Acute stress or systemic insulin injection increases flunitrazepam sensitive-GABAA receptor density in synaptosomes of chick forebrain: Modulation by systemic epinephrine

Interactions between acute stress and systemic insulin and epinephrine on GABAA receptor density in the forebrain were studied. Here, 10 day-old chicks were intraperitoneally injected with insulin, epinephrine or vehicle and then immediately stressed by partial water immersion for 15 min and killed by decapitation. Non-stressed controls were similarly injected, then returned to their rearing boxes for 15 min and then killed. Forebrains were dissected and GABAA receptor density was measured ex vivo in synaptosomes by 3[H]-flunitrazepam binding assay. In non-stressed chicks, insulin at 1.25, 2.50 and 5.00 IU/kg of body weight (non-hypoglycemic doses) increased Bmax by 33, 53 and 44% compared to saline, respectively. A similar increase of 41% was observed in receptor density after stress. However, the insulin effect was not additive to the stress-induced increase suggesting that both effects occur through similar mechanisms. In contrast, epinephrine, at 0.25 and 0.5 mg/kg did not induce any changes in Bmax in non-stressed chicks. Nevertheless, after stress these doses increased the receptor density by about 13 and 27%, respectively. Similarly, the same epinephrine doses co-administered with insulin (2.50 IU/kg), increased the receptor density by about 20% compared to insulin alone. These results suggest that systemic epinephrine, perhaps by evoking central norepinephrine release, modulates the increase in forebrain GABAA receptor binding induced by both insulin and stress.     

Effect of a positive emotional state on interpretation bias for threat in children with anxiety disorders

The authors examined the effect of a positive emotional state on interpretation bias for threat in children with anxiety disorders. Participants were 34 children with anxiety disorders and 34 children without any psychological disorders who were randomly assigned to either a positive or neutral emotion induction condition. Consistent with the broaden-and-build theory, children with anxiety disorders exhibited an interpretation bias for threat, but not when they were in a positive emotional state. Furthermore, results indicated that positive emotional state made a unique prediction of interpretation bias score, whereas state anxiety did not. Findings are discussed with reference to theory, clinical implications, and suggestions for future research.     

Physical and psychological aggression in dating relationships in Spanish university students

The presence of violent behaviors of a psychological and physical nature in dating relations was analyzed in a sample of Spanish university students between 18 and 27 years of age. The results indicate a high prevalence of both kinds of aggression in interpersonal relationships, revealing important typology differences between the sexes. Violent psychological behaviors (characterized by the presence of verbal aggression and coercive and jealous behaviors) and physical aggression were significantly higher in women, though the consequences of physical aggression were worse for the women's health. The implications of the results and their possible relation with more severe violent acts in more stable, emotional relationships are discussed.     

The effects of young children's affiliations with prosocial peers on subsequent emotionality in peer interactions

Preschoolers’ (60 boys and 64 girls, M age = 50.73 months) affiliations with prosocial peers were observed in naturally occurring interactions and then examined in relation to positive and negative emotionality within their peer interactions one semester later. Greater affiliation with prosocial peers in the fall was related to enhanced positive emotionality (especially for girls) and decreased negative emotionality (especially for boys) in later peer interactions. These findings held when initial levels of the emotion were controlled and were found above and beyond variations in classroom levels of prosociality. The findings suggest that peers exert influence in early childhood and that these effects can positively affect the quality of young children's later peer interactions.     

Exploring task-set reconfiguration with random task sequences

Switching between two different tasks normally results in an impairment in people's performance known as a switch cost, typically measured as an increase in reaction time (RT) and errors compared to a situation in which no task switch is required. Researchers in task switching have suggested that this switch cost is the behavioural manifestation of the task set reconfiguration processes that are necessary to perform the upcoming task. However, an examination of the literature in task switching reveals apparently contradictory results about the nature of task set reconfiguration processes. In Experiment 1, we addressed this issue by comparing participants' performance in two different experimental conditions: predictable task switching and random task switching. In the predictable switch condition the switch cost completely vanished after the first repetition of the new task. However, in the random switch condition, while the difference between switch and repetition trials was not significant, we observed a significant reduction in RT between the first and second repetition of the new task. In Experiment 2, we further investigated the pattern of task set reconfiguration in the random switch situation. The results showed a progressive reduction of participants' response latencies across repetitions of the same task. The present study demonstrates that, whereas the results in predictable switching conditions are compatible with an exogenous-reconfiguration hypothesis, random task switching produces a more gradual, decay-like switch cost reduction with task repetition.