Sex matters during adolescence: Testosterone-related cortical thickness maturation differs between boys and girls

Age-related changes in cortical thickness have been observed during adolescence, including thinning in frontal and parietal cortices, and thickening in the lateral temporal lobes. Studies have shown sex differences in hormone-related brain maturation when boys and girls are age-matched, however, because girls mature 1-2 years earlier than boys, these sex differences could be confounded by pubertal maturation. To address puberty effects directly, this study assessed sex differences in testosterone-related cortical maturation by studying 85 boys and girls in a narrow age range and matched on sexual maturity. We expected that testosterone-by-sex interactions on cortical thickness would be observed in brain regions known from the animal literature to be high in androgen receptors. We found sex differences in associations between circulating testosterone and thickness in left inferior parietal lobule, middle temporal gyrus, calcarine sulcus, and right lingual gyrus, all regions known to be high in androgen receptors. Visual areas increased with testosterone in boys, but decreased in girls. All other regions were more impacted by testosterone levels in girls than boys. The regional pattern of sex-by-testosterone interactions may have implications for understanding sex differences in behavior and adolescent-onset neuropsychiatric disorders. © 2012 Bramen et al

Reduced Gray to White Matter Tissue Intensity Contrast in Schizophrenia

BACKGROUND: While numerous structural magnetic resonance imaging (MRI) studies revealed changes of brain volume or density, cortical thickness and fibre integrity in schizophrenia, the effect of tissue alterations on the contrast properties of neural structures has so far remained mostly unexplored. METHODS: Whole brain high-resolution MRI at 3 Tesla was used to investigate tissue contrast and cortical thickness in patients with schizophrenia and healthy controls. RESULTS: Patients showed significantly decreased gray to white matter contrast in large portions throughout the cortical mantle with preponderance in inferior, middle, superior and medial temporal areas as well as in lateral and medial frontal regions. The extent of these intensity contrast changes exceeded the extent of cortical thinning. Further, contrast changes remained significant after controlling for cortical thickness measurements. CONCLUSIONS: Our findings clearly emphasize the presence of schizophrenia related brain tissue changes that alter the imaging properties of brain structures. Intensity contrast measurements might not only serve as a highly sensitive metric but also as a potential indicator of a distinct pathological process that might be independent from volume or thickness alterations

Development of neural correlates of empathy from childhood to early adulthood: An fMRI study in boys and adult men

Greimel E, Schulte-Rüther M, Fink GR, Piefke M, Herpertz-Dahlmann B, Konrad K. Development of neural correlates of empathy from childhood to early adulthood: An fMRI study in boys and adult men. Journal of Neural Transmission. 2010;117(6):781-791

Identity Styles, Positive Youth Development, and Civic Engagement in Adolescence

Identity formation is a core developmental task of adolescence. Adolescents can rely on different social-cognitive styles to seek, process, and encode self-relevant information: information-oriented, normative, and diffuse-avoidant identity styles. The reliance on different styles might impact adolescents' adjustment and their active involvement in the society. The purpose of this study was to examine whether adolescents with different identity styles report differences in positive youth development (analyzed with the Five Cs-Competence, Confidence, Character, Connection, and Caring-model) and in various forms of civic engagement (i.e., involvement in school self-government activities, volunteering activities, youth political organizations, and youth non-political organizations). The participants were 1,633 (54.1 % female) 14-19 years old adolescents (Mage = 16.56, SDage = 1.22). The findings indicated that adolescents with different identity styles differed significantly on all the Five Cs and on two (i.e., involvement in volunteering activities and in youth non-political organizations) forms of civic engagement. Briefly, adolescents with an information-oriented style reported high levels of both the Five Cs and civic engagement; participants with a normative style reported moderate to high scores on the Five Cs but low rates of civic engagement; diffuse-avoidant respondents scored low both on the Five Cs and on civic engagement. These findings suggest that the information-oriented style, contrary to the diffuse-avoidant one, has beneficial effects for both the individual and the community, while the normative style has quite beneficial effects for the individual but not for his/her community. Concluding, adolescents with different identity styles display meaningful differences in positive youth development and in rates of civic engagement

Longitudinal analysis of the developing rhesus monkey brain using magnetic resonance imaging: birth to adulthood

We have longitudinally assessed normative brain growth patterns in naturalistically reared Macaca mulatta monkeys. Postnatal to early adulthood brain development in two cohorts of rhesus monkeys was analyzed using magnetic resonance imaging. Cohort A consisted of 24 rhesus monkeys (12 male, 12 female) and cohort B of 21 monkeys (11 male, 10 female). All subjects were scanned at 1, 4, 8, 13, 26, 39, and 52 weeks; cohort A had additional scans at 156 weeks (3 years) and 260 weeks (5 years). Age-specific segmentation templates were developed for automated volumetric analyses of the T1-weighted magnetic resonance imaging scans. Trajectories of total brain size as well as cerebral and subcortical subdivisions were evaluated over this period. Total brain volume was about 64 % of adult estimates in the 1-week-old monkey. Brain volume of the male subjects was always, on average, larger than the female subjects. While brain volume generally increased between any two imaging time points, there was a transient plateau of brain growth between 26 and 39 weeks in both cohorts of monkeys. The trajectory of enlargement differed across cortical regions with the occipital cortex demonstrating the most idiosyncratic pattern of maturation and the frontal and temporal lobes showing the greatest and most protracted growth. A variety of allometric measurements were also acquired and body weight gain was most closely associated with the rate of brain growth. These findings provide a valuable baseline for the effects of fetal and early postnatal manipulations on the pattern of abnormal brain growth related to neurodevelopmental disorders. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00429-015-1076-x) contains supplementary material, which is available to authorized users