Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, California, USA.
SDSU/UC San Diego Joint Doctoral Program in Clinical Psychology, San Diego, California, USA.
Dev Neurobiol. 2022 Apr;82(3):261-274. doi: 10.1002/dneu.22874. Epub 2022 Apr 7.
Intracortical myelin is thought to play a significant role in the development of neural circuits and functional networks, with consistent evidence of atypical network connectivity in children with autism spectrum disorder (ASD). However, little is known about the development of intracortical myelin in the first years of life in ASD, during the critical neurodevelopmental period when autism symptoms first emerge. Using T1-weighted (T1w) and T2w structural magnetic resonance imaging (MRI) in 21 young children with ASD and 16 typically developing (TD) children, ages 1.5-5.5 years, we demonstrate the feasibility of estimating intracortical myelin in vivo using the T1w/T2w ratio as a proxy. The resultant T1w/T2w maps were largely comparable with those reported in prior T1w/T2w studies in TD children and adults, and revealed no group differences between TD children and those with ASD. However, differential associations between T1w/T2w and age were identified in several early myelinated regions (e.g., visual, posterior cingulate, precuneus cortices) in the ASD and TD groups, with age-related increase in estimated myelin content across the toddler and preschool years detected in TD children, but not in children with ASD. The atypical age-related effects in intracortical myelin, suggesting a disrupted myelination in the first years of life in ASD, may be related to the aberrant brain network connectivity reported in young children with ASD in some of the same cortical regions and circuits.
皮质内髓鞘被认为在神经回路和功能网络的发育中起着重要作用，自闭症谱系障碍（ASD）儿童的网络连接存在异常，这一证据确凿。然而，对于 ASD 儿童在生命的头几年皮质内髓鞘的发育知之甚少，而自闭症症状正是在这段关键的神经发育时期首次出现。我们使用 T1 加权（T1w）和 T2 加权（T2w）结构磁共振成像（MRI）对 21 名 ASD 儿童和 16 名典型发育（TD）儿童进行了研究，这些儿童年龄在 1.5 岁至 5.5 岁之间，证明了使用 T1w/T2w 比值作为替代物来估计体内皮质内髓鞘的可行性。所得的 T1w/T2w 图谱与 TD 儿童和成人的 T1w/T2w 研究中报道的图谱大致相当，且在 TD 儿童和 ASD 儿童之间没有发现组间差异。然而，在 ASD 和 TD 组的几个早期髓鞘化区域（例如，视觉、后扣带回、楔前叶皮质）中，T1w/T2w 与年龄之间的相关性存在差异，在 TD 儿童中，从幼儿期到学龄前，估计的髓鞘含量呈与年龄相关的增加，但在 ASD 儿童中没有发现。皮质内髓鞘的这种异常的与年龄相关的效应表明，在 ASD 儿童的生命的最初几年中髓鞘形成可能受到了破坏，这可能与在一些相同的皮质区域和回路中报告的 ASD 儿童的异常大脑网络连接有关。
