Stress and cardiac beta adrenoceptors

Most modern theories about stress recognize that although stress is not a disease, it may be the trigger for the majority of diseases when allostatic overload has been generated. During stress, the glucocorticoids and catecholamines play a key role in the regulation of physiological parameters and homeostasis during stress. In the heart, positive chronotropic, inotropic, and lusitropic responses to catecholamines are mediated by various subtypes of adrenergic receptors (beta-ARs), mainly beta1- and beta2-adrenergic receptors. beta-ARs also control cardiomyocyte growth and death, thus contributing to cardiac remodelling. The structural basis of each beta-AR subtype, as well as their signalling pathways, and adaptive responses to stress are discussed. The participation of beta3- and putative beta4-ARs in the control of cardiac function is also discussed, with emphasis on low affinity beta-AR isoforms and the role they play in the response to the catecholamines under stress. The changes in beta-AR signalling under pathogenic conditions as well as under stress are reviewed.     

The association of macro- and microstructure of the corpus callosum and language lateralisation

The present study aimed to examine how differences in functional lateralisation of language are related to interindividual variations in interhemispheric connectivity. Utilising an fMRI silent word-generation paradigm, 89 left- and right-handed subjects were subdivided into four lateralisation subgroups. Applying morphological and diffusion-tensor MRI, midsagittal cross-sectional area as well as quantitative measures of molecular diffusion (anisotropy, mean diffusion) of the corpus callosum were determined to assess interhemispheric connectivity. Statistical analyses revealed group differences in molecular diffusion but not in callosal size, which may be interpreted to reflect a stronger and/or faster interhemispheric connection in strongly left-lateralised subjects as compared to moderately left-lateralised, bilateral, or moderately right-lateralised subjects.     

Stereotypes: static abstractions or dynamic knowledge structures?

Stereotypes have been assumed to be long-lasting knowledge structures that persist even in the face of contrary evidence. However, there is almost no within-participant research relevant to this assumption. The authors describe 4 studies (N=267), the first 3 of which assessed within-participant stereotype stability over a few weeks with measures of stereotypic trait verification, typicality ratings of exemplar sets, and exemplar retrieval. In the 4th study, the authors manipulated context stability. Overall, results showed only low-to-moderate stereotype stability. The stability obtained was a function of the perceived centrality of traits or exemplars and of context constancy. The authors discuss the implications of these results for abstractionist, exemplar, mixed, and connectionist models and identify possible mechanisms that underlie within-participant stereotype instability.     

Cross-cultural differences for three visual memory tasks in Brazilian children

Norms for three visual memory tasks, including Corsi's block tapping test and the BEM 144 complex figures and visual recognition, were developed for neuropsychological assessment in Brazilian children. The tasks were measured in 127 children ages 7 to 10 years from rural and urban areas of the States of S?o Paulo and Minas Gerais. Analysis indicated age-related but not sex-related differences. A cross-cultural effect was observed in relation to copying and recall of Complex pictures. Different performances between rural and urban children were noted.     

Na+,K(+)-ATPase activity is reduced in hippocampus of rats submitted to an experimental model of depression: effect of chronic lithium treatment and possible involvement in learning deficits

This study was undertaken to verify the effects of chronic stress and lithium treatments on the hippocampal Na+,K(+)-ATPase activity of rats, as well as to investigate the effects of stress interruption and post-stress lithium treatment on this enzyme activity and on spatial memory. Two experiments were carried out; in the first experiment, adult male Wistar rats were divided into two groups: control and submitted to a chronic variate stress paradigm, and subdivided into treated or not with LiCl. After 40 days of treatment, rats were killed, and Na+,K(+)-ATPase activity was determined. In the second experiment, rats were stressed during 40 days, and their performance was evaluated in the Water Maze task. The stressed group was then subdivided into four groups, with continued or interrupted stress treatment and treated or not with lithium for 30 additional days. After a second evaluation of performance in the Water Maze, rats were killed and Na+,K(+)-ATPase activity was also measured. Results showed an impairment in Na+,K(+)-ATPase activity and in Water Maze performance of chronically stressed rats, which were prevented by lithium treatment and reversed by lithium treatment and by stress interruption. These results suggest that the modulation of Na+,K(+)-ATPase activity may be one of the mechanisms of action of lithium in the treatment of mood disorders.     

Why do we share aggressive online content? Testing a short cycle model

The present study aimed to observe the impacts of aggressive online content exposure and personality on aggressive content sharing, considering the mediating role of positive and negative affects. A total of 302 Brazilians, equally divided into two groups, participated in a social network simulation, being exposed to aggressive (experimental group) or neutral (control group) posts and choosing what they would like to share on this site (among aggressive or nonaggressive material). A factorial MANOVA showed a significant difference for positive and negative affects and aggressive content sharing (Wilks' Λ = 0.936; F[3, 298] = 6.812; p = .001; η² = 0.064). Through structural equation modeling, an explanatory model was also tested, in which this behavior was directly predicted by aggressive online content exposure and suffered indirect effects from openness, conscientiousness, and extroversion, mediated by positive affects (goodness-of-fit index = 0.997, comparative fit-index = 0.998, Tucker-Lewis index = 0.996, SRMR = 0.028, root-mean-square error of approximation = 0.035, CI = 0.003−0.054). It is possible to conclude that the objectives are met, highlighting the contribution to understanding aggressive online behavior through the proximal processes described in the general aggression model.     

Social context shapes cognitive abilities: associative memories are modulated by fight outcome and social isolation in the crab Neohelice granulata

Animal Cognition - Cognitive abilities of an animal can be influenced by distinct social experiences. However, the extent of this modulation has not been addressed in different learning scenarios:...     

Implicit open-mindedness: Evidence for and limits on stereotype malleability

Although stereotypes have traditionally been regarded as stable, research has documented their considerable malleability. One potential source of such malleability is intrusion into the stereotype of other concepts also activated when the stereotype is activated. In three experiments we assessed the extent to which stereotypes were influenced by stereotypic, stereotype-unrelated, or counter-stereotypic traits activated in a completely unrelated context immediately prior to stereotype measurement. Across experiments, priming of stereotype-unrelated traits increased their inclusion in the stereotype, whereas priming of counter-stereotypic traits had no effect in the subsequently assessed stereotype. In Experiment 3 we collected perceived dispersion measures and showed that although priming counter-stereotypic traits had no effect on overall characterization of the target group, it boosted perceptions of the group's variability. We accounted for these results by extending Higgins' (1989) Synapse Model of knowledge accessibility to the stereotype domain.