Aggressive Bouts Research Articles

FKBP5 inhibitors modulate alcohol drinking and trauma-related behaviors in a model of comorbid post-traumatic stress and alcohol use disorder.

Post-traumatic stress disorder (PTSD) leads to enhanced alcohol drinking and development of alcohol use disorder (AUD). Identifying shared neural mechanisms might help discover new therapies for PTSD/AUD. Here, we employed a rat model of comorbid PTSD/AUD to evaluate compounds that inhibit FK506-binding protein 51 (FKBP5), a co-chaperone modulator of glucocorticoid receptors implicated in stress-related disorders. Male and female rats received a familiar avoidance-based shock stress followed by voluntary alcohol drinking. We then assessed trauma-related behaviors through sleep bout cycles, hyperarousal, fear overgeneralization, and irritability. To evaluate the role of stress and alcohol history on the sensitivity to FKBP5 inhibitors, in two separate studies, we administered two FKBP5 inhibitors, benztropine (Study 1) or SAFit2 (Study 2). FKBP5 inhibitors were administered on the last alcohol drinking session and prior to each trauma-related behavioral assessment. We also measured plasma corticosterone to assess the actions of FKBP5 inhibitors after familiar shock stress and alcohol drinking. Benztropine reduced alcohol preference in stressed males and females, while aggressive bouts were reduced in benztropine-treated stressed females. During hyperarousal, benztropine reduced several startle responseoutcomes across stressed males and females. Corticosterone was reduced in benztropine-treated stressed males. The selective FKBP5 inhibitor, SAFit2, reduced alcohol drinking in stressed males but not females, with no differences in irritability. Importantly, SAFit2 decreased fear overgeneralization in stressed males and females. SAFit2 also reduced corticosterone across stressed males and females. Neither FKBP5 inhibitor changed sleep bout structure. These findings indicate that FKBP5 inhibitors modulate stress-related alcohol drinking and partially modulate trauma-related behaviors. This work supports the hypothesis that targeting FKBP5 may alleviate PTSD/AUD comorbidity.

Bite Force and Feeding Traces of Tyrannosaurusthroughout Ontogeny: A Review

Bite marks attributed to adult Tyrannosaurus rexare common in the fossil record and have been subject to numerous studies, though relatively few bite marks attributed to T. rexhave been traced to juveniles. However, a series of recent studies have contributed new information on bite force, behavior, and ecological interactions of juvenile Tyrannosaurus rex, providing insight into ontogenetic changes in lifestyle and ecological roles of juvenile tyrannosaurs in the late Cretaceous of North America. Recent bite force estimates for a juvenile Tyrannosaurus rexwere based on mechanical tests designed to replicate bite marks previously attributed to a T. rex of approximately 13 years old in the centrum of a caudal vertebra of Edmontosaurus(BMR P2007.4.1) and the left maxilla and nasal of a juvenile Tyrannosaurus (BMR P2002.4.1). Results indicate an estimated bite force of 5,641.19 N, and suggest that bite forces were increasing parallel to growth and were utilizing the same prey as adults. Additionally, evidence of intraspecific aggression in the form of lesions resulting from face biting are present in over 50% of juvenile and adult tyrannosaurs. The high frequency of facial scars positively correlates with the inferred onset of sexual maturity. Furthermore, lesions attributed to a Trichomonas gallinae‐like parasite are present on the dentaries and surangulars of adult tyrannosaurs. Presented here is the first evidence of similar pathologies on a juvenile Tyrannosaurus rex that also possesses facial scars from intraspecific aggression, supporting a cause‐and‐effect relationship between the two groups of facial pathologies. Collectively, these findings suggest tyrannosaurs increased interactions, aggressive bouts, and potential transmission of parasites at the onset of sexual maturity as they were moving into different ecological niches. Furthermore, the frequency and category of pathologies in late Cretaceous tyrannosaurs and late Jurassic theropods of North America are compared with the unique guild structures of tyrannosaurs in the late Cretaceous of North America, suggesting a possible relationship between theropod diversity, behavior, and parasitism.

