Intra-female aggression in the mouse (Mus musculus domesticus) is linked to the estrous cycle regularity but not to ovulation

Intraspecific communication between mice takes place mainly via urinary chemosignals or "pheromones". Pheromones can influence aggressive and reproductive behavior as well as the neuroendocrine condition of the recipient female mice via their olfactory system. In this study, reproductively cyclic mice in the estrus phase were used to test intraspecific agonistic aggressive behavior. Data were obtained also on the count of the eggs shed in the oviducts. The results showed that (i) individually housed female mice are more aggressive toward an intruder female mouse than grouped mice, (ii) mice in which the vomeronasal organ was removed show aggressive behavior intermediate between individually housed and grouped mice, and (iii) a within group analysis did not show a positive correlation between aggression and presence of shed eggs in the oviducts.     

Psychological strain and emotional labor among police-officers: A diary study

The authors examined the relationship between psychological strain, emotional dissonance and emotional job demands during a working day of 65 Dutch (military) police officers, using a 5-day diary design. We hypothesized that emotional dissonance partly mediated the relationship between psychological strain at the start and at the end of a work shift. We also tested the mediating role of emotional dissonance between emotional job demands and psychological strain at the end of a work shift. Results of structural equation modeling analyses showed that psychological strain at the start of a work shift had a positive effect on the experience of emotional dissonance and psychological strain at the end of a work shift. Emotional dissonance partly mediated the relationship between psychological strain at the start and psychological strain at the end of a work shift. Results are discussed in light of conservation of resources theory (Hobfoll, S. E. (1988). The ecology of stress. New York: Hemisphere Publishing Corporation).     

Perceived Social Support and Caregiver Strain in Caregivers of Children with Tourette’s Disorder

The research on Tourette’s disorder (TD), a neuropsychological disorder consisting of motor and phonic tics, has largely focused on individuals with TD and not on the caregivers of children with TD. We investigated the effects of several variables on caregiver strain of caregivers of children with TD, including perceived social support, caregiver characteristics, and characteristics of the child’s disorder. An online survey was completed by 140 caregivers of children with TD between the ages of 6 to 18 years. We performed a path analysis to examine the outcome of caregiver strain in relation to the research variables. Our results indicated that caregiver age, symptom severity of the child’s TD, and perceived social support accounted for variance in caregiver strain, and that perceived social support was a partial mediator of child’s symptom severity and caregiver strain. Symptom severity and caregiver strain were also related to the presence of other comorbid disorders, such as Oppositional Defiant Disorder (ODD), anxiety, or Attention Deficit Hyperactivity Disorder (ADHD) when compared to children either having no other comorbid disorders or other types of disorders.     

EFFECTS OF POINT‐LOSS PUNISHERS ON HUMAN SIGNAL‐DETECTION PERFORMANCE

Three experiments using human participants varied the distribution of point‐gain reinforcers or point‐loss punishers in two‐alternative signal‐detection procedures. Experiment 1 varied the distribution of point‐gain reinforcers for correct responses (Group A) and point‐loss punishers for errors (Group B) across conditions. Response bias varied systematically as a function of the relative reinforcer or punisher frequencies. Experiment 2 arranged two conditions — one where an unequal ratio of reinforcement (5:1 or 1:5) was presented without punishment (R‐only), and another where the same reinforcer ratio was presented with an equal distribution of point‐loss punishers (R+P). Response bias was significantly greater in the R‐only condition than the R+P condition, supporting a subtractive model of punishment. Experiment 3 varied the distribution of point‐gain reinforcers for correct responses across four unequal reinforcer ratios (5:1, 2:1, 1:2, 1:5) both without (R‐only) and with (R+P) an equal distribution of point‐loss punishers for errors. Response bias varied systematically with changes in relative reinforcer frequency for both R‐only and R+P conditions, with 5 out of 8 participants showing increases in sensitivity estimates from R‐only to R+P conditions. Overall, the results indicated that punishers have similar but opposite effects to reinforcers in detection procedures and that combined reinforcer and punisher effects might be better modeled by a subtractive punishment model than an additive punishment model, consistent with research using concurrent‐schedule choice procedures.     

Violent phenotype in SAL mice is inflexible and fixed in adulthood

Violence was shown to be qualitatively different from functional hyper‐aggression in mice selected for high aggression namely Short Attack Latency (SAL), Turku Aggressive (TA) and North Carolina (NC900) strains. This study aimed at investigating whether this adulthood violent phenotype as seen previously in the SAL mice is fixed and hence behaviorally inflexible right from day 1 of the experiment or consequential, i.e., subject to gradual change from functional aggression to violence. The functionally hyper‐aggressive strains namely TA and NC900 strains served as controls for the study. Methodologically, behavioral (in)flexibility was studied using the overall sequential structure of agonistic behavior. In particular, intra‐individual variations in the overall agonistic behavior as well as offensive, pre‐ and post‐offensive behavior transitions, directly related to the resident–intruder interactions were investigated. The SAL mice showed the least intra‐individual variation in their overall sequential agonistic structure as well as a fixed offense‐oriented agonistic behavior of highest magnitude when compared with the other strains. Additionally, the pre‐ and post‐ offensive transitions were most salient in the functionally hyper‐aggressive TA and NC900 strains, whereas virtually absent in the SAL mice. Thus, the violent behavior of the adult SAL mice is behaviorally inflexible or fixed, whereas the functionally hyper‐aggressive behavior of the adult TA and NC900 mice is behaviorally flexible and constantly adaptive to the opponent behavior, over 3 days of repeated resident–intruder interaction. Aggr. Behav. 35:430–436, 2009. © 2009 Wiley‐Liss, Inc.     

