正常成人汉语句子识别的事件相关脑电位N400实验研究

目的探讨正常成人汉语句子结尾词匹配和非匹配事件相关脑电位（ERP）N400的特点。方法应用ERP仪,对58名19～63岁正常成人右利手受试者,进行汉语正常句子结尾词（匹配）与句子结尾歧义词（非匹配）N400的实验研究。结果正常成人中央区（Cz）、前额区（Fz）及顶区（Pz）脑区汉语句子结尾词匹配的N400平均潜伏期为364ms,平均波幅为8.9μV;非匹配的N400的平均潜伏期为409ms,平均波幅为12.9μV。正常成人各脑区匹配与非匹配的汉语句子结尾词的N400潜伏期、波幅比较有统计学差异。结论正常成人汉语句子识别的N400稳定、可靠;非匹配的汉语句子结尾词的N400潜伏期长,波幅高。     

事件相关脑电位N400在精神科的应用

目的取得本实验室的事件相关脑电位(ERP)-N400实验方法。方法应用中国广州润杰WJ-1型ERP仪,对46名20～54岁右利手正常成人受试者和38名精神分裂症患者,进行汉语成语正常结尾(匹配)与成语结尾歧义词(不匹配)的N400基本波型研究。结果(1)正常成人N400波形较稳定。(2)波形分析所见,结尾词不匹配组的N400较匹配组潜伏期较长,波幅高。(3)精神分裂症组N400潜伏期延长和波幅下降。结论正常成人N400是可靠的,可作为一个有临床价值的ERP而用于精神分裂症及伴有语言障碍疾病的评估。     

儿童抽动障碍事件相关电位N400的研究

目的探讨儿童抽动障碍患者事件相关电位N400的变化及其意义。方法用诱发电位检测仪测定35例抽动障碍患儿(病例组)的N400,并与20名正常儿童(正常对照组)进行比较。结果病例组N400的潜伏期为(706.87±198.99)ms,波幅为(26.12±13.64)μV,对照组为(485.75±85.76)ms和(22.35±19.76)μV。两组潜伏期比较,差异有非常显著性(P<0.001);波幅比较,差异无显著性(P>0.05)。结论抽动障碍患者的事件相关电位N400潜伏期明显延长,显示其存在认知功能障碍。     

事件相关电位N400神经发生源研究

目的事件相关电位(event-related potentials,ERPs)N400是与语境歧义处理相关的高级认知电位,研究应用于精神分裂症的认知功能障碍。有关N400神经发生源,国内外均少有研究报道。本研究应用“低分辩率电磁断层扫描术(low resolution electromagnetic tomography,LORETA)”技术研究 N400的神经发生源。方法ERPs应用汉词语词对(S1-S2)诱发。S1-S2的关系为:语义关联对、语义非关联对和汉词-人造词对。脑电信号应用17导电极记录。被试为18例正常健康者,男9,女9,平均年龄25．2±4．4岁。应用LORETA软件中内含的“统计学非参数地形图(statistical non-parametric mapping,SnPM)”程序分析被试处理不同类语词时所激活的脑功能区差异。结果与语义关联词对中S2诱发ERPs相比,语义非关联词对中S2诱发出潜伏期在300-500 ms左右的负向偏转成分N400。分别比较S2开始后300-350 ms、350-400 ms、400-450 ms和450-500 ms时间窗内两类刺激语词激活的脑功能区,发现具有显著性差异的脑功能区集中在左半球的颞上回、颞中回、岛回、梭状回、后扣带回和海马旁回等区域。结论事件相关电位N400的神经发生源位于优势半球的颞叶及扣带回-海马结构。     

健康成人汉语成语尾字识别的N400研究

目的研究健康成人汉语成语尾字匹配与非匹配N400的变化。方法入选35名20～55岁健康成人右利手受试者,进行汉语成语匹配与非匹配N400的实验研究。结果 N400基本波型分布于Fz、Cz和Pz等脑区。分别获得健康成人同音异形异义、异音形似异义、异音异形同义及异音异形异义汉语成语尾字匹配与非匹配的N400潜伏期和波幅平均值。结论汉语成语尾字匹配和非匹配N400的改变与字词认知中的语义有关。     

注意缺陷多动障碍患儿事件相关电位N400研究

目的:探讨注意缺陷多动障碍(ADHD)患儿汉语句子结尾词匹配和非匹配语言时相关电位(ERP)N400的变化。方法:应用ERP仪,采用汉语正常句子结尾词匹配与非匹配的范式,对35例ADHD患儿(ADHD组)和41名正常儿童(正常对照组)进行视觉诱发电位N400检测。结果:在Cz脑区匹配及非匹配条件下,ADHD组N400潜伏期[(384±45)ms,(436±35)ms]比正常对照组[(348±32)ms,(399±29)ms]显著延迟(P均0.01);波幅ADHD组[(4.2±4.5)μV,(7.5±5.1)μV]显著低于正常对照组[(7.6±5.0)μV,(12.4±6.5)μV](P均0.01)。结论:ADHD患儿N400异常,N400检测可能成为判断注意缺陷多动障碍的客观指标。     