Localizing a metabolic focus during a functional seizure with fluorodeoxyglucose positron emission tomography-computed tomography

Traumatic brain injuries can lead to long-term mental seizures that are difficult to differentiate from dissociative psychogenic symptoms, respectively, psychogenic nonepileptic seizures. Recent articles have drawn attention to the need of differentiation of psychological and brain trauma-related symptoms in survivors of violence. This case study reflects a diagnostic step in a 20-year-male who reported to have been subjected to torture, including blunt force to the head 2 years before examination. He suffers from episodical headaches followed by mental bouts of aggression and restlessness. We performed a brain 18F-fluorodeoxyglucose positron emission tomography (PET)-computed tomography to identify a cerebral correlate of the psychogenic seizures. The examination yielded a hypermetabolic focus in the frontal superior parasagittal region. Psychogenic seizures can frequently be observed as culture-specific “idioms of distress” and can challenge diagnostic evaluation, especially in the victims of violence with an additional history of blunt brain trauma. The advances in molecular imaging such as PET can be expected to play a crucial role in forensic and clinical assessment in the increasing number of such patients.

A case of frontal lobe syndrome.

Frontal lobe syndrome is a broad term used to describe the damage of higher functioning processes of the brain such as motivation, planning, social behavior, and language/speech production.[1] It can occur due to disease, head trauma, or tumor. It is characterized by a change in personality and behavior in a previously normal individual. A 17-year-old boy, educated up to 9th std, living with parents and younger sibling, was brought to the psychiatry outpatient department with complaints of irritability, aggressive behavior, easy distractibility, restlessness, impulsive behavior, inappropriate social behavior, and wandering tendency since 1.5 years. The patient was apparently alright 1.5 years back when he met with a road traffic accident (RTA), sustained closed head injury, and had right ear bleed, following which he had loss of consciousness for 18 days requiring ventilatory support. On regaining consciousness, the patient had memory loss for events a few days prior and multiple days after the RTA, irritability, anger outbursts, impulsivity, abusive behavior, overfamiliarity, jocularity, wandering behavior, disinhibition, and distractibility. He had unprovoked bouts of aggression and would start abusing those around him. He could not sit still for any task and would leave conversations midway, focusing his attention on some other activity. When he got unmanageable at home, he was shown to a psychiatrist a month after the accident and he was prescribed: tablet risperidone 3 mg + tablet trihexyphenidyl 2 mg, tablet olanzapine 5mg BD, and valproate 250 mg BD. The treatment was partially effective in treating his mood and behavioral changes, but symptoms still persisted. There is no significant past medical history, no family history of any psychiatric illness, and no history of substance use. His general physical and systemic examinations were within normal limits. On central nervous system examination, anosmia was present, grip was reduced in the left hand, dysdiadokokinesia showed frequent sequencing errors, and gait was suggestive of frontal ataxia. On the Frontal lobe assessment patient score was: 5/18 (normal score of 15); motor functions: grip strength was reduced on the left side; fine motor speed was reduced in the left hand with errors; premotor functions: sensorimotor integration was slower in the left hand; dorsolateral/ executive functions: complex and directed attention was normal; multiple response alternatives: open set F, A, S beginning words – very poor, behavioral inflexibility: Luria's bilateral hand movements – negative; Wisconsin card sorting test was abnormal; orbital/inhibitory functions: behavioral disinhibition – go no go test was abnormal, Stroop test was abnormal; anosmia was present; abnormal behavior during testing: poor/no insight into deficits, inappropriate social behavior, perseveration present, easily agitated, and hyperactive. From the above tests, we concluded that the patient had loss of executive functions along with disinhibition which is seen in frontal lobe syndrome (dysexecutive syndrome). Mental status examination revealed overfamiliarity, jocularity, and disinhibited behavior. Speech was spontaneous with increased rate, monotonous, nasal voice, unclear words and increased reaction time. His mood was irritable and labile. Delusions/ obsessions/ suicidal ideas were absent. X ray skull showed multiple frontal bone fractures. CT scan of brain showed bilateral frontal bone fractures, orbital and maxillary injuries along with extensive edema. With the diagnosis of frontal lobe syndrome, he was treated with tablet olanzapine 5 mg BD and tablet valproate 500 mg BD. Our case report demonstrates the drastic change in behavior and personality in a patient with traumatic brain injury causing damage to the frontal lobe. He was an above-average student prior to the RTA but could not function normally since then and was unmanageable at home with frequent bouts of unprovoked aggression. He also required supervision to carry out daily activities. Frontal lobe is responsible for higher mental functions including executive functions, voluntary movement, and language and is prone to injury due to its placement. It is also considered the behavior and emotion control center and home to our personality, injury to which can lead to serious consequences. Frontal lobe damage can have devastating consequences on the patient as well as the relatives. Psychotropic medications can be used to an extent to control the behavioral disturbance and rehabilitation could be useful for support, although prognosis is poor for such patients. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Diet-regulated behavior: FVB/N mice fed a lean diet exhibit increased nocturnal bouts of aggression between littermates.

