Does ethnic identity buffer or intensify the stress of discrimination among the foreign born and U.S. born? Evidence from the Miami‐Dade Health Survey

This study examines the extent to which ethnic identity is a protective factor and buffers the stress of discrimination among the foreign born compared to the U.S. born in Miami‐Dade County. Data were drawn from the 2011 Miami‐Dade Health Survey (N = 444), which is a countywide probability sample of adults in South Florida. Two interaction effects were observed: (a) a stronger ethnic identity was associated with less distress among the foreign born than the U.S. born; and (b) a stronger ethnic identity exacerbated the relationship between everyday discrimination and distress among the U.S. born. Ethnic identity, which involves ethnic pride, participation in cultural practices, and cultural commitment or sense of belonging, was associated with better psychological well‐being among the foreign born than the U.S. born. Ethnic identity, however, was not a protective factor for the U.S. born, but rather it intensified the distressing effect of discrimination.     

Structural correlates of the orbitofrontal cortex and amygdala and personality in female adolescents

The five‐factor model consists of cognitive‐affective‐behavioral trait dimensions (neuroticism, extraversion, openness to experience, agreeableness, conscientiousness) that are central to models of psychopathology. In adults, individual differences in three of the Big Five traits, neuroticism, extraversion, and conscientiousness, have been linked to structural morphology and connectivity of the orbitofrontal cortex (OFC) and the amygdala, two brain regions critically involved in affective and regulatory processing. It is unclear whether these associations manifest in adolescence, a critical neurodevelopmental period during which many forms of psychiatric illness emerge. A total of 223 adolescent girls (ages 14–16 years) completed a multimodal neuroimaging study that utilized T1‐weighted structural MRI (e.g., cortical thickness and volume) and tractography‐based diffusion tensor imaging (64‐direction). Cortical thickness and volume were extracted from the medial orbitofrontal cortex (mOFC) and amygdala and tractography‐based fractional anisotropy was computed in the uncinate fasciculus (UF; the white matter tract connecting the OFC to the temporal lobe). We found that high neuroticism was associated with less mOFC volume (bilateral), and low conscientiousness was associated with higher white matter integrity in the UF, more amygdala volume, and less mOFC thickness (right hemisphere). Extraversion was not observed to share associations with OFC markers. These OFC‐amygdala structural correlations to personality do not match those reported in adult samples. Multimodal neuroimaging techniques can help to clarify the underpinnings of personality development between adolescence and adulthood.     

Mandible strength and geometry in relation to bite force: a study in three caviomorph rodents

The monophyletic group Caviomorpha constitutes the most diverse rodent clade in terms of locomotion, ecology and diet. Caviomorph species show considerable variation in cranio‐mandibular morphology that has been linked to the differences in toughness of dietary items and other behaviors, such as chisel‐tooth digging. This work assesses the structural strength of the mandible of three caviomorph species that show remarkable differences in ecology, behavior and bite force: Chinchilla lanigera (a surface‐dwelling species), Octodon degus (a semi‐fossorial species) and Ctenomys talarum (a subterranean species). Finite element (FE) models of the mandibles are used to predict the stresses they withstand during incisor biting; the results are related to in vivo bite forces and interspecific variations in the mandibular geometries. The study concludes that the mandible of C. talarum is better able to withstand strong incisor bites. Its powerful adducting musculature is consistent with the notorious lateral expansion of the angular process and the masseteric crest, and the enhanced cortical bone thickness. Although it has a relatively low bite force, the mandible of O. degus also shows a good performance for mid‐to‐strong incisor biting, in contrast to that of C. lanigera, which exhibits, from a mechanical point of view, the worst performance. The mandibles of C. talarum and O. degus appear to be better suited to withstand stronger reaction forces from incisor biting, which is consistent with their closer phylogenetic affinity and shared digging behaviors. The contrast between the low in vivo bite force of C. lanigera and the relatively high estimations that result from the models suggests that its adductor musculature could play significant roles in functions other than incisor biting.