Klein Denise, Mok Kelvin, Chen Jen-Kai, Watkins Kate E
Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, H3A 2B4, Canada.
Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, H3A 2B4, Canada.
Brain Lang. 2014 Apr;131:20-4. doi: 10.1016/j.bandl.2013.05.014. Epub 2013 Jun 29.
We examined the effects of learning a second language (L2) on brain structure. Cortical thickness was measured in the MRI datasets of 22 monolinguals and 66 bilinguals. Some bilingual subjects had learned both languages simultaneously (0-3 years) while some had learned their L2 after achieving proficiency in their first language during either early (4-7 years) or late childhood (8-13 years). Later acquisition of L2 was associated with significantly thicker cortex in the left inferior frontal gyrus (IFG) and thinner cortex in the right IFG. These effects were seen in the group comparisons of monolinguals, simultaneous bilinguals and early and late bilinguals. Within the bilingual group, significant correlations between age of acquisition of L2 and cortical thickness were seen in the same regions: cortical thickness correlated with age of acquisition positively in the left IFG and negatively in the right IFG. Interestingly, the monolinguals and simultaneous bilinguals did not differ in cortical thickness in any region. Our results show that learning a second language after gaining proficiency in the first language modifies brain structure in an age-dependent manner whereas simultaneous acquisition of two languages has no additional effect on brain development.
我们研究了学习第二语言（L2）对大脑结构的影响。在22名单语者和66名双语者的磁共振成像（MRI）数据集中测量了皮质厚度。一些双语受试者同时学习了两种语言（0至3岁），而一些人则在幼儿期（4至7岁）或童年后期（8至13岁）在熟练掌握第一语言后学习了他们的第二语言。后期学习第二语言与左侧额下回（IFG）皮质显著增厚和右侧IFG皮质变薄有关。这些效应在单语者、同时双语者以及早期和晚期双语者的组间比较中均可见。在双语组中，在相同区域观察到第二语言习得年龄与皮质厚度之间存在显著相关性：左侧IFG皮质厚度与习得年龄呈正相关，而右侧IFG则呈负相关。有趣的是，单语者和同时双语者在任何区域的皮质厚度均无差异。我们的结果表明，在熟练掌握第一语言后学习第二语言会以年龄依赖的方式改变大脑结构，而同时习得两种语言对大脑发育没有额外影响。