The hyperactive FVB/N inbred mouse strain is widely used for transgenic research applications, although rarely for behavioral studies. These mice have visual impairments via retinal degeneration, but are considered highly intelligent and rely largely on olfaction. While investigating diet-induced obesity in autotaxin transgenic FVB/N mice, we observed an increase in the necessity for male, but not female, cage separations. Based on the observations, we hypothesized that feeding FVB/N mice a lean diet increases nocturnal bouts of aggression between male littermates. The diets of adult littermates were switched from normal chow to either ad libitum high-fat (45% fat) or lean (10% fat) matched diets for 27 weeks, whereby the mice reached an average of 43 g versus 35 g, respectively. Then, cage separations due to nocturnal bouts of aggression became mandatory, even though littermates peacefully cohabitated for 10-16 weeks previously. Since the data was of an unusual nature, it required uncommon statistical methods to be engendered to evaluate whether and where significance existed. Therefore, utilizing the randomization and population models, we established a methodology and postulated that either testosterone, the autotaxin transgene or diet alteration was the causal factor. Statistical evaluation demonstrated a significant correlation between cage separations and aggressive behavior associated with the lean-diet-fed mice, not autotaxin. Biochemical data did not appear to explain the behavior. In contrast, energy metabolism highlighted differences between the groups of normally hyperactive mice by diet. This characteristic makes FVB/N male mice unsuitable subjects for long-term studies with lean-diet modifications.

Group lactation from 7 or 14 days of age reduces piglet aggression at weaning compared to farrowing crate housing

Early life experiences can affect social behaviour in later life, but opportunities for socio-behavioural development are often overlooked in current husbandry practices. This experiment investigated the effects of rearing piglets in two-stage group lactation (GL) system from 7 or 14 days of age on piglet aggression at weaning. Three lactation housing treatments were applied to a total of 198 piglets from 30 litters of multiparous sows. All dams farrowed in standard farrowing crates (FCs). Group lactation litters were transferred with their dam at 7 (GL7) or 14 days (GL14) postpartum to GL pens (one pen of five sows at 8.4 m2/sow and one pen of seven sows at 8.1 m2/sow, per GL treatment). Farrowing crate litters remained with their dam in a single litter until weaning. At weaning, 10 to 14 piglets from two unfamiliar litters from the same housing treatment were mixed into pens (n=5 pens/treatment) and their behaviour was continuously recorded for 3.5 h. For each pen, the frequency of aggressive bouts (reciprocal and non-reciprocal aggression lasting <5 s), the frequency and duration of fights (reciprocal aggression lasting ⩾5 s) and bullying events (non-reciprocal aggression lasting ⩾5 s) were recorded, along with whether interactions involved familiar or unfamiliar piglets. Aggressive bouts delivered by FC piglets were approximately 1.5 and 3.0 times more frequent than that delivered by GL7 and GL14 piglets, respectively (40.5, 16.7 and 9.9 bouts/pig, respectively; P<0.05). Fighting was more frequent (1.6, 0.3 and 0.4 fights/pig, respectively; P<0.001) and fights were longer (83, 15 and 32 s fight/pig, respectively; P<0.001) between FC piglets than between GL7 or GL14 piglets. Bullying did not differ between housing treatments (P>0.05). GL7 and GL14 piglets engaged in a similar number of fights with unfamiliar as familiar piglets, but FC piglets had almost three times as many fights with unfamiliar than with familiar piglets (P<0.05). This experiment confirms the benefits of GL housing for pig social development. Further investigation is required to determine whether mixing before 14 days postpartum has implications for other indicators of animal welfare and productivity in a two-stage GL housing system.