卒中患者大脑半球语言认知N400差异性研究

目的:探讨脑卒中患者两半球语言认知N400差异性。方法:对20例首发单病灶脑卒中患者（其中左半球损伤者9例,右半球损伤者11例）和20例无脑损害的患者/健康体检者进行N400实验。比较两组N400差异波潜伏期、波幅的差异。结果:右半球损伤者较对照组Fz、Pz、T4点潜伏期延长,T4点波幅降低。右半球损伤者较左半球损伤者,Pz点潜伏期延长,反应时延长。结论:大脑右半球可能参与汉语言认知加工过程。     

采用事件相关电位研究汉字的识别过程—基于形音义的初步研究

当启动记号与靶词在形不匹配时，受试者的ＥＲＰｓ均出现一个较大的负相成分。在音义分类作业时，Ｎ４００的潜伏较长，波幅较大，左右两侧波幅不对称的现象较为明显。而在定形分类作业时，Ｎ４００潜伏期较短，波幅较低，左右两侧波幅无显著性差异。提示，字形加工和音，义的加工可能具有不同的脑机制。Ｎ４００的潜伏期与波幅可能与对字词的加工深度有关。     

脑波治疗对精神分裂症患者认知损害的汉语句子N400影响

目的 探讨脑波治疗对精神分裂症患者汉语句子事件相关电位N400的影响.方法 随机将年龄在18～60岁符合CCMD-3精神分裂症标准患者60例分为单纯应用奥氮平治疗组(实验组1,n=30)及应用脑波联合臭氮平治疗组(实验组2,n=30),选择30例健康者作为对照组.实验组予奥氮平治疗8周前后予＜简明精神状况检查量表＞(BPRS)评分,各组分别予N400检测,分别比较N400潜伏期及波幅的差异.结果 实验组1、实验组2 Pz点潜伏期均比对照组延长,波幅均比对照组降低(P＜0.05及0.01).治疗后,实验组1、实验组2 Fz点潜伏期均比治疗前缩短,波幅均比治疗前升高(P＜0.05及0.01).实验组2 Pz点潜伏期比实验组1缩短,波幅均比实验组1升高(P＜0.05及0.01).治疗后BPRS评分.实验组1高于实验组2(P＜0.01),实验组2显效率及总有效率明显高于实验组1(P＜0.01).结论 脑波治疗通过调节、平衡人体的脑电活动及兴奋水平,具有辅助改善精神分裂症患者认知功能的作用.     

奥氮平对青少年精神分裂症患者认知损害的汉语句子N400的影响

我们于2004年11月至2006年1月对青少年精神分裂症患者进行了汉语句子N400检测。对象 为本院住院及门诊患者。入组标准：年龄12～18岁，符合美国精神障碍诊断与统计手册第4版精神分裂症诊断标准、监护人知情同意并合作。排除有脑部及躯体疾病史、2周内使用影响认知功能的药物、既往有精神活性物质使用史以及电休克治疗史者。     

Priming of strong semantic relations in the left and right visual fields: a time-course investigation

Prior time-course investigations of cerebral asymmetries in word processing have sometimes reported hemisphere differences in the onset and duration of semantic priming. In the current study, very strongly related word pairs (categorical associates such as arm-leg) were employed in a low relatedness proportion lexical decision priming paradigm. A range of prime-target stimulus onset asynchronies (SOAs: 150-800 ms) was included. Only very weak evidence was obtained for a LVF priming lag at the briefest SOA, while priming was bilateral at moderately long SOAs. We consider these data in the context of previous time-course studies and suggest that, when highly semantically similar word pairs are used, a right hemisphere priming lag is, at best, a very small effect.     

Priming illusory words: an ERP approach

Repetition blindness (RB) was used to investigate whether illusory words emerge at a lexical-perceptual or a semantic-reconstructional level. Illusory words were evoked by the rapid serial visual presentation (RSVP) of two real words and a word fragment. The initial words share the same string of letters ("CREEP"-"SHEEP"), producing a free-floating word fragment ("SH"). This fragment is likely to be linked to a subsequently presented fragment ("IFT") if both combine to a meaningful word ("SHIFT"). The processing level of the illusions was probed by prime words preceding the RSVP sequence which were semantically related or unrelated to the second real word or to the illusion. Behavioural and electrophysiological correlates of the semantic priming effect were recorded in 14 subjects. Real words related to the prime were perceived more frequently, and evoked widespread N400-like effect in the event-related brain potentials (ERPs). An ERP effect of the same polarity was obtained for illusory words, however, its latency was delayed and the topographical distribution was restricted to left posterior electrode positions. These differences suggest that priming might affect real and illusory words at different levels of word processing: access to real words is facilitated at a semantic level, whereas lexical activation apparently accompanies the generation of illusory words.     

