Correlation between topographic N400 anomalies and reduced cerebral blood flow in the anterior temporal lobes of patients with dementia

In Alzheimer's disease (AD) patients, episodic memory impairments are apparent, yet semantic memory difficulties are also observed. While the episodic pathology has been thoroughly studied, the neurophysiological mechanisms of the semantic impairments remain obscure. Semantic dementia (SD) is characterized by isolated semantic memory deficits. The present study aimed to find an early marker of mild AD and SD by employing a semantic priming paradigm during electroencephalogram recordings. Event-related potentials (ERP) of early (P1, N1) and late (N400) word processing stages were obtained to measure semantic memory functions. Separately, baseline cerebral blood flow (CBF) was acquired with arterial spin labeling. Thus, the analysis focused on linear regressions of CBF with ERP topographical similarity indices in order to find the brain structures that showed altered baseline functionality associated with deviant ERPs. All participant groups showed semantic priming in their reaction times. Furthermore, decreased CBF in the temporal lobes was associated with abnormal N400 topography. No significant CBF clusters were found for the early ERPs. Taken together, the neurophysiological results suggested that the automatic spread of activation during semantic word processing was preserved in mild dementia, while controlled access to the words was impaired. These findings suggested that N400-topography alterations might be a potential marker for the detection of early dementia. Such a marker could be beneficial for differential diagnosis due to its low cost and non-invasive application as well as its relationship with semantic memory dysfunctions that are closely associated to the cortical deterioration in regions crucial for semantic word processing.

Tarkkaavaisuuden vaikutus puheen merkityssisällön käsittelyyn: Aivojen herätevastetutkimus

Semantic processing can be studied with semantic priming. Target words that are preceded by semantically related prime words are recognized faster and more accurately than targets preceded by unrelated prime words. Semantic priming also affects the magnitude of the N400 event-related potential. The response is smaller to a target word when it is preceded by a related than an unrelated prime word. The effect is called the N400 effect. It is not yet clear, however, how attention modulates semantic priming and the N400 effect. This study investigated how the direction of attention affects the semantic processing of speech. The N400 effect was studied in experimental conditions in which the subjects attention was directed 1) away from the speech stimuli, 2) to phonological features of the speech stimuli, and 3) to semantic features of the speech stimuli. The first aim of the study was to investigate whether the N400 effect for spoken words is dependent on attention to the auditory information. The second aim was to study the differences in the N400 effect when attention is directed to the semantic or other features of speech stimuli. The results showed an N400 effect even when attention was directed away from the speech stimuli. The N400 effect was, however, stronger in conditions during which the speech stimuli were attended. The magnitude of the behavioral semantic priming and the N400 effect did not differ between the conditions during which attention was directed to the semantic or phonological features of the words. The findings indicate that the semantic processing of spoken words is not dependent on attention to auditory information. Furthermore, the results suggest that whether or not semantic processing is relevant for the task performance does not affect the semantic processing of attended spoken words.

Integrated semantic processing of complex pictures and spoken sentences - Evidence from event-related potentials

It has been suggested that semantic information processing is modularized according to the input form (e.g., visual, verbal, non-verbal sound). A great deal of research has concentrated on detecting a separate verbal module. Also, it has traditionally been assumed in linguistics that the meaning of a single clause is computed before integration to a wider context. Recent research has called these views into question. The present study explored whether it is reasonable to assume separate verbal and nonverbal semantic systems in the light of the evidence from event-related potentials (ERPs). The study also provided information on whether the context influences processing of a single clause before the local meaning is computed. The focus was on an ERP called N400. Its amplitude is assumed to reflect the effort required to integrate an item to the preceding context. For instance, if a word is anomalous in its context, it will elicit a larger N400. N400 has been observed in experiments using both verbal and nonverbal stimuli. Contents of a single sentence were not hypothesized to influence the N400 amplitude. Only the combined contents of the sentence and the picture were hypothesized to influence the N400. The subjects (n = 17) viewed pictures on a computer screen while hearing sentences through headphones. Their task was to judge the congruency of the picture and the sentence. There were four conditions: 1) the picture and the sentence were congruent and sensible, 2) the sentence and the picture were congruent, but the sentence ended anomalously, 3) the picture and the sentence were incongruent but sensible, 4) the picture and the sentence were incongruent and anomalous. Stimuli from the four conditions were presented in a semi-randomized sequence. Their electroencephalography was simultaneously recorded. ERPs were computed for the four conditions. The amplitude of the N400 effect was largest in the incongruent sentence-picture -pairs. The anomalously ending sentences did not elicit a larger N400 than the sensible sentences. The results suggest that there is no separate verbal semantic system, and that the meaning of a single clause is not processed independent of the context.

