言语学习引起的脑功能和结构变化

文章系统介绍了言语学习引起的脑功能和结构可塑性变化研究的最新进展,例如：第二语言的词汇——语义学习引起的脑功能变化主要受熟练程度的影响,而句法学习引起的脑功能变化主要受获得年龄的影响;实验室言语训练可以引起语言加工相关区域激活增强或减弱,以及出现新的激活区域;第二语言学习导致了左侧顶下皮层灰质密度增加。此外,文章还总结了言语学习的脑成像研究中常用的实验范式,并提出了有待于进一步解决的关键问题     

脑可塑性研究综述

本文简要总结了脑可塑性实验研究的三个方面：(1)脑损伤的研究,(2)学习和训练的脑可塑研究,(3)双语习得的研究。目前研究脑可塑的一个重要方向是通过学习和训练,考察认知成分的获得与大脑皮层活动状态变化之间的关系。这些研究说明大脑的成熟是一个动态发展的过程,它的结构和功能在一定程度上具有可塑性。     

学习与脑可塑性的研究进展及其教育意义

脑可塑性是指脑在外界环境和经验的作用下不断塑造其结构和功能的能力.本文阐述了神经科学与认知神经科学关于学习影响动物脑与人脑结构与功能的研究进展.研究表明,学习与经验可以改变脑皮层的厚度与树突的结构,增加树突棘的数量,修饰其形状,对脑的功能代表区产生影响.学习与脑可塑性的多层面研究为理解学习的本质规律以及教育研究与实践提供重要的启示.     

双语经验对认知能力的影响

综合近年关于双语经验对认知影响的研究, 探讨双语经验对认知的积极和消极两方面的影响, 且着重介绍了双语经验对认知的积极影响。双语经验对认知的积极影响主要体现在语言认知能力、非语言认知能力和中央执行功能几个方面。此外, 进一步对双语促进认知发展的原因进行了两方面的分析：一个是双语思维经验促进抑制控制的发展, 另一个双语学习经验强化双语者的左右脑交流, 从而导致脑功能活动方式的变化。最后, 对今后双语与认知关系的研究中需要注意的问题提出了一些思考。     

双语控制的神经基础及其对第二语言教学的启示

双语加工和控制的认知神经科学研究发现,与一般性执行功能有关的最关键的脑区前额皮层,以及其它的相关脑区及神经基础如前扣带回、基底神经节和下顶叶等参与了双语语言理解和语言产生的双语控制中。这些研究成果对于利用第二语言促进认知控制能力的发展,以及利用认知控制训练促进高效率的第二语言教学有着重要的启示。     

老年人的脑可塑性:来自认知训练的证据

老年人大脑结构和功能衰退是其认知功能下降的重要原因。然而,老年人的大脑仍然保持了一定的可塑性。随着神经影像技术的发展,大量研究发现认知训练能够对老年人的大脑结构和功能产生积极影响:(1)在脑结构方面,表现为大脑皮层灰质体积增加、白质神经纤维连接增强;(2)在进行认知任务时,表现为脑功能网络发生重组;(3)在静息态脑功能方面,表现为脑自发活动功能性重组以及功能连接增强。未来的认知训练研究需要考察老年人大脑可塑性存在个体差异的多种影响因素,并通过纵向追踪研究来探讨大脑可塑性的保持性和迁移效应。     

聋人早期手语经验对脑功能及结构的塑造作用

语言经验对脑功能和结构发展有重要的塑造作用。然而, 目前的相关证据主要来自对脑损伤导致的失语症病人的语言康复、第二语言学习以及针对成人读者进行的语言训练等方面的研究。幼儿时期的早期语言经验对脑结构与功能发展的影响更加重要, 但直接的研究证据却相当缺乏。本文提出一个研究设想, 拟综合使用多种脑成像技术, 系统探讨有早期手语经验和无早期手语经验的聋人个体在脑皮层语言功能的组织及脑结构发育的差异, 包括语言任务中大脑语言区的激活模式, 静息状态下脑功能联结的默认网络特征, 脑皮层灰质密度, 以及神经纤维束发育状况等, 揭示早期语言经验对大脑功能和结构发育的塑造作用。     

文字阅读学习的大脑塑造性机制

文字阅读学习如何塑造了人脑?这是当今语言认知神经科学的热点课题。研究表明,文字阅读学习不仅会增强早期视觉加工能力和重构腹侧视觉通路,还改变了口语脑网络的加工方式和词素-音素转换脑网络的结构。文字阅读学习通过在视觉皮层与口语系统之间创建一个高效自动运作的平台,改变人脑的功能与结构组织。今后的研究需要深入探究视觉词形区(VWFA)的功能特异性及其与语音和语义加工的动态交互作用、汉字阅读学习的大脑可塑性机制和文字识别与面孔加工的竞争性发育机制等重要问题。     

