文盲文字加工的行为和脑机制

文盲作为一个特殊的被试群体,对其的研究一直备受关注。文盲研究最初集中在文盲的口语加工和语音意识等方面。其后比较关注文盲字词的语音和语义加工。随着脑成像技术的发展,对文盲的文字加工脑认知机制进行了研究,探讨脑功能组织是如何受到早期学习的调制,左侧梭状回在字词识别中的作用及其文盲脑功能偏侧化问题。以后此类研究应关注文盲字词识别学习过程中的脑功能变化和文化认知对认知老化的影响等科学问题。     

面孔识别中脑电成分N170的研究概述

N170是在面孔刺激呈现后的130-200ms记录到的并在160~170ms时达到峰值的一种脑电负成分。目前, 在N170的研究中存在争议性的问题有：N170反映面孔结构编码还是面孔特征编码; N170是否是面孔特异性成分; 以及N170是否受注意的影响等。这些争议也为N170后续研究指明了方向, 即探讨结构编码和特征编码在诱发N170成分上起着怎样的作用; 比较不同熟悉度的刺激材料所诱发的N170反应差异; 探讨N170成分与识别电位间的关系;采用多研究方法的结合从不同层面深入揭示N170的认知机制。     

羞怯与非羞怯大学生在早期面孔加工中的差异——来自ERP的电生理学证据

羞怯与社会认知密切相关,而面孔识别是人们社会生活中的一项重要的社会认知功能。目前关于羞怯的电生理学研究大多关注表情的效价效应和面孔的新旧效应对羞怯个体面孔加工的影响,却忽视了羞怯个体在基本的面孔识别能力——面孔-物体识别中可能存在的认知神经差异。因此,本研究采用ERP技术,使用GO/Nogo范式的面孔-物体识别任务,对17名羞怯大学生和17名非羞怯大学生在面孔结构编码中的N170成分进行考察,以期发现不同羞怯水平大学生在早期面孔加工中的认知神经差异。本研究发现,非羞怯大学生对面孔结构具有加工优势,识别面孔时,非羞怯大学生的N170波幅显著大于羞怯大学生的N170波幅,识别物体时则不存在组间差异;N170是面孔识别的特异性成分,面孔诱发的N170波幅显著大于物体诱发的N170波幅;识别面孔时,N170表现出大脑右半球的加工优势。     

汉字识别中亚词汇语音和语义信息在N170上的神经适应

视觉词汇识别的事件相关电位(ERP)研究发现早期的脑电成分N170具有对词汇的敏感性, 可能反映了字形、语音和语义加工, 目前还没有得到统一的结论。本研究利用汉字形声字声旁表音和形旁表义的独特性, 使用神经适应范式深入考察了N170对汉字亚词汇语音和语义信息的敏感性。实验1操纵了连续汉字的声旁和整字读音重复呈现探究其诱发的神经适应性, 结果发现了左侧电极的N170对声旁和整字读音重复都产生了神经适应。实验2进一步操纵形旁和整字语义的重复呈现, 结果发现左侧N170仅对整字语义相似性具有神经适应性, 而右侧N170对形旁和整字语义重复都产生了神经适应。实验结果表明, 左侧N170不仅对整字语音和语义信息敏感, 还对亚词汇的声旁信息敏感; 而右侧N170对整字语义以及亚词汇的形旁信息敏感。     

归纳推理的认知神经机制

归纳推理是从特殊推导至一般的高级认知过程, 其认知神经机制是当前研究的新方向。对已有研究进行分析发现：(1)归纳推理的核心过程与前额叶和晚期ERP成分密切相关; (2) 归纳推理可能存在双系统; (3)归纳推理过程中大脑偏侧化的现象存在争议。以上三个问题需要后续归纳推理的认知神经机制研究进行验证。     

躯体表情与面部表情加工进程比较

躯体和面孔是个体情绪识别的敏感线索。与面部表情的早期视觉加工相似, P1成分对恐惧、愤怒等负性躯体表情更加敏感, 反映了对躯体威胁信息快速且无意识的加工。情绪躯体和面孔还有着类似的构型加工, 表现为二者都能诱发颞枕区视觉皮层相似的N170成分, 但涉及的神经基础并不完全相同。在构型编码加工中, 面部表情的N170与顶中正成分(Vertex Positive Potential, VPP)较躯体表情的N170、VPP更加明显。在面部表情和躯体表情的后期加工阶段, 早期后部负波(Early Posterior Negativity, EPN)反映了面孔和躯体视觉编码的注意指向加工, 随后出现的P3与晚期正成分(Late Positive Component, LPC)代表了顶额皮层对复杂情绪信息的高级认知加工。躯体表情还存在与外纹状皮层躯体区相关的N190成分, 其对躯体的情绪和动作信息敏感。今后的研究应进一步探讨动作对情绪知觉的影响、动态面孔−躯体情绪的加工机制等。     

