脑功能磁共振成像及其处理分析技术对神经科学研究的价值

目的：对近年来脑功能磁共振成像及其处理和分析技术进行了讨论和综述．以阐明图像处理和分析投术在应用脑功能磁共振成像技术进行脑科学研究的重要作用．资料来源：应用计算机检索MPdline 1996—0-／2004-12期间与脑功能磁共振成像及其处理和分析技术相关文章，检索词为“功能磁共振成像”和“processing and analvshsisl,ICA．FCM”、分别组合进行检索，限定文章语言为English，同时利用yahoo搜索引擎进行检索．检索词同上。资料选择：对资料进行初审、选取那些有关脑功能磁共振成像及其处理和分析方面的文献。资料提炼：共搜集到35篇英文全文．2篇中文，这此资料在对脑功能磁共振图像的处理和分析方面均具有较新的进展性。资料综合：由于功能磁共振成像在成像原理上自其特殊性，其目的是标记（或映射）时应于大脑在执行特殊任务或受到某种刺激时脑的激活区域，在功能磁共振图像中，功能活动信号表现为微弱信号，难以用肉眼区分出哪些是功能活动区域。因此对功能磁共振成像得到的图像数据的处理和分析的目的是从图像中提取出微弱的功能活动信号，这与一般意义上的图像处理和分析有所不同，将搜集到的35篇英文文献，2篇中文文献按照处理方法是否依赖于刺激时程，把图像处理方法分成假设驱动的方法和数据驱动的方法，并分析和讨论这些方法各自的特点。结论：图像处理分析技术在利用脑功能磁共振成像对神经科学的研究中具有重要的应用价值．图像处理和分析技术在功能磁共振成像实验中占有极其重要的地位，它对于最终脑功能的精确定位是必不可少的关键步骤。     

磁共振成像在大脑功能研究中的作用及价值

目的：介绍国内、外近15年来功能磁共振成像在人类大脑功能区定位方面的研究概况，以期进一步了解功能磁共振成像的作用与价值。 资料来源：应用计算机检索美国MEDLINE数据库1990／2005期间的相关文章，限定文章语言种类为英文，检索词为“功能磁共振，大脑”。 资料选择：对资料进行初审，选择大脑功能研究中应用功能磁共振为研究方法的研究文献查找全文。纳入标准：（1）功能磁共振作为主要研究手段。（2）探讨大脑的运动、感觉、听觉、视觉、认知功能有关的文章。（3）针对正常受试者脑功能定位的研究。排除标准：（1）与大脑的运动、感觉、听觉、视觉、认知功能无关的文章。（2）仅对于异常受试者所做的研究。（3）重复研究。（4）原文无英文文题文章。 资料提炼：共收集到相关文献6144篇，按上述标准纳入18篇，其余文献均被排除。 资料综合：（1）运动功能定位有关的2篇，关于改变手指运动方式进行脑功能区的定位。（2）与感觉功能定位有关的4篇，其中1篇是通过简单触觉刺激进行脑功能区的定位，3篇是观察通过针灸刺激穴位时对脑功能区的定位。（3）与视觉功能定位有关的3篇，其中2篇是通过简单视觉刺激对视觉中枢的定位，1篇是关于交替刺激双眼时脑功能区的定位。（4）与听觉功能定位有关的3篇．其中2篇是关于通过不同的听觉刺激方式进行中枢的定位，1篇是关于正常与异常受试者在相同刺激下脑功能区定位的不同。（5）与语言功能定位有关的3篇，均是与1篇与运动语言功能区有关，1篇与听觉语言功能区有关，1与视觉语言功能区定位有关。（6）与认知功能定位有关的2篇。均是与记忆有关的文献。（7）1篇实关于fMRI基本原理介绍方面的文献。 结论：功能磁共振对脑功能区的定位对比其他方法相对更准确。更方便，更直观。针对不同脑功能区，不仅能显示脑功能区激活区的部位、大小和范围，而且可直接显示激活区所在确切解剖位置。通过对机体的刺激方法和方式的探索、硬件技术的提高、图像后处理技术的提高，功能磁共振将在阐明人脑的功能方面发挥巨大的作用。     

