Investigations of HPA function and the enduring consequences of stressors in adolescence in animal models

Developmental differences in hypothalamic–pituitary–adrenal (HPA) axis responsiveness to stressors and ongoing development of glucocorticoid-sensitive brain regions in adolescence suggest that similar to the neonatal period of ontogeny, adolescence may also be a sensitive period for programming effects of stressors on the central nervous system. Although research on this period of life is scarce compared to early life and adulthood, the available research indicates that effects of stress exposure during adolescence differ from, and may be longer-lasting than, effects of the same stress exposure in adulthood. Research progress in animal models in this field is reviewed including HPA function and the enduring effects of stress exposures in adolescence on sensitivity to drugs of abuse, learning and memory, and emotional behaviour in adulthood. The effects of adolescent stress depend on a number of factors, including the age, gender, the duration of stress exposure, the type of stressor, and the time between stress exposure and testing.     

Mapping gray matter development: Implications for typical development and vulnerability to psychopathology

Recent studies with brain magnetic resonance imaging (MRI) have scanned large numbers of children and adolescents repeatedly over time, as their brains develop, tracking volumetric changes in gray and white matter in remarkable detail. Focusing on gray matter changes specifically, here we explain how earlier studies using lobar volumes of specific anatomical regions showed how different lobes of the brain matured at different rates. With the advent of more sophisticated brain mapping methods, it became possible to chart the dynamic trajectory of cortical maturation using detailed 3D and 4D (dynamic) models, showing spreading waves of changes evolving through the cortex. This led to a variety of time-lapse films revealing characteristic deviations from normal development in schizophrenia, bipolar illness, and even in siblings at genetic risk for these disorders. We describe how these methods have helped clarify how cortical development relates to cognitive performance, functional recovery or decline in illness, and ongoing myelination processes. These time-lapse maps have also been used to study effects of genotype and medication on cortical maturation, presenting a powerful framework to study factors that influence the developing brain.     

Sex differences in the adolescent brain

Adolescence is a time of increased divergence between males and females in physical characteristics, behavior, and risk for psychopathology. Here we will review data regarding sex differences in brain structure and function during this period of the lifespan. The most consistent sex difference in brain morphometry is the 9–12% larger brain size that has been reported in males. Individual brain regions that have most consistently been reported as different in males and females include the basal ganglia, hippocampus, and amygdala. Diffusion tensor imaging and magnetization transfer imaging studies have also shown sex differences in white matter development during adolescence. Functional imaging studies have shown different patterns of activation without differences in performance, suggesting male and female brains may use slightly different strategies for achieving similar cognitive abilities. Longitudinal studies have shown sex differences in the trajectory of brain development, with females reaching peak values of brain volumes earlier than males. Although compelling, these sex differences are present as group averages and should not be taken as indicative of relative capacities of males or females.     

Interactions of space and language: Insights from the neglect syndrome

The current article speculates about the interrelations between space and language from the perspective of the neglect syndrome. Various conflicting findings are reviewed and the effect of cultural factors is strongly emphasised. Current scientific literature describes relationships between space and language; however, the available data render it difficult to conclude whether it is the primacy of spatial representations or the complex two‐way interaction between linguistic and spatial representations that determines the nature of cognitive processing. It is hoped that studying the neglect syndrome will provide a solution to this problem. Finally, directions for future research are provided that requires bridging the gap between cognitive theorising and neuroscientific approaches.     

Common features of fluency-evoking conditions studied in stuttering subjects and controls: an H2O PET study

We used H₂¹⁵O PET to characterize the common features of two successful but markedly different fluency-evoking conditions — paced speech and singing — in order to identify brain mechanisms that enable fluent speech in people who stutter. To do so, we compared responses under fluency-evoking conditions with responses elicited by tasks that typically elicit dysfluent speech (quantifying the degree of stuttering and using this measure as a confounding covariate in our analyses). We evaluated task-related activations in both stuttering subjects and age- and gender-matched controls.