统计学习与双语认知的关系

统计学习是提取环境输入潜在规则的一种认知机制,其与语言的关联已得到证实。双语认知是学界关注的热点之一。统计学习与双语认知的关系如何?文章先介绍统计学习认知机制及其与语言的关系,然后从“统计学习能力可否预测二语学习表现”、“统计学习训练能否促进二语学习”和“双语经验能否提高统计学习能力”三个维度述评相关文献,并指出未来可从输入特征、个体差异和神经科学角度进一步探讨统计学习与双语认知的关系。     

第二语言水平对双语者语言抑制能力的影响——来自英语–汉语单通道双语者和英语–美国手语双通道双语者的证据

采用同形异义词干扰任务考察第二语言水平对英语–汉语单通道双语者和英语–美国手语双通道双语者语言抑制能力的影响。结果发现:(1)高水平英语–汉语单通道双语者的语言抑制能力较强,但低水平英语–汉语单通道双语者与英语单语者的语言抑制能力没有显著差异,说明少量的双语经验不足以导致双语认知优势;(2)不同水平的英语–美国手语双通道双语者的语言抑制能力差异不显著。所以如此,与英语–美国手语双通道双语者不存在口语和手语的双语表征加工竞争有关。整个研究表明,双语认知优势效应与双语者的二语水平以及通道经验有关。     

Detecting structural and functional neuroplasticity in elite ice-skating athletes

Using resting-state fMRI, this study investigated long-term ice-skating training related changes in elite ice-skating athletes and compared them to healthy age-matched non-athletes under resting-state conditions. Significant differences were found in both structural and functional plasticity. Specifically, elite ice-skating athletes showed higher gray matter volume in the posterior cerebellum, frontal lobe, temporal lobe, posterior cingulate, caudate, and thalamus. The functional plasticity changes were primarily concentrated in the posterior cerebellar lobe. Additionally, stronger connectivity between the posterior cerebellar lobe and fusiform gyrus was also found in elite ice-skating athletes. Overall, the results are consistent with other studies that concluded long-term professional motor skill training can cause structural and functional plasticity in the regions of the brain related to motor planning, execution, and supervision. Both structural plasticity and functional plasticity are primarily enhanced in the posterior cerebellum. These changes may be related to the outstanding capability of speed and coordination caused by long-term ice-skating training. Present results add new evidence and may help us to understand the neural mechanisms of long-term motor skill training.     

Neurodynamic system theory: Scope and limits

This paper proposes that neurodynamic system theory may be used to connect structural and functional aspects of neural organization. The paper claims that generalized causal dynamic models are proper tools for describing the self-organizing mechanism of the nervous system. In particular, it is pointed out that ontogeny, development, normal performance, learning, and plasticity, can be treated by coherent concepts and formalism. Taking into account the self-referential character of the brain, autopoiesis, endophysics and hermeneutics are offered as elements of a poststructuralist brain (-mind-computer) theory.     

Plasticity of nonneuronal brain tissue: roles in developmental disorders

Neuronal and nonneuronal plasticity are both affected by environmental and experiential factors. Remodeling of existing neurons induced by such factors has been observed throughout the brain, and includes alterations in dendritic field dimensions, synaptogenesis, and synaptic morphology. The brain loci affected by these plastic neuronal changes are dependent on the type of experience and learning. Increased neurogenesis in the hippocampal dentate gyrus is a well-documented response to environmental complexity ("enrichment") and learning. Exposure to challenging experiences and learning opportunities also alters existing glial cells (i.e., astrocytes and oligodendrocytes), and up-regulates gliogenesis, in the cerebral cortex and cerebellum. Such glial plasticity often parallels neuronal remodeling in both time and place, and this enhanced morphological synergism may be important for optimizing the functional interaction between glial cells and neurons. Aberrant structural plasticity of nonneuronal elements is a contributing factor, as is aberrant neuron plasticity, to neurological and developmental disorders such as epilepsy, autism, and mental retardation (i.e., fragile X syndrome). Some of these nonneuronal pathologies include abnormal cerebral and cerebellar white matter and myelin-related proteins in autism; abnormal myelin basic protein in fragile X syndrome (FXS); and abnormal astrocytes in autism, FXS, and epilepsy. A number of recent studies demonstrate the possibility of using environmental and experiential intervention to reduce or ameliorate some of the neuronal and nonneuronal abnormalities, as well as behavioral deficits, present in these neurological and developmental disorders.     

Plasticity of brain and cognition in older adults

Aging is typically related to changes in brain and cognition, but the aging process is heterogeneous and differs between individuals. Recent research has started investigating the influence of cognitive and physical training on cognitive performance, functional brain activity, and brain structure in old age. The functional relevance of neural changes and the interactions among these changes following interventions is still a matter of debate. Here we selectively review research on structural and functional brain correlates of training-induced performance changes in healthy older adults and present exemplary longitudinal intervention studies sorted by the type of training applied (i.e., strategy-based training, process-specific training, and physical exercise). Although many training studies have been conducted recently, within each task domain, the number of studies that used comparable methods and techniques to assess behavioral and neural changes is limited. We suggest that future studies should include a multimodal approach to enhance the understanding of the relation between different levels of brain changes in aging and those changes that result from training. Investigating inter-individual differences in intervention-induced behavioral and neuronal changes would provide more information about who would benefit from a specific intervention and why. In addition, a more systematic examination of the time course of training-related structural and functional changes would improve the current level of knowledge about how learning is implemented in the brain and facilitate our understanding of contradictory results.     

