Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, On, Canada.
Neurophysiol Clin. 2012 Jan-Feb;42(1-2):19-25. doi: 10.1016/j.neucli.2011.08.002. Epub 2011 Sep 1.
The tremendous changes in brain structure over childhood are critical to the development of cognitive functions. Neuroimaging provides a means of linking these brain-behaviour relations, as task protocols can be adapted for use with young children to assess the development of cognitive functions in both typical and atypical populations. This paper reviews some of our research using magnetoencephalography (MEG) and functional MRI (fMRI) in the study of cognitive development, with a focus on frontal lobe functions. Working memory for complex abstract patterns showed clear development in terms of the recruitment of frontal regions, seen with fMRI, with indications of strategy differences across the age range, from 6 to 35 years of age. Right hippocampal involvement was also evident in these n-back tasks, demonstrating its involvement in recognition in simple working memory protocols. Children born very preterm (7 to 9 years of age) showed reduced fMRI activation particularly in the precuneus and right hippocampal regions relative to control children. In a large normative n-back study (n=90) with upright and inverted faces, MEG data also showed right hippocampal activation that was present across the age range; frontal sources were evident only from 10 years of age. Other studies have investigated the development of set shifting, an executive function that is often deficit in atypical populations. fMRI showed recruitment of frontal areas, including the insula, that have significantly different patterns in children (7 to 14 years of age) with autism spectrum disorder compared to typically developing children, indicating that successful performance implicated differing strategies in these two groups of children. These types of studies will help our understanding of both normal brain-behaviour development and cognitive dysfunction in atypically developing populations.
儿童期大脑结构的巨大变化对认知功能的发展至关重要。神经影像学提供了一种将这些大脑-行为关系联系起来的方法，因为任务方案可以适应儿童使用，以评估典型和非典型人群中认知功能的发展。本文综述了我们使用脑磁图（MEG）和功能磁共振成像（fMRI）研究认知发展的部分研究，重点是额叶功能。使用 fMRI 研究表明，对于复杂抽象模式的工作记忆在招募额叶区域方面有明显的发展，并且在 6 至 35 岁的年龄范围内存在策略差异的迹象。在这些 n 回任务中，右侧海马也明显参与，表明其在简单工作记忆协议中的识别作用。极早产（7 至 9 岁）的儿童与对照组儿童相比，fMRI 激活明显减少，尤其是在楔前叶和右侧海马区域。在一项大型正常 n 回测试（n=90）中，包括直立和倒置的面部，MEG 数据还显示出右侧海马的激活，该激活存在于整个年龄范围内；只有从 10 岁开始才出现额叶源。其他研究还调查了执行功能的转变发展，这种执行功能在非典型人群中通常存在缺陷。fMRI 显示额叶区域的招募，包括脑岛，在自闭症谱系障碍儿童（7 至 14 岁）中与正常发育儿童相比，其模式有明显差异，表明这两组儿童的成功表现涉及不同的策略。这些类型的研究将有助于我们理解正常大脑-行为发展和非典型发育人群的认知功能障碍。
