Effects of word form on brain processing of written Chinese

Both logographic characters and alphabetic pinyins can be used to write words in Chinese. Here we use fMRI to address the question of whether the written form affects brain processing of a word. Fifteen healthy, right-handed, native Chinese-reading volunteers participated in our study and were asked to read silently either Chinese characters (8 subjects) or pinyins (7 subjects). The stimulus presentation rate was varied for both tasks to allow us to identify brain regions with word-load-dependent activation. Rate effects (fast minus slow presentations) for Chinese character reading were observed in striate and extrastriate visual cortex, superior parietal lobule, left posterior middle temporal gyrus, bilateral inferior temporal gyri, and bilateral superior frontal gyri. Rate effects for pinyin reading were observed in bilateral fusiform, lingual, and middle occipital gyri, bilateral superior parietal lobule/precuneus, left inferior parietal lobule, bilateral inferior temporal gyrus, left middle temporal gyrus, and left superior temporal gyrus. These results demonstrate that common regions of the brain are involved in reading both Chinese characters and pinyins, activated apparently independently of the surface form of the word. There also appear to be brain regions in which activation is dependent on word form. However, it is unlikely that these are entirely specific for a given word form; their activation more likely reflects relative functional specializations within broader networks for processing written language.     

出声阅读条件下不规则汉字频率效应的功能磁共振成像研究

目的利用事件相关功能磁共振成像技术观察出声阅读条件下不规则汉字频率效应的脑激活模式.方法 8名非语言专业大学生在MR扫描过程中执行汉字出声阅读任务.用视觉方式随机呈现40个形声字,其中高频、低频不规则字各20个.结果左侧额中回、左侧额下回、辅助运动区、左侧颞下回后部、双侧纹外皮层、左侧岛叶、扣带回前部表现出频率效应,即阅读低频汉字时的激活强于高频汉字.结论出声阅读汉字特别是低频不规则汉字可激活主要语言加工区,可作为可靠而实用的临床诊断试验.扣带回前部与左侧额中回可能是汉字阅读的特殊脑区.     

汉字与英文字形辨认的脑功能磁共振成像初步研究

目的:探讨功能磁共振成像(fMRI)技术研究人脑汉字与英文字形辨认方面的价值。材料与方法:12例(男5例,女7例)母语为汉语且裸眼视力正常的大学生参加实验。设备为GE Signa 1.5T MR仪,采用EPI序列,BOLD法行脑功能磁共振扫描。实验任务分别将汉字与英文(真字、假字、非字)投射到屏幕上,受试者通过头线圈反光镜观看屏幕并辨认。数据分析使用SPM 99升级软件,经过数据采集、预处理和建立模型显示结果。结果:汉字真字刺激在左额叶、中央前回(BA6)及枕叶(BA18)显著激活;左顶叶、中央后回(BA3)、右额下回(BA9)及双侧颞叶少量激活。英文真字刺激时左额中回、中央前回、左额下回显著激活;左颞梭状回(BA37)、右枕语言回(BA18)及左顶叶(BA40)也有激活。汉字和英文假字与非字只引起少量激活(P>0.05)。汉字与英文刺激左大脑半球的激活体积明显大于右半球;除枕叶外,英文在额、颞及顶叶引起的激活体积均大于汉字。结论:fMRI是研究人脑汉字和英文语言加工理想的无创性影像学方法,其脑加工优势半球均为左半球;母语为汉语者,其英文脑处理过程需更多的脑活动来参与和完成。     

阅读半规则汉字时的脑激活模式:声调的作用

目的引入声调因素,运用功能磁共振成像技术进一步研究汉字规则性效应的脑激活模式.方法13名被试在磁共振扫描过程中执行视觉方式呈现的汉字出声阅读任务,根据形声字声旁与整字间读音及声调相同与否,将刺激材料细分为同音同调字、同音异调字、异音同调字和异音异调字,每类20字.结果四种条件均激活双侧额中回、额下回、前运动区及辅助运动区、左侧顶下小叶、双侧颞上回、双侧岛叶和右侧小脑,同时还各自激活了梭状回、颞中回、左内侧额叶等区域.另外,本实验还观察到这四种条件在右侧颞上回、双侧额下回等区域激活模式的特征性变化.结论存在汉字加工的半规则效应,声调的作用不应忽略.     