面孔类别识别的N170和VPP的时空特异性研究

对面孔刺激敏感的ERP成分N170,其特异性至今仍有争论。本研究记录正立脸、倒置脸、动物脸、马赛克脸及七类物体类别图片刺激的ERP,分析ERP成分的峰值和潜伏期。正立脸比倒置脸、动物脸所引出的N170的峰值和潜伏期都高和早。其他类别刺激引出N170,其潜伏期早于脸刺激,峰值低于脸刺激。正立脸和动物脸VPP潜伏期显著长于其他类别刺激,之间没有差异显著性。脸刺激与其他物体类别刺激相比,N170和VPP是其特异性的脑波成分。     

声调的脑机能偏侧化研究

语言的机能偏侧化研究是神经心理学研究的主要任务之一,以往研究对象大多是非声调语言。汉语 是声调语言,其脑机能偏侧化有许多特点,对正常人的声调偏侧化研究结论不一,对语言障碍病人 的声调偏侧化研究大多认为两半球均势。我们通过对三例纯词哑患者的语言分析,左半球损伤对声 调的影响很小,其原因可能由于声调既是一种语言学信号,又有音乐的特点,具有两重性,对其控 制两半球皮层均有作用。     

利手与语言功能偏侧化的遗传模型

利手与语言功能偏侧化现象不仅具有跨文化一致性和发生、发展上的关联性, 还具有明显的生态学优势, 从遗传角度探讨它们的成因是必要的。早期遗传模型认为, 存在一对等位基因分别决定左、右利手。当代单基因模型则将语言功能偏侧化也纳入进来, 认为等位基因不仅可以决定具有方向性的偏侧化, 而且可以使偏侧化有一定几率向左或向右。在这个框架下形成了方向-随机等位基因模型、X-连锁隐性基因模型和右侧位移理论, 它们对等位基因的位置和功能有不同表述, 对利手的划分标准、性别差异以及遗传和环境的关系也有不同阐释。今后需加强对语言偏侧化的数据验证, 进一步阐明语言感知、理解与利手的关系, 并注重基因怎样决定表型、基因多效性和多基因合作等问题的研究。     

高度模糊靶字下的N400语义启动效应：词汇加工理论的证据

本研究基于不可识别模糊字词仍能诱发N400的词汇加工理论的假设,让被试对模糊字进行同一字延迟判断,利用脑电技术记录不同模糊程度靶字的认知过程,来探讨N400出现的条件,以阐明N400反映的是词汇加工,还是词汇后加工。实验结果表明：与可识别、轻度模糊汉字一样,不可识别、高度模糊汉字仍然可以诱发N400;这种N400语义启动效应反映了词汇加工过程。     

词汇具体性对情绪名词效价加工影响的ERP研究

具体性和抽象性是词汇同一特性的两极, 是直接影响词汇加工过程的重要因素。本研究采用快速序列视觉呈现范式, 结合脑电技术探讨在有限注意资源内, 词汇具体性对情绪名词加工过程的影响。结果发现：名词加工早期和晚期阶段的ERP成分受到情绪效价的调节, 情绪词比中性词诱发了更大的N170和LPC波幅; 名词加工早期和晚期阶段的ERP成分也受到词汇具体性的调节, 具体词比抽象词诱发了更大的N170和LPC波幅; 词汇具体性影响情绪名词加工的晚期阶段, LPC波幅能够分辨出不同情绪效价的抽象词, 对于具体词仅能区分出情绪与非情绪, 这说明抽象词可能比具体词负载了更多的情绪信息, 反映出对情绪信息的精细加工过程。     

Using event-related potentials to examine hemispheric differences in semantic processing

Event-related potentials (ERPs) were used as the dependent measure in a divided visual field study examining the processing of lexically ambiguous words in the cerebral hemispheres. The goal was to determine if the N400 ERP component is sensitive measure of hemispheric differences in semantic processing. ERP waveforms were examined for lateralized target words that were related to either the dominant (MONEY) or subordinate (RIVER) meanings of ambiguous words (BANK). These waveforms were compared to trials where the prime-target pairs were unrelated. Reliable N400s, reflecting a significant difference between related and unrelated trials, were seen when targets were presented to the right visual field/left hemisphere. However, there were no N400s observed for either the dominant or subordinate conditions when targets were presented to the left visual field/right hemisphere.     