Neurocognitive processing of inflected and derived words

The representation of morphologically complex words in the mental lexicon and their neurocognitive processing has been a vigorously debated topic in psycholinguistics and the cognitive neuroscience of language. This thesis investigates the effect of stimulus modality on morphological processing, the spatiotemporal dynamics of the neural processing of inflected (e.g., work+ed ) and derived (e.g., work+er ) words and their interaction, using the Finnish language. Overall, the results suggest that the constituent morphemes of isolated written and spoken inflected words are accessed separately, whereas spoken derived words activate both their full form and the constituent morphemes. The processing of both spoken and written inflected words elicited larger N400 responses than monomorphemic words (Study I), whereas the responses to spoken derived words did not differ from those to monomorphemic words (Study IV). Spoken inflected words elicited a larger left-lateralized negativity and greater source strengths in the left temporal cortices than derived words (Study IV). Thus, the results suggest different cortical processing for derived and inflected words. Moreover, the neural mechanisms underlying inflection and derivation seem to be not only different, but also independent as indexed by the linear summation of the responses to derived and inflected stimuli in a combined (derivation+inflection) condition (Study III). Furthermore, the processing of meaningless, spoken derived pseudowords was more difficult than for existing derived words, indexed by a larger N400-type effect for the pseudowords. However, no differences were observed between meaningful derived pseudowords and existing derived words (Study II). The results of Study II suggest that semantic compatibility between morphemes seems to have a crucial role in a successful morphological analysis. As a methodological note, time-locking the auditory event-related potentials/fields (ERP/ERF) to the suffix onset revealed the processes related to morphological analysis more precisely (Studies II and IV), which also enables comparison of the neural processes in different modalities (Study I).

Neurolinguistic measure of typological effects in multilingual transfer: introducing an ERP methodology

This article has two main objectives. First, we offer an introduction to the subfield of generative third language (L3) acquisition. Concerned primarily with modeling initial stages transfer of morphosyntax, one goal of this program is to show how initial stages L3 data make significant contributions toward a better understanding of how the mind represents language and how (cognitive) economy constrains acquisition processes more generally. Our second objective is to argue for and demonstrate how this subfield will benefit from a neuro/psycholinguistic methodological approach, such as event-related potential experiments, to complement the claims currently made on the basis of exclusively behavioral experiments. Palabras clave