Neural basis of phonological processing in second language reading: an fMRI study of Chinese regularity effect

The present study examined the neural basis of phonological processing in Chinese later acquired as a second language (L2). The regularity effect of Chinese was selected to elucidate the addressed phonological processing. We recruited a group of alphabetic language speakers who had been learning Chinese as L2 for at least one year, and a control group of native Chinese speakers. Participants from both groups exhibited a regularity effect in a pilot behavioral test. Neuroimaging results revealed that L2 learners exhibited stronger activation than native Chinese speakers in the right occipitotemporal region (i.e. right lingual gyrus and right fusiform gyrus). Moreover, L2 learners exhibited greater activations in the ventral aspects of the left inferior parietal lobule (LIPL) and the left inferior frontal gyrus (LIFG) for irregular character reading minus regular character reading. In contrast, native Chinese speakers exhibited more dorsal activations in the LIPL and LIFG. According to the "accommodation/assimilation" hypothesis of second language reading, the current findings suggest that native speakers of alphabetic languages utilized an accommodation pattern for the specific requirements of the visual form of Chinese characters, and an assimilation pattern for orthography-to-phonology transformation in Chinese reading.     

功能磁共振成像在人脑数字及汉字认知加工中的初步研究

目的应用功能磁共振成像(fMRI)对比研究人脑在数字和汉字认知刺激下脑功能活动,探讨其精确脑区定位及其可能机制。方法母语为汉语的12例右利手健康志愿者(男5例,女7例)进行了数字和汉字的看及默读实验,使用MRI仪以BOLD法采集脑部数据,用SPM99等软件后处理,获得脑功能活动图像。结果看数字和汉字均能激活双侧纹外视区、枕上回、顶叶及额下回少部分区域;默读数字和汉字额上回及额中回激活较明显;处理汉字比处理数字在额叶激活的面积更大;还发现在汉字的认知加工过程中有豆状核、丘脑及小脑的参与。结论数字及汉字的认知加工激活脑内不同区域,额叶在汉字的处理过程中起更重要作用。fMRI是研究活体人脑语言功能十分有效的方法。     

Orthographic and phonological processing of Chinese characters: an fMRI study

The present study used functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying the orthographic and phonological processing of Chinese characters. Four tasks were devised, including one homophone judgment and three physical judgments of characters, pseudo-characters, and Korean-like nonsense figures. While the left occipitotemporal region, left dorsal processing stream, and right middle frontal gyrus constitute a network for orthographic processing, the left premotor gyrus, left middle/inferior frontal gyrus, supplementary motor area (SMA), and the left temporoparietal region work in concert for phonological processing. The ventral part of the left inferior frontal cortex responds specifically to the character stimuli, suggesting a general lexical processing role for this region for linguistic material. The stronger activation of the dorsal visual stream by Chinese homophone judgment pinpoints a tight coupling between phonological representation of Chinese characters and corresponding orthographic percepts. The concomitant engagement of sets of regions for different levels of Chinese orthographic and phonological processing is consistent with the notion of distributed parallel processing.     

A meta-analysis of fMRI studies on Chinese orthographic, phonological, and semantic processing

A growing body of neuroimaging evidence has shown that Chinese character processing recruits differential activation from alphabetic languages due to its unique linguistic features. As more investigations on Chinese character processing have recently become available, we applied a meta-analytic approach to summarize previous findings and examined the neural networks for orthographic, phonological, and semantic processing of Chinese characters independently. The activation likelihood estimation (ALE) method was used to analyze eight studies in the orthographic task category, eleven in the phonological and fifteen in the semantic task categories. Converging activation among three language-processing components was found in the left middle frontal gyrus, the left superior parietal lobule and the left mid-fusiform gyrus, suggesting a common sub-network underlying the character recognition process regardless of the task nature. With increasing task demands, the left inferior parietal lobule and the right superior temporal gyrus were specialized for phonological processing, while the left middle temporal gyrus was involved in semantic processing. Functional dissociation was identified in the left inferior frontal gyrus, with the posterior dorsal part for phonological processing and the anterior ventral part for semantic processing. Moreover, bilateral involvement of the ventral occipito-temporal regions was found for both phonological and semantic processing. The results provide better understanding of the neural networks underlying Chinese orthographic, phonological, and semantic processing, and consolidate the findings of additional recruitment of the left middle frontal gyrus and the right fusiform gyrus for Chinese character processing as compared with the universal language network that has been based on alphabetic languages.     

