Department of Radiology, University of Calgary, Calgary, AB, Canada.
Owerko Centre, Alberta Children Hospital Research Institute, University of Calgary, Calgary, AB, Canada.
Dev Sci. 2022 Mar;25(2):e13160. doi: 10.1111/desc.13160. Epub 2021 Jul 26.
Reading disorders are common in children and can impact academic success, mental health, and career prospects. Reading is supported by network of interconnected left hemisphere brain regions, including temporo-parietal, occipito-temporal, and inferior-frontal circuits. Poor readers often show hypoactivation and reduced gray matter volumes in this reading network, with hyperactivation and increased volumes in the posterior right hemisphere. We assessed gray matter development longitudinally in pre-reading children aged 2-5 years using magnetic resonance imaging (MRI) (N = 32, 110 MRI scans; mean age: 4.40 ± 0.77 years), half of whom had a family history of reading disorder. The family history group showed slower proportional growth (relative to total brain volume) in the left supramarginal and inferior frontal gyri, and faster proportional growth in the right angular, right fusiform, and bilateral lingual gyri. This suggests delayed development of left hemisphere reading areas in children with a family history of dyslexia, along with faster growth in right homologues. This alternate development pattern may predispose the brain to later reading difficulties and may later manifest as the commonly noted compensatory mechanisms. The results of this study further shows our understanding of structural brain alterations that may form the neurological basis of reading difficulties.
阅读障碍在儿童中很常见，会影响学业成功、心理健康和职业前景。阅读依赖于相互连接的左半球脑区网络，包括颞顶叶、枕颞叶和下额前回回路。阅读障碍患者的阅读网络常表现为低激活和灰质体积减少，而右后半球表现为过度激活和体积增加。我们使用磁共振成像（MRI）对 2-5 岁的阅读前儿童进行了纵向灰质发育评估（N=32，110 次 MRI 扫描；平均年龄：4.40±0.77 岁），其中一半有阅读障碍家族史。家族史组左侧缘上回和额下回的比例增长（相对于总脑容量）较慢，而右侧角回、右侧梭状回和双侧舌回的比例增长较快。这表明有阅读障碍家族史的儿童左半球阅读区发育延迟，而右侧同型区发育较快。这种替代的发育模式可能使大脑容易出现阅读困难，并且可能以后表现为常见的代偿机制。本研究的结果进一步表明，我们对可能构成阅读困难神经基础的结构脑改变的理解。