N400 during lexical decision tasks: a current source localization study

OBJECTIVE: Our primary aim in the present study was to establish the anatomic and psychophysiological correlates of automatic and controlled semantic priming. METHODS: Current sources were calculated on N400 component data from a previous study on lexical decision tasks [Clin Neurophysiol 1999;110:813] using the variable resolution electromagnetic tomography method (VARETA). In this study, two experiments were carried out, one using directly related pairs and the other one using mediated related pairs. Each experiment consisted of 3 tasks that required different levels of contribution from controlled processes. RESULTS: Average source localization images showed the brain structures involved in lexical decision tasks. The automatic component of the N400 effect was related to activation of occipitotemporal and parahippocampal gyri and anterior temporal lobes bilaterally. The expectancy strategy was related to activation of the right posterior temporal and right frontal areas. The postlexical strategy was associated with activation of right frontal, anterior cingulate and bilateral superior parietal areas. CONCLUSIONS: The findings indicated that the current sources of the N400 varied according to the relative contributions of automatic and controlled mechanisms. Moreover, the sources of the N400 effect depended on the type of strategy used.     

Implicit phonological and semantic processing in children with developmental dyslexia: Evidence from event-related potentials

Dyslexia is characterized by a core phonological deficit, although recent studies indicate that semantic impairment also contributes to this condition. In this study, event-related potentials (ERP) were used to examine whether the N400 wave in dyslexic children is modulated by phonological or semantic priming, similarly to age-matched controls. ERPs were recorded while children listened to word lists in which the semantic and phonological congruency of the terminal words were manipulated. No overt judgments were made by participants. In control children the N400 amplitude to both semantically and phonologically incongruent words was enlarged relative to congruent words. Dyslexic children exhibited a dissociation of priming effects depending on whether semantic or phonological primes were used. Semantic priming elicited an N400 effect comparable to controls, though delayed. In phonological priming, the dyslexics differed from controls in both the phonologically incongruent and congruent conditions showing reduced N400 amplitude in the former and enhanced N400 in the latter. This pattern suggests that when faced with phonological priming, dyslexics show abnormal neural responses related to both integration of similarities between the consecutive stimuli and the ability to detect incongruent stimuli. Semantic priming seems relatively intact in dyslexics, however neural responses to contextual incongruency are delayed.     

The influence of information structure on the depth of semantic processing: how focus and pitch accent determine the size of the N400 effect

To highlight relevant information in dialogues, both wh-question context and pitch accent in answers can be used, such that focused information gains more attention and is processed more elaborately. To evaluate the relative influence of context and pitch accent on the depth of semantic processing, we measured event-related potentials (ERPs) to auditorily presented wh-question-answer pairs. A semantically incongruent word in the answer occurred either in focus or in non-focus position as determined by the context, and this word was either accented or unaccented.Semantic incongruency elicited different N400 effects in different conditions. The largest N400 effect was found when the question-marked focus was accented, while the other three conditions elicited smaller N400 effects. The results suggest that context and accentuation interact. Thus accented focused words were processed more deeply compared to conditions where focus and accentuation mismatched, or when the new information had no marking. In addition, there seems to be sex differences in the depth of semantic processing. For males, a significant N400 effect was observed only when the question-marked focus was accented, reduced N400 effects were found in the other dialogues. In contrast, females produced similar N400 effects in all the conditions. These results suggest that regardless of external cues, females tend to engage in more elaborate semantic processing compared to males.     

N400 processes inhibit inappropriately activated representations: Adding a piece of evidence from a high-repetition design

The N400 event-related potential could index the activation/integration of representations corresponding to the stimulus or, on the contrary, the inhibition of representations that have been inappropriately activated. To test this alternative, series of 3 words were visually presented to subjects in a relatively rapid succession in order to prevent any disengagement of attention. In one block, participants had to judge whether the meaning of the 1st word was related to that of the 3rd. Representations activated by the 2nd word were thus inappropriate and had to be ignored. In another block, these representations were task appropriate as subjects were asked to decide whether the meaning of the 2nd word was related to that of the 3rd. The new technique of massive repetitions was used in order to obtain early peaking and short lasting N400 effects that would be easier to distinguish from effects on the contingent negative variations (CNVs) triggered by the expectancy of 3rd words. The ERPs elicited by 2nd words were more negative in the N400 time window when their meanings were task inappropriate than when these meanings had to be used. These differences were maximal at the latency of the peak of the N400 deflection rather than at the latency of the maximum of the late positive complex or at that of the CNV. They appeared to be greater at centro-parietal sites and slightly larger over the right than over the left hemiscalp. The results thus bring further support to the idea that N400 processes are of an inhibitory nature.     

46例正常成人事件相关脑电位N400实验研究

目的 取得本实验室正常成人事件相关脑电位(ERP)N 400实验方法及正常值.方法 应用中国广州润杰WJ-1型ERP仪,对46名20～54岁右利手正常成人受试者,进行汉语成语正常结尾(匹配)与成语结尾歧义词(不匹配)的研究.结果 (1)分析了N 400基本波型,正常成人N 400波形较稳定.(2)建立了Cz、Fz和Pz区域N 400指标平均值.(3)波形分析所见,不匹配结尾词的N 400较匹配的N 400潜伏期较长,波幅高.N 400分布于Fz、Cz和Pz各区.结论 正常成人N 400是可靠的,可作为有临床价值的ERP用于精神科伴有语言障碍疾病的评估.