Development of brain networks involved in spoken word processing of Mandarin Chinese

Developmental differences in phonological and orthographic processing of Chinese spoken words were examined in 9-year-olds, 11-year-olds and adults using functional magnetic resonance imaging (fMRI). Rhyming and spelling judgments were made to two-character words presented sequentially in the auditory modality. Developmental comparisons between adults and both groups of children combined showed that age-related changes in activation in visuo-orthographic regions depended on a task. There were developmental increases in the left inferior temporal gyrus and the right inferior occipital gyrus in the spelling task, suggesting more extensive visuo-orthographic processing in a task that required access to these representations. Conversely, there were developmental decreases in activation in the left fusiform gyrus and left middle occipital gyrus in the rhyming task, suggesting that the development of reading is marked by reduced involvement of orthography in a spoken language task that does not require access to these orthographic representations. Developmental decreases may arise from the existence of extensive homophony (auditory words that have multiple spellings) in Chinese. In addition, we found that 11-year-olds and adults showed similar activation in the left superior temporal gyrus across tasks, with both groups showing greater activation than 9-year-olds. This pattern suggests early development of perceptual representations of phonology. In contrast, 11-year-olds and 9-year-olds showed similar activation in the left inferior frontal gyrus across tasks, with both groups showing weaker activation than adults. This pattern suggests late development of controlled retrieval and selection of lexical representations. Altogether, this study suggests differential effects of character acquisition on development of components of the language network in Chinese as compared to previous reports on alphabetic languages.     

母语为汉语者言语障碍的语义加工及其脑区机制

学术背景:语义的加工机制是认知神经科学关注的焦点问题之一,随着研究技术手段的不断创新和多样化,使得与语义加工的相关脑区及其各脑区的神经机制逐渐清晰。但是,目前有关汉语的语义加工机制的研究力度仍然不够,对于操汉语者所持有的汉语语义加工的脑神经机制的研究有待于进一步深化。目的:通过对操汉语者言语障碍的语义加工与相关脑区功能关系的研究成果的归纳,并对其相关的大脑神经机制与语义加工网络涉及的脑的局部系统及其功能与脑空间机构进行分析,进一步明确基础神经心理学对临床诊断、治疗及康复的意义。检索策略:作者对1984年至今的相关文献进行检索,关键词为"semantic processing",并限定文献语言为英文。检索的数据库主要有中国知网(CNKI)中国期刊全文数据库1994-01/2006-05、荷兰Elsevier公司期刊数据库1984-01/2006-05和美国EBSCOhost数据库1984-01/2006-05中Academic Source Premier和MEDLINE两个子数据库,同时手工检索与之内容相关的书籍。检索到文章264篇,纳入关于语义加工与脑区功能联系的43篇,并结合有关论著进行总结,排除联系不密切的文献,对于未发表的文章仅做参考使用。文献评价:文献来源于论著、汇总分析、个例报告、研究性报告。评价人为相关领域研究人员。资料综合:汉语语义加工的相关脑区主要涉及左侧颞上回、颞中回、颞叶前部、额下回以及左额叶中部,组成额-颞工作网共同支持语义加工,其中左侧颞上回后部和颞中回与语义加工关系最密切,涉及到语义的一般存储和自动加工,颞叶前部则与不同语义的整合加工有关;额下回与控制、执行加工,短时记忆加工有关联;左额叶中部是近年来发现的与汉语语义加工关系较大的脑区部位,现有的推论是汉字特有的字形结构的加工导致的。结论:目前,研究神经语言学的脑组织和机能的方法已经多样化,可以更逼真地观察和了解临床上的多种言语障碍及其病变机制,为言语障碍的临床治疗康复提供了极大的帮助。     

汉字词语语音、语义处理相关脑区的功能磁共振研究

目的探索汉字词语处理的脑偏侧化;研究汉字词语的语音、语义处理相关脑区及小脑在汉字词语处理中的作用.方法对13例健康、右利手、母语为汉语的受试者,采用功能磁共振成像技术,模块设计的刺激模式,运用视觉呈现方法,每名受试者参加两组实验:动词产生组及假词默读组.结果动词产生组及假词默读组均显著激活左侧额下回、左侧额中回、左侧额上回、左侧顶上小叶、双侧枕叶以及双侧小脑半球,在两组中均以左侧大脑半球激活为著;Wernicke区在两组均未见激活;左侧IFG在动词产生组较假词默读组激活范围广泛;双侧扣带回、左侧颞下回、右侧额中回、左侧丘脑及右侧尾状核仅在动词产生组被激活.结论左侧大脑半球是汉字词语处理的优势半球;Broca区在汉字词语处理中既有语音又有语义处理方面的作用;双侧小脑参与汉字词语的语音处理;大脑皮层下的一些核团可能参与汉字词语的语义处理.     

Functional specialization for semantic and phonological processing in the left inferior prefrontal cortex.

