Center for the Study of Learning, Department of Pediatrics, Georgetown University Medical Center, Washington, District of Columbia, USA.
Interdisciplinary Program in Neuroscience, Georgetown University, Washington, District of Columbia, USA.
Hum Brain Mapp. 2022 Nov;43(16):4817-4834. doi: 10.1002/hbm.26008. Epub 2022 Jul 18.
Gray matter has been shown to be greater in early bilingual adults relative to monolingual adults in regions associated with language (Mechelli et al., 2004), and executive control (EC; Olulade et al., 2016). It is not known, however, if language experience-dependent differences in gray matter volume (GMV) exist in children. Further, any such differences are likely not to be the same as those observed in early bilingual adults, as children have had relatively shorter duration of dual-language exposure and/or less development of brain regions serving EC. We tested these predictions by comparing GMV in Spanish-English early bilingual and English monolingual children, and Spanish-English early bilingual and English monolingual adults (n = 122). Comparing only children revealed relatively more GMV in the bilinguals in bilateral frontal, right inferior frontal, and right superior parietal cortices (regions associated with EC). Bilinguals, however, had less GMV in left inferior parietal cortex (region associated with language). An ANOVA including these children with bilingual and monolingual adults revealed interactions of Language Background by Age Group. There were no regions of more GMV in bilinguals relative to monolinguals that were less pronounced in children than adults, despite the children's shorter dual-language experience. There were relative differences between bilingual and monolingual children that were more pronounced than those in adults in left precentral gyrus and right superior parietal lobule (close to, but not directly in areas associated with EC). Together, early bilingual children manifest relative differences in GMV, and, surprisingly, these do not diverge much from those observed in studies of bilingual adults.
灰质已被证明在与语言（Mechelli 等人，2004 年）和执行控制（EC；Olulade 等人，2016 年）相关的区域中，早期双语成年人比单语成年人更多。然而，目前尚不清楚儿童是否存在与语言经验相关的灰质体积（GMV）差异。此外，任何此类差异都不太可能与早期双语成年人观察到的差异相同，因为儿童接触双语的时间相对较短，并且大脑中负责 EC 的区域发育程度较低。我们通过比较西班牙语-英语早期双语和英语单语儿童以及西班牙语-英语早期双语和英语单语成年人（n=122）的 GMV 来检验这些预测。仅比较儿童发现双语者双侧额前皮质、右额下回和右顶上叶皮质（与 EC 相关的区域）的 GMV 相对较多。然而，双语者左顶下小叶皮质（与语言相关的区域）的 GMV 较少。包括这些双语和单语成年人在内的 ANOVA 显示了语言背景与年龄组的相互作用。在双语者相对于单语者的 GMV 中，没有发现更多的区域，这些区域在儿童中不如在成人中明显，尽管儿童的双语经验较短。双语儿童和单语儿童之间存在相对差异，这些差异在左中央前回和右顶上小叶（接近，但不在 EC 相关区域）比成人更明显。总之，早期双语儿童表现出 GMV 的相对差异，令人惊讶的是，这些差异与双语成年人研究中观察到的差异没有太大区别。