Reprint of “Rearing piglets in multi-litter group lactation systems: Effects on piglet aggression and injuries post-weaning”

This experiment investigated the effects of rearing piglets in a multi-litter lactation system on piglet aggression at weaning. The following four pre-weaning treatments were applied to 72 sows and their litters (n=642 piglets); (1) Farrowing crate (‘FC’ − n=24 sows), (2) PigSAFE pens, in which sows and piglets are loose housed, (‘PS’ − n=24 sows), (3) Farrowing crate and group lactation (‘GLFC’ − n=12 sows), and (4) PigSAFE and group lactation (‘GLPS’ − n=12 sows). FC and PS piglets remained in treatment from birth (day 0) until weaning (day 27). GLFC and GLPS piglets were housed in FC and PS, respectively, from day 0 to 14 after which they were transferred (with their dams) to group lactation pens (n=6 sows and litters/pen), where they remained until weaning. Piglet weights were recorded at day 13 and 26. At weaning piglets were mixed into pens of four litters from FC, PS, or GL (2 GLFC litters and 2 GLPS litters) treatments and behaviour was continuously recorded for 2h. Aggression (reciprocal and non-reciprocal aggression of duration <5s) and fights (reciprocal aggression of duration ≥5s; frequency; total and average duration, latency to fight) were recorded for each litter. Six piglets from each litter were randomly selected for skin lesion scoring on day 26 and 24h post-weaning. GLFC and GLPS piglets had a lower growth rate than FC and PS piglets from day 13 to 26 (P<0.01) but there was no difference in weight at day 13 (P=0.11) or day 26 (P=0.17), or in skin lesions at day 26 (P=0.26). GL piglets delivered fewer bouts of aggression (P<0.01), fought less frequently in the 2h post-mixing at weaning (P<0.01) and had sustained fewer skin lesions 24h later (P<0.01) than FC or PS piglets. GL piglets also had shorter fights (P<0.01) and spent less total time fighting (P=0.04) than FC, but not than PS, piglets. These results highlight the possible importance of the early social environment on the development and regulation of aggressive behaviour in the pig. Due to the implications of aggression and injury on both animal welfare and productivity, there is a need for further investigation into the effects of housing piglets in multi-litter lactation systems.

Contemplating stem cell therapy for epilepsy-induced neuropsychiatric symptoms.