Neuroimaging and neuropsychological studies have implicated left inferior prefrontal cortex (LIPC) in both semantic and phonological processing. In this study, functional magnetic resonance imaging was used to examine whether separate LIPC regions participate in each of these types of processing. Performance of a semantic decision task resulted in extensive LIPC activation compared to a perceptual control task. Phonological processing of words and pseudowords in a syllable-counting task resulted in activation of the dorsal aspect of the left inferior frontal gyrus near the inferior frontal sulcus (BA 44/45) compared to a perceptual control task, with greater activation for nonwords compared to words. In a direct comparison of semantic and phonological tasks, semantic processing preferentially activated the ventral aspect of the left inferior frontal gyrus (BA 47/45). A review of the literature demonstrated a similar distinction between left prefrontal regions involved in semantic processing and phonological/lexical processing. The results suggest that a distinct region in the left inferior frontal cortex is involved in semantic processing, whereas other regions may subserve phonological processes engaged during both semantic and phonological tasks.     

维吾尔语和汉语动词产生相关脑区的功能性磁共振成像研究

目的通过功能性磁共振成像（fMRI）观察母语为维吾尔语（简称维语）和汉语正常人执行动词产生任务时的脑激活区及其脑激活差异区,探讨语言理解和产生的神经机制,以及脑损伤后语言障碍及其康复机制。 方法以维语和汉语名词为基本实验材料,通过血氧水平依赖功能性磁共振成像（BOLD-fMRI）扫描31例维吾尔族（语组）和28例汉族（汉语组）正常志愿者执行动词产生任务时的脑激活区,采集fMRI数据,并进行组内及组间比较。 结果汉语组的主要脑激活区为左侧尾状核、左侧枕下回、左侧梭状回、双侧辅助运动区（BA8/6区）、左侧BA32区、左侧楔前叶、左侧顶上、下小叶（BA7区）、左侧角回、右侧中央前回（BA9区）、左侧三角部额下回、右侧岛盖部额下回和双侧小脑。维语组的主要脑激活区为左侧中央前回（BA9区）、左侧岛盖部额下回、左侧三角部额下回和左侧小脑。维语组和汉语组组间比较发现,汉语组在左侧尾状核体、左侧眶部额中回、右侧尾状核头和双侧扣带回前部（BA32区）有明显激活,与维语组比较,差异有统计学意义（P<0.05）;而维语组未见比汉语组更明显激活的脑区。 结论维语和汉语正常人动词产生激活脑区不完全相同;维语文字的加工处理主要集中在左侧大脑半球;汉字加工处理比维语文字加工处理需要更多右侧大脑半球的参与。     

Multilingualism: an fMRI study

To investigate the hypothesis that in multilingual speakers different languages are represented in distinct brain regions, 12 multilingual right-handed men performed a word fluency task, a picture naming task, a comprehension reading task, and their respective control tasks in three languages (Dutch, French, and English) while whole-head functional magnetic resonance imaging (fMRI) was applied. In general, all language tasks revealed predominantly overlapping regions of activation for the different languages. Cerebral activation during use of the foreign languages showed a tendency toward a more extensive recruitment of the areas activated in the native language and the activation of a greater number of regions. Word generation in the foreign languages elicited additional bilateral inferior frontal activation, including Broca's area and left middle temporal gyrus activation; in the native language, additional postcentral activation was found. Picture naming in the foreign languages recruited additional inferior-lateral and medial frontal regions predominantly on the left, and more posterior right hemispheric activation in the mother tongue. During comprehension reading there was more activation in medial posterior regions in the native language. Our results suggest that the performance of language tasks in different languages engages largely the same cerebral areas but that the brain, to perform at a comparable proficiency level, engages more neural substrates for later acquired languages. Our findings do not support the view that languages learned later in life entail more right hemispheric involvement. Finally, a consequent effect of language exposure was found for reading, where increased familiarity engages more occipital activation whereas decreased familiarity appears to be associated with increased left hemispheric inferior frontal activation.     

A combined fMRI study of typed spelling and reading

In this study we employed a novel technique to examine the neural basis of written spelling by having subjects touch-type single words on an fMRI compatible QWERTY keyboard. Additionally, in the same group of participants we determined if task-related signal changes associated with typed spelling were also co-localized with or separate from those for reading. Of particular interest were the left inferior frontal gyrus, left inferior parietal lobe as well as an area in the left occipitotemporal cortex termed the Visual Word Form Area (VWFA), each of which have been associated with both spelling and reading. Our results revealed that typed spelling was associated with a left hemisphere network of regions which included the inferior frontal gyrus, intraparietal sulcus, inferior temporal/fusiform gyrus, as well as a region in the superior/middle frontal gyrus, near Exner's area. A conjunction analysis of activation associated with spelling and reading revealed a significant overlap in the left inferior frontal gyrus and occipitotemporal cortex. Interestingly, within the occipitotemporal cortex just lateral and superior to the VWFA we identified an area that was selectively associated with spelling, as revealed by a direct comparison of the two tasks. These results demonstrate that typed spelling activates a predominantly left hemisphere network, a subset of which is functionally relevant to both spelling and reading. Further analysis revealed that the left occipitotemporal cortex contains regions with both conjoint and dissociable patterns of activation for spelling and reading.     

