Stress induces glucocorticoid-mediated apoptosis of rat Leydig cells in vivo

Stress can disrupt endocrine signalling in the male reproductive axis through high concentrations of glucocorticoids, the hallmark of stress. Our previous work revealed that a stress level of exogenous glucocorticoids could induce apoptosis of rat Leydig cells, which are the primary source of testosterone. The aim of this study was to investigate whether stress can induce apoptosis in rat Leydig cells in vivo and, if so, whether the process is the result of a direct effect of glucocorticoids. In a chronically stressed rat model, serum corticosterone concentration was increased significantly whereas serum testosterone was decreased. The frequency of apoptotic Leydig cells in stressed rats was also increased. Adrenalectomised rats subjected to chronic stress showed an elevated serum testosterone, while the apoptotic frequency of Leydig cells was not increased. It was established that glucocorticoid-induced Leydig cell apoptosis is mediated by glucocorticoid receptors (GRs), which translocate from cytoplasm to nucleus. Adenovirus microRNA-induced downregulation of GR expression in vitro alleviated the corticosterone-induced increase in apoptosis of Leydig cells. These results indicate that the stress-induced increase in corticosterone secretion resulted in apoptosis in rat Leydig cells in vivo, and thereby decreased testosterone synthesis.     

Active coping with stress suppresses glucose metabolism in the rat hypothalamus

We used 18F-fluorodeoxyglucose small-animal positron-emission tomography to determine whether different styles of coping with stress are associated with different patterns of neuronal activity in the hypothalamus. Adult rats were subjected to immobilization (IMO)-stress or to a non-immobilized condition for 30 min, in random order on separate days, each of which was followed by brain-scanning. Some rats in the immobilized condition were allowed to actively cope with the stress by chewing a wooden stick during IMO, while the other immobilized rats were given nothing to chew on. Voxel-based statistical analysis of the brain imaging data shows that chewing counteracted the stress-induced increased glucose uptake in the hypothalamus to the level of the non-immobilized condition. Region-of-interest analysis of the glucose uptake values further showed that chewing significantly suppressed stress-induced increased glucose uptake in the paraventricular hypothalamic nucleus and the anterior hypothalamic area but not in the lateral hypothalamus. Together with the finding that the mean plasma corticosterone concentration at the termination of the IMO was also significantly suppressed when rats had an opportunity to chew a wooden stick, our results showed that active coping by chewing inhibited the activation of the hypothalamic-pituitary-adrenal axis to reduce the endocrine stress response.     

An associative model of adaptive inference for learning word-referent mappings

People can learn word–referent pairs over a short series of individually ambiguous situations containing multiple words and referents (Yu & Smith, 2007, Cognition 106: 1558–1568). Cross-situational statistical learning relies on the repeated co-occurrence of words with their intended referents, but simple co-occurrence counts cannot explain the findings. Mutual exclusivity (ME: an assumption of one-to-one mappings) can reduce ambiguity by leveraging prior experience to restrict the number of word–referent pairings considered but can also block learning of non-one-to-one mappings. The present study first trained learners on one-to-one mappings with varying numbers of repetitions. In late training, a new set of word–referent pairs were introduced alongside pretrained pairs; each pretrained pair consistently appeared with a new pair. Results indicate that (1) learners quickly infer new pairs in late training on the basis of their knowledge of pretrained pairs, exhibiting ME; and (2) learners also adaptively relax the ME bias and learn two-to-two mappings involving both pretrained and new words and objects. We present an associative model that accounts for both results using competing familiarity and uncertainty biases.     

A latent profile analysis of Asian American men's and women's adherence to cultural values

The goal of this study was to identify diverse profiles of Asian American women's and men's adherence to values that are salient in Asian cultures (i.e., conformity to norms, family recognition through achievement, emotional self-control, collectivism, and humility). To this end, the authors conducted a latent profile analysis using the 5 subscales of the Asian American Values Scale-Multidimensional in a sample of 214 Asian Americans. The analysis uncovered a four-cluster solution. In general, Clusters 1 and 2 were characterized by relatively low and moderate levels of adherence to the 5 dimensions of cultural values, respectively. Cluster 3 was characterized by the highest level of adherence to the cultural value of family recognition through achievement, whereas Cluster 4 was typified by the highest levels of adherence to collectivism, emotional self-control, and humility. Clusters 3 and 4 were associated with higher levels of depressive symptoms than Cluster 1. Furthermore, Asian American women and Asian American men had lower odds of being in Cluster 4 and Cluster 3, respectively. These findings attest to the importance of identifying specific patterns of adherence to cultural values when examining the relationship between Asian Americans' cultural orientation and mental health status.     

The nonlinear effects of conscientiousness on overall job performance and performance dimensions in the Chinese context

The relationship between conscientiousness and job performance has been found to be nonlinear in the West, which challenges conceptually and empirically the traditional assumption of the single linear relationship. In this research, we examined the nonlinear effects of conscientiousness on both overall job performance and performance dimensions (i.e., task performance, adaptive performance and contextual performance) in the Chinese context. The results of our two studies supported some evidence for the nonlinear effect of conscientiousness on overall job performance. In addition, it was found that conscientiousness has different (linear or nonlinear) effects on performance dimensions. These findings suggest that the nonlinear effects of conscientiousness on job performance deserve further investigation, and a distinction should be made with regard to job performance in personnel evaluation. Results are discussed in terms of the significance of considering the nonlinear relationship between conscientiousness and performance criteria.     

