Motor response inhibition and execution in the stop-signal task: development and relation to ADHD behaviors

Executive functions and child problem behaviors are sensitive to family disruption: a study of children of mothers working overseas

Mothers in Sri Lanka are increasingly seeking overseas employment, resulting in disruption of the childcare environment. The present study was designed to evaluate the effects of maternal migration on executive function (EF) and behavior, thereby also contributing to the scientific understanding of environmental effects--or more specifically family effects--on children's neurocognitive functioning. A sample of 60 healthy 11-year-old children whose mothers had been working overseas for more than 1 year formed the study group, and a comparison group was recruited from the same schools. Evaluations were made twice over a 1-year interval with regard to the EF components inhibition and working memory as well as teacher ratings of internalizing and externalizing behavior. The children in the study group were found to have poorer EF and higher levels of externalizing behaviors. A composite score of inhibition partially mediated the group effect on externalizing behavior. Current home environment was assessed using the HOME scale, was poorer for the study group and was related to EF, but not to behavior problems. Keeping in mind the correlational nature of the present data, our results were discussed in relation to studies showing cognitive effects of stress.

Postnatal brain development: structural imaging of dynamic neurodevelopmental processes

After birth, there is striking biological and functional development of the brain's fiber tracts as well as remodeling of cortical and subcortical structures. Behavioral development in children involves a complex and dynamic set of genetically guided processes by which neural structures interact constantly with the environment. This is a protracted process, beginning in the third week of gestation and continuing into early adulthood. Reviewed here are studies using structural imaging techniques, with a special focus on diffusion weighted imaging, describing age-related brain maturational changes in children and adolescents, as well as studies that link these changes to behavioral differences. Finally, we discuss evidence for effects on the brain of several factors that may play a role in mediating these brain-behavior associations in children, including genetic variation, behavioral interventions, and hormonal variation associated with puberty. At present longitudinal studies are few, and we do not yet know how variability in individual trajectories of biological development in specific neural systems map onto similar variability in behavioral trajectories.