脑功能磁共振成像研究进展

主要综述fMRI产生的历史、成像原理、成像技术和方法、已经取得的成绩以及将来研究发展的方向等。fMRI产生技术广泛应用的20世纪90年代,主要受快速成像技术的影响,从有创走向无创,从而受到神经、认知和心理科学领域的极大关注。fMRI原理是根据神经元兴奋后局部氧耗与血流增幅不一致,而BOLD效应机制成像,间接显示神经元活动。成像主要采用平面回波成像（EPI）和快速小角度激发（FLASH）技术、二者在时间和空间分辨率上各有优劣。最后几年来,fMRI技术对脑功能的研究已取得了巨大的成绩,估计将在这一领域继续拥有非常重要的地位。将来fMRI可能主要在BOLD效应的生理过程、临床应用以及高场磁体的应用等领域进一步展开。     

丙泊酚Wada试验与功能磁共振在颞叶癫痫词汇记忆功能偏侧化评估中的应用

目的 比较丙泊酚Wada试验与功能磁共振(fMRI)在左颞叶癫痫患者术前记忆功能偏侧化预测中的一致性和敏感性. 方法 对广州军区广州总医院自2009年10月至2011年10月收治的8例左前颞叶切除的癫痫患者术前进行丙泊酚Wada试验和fMRI记忆功能偏侧化评估,结合韦氏记忆测验结果,比较两者记忆功能偏侧化评估的一致性与预测记忆变化的敏感性. 结果 fMRI词汇记忆半球、内侧颞叶功能偏侧化与Wada试验功能偏侧化判定的一致率分别为57.0％和71.4％,术后记忆商数、词汇匹配以及智力改变与fMRI词汇记忆内侧颞叶功能偏侧化指数呈显著相关(r=-0.314,P=0.037;r=-0.387,P=.013;r=0.116,P=0.020),与Wada试验功能偏侧化指数无相关性(r=-0.442,P=.077;r=-0.241,P=0.237;r=-0.070,P=0.107). 结论 丙泊酚Wada试验和fMRI记忆功能偏侧化评估一致性因感兴趣区选择方法不同而不同.相对于Wada试验,fMRI记忆功能偏侧化指数在预测患者术后词汇记忆下降的过程中敏感性更高.     

脑磁共振功能成像的基本原理及应用

脑磁共振功能成像是一种新的研究人脑功能的方法 ,具有无创、时间和空间分辨率高的特点 ,逐渐应用于神经科学的多个领域。在阐明高级神经生理和神经心理活动方式和皮层间的功能联系、术中导航以最大限度切除功能皮层病变并减少手术并发症、了解脑肿瘤的分化程度和预后判断、揭示神经和精神疾病皮层功能异常的病理生理改变等方面 ,均显示了较高的应用价值。本文综述了该方法的原理、技术要求、信号分析及其在脑功能的基础研究和临床上的应用。     

工作记忆与脑的功能磁共振成像

工作记忆是临时信息编码、保持和提取的过程 ,是学习记忆研究的热点之一。功能磁共振作为一种新型无损伤技术 ,为研究工作记忆提供了一个新的途径。本文对功能磁共振的原理、实验设计和目前工作记忆功能磁共振检查的研究进展进行综述。     

工作记忆与脑的功能磁共振成像

工作记忆是临时信息编码、保持和提取的过程,是学习记忆研究的热点之一.功能磁共振作为一种新型无损伤技术,为研究工作记忆提供了一个新的途径.本文对功能磁共振的原理、实验设计和目前工作记忆功能磁共振检查的研究进展进行综述.     

书写痉挛脑功能磁共振成像研究

目的 应用脑功能磁共振成像（fMRI）技术,观察书写痉挛患者痉挛性书写脑功能区激活特点,探讨书写痉挛可能发病机制.方法 采用fMRI组块设计,分别获得10例书写痉挛患者和10名年龄、性别匹配健康对照组执行默写、手写、笔写任务时的平均脑功能激活图,同时通过一般线性分析法产生“笔写减手写”及“笔写减默写”的差异脑功能图.结果 书写痉挛患者进行书写任务时,受累手对侧基底节区,特别是壳核（激活体素个数864）,较健康对照组（激活体素个数54）显著激活;运动皮质（第一运动区、辅助运动区、运动前区）及同侧小脑较健康对照亦有明显激活;而进行手指写和默写任务时两组间差异并不明显;＂笔写减手写＂及＂笔写减默写＂差异脑功能图发现书写痉挛患者在除去手指写运动及语言处理相关影响后上述脑区仍有明显激活,健康对照组则皮质下结构激活消失,运动相关皮质激活亦明显减少.结论 书写痉挛患者执行笔写任务时上述脑区尤其皮质下结构异常激活与书写痉挛发生存在一定关联,基底节区及相应皮质-皮质下环路功能紊乱,可能在书写痉挛发病机制中起到重要作用.     