磁共振成像在大脑功能研究中的作用及价值

目的:介绍国内、外近15年来功能磁共振成像在人类大脑功能区定位方面的研究概况,以期进一步了解功能磁共振成像的作用与价值。资料来源:应用计算机检索美国MEDLINE数据库1990/2005期间的相关文章,限定文章语言种类为英文,检索词为“功能磁共振,大脑”。资料选择:对资料进行初审,选择大脑功能研究中应用功能磁共振为研究方法的研究文献查找全文。纳入标准:①功能磁共振作为主要研究手段。②探讨大脑的运动、感觉、听觉、视觉、认知功能有关的文章。③针对正常受试者脑功能定位的研究。排除标准:①与大脑的运动、感觉、听觉、视觉、认知功能无关的文章。②仅对于异常受试者所做的研究。③重复研究。④原文无英文文题文章。资料提炼:共收集到相关文献6144篇,按上述标准纳入18篇,其余文献均被排除。资料综合:①运动功能定位有关的2篇,关于改变手指运动方式进行脑功能区的定位。②与感觉功能定位有关的4篇,其中1篇是通过简单触觉刺激进行脑功能区的定位,3篇是观察通过针灸刺激穴位时对脑功能区的定位。③与视觉功能定位有关的3篇,其中2篇是通过简单视觉刺激对视觉中枢的定位,1篇是关于交替刺激双眼时脑功能区的定位。④与听觉功能定位有关的3篇,其中2篇是关于通过不同的听觉刺激方式进行中枢的定位,1篇是关于正常与异常受试者在相同刺激下脑功能区定位的不同。⑤与语言功能定位有关的3篇,均是与1篇与运动语言功能区有关,1篇与听觉语言功能区有关,1与视觉语言功能区定位有关。⑥与认知功能定位有关的2篇。均是与记忆有关的文献。⑦1篇实关于fMRI基本原理介绍方面的文献。结论:功能磁共振对脑功能区的定位对比其他方法相对更准确,更方便,更直观。针对不同脑功能区,不仅能显示脑功能区激活区的部位、大小和范围,而且可直接显示激活区所在确切解剖位置。通过对机体的刺激方法和方式的探索、硬件技术的提高、图像后处理技术的提高,功能磁共振将在阐明人脑的功能方面发挥巨大的作用。     

听觉脑功能磁共振成像

听觉脑功能磁共振成像是磁共振功能成像(functionalmagneticresonanceimaging,fMRI)的一种,fMRI是一种安全的影像学检查手段,在完全无创的条件下对人脑进行功能分析,一次成像可同时获得解剖与功能影像,而且对人体无辐射损伤。尽管fMRI技术和方法还在不断发展和完善,但其可靠性和实用性是不容置疑的。它对听觉障碍患者的术前诊断、手术计划的制定、术后患者康复程度的评估,将会发挥越来越重要的作用。     

磁共振灌注成像分析原理及其对脑卒中发病预测评估的价值

目的：综述近几年国外有关磁共振灌注成像的基本原理及在脑卒中发病预测评估应用方面的研究近况。 资料来源：应用计算机检索Medline1990／2005与磁共振灌注成像的基本原理及其在脑卒中应用相关的文章，检索词为“pedusion-weighted imaging，Stroke”．“cerebral perfusion，stroke”，“cerebral blood flow”并限定文章语言种类为“English”。 资料选择：对资料进行初审，选取有关磁共振灌注成像及在脑卒中应用方面的相关文献，然后筛除明显不随机临床试验的研究，对剩余的文献查找全文，纳入标准为随机对照临床研究（RCT），无论是否为单盲，双盲或非盲法。 资料提炼：共收集到相关文献21篇，排除6篇重复的同一研究，对剩余的15篇进行综述。 资料综合：在符合入选标准的15篇文献中，共包括91例患者，从磁共振灌注成像的基本技术、磁共振对比剂的种类、脑卒中后脑缺血的阶段、磁共振灌注成像的常用参数及意义分别论述了磁共振灌注成像的基本原理；从脑卒中后脑血流量的变化、预测脑缺血缺氧的发展变化、评估梗死的范围及判断预后等方面，阐述了磁共振灌注成像在脑梗死中的应用。 结论：磁共振灌注成像可用来研究梗死后血流量的变化，可以提供必要的血流动力学参数；磁共振灌注成像也可以用来评估最后梗死的范围，判断脑卒中的预后。     

孤独症磁共振脑功能成像研究

孤独症是起病于婴幼儿期严重的慢性神经精神障碍，涉及语言、认知、社会交往能力等多种障碍。磁共振脑功能成像是通过血氧水平依赖法检测脑实质血管内血氧浓度变化，以显示相应的脑功能区。孤独症的磁共振脑功能成像研究主要集中在注意力、运动、语言和面部识别等方面，发现孤独症患者的脑功能区与正常对照组相比较有部分区别。目前孤独症患者脑功能磁共振检查研究尚处于起步阶段，病例较少，脑功能实验设计较为简单。随着研究的逐步深入，脑功能磁共振检查将会对孤独症的脑功能异常做出综合评价并指导临床。     

