Age of acquisition and proficiency have been identified as possible determinants in the neural localization of second language representation and in the nature of control mechanisms. However, the relationship is not yet clear between age of acquisition and proficiency on the one hand, and language switching and executive functions on the other. In the present study, we used anatomical and functional Magnetic Resonance (MR) Imaging to investigate the impact of age of acquisition. Two groups of highly proficient early and late bilinguals, carefully matched in other measures of proficiency, performed an overt picture-naming task in blocked and switched conditions.

We found that switching between languages in highly proficient bilinguals involves an increase of activity in areas reported as components associated with domain-general inhibitory processes. There was no effect of task language, only of whether the task involved language switching. Comparing the two groups indicated that highly proficient bilinguals use the same neural network for language production and control regardless of age of acquisition. Structural differences were apparent between the two groups in regions associated with language control.

We propose that language switching recruits a neural network that is engaged for domain-general executive control functions and that proficiency rather than age of acquisition exerts influence on language representations.

习得年龄和熟练程度已被确定为第二语言表示的神经定位和控制机制性质的可能决定因素。但是，一方面获取年龄和熟练程度，另一方面与语言切换和执行功能之间的关系尚不清楚。在本研究中，我们使用解剖学和功能性磁共振（MR）成像技术来研究采集年龄的影响。两组精通的早期和晚期双语者，在其他熟练程度方面均经过仔细匹配，在封闭和切换的情况下执行了明显的图片命名任务。

我们发现，在精通双语的语言之间进行切换会导致与域通用抑制过程相关的组件活动增加。任务语言没有影响，只有任务是否涉及语言切换没有影响。两组的比较表明，熟练的双语者使用相同的神经网络进行语言的产生和控制，而不管其习得年龄如何。两组之间在与语言控制相关的区域中存在明显的结构差异。

我们建议，语言切换应募集一个神经网络，该神经网络参与领域通用的执行控制功能，并且熟练程度而非习得年龄会对语言表示产生影响。