Developmental changes in the neural correlates of semantic processing

Functional magnetic resonance imaging (fMRI) was used to explore the neural correlates of semantic judgments in the auditory modality in a group of 9- to 15-year-old children. Subjects were required to indicate if word pairs were related in meaning. Consistent with previous findings in adults, children showed activation in bilateral superior temporal gyri (BA 22) for recognizing spoken words as well as activations in bilateral inferior frontal gyri (BAs 47, 45) and left middle temporal gyrus (BA 21) for semantic processing. The neural substrates of semantic association and age differences were also investigated. Words with strong semantic association elicited significantly greater activation in the left inferior parietal lobule (BA 40), whereas words with weak semantic association elicited activation in left inferior frontal gyrus (BAs 47/45). Correlations with age were observed in the left middle temporal gyrus (BA 21) and the right inferior frontal gyrus (BA 47). The pattern of results for semantic association implies that the left inferior parietal lobule effectively integrates highly related semantic features and the left inferior frontal gyrus becomes more active for words that require a greater search for semantic associations. The developmental results suggest that older children recruit the right inferior frontal gyrus as they conduct a broader semantic search and the left middle temporal gyrus to provide more efficient access to semantic representations.     

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.     

静息态脑功能技术对平衡针治疗中枢机制的分析应用

背景：平衡针治疗疾病疗效显著,但缺乏相关现代科学理论机制。目的：利用静息态脑功能成像技术探讨平衡针疗法的中枢作用机制。方法：纳入10例腰椎间盘突出腰腿痛患者及10例正常受试者,于平衡针针刺前后进行功能磁共振扫描,通过AFNI软件对与双侧杏仁核表现为显著联系的脑区进行功能连接分析,并对平衡针刺后腰椎间盘突出患者及正常受试者的脑功能连接的差异进行探讨。结果与结论：经平衡针治疗后10例腰椎间盘突出患者疼痛均有好转。脑功能连接分析显示腰椎间盘突出患者丘脑、脑干、腹前核、腹外侧核、额内侧回、额上回、额叶眶上回、额下回、颞上回、颞中回、海马回、扣带回、岛叶等脑区功能连接增强。正常受试者双侧颞中回、双侧眶上回、双侧尾状核头、双侧岛叶、左侧腹背侧核、双侧额上回、左侧额中回、前扣带回、右侧顶下小叶与杏仁核连接增强;双侧小脑齿状核、小脑蚓、左侧小脑坡、双侧舌回、左侧枕中回、右侧额上回、右侧中央前回、双侧顶下小叶、右侧顶上小叶、右侧中央后回与杏仁核连接下降。提示通过静息脑功能成像技术对杏仁核的研究有助于更深入理解平衡针灸治疗腰腿痛的中枢机制。     

Frequency effects of Chinese character processing in the brain: an event-related fMRI study

Knowing how the brain processes Chinese characters of different frequencies of occurrence may shed light on the extent to which orthographic variations of different languages can influence reading processes in the brain. In the present study, event-related fMRI was used to investigate frequency effects on Chinese character processing. Reading low-frequency characters invoked higher activation in several brain regions including the left premotor/inferior frontal gyrus, supplementary motor area, left anterior insula, left posterior inferior temporal gyrus, left superior parietal cortex, and lingual cortex, while reading high-frequency characters resulted in higher activation in the left supramarginal/angular gyrus and left precuneus. The activation pattern of reading infrequently encountered characters reflects a more demanding processing procedure of retrieving, formulating, and coordinating the phonological output. Access to the lexical route may benefit the reading of high-frequency characters. By uncovering the differential brain responses in reading Chinese characters of different occurrence frequencies, not only has a substantial overlap between functional neuroanatomy of reading Chinese and alphabetical languages been demonstrated, but also features permitting the separation of language-specific content from universal mechanisms.     

