Carper Ruth A, Moses Pamela, Tigue Zachary D, Courchesne Eric
Laboratory for Research on the Neuroscience of Autism, Children's Hospital Research Center, San Diego, California, USA.
Neuroimage. 2002 Aug;16(4):1038-51. doi: 10.1006/nimg.2002.1099.
Metabolic, functional, behavioral, and histologic studies suggest that the structure of the cerebrum may be abnormal in autism. In a previous cross-sectional study we found abnormal enlargement of cerebral cortex and cerebral white matter volumes in autistic 2- and 3-year-olds and abnormally slow rates of volume change across later ages. In the present study, we assessed whether these volume abnormalities are limited to particular cerebral regions or are pervasive throughout the cerebrum. We used magnetic resonance imaging (MRI) to quantify volumes of cerebral lobes (frontal, temporal, parietal, and occipital regions), using classic sulcal boundaries to define regions. We examined 38 boys with autism and 39 normal control boys between the ages of 2 and 11 years. Several regions showed signs of gray matter and white matter hyperplasia in 2- and 3-year-old patients (as much as 20% enlargement), but there appeared to be an anterior to posterior gradient in the degree of hyperplasia. The frontal lobe showed the greatest enlargement while the occipital lobe was not significantly different from normal. Gray and white matter differences were not found in the older children. By examining the relationships between regional volumes and subject age, we found that frontal, temporal, and parietal white matter volumes, as well as frontal and temporal gray matter volumes, changed at significantly slower rates in autism patients than in controls across the 2- to 11-year-age range. For example, frontal lobe white matter volume increased by about 45% from 2-4 years of age to 9-11.5 years, but by only 13% in autistic patients. Mechanisms that might account for early hyperplasia are discussed as they might relate to the regional differences in degree of abnormality. For instance, possible influences of neurotrophic factors, or of abnormal afferent activity from other affected brain regions are considered.
代谢、功能、行为和组织学研究表明，自闭症患者大脑的结构可能存在异常。在之前的一项横断面研究中，我们发现2岁和3岁自闭症儿童的大脑皮层和脑白质体积异常增大，且在之后的年龄段体积变化率异常缓慢。在本研究中，我们评估了这些体积异常是局限于特定脑区还是遍布整个大脑。我们使用磁共振成像（MRI）来量化脑叶（额叶、颞叶、顶叶和枕叶区域）的体积，利用经典的脑沟边界来定义区域。我们检查了38名2至11岁的自闭症男孩和39名正常对照男孩。在2岁和3岁的患者中，几个区域出现了灰质和白质增生的迹象（增大多达20%），但增生程度似乎存在从前到后的梯度。额叶增大最为明显，而枕叶与正常情况无显著差异。年龄较大的儿童未发现灰质和白质差异。通过检查区域体积与受试者年龄之间的关系，我们发现，在2至11岁的年龄范围内，自闭症患者额叶、颞叶和顶叶的白质体积以及额叶和颞叶的灰质体积变化速度明显慢于对照组。例如，额叶白质体积从2至4岁到9至11.5岁增加了约45%，而自闭症患者仅增加了13%。文中讨论了可能导致早期增生的机制，因为它们可能与异常程度的区域差异有关。例如，考虑了神经营养因子或其他受影响脑区异常传入活动的可能影响。
