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。     

人声加工的神经机制

人声是人类听觉环境中最熟知和重要的声音, 传递着大量社会相关信息。与视觉人脸加工类似, 大脑对人声也有着特异性加工。研究者使用电生理、脑成像等手段找到了对人声有特异性反应的脑区, 即颞叶人声加工区(TVA), 并发现非人类动物也有类似的特异性加工区域。人声加工主要涉及言语、情绪和身份信息的加工, 分别对应于三条既相互独立又相互作用的神经通路。研究者提出了双通路模型、多阶段模型和整合模型分别对人声的言语、情绪和身份加工进行解释。未来研究需要进一步讨论人声加工的特异性能否由特定声学特征的选择性加工来解释, 并深入探究特殊人群(如自闭症和精神分裂症患者)的人声加工的神经机制。     

文本阅读认知神经科学研究进展

功能磁共振成像等认知神经科学技术被广泛引入文本阅读的认知神经活动研究以来,其成果有力地促进了文本阅读信息加工过程研究的深入发展。本文系统总结了近二十余年关于文本阅读的认知神经科学研究进展,分别介绍文本阅读的一般过程的认知神经基础和理论模型建构、文本阅读过程的推理加工、情境模型建构与转换三个主要研究领域的研究成果,并对文本阅读的认知神经研究的现状及其存在的问题进行了总结。     

加工需求驱动下词汇阅读神经通路的动态协作机制

建构统一的认知和神经生理模型是词汇阅读认知神经科学研究面临的核心问题。阅读的认知理论模型一致认为阅读是语音和语义加工通路分工协作的结果,认知神经科学研究也表明词汇阅读是背侧和腹侧神经通路动态协作的结果。为了系统地阐述阅读网络的这种动态协作机制,结合神经功能和生理基础两个层面,从以下三个方面对最新研究进展进行系统疏理：首先,指出潜在的加工需求是背/腹侧神经通路动态协作的实质;然后进一步阐明潜在加工需求驱动了不同正字法深度下背/腹侧神经通路的分工合作模式;最后,深入剖析了潜在加工如何通过语言经验塑造了神经通路间的动态协作。从而揭示出阅读神经通路动态协作的实质可能是特定任务下加工需求驱动的结果,这种动态协作可能成为跨语言普遍的词汇阅读理论模型。     

视觉恐惧加工的神经通路

对危险信号的快速警觉具有生物学意义,研究发现视觉恐惧信号可以经过两条不同的通路传达杏仁核:一条直接的皮层下通路,另一条是间接的视觉皮层通路.最近三年(2004-2006)一批脑成像和电生理研究对此进行了深入探讨.本文以此为基础对两条通路的主要神经结构,神经传递的先后过程以及它们间的关系进行了详细的综述.     

发展性阅读障碍风险儿童的大脑异常及阅读障碍的早期神经标记

考察发展性阅读障碍风险儿童的神经异常有助于找到阅读障碍的早期神经标记物,对实现阅读障碍早期预测和干预具有重要意义。基于风险儿童的横向研究显示,其大脑的功能和结构存在异常。具体表现在风险儿童感知语音及非语音诱发的失匹配波(MMR,MismatchResponse)波幅更小,潜伏期更长,在阅读的腹侧和背侧通路功能和结构存在异常。相比于学龄前横向比较,追踪到学龄后的研究可以发现与阅读发展相关的神经变化,揭示阅读障碍的早期神经标记。纵向研究显示,语音加工诱发的MMR、左侧颞顶区、视觉词形区功能异常及左侧弓状束结构异常是阅读障碍的早期生物学标记。此外,风险儿童大脑异常的纵向研究相对稀少,同时较小的样本量也会降低结果的可信度。未来需要强调更大样本量的纵向研究,同时关注汉语风险儿童的大脑异常,探究汉语阅读障碍认知神经风险因素的特殊性和普遍性。     

数字加工的脑功能成像研究进展及其皮层定位

数字加工是人类最重要的认知功能之一。当前的脑功能成像研究有助于对数字加工与皮层之间的联系进行更精确的定位。基于对上世纪80年代来有关数字加工脑功能成像研究的主要成果的回顾,尤其是一些重要区域,如双侧顶叶与前额叶等在数字加工中的地位与作用,以及不同脑区之间的关系进行了探讨,并对一个广泛运用的数字加工神经机制模型进行了简要评述。在此基础上,对数字加工的皮层定位问题进行了简要的总结。     

句子加工的脑成像研究

近年来句子加工的脑成像研究大量涌现,并集中于揭示句子语义与语法加工的神经机制以及之间的联系。文章首先对这些研究所采用的范式加以分析与比较,从而将句子加工脑成像研究的研究思路与常用范式进行了归纳与总结。其次,讨论了语义加工与语法加工的神经机制,并根据现有的研究结果,对句子语义与语法两个成分在认知加工与神经机制上的共性与特性做出推论。最后,从语言的多样性以及影响句子加工的因素两个角度,对以后的句子加工脑成像研究做了展望。     

