Herbert Martha R, Ziegler David A, Makris Nikos, Filipek Pauline A, Kemper Thomas L, Normandin Joseph J, Sanders Heather A, Kennedy David N, Caviness Verne S
Center for Morphometric Analysis, Massachusetts General Hospital, Harvard Medical School, Cambridge, MA, USA.
Ann Neurol. 2004 Apr;55(4):530-40. doi: 10.1002/ana.20032.
Increased brain volume in autism appears to be driven mainly by an unexplained white matter enlargement, and we have reported a similar phenomenon in developmental language disorder (DLD). Localization of this enlargement would strongly guide research into its cause, tissue basis, and functional implications. We utilized a white matter parcellation technique that divides cerebral white matter into an outer zone containing the radiate compartment and an inner zone containing sagittal and bridging system compartments. In both high-functioning autism and DLD, enlargement localized to the radiate white matter (all lobes in autism, all but parietal in DLD), whereas inner zone white matter compartments showed no volume differences from controls. Furthermore, in both autism and DLD, later or longer-myelinating regions showed greater volume increases over controls. Neither group showed cerebral cortex, corpus callosum, or internal capsule volume differences from control. Radiate white matter myelinates later than deep white matter; this pattern of enlargement thus is consistent with striking postnatal head circumference percentile increases reported in autism. These findings suggest an ongoing postnatal process in both autism and DLD that is probably intrinsic to white matter, that primarily affects intrahemispheric and corticocortical connections, and that places these two disorders on the same spectrum.
自闭症患者脑容量增加似乎主要是由不明原因的白质增大所致，我们在发育性语言障碍（DLD）中也报道过类似现象。这种增大的定位将有力地指导对其病因、组织基础及功能影响的研究。我们采用了一种白质分割技术，将脑白质分为包含放射状隔室的外侧区和包含矢状及桥接系统隔室的内侧区。在高功能自闭症和DLD中，增大均定位于放射状白质（自闭症累及所有脑叶，DLD除顶叶外累及所有脑叶），而内侧区白质隔室与对照组相比无体积差异。此外，在自闭症和DLD中，髓鞘形成较晚或髓鞘形成时间较长的区域与对照组相比体积增加更大。两组的大脑皮质、胼胝体或内囊体积与对照组相比均无差异。放射状白质的髓鞘形成比深部白质晚；因此，这种增大模式与自闭症患者出生后头围百分位数显著增加的情况一致。这些发现表明，自闭症和DLD在出生后都存在一个持续的过程，这可能是白质固有的，主要影响半球内和皮质间的连接，并将这两种疾病置于同一谱系中。