Epilepsy is a debilitating disease that impacts millions of people worldwide. While unprovoked seizures characterize its cardinal symptom, an important aspect of epilepsy that remains to be addressed is the neuropsychiatric component. It has been documented for millennia in paintings and literature that those with epilepsy can suffer from bouts of aggression, depression, and other psychiatric ailments. Current treatments for epilepsy include the use of antiepileptic drugs and surgical resection. Antiepileptic drugs reduce the overall firing of the brain to mitigate the rate of seizure occurrence. Surgery aims to remove a portion of the brain that is suspected to be the source of aberrant firing that leads to seizures. Both options treat the seizure-generating neurological aspect of epilepsy, but fail to directly address the neuropsychiatric components. A promising new treatment for epilepsy is the use of stem cells to treat both the biological and psychiatric components. Stem cell therapy has been shown efficacious in treating experimental models of neurological disorders, including Parkinson’s disease, and neuropsychiatric diseases, such as depression. Additional research is necessary to see if stem cells can treat both neurological and neuropsychiatric aspects of epilepsy. Currently, there is no animal model that recapitulates all the clinical hallmarks of epilepsy. This could be due to difficulty in characterizing the neuropsychiatric component of the disease. In advancing stem cell therapy for treating epilepsy, experimental testing of the safety and efficacy of allogeneic and autologous transplantation will require the optimization of cell dosage, delivery, and timing of transplantation in a clinically relevant model of epilepsy with both neurological and neuropsychiatric symptoms of the disease as the primary outcome measures.

Differential activation of vasotocin neurons in contexts that elicit aggression and courtship

Despite continued study on the neurobiological bases of aggressive and sexual behaviors, it is still not well understood how the brain integrates social information with physiological and neural states to produce context-specific behavioral outcomes. In fishes, manipulation of endogenous levels of arginine vasotocin (AVT) through peripheral and intracerebroventricular pharmacological injections results in significant changes in social behaviors, including aggressive and reproduction-related behaviors. In addition, many features of AVT neurons have been shown to correlate with social status and associated behavioral phenotypes. In this study, we used the immediate early gene egr-1 as a marker for neuronal activity and quantified the number of AVT neurons that were positive for egr-1 mRNA by in situ hybridization in Astatotilapia burtoni males that were exposed to either a social context that would elicit aggression or to one that would elicit courtship. In these social settings, focal males readily displayed context- appropriate bouts of aggression (towards the opponent) or bouts of courting (towards females). We found that males that fought had higher levels of egr-1 expression in the preoptic area compared to courting males. A greater proportion of AVT cells was positive for egr-1 after a fight than after a bout of courting. We mapped mRNA distribution of AVT V1a receptor subtypes v1a1 and v1a2 in the brain and identified overlapping areas of expression in nuclei in the ventral telencephalon, hypothalamus and thalamus as key areas for AVT signaling in males.

Rearing piglets in multi-litter group lactation systems: Effects on piglet aggression and injuries post-weaning

This experiment investigated the effects of rearing piglets in a multi-litter lactation system on piglet aggression at weaning. The following four pre-weaning treatments were applied to 72 sows and their litters (n=642 piglets); (1) Farrowing crate (‘FC’ − n=24 sows), (2) PigSAFE pens, in which sows and piglets are loose housed, (‘PS’ − n=24 sows), (3) Farrowing crate and group lactation (‘GLFC’ − n=12 sows), and (4) PigSAFE and group lactation (‘GLPS’ − n=12 sows). FC and PS piglets remained in treatment from birth (day 0) until weaning (day 27). GLFC and GLPS piglets were housed in FC and PS, respectively, from day 0 to 14 after which they were transferred (with their dams) to group lactation pens (n=6 sows and litters/pen), where they remained until weaning. Piglet weights were recorded at day 13 and 26. At weaning piglets were mixed into pens of four litters from FC, PS, or GL (2 GLFC litters and 2 GLPS litters) treatments and behaviour was continuously recorded for 2h. Aggression (reciprocal and non-reciprocal aggression of duration <5s) and fights (reciprocal aggression of duration ≥5s; frequency; total and average duration, latency to fight) were recorded for each litter. Six piglets from each litter were randomly selected for skin lesion scoring on day 26 and 24h post-weaning. GLFC and GLPS piglets had a lower growth rate than FC and PS piglets from day 13 to 26 (P<0.01) but there was no difference in weight at day 13 (P=0.11) or day 26 (P=0.17), or in skin lesions at day 26 (P=0.26). GL piglets delivered fewer bouts of aggression (P<0.01), fought less frequently in the 2h post-mixing at weaning (P<0.01) and had sustained fewer skin lesions 24h later (P<0.01) than FC or PS piglets. GL piglets also had shorter fights (P<0.01) and spent less total time fighting (P=0.04) than FC, but not than PS, piglets. These results highlight the possible importance of the early social environment on the development and regulation of aggressive behaviour in the pig. Due to the implications of aggression and injury on both animal welfare and productivity, there is a need for further investigation into the effects of housing piglets in multi-litter lactation systems.