Structural connectivity influences brain activation during PVSAT in Multiple Sclerosis

To assess the influence of white matter pathology on cortical reorganization, we probed the fronto-parietal attention network in Multiple Sclerosis (MS) patients by combining the Paced Visual Serial Addition Test (PVSAT) with fMRI-guided fiber tractography (FT). During the PVSAT, the control subjects activated the left inferior parietal lobule, superior temporal gyrus, precuneus, precentral gyrus, and medial and middle frontal gyri; while the precuneus and the inferior parietal lobule gyrus bilaterally, the left precentral and angular gyri and the right superior parietal lobule were activated in the MS group. At fMRI-guided FT, the superior longitudinal fasciculus (SLF) was the main white matter tract connecting areas active during the PVSAT. We then identified two subgroups of MS patients according to the SLF mean Fractional Anisotropy, used as indicator of integrity. The activations of the MS patients with a less damaged tract were in the left hemisphere, similarly to controls; while the patients with a more damaged SLF showed bilateral cortical activations. The MS subgroups, however, did not differ in PVSAT performance. This approach could be useful to investigate the relationship between brain structural and functional plastic changes and to identify different MRI endophenotypes related to the same level of cognitive impairment.     

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。     

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.     

无灶性癫痫静息态功能MRI的功能连接研究

目的应用静息态功能MRI(rs-f MRI)功能连接方法(FC)研究无灶性癫痫(NLE)的脑功能改变,探论FC对NLE的应用价值。加深对NLE病理生理机制的理解,为其诊断及治疗提供可靠的理论依据。材料与方法对43例NLE患者和46例性别、年龄、教育程度及利手相匹配的健康志愿者(对照组),采用3.0 T超导MR扫描仪进行静息态功能序列扫描,然后将病例组与对照组分别进行FC分析,再对ALFF分析结果进行两样本t检验分析,并分析FC统计脑图与病程的相关性。结果与正常对照组相比,病例组右侧海马FC增加的脑区位于右颞上回、左颞下回、双颞中回、双前额内侧回,右额中回;左侧海马FC增加的脑区位于双颞上回、左海马旁回、左额叶、右前额内侧回、左顶下小叶、右中央后回。右侧海马FC降低的脑区位于左内囊膝、左顶下小叶、右扣带回、左额上回、左额叶;左侧海马降低的脑区位于右小脑后叶、左小脑前叶、右颞上回、右丘脑。病例组右侧海马FC病程正相关的脑区位于:左额下回、左颞下回、左颞上回、右额叶、右楔前叶、右顶叶、右顶下小叶、右额中回;左侧海马FC与病程正相关的脑区位于左舌回、双额中回、左顶下小叶、右中央后回。病例组右侧海马FC与病程呈负相关的脑区位于左小脑前叶、左内囊膝;病例组左侧海马FC与病程负相关的脑区位于左小脑扁桃体、左额上回、右颞上回、左楔前叶。结论 ALFF和FC方法可作为一种无创的脑功能研究方法,能检测出NLE静息态脑功能变化,了解与临床变量(病程)的相关性,为癫痫的病理生理机制研究提供可靠的理论依据。     

静息态功能MRI观察脑梗死后失语症患者功能连接变化

目的 采用静息态功能MRI（rs-fMRI）观察脑梗死后失语患者各脑区功能连接（FC）变化。方法 对10例脑梗死后失语症患者（观察组）及10名健康志愿者（对照组）采集rs-fMRI,以左侧额下回（LIFG）布罗卡（Broca）区为种子点,分析组内和组间ROI与其他脑区FC相关性的差异。结果 对照组双侧枕叶、顶叶、额叶、颞叶、小脑半球、小脑扁桃体及脑干与ROI FC呈正相关（P均<0.05）;观察组双侧额下回,左侧中央后回、中央前回、额中回、扣带回、豆状核、海马、楔叶、枕叶,右侧顶下小叶、缘上回与ROI的FC呈正相关（P均<0.05）;观察组双侧缘上回、颞下回、梭状回、顶下小叶、枕中回,右侧额中回、扣带回、小脑半球,左侧颞中回、颞上回等与ROI的FC的相关性高于对照组（P均<0.05）。结论 静息态下健康人脑内存在语言功能网络;左侧脑梗死后失语症患者多个脑区与LIFG Broca区的FC呈正相关,以左侧大脑半球额叶为主,可能与脑梗死后失语症的发生及恢复机制有关。     