Areas that were either uniquely activated during fluency-evoking conditions, or in which the magnitude of activation was significantly greater during fluency-evoking than dysfluency-evoking tasks included auditory association areas that process speech and voice and motor regions related to control of the larynx and oral articulators. This suggests that a common fluency-evoking mechanism might relate to more effective coupling of auditory and motor systems — that is, more efficient self-monitoring, allowing motor areas to more effectively modify speech.

These effects were seen in both PWS and controls, suggesting that they are due to the sensorimotor or cognitive demands of the fluency-evoking tasks themselves. While responses seen in both groups were bilateral, however, the fluency-evoking tasks elicited more robust activation of auditory and motor regions within the left hemisphere of stuttering subjects, suggesting a role for the left hemisphere in compensatory processes that enable fluency.

Educational objectives: The reader will learn about and be able to: (1) compare brain activation patterns under fluency- and dysfluency-evoking conditions in stuttering and control subjects; (2) appraise the common features, both central and peripheral, of fluency-evoking conditions; and (3) discuss ways in which neuroimaging methods can be used to understand the pathophysiology of stuttering.     

Where in the brain is the self?

Localizing the self in the brain has been the goal of consciousness research for centuries. Recently, there has been an increase in attention to the localization of the self. Here we present data from patients suffering from a loss of self in an attempt to understand the neural correlates of consciousness. Focusing on delusional misidentification syndrome (DMS), we find that frontal regions, as well as the right hemisphere appear to play a significant role in DMS and DMS related disorders. These data are placed in the context of neuroimaging findings.     

Cross‐cultural evidence of value structures and priorities in childhood

We broaden the developmental focus of the theory of universals in basic human values (Schwartz, 1992, Advances in Experimental Social Psychology) by presenting supportive evidence on children's values from six countries: Germany, Italy, Poland, Bulgaria, the United States, and New Zealand. 3,088 7–11‐year‐old children completed the Picture‐Based Value Survey for Children (PBVS‐C, Döring et al., 2010, J. Pers. Assess., 92, 439). Grade 5 children also completed the Portrait Values Questionnaire (PVQ, Schwartz, 2003, A proposal for measuring value orientations across nations. Chapter 7 in the Questionnaire Development Package of the European Social Survey). Findings reveal that the broad value structures, sex differences in value priorities and pan‐cultural value hierarchies typical of adults have already taken form at this early age. We discuss the conceptual implications of these findings for the new field of children's basic values by embedding them in the recent developmental literature.     

Core structure of a〈100〉 superdislocations in a single-crystal superalloy during high-temperature and low-stress creep

A thorough TEM analysis has been carried out to study the dislocations cutting into γ′ phase in a single-crystal superalloy during uniaxial tensile creep under high-temperature and low-stress conditions. It is proved that the a〈100〉 edge superdislocation originates from the interfacial a〈100〉 dislocations and moves into the γ′ phase by pure climbing. And the dissociation of the a〈100〉 superdislocation core into two a/2〈101〉 superpartial dislocations during uniaxial tensile creep has been identified by HRTEM method for the first time.     

Angel or demon? Self-monitoring differences in the mental representations of current versus former romantic partners

We investigated whether high and low self-monitors had (a) segregated/integrated and (b) uniformly favorable (angelic)/uniformly unfavorable (demonic) mental representations of actual romantic partners. Self-monitoring was assessed using the 25-item Self-Monitoring Scale and the structure of mental representations was calculated using a modified segregation/integration measure. In Study 1, low self-monitors were more likely than high self-monitors to have (a) segregated and (b) disproportionally favorable mental representations of their current romantic partners. In Study 2, low self-monitors were more likely than high self-monitors to have (a) segregated and (b) generally unfavorable mental representations of their former romantic partners. Self-monitoring differences were not moderated in either study by relationship longevity or conflict.