Domain specificity versus expertise: factors influencing distinct processing of faces

To explore face specificity in visual processing, we compared the role of task-associated strategies and expertise on the N170 event-related potential (ERP) component elicited by human faces with the ERPs elicited by cars, birds, items of furniture, and ape faces. In Experiment 1, participants performed a car monitoring task and an animacy decision task. In Experiment 2, participants monitored human faces while faces of apes were the distracters. Faces elicited an equally conspicuous N170, significantly larger than the ERPs elicited by non-face categories regardless of whether they were ignored or had an equal status with other categories (Experiment 1), or were the targets (in Experiment 2). In contrast, the negative component elicited by cars during the same time range was larger if they were targets than if they were not. Furthermore, unlike the posterior-temporal distribution of the N170, the negative component elicited by cars and its modulation by task were more conspicuous at occipital sites. Faces of apes elicited an N170 that was similar in amplitude to that elicited by the human face targets, albeit peaking 10 ms later. As our participants were not ape experts, this pattern indicates that the N170 is face-specific, but not specie-specific, i.e. it is elicited by particular face features regardless of expertise. Overall, these results demonstrate the domain specificity of the visual mechanism implicated in processing faces, a mechanism which is not influenced by either task or expertise. The processing of other objects is probably accomplished by a more general visual processor, which is sensitive to strategic manipulations and attention.     

启动效应的ERP研究综述

近年来,国内外学者以ERP为工具,对启动效应进行了不少研究,并得到一些有意义的结果。例如,在知觉启动方面,发现视觉运动启动的神经机制不同于其它知觉型启动,它既涉及视觉加工的较早阶段,也涉及到较晚阶段。再如,词的重复效应不同于物体的重复效应等等。关于语义型启动的ERP研究,主要围绕N400和N450进行。本文对该领域的一些重要研究进行了介绍和总结,并对该领域中的一些基本研究范式问题进行了讨论。     

Deficits in early-stage face perception in excessive internet users

Excessive Internet use is associated with a limited ability to communicate effectively socially, which depends largely on the capacity for perception of the human face. We used a passive visual detection paradigm to compare the early stages of the processing of face-related information in young excessive Internet users (EIUs) and healthy normal subjects by analyzing event-related potentials (ERPs) elicited by faces and by nonface stimuli (tables), each presented in the upright and inverted position. The P1 and N170 components of the spectrum of ERPs elicited at occipital-temporal sites by the viewing of faces were larger and peaked sooner than the same ERP components elicited by tables, and inverted faces significantly enhanced and delayed the N170 component. EIUs had a generally smaller P1 component than did normal subjects, whether elicited by faces or by tables, and the N170 effect, or difference in amplitude of the N170 component for faces versus tables, was significantly smaller in the EIUs than in normal subjects. However, the N170 inversion effect, or difference in amplitude of the N170 component elicited by upright versus inverted faces, was similar in the EIUs and normal subjects. These data indicate that EIUs have deficits in the early stage of face-perception processing but may have intact holistic/configural processing of faces. Whether some deeper processes of face perception, such as face memory and face identification, are affected in EIUs needs to be investigated further with more specific procedures.     

Task-dependent modulation of word processing mechanisms during modified visual search tasks

During visual search for words, the impact of the visual and semantic features of words varies as a function of the search task. This event-related potential (ERP) study focused on the way these features of words are used to detect similarities between the distractor words that are glanced at and the target word, as well as to then reject the distractor words. The participants had to search for a target word that was either given literally or defined by a semantic clue among words presented sequentially. The distractor words included words that resembled the target and words that were semantically related to the target. The P2a component was the first component to be modulated by the visual and/or semantic similarity of distractors to the target word, and these modulations varied according to the task. The same held true for the later N300 and N400 components, which confirms that, depending on the task, distinct processing pathways were sensitized through attentional modulation. Hence, the process that matches what is perceived with the target acts during the first 200?ms after word presentation, and both early detection and late rejection processes of words depend on the search task and on the representation of the target stored in memory.