Subcortical volumes across the lifespan: data from 18,605 healthy individuals aged 3-90 years

Age has a major effect on brain volume. However, the normative studies available are constrained by small sample sizes, restricted age coverage and significant methodological variability. These limitations introduce inconsistencies and may obscure or distort the lifespan trajectories of brain morphometry. In response, we capitalized on the resources of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to examine age-related trajectories inferred from cross-sectional measures of the ventricles, the basal ganglia (caudate, putamen, pallidum, and nucleus accumbens), the thalamus, hippocampus and amygdala using magnetic resonance imaging data obtained from 18,605 individuals aged 3-90 years. All subcortical structure volumes were at their maximum value early in life. The volume of the basal ganglia showed a monotonic negative association with age thereafter; there was no significant association between age and the volumes of the thalamus, amygdala and the hippocampus (with some degree of decline in thalamus) until the sixth decade of life after which they also showed a steep negative association with age. The lateral ventricles showed continuous enlargement throughout the lifespan. Age was positively associated with inter-individual variability in the hippocampus and amygdala and the lateral ventricles. These results were robust to potential confounders and could be used to examine the functional significance of deviations from typical age-related morphometric patterns.Education and Child Studie

Entrepreneurial social capital: conceptualizing social capital in new hi-tech firms

Although the literature on social capital has increased dramatically in recent years, concerns have been raised about the expanse of applications of the term, diversity of constructs, definitions and variety of analyses. The purpose of this article is to clarify the conceptualization of social capital in entrepreneurship. To achieve this, the article begins with a review of the extensive literature on social capital. This provides a preliminary theoretical framework about the nature and categories of social capital. Thereafter, an account is provided of an empirical study in which in-depth and extensive data were gathered about the social interactions of entrepreneurs from 10 technology firms. Findings demonstrate that social capital is a social relational artefact produced in social interactions. It is not owned but represents a pool of goodwill residing in a social network and it can be envisaged as a revolving mutual fund of traded and un-traded interdependencies