听觉脑功能磁共振成像

听觉脑功能磁共振成像是磁共振功能成像(functional magnetic resonance imaging,fMRI)的一种，fMRI是一种安全的影像学检查手段，在完全无创的条件下对人脑进行功能分析，一次成像可同时获得解剖与功能影像，而且对人体无辐射损伤。尽管fMRI技术和方法还在不断发展和完善，但其可靠性和实用性是不容置疑的。它对听觉障碍患者的术前诊断、手术计划的制定、术后患者康复程度的评估，将会发挥越来越重要的作用。     

脑功能磁共振成像及其应用进展

功能磁共振成像是近 10余年来在传统的磁共振成像技术的基础上迅速发展起来的一种新的成像技术。与传统的磁共振成像技术不同的是 ,功能磁共振成像得到的是人脑在执行某项任务或受到某种刺激时的功能映射图 ,而不是人脑的解剖图像。它能够确定人脑在执行某项任务或受到某种刺激时大脑的哪些区域被激活。目前 ,功能磁共振成像技术在国外已经得到了广泛的应用 ,其应用领域涉及到脑科学研究的各个领域 ,如认知科学、心理学、神经科学、药物滥用以及临床应用等。国内在这一方面的研究和应用还刚刚开始。本文对近年来功能磁共振成像及其在国内外…     

脑活动功能磁共振成像研究进展

本文介绍了人脑活动功能磁共振成像(fMRI)的生物物理基础研究的现状和关键技术的进展,综述了这些技术在人脑功能研究和临床疾病诊疗中的应用和发展前景.     

脑功能磁共振成像的研究进展

在人类跨入新世纪的时候 ,脑神经科学也进入了一个关键时期。正电子发射体层扫描 (ｐｏｓｉｔｉｏｎｅｍｉｓｓｉｔｉｏｎｔｏｍｏｇｒａ ｐｈｙ,ＰＥＴ)和功能性磁共振成像 (ｆｕｎｃ ｔｉｏｎａｌｍａｇｎｅｔｉｃｒｅｓｏｎａｎｃｅｉｍａｇｉｎｇ ,ｆＭＲＩ)技术发挥了重要作用 ,而ｆＭＲＩ为临床ＭＲ诊断从单一形态学研究到形态与功能相结合的系统研究开辟了一条崭新的道路 ,近年来很多学者已经对其进行了深入研究 ,现将ｆＭＲＩ相关研究及新进展综述如下。1　ｆＭＲＩ发展史回顾美国学者Ｏｇａｗａ[1] 在 1990年首先发现血液中的脱氧…     

Item analysis in functional magnetic resonance imaging

Behavioral and neuroimaging studies of cognition frequently test hypotheses regarding mental processing of different stimulus categories (e.g. verbs, faces, animals, scenes, etc.). The conclusions of such studies hinge upon the generalizability of their findings from the specific stimuli used in the experiment to the category as a whole. This type of generalizability is explicitly tested in behavioral studies, using "item analysis". However, generalizability to stimulus categories has up until now been assumed in neuroimaging studies, without employing item analysis for statistical validation. Here we apply item analysis to a functional magnetic resonance imaging study of nouns and verbs, demonstrating its theoretical importance and feasibility. In the subject-wise analysis, a left prefrontal and a left posterior-temporal region of interest showed putative grammatical class effects. An item-wise analysis revealed, however, that only the left posterior-temporal effect was generalizable to the stimulus categories of nouns and verbs. Taken together, the findings of the subject- and item-wise analyses suggest that grammatical-class effects in the left prefrontal cortex depend on the particular word stimuli used, rather than reflecting categorical differences between nouns and verbs. This empirical example illustrates that item analysis not only is sufficiently powered to detect task relevant changes in BOLD signal but also can make theoretically important distinctions between findings that generalize to the item populations, and those that do not.     

Brain processing of visual sexual stimuli in healthy men: a functional magnetic resonance imaging study

The brain plays a central role in sexual motivation. To identify cerebral areas whose activation was correlated with sexual desire, eight healthy male volunteers were studied with functional magnetic resonance imaging (fMRI). Visual stimuli were sexually stimulating photographs (S condition) and emotionally neutral photographs (N condition). Subjective responses pertaining to sexual desire were recorded after each condition. To image the entire brain, separate runs focused on the upper and the lower parts of the brain. Statistical Parametric Mapping was used for data analysis. Subjective ratings confirmed that sexual pictures effectively induced sexual arousal. In the S condition compared to the N condition, a group analysis conducted on the upper part of the brain demonstrated an increased signal in the parietal lobes (superior parietal lobules, left intraparietal sulcus, left inferior parietal lobule, and right postcentral gyrus), the right parietooccipital sulcus, the left superior occipital gyrus, and the precentral gyri. In addition, a decreased signal was recorded in the right posterior cingulate gyrus and the left precuneus. In individual analyses conducted on the lower part of the brain, an increased signal was found in the right and/or left middle occipital gyrus in seven subjects, and in the right and/or left fusiform gyrus in six subjects. In conclusion, fMRI allows to identify brain responses to visual sexual stimuli. Among activated regions in the S condition, parietal areas are known to be involved in attentional processes directed toward motivationally relevant stimuli, while frontal premotor areas have been implicated in motor preparation and motor imagery. Further work is needed to identify those specific features of the neural responses that distinguish sexual desire from other emotional and motivational states.     

