prior to the beginning of smoltification. The dominants occupy bottom areas with shelters and extrude the subordinates to the water column. The subordinates undergo smoltification or die from aggression of the dominants. Concentrations of dopamine, noradrenalin, and of their metabolites in the brain of fish in the beginning of smoltification were higher in the dominants and, by the end of smoltification, were higher in smolts. The social behavior of fish is considered to be one of the ethological mechanisms of differentiation of salmon juveniles into smolts and parr.     

Offenders tend to be heavier: experimental encounters in mangrove-dwelling monitor lizards (<Emphasis Type="Italic">Varanus indicus</Emphasis>)

The evolution of male-biased sexual size dimorphism is often explained by sexual selection providing competitive advantage to the larger males. The aggressive interactions are often dangerous and energy consuming; thus, it is advantageous to reduce the risks by adjusting behavior to correspond with body size as a predictor of fighting success. Organization of contests into distinct phases with the initial displays preceding the real combat allows individuals to assess the body size and strength of the rival. We staged interactions between mangrove-dwelling monitor lizards (Varanus indicus) to uncover the initialization of aggression and factors determining the course of an encounter. The analyses revealed the importance of both absolute and relative body size of encountering males. The attack rate increases with the body weight of the lizard and offenders initializing a contact phase of the fight tend to be the heavier male of the dyad. Regardless of the final outcome of the combat, the results show that only short visual contact provides sufficient information about the body size of the opponent. This enables combatants to determine whether to initiate the fight or not. This finding together with the ethological details of contests provides the first evidence for the ability of mutual assessment in varanids.     

Increased depressive-like traits in an animal model of premenstrual irritability

Women are at higher risk of anxiety and mood disorders, especially at transitions across the reproductive life cycle (premenstruum, postpartum, menopause). Premenstrual dysphoric disorder (PMDD) is one of female mood disorders associated with changing ovarian hormone levels. Because anxiety and depression frequently occur in women with PMDD, premenstrual dysphoria might be a manifestation of certain vulnerability traits increasing the risk of those disorders. The present study was conducted to elucidate a potential association between estrous cycle-dependent aggression, the rodent model of "premenstrual irritability" (resident-intruder test), and anxiety (elevated plus maze), depressive-like traits (forced swim test) as well as carbohydrate craving in female Wistar rats. Some aggressive and nonaggressive females were restraint-stressed before testing to determine their sensitivity to stress at different hormonal stages. The results revealed that females expressing the estrous cycle-dependent aggression but not those not expressing cycle-dependent aggression spent longer time immobile and shorter time swimming in the forced swim test at metestrus compared to proestrus phase of the estrous cycle. There was no difference between aggressive and nonaggressive females in anxiety, locomotor activity and sensitivity to restraint stress and sucrose consumption. The present study suggests a common neurobiological background for the estrous cycle-dependent aggression and depressive-like traits in rodents. This phenomenon could potentially aid the elucidation of premenstrual emotional dysfunctions and might be used as an ethological model to study a biochemical and genetic proneness to depression.     

Ketogenic Diet Improves Core Symptoms of Autism in BTBR Mice

Autism spectrum disorders share three core symptoms: impaired sociability, repetitive behaviors and communication deficits. Incidence is rising, and current treatments are inadequate. Seizures are a common comorbidity, and since the 1920’s a high-fat, low-carbohydrate ketogenic diet has been used to treat epilepsy. Evidence suggests the ketogenic diet and analogous metabolic approaches may benefit diverse neurological disorders. Here we show that a ketogenic diet improves autistic behaviors in the BTBR mouse. Juvenile BTBR mice were fed standard or ketogenic diet for three weeks and tested for sociability, self-directed repetitive behavior, and communication. In separate experiments, spontaneous intrahippocampal EEGs and tests of seizure susceptibility (6 Hz corneal stimulation, flurothyl, {"type":"entrez-protein","attrs":{"text":"SKF83822","term_id":"1156217297"}}SKF83822, pentylenetetrazole) were compared between BTBR and control (C57Bl/6) mice. Ketogenic diet-fed BTBR mice showed increased sociability in a three-chamber test, decreased self-directed repetitive behavior, and improved social communication of a food preference. Although seizures are a common comorbidity with autism, BTBR mice fed a standard diet exhibit neither spontaneous seizures nor abnormal EEG, and have increased seizure susceptibility in just one of four tests. Thus, behavioral improvements are dissociable from any antiseizure effect. Our results suggest that a ketogenic diet improves multiple autistic behaviors in the BTBR mouse model. Therefore, ketogenic diets or analogous metabolic strategies may offer novel opportunities to improve core behavioral symptoms of autism spectrum disorders.     

Cortisol controls the pubertal development of agonistic behavior in male golden hamsters via type II corticosteroid receptors

In male golden hamsters, agonistic behavior undergoes a pubertal transition from play fighting to adult aggression. Previous studies have shown that this aspect of behavioral development is associated with pubertal increases in glucocorticoids and that daily social stress or injections of a synthetic glucocorticoid accelerate the transition. The goals of this study were to confirm the effects of cortisol on the development of agonistic behavior and to investigate the role of type II corticosteroid receptors in this process. First, animals treated with cortisol during early puberty [from postnatal days 31 (P-31) to P-36] showed an accelerated transition from play fighting to adult aggression. In a second experiment, the behavioral effects of cortisol were blocked by a co-treatment with a type II corticosteroid receptor antagonist. These findings are the first to show a facilitating role for type II corticosteroid receptors in the pubertal development of a social behavior. As such, these findings provide new insights into the neuroendocrine mechanisms controlling behavioral development during puberty.     

Effects of repeated experience of aggression on aggressive motivation and development of anxiety in male mice

The sensory contact technique allows an aggressive type of behavior to be formed as a result of repeated experience of social victories in daily agonistic confrontations. In mice of the low-aggressive and high-emotional CBA/Lac strain repeated positive fighting experience increases plus-maze anxiety. Behavioral reactivity of males to other conspecifics in the partition test (which measures aggressive motivation) significantly rises. It is concluded that repeated experience of aggression provokes the development of anxiety in male mice. The results suggest that level of anxiety and its behavioral realization depend on duration of aggressive experience and genetic strain.