Bilinguals have a remarkable ability to juggle two languages. A central question in the field is concerned with the control mechanisms that enable bilinguals to switch language with ease. Theoretical models and neuroimaging evidence suggest that a range of control processes are at play during language switching, and their underlying neural mechanisms are closely related to executive function. What remains unclear is when these control processes are engaged in language switching. In this study, we used magnetoencephalography (MEG) to examine the brain activity while unbalanced Mandarin-English bilinguals performed a digit-naming task with cued language switching. Following presentation of the language cue, an asymmetrical switch effect was observed in the left inferior frontal gyrus (IFG), where switch-related increase in evoked brain activity was larger for switching into the non-dominant language. Following presentation of the naming target, evoked brain activity in the right IFG was larger when naming was required in the non-dominant language compared to the dominant language. We conclude that control processes take place in two stages during language switching, with the left IFG resolving interference following cue presentation and the right IFG inhibiting competing labels following target presentation.

双语者具有处理两种语言的非凡能力。该领域的中心问题与使双语者能够轻松切换语言的控制机制有关。理论模型和神经影像学证据表明，在语言切换过程中，一系列控制过程在起作用，其潜在的神经机制与执行功能密切相关。尚不清楚的是何时这些控制过程涉及语言切换。在这项研究中，我们使用脑磁图（MEG）来检查大脑活动，而不平衡的普通话-英语双语者通过提示语言切换来执行数字命名任务。呈现语言提示后，在左下额回（IFG）中观察到不对称切换效果，其中与切换相关的诱发大脑活动的增加更大，从而切换为非主导语言。提出命名目标后，与非优势语言相比，以非优势语言进行命名时，右侧IFG中诱发的大脑活动较大。我们得出结论，在语言切换过程中，控制过程分两个阶段进行，