National Institutes of Health
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早發性精神分裂症（early onset schizophrenia）的少年的灰質會過渡消退；而孤獨症（autism）的兒童則出現異常的大腦由後向前的灰質增加。對皮層發育的研究能夠有助於更好地理解這些精神性疾病的發生。
Dynamic mapping of human cortical development during childhood through early adulthood
Communicated by Leslie G. Ungerleider, National Institutes of Health, Bethesda, MD, April 15, 2004 (received for review January 7, 2004)
Nitin Gogtay *, Jay N. Giedd *, Leslie Lusk *, Kiralee M. Hayashi , Deanna Greenstein *, A. Catherine Vaituzis *, Tom F. Nugent III *, David H. Herman *, Liv S. Clasen *, Arthur W. Toga , Judith L. Rapoport *, and Paul M. Thompson
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*Child Psychiatry Branch, National Institutes of Mental Health, National Institutes of Health, Bethesda, MD 20892; and Laboratory of Neuro Imaging, Department of Neurology, University of California School of Medicine, Los Angeles, CA 90095-1769
灰質是大腦和脊髓中神經細胞集中的部位，是調節機體機能的最高部位。很長時間都一直認為：在生命的最初的18個月，灰質呈爆發性地過度產生；隨後，沒有使用的神經回路會被拋棄而導緻灰質的穩定減少。直到上個世紀九十年代末，才有發現報道在青春期之前有第二波的灰質產生以及隨後的消退。
在新一期的《PNAS》上，科壆傢用核磁共振成像（magnetic resonance imaging ，MRI）的方法，對13名健康的兒童和少年進行了長達上十年的觀察，記錄到了不同腦中樞的成熟的先後。伴隨被觀測者的成長，他們每兩年就要進行一次大腦的核磁共振掃描。對4到21齡的健康大腦的發育過程的分析表明，大腦皮層的工作物質――灰質，在青少年時期，空間上大體呈現由後向前的消退。消退首噹其沖地發生於位於大腦後部和極前的控制感覺和運動功能的功能中心，其次是位於頂葉（parietal lobes）的和空間定位和語言相關的部位，最後是主理理解、推理和其他執行功過能前額皮層（prefrontal cortex）。控制基本功能的大腦中心成熟較早，而高級功能中心成熟較晚，和哺乳動物的大腦進化大體一緻。
peridot
We report the dynamic anatomical sequence of human cortical gray matter development between the age of 4-21 years using quantitative four-dimensional maps and time-lapse sequences. Thirteen healthy children for whom anatomic brain MRI scans were obtained every 2 years, for 8-10 years, were studied. By using models of the cortical surface and sulcal landmarks and a statistical model for gray matter density, human cortical development could be visualized across the age range in a spatiotemporally detailed time-lapse sequence. The resulting time-lapse "movies" reveal that (i) higher-order association cortices mature only after lower-order somatosensory and visual cortices, the functions of which they integrate, are developed, and (ii) phylogenetically older brain areas mature earlier than newer ones. Direct comparison with normal cortical development may help understanding of some neurodevelopmental disorders such as childhood-onset schizophrenia or autism.
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