A critical review of ERP and fMRI evidence on L2 syntactic processing

The current review focuses on recent event-related brain potential (ERPs) and functional magnetic resonance imaging (fMRI) in L2 syntactic processing data. To this end, critical factors influencing both the dynamics of neural mechanisms (ERPs) and critical functional brain correlates (fMRI) are discussed. These entail the critical period hypothesis, levels of proficiency, cross-linguistic syntactic similarities and dissimilarities as well as brain bases that may or may not be shared during syntactic processing in a first (L1) and a second (L2) language. The data to date reveal that (i) the critical period hypothesis plays less of a significant role than initially discussed, (ii) L2 proficiency is a driving factor influencing peak and extent of activation in brain correlates and in neurophysiological mechanisms as a function of learning, and (iii) language transfer effects (i.e., positive transfer effects when L1 and L2 are structurally similar or negative transfer effects when L1 and L2 are structurally dissimilar) primarily from the L1 to the L2 and potentially vice versa need to be critically considered in future research.     

Evolution of the neural language network

The evolution of language correlates with distinct changes in the primate brain. The present article compares language-related brain regions and their white matter connectivity in the developing and mature human brain with the respective structures in the nonhuman primate brain. We will see that the functional specificity of the posterior portion of Broca’s area (Brodmann area [BA 44]) and its dorsal fiber connection to the temporal cortex, shown to support the processing of structural hierarchy in humans, makes a crucial neural difference between the species. This neural circuit may thus be fundamental for the human syntactic capacity as the core of language.     

MAP2 and synaptophysin protein expression following motor learning suggests dynamic regulation and distinct alterations coinciding with synaptogenesis

Learning a new motor skill can induce neuronal plasticity in rats. Within motor cortex, learning-induced plasticity includes dendritic reorganization, synaptogenesis, and changes in synapse morphology. Behavioral studies have demonstrated that learning requires protein synthesis. It is likely that some of the proteins synthesized during learning are involved in, or the result of, learning-induced structural plasticity. We predicted the expression of proteins involved in neural plasticity would be altered in a learning dependent fashion. Long-Evans rats were trained on a series of motor tasks that varied in complexity, so that the effects of activity could be teased apart from the effects of learning. The motor cortices were examined for MAP2 and synaptophysin protein using Western blotting and immunohistochemistry. Western blotting revealed that expression of MAP2 was not detectably influenced by learning, whereas synaptophysin expression increased on day 1, 3, and 5 of complex motor skill learning. Expression of MAP2 does not seem to indicate difficulty of task or duration of training time, whereas increases in synaptophysin expression, which appear diffusely across the cortex, seem to be correlated with the first 5 days of motor skill learning. Similar findings with GAP-43 suggest the change in synaptophysin may coincide with synapse formation. Immunohistochemistry did not reveal any localized changes in protein expression. These data indicate a difference in learning-induced expression in the mammalian brain compared to reports in the literature, which have often focused on stimulation to induce alterations in protein expression.     

Neural network processing of natural language: II. Towards a unified model of corticostriatal function in learning sentence comprehension and non-linguistic sequencing

A central issue in cognitive neuroscience today concerns how distributed neural networks in the brain that are used in language learning and processing can be involved in non-linguistic cognitive sequence learning. This issue is informed by a wealth of functional neurophysiology studies of sentence comprehension, along with a number of recent studies that examined the brain processes involved in learning non-linguistic sequences, or artificial grammar learning (AGL). The current research attempts to reconcile these data with several current neurophysiologically based models of sentence processing, through the specification of a neural network model whose architecture is constrained by the known cortico-striato-thalamo-cortical (CSTC) neuroanatomy of the human language system. The challenge is to develop simulation models that take into account constraints both from neuranatomical connectivity, and from functional imaging data, and that can actually learn and perform the same kind of language and artificial syntax tasks. In our proposed model, structural cues encoded in a recurrent cortical network in BA47 activate a CSTC circuit to modulate the flow of lexical semantic information from BA45 to an integrated representation of meaning at the sentence level in BA44/6. During language acquisition, corticostriatal plasticity is employed to allow closed class structure to drive thematic role assignment. From the AGL perspective, repetitive internal structure in the AGL strings is encoded in BA47, and activates the CSTC circuit to predict the next element in the sequence. Simulation results from Caplan's [Caplan, D., Baker, C., & Dehaut, F. (1985). Syntactic determinants of sentence comprehension in aphasia. Cognition, 21, 117-175] test of syntactic comprehension, and from Gomez and Schvaneveldts' [Gomez, R. L., & Schvaneveldt, R. W. (1994). What is learned from artificial grammars?. Transfer tests of simple association. Journal of Experimental Psychology: Learning, Memory and Cognition, 20, 396-410] artificial grammar learning experiments are presented. These results are discussed in the context of a brain architecture for learning grammatical structure for multiple natural languages, and non-linguistic sequences.