The role of anxiety in the development, maintenance, and treatment of childhood aggression.

The majority of aggressive children exhibit symptoms of anxiety, yet none of our developmental models of aggression incorporate the role of anxiety, and our treatments ignore this comorbidity. This article outlines a novel theoretical model that specifies three hypotheses about comorbid anxious and aggressive children: (a) unpredictable parenting induces anxiety in children that in turn triggers aggressive behavior; (b) prolonged periods of anxiety deplete children's capacity to inhibit impulses and trigger bouts of aggression, and aggression in turn functions to regulate levels of anxiety; and (c) minor daily stressors give rise to anxiety while cognitive perseveration maintains anxious moods, increasingly disposing children to aggress. Little or no research has directly tested these hypotheses. Extant research and theory consistent with these claims are herein reviewed, and future research designs that can test them specifically are suggested. The clinical implications most relevant to the hypotheses are discussed, and to improve the efficacy of treatments for childhood aggression, it is proposed that anxiety may need to be the primary target of treatment.

Hypothalamic vasopressin systems are more sensitive to the long term effects of social defeat in males versus females.

Vasopressin signaling has important effects on the regulation of social behaviors and stress responses, and is considered a promising pathway to target for new therapeutics of stress-induced psychiatric disorders. Although there is evidence for sex differences in the behavioral effects of arginine vasopressin (AVP), few data have directly compared the effects of stress on endogenous AVP signaling in males and females. We used California mice (Peromyscus californicus) to study the short and long term effects of social defeat stress on AVP immunoreactive cells in the paraventricular nucleus (PVN) and the posteromedial bed nucleus of the stria terminalis (BNSTmp). Acute exposure to defeat increased AVP/c-fos cells in the PVN and SON of both males and females. In contrast, there were sex differences in the long term effects of defeat. Males but not females exposed to defeat had less avp mRNA in the PVN, and in two experiments defeat reduced the number of AVP positive cells in the caudal PVN of males but not females. Interestingly, during relatively benign social encounters with a target mouse, there was a rapid decrease in AVP percent staining (including cell bodies and fibers) in the PVN of males but not females. Defeat reduced AVP percent staining in males, but did not block the socially induced decrease in percent staining. When mice were tested in resident-intruder tests, males exposed to defeat were no less aggressive than control males whereas aggression was abolished in females. However, bouts of aggression were positively correlated with the number of AVP neurons in the BNSTmp of control males but not stressed males, suggesting that different mechanisms mediate aggression in control and stressed males. These data show that while acute AVP responses to defeat are similar in males and females, the long term effects of defeat on AVP are stronger in males.

Influences of Relatedness, Food Deprivation, and Sex on Adult Behaviors in the Group‐living InsectForficula auricularia

AbstractThe evolution of group living is generally associated with the emergence of social behaviors that ensure fitness benefits to group members. However, the expression of these behaviors may depend on group composition, which can vary over time with respect to sex, starvation status, and relatedness. Here, we investigated (1) whether adults of the group‐livingEuropean earwig,Forficula auricularia, show cooperative behaviors toward conspecifics and (2) whether sex, food availability, and relatedness shape the nature and frequency of these behaviors. We conducted a full‐factorial experiment using 108 unisexual pairs of adults, in which we manipulated these three factors and video‐recorded the earwig behaviors for 45 min. Our results revealed that adults mostly expressed self‐directed and aggressive behaviors. Nevertheless, they also showed allogrooming, a social behavior that offers scope for cooperation. Pairs of males displayed longer bouts of aggression and allogrooming (when it occurred) than pairs of females. Food deprivation had no effect on male behaviors, but females spent less time self‐grooming and walking when they were food deprived. Finally, low relatedness between adults did not influence any of the measured behaviors, but exacerbated frass production, possibly due to social stress. Overall, these results indicate the limited role of cooperation amongF. auriculariaadults during their group‐living phase.