Psychological Distress in Caregivers of Liver and Lung Transplant Candidates

Although organ transplantation represents a stressful experience for the entire family, surprisingly little research has focused on the adjustment of caregivers. The purpose of this study was to examine what caregivers report to be the greatest benefits and stressors pretransplant, the prevalence of psychological distress and caregiver strain in pretransplant caregivers as compared to normative populations, and the physical, psychological, and demographic variables that predict distress. Fifty-two caregivers of transplant candidates (28 liver and 24 lung) completed a series of questionnaires, including the Psychosocial Adjustment to Illness Scale (PAIS-SR), SF-36 Health Survey, Caregiver Strain Index (CSI), and qualitative questions about benefits and stressors. The most commonly reported benefit of being a caregiver could be categorized as Helping the Patient, and the most common stressors were associated with Uncertainty/Waiting/Fears. Compared to normative samples of caregivers of patients with Alzheimer's disease, caregivers of liver transplant candidates reported more caregiver strain; there were no differences for lung transplant caregivers. Caregiver social functioning was found to be the only significant predictor of caregiver distress, with those caregivers who report greater distress also reporting extreme and frequent interference with normal social activities. Implications of these findings for psychological interventions are discussed.     

Intruders of differing reproductive status alter aggression differentially in early and late pregnant mice

Independent groups of early and late pregnant mice, housed individually, were observed with an intruder in their home cage. The intruders were either males, virgin, early, or late pregnant females. Male intruders were sniffed less, but more frequently and more severely attacked, than any type of female intruder, both by early and by late pregnant residents. While early pregnant females behaved similarly with the three types of female intruders, late pregnant animals treated them differently: they showed practically no aggression to late pregnant intruders, more to early pregnant ones and were most aggressive towards virgin female intruders. The possible relation of these findings to reproductive behaviour is discussed.     

Effects of D- and L-amphetamine on the predatory behavior of Southern grasshopper mice,onychomys torridus

Adult male and female southern grasshopper mice (Onychomys torridus) were tested for predatory aggression toward cricket prey 1 hr after single injections of d-amphetamine (1 or 10 mg/kg) or 1-amphetamine (1 or 10 mg/kg). At the lower dose, d-amphetamine decreased feeding behaviors, while I-amphetamine altered attack-related behaviors. At the higher dose, both stereoisomers appeared to be equipotent in significantly decreasing 5 measures of predatory aggression. These results suggest that brain dopamine and norepinephrine play important roles in the regulation of predatory aggression of Onychomys torridus.     

Social-relational exposures and well-being: Using multivariate twin data to rule-out heritable and shared environmental confounds

The aims of the present study were as follows: (1) Using a large sample of adults, estimate overlap between social-relational exposures measured at midlife and well-being measured at midlife and approximately 9-years later. (2) Using a subsample of twins, test for heritable variation in social-relational exposures, and (3) controlling for heritable and shared environmental variation, estimate overlap between social-relational exposures and well-being, both concurrently and approximately 9-years later. Results indicated small-to-moderate overlap between exposures and well-being (mean r = 0.29, range = 0.05–0.54). There was also evidence for heritable variation in exposures, and after accounting for these genetic factors, the degree of overlap between social-relational exposures and well-being decreased (mean r = 0.10, range = −0.07 to 0.33).     

The linear system theory's account of behavior maintained by variable-ratio schedules.

The mathematical theory of linear systems, which has been used successfully to describe behavior maintained by variable-interval schedules, is extended to describe behavior maintained by variable-ratio schedules. The result of the analysis is a pair of equations, one of which expresses response rate on a variable-ratio schedule as a function of the mean ratio requirement (n) that the schedule arranges. The other equation expresses response rate on a variable-ratio schedule as a function of reinforcement rate. Both equations accurately describe existing data from variable-ratio schedules. The theory accounts for two additional characteristics of behavior maintained by variable-ratio schedules; namely, the appearance of strained, two-valued (i.e., zero or very rapid) responding at large ns, and the abrupt cessation of responding at a boundary n. The theory also accounts for differences between behavior on variable-interval and variable-ratio schedules, including (a) the occurrence of strained responding on variable-ratio but not on variable-interval schedules, (b) the abrupt cessation of responding on occurrence of higher response rates on variable-ratio than on variable-interval schedules. Furthermore, given data from a series of variable-interval schedules and from a series of concurrent variable-ratio variable-interval schedules, the theory permits quantitative prediction of many properties of behavior on single-alternative variable-ratio schedules. The linear system theory's combined account of behavior on variable-interval and variable-ratio schedules is superior to existing versions of six other mathematical theories of variable-interval and variable-ratio responding.