Sex Differences in Social Interaction Behavior Following Social Defeat Stress in the Monogamous California Mouse (Peromyscus californicus)

Stressful life experiences are known to be a precipitating factor for many mental disorders. The social defeat model induces behavioral responses in rodents (e.g. reduced social interaction) that are similar to behavioral patterns associated with mood disorders. The model has contributed to the discovery of novel mechanisms regulating behavioral responses to stress, but its utility has been largely limited to males. This is disadvantageous because most mood disorders have a higher incidence in women versus men. Male and female California mice (Peromyscus californicus) aggressively defend territories, which allowed us to observe the effects of social defeat in both sexes. In two experiments, mice were exposed to three social defeat or control episodes. Mice were then behaviorally phenotyped, and indirect markers of brain activity and corticosterone responses to a novel social stimulus were assessed. Sex differences in behavioral responses to social stress were long lasting (4 wks). Social defeat reduced social interaction responses in females but not males. In females, social defeat induced an increase in the number of phosphorylated CREB positive cells in the nucleus accumbens shell after exposure to a novel social stimulus. This effect of defeat was not observed in males. The effects of defeat in females were limited to social contexts, as there were no differences in exploratory behavior in the open field or light-dark box test. These data suggest that California mice could be a useful model for studying sex differences in behavioral responses to stress, particularly in neurobiological mechanisms that are involved with the regulation of social behavior

Responses to dominance challenge are a function of psychopathy level:A multimethod study

This study assesses the relationship between psychopathy and dominance, both as a trait level and in 2 interpersonal contexts. Following the interpersonal circumplex model, we expected that interacting with a dominant interviewer would reduce dominance displays by low psychopathy participants (interpersonal complementarity) but might increase such displays in those with higher psychopathy (anticomplementarity). Psychopathic traits and dominance were assessed in a community sample (N = 91) using multiple dominance indicators: self-reported overall dominance level, job preference, dominance displays observed during identical interviews with a subordinate and dominant interviewer, and baseline and postinterview measures of personal space and testosterone level. Psychopathic traits were positively related to dominance on both trait measures and in the interviews. As a trait, higher self-reported psychopathy scores were associated with higher levels of self-reported dominance and preference for supervisory job positions. Higher Factor 1 psychopathy scores were associated with increased dominance display in interaction with the dominant interviewer. Higher Factor 2 scores were associated with allowing the dominant interviewer to approach more closely (reduced physical distancing). Psychopathy was partly related to a delayed increase in testosterone levels after interaction. Psychopathic traits may include a general tendency to dominate, a tendency which increases when interacting with a dominant other. The emotional/interpersonal psychopathy factor is specifically related to increased dominance displays when interacting with a dominant individual, while the behavioral factor of psychopathy is related to reduced physical distancing of a dominant partner. At higher psychopathy levels the general rule of dominant-subordinate reciprocity during social interaction is reversed

Tantrums, Emotion Reactions and Their EEG Correlates in Childhood Benign Rolandic Epilepsy vs. Complex Partial Seizures: Exploratory Observations

We explored associations between EEG pathophysiology and emotional/behavioral (E/B) problems of children with two types of epilepsy using standard parent questionnaires and two new indicators: tantrums recorded by parents at home and brief, emotion-eliciting situations in the laboratory. Children with Benign Rolandic epilepsy (BRE, N = 6) reportedly had shorter, more angry tantrums from which they recovered quickly. Children with Complex Partial Seizures (CPS, N = 13) had longer, sadder tantrums often followed by bad moods. More generally, BRE correlated with anger and aggression; CPS with sadness and withdrawal. Scores of a composite group of siblings (N = 11) were generally intermediate between the BRE and CPS groups. Across all children, high voltage theta and/or interictal epileptiform discharges (IEDs) correlated with negative emotional reactions. Such EEG abnormalities in left hemisphere correlated with greater social fear, right hemisphere EEG abnormalities with greater anger. Right hemisphere localization in CPS was also associated with parent-reported problems at home. If epilepsy alters neural circuitry thereby increasing negative emotions, additional assessment of anti-epileptic drug treatment of epilepsy-related E/B problems would be warranted