Li Le, Emmorey Karen, Feng Xiaoxia, Lu Chunming, Ding Guosheng
State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University Beijing, China.
Laboratory for Language and Cognitive Neuroscience, School of Speech, Language, and Hearing Sciences, San Diego State University San Diego, CA, USA.
Front Hum Neurosci. 2016 Nov 30;10:616. doi: 10.3389/fnhum.2016.00616. eCollection 2016.
Bilingual studies have revealed critical roles for the dorsal anterior cingulate cortex (dACC) and the left caudate nucleus (Lcaudate) in controlling language processing, but how these regions manage activation of a bilingual's two languages remains an open question. We addressed this question by identifying the functional connectivity (FC) of these control regions during a picture-naming task by bimodal bilinguals who were fluent in both a spoken and a signed language. To quantify language control processes, we measured the FC of the dACC and Lcaudate with a region specific to each language modality: left superior temporal gyrus (LSTG) for speech and left pre/postcentral gyrus (LPCG) for sign. Picture-naming occurred in either a single- or dual-language context. The results showed that in a single-language context, the dACC exhibited increased FC with the target language region, but not with the non-target language region. During the dual-language context when both languages were alternately the target language, the dACC showed strong FC to the LPCG, the region specific to the less proficient (signed) language. By contrast, the Lcaudate revealed a strong connectivity to the LPCG in the single-language context and to the LSTG (the region specific to spoken language) in the dual-language context. Our findings suggest that the dACC monitors and supports the processing of the target language, and that the Lcaudate controls the selection of the less accessible language. The results support the hypothesis that language control processes adapt to task demands that vary due to different interactional contexts.
双语研究揭示了背侧前扣带回皮质（dACC）和左侧尾状核（Lcaudate）在控制语言处理方面的关键作用，但这些区域如何管理双语者两种语言的激活仍是一个悬而未决的问题。我们通过识别在图片命名任务中，那些同时精通口语和手语的双模式双语者的这些控制区域的功能连接性（FC），来解决这个问题。为了量化语言控制过程，我们测量了dACC和Lcaudate与每种语言模态特有的一个区域之间的FC：用于语音的左侧颞上回（LSTG）和用于手语的左侧中央前/后回（LPCG）。图片命名发生在单语或双语环境中。结果表明，在单语环境中，dACC与目标语言区域的FC增加，但与非目标语言区域的FC没有增加。在双语环境中，当两种语言交替成为目标语言时，dACC显示出与LPCG（不太熟练的（手语）语言特有的区域）有很强的FC。相比之下，Lcaudate在单语环境中与LPCG有很强的连接，在双语环境中与LSTG（口语特有的区域）有很强的连接。我们的研究结果表明，dACC监测并支持目标语言的处理，而Lcaudate控制较难获取语言的选择。这些结果支持了这样一种假设，即语言控制过程会适应因不同互动环境而变化的任务需求。
