Conturo Thomas E, Williams Diane L, Smith Charles D, Gultepe Eren, Akbudak Erbil, Minshew Nancy J
Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Int Neuropsychol Soc. 2008 Nov;14(6):933-46. doi: 10.1017/S1355617708081381.
MRI diffusion-tensor tracking (DTT) was performed in 17 high-functioning adolescents/adults with autism and 17 pairwise-matched controls. White matter pathways involved in face processing were examined due to the relevance of face perception to the social symptoms of autism, and due to known behavioral and functional imaging findings in autism. The hippocampo-fusiform (HF) and amygdalo-fusiform (AF) pathways had normal size and shape but abnormal microstructure in the autism group. The right HF had reduced across-fiber diffusivity (D-min) compared with controls, opposite to the whole-brain effect of increased D-min. In contrast, left HF, right AF, and left AF had increased D-min and increased along-fiber diffusivity (D-max), more consistent with the whole-brain effect. There was a general loss of lateralization compared with controls. The right HF D-min was markedly low in the autism subgroup with lower Benton face recognition scores, compared with the lower-Benton control subgroup, and compared with the higher-Benton autism subgroup. Similar behavioral relationships were found for performance IQ. Such results suggest an early functionally-significant pathological process in right HF consistent with small-diameter axons (with correspondingly slower neural transmission) and/or higher packing density. In left AF and HF, changes were interpreted as secondary, possibly reflecting axonal loss and/or decreased myelination.
对17名高功能自闭症青少年/成人及17名配对对照者进行了磁共振成像扩散张量追踪（DTT）。由于面部感知与自闭症社交症状相关，且自闭症患者有已知的行为和功能成像结果，因此研究了参与面部处理的白质通路。自闭症组的海马 - 梭状回（HF）和杏仁核 - 梭状回（AF）通路大小和形状正常，但微观结构异常。与对照组相比，右侧HF的跨纤维扩散率（D-min）降低，与全脑D-min增加的效应相反。相比之下，左侧HF、右侧AF和左侧AF的D-min增加，沿纤维扩散率（D-max）增加，更符合全脑效应。与对照组相比，整体的偏侧化有所丧失。与低本顿对照组亚组以及高本顿自闭症亚组相比，在本顿面部识别分数较低的自闭症亚组中，右侧HF的D-min明显较低。在操作智商方面也发现了类似的行为关系。这些结果表明，右侧HF存在早期功能上显著的病理过程，这与小直径轴突（相应地神经传导较慢）和/或较高的堆积密度一致。在左侧AF和HF中，变化被解释为继发性的，可能反映了轴突损失和/或髓鞘形成减少。
