Myelination and organization of the frontal white matter in children: a diffusion tensor MRI study

MYELINATION is critical for the functional development of the brain, but th e time course of myelination during childhood is not well known. Diffusion tensor MR imaging (DTI) provides a new method for estimating myelination in vivo. Myelin restricts diffusion of water transverse to the axons, causing diffusion to be anisotropic. By quantifying the anisotropy, the progressiv e myelination of axons can be studied. Central white matter of the frontal lobe was studied in seven children (mean age 10 years) and five adults (mea n age 27 years). Anisotropy in the frontal white matter was significantly l ower in children than in adults, suggesting less myelination in children. M easurement of the coherence of white matter revealed that the right frontal lobe had a than the left more regular organization of axons frontal lobe, in both children and adults. The results demonstrate that maturation of the frontal white matter continues into the second decade of life. The time co urse of prefrontal maturation makes it possible that myelination is a basis for the gradual development of prefrontal functions, such as increased wor king memory capacity. (C) 1999 Lippincott Williams & Wilkins.