Steroid hormone levels in calling males and males practicing alternative non-calling mating tactics in the green treefrog, Hyla cinerea

Circulating glucocorticoids and androgens often figure prominently in mating tactic expression in vertebrates. In anuran amphibians (frogs and toads), for example, recent models predict that the depletion of energy reserves during vocalization will result in increased glucocorticoid levels; high glucocorticoids are expected to negatively affect androgen level to mediate transitions from calling to non-calling behavior. Consistent with these predictions, we show that male green treefrogs (Hyla cinerea) adopting an alternative non-calling “satellite” mating tactic were in poorer condition and had higher circulating corticosterone levels and lower androgen levels than calling males. Body condition was inversely related to corticosterone level and positively related to testosterone, but not dihydrotestosterone, level. Corticosterone level was inversely related to testosterone level but not dihydrotestosterone level. Lastly, we show that calling males that were involved in aggressive bouts had higher corticosterone levels than calling males that were not involved in aggressive bouts. Our results are thus consistent with the prediction that aggressive interactions with conspecific males contribute to high corticosterone levels in satellite males that were observed to lose aggressive contests with larger calling males.

Effects of Chronic Central Arginine Vasopressin (AVP) on Maternal Behavior in Chronically Stressed Rat Dams.

Exposure of mothers to chronic stressors during pregnancy or the postpartum period often leads to the development of depression, anxiety, or other related mood disorders. The adverse effects of mood disorders are often mediated through maternal behavior and recent work has identified arginine vasopressin (AVP) as a key neuropeptide hormone in the expression of maternal behavior in both rats and humans. Using an established rodent model that elicits behavioral and physiological responses similar to human mood disorders, this study tested the effectiveness of chronic AVP infusion as a novel treatment for the adverse effects of exposure to chronic social stress during lactation in rats. During early (day 3) and mid (day 10) lactation, AVP treatment significantly decreased the latency to initiate nursing and time spent retrieving pups, and increased pup grooming and total maternal care (sum of pup grooming and nursing). AVP treatment was also effective in decreasing maternal aggression and the average duration of aggressive bouts on day 3 of lactation. Central AVP may be an effective target for the development of treatments for enhancing maternal behavior in individuals exposed to chronic social stress.

An empirical examination of sex differences in scoring preschool children’s aggression

Sex differences in adults’ observations and ratings of children’s aggression was studied in a sample of preschool children ( N = 89, mean age = 44.00 months, SD = 8.48). When examining the direct observations made by trained observers, male observers, relative to female observers, more frequently recorded aggressive bouts, especially of boys. On rating scales assessing aggression, trained male raters also gave higher aggressive ratings than female raters. Lastly, we compared the ratings of trained female raters and female teachers on the same scale and found no differences. Results are discussed in terms male raters’ and observers’ prior experiences in activating their experiential schemata where males’ greater experience in aggression, relative to that of females, leads them to perceive greater levels of aggression.

Intraspecific Competition Between Adult Females of the Hyperparasitoid Trichomalopsis Apanteloctena (Hymenoptera: Chelonidae), for Domination of Cotesia kariyai (Hymenoptera: Braconidae) Cocoons

