Department of Psychology and Human Development, Vanderbilt University, Nashville, Tennessee, USA.
Institute for Learning & Brain Sciences, University of Washington, Seattle, Washington, USA.
Hum Brain Mapp. 2021 Aug 1;42(11):3534-3546. doi: 10.1002/hbm.25450. Epub 2021 May 5.
A previous functional magnetic resonance imaging (fMRI) study by Weiss et al. (Weiss et al., Human Brain Mapping, 2018, 39, 4334-4348) examined brain specialization for phonological and semantic processing of spoken words in young children who were 5 to 6 years old and found evidence for specialization in the temporal but not the frontal lobe. According to a prominent neurocognitive model of language development (Skeide & Friederici, Nature Reviews Neuroscience, 2016, 17, 323-332), the frontal lobe matures later than the temporal lobe. Thus, the current study aimed to examine if brain specialization in the frontal lobe can be observed in a slightly older cohort of children aged 7 to 8 years old using the same experimental and analytical approach as in Weiss et al. (Weiss et al., Human Brain Mapping, 2018, 39, 4334-4348). One hundred and ten typically developing children were recruited and were asked to perform a sound judgment task, tapping into phonological processing, and a meaning judgment task, tapping into semantic processing, while in the MRI scanner. Direct task comparisons showed that these children exhibited language specialization in both the temporal and the frontal lobes, with the left posterior dorsal inferior frontal gyrus (IFG) showing greater activation for the sound than the meaning judgment task, and the left anterior ventral IFG and the left posterior middle temporal gyrus (MTG) showing greater activation for the meaning than the sound judgment task. These findings demonstrate that 7- to 8-year-old children have already begun to develop a language-related specialization in the frontal lobe, suggesting that early elementary schoolers rely on both specialized linguistic manipulation and representation mechanisms to perform language tasks.
Weiss 等人的先前一项功能磁共振成像（fMRI）研究（Weiss 等人，《人类大脑图谱》，2018 年，39 卷，4334-4348）检查了 5 至 6 岁的幼儿在口语单词的语音和语义处理方面的大脑专业化，并发现了颞叶而非额叶专业化的证据。根据语言发展的一种著名神经认知模型（Skeide 和 Friederici，《自然评论神经科学》，2016 年，17 卷，323-332），额叶比颞叶成熟得晚。因此，本研究旨在使用与 Weiss 等人（Weiss 等人，《人类大脑图谱》，2018 年，39 卷，4334-4348）相同的实验和分析方法，检查在年龄稍大的 7 至 8 岁儿童群体中是否可以观察到额叶的大脑专业化。招募了 110 名典型发育儿童，并要求他们在 MRI 扫描仪中执行声音判断任务，该任务涉及语音处理，以及执行意义判断任务，该任务涉及语义处理。直接任务比较表明，这些儿童在颞叶和额叶都表现出语言专业化，左侧后背部下额回（IFG）对声音的激活大于对意义的激活，左侧前腹侧 IFG 和左侧后中部颞叶（MTG）对意义的激活大于对声音的激活。这些发现表明，7 至 8 岁的儿童已经开始在额叶发展出与语言相关的专业化，这表明小学生已经开始依赖于专门的语言处理和表示机制来执行语言任务。