南海北部区域表层水微生物多样性及其分布特点研究

海洋中的微生物多样性是十分丰富的。南海北部区域表层水的微生物群落结构及物种多样性情况仍不十分清楚。本研究，采用构建基因克隆文库的方法，对该区域内表层水中的微生物多样性及分布特点进行研究。获得了8000多个细菌16S rDNA基因、真核微生物ITS 区基因及光合微型生物 psbA 基因单克隆。本研究结果表明：在南海北部区域表层水中存在两种不同微生物类群，即近海岸带海洋微生物类群和开阔海域海洋微生物类群。 16S rDNA基因克隆文库中，确定了507个OTUs。93.7% 的16S rDNA 序列定义在同一种水平上，1.4 %的16S rDNA序列定义在同一属的水平上，2.7%的16S rDNA序列定义在同一纲的水平上，1.2%的16S rDNA序列定义在同一门的水平上。值得一提的是有0.7%的南海表层水样品的16S rDNA 序列，属于目前数据库中的未知序列。系统育树分析表明这类序列可归属于4个不同的分枝群。与Venter’s Sorcerer II 海洋科考（马尾岛海域）的结果不同，南海北部区域表层水中，并没有发现SAR11分支细菌、丝状杆菌（Fibrobacter）和Rheinheimera细菌序列，但南海北部区域却发现了马尾岛海域未检测到的物种，如酸杆菌门、恐球菌-栖热菌门、厚壁菌门，硝化螺旋菌门，浮霉菌门以及疣微菌类细菌。除疣微菌外，其他5种细菌都是海洋环境样品中较为常见的细菌。变形菌门、蓝细菌及厚壁菌门细菌序列是南海北部表层样品16S rDNA基因克隆文库中的主要类群。 真核生物如浮游植物和海洋真菌是海洋表面生物质的主要组成部分之一。现有的研究多集中在环境样品的原核微生物的群落结构研究上，很少关注海洋微型真核生物的多样性及群落结构分布。本研究通过构建ITS基因克隆文库的方法，得到了3044条ITS序列，最终定义了1288个OTUs。其中，329个OTUs序列定义在同一种水平上，310个OTUs序列定义在同一属或纲的水平上，123个OTUs序列定义在同一门的水平上。值得注意的是有339个OTUs的序列，属于目前数据库中的未知序列。系统发育树分析表明它们分别归属于4个不同的分枝群。这表明以往对海洋真核微型生物的多样性仍知之甚少。盘菌亚门、体腔动物门和担子菌纲是南海北部表层样品ITS基因克隆文库中的主要类群。此外，在南海北部区域还发现了少数归属于绿藻、链形植物、定鞭金藻类、放射虫类、Stramenopiles、Typhlocoela、壶菌类、多孢囊霉目、子囊菌门、地位未定的物种、 酵母、领鞭毛虫门、不可培养的后生动物和海绵动物的ITS序列。 海洋初级生产力主要是依靠光合微型浮游生物进行光合作用完成的。利用新设计的psbA通用引物，对南海北部33个表层水样滤膜进行基因克隆文库建库分析，最终获得了南海北部区域表层水微生物多样性及其分布特点研究3062条部分psbA基因序列，并将其划分为957个 OTUs。其中蓝细菌和未培养的病毒序列在psbA基因库中的数量最多。本研究还发现了南海北部区域存在11个独立分支的新型psbA类群。研究证实psbA基因可以作为一种研究海洋光合微型浮游生物群落结构的指示基因。 克隆文库相似性分析发现，在所有的16S rDNA克隆文库中没有任意两个站点的克隆文库相似性超过50%。虽然N401和N420站点的16S rDNA克隆文库相似性最大，但它们在地理位置上并不接近。一些地理位置接近的站点，其16S rDNA克隆文库之间相似性比较接近。比如，海南岛区域的克隆文库之间就比较相似，且在同一分支。大多数地理环境相似的站点的16S rDNA克隆文库都聚在同一大分支上。例如，来自于珠江口区域站点的克隆文库之间的相似性比较接近，而且分布在一个大分支中；开阔海洋区域的16S rDNA克隆文库，也大多聚类在同一分支中。但也有例外的情况：比如 N107 和N400 站点的16S rDNA克隆文库，就聚类到一起，分析发现这两个文库中所处的环境都是甲烷产生区，其中都含有相似的与甲烷代谢相关的菌群。不过从整体来看，整个南海北部的细菌群落，大致分为两大类：中国大陆近海岸微生物群落和开阔海域微生物群落。33个ITS克隆文库的相似性分析发现：相似性在10%以下的类群，可以分成两大分支，而且该分类，比细菌群落的分布情况更接近南海北部的地理环境特征。对psbA基因克隆文库的相似性分析也验证了在南海北部区域表层水中存在两种不同微生物生态系统。 此外，本研究针对分子生态专业软件DOTUR程序在处理大量克隆文库数据时所遇到的

