小脑的认知功能一直以来都是认知神经科学领域的研究焦点。长久以来，小脑常常被简单理解为人的运动控制中枢，负责控制人体运动的平衡、协调和自动化。但是，近些年的研究发现，小脑虽然具有很小的体积，但是其皮层展开的表面积相当于大脑皮层的80%，其包含的神经元数量多于其他任何一个大脑核团。于是研究者开始关注小脑在高级认知功能中扮演的角色，例如工作记忆、认知控制和语言产生。这些研究都发现小脑（特别是小脑的后外侧）的功能不仅仅局限于运动控制。因此，越来越多的研究开始关心小脑在高级认知功能中的作用、小脑参与高级认知功能的神经活动模式、小脑-大脑网络连接模式及其神经优化。

双语者会说两种语言，在产生这两种语言时会面临冲突，因此需要调用其认知控制能力在使用目标语言说话时对另外一种非目标语言进行控制，这一过程被称为双语者的语言控制。语言控制是一个复杂高级认知功能，包含了对语言冲突的监控、对当前目标语言的维持和对非目标语言的抑制等过程。

因此，本研究以汉-英双语者的语言控制为研究对象，综合使用功能磁共振成像（fMRI）和经颅直流电刺激（tDCS）为研究手段，使用单变量分析、多变量分析、脑网络分析等数据分析方法，考察了小脑在双语者语言控制中的功能，进一步揭示了小脑在高级认知功能中的激活模式，小脑-大脑信息交互模式以及小脑面对物理刺激的神经优化。研究一招募了汉语-英语双语者，让他们完成基于图片命名的语言切换任务，并使用fMRI对其语言切换过程中的大脑活动进行扫描。研究使用基于SUIT的小脑单变量激活分析方法，对双语者的小脑在语言控制过程中的激活进行了分析。此外，在单变量激活分析的基础上，研究进一步使用扩展的统一结构方程模型（euSEM）进行建模，拟合出完整的双语者在语言控制过程中的小脑-大脑有效连接网络。研究也进一步使用标准曲线分析的方法揭示了双语者脑网络和行为表现之间的关系。研究二在研究一的基础上增加对被试小脑的经颅直流电刺激，并要求被试在刺激前后完成语言切换任务。结果发现，对被试的右侧小脑施加阳极直流电刺激可以显著提升其语言控制的表现，并且其行为表现的优化程度和其第二语言熟练度呈显著正相关。为了进一步区分小脑在双语者语言控制中的特异性激活模式，研究三招募了汉语-英语双语者，让他们分别完成语言切换任务（语言控制）和任务切换任务（认知控制），并使用fMRI扫描其脑活动。研究分别对上述两种任务进行单变量激活分析，同时使用基于支持向量机（SVM）的多变量分析方法区分小脑的多变量激活模式在两种任务下的差异。研究进一步揭示了小脑的功能分离及其和行为表现之间的关系。

这一系列研究结果表明：1）小脑（特别是小脑的后外侧皮层）参与了高级认知加工；2）小脑和大脑共同组成小脑-大脑网络，通过小脑内部连接、大脑内部连接和小脑-大脑连接进行信息传递共同支持双语者语言控制过程；3）神经调控手段揭示了双侧小脑的功能分离及其在语言控制中的作用；4）小脑的多变量激活模式进一步揭示了其在语言控制中的特异性激活模式。本研究首次详细揭示了小脑在双语者语言控制中的作用，为揭示语言控制的脑机制和小脑在高级认知功能中的作用都提供了全面而有力的证据。

The cognitive function of the human cerebellum could be characterized as enigmatic and remain a research focus in the field of cognitive neuroscience. The cerebellum is historically considered as an ad hoc neural apparatus for motion control that manages the coordination, stabilization, and automatism of motion in the human neural system. However, researchers have identified that the cerebellum has almost eighty percent of the surface area of the neocortex and has more neurons than any other part of the brain. Therefore, in recent years, researchers have attempted to detail the comprehensive role of the cerebellum in several cognitive processes, such as working memory, cognitive control, and verbal production. These studies have demonstrated that the cerebellum (especially the posterior lateral cerebellum) does not limit its role in motor control but plays a wide role in a number of cognitive functions. Hence, there is an increasing number of research focusing on the cerebellum's role in higher cognitive functions, the cerebellar activation patterns in these cognitive processes, the significance of the cerebro-cerebellar network, and the neuroplasticity of the cerebellum.

Bilinguals can speak two languages, which can trigger potential conflict when producing the target language; therefore, language control is engaged to control the non-target language. Language control is a comprehensive cognitive process containing the monitory of language conflict, attentional maintaining of the target language, and the inhibition of the non-target language. Hence, language control requires bilinguals' continuous ability of language production and cognitive control.

Using functional magnetic resonance imaging (fMRI) and transcranial direct current stimulation (tDCS), together with univariate analysis, brain network analysis, and the multivariate analysis, we revealed different functions of bilateral cerebellar lobules in bilingual language control, the functional significance of the cerebro-cerebellar network, and the neuroplasticity of the cerebellum. Specifically, in Study 1, Chinese-English bilinguals were required to perform a language switching task while their brain activity was scanned by fMRI. Brain univariate analysis showed that the bilateral posterolateral cerebellum was associated with bilingual language control and an effective connectivity analysis-built brain networks for the interaction between the cerebellum and the cerebral cortex. The specification curve analysis addressed a clear relationship between the brain network and bilinguals' behavioral performance. Furthermore, in Study 2, Chinese-English bilinguals received anodal tDCS over their left and the right posterolateral cerebellum while they were asked to perform the language switching task before and after the brain stimulation. Results demonstrated that the anodal tDCS over the right cerebellum significantly optimizes language control performance in bilinguals. Finally, in Study 3, Chinese-English bilinguals were recruited to perform the language switching task and the task switching task while the fMRI scanned their brain activity. We measured the task discriminate brain activity using univariate and multivariate pattern analyses. Together, these results reveal a precise asymmetrical functional distribution of the cerebellum in bilingual language production, suggesting that the right cerebellum is more involved in language control. In contrast, its left counterpart undertakes a computational role in cognitive control function by connecting with more prefrontal, parietal, subcortical brain areas.