正常人词语流畅性作业的脑功能磁共振成像研究

目的 利用功能磁共振成像(fMRI)技术探讨词语流畅性作业的脑功能定位。方法对18名健康志愿者进行词语流畅性作业的fMRI检查,fMRI用梯度回波-平面回波成像序列采集数据,经工作站处理后获功能图像。结果 经Fisher精确检验法,健康志愿者的双侧额上回、双侧额中回、右侧额下回及右侧扣带回的激活脑区计数,与理想激活脑区计数的差异均无显著性(P>0.05),其余脑区激活计数的差异均有显著性(P<0.05)。结论 双侧额叶背外侧及右侧额叶腹外侧可能参与长时记忆的提取过程,其中额叶背外侧可能参与核查及管理工作,而额叶腹外侧可能参与搜寻特异目标的过程。     

精神分裂症功能磁共振成像研究近况

本文介绍功能磁共振成像在精神分裂症的脑功能定位和功能连接的研究近况。     

癫痫磁共振功能成像研究进展

实现对癫痫病灶更精确的功能定位 ,始终是癫痫病学最为关注的研究方向之一。为达到这一目的 ,临床上采用多种技术手段 ,如神经电生理、神经影像学和近 10来年发展起来的功能影像技术等。ＥＥＧ的问世对癫痫的诊断产生了划时代的影响 ,脑磁图 (ＭＥＧ)和偶极子 (ｄｉｐｏｌｅ)技术的应用使癫痫灶的定位水平不断提高 ,至今 ,皮层电极和深部电极仍然是术中判断癫痫灶位置不可缺少的检查方法 ;ＣＴ、ＭＲＩ为癫痫的病因诊断提供了直观、清晰的解剖形态学图像 ;正电子发射体层摄影术 (ＰＥＴ)、单光子发射计算机体层摄影术(ＳＰＥＣＴ)、磁共振血…     

针刺内关穴对阿尔茨海默病脑功能磁共振成像的影响

目前,随着社会老龄化,关于老年痴呆的中西医研究较多,但尚无针刺治疗对阿尔茨海默病 (Alzheimer’sdisease,AD)患者脑功能成像方面的研究报道,我们于 2004年 3—8月通过针刺内关穴研究针刺对AD患者脑功能活动的影响,旨在找到AD治疗的客观基础。对象和方法1. 研究对象: 6例A     

健康人脑空间工作记忆的脑功能磁共振研究

目的 通过功能磁共振成像(unctional magnetic resonance imaging, fMRI)技术研究健康人脑空间工作记忆的功能脑区.方法 10名右利手健康志愿者进行空间工作记忆任务的同时进行fMRI扫描,实验采用组块设计和SPM99软件进行数据分析和脑功能区定位.结果 大脑皮质所激活的主要脑区有双侧顶叶(BA7/40,BA:Brodmann area,布鲁德曼分区),双侧额叶(BA6/9/47),双侧枕颞交界处(BA19/37);被激活的大脑皮质下结构有右侧尾状核、左侧丘脑和左侧中脑黑质;双侧小脑也均被显著激活(P<0.001).结论 人脑处理空间工作记忆信息是由大脑皮质下结构及小脑与大脑皮质共同完成的.     

空间记忆广度的脑功能磁共振研究

目的本实验拟通过功能磁共振研究参与正常人空间记忆广度任务的脑功能区和特点。方法10名右利手健康志愿者进行一项空间记忆广度任务作业的同时进行脑功能磁共振扫描,实验采用组块设计,实验任务与对照任务交替进行,数据采用SPM99软件进行数据分析和脑功能区定位。结果当统计阈值设定为P(0.0001时,被试者的双侧Brodmann区(Brodmann area,BA)6区(额中下回)、右BA9区(额中下回)、左额下回BA47区、双侧顶叶BA7区(楔前叶、顶上小叶)、双侧顶叶BA40区(缘上回),右枕叶BA18、19区、右海马回BA30区、左枕颞交界处BA37区、双侧顶叶中央后回BA3区、左顶叶中央后回BA2区、右中央前回BA4区及左中脑黑质、右小脑均有激活,以顶叶的激活最为显著,其次为额叶、枕叶,其中额叶的BA9区和枕叶的BA18、19区及海马回、小脑的激活有极其明显的右侧半球优势;当统计阈值设定为P(0.001时,脑激活区增加了右前扣带回BA25区,右侧额下回BA47区、左额叶BA9区,左侧枕叶BA17、18、19区及右屏状核,左丘脑侧后核。结论与空间记忆广度有关的主要脑区有BA9、6、7、40、19区和海马回、小脑。它们在进行短时空间记忆任务时所起的作用不同。通过fMRI的研究,揭示了大脑进行空间信息的处理过程。     

A functional magnetic resonance imaging investigation of episodic memory after traumatic brain injury

Traumatic brain injury often negatively impacts episodic memory; however, studies of the neural substrates of this impairment have been limited. In this study, both encoding and recognition of visually presented stimuli were examined with functional magnetic resonance imaging. Twelve adults with chronic complicated mild, moderate, and severe injuries were compared with a matched group of 12 controls. Behavioral task performance did not differentiate the groups. During neuroimaging, however, the group of individuals with traumatic brain injury exhibited increased activation, as well as increased bilaterality and dispersion as compared to controls. Findings are discussed in terms of increased resource recruitment.     