Unpacking Cultural Variations in Peak-Experiences: Cross-Cultural Comparisons of Early Childhood Recollection Between Hong Kong and Brazil

In this cross-cultural study, 115 Hong Kong Chinese and 117 Brazilian college students described a childhood peak-experience (occurring before the age of 14) and provided a self-rating on its enduring impact. Among various categories of peak-experiences, both Hong Kong Chinese and Brazilians reported interpersonal joy most frequently; the second most frequently reported category was external achievement for the Hong Kong sample and developmental landmark for the Brazilian sample. Compared with Brazilians’ narratives, those of Hong Kong Chinese were more social-focused, involving greater number of other people, but less specific. These characteristics of autobiographical memory, i.e., memory focus (self vs. social), memory specificity (specific vs. general), and the number of other people involved, significantly mediated the relation between culture and interpersonal joy. The present findings have extended research on peak-experiences to cross-cultural contexts and incorporated measures of autobiographical memory to unpack cultural variations in these two collectivist societies.     

Overall Hedonic Evaluations and Evaluation of Specific Moments from Past Relationships and High School Days

Two studies were conducted in which student participants gave overall hedonic evaluations of past relationships or their high school days, and, additionally, gave similar evaluations of the best, most memorable, worst, initial, and final moments from them. They also evaluated a typical moment and the percentages of good and bad times in these experiences. Such results from some individuals were given to other participants, who were also asked to make overall evaluations. Overall, the overall evaluations of the original participant related weakly rather than strongly to the evaluations of the specific moments. Generally, the other participants’ overall evaluations converged on those of the original recalling participants, but their overall evaluations of the past relationships were more positive than either their own initial evaluations or those of the original, recalling respondents. In sum, overall evaluations of these long, diverse experiences were not well predicted from valuations of the specific moments we investigated. Hedonic evaluations of past experiences may be influenced by appraisals of their success.     

Wild bearded capuchin (Sapajus libidinosus) select hammer tools on the basis of both stone mass and distance from the anvil

Contemporary optimization models suggest that animals optimize benefits of foraging and minimize its costs. For wild bearded capuchins (Sapajus libidinosus), nut-cracking entails cost related to lifting the heavy stone and striking the nut and additional cost to transport the stone if it is not already on the anvil. To assess the role of stone mass and transport distance in capuchins’ tool selection, we carried out three field experiments. In Experiment 1, we investigated whether transport distance affected choice of a tool by positioning two stones of the same mass close and far from the anvil. Capuchins consistently selected the closer stone, effectively reducing transport costs. In Experiment 2, we examined the trade-off between the cost of transport and the effectiveness in cracking by positioning two stones of different mass close and far from the anvil. Most subjects significantly preferred the closer stone, regardless of mass, whereas others preferred the heavier stone regardless of transport distance. In Experiment 3, we changed transport distance of both stones while maintaining the same distance ratios as in Experiment 2. Capuchins maintained the preferences expressed in Experiment 2, with the exception of one subject. Overall, our findings indicate that (1) individuals vary in their sensitivity to distance of transport, (2) a few meters are perceived as a substantive cost by some monkeys, and (3) monkeys’ body mass affects their decisions. We also developed a non-dimensional Preference index (P) defined as a function of the stone mass and the transport distance to describe monkey’s choice.     

Customer reactions to encountering consecutive service failures

According to previous studies, many consumers in Taiwan have experienced consecutive service failures. Despite these failures, many consumers still remain loyal to a service provider for a variety of reasons, such as money deposits, contractual agreements, associated costs, time constrains, and health concerns. We attempt to investigate the emotional reactions and expectations of consumers after they have experienced two consecutive service failures. Our findings reveal that for high‐involvement services, although customers display strong negative emotional reactions after each service failure, the reaction to the second service failure is less intensive than that to the first one. Furthermore, our findings show that as long as the products or services remain in use, customers tend to retain high levels of expectation in regard to the service provider. Copyright © 2012 John Wiley & Sons, Ltd.     

Heartwarming memories: Nostalgia maintains physiological comfort

Nostalgia, a sentimental longing or wistful affection for the past, is a predominantly positive and social emotion. Recent evidence suggests that nostalgia maintains psychological comfort. Here, we propose, and document in five methodologically diverse studies, a broader homeostatic function for nostalgia that also encompasses the maintenance of physiological comfort. We show that nostalgia--an emotion with a strong connotation of warmth--is triggered by coldness. Participants reported stronger nostalgia on colder (vs. warmer) days and in a cold (vs. neutral or warm) room. Nostalgia, in turn, modulates the interoceptive feeling of temperature. Higher levels of music-evoked nostalgia predicted increased physical warmth, and participants who recalled a nostalgic (vs. ordinary autobiographical) event perceived ambient temperature as higher. Finally, and consistent with the close central nervous system integration of temperature and pain sensations, participants who recalled a nostalgic (vs. ordinary autobiographical) event evinced greater tolerance to noxious cold.