三维动脉自旋标记技术评价阿尔茨海默病患者脑血流灌注

目的 探讨全脑3D伪连续动脉自旋标记技术（3D pcASL）对显示阿尔茨海默病（AD）患者的脑血流灌注（CBF）特点,并分析其与认知功能评分的相关性。方法 16例AD患者和19例年龄匹配的认知功能正常的对照组进行磁共振常规检查和3D ASL灌注成像检查。使用SPM8软件对获得的脑血流图进行预处理,比较两组的CBF差异;并比较CBF减低脑区的平均CBF值与MMSE、MoCA评分的相关性。结果 AD组存在CBF灌注减低区,主要为双侧颞上回、颞中回、颞下回、双侧楔前叶、双侧中扣带回、后扣带回、左侧角回、左侧顶下回及左侧额上回（t=5.32,P<0.001）。双侧楔前叶、双侧中后扣带回、双侧颞上回、左侧颞中回、左侧颞下回、左侧角回及左侧顶下回的CBF值与MMSE、MoCA评分呈正相关。结论 3D pcASL可发现AD患者脑区的灌注异常,并且 CBF减低区的CBF值与认知功能的减低存在相关性。     

ICA与SPM方法检测脑激活区的对照研究

目的：以SPM方法为参照,评估ICA方法检测激活脑区的可行性。方法：对28例（男15例,女13例）健康被试者行fMRI,实验内容为组块设计的词语联想任务,分别采用SPM5和GroupICATv2.0a软件进行数据处理和统计分析,并比较SPM方法与ICA方法处理结果的异同。结果：SPM方法检测到的激活脑区：左侧额下回、左侧岛叶、右侧额下回与右岛叶、辅助运动区、右侧小脑半球、双侧纹状体;ICA方法检测到的激活脑区：前扣带回与辅助运动区、左侧岛叶、左侧额中回与额下回、左侧顶上小叶、右侧岛叶、右侧额下回、右侧额中回、右侧小脑半球。结论：ICA方法与SPM方法检测到的激活脑区有一定差异,ICA方法可做为SPM方法的重要补充。     

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。     

Differential components of sentence comprehension: beyond single word reading and memory

A number of studies have used functional neuroimaging to examine the neural mechanisms of sentence comprehension; however, few fMRI studies have examined activation patterns associated with sentence comprehension after accounting for activation attributable to single-word-level tasks important for sentence comprehension. To investigate the patterns of activation associated with sentence comprehension after controlling for single word reading and maintaining single words in memory, 20 unimpaired adult readers completed a block design paradigm which included sentence comprehension, single word reading, and short-term memory (for words) tasks. Results indicated that, regardless of the aspect of sentence comprehension being controlled for, activation was observed in bilateral temporal lobes (left > right) as well as bilateral occipital lobes and middle frontal gyri. Additional findings showed that bilateral superior parietal lobe activation was greatest for short-term memory for words, while left anterior inferior frontal gyri activation (centered around Brodmann's area 47) was greatest for single word reading. Results suggest that temporal cortex (left > right) is a core region important for sentence comprehension beyond the short-term memory and semantic requirements inherent in processing sentences.     

遗忘型轻度认知障碍患者默认网络改变:基于后扣带回的脑连接研究

目的 探讨遗忘型轻度认知障碍(aMCI)患者后扣带回(PCC)功能连接的变化。 方法 选取性别、年龄和教育程度相匹配的18例aMCI患者(aMCI组)和20名健康老年人(健康老年组)进行GRE-EPI序列的静息状态fMRI检查,以PCC作为种子点,与全脑其他区域进行基于体素的时间序列相关分析。 结果 aMCI组与PCC有显著连接的脑区包括双侧背外侧前额叶(DLPFC)、左侧内侧前额叶(MPFC)及左侧前扣带回(ACC)、双侧顶下小叶(IPL)、双侧颞中回和双侧楔前叶。健康老年组与PCC有显著连接的脑区包括双侧DLPFC、右侧MPFC及ACC、双侧IPL、双侧颞中回、双侧颞下回和双侧楔前叶。健康老年组较aMCI组在右侧额上回、额中回、额下回的盖部及三角部、MPFC及ACC、颞中回及左侧楔前叶连接增强;aMCI组多个脑区功能连接较健康老年组增强,主要包括左侧半球的扣带回中部、顶上小叶(SPL)、IPL、颞中回及右侧IPL。 结论 PCC是aMCI患者脑代谢最先降低的区域,aMCI的PCC与多个功能区的连接破坏是其情节记忆功能减退的生物学基础,而其连接增强提示功能代偿可能。     

