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。     

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.     

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。     

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。     

首发精神分裂症患者康复过程中事件相关脑电位N400随访

目的研究首发精神分裂症患者的N400变异与临床症状和康复的关系。方法对58例精神分裂症首发患者和62名健康成人作了N400检测。并用阳性和阴性症状量表(PANSS)评定患者精神症状。患者组于治疗6月、15月时进行N400随访。结果 (1)与健康成人相比,患者组服药前的N400潜伏期和波幅在Cz、Pz、Fz、C3、C45个脑区明显延迟于对照组和波幅下降。(2)N400潜伏期延迟和波幅下降与阳性症状分和PANSS总分呈负相关。(3)患者组在治疗后的6月、15月随访时,N400潜伏期和波幅有显著性差异(N400潜伏期,非匹配:治疗前446±35ms,治疗6月440±37ms,治疗15月414±31ms,F值=9.72,P<0.01。N400波幅,匹配:治疗前5.2±4.6μV,治疗6月5.7±4.8μV,治疗15月7.3±5.0μV,F值=2.06,P>0.05。非匹配:治疗前8.5±5.9μV,治疗6月10.1±5.0μV,治疗15月11.9±7.0μV,F值=3.697,P<0.05)。结论 N400对精神分裂症的疗效具有一定的预测作用。随访显示精神分裂症的语言及认识缺陷症状是渐进性过程,随着疗程或治疗发生相应变化。     

门诊及长期住院的精神分裂症患者事件相关脑电位N400对照研究

目的:比较门诊及长期住院治疗的精神分裂症患者事件相关脑电位(ERPs) N400潜伏期及波幅。方法:采用汉语成语模式,对23例门诊精神分裂症患者(门诊患者组)、27例住院精神分裂症患者(住院患者组)进行N400检测,并与25名健康成人(正常对照组)比较。结果:与正常对照组比较,两患者组同音异形异义的匹配N400潜伏期显著延迟于对照组(P均0.01);住院患者组异音形似异义匹配、异音异形同义非匹配以及异音异形异义非匹配N400潜伏期显著延迟(P 0.05或P 0.01);两患者组异音异形同义的匹配、非匹配的N400波幅明显降低(P 0.05或P 0.01);住院患者组同音异形异义匹配、同音异形异义非匹配、异音形似异义匹配的N400波幅明显降低(P 0.05或P 0.01)。与门诊患者组相比,住院患者组异音异形同义非匹配以及异音异形异义非匹配N400潜伏期显著延迟明显延迟(P 0.05或P 0.01);异音异形同义非匹配N400波幅明显降低(P 0.01)。结论:精神分裂症患者存在特异性的语言障碍;长期住院患者语言障碍更明显。     

度洛西汀对抑郁症患者认知损害的汉语句子N400的影响

目的 探讨度洛西汀对抑郁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抑郁症诊断标准的60例患者分为阿米替林治疗组(实验组1,n=30)及度洛西汀治疗组(实验组2,n=30),选择30例健康者作为对照组.实验组治疗8周前后予汉密尔顿抑郁量表(HAMD)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,实验组1HAMD评分高于实验组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 抑郁症患者存在与语言加工有关的认知损害,度洛西汀具有改善抑郁症患者认知功能的作用.     

重复经颅磁刺激对精神分裂症患者事件相关电位的影响

目的:探讨重复经颅磁刺激(rTMS)对精神分裂症患者事件相关脑电位(ERPs) N400、P300和失匹配负波(MMN)的影响。方法:给予85例精神分裂症患者(患者组)在原抗精神病药治疗的基础上联合rTMS治疗25次;于rTMS治疗前后进行N400、P300及MMN检测,结果进行自身对照及与76名健康志愿者(正常对照组)比较。结果:与正常对照组比较,患者组额区N400、P300和MMN潜伏期明显延迟、波幅明显降低(P 0.05或P 0.01);治疗后患者额区N400中同音异形异义潜伏期和异音异形异义波幅、额区MMN及P300波幅较治疗前明显提高(P均0.05)。结论:精神分裂症患者ERP指标异常,经rTMS治疗可明显改善N400、P300和MMN。     

