Laboratory of Brain Imaging, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland; Laboratory of Language Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.
Basque Center of Cognition, Brain and Language, Donostia-San Sebstián, Spain; Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
Neuropsychologia. 2024 Nov 5;204:108973. doi: 10.1016/j.neuropsychologia.2024.108973. Epub 2024 Aug 14.
The goal of this study was to investigate the impact of the age of acquisition (AoA) on functional brain representations of sign language in two exceptional groups of hearing bimodal bilinguals: native signers (simultaneous bilinguals since early childhood) and late signers (proficient sequential bilinguals, who learnt a sign language after puberty). We asked whether effects of AoA would be present across languages - signed and audiovisual spoken - and thus observed only in late signers as they acquired each language at different life stages, and whether effects of AoA would be present during sign language processing across groups. Moreover, we aimed to carefully control participants' level of sign language proficiency by implementing a battery of language tests developed for the purpose of the project, which confirmed that participants had high competences of sign language. Between-group analyses revealed a hypothesized modulatory effect of AoA in the right inferior parietal lobule (IPL) in native signers, compared to late signers. With respect to within-group differences across languages we observed greater involvement of the left IPL in response to sign language in comparison to spoken language in both native and late signers, indicating language modality effects. Overall, our results suggest that the neural underpinnings of language are molded by the linguistic characteristics of the language as well as by when in life the language is learnt.
本研究旨在探究获得年龄（AoA）对两种特殊的听觉双语者（即：母语为手语的手语使用者和后天习得手语的熟练顺序双语者）的手语功能脑区的影响。我们询问 AoA 的影响是否会在语言之间（手语和视听口语）存在，并且仅在后天习得手语的双语者中观察到，因为他们在不同的人生阶段学习了每种语言，以及 AoA 的影响是否会在手语处理过程中存在于不同群体之间。此外，我们旨在通过实施一套为该项目专门开发的语言测试来仔细控制参与者的手语熟练程度，这证实了参与者具有较高的手语能力。组间分析显示，母语为手语的手语使用者的右侧下顶叶（IPL）中存在 AoA 的假设调节效应，而与后天习得手语的手语使用者相比。关于语言之间的组内差异，我们观察到母语为手语的手语使用者和后天习得手语的手语使用者在左 IPL 中对手语的反应比对口语的反应更大，这表明了语言模态的影响。总的来说，我们的结果表明，语言的神经基础是由语言的语言特征以及语言学习的人生阶段塑造的。
