This thesis had two main focuses. First, it investigated the mechanisms underlying individual differences in brain structure, developmental changes, and function. Second, it examined how enriched... Show moreThis thesis had two main focuses. First, it investigated the mechanisms underlying individual differences in brain structure, developmental changes, and function. Second, it examined how enriched and deprived environments affect brain development from middle childhood to early adolescence (ages 7-14). The study revealed distinct genetic and environmental influences on the developing brain during this period. Genetic contributions largely explained the variations in brain structure and developmental changes, along with location-specific environmental factors. While studies on genetic and environmental influences on brain regions showed both overlapping and unique outcomes, the interplay between these influences is complex. Using MRI and fMRI provided a comprehensive understanding of how individual differences arise. Additionally, the thesis highlighted the distinct effects of specific environmental influences on brain development. An enriched cognitive environment, such as musical ability, was linked to attenuated development, while a deprived environment, exemplified by the COVID-19 pandemic, accelerated development. Notably, the brain showed resilience to adverse effects, particularly in TPJ growth during the pandemic, suggesting adaptive processes during this developmental phase. Future research should explore whether the relationship between environmental effects and brain maturation pace is linked to positive mental health outcomes. Ultimately, identifying interventions to ensure all children thrive throughout their development is crucial. Show less