Interaction of language and control processes in monolingual and bilingual cognition

神经可塑性是指大脑结构和功能随着经验的变化而改变，为认知能力的终身适应提供了可能。这种适应可能是一种有效的干预方法，旨在保护衰老的认知功能。一种被证明可以改变认知功能的经历是双语：在一生中，双语者在执行控制（EC）的各种测试中表现优于单语者。然而，对于这些影响，特别是对双语者和更普遍的神经可塑性来说，还有很多未知之处。拟议的研究将使用行为和脑电图测量来研究单语或双语的年轻人和老年人，以了解这种经历如何影响认知能力。在这项研究中有两个关键的突出问题。***1：双语认知效果的条件***尽管大量研究报告了英语学习中显著的双语优势，但研究之间存在很大差异，有些研究没有发现群体差异。因此，一个重要的问题是确定观察双语效应的条件。总的来说，在儿童和老年人中比在年轻人中更容易发现群体差异，在复杂任务中比在简单任务中更容易发现群体差异，在神经成像研究中比在行为研究中更容易发现群体差异。这些和其他因素将被调查，以确定在何种条件下双语会导致这些有益的结果。***2：加工功能的改变***通常对双语者EC增强的解释是，双语者使用EC来控制对两种共同激活的语言的注意，从而选择目标语言，避免其他语言的入侵。双语者两种语言的联合激活是有案可查的，因此语言选择是双语语言使用中一个长期存在的问题。我们的想法是，使用欧共体网络进行语言选择，加强了该网络，并使其在其他目的上更有效。然而，也有可能是EC网络被修改，创造了一个双语者用于言语和非言语处理的网络，这个网络与单语者使用的网络有质的不同。双语创造了一个新的综合控制网络的可能性将有助于解释双语者比单语者更晚出现痴呆迹象的发现。由于痴呆症通常首先表现为记忆问题，因此很难理解双语EC优势如何保护表现。然而，一个完整的控制网络可以让双语者通过依赖更完整的控制网络来弥补某些领域的失败。因此，双语者使用的控制网络的性质的证据对理解神经可塑性的一个重要方面具有重要意义，这可能对保持衰老时的认知功能有一定的应用。* * * * * * * *

Neuroplasticity is the idea that brain structure and function change in response to experience, offering the possibility for lifelong adaptation of cognitive ability. Such adaptation may be a powerful approach to interventions designed to protect cognitive function with aging. One experience that has been shown to modify cognitive function is bilingualism: across the lifespan, bilinguals outperform monolinguals on various tests of executive control (EC). However, much is unknown about these effects, both for bilingualism in particular and neuroplasticity more generally. The proposed studies will use behavioural and EEG measures to study younger and older adults who are monolingual or bilingual to understand how this experience affects cognitive ability. There are two crucial outstanding issues in this research.***1: Conditions for cognitive effects of bilingualism***Although a large body of research has reported significant bilingual advantages in EC, there is great variability across studies with some finding no group differences. An important question, therefore, is to determine the conditions under which effects of bilingualism are observed. In general, group differences are more likely found with children and older adults than with younger adults, with complex tasks than with simpler tasks, and with neuroimaging studies than with behavioural studies. These and other factors will be investigated to determine conditions under which bilingualism leads to these beneficial outcomes. ***2: Functional changes in processing***The usual explanation for enhanced EC in bilinguals is that bilinguals use EC to control attention to two jointly activated languages so they can select the target language and avoid intrusions from the other language. The joint activation of both languages for bilinguals is well documented, so language selection is a constant problem of bilingual language use. The idea is that the use of the EC network for language selection fortifies that network and makes it more efficient for other purposes. However, it may also be that the EC network is modified to create a network that is used by bilinguals for both verbal and nonverbal processing, a network that is qualitatively different from that used by monolinguals. This possibility that bilingualism creates a new integrated control network would help to explain the finding that bilinguals show signs of dementia later than monolinguals. Because dementia is usually displayed first as a memory problem, it is hard to understand how bilingual EC advantages would protect performance. However, an integrated control network could allow bilinguals to compensate for failure in some domains by relying on more intact ones. Thus, evidence for the nature of the control networks used by bilinguals has implications for understanding an important aspect of neuroplasticity that may have some application to preserving cognitive function in aging. ********