Scott K. Holland, Ph.D.
SUMMARY: Dr. Scott Holland discussed his ongoing 5-year functional magnetic resonance imaging (fMRI) study of normal language development in children ages 5 to 18. The study began in 1998 when attempts to investigate the localization of language acquisition to one side of the brain (lateralization) in epileptic children revealed a dearth of information. Dr. Holland first created reference standards for brain activity during language acquisition in normal children. While being scanned, participants performed language tasks designed to contrast vocabulary-processing skills (lexicality) with the ability to form sentences (sentential skills). Finger-tapping tasks were performed as a nonlanguage control task.
Hollandís study population included: (1) a normally developing group of boys and girls at each year of age from 5 to 18; (2) a longitudinal group of 20 children who entered the study at age 7; and (3) 10 children who experienced severe perinatal strokes.
He presented composite brain activation maps and lateralization growth curves for each of the fMRI language tasks and animations showing the evolution of language activation patterns that change as a function of age. These changes closely followed hypotheses about the developmental skill levels required for each task and its content. Results demonstrated that semantic (relating to meaning) and syntactic (rules governing how words are put together to form sentences) skills and the brain areas involved with them continue to develop throughout the age span.
Lastly, preliminary findings in children with severe left hemisphere damage in the language areas were compared with normative composite data. fMRI revealed lateralization variations in brains of epileptic children as a function of age. Differences have also been revealed in brain activation during language tasks in children who had experienced perinatal stroke. Holland concluded that fMRI could also be a valuable tool for following subtle changes in less severe pathologies, such as lead exposure.