Pediatric magnetic resonance imaging techniques

Optimization of the MR image requires an understanding of technical parameters, pulse sequences, artifacts, and the use of contrast agents. More technical information and in-depth details about the practical concepts for performing MRI in children can be found in the references accompanying this article.     

磁共振功能成像技术在脑胶质瘤诊治中的应用

磁共振脑功能成像技术(f MRI)的着眼点在于利用某些特定的原子或化合物在磁场中的不同表现而对病变进行分析,从不同角度反映正常脑组织和肿瘤组织的功能和代谢变化,在研究和诊断中的作用正日益突出。在脑功能区或附近、深部脑胶质瘤手术致残率高、预后差。在常规MRI反映脑胶质瘤的解剖特征的基础上,f MRI提供有关肿瘤代谢、生化、脑白质纤维束的走行、脑功能区定位等信息,降低脑胶质瘤术后并发症等方面具有重要的应用价值。本文就目前几种常见的f MRI成像技术在胶质瘤诊治中的应用进行总结。     

Brain activation patterns during imagined stance and locomotion in functional magnetic resonance imaging

Posture and gait are sensorimotor actions that involve peripheral, spinal, and supraspinal structures. To investigate brain activity during stance and locomotion, 13 healthy subjects were asked to stand, walk, run, and lie down; subsequently, they were trained to imagine standing, walking, running, and lying [imagined lying as rest condition in functional magnetic resonance imaging (fMRI)]. Separate and distinct activation/deactivation patterns were found for the three imagined conditions: (1) standing imagery was associated with activation in the thalamus, basal ganglia, and cerebellar vermis; (2) walking imagery was associated with activation in the parahippocampal and fusiform gyri (areas involved in visuospatial navigation), occipital visual areas, and in the cerebellum; (3) running imagery caused a predominantly cerebellar activation in the vermis and adjacent hemispheres (six times larger than during imagination of walking or standing), but activations in the parahippocampal and fusiform gyri were smaller than during walking. Deactivations were found for walking and running, but not for standing imagery. They were located in the vestibular (posterior insula, superior temporal gyrus, supramarginal gyrus) and somatosensory (postcentral gyrus) cortex with right-hemispheric dominance. These findings support the concept of a hierarchical organization of posture and locomotion. Automated locomotion, for example, running, is based on spinal generators whose pace is driven by the cerebellar locomotor region. Deactivation in the vestibular and somatosensory cortex prevents adverse interactions with the optimized spinal pattern and sensory signals; this confirms earlier findings of a multisensory inhibition during unhindered locomotion. During slow walking, spatial navigation, mediated by the parahippocampal cortex, becomes more important. Postural control during standing involves a low intensity cerebellar activity and sensorimotor control via the thalamus and basal ganglia.     

Event-related single-shot volumetric functional magnetic resonance inverse imaging of visual processing

Developments in multi-channel radio-frequency (RF) coil array technology have enabled functional magnetic resonance imaging (fMRI) with higher degrees of spatial and temporal resolution. While modest improvement in temporal acceleration has been achieved by increasing the number of RF coils, the maximum attainable acceleration in parallel MRI acquisition is intrinsically limited only by the amount of independent spatial information in the combined array channels. Since the geometric configuration of a large-n MRI head coil array is similar to that used in EEG electrode or MEG SQUID sensor arrays, the source localization algorithms used in MEG or EEG source imaging can be extended to also process MRI coil array data, resulting in greatly improved temporal resolution by minimizing k-space traversal during signal acquisition. Using a novel approach, we acquire multi-channel MRI head coil array data and then apply inverse reconstruction methods to obtain volumetric fMRI estimates of blood oxygenation level dependent (BOLD) contrast at unprecedented whole-brain acquisition rates of 100 ms. We call this combination of techniques magnetic resonance Inverse Imaging (InI), a method that provides estimates of dynamic spatially-resolved signal change that can be used to construct statistical maps of task-related brain activity. We demonstrate the sensitivity and inter-subject reliability of volumetric InI using an event-related design to probe the hemodynamic signal modulations in primary visual cortex. Robust results from both single subject and group analyses demonstrate the sensitivity and feasibility of using volumetric InI in high temporal resolution investigations of human brain function.