社会冲突信息加工的事件相关电位研究

Processing of discrepant information is an important part in our everyday life. According to the social attributes of information, it can be categorized into two parts: social discrepancy and nonsocial discrepant information. The researches focused on nonsocial discrepancy are much mature than those of social discrepancy processing. This serial study employed three ERP experiments to explore the attributes of social discrepancy cognition. Experiment one compared the ERP differences between social and nonsocial discrepancy processing, experiment two adopted single stimulus paradigm to explore the negativity attention biases of social emotions, experiment three investigated the affective mechanism of emotions to social discrepancy information with cue-target paradigm, based on the experiment one and two. We invited healthy undergraduates to participate in our researches, in which social gender words and affective images were stimuli to explore the temporal sequences, activated modes and affective mechanisms of social discrepancy. The results were as below: 1. The differences of attention resource distributions between social and nonsocial information processing exhibited as early as 200 ms, since which P2 was evoked in both blocks. The larger P2 in nonsocial block represented the more attention to physical and nonsocial attributes of objects. N300/400 indicated the differences of evaluating systems in each block. The cognitive mechanisms of social and nonsocial tasks were specific, based on the fact: (1) the discrepancy evaluating system was activated earlier in nonsocial block than that of social block; (2) the social cognition performed right hemisphere advantage, but nonsocial task did not so. 2. Social emotions also could raise a negativity bias on attention. The latency of P2 evoked by social sad images was shorter than that of social happiness and neutral images. The latencies of P2 indicated that sad emotions attracted attention earlier, and possessed a processing advantage. The phenomenon that the larger N2 was evoked by social sadness showed that people was easily moved by sad emotions and sympathized the sadness. 3. Emotions affected social discrepancy processing. Positive affective mood magnified the discrepancy effect, based on the smaller latencies of difference N400 and larger amplitudes. Persons with happy mood synthesized social stereotypes to accelerate the social tasks. 4. Three experiments all showed the right hemisphere advantages of social cognition and social emotions, offered more proof in laterality hypothesis of social cognition. Above all, social cognition had essential distinctions with nonsocial cognition; they two had their own specific characteristics. The fact that social cognition was prone to be affected by different emotional mood made it more complex.

农民工群体偏爱的研究

The present paper studies the explicit, implicit and the neural mechanism of group bias on rural residents, off-farm workers and urban citizens in Off-farm workers. The relations between group-bias and these factors such as collective self-esteem, self-esteem, group identity and depression were also discussed. The main results of this paper can be summarized as follows： 1. There were dissociations between explicit and implicit group-bias of the Off-farm workers on all three groups. Off-farm workers favored urban citizens implicitly most, and the bias on rural residents was least;. However, the rural residents was the group they liked most, but the urban citizens was the least. 2. The more the implicit and the less the explicit in-group bias they had, the more they felt depressive. 3. Collecitve self-esteem was only related to the explicit in-group bias. 4. The undergraduates showed bias on urban citizens and prejudice to rural residents as Off-farm workers, but their attitude towards Off-farm worker was more positive than Off-farm worker themselves was. 5.The implicit group-bias occurs rapidly and automatically which includes two potential processes as activation and inhibition and it isn’t necessary for them coexist in the same object. Besides, N400 and LPC are sensitive to the two processes respectively.

Brain-Based Individual Difference Measures of Reading Skill in Deaf and Hearing Adults

Thesis (Ph.D.)--University of Washington, 2015

Le Rappel / directeur gérant : Albert Barbieux

1870/06/22 (N400).

Revue apologétique : doctrine et faits religieux

1923/01/01 (A18,T35,N400).

L'Athlétisme : organe officiel de la Fédération française d'athlétisme

1997/05 (N400).

Bulletin de la médecine et de la pharmacie militaires

1892/11 (A41,N400).

Patriote algérien

1890/03/26 (A5,N400).