Executive Control in the Bilingual Brain

描述(申请人提供)：双语者有很强的语言控制能力。他们似乎能够在交谈中毫不费力地在语言之间切换，但很少用意想不到的语言创造单词。双语研究中越来越多的共识是，执行控制是语言控制的基础，这一假设导致了在涉及执行控制的非语言任务中发现双语优势。此外，功能磁共振成像研究报告说，在任务和语言转换过程中，类似的大脑区域也会活跃。尽管这一证据令人信服，但任务控制和语言控制之间的细微差别可能会被忽视。我们提出了一种强有力的方法来检验这一假设，即双语者依赖一般执行控制来实现语言控制，通过直接比较同一组个体的语言转换和任务转换来实现语言控制。这项研究的目标1将调查与任务和语言转换相关的年龄效应。老年人似乎在执行功能和语言控制方面表现出与年龄相关的显著变化。如果任务转换和语言转换是相似的过程，那么在这两个任务中的每一个任务上的表现都会相关，这样，保留了执行功能能力的老年人也会保留语言控制能力。这项拟议研究的目标2增加了一个神经成像部分，研究同一组人的语言转换和任务转换。这样的比较可以很好地控制每项任务所涉及的地区的调查。在双语者中，任务转换和语言转换之间的相似激活模式将暗示语言控制和执行控制的相似机制。或者，双语者的语言转换和任务转换的分离模式暗示了语言控制的额外机制，而执行控制并没有完全解释这一机制。在这两个实验中，一组匹配的单语对照将为识别双语者特有的处理机制提供进一步的杠杆作用。这项拟议的研究将详细阐述双语语言控制、执行控制及其在语言处理、老化的语言系统中的作用，并将为申请者提供在双语和老龄化领域取得成功所需的技能。

DESCRIPTION (provided by applicant): Bilinguals have powerful language control. They seem able to effortlessly switch between languages during conversation, but seldom produce words in an unintended language. A growing consensus in research on bilingualism is that executive control is the basis for language control, a hypothesis which led to the discovery of bilingual advantages in non-linguistic tasks involving executive control. Additionally, fMRI studies report similar brain regions active during task and language switching. Although this evidence is compelling, subtle differences between task and language control may be overlooked. We propose a powerful way to test the hypothesis that bilinguals rely on general executive control to achieve language control, by comparing language switching and task switching directly in the same group of individuals. Aim 1 of the proposed study will investigate age effects associated with task and language switching. Older adults appear to exhibit marked age-related shifts in executive function and language control. If task-switching and language-switching are analogous processes, performance on each of the two tasks will be related such that older adults who have preserved executive functioning abilities will have preserved language control abilities. Aim 2 of the proposed study adds a neuroimaging component that investigates language switching and task switching in the same group of individuals. Such a comparison allows for a well-controlled investigation of the regions involved in each task. Similar patterns of activation between task switching and language switching in bilinguals will suggest similar mechanisms underlying language control and executive control. Alternatively, dissociable patterns in language switching and task switching in bilinguals suggest additional mechanisms underlying language control not fully explained by executive control. In both experiments a group of matched monolingual controls will provide further leverage for identifying processing mechanisms unique to bilinguals. The proposed study will elaborate models of bilingual language control, executive control and its role in language processing, the aging language system, and will provide the applicant with skills necessary for leading a successful career in the field of bilingualism and aging.