Early childhood is a critical period of brain development, with rapid cognitive, emotional, social, and behavioural changes. Significant gains in language ability occur during early childhood, and are related to future reading success. Reading disabilities affect academic achievement, mental health, and career prospects, so early identification and treatment are critical to improving long-term outcomes. Early interventions tend to be most effective, though accurate identification of reading disabilities is currently not possible until after formal reading instruction has begun. An understanding of the structural brain changes underlying language in early childhood may not only help detect early abnormalities, but may also identify critical periods of plasticity during which interventions may be most effective. Magnetic resonance imaging (MRI) is an excellent way to study in vivo brain development, yet most MRI studies focus on neonates or children school-aged or older, so brain maturation during early childhood remains poorly understood. The objective of this project is to characterize structural brain development in children aged 2-6 years, and to examine the links between this structural maturation and the development of language skills and reading readiness. We will obtain MRI scans and language assessments annually over three years (4 visits total) in preschool children (aged 2-6 years) in order to develop a better understanding of early childhood brain development. We hypothesize that: (i) children with better language ability have more mature brain structure in reading areas (i.e., left temporal-parietal, occipital-temporal, inferior frontal); and (ii) trajectories of longitudinal structural brain development from 2-6 years predict children’s reading readiness at age 5-6 years. Preliminary, cross-sectional imaging data from 14 subjects aged 3-6 years (2-year olds are too young for the language assessments) shows a significant positive correlation between MRI diffusion anisotropy (a measure of white matter integrity) in the posterior corpus callous and phonological processing scores (R=0.56, p=0.037). An additional potentially important relationship was observed between speeded naming and diffusion anisotropy in the inferior longitudinal fasciculus (R=0.49, p=0.089). Our study will develop knowledge and tools to allow for the delivery of interventions to children at risk for reading disabilities, at a time when they will be of greatest benefit. Ultimately, this will significantly improve the long-term academic, health and socioeconomic outcomes of these children and benefit society as a whole.
Brain Development and Language in Preschool Children