针刺足少阳胆经五输穴脑fMRI研究

目的 采用fMRI观察针刺足少阳胆经五输穴的脑功能区激活情况。方法 选取男性健康青年志愿者12名, 针刺右侧足少阳胆经五输穴, 在静息段与针刺段交替采集fMRI图像, 获得数据通过random effect法对数据行组分析, 以P <0.05的像素构成统计参数图, 即实验任务脑激活区, 按Talairach坐标行解剖定位, 获得试验任务激活的脑区。结果 受试者脑激活区包括左侧眶回(BA11)、双侧顶上小叶(BA7)、右侧颞上回(BA22)。负激活区包括右侧舌回(BA18)、右侧扣带回(BA24)、双侧顶上小叶(BA7)、右侧颞下回(BA20)。结论 针刺足少阳胆经五输穴可影响边缘系统、听觉系统、语言、记忆等。针灸叠加针刺引起对应的脑功能区变化是大脑传导通路重新整合与分配的结果。     

Evaluation of the dual route theory of reading: a metanalysis of 35 neuroimaging studies

Numerous studies concerned with cerebral structures underlying word reading have been published during the last decade. A few controversies, however, together with methodological or theoretical discrepancies between laboratories, still contribute to blurring the overall view of advances effected in neuroimaging. Carried out within the dual route of reading framework, the aim of this metanalysis was to provide an objective picture of these advances. To achieve this, we used an automated analysis method based on the inventory of activation peaks issued from word or pseudoword reading contrasts of 35 published neuroimaging studies. A first result of this metanalysis was that no cluster of activations has been found more recruited by word than pseudoword reading, implying that the first steps of word access may be common to word and word-like stimuli and would take place within a left occipitotemporal region (previously referred to as the Visual Word Form Area-VWFA) situated in the ventral route, at the junction between inferior temporal and fusiform gyri. The results also indicated the existence of brain regions predominantly involved in one of the two routes to access word. The graphophonological conversion seems indeed to rely on left lateralized brain structures such as superior temporal areas, supramarginal gyrus, and the opercular part of the inferior frontal gyrus, these last two regions reflecting a greater load in working memory during such an access. The lexicosemantic route is thought to arise from the coactivation of the VWFA and semantic areas. These semantic areas would encompass a basal inferior temporal area, the posterior part of the middle temporal gyrus, and the triangular part of inferior frontal gyrus. These results confirm the suitability of the dual route framework to account for activations observed in nonpathological subjects while they read.     

静息态功能磁共振成像评价原发性闭角型青光眼患者脑部局部一致性

目的 采用静息态功能磁共振成像(rs-fMRI)评价原发性闭角型青光眼(PACG)患者脑部局部一致性(ReHo)的改变。方法 对40例PACG患者(PACG组)及40名健康志愿者(对照组)进行rs-fMRI,计算全脑ReHo值,并进行统计学分析。结果 与对照组比较,PACG组右侧梭状回、左侧枕中回、左侧枕下回、左侧颞中回、双侧中央前回、左侧中央后回、左侧顶上小叶、左侧中央旁小叶的ReHo值均减低(P均<0.05);双侧小脑后叶、右侧额上回的ReHo值均增加(P均<0.05)。右侧梭状回、左侧枕中回ReHo值与视网膜纤维层厚度均呈正相关(r=0.452、0.472,P均<0.05)。右侧额上回ReHo值与视力呈负相关(r=-0.443,P=0.004)。结论 PACG患者存在视觉、感觉运动、情绪认知处理多个脑区自发性脑活动异常,且多个脑区ReHo值的改变与PACG疾病严重程度相关。     

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。     

99mTc-ECD SPECT SPM分析健康成人控尿状态下局部脑血流变化

目的 应用99mTc-双半胱乙酯(ECD)SPECT脑血流断层显像研究健康成人静息状态和控尿状态下脑血流的差异,定位控尿相关的大脑功能区.方法 对16名健康志愿者在静息状态下(排空膀胱)行SPECT脑血流断层显像后,注射呋塞米,在膀胱充盈状态应用同等条件再次显像,前后两次采集数据相减,获得控尿状态图像.采用统计参数图(SPM)软件进行分析.结果 在控尿状态下,右侧顶叶、双侧额上回、右侧额下回和右侧颞上回、左侧屏状核的脑血流明显增高.结论 正常生理状态下,大脑控尿与右侧顶叶、双侧额上回、右侧额下回、右侧颞上回和左侧屏状核密切相关.联合应用SPECT脑功能显像及SPM分析软件可以更方便、快捷地定位大脑功能区.