Dissociation of working memory processing associated with native and second languages: PET investigation

Verbal working memory plays a significant role in language comprehension and problem-solving. The prefrontal cortex has been suggested as a critical area in working memory. Given that domain-specific dissociations of working memory may exist within the prefrontal cortex, it is possible that there may also be further functional divisions within the verbal working memory processing. While differences in the areas of the brain engaged in native and second languages have been demonstrated, little is known about the dissociation of verbal working memory associated with native and second languages. We have used H2(15)O positron emission tomography in 14 normal subjects in order to identify the neural correlates selectively involved in working memory of native (Korean) and second (English) languages. All subjects were highly proficient in the native language but poorly proficient in the second language. Cognitive tasks were a two-back task for three kinds of visually presented objects: simple pictures, English words, and Korean words. The anterior portion of the right dorsolateral prefrontal cortex and the left superior temporal gyrus were activated in working memory for the native language, whereas the posterior portion of the right dorsolateral prefrontal cortex and the left inferior temporal gyrus were activated in working memory for the second language. The results suggest that the right dorsolateral prefrontal cortex and left temporal lobe may be organized into two discrete, language-related functional systems. Internal phonological processing seems to play a predominant role in working memory processing for the native language with a high proficiency, whereas visual higher order control does so for the second language with a low proficiency.     

汉语及图片语义加工机制的fMRI研究

目的利用功能磁共振成像(fMRI)技术探讨汉字及图片语义加工的脑机制。方法对13名正常青年受试者进行视觉方式呈现汉字及图片语义辨别任务的fMRI扫描,采用AFNI软件进行数据分析和脑功能区活动图像。结果fMRI显示两种任务均激活了左侧顶下小叶、额中回、额下回、右侧小脑及双侧梭状回、舌回、枕中回、枕下回、辅助运动区。其中左侧顶下小叶、额中回及双侧枕中回、梭状回在图片语义辨别任务激活明显强于汉字任务,有显著性差异(P<0.05)。结论汉字及图片语义的脑加工均存在偏侧化现象,图片语义的脑处理有更多的脑活动参与完成。     

功能磁共振观察儿童文盲与非文盲语言加工相关脑区

目的 利用事件相关功能磁共振成像技术(fMRI)对儿童文盲和非文盲汉语加工相关脑区进行探讨.方法 分别对38名儿童(19名文盲和19名非文盲)进行汉字和简单图形判断的测试,同时采集其脑部的fMRI数据.使用基于Matlab7.0的SPM2软件进行数据分析,并生成脑功能区激活图像,对组内和组间数据分别进行单样本和双样本t检验分析.结果 儿童汉字加工激活了由多个脑区构成的神经网络,与成人基本一致,其中非文盲组和文盲组的差异性脑区位于左侧额中回(BA46/9),左侧角回(BA39),左侧梭状回(BA37).结论 左侧额中回(BA46/9)、左侧角回(BA39)及左侧梭状回(BA37)与汉语语义加工密切相关,读写能力在一定程度上改变了语言加工的神经网络联结模式.     

熟练蒙汉双语者语义加工脑机制的fMRI分析

目的探讨熟练蒙汉双语者在蒙语和汉语语义信息加工的脑机制。方法对15右利手、蒙汉双语熟练的健康志愿者(男8名,女7名)进行fMRI测试,分析采用蒙语及汉语词语的语义判断任务。应用AFNI软件分析两种语言任务的脑功能激活情况及其差异。结果在汉语及蒙语语义信息加工过程中,语义加工的经典脑区均被激活,包括左侧颞中回、左侧后顶叶、左侧前额叶等区域。比较加工蒙语及汉语的语义信息过程,蒙语任务下左侧楔回及右侧梭状回的激活显著增加,汉语任务下在左侧颞中回后部、左侧额中回及额下回三角部、左侧顶上小叶的脑激活比蒙语显著增加。结论熟练蒙汉双语者在加工蒙语及汉语时,存在功能加工脑区的分离。fMRI研究能为双语者的语言加工脑机制提供影像学依据。