Our goal is to generate an easily accessible MR database of quantitative normal brain development in a species of non-human primate closely related to the human. We plan to define age specific normal ranges of intersubject variability for each developmental measure for use in future studies of abnormal brain development patterned after human neuroanatomic and psychobehavioral disease. We will integrate quantitative imaging knowledge of normal brain development with biochemical, histologic and behavioral data available in the same animal.
Specific Aims : 1. Use a thin section. high resolution. coronal 3D volume SPGR sequence to noninvasively quantify structural changes in selected neural areas. Using computer assisted volumetric analysis and segmentation techniques we will measure the volume and visualize changes in brain shape which occur in specific cerebral structures of the developing vervet monky. 2. Use the information Inherent in the MR sequence above and from inversion recovery sequences to quantify regional myelinated white matter. Short TR, short TE sequences are sensitive to myelinated white matter and will be used in the same population using the same experimental design as in 1. above. 3. To validate specific aims 1. and 2. by performing a quantitative histologic study of age-matched cryomycrotomed vervet brain sections using a common anatomic coordinate system. The developing brain is composed of distinct processing regions, which mature in an organized sequential pattern. The pattern of growth and mvelination of major brain regions in the vervet monkey has not been described. Recently developed computer assisted segmentation protocols have improved quantitative structural analysis of both the human and primate brain. These approaches rely on intensity discrimination and edge detection The approaches assume a direct relationship between pixel intensity and physical substrate. A thin slice, short time to echo (TE), short time to repetition (TR), gradient recalled acquisition in the steady state (SPGR) sequence using a high field 3.OT magnet can provide a low noise, high resolution three dimensional data set for reconstruction of a variety of brain structures. This will allow longitudinal intra-subject evaluation of the rate and regional pattern of brain development as determined by volume changes in specific neural areas.
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