抑郁症患者汉语情绪词阈下的Stroop效应事件相关电位

背景：抑郁症患者负性认知偏差与情绪信息加工的关系是一个重要的研究课题。情绪Stroop测验常用于评估情绪加工特点,而情绪词阈下Stroop刺激模式也常用于精神病学临床研究。 目的：本研究采用阈下汉语情绪词Stroop刺激范式来探讨抑郁症患者异常情绪信息加工的事件相关电位(ERP)效应。 设计,时间和地点：随机对照设计,时间为2007年8月至2008年3月,地点在中南大学湘雅二医院。 研究对象：首发抑郁症患者26例,符合DSM-IV抑郁症诊断标准,无脑部疾病、躯体疾病,未进行电休克治疗和抗抑郁药物治疗。健康对照组24例。两组在年龄、性别和教育水平方面无差异,均为右利手。 方法：采用阈下汉语情绪词Stroop刺激范式,要求被试对呈现200ms的红色或蓝色方块进行反应,而汉语情绪词阈下启动刺激为20ms。主要分析行为学和ERP数据。 主要测试指标：反应时和ERP成分的潜伏期和波幅。参照ERP平均波幅图以及其它研究,主要分析N270 (220~300ms)成分和N400 (380~450ms)成分的潜伏期和波幅。 结果：行为数据显示两组正确率之间无显著性差异,抑郁症组反应时比正常对照组延长,尤其是负性词与中性词(p<0.01)。重复测量方差分析表明,N270成分的波幅有词性和电极的主效应(p<0.01)以及词性和电极的交互效应(p<0.05);两组波幅大小顺序均为正性词>负性词>中性词。组别、词性差异波地形图显示差异主要分布在额区和左侧顶颞区。N400成分的波幅有词性和电极的主效应(p<0.01),潜伏期显示电极的主效应(p<0.01)以及电极和组别的交互效应(p<0.01);两组波幅大小顺序均为正性词>负性词>中性词,而且两组之间的三种情绪词波幅之间有显著性差异(p<0.01)。组别、词性差异波地形图显示差异主要分布在左右额区、中央区和左侧顶颞区。 结论：抑郁症患者执行阈下汉语情绪词Stroop刺激作业时表现了异常的情绪信息加工特征,以及对汉语情绪词三种词性进行语义激活时与正常组相比表现为不同的ERP时程效应。研究结果支持我们提出的正负性情绪平行神经模型。     

The lateral distribution of event-related potentials during sentence processing

Event-related brain potentials (ERPs) were recorded from adults as they read 160 different sentences, half of which ended with a semantically anomalous word. These deviant words elicited a broad, negative component (N400). Measured in the difference wave between ERPs to incongruous and congruous endings, the N400 was slightly larger and more prolonged over the right than the left hemisphere and diminished in amplitude over the course of the experiment. A left-greater-than-right asymmetry was again observed in the slow, positive ERP elicited by the first six words in the sentences, being most pronounced for subjects having no left-handers in their immediate family.     

Event-related potential correlates of negation in a sentence-picture verification paradigm

In a sentence-picture verification paradigm, participants were presented in a rapid-serial-visual-presentation paradigm with affirmative or negative sentences (e.g., "In the front of the tower there is a/no ghost") followed by a matching or mismatching picture. Response latencies and event-related potentials (ERPs) were measured during reading and verification. An enhanced negative shift in the ERPs for the subject noun (i.e., "ghost") in negative, compared to affirmative sentences, was found during reading. We relate this ERP deflection to enhanced processing demands required by the negative particle no. Although this effect suggests a direct impact of negation on language processing, results for picture processing reveal that negation is not immediately integrated into sentence meaning. When the delay of picture presentation was short (250 msec), verification latencies and ERPs evoked by the picture showed a priming effect independent of whether the sentence contained a negation. Unprimed pictures (foreground object not mentioned in the sentence) led to longer latencies and higher N400 amplitudes than primed pictures (foreground object mentioned in the sentence). Main effects of negation showed up only in a late positive-going ERP effect. In contrast, when the delay was long (1500 msec), we observed main effects of truth value and negation in addition to the priming effect already in the N400 time window, that is, negation is fully integrated into sentence meaning only at a later point in the comprehension process. When negation has not yet been integrated, verification decisions appear to be modulated by additional time-consuming reanalysis processes.     

