Bilingualism is a natural laboratory for studying whether the brain’s structural connectome is influenced by different aspects of language experience. However, evidence on how distinct components of bilingual experience may contribute to structural brain adaptations is mixed. The lack of consistency, however, may depend, at least in part, on methodological choices in data acquisition and processing. Herein, we adopted the Network Neuroscience framework to investigate how individual differences in second language (L2) exposure, proficiency, and age of acquisition (AoA) – measured as continuous between-subject variables – relate to whole-brain structural organization. We observed that L2 exposure modulated the connectivity of two networks of regions subserving language comprehension and production. L2 proficiency was associated with enhanced connectivity within a rostro-caudal network, which supports language selection and word learning. Moreover, L2 AoA and exposure affected inter-hemispheric communication between control-related regions. These findings expand mechanistic knowledge about particular environmental factors associated with specific variation in brain structure.

双语是研究大脑结构连接组是否受语言经验不同方面影响的天然实验室。然而，关于双语体验的不同组成部分如何促进结构性大脑适应的证据是混合的。然而，缺乏一致性可能至少部分取决于数据采集和处理中的方法选择。在此，我们采用网络神经科学框架来研究第二语言 (L2) 暴露、熟练程度和习得年龄 (AoA) 的个体差异（以连续的受试者间变量衡量）与全脑结构组织的关系。我们观察到 L2 暴露调节了两个区域网络的连通性，这些网络支持语言理解和生产。L2 熟练程度与支持语言选择和单词学习的 rostro-caudal 网络内的增强连接有关。此外，L2 AoA 和暴露影响了控制相关区域之间的半球间通信。这些发现扩展了与大脑结构特定变化相关的特定环境因素的机械知识。