Human language development has been studied using behavioral methods for decades, yet the neurobiologic basis of this major childhood accomplishment is not well understood. Mapping the functional distribution of language in the brain throughout normal development could provide considerable insight into the nature of both normal language acquisition and disorders that disrupt language in pediatric populations. Clinically, language is one of the earliest markers for developmental or acquired pediatric neurologic disorders. In children, assessment of language dysfunction must also take into account normal developmental changes that may exist. Functional magnetic resonance imaging (fMRI) offers a noninvasive technique which could be applied to the study of language development. Whereas fMRI has been used to examine language and language pathology in adults, applications of this technology in children have been limited. This is due in part to the inherently low signal-to- noise ratio and sensitivity to motion of fMRI. However, with the use of a 3 Tesla MRI scanner and an experienced pediatric neuroimaging team, we are able to routinely obtain high quality fMRI language maps in children as young as five years of age. We propose to use fMRI techniques at 3 Tesla to map specific aspects of normal language development in children from ages 5 to 18. We will examine four language tasks designed to span the progression of language development: two of which tap skills acquired during the preschool years and two of which tap skills that continue to develop into the school years. Normative language maps for each of these skill domains will be constructed from composite fMRI data from 10 boys and 10 girls at each year of age from 5 through 18 (N=280 normal subjects). Variations in these maps will be considered relative to both subject age and level of language skill (as measured by standardized testing). Finally, the utility of the normal language data will be evaluated by comparing it against data obtained from a group of 20 patients with impaired language ability resulting from perinatal stroke in the middle cerebral artery. This project will establish normative data for fMRI studies of language to be used as a reference in studies of a wide range of neurologic disorders in children.
Showing the most recent 10 out of 75 publications