A functional magnetic resonance imaging study of working memory abnormalities in schizophrenia.

BACKGROUND: Previous neuroimaging studies of working memory (WM) in schizophrenia, typically focusing on dorsolateral prefrontal cortex, yield conflicting results, possibly because of varied choice of tasks and analysis techniques. We examined neural function changes at several WM loads to derive a more complete picture of WM dysfunction in schizophrenia. METHODS: We used a version of the Sternberg Item Recognition Paradigm to test WM function at five distinct loads. Eighteen schizophrenia patients and 18 matched healthy controls were scanned with functional magnetic resonance imaging at 3 Tesla. RESULTS: Patterns of both overactivation and underactivation in patients were observed depending on WM load. Patients' activation was generally less responsive to load changes than control subjects', and different patterns of between-group differences were observed for memory encoding and retrieval. In the specific case of successful retrieval, patients recruited additional neural circuits unused by control subjects. Behavioral effects were generally consistent with these imaging results. CONCLUSIONS: Differential findings of overactivation and underactivation may be attributable to patients' decreased ability to focus and allocate neural resources at task-appropriate levels. Additionally, differences between encoding and retrieval suggest that WM dysfunction may be manifested differently during the distinct phases of encoding, maintenance, and retrieval.     

Localization of semantic processing using functional magnetic resonance imaging

The relationship between the functional components of language and the anatomic foci of their neural systems represents a central issue in cognitive neuroscience. Conflicting results from a number of laboratories using positron emission tomography (PET) imaging techniques have led to a significant controversy over the specific neuroanatomic sites engaged by semantic processing. We report here results of an experiment designed to address this controversy, that is, whether semantic processing activates temporal and/or frontal brain regions. In this experiment we used cognitive tasks that emphasized either semantic or phonological information processing but that were similar on both memory search and responce generation components, together with functional magnetic resonance imaging, to examine the neuroanatomic loci of lexical-semantic as opposed to phonological processing. We studied nine right-handed men performing two silent generation tasks: rhyme, and semantic category. The former focuses on word form (phonological information) while the latter focuses on word meaning (semantic information). By “phonological” we mean the process of apprehending the sound structures of language. By “semantic” we mean information about the word's contextually specified meanings. Semantic processing makes demands on, and activates widespread areas within, brain including the inferior frontal regions bilaterally and the left posterior temporal region. Phonological processing engages a more restricted neuroanatomic assembly involving primarily anterior left temporal lobe sites. © 1995 Wiley-Liss, Inc.     

Diffusion magnetic resonance imaging connectome features are predictive of functional lateralization of semantic processing in the anterior temporal lobes

Assessment of regional language lateralization is crucial in many scenarios, but not all populations are suited for its evaluation via task‐functional magnetic resonance imaging (fMRI). In this study, the utility of structural connectome features for the classification of language lateralization in the anterior temporal lobes (ATLs) was investigated. Laterality indices for semantic processing in the ATL were computed from task‐fMRI in 1038 subjects from the Human Connectome Project who were labeled as stronger rightward lateralized (RL) or stronger leftward to bilaterally lateralized (LL) in a data‐driven approach. Data of unrelated subjects (n = 432) were used for further analyses. Structural connectomes were generated from diffusion‐MRI tractography, and graph theoretical metrics (node degree, betweenness centrality) were computed. A neural network (NN) and a random forest (RF) classifier were trained on these metrics to classify subjects as RL or LL. After classification, comparisons of network measures were conducted via permutation testing. Degree‐based classifiers produced significant above‐chance predictions both during cross‐validation (NN: AUC–ROC[CI] = 0.68[0.64–0.73], accuracy[CI] = 68.34%[63–73.2%]; RF: AUC–ROC[CI] = 0.7[0.66–0.73], accuracy[CI] = 64.81%[60.9–68.5]) and testing (NN: AUC–ROC[CI] = 0.69[0.53–0.84], accuracy[CI] = 68.09[53.2–80.9]; RF: AUC–ROC[CI] = 0.68[0.53–0.84], accuracy[CI] = 68.09[55.3–80.9]). Comparison of network metrics revealed small effects of increased node degree within the right posterior middle temporal gyrus (pMTG) in subjects with RL, while degree was decreased in the right posterior cingulate cortex (PCC). Above‐chance predictions of functional language lateralization in the ATL are possible based on diffusion‐MRI connectomes alone. Increased degree within the right pMTG as a right‐sided homologue of a known semantic hub, and decreased hubness of the right PCC may form a structural basis for rightward‐lateralized semantic processing.     

精神分裂症脑结构的核磁共振研究

目的：采用核磁共振技术（MRI）分析精神分裂症患者的脑结构改变。方法：以精神分裂症住院患者101例为对象,正常30例为对照,作头颅核磁共振扫描。结果：病例组第三脑室显著增宽,尾状核体积较大,海马增厚,各部位海马信号强度减弱。结论：精神分裂症患者脑萎缩明显,尾状核增大。