| Structural brain changes occur in a complex manner throughout life, and understanding healthy brain development is crucial for the study of brain abnormalities in various conditions. Diffusion tensor imaging (DTI) is an advanced magnetic resonance imaging technique that provides information about tissue microstructure not accessible via conventional imaging methods. In this dissertation, DTI is used to assess typical brain development, brain abnormalities in fetal alcohol spectrum disorder (FASD), and relationships between cognition and brain structure in both populations.;DTI was also used to examine brain abnormalities in children with FASD, an acquired brain disorder associated with numerous cognitive, behavioural, and emotional difficulties. DTI revealed widespread differences in children with FASD when compared to healthy controls, suggesting extensive structural brain damage.;Finally, significant relationships between cognitive abilities and brain structure were observed in both populations. Brain lateralization of a frontal temporal pathway correlated with two specific cognitive abilities in typically-developing children. Additionally, a significant relationship between brain structure and mathematical ability was observed in the left parietal lobe of children with FASD. Preliminary results demonstrating reading-brain structure correlations in both healthy and FASD groups are also presented.;In conclusion, DTI has shown significant age-related changes in the typically-developing human brain, abnormalities in children with FASD, and correlations between brain structure and cognition in both populations. Normative DTI studies such as the ones presented here are important to establish healthy milestones of brain development and degradation, which may then be used to understand abnormalities in a variety of conditions, including FASD.;Cross-sectional and longitudinal DTI studies were used to measure brain maturation from childhood to adulthood. Significant, nonlinear changes of diffusion parameters were noted across the brain, with regional variation in the timing and magnitude of development. Most regions experienced rapid maturation during childhood and adolescence, reached a developmental peak during adulthood, and then, during senescence, underwent a reversal of structural changes that occurred more gradually than the initial development. The genu and splenium of the corpus callosum had the earliest development, while frontal-temporal connections and the corticospinal tracts showed the most prolonged maturation trajectories. |