应用动态因果模型研究阅读神经网络背、腹侧通路的协作机制

在神经网络的最新取向下, 探讨阅读脑机制中背侧和腹侧通路的协作机制, 是解决语言认知神经科学多个理论问题共同面临的焦点。本项目拟通过两个脑功能成像实验, 建构汉字阅读的动态因果模型, 系统地考察汉字阅读的神经网络, 以及阅读网络中背、腹侧通路的协作机制。实验一利用快速适应实验范式的优点, 识别和考察汉字阅读涉及的认知成分所对应的功能脑区, 以及脑区联结形成的神经回路, 并建构汉字阅读的动态因果模型; 实验二进一步考察在刺激属性(语音和语义信息)和任务要求下阅读脑区的动态激活及相互作用。通过不同任务下的模型对比, 重点探讨阅读网络的脑区联结模式变化, 尤其是背、腹侧通路受刺激和任务影响时的协作机制。研究结果将为揭示阅读的神经生理模型、解决语言特异性脑区激活的争论等理论问题提供直接的证据, 还能为语言教学、阅读障碍矫治、以及临床应用提供理论基础与指导。     

学习技能形成中的脑加工

对运动学习,视知觉学习,镜像阅读,语法学习和动词产生学习的脑实验研究,主要有单通路调节加工模型和双通路转换加工模型,实验侧重研究学习的时间进程。     

汉语双字词在心理词典中的表征方式:来自fNIRS的证据

以汉语双字构成的真词与假词为实验材料,22名大学生为被试,采用功能性近红外脑成像技术(f NIRS)和事件相关设计,考察被试在完成词汇判断任务时的大脑激活模式,探索汉语双字词在心理词典中的表征方式。结果发现:(1)在完成真假词判断任务时,被试大脑左侧额叶和左侧颞叶均被激活;(2)与判断假词相比,被试在判断真词时显著地激活左额上回和左额中回。这一结果说明汉语双字词在心理词典中是混合表征的。     

发展性阅读障碍的视觉空间注意加工能力

鉴于阅读起始于基础视觉加工阶段, 越来越多的研究者开始关注阅读障碍者的视觉空间注意加工能力。视觉空间注意是指个体对视觉刺激的空间位置的注意, 可通过线索提示、视觉搜索和视觉注意广度等视觉任务来考察。大量国内外研究发现, 发展性阅读障碍者在视觉空间注意任务下表现出行为和神经活动方面的异常。其中的神经机制问题不仅反映在与视觉空间注意有关的顶叶区域激活异常, 还存在于脑区间功能连接异常(如顶叶区域与字形加工区的功能连接)。未来研究还需利用横断和追踪研究探讨阅读障碍与视觉空间注意能力发展关系的内在机制, 以及探究语言特性对阅读障碍者视觉空间注意缺陷的可能调节作用。     

发展性阅读障碍书写加工缺陷及其神经机制

发展性阅读障碍是学习障碍的主要类型之一, 严重影响个体认知、情感与社会适应性的发展。书写与阅读关系密切, 阅读障碍者常常表现出书写加工缺陷。在行为层面, 阅读障碍者书写缺陷表现在书写质量差、速度慢和停顿多等多个方面。在脑机制层面, 脑成像研究发现, 阅读障碍者书写加工缺陷与字形加工脑区活动, 以及字形与运动区脑功能与结构连接异常有关。总体而言, 阅读障碍者书写过程中的字形通达缺陷的证据比较充分, 但字形与运动编码的衔接以及运动执行是否存在困难, 尚缺乏研究证据。相对于字母语言, 书写与阅读的关系在汉语中更为紧密, 汉语阅读障碍的书写研究将为开发汉语特色的诊治方案提供重要指导。     

Adult age differences in visual word identification: functional neuroanatomy by positron emission tomography

Adult age differences in the neural systems mediating semantic (context-independent) memory were investigated using positron emission tomography (PET). Younger (20-29 years) and older (62-70 years) participants performed lexical decision (word/nonword discrimination) and nonsemantic (simple visual search) baseline tasks during PET scanning. Within the lexical decision task, display duration and presentation rate were varied across scans. The behavioral data suggested that although an age-related slowing was evident in visual feature and response processing, the retrieval of semantic/lexical information was similar for younger and older adults. For both age groups, lexical-related activation occurred in inferior prefrontal and occipitotemporal regions of the left hemisphere. Differential activation, as a function of age group, was observed in the left occipitotemporal pathway as a result of older adults' maintaining higher levels of neural activity in striate cortex (during visual search) and in inferior temporal cortex (during lexical decision). The prefrontal activation was similar for the two age groups. Thus, although this form of semantic memory retrieval does not undergo significant age-related decline, an age-related change in the associated pattern of neural activation is evident. These findings differ from previous neuroimaging studies of episodic (context-dependent) memory retrieval, which have suggested that age-related compensatory mechanisms are expressed primarily by greater activation of prefrontal regions for older adults than for younger adults.     