Grammatical processing without semantics? An event-related brain potential study of preschoolers using jabberwocky sentences

Behavioral studies have demonstrated that children develop a nearly adult-like grammar between 36 and 42 months, but few studies have addressed how the child's brain processes semantic versus syntactic information. In previous research, Silva-Pereyra and colleagues showed that distinct event-related potentials (ERPs) are elicited by semantic and syntactic violations in sentences in children as young as 30, 36, and 48 months, following the patterns displayed by adults. In the current study, we examined ERPs to syntactic phrase structure violations in real and jabberwocky sentences in 36-month-old children. Jabberwocky sentences are sentences in which content (open-class) words are replaced by pseudowords while function (closed-class) words are retained. Results showed that syntactically anomalous real sentences elicited two positive ERP effects: left-distributed effects from 500 to 750 msec and 1050 to 1300 msec, whereas syntactically anomalous jabberwocky sentences elicited two negative ERP effects: a left-distributed effect from 750 to 900 msec and a later broadly distributed effect from 950 to 1150 msec. The results indicate that when preschoolers process real English sentences, ERPs resembling the positive effects previously reported for adults are noted, although at longer latencies and with broader scalp distributions. However, when preschoolers process jabberwocky sentences with altered lexical-semantic content, a negative-going ERP component similar to one typically associated with the extraction of meaning is noted.     

Picture the difference: electrophysiological investigations of picture processing in the two cerebral hemispheres

The nature of semantic memory and the role of the two cerebral hemispheres in meaning processing were examined using event-related brain potentials (ERPs) elicited by pictures in sentences. Participants read sentence pairs ending with the lateralized presentation of three target types: (1) expected pictures, (2) unexpected pictures from the expected semantic category, and (3) unexpected pictures from an unexpected category. ERPs to contextually unexpected pictures were more negative 350-500ms (larger N400s) than those to expected pictures in both visual fields. However, while N400s to the two types of unexpected items did not differ with left visual field presentations, they were smaller to the unexpected items from the expected category with right visual field presentations. This pattern, previously observed to words [Brain Language 62 (1998) 149], suggests general differences in how the two hemispheres use context on-line. Other aspects of the N400 response-and effects on earlier ERP components-reveal differences between pictures and words, suggesting that semantic memory access is not modality-independent. The P2 component varied with ending type for right but not left visual field presentations, suggesting that the left hemisphere may use contextual information to prepare for the visual analysis of upcoming stimuli. Furthermore, there was clear evidence for an earlier negativity ("N300"), which varied with ending type but, unlike the N400, was unaffected by visual field of presentation. Overall, the results support our hypothesis that the left hemisphere actively uses top-down information to preactivate perceptual and semantic features of upcoming stimuli, while the right hemisphere adopts a "wait and see" integrative approach.     

The influence of language proficiency on lexical semantic processing in native and late learners of English

We investigated the influence of English proficiency on ERPs elicited by lexical semantic violations in English sentences, in both native English speakers and native Spanish speakers who learned English in adulthood. All participants were administered a standardized test of English proficiency, and data were analyzed using linear mixed effects (LME) modeling. Relative to native learners, late learners showed reduced amplitude and delayed onset of the N400 component associated with reading semantic violations. As well, after the N400 late learners showed reduced anterior negative scalp potentials and increased posterior potentials. In both native and late learners, N400 amplitudes to semantically appropriate words were larger for people with lower English proficiency. N400 amplitudes to semantic violations, however, were not influenced by proficiency. Although both N400 onset latency and the late ERP effects differed between L1 and L2 learners, neither correlated with proficiency. Different approaches to dealing with the high degree of correlation between proficiency and native/late learner group status are discussed in the context of LME modeling. The results thus indicate that proficiency can modulate ERP effects in both L1 and L2 learners, and for some measures (in this case, N400 amplitude), L1-L2 differences may be entirely accounted for by proficiency. On the other hand, not all effects of L2 learning can be attributed to proficiency. Rather, the differences in N400 onset and the post-N400 violation effects appear to reflect fundamental differences in L1-L2 processing.     