Abstract The development of parasitoid wasps is dependent on the finite resources contained in a single item of resource (=host) that is frequently not much larger than the adult parasitoid. When the costs of egg production are high, and host distribution is highly aggregated, parasitoid females may spend prolonged periods guarding their eggs and host resources as an adaptive strategy to optimize their inclusive fitness. Here, we examine aggressive interactions between the females of the secondary hyperparasitoid Trichomalopsis apanteloctena (Crawford) (Hymenoptera: Chelonidae), for control of cocoon clusters of their primary parasitoid host Cotesia kariyai (Watanabe) (Hymenoptera: Braeonidae). Generally, larger female hyperparasitoids were more successful at defending cocoon clusters than smaller female hyperparasitoids. However, when first encountering host cocoons, larger females behaved more aggressively toward conspecific wasps than smaller females. After occupation of a host cocoon cluster, females of similar size rarely engaged in physical combat, but both females primarily exhibited threatening behavior toward each other. However, larger females usually displaced smaller females which had initially occupied cocoon clusters. Some small females chewed through the outer cocoon silk layer to avoid being displaced by larger females and these wasps were able to continue parasitizing cocoons of C. kariyai. Extended bouts of aggression tended to reduce the number of eggs laid by the guarding female because of disruption of oviposition behavior. The relationship between the size of host cocoons and body mass in T. apanteloctena was also examined. The size of hyperparasitoid progeny was strongly correlated with host size. However, the relationship between maternal size, the number of matured eggs in her ovarioles and body mass in her offspring was not significant.

Age, musth and paternity success in wild male African elephants, Loxodonta africana

Male African elephants experience intense intrasexual selection in gaining access to oestrous females, who represent a very scarce and highly mobile resource. An unusual combination of behavioural and physiological traits in males probably reflects this intense selection pressure. Males show prolonged growth, growing throughout much or perhaps all of their long life span (ca. 60e65 years), and they show musth, a physiological and behavioural condition exclusive to elephants, which is manifested by bouts of elevated testosterone and aggression and heightened sexual activity. Most observed matings are by males over 35 years of age and in musth, suggesting that age and musth are both important factors contributing to male reproductive success. Here we report the results of a genetic paternity analysis of a well-studied population of wild African elephants. Patterns of paternity for 119 calves born over a 22-year period showed significant effects of both age and musth on paternity success. Among males in musth, paternity success increased significantly with age until the very oldest age classes, when it modestly declined. When not in musth, males experienced relatively constant, low levels of paternity success at all ages. Thus, despite the importance of both musth and age in determining male paternity success, adult males both in and out of musth, and of all ages, produced calves. In general, however, older males had markedly elevated paternity success compared with younger males, suggesting the possibility of sexual selection for longevity in this species.

Social dominance in preschool classrooms.

The authors examined preschoolers' aggressive and cooperative behaviors and their associations with social dominance. First and as predicted, directly observed aggressive interactions decreased across the school year, and same-sex aggression occurred more frequently than cross-sex aggression. Next, the authors examined the relation between aggression and reconciliation, cooperation, and social display variables. Teacher ratings of children's aggression related to observed aggression but not to observed "wins" of aggressive bouts. Instead, wins were related to cooperation and display variables. Finally, they examined the relative power of wins and cooperation in predicting 2 measures of social dominance. After age was controlled, wins alone predicted teacher-rated social dominance. Results are discussed in terms of different forms of competition and how school ethos affects these forms.

Bioacoustic Monitoring of Aggression in Group-Housed Rhesus Macaques

Many captive primate facilities house rhesus macaques in multimale–multifemale social groups in large enclosures that simulate the natural social and environmental features characteristic of the species, enhancing their reproductive performance as well as their psychological well-being, yet one of the most difficult management problems in socially housed macaques is their propensity for exhibiting spontaneous bouts of deleterious aggression. To address this management problem, an automated bioacoustic monitoring system might be developed that is capable of detecting and forecasting problematic patterns of contact aggression. To evaluate the utility of this approach, this study examined the magnitude of aggression and the co-occurrence of certain vocalization types and aggression in 10 groups of rhesus macaques. The data confirmed aggression as a significant problem in rhesus groups and indicated that certain patterns of vocalizations are indicative of the type or level of aggression. The detection and classification of these vocalization types need further research to eventually design and implement an efficacious bioacoustic system for monitoring aggression in rhesus macaques.