Right hemisphere semantic processing of visual words in an aphasic patient: an fMRI study

This study was designed to identify the neural network supporting the semantic processing of visual words in a patient with large-scale damage to left-hemisphere (LH) language structures. Patient GP, and a control subject, RT, performed semantic and orthographic tasks while brain-activation patterns were recorded using functional magnetic resonance imaging. In RT, the semantic-orthographic comparison activated LH perisylvian and extrasylvian temporal regions comparable to the network of areas activated by non-brain-damaged subjects in other neuroimaging studies of semantic discrimination. In GP, the same comparison activated homologous right-hemisphere regions, demonstrating the ability of the right hemisphere to subserve visual lexicosemantic processes. The results are discussed within the context of the normal right hemisphere's capacity for semantic processing of visual words. Examining results from functional neuroimaging studies on recovery in the context of innate hemispheric abilities may enable reconciliation of disparate claims about mechanisms supporting recovery from aphasia.     

The role of inferior frontal cortex in phonological processing

Recent neuroimaging studies of language processing are examining the neural substrate of phonology because of its critical role in mapping sound information onto higher levels of language processing (e.g., words) as well as providing codes in which verbal information can be temporarily stored in working memory. However, the precise role of the inferior frontal cortex in spoken and written phonological tasks has remained elusive. Although lesion studies have indicated the presence of selective deficits in phonological processing, the location of lesions underlying these impairments has not revealed a consistent pattern. Despite efforts to refine methods and tasks, functional neuroimaging studies have also revealed variability in activation patterns. Reanalysis of evidence from these neuroimaging studies suggests that there are functional subregions within the inferior frontal gyrus that correspond to specific components of phonological processing (e.g., orthographic to phonological conversion in reading, and segmentation in speech).     

视觉词汇加工的动态神经网络及其形成

揭示大脑加工的神经网络机制成为认知神经科学研究的最新取向.本研究以视觉词汇加工脑区(VWFA)的神经功能作为切入点,探讨视觉词汇加工神经网络的动态机制及其形成.研究一考察VWFA在刺激驱动和任务调节下的动态激活,及其与语音、语义脑区所组成神经网络的动态机制.研究二通过跨文化对比以及儿童阅读发展研究,阐明语言经验对视觉词汇加工网络的塑造作用.研究三对比功能网络、静息网络以及白质纤维束联结,探讨视觉词汇加工网络的动态联结及其形成.研究结果有助于建构视觉词汇加工的神经生理模型,为基于脑科学的阅读教学和阅读障碍矫治奠定理论基础,为认知神经科学研究提供了新的思路.     

Strategic regulation of cognitive control by emotional salience: A neural network model

We present a neural network model of stimulus processing, which uses a mechanism of adaptive attentional control to regulate the moment to moment deployment of attention according to both the demands of the current task, and the demands of emotionally salient information. This mechanism allows negative emotional information to reduce cognitive control to aid in the detection of threats, which produces a momentary withdrawal from the current task set to allow unbiased processing of available information. The combination of cognitive and emotional regulation of task set allows this model to address inter-trial aspects of emotional interference in colour naming. In particular, we focus on the nature of the emotional interference in colour naming (McKenna & Sharma, 2004) as well as in word reading (Algom, Chajut, & Lev, 2004) and show how this form of interference is functionally distinct from the classic Stroop effect. Our model addresses a range of findings in colour naming and word reading tasks and is informed by recent neuroimaging data concerning the interaction between the anterior cingulate and prefrontal cortices. The model is used to explore the interface between cognition and emotion with a series of predictions, including a qualitative distinction between state and trait forms of anxiety.     

Cortical localisation of the visual and auditory word form areas: a reconsideration of the evidence

In this paper we examine the evidence for human brain areas dedicated to visual or auditory word form processing by comparing cortical activation for auditory word repetition, reading, picture naming, and environmental sound naming. Both reading and auditory word repetition activated left lateralised regions in the frontal operculum (Broca's area), posterior superior temporal gyrus (Wernicke's area), posterior inferior temporal cortex, and a region in the mid superior temporal sulcus relative to baseline conditions that controlled for sensory input and motor output processing. In addition, auditory word repetition increased activation in a lateral region of the left mid superior temporal gyrus but critically, this area is not specific to auditory word processing, it is also activated in response to environmental sounds. There were no reading specific activations, even in the areas previously claimed as visual word form areas: activations were either common to reading and auditory word repetition or common to reading and picture naming. We conclude that there is no current evidence for cortical sites dedicated to visual or auditory word form processing.