Differences in the late components of the event-related potential due to age and to semantic and non-semantic tasks

Recent work in event-related potentials (ERPs) has revealed differences between ERPs elicited during the performance of semantic and nonsemantic tasks. This experiment examined age differences in the late components of the ERP as a function of these tasks. Young and elderly males were presented with 5-word strings on each trial. The subject's task was to decide whether or not the fifth word matched the other four. In one condition, the first 4 words were identical to one another and the fifth word was either the same or different. In the other condition, the first 4 words were different from one another but were drawn from from the same semantic category. The fifth word was either from the category or from a different category. Matches occurred in 15% of the trials and mismatches in 85%. The ERP to the fifth word was analyzed. All ERPs evidenced a late positive component (LPC), the latency of which was greater for the Category task and for mismatches. LPC amplitude was greater in the Identity task. In addition, young subjects' LPC amplitudes were greater for matches than for mismatches, whereas the reverse was true for the elderly. In agreement with previous research, our results indicated that an N400 wave is evident only in response to semantic incongruity and that variables affecting late positive activity seem to be independent of those producing N400. The N400 wave was seen at a greater latency in the elderly. Our results extend previous work (e.g., Kutas and Hillyard 1980) by finding an N400 in a semantic context other than sentences, and in concluding that this component is relatively insensitive to stimulus frequency.     

What's left if the Jabberwock gets the semantics? An ERP investigation into semantic and syntactic processes during auditory sentence comprehension

This study examined auditory ERP responses to syntactic phrase structure violations occurring either in sentences containing regular words or in sentences in which content words had been replaced by pseudowords while retaining morphological markers (so-called jabberwocky sentences). Syntactic violations were found to elicit an early anterior negativity followed by a P600 for both types of sentences, suggesting that the syntactic processes in question are independent of the presence of lexical-semantic information. In syntactically correct sentences, content words in regular sentences elicited an N400 component while their pseudoword place-holders in jabberwocky sentences did not. By contrast, in syntactically incorrect sentences neither sentence type showed an N400 for the word creating the syntactic violation, indicating that the detection of a syntactic error at an early stage blocks semantic integration processes in regular sentences. We discuss these results and findings from related studies in the light of a timing hypothesis of syntactic and semantic information processing and propose that syntactic information extracted particularly early can affect semantic processes while syntactic information extracted relatively late cannot.     

Finding needles in haystacks: symbolic resonance analysis of event-related potentials unveils different processing demands

Previous ERP studies have found an N400-P600 pattern in sentences in which the number of arguments does not match the number of arguments that the verb can take. In the present study, we elaborate on this question by investigating whether the case of the mismatching object argument in German (accusative/direct object versus dative/indirect object) affects processing differently. In general, both types of mismatches elicited a biphasic N400-P600 response in the ERP. However, traditional voltage average analysis was unable to reveal differences between the two mismatching conditions, that is, between a mismatching accusative versus dative. Therefore, we employed a recently developed method on ERP data analysis, the symbolic resonance analysis (SRA), where EEG epochs are symbolically encoded in sequences of three symbols depending on a given parameter, the encoding threshold. We found a larger proportion of threshold crossing events with negative polarity in the N400 time window for a mismatching dative argument compared to a mismatching accusative argument. By contrast, the proportion of threshold crossing events with positive polarity was smaller for dative in the P600 time window. We argue that this difference is due to the phenomenon of "free dative" in German. This result also shows that the SRA provides a useful tool for revealing ERP differences that cannot be discovered using the traditional voltage average analysis.