Longitudinal Mapping of Maturational Change in Brain Function-Structure Relations

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The overarching goal of the proposed studies is to longitudinally investigate the functional and behavioral significance of structural change in the form of gray matter thickness increases recently observed in classical brain language regions during the process of normal development. We will also assess functional activation in non-language frontal lobe regions (where cortical thinning has been observed) to evaluate the cognitive/functional significance and regional specificity of dynamic changes observed in our earlier studies of structural brain maturation. By delineating the relationship among language developments, executive function development, brain function, and brain structure, this study will bridge the informational gap on the neural basis of language and frontal function in the normally developing brain. We will use functional and structural magnetic resonance imaging and detailed neurocognitive assessments to assess the following specific aims: 1) To quantify change in functional and structural signal within children studied longitudinally; 2) To investigate whether change in functional signal across time is related to change in the underlying brain structure; and 3) To relate behavioral language and frontal lobe functioning change to changes in brain structure and function. We propose to study children between the ages of 5 and 9 years (with 2 years between repeat evaluations) when so many language and frontal lobe functions are rapidly changing as are brain structures related to these cognitive domains. The proposed longitudinal project will highlight how an integrated approach relating behavioral, functional, and structural data might yield important new insights on the complex nature of brain- behavior interactions. To our knowledge, this will be the first study to undertake such challenges by using both functional and structural MRI to examine, longitudinally, the neural networks associated with language processing (i.e., reading), within the same individuals, and to relate the normal developmental changes in the neural networks subserving language processing (as observed with fMRI) to age-related changes in brain morphometry (as assessed by structural MRI). Similar evaluations will be made with tests of frontal lobe functioning allowing assessment of relationships between patterns of change in language and non-language brain regions. The data gathered from the proposed longitudinal research program should enable us to more fully elucidate the neural developments associated with the emergence of mature linguistic and frontal lobe competence in normally developing children. Furthermore, these developmental findings will provide normative data for evaluating the patterns of brain dysfunction associated with the linguistic, communicative, and frontal lobe impairments observed in a variety of developmental disorders (e.g., dyslexia, autism, ADHD).