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。     

注意训练对非流畅性失语患者双任务范式干扰效应影响的功能磁共振研究

目的考察注意训练对非流畅性失语患者汉字加工任务中双任务范式干扰效应的激活区及偏侧化指数的影响。方法将20例脑卒中后非流畅性失语患者分成实验组及对照组各10例,分别给予注意训练和认知训练,每次30 min,每周5次,共4周。训练前后分别采用组块设计对患者汉字加工任务进行功能磁共振扫描,比较训练前后双任务范式干扰效应的激活区及偏侧化指数。结果训练前两组患者均为右侧额下回、双侧顶叶、双侧小脑显著激活;训练后,实验组各激活区更加显著,而对照组各激活区未见显著变化;训练前两组患者均呈右半球优势;训练后实验组呈左半球优势,而对照组仍呈右半球优势。结论在双任务范式干扰效应中,右侧额下回、双侧顶叶、双侧小脑可能在知觉注意阶段对解决双重任务干扰非常重要;注意训练后激活更加显著;注意训练可能使失语症患者语义加工产生了功能重组。     

利用fMRI和双手交替运动模式研究脑肿瘤所致的运动功能重组

目的应用fMRI研究双手交替运动模式下中央沟附近脑肿瘤患者运动功能重组的方式及特征.方法6名正常受试者和14名脑肿瘤患者采用双手交替对指运动模式行fMRI扫描,比较正常受试者与脑肿瘤患者脑激活的异同.结果正常人单手对指运动主要激活运动手对侧的大脑半球和同侧小脑半球.脑肿瘤患者非受累手运动所致的激活与正常受试者基本相同;而当受累手运动时,则出现运动功能的重组,包括肿瘤对侧正常半球内M1区的代偿性激活、肿瘤侧半球MI活动的减弱、双侧SMA等次级运动中枢激活区的增大以及双侧小脑半球的激活.结论采取双手交替运动模式,fMRI不仅显示了受累侧运动区的变形与移位,而且揭示了一种新的功能重组模式,即运动功能重组可能涉及分布于全脑的整个神经网络.     

基于功能性近红外光谱技术的吞咽相关任务大脑皮质功能偏侧化研究

摘要 目的：采用功能性近红外光谱技术（fNIRS）研究吞咽相关任务时大脑皮质激活及偏侧化情况。 方法：纳入22名健康成年被试,在fNIRS采集过程中执行咀嚼及舌尖滑动任务,对任务激活脑区进行分析,并计算不同脑区的偏侧化指数。 结果：在执行咀嚼任务时,左侧初级运动皮层（primary motor cortex,PMC）、左侧初级躯体感觉皮层（primary somatosensory cortex, PSC）、左侧运动前区/运动辅助区（pre-motor and supplementary motor cortex,pSMC）、左侧缘上回（supramarginal gyrus, SMG）,右侧背外侧前额叶（dorsolateral prefrontal cortex,DLPFC）、右侧额叶眼动区（frontal eye fields, FEF）、右侧颞上回（superior temporal gyrus,STG）及颞中回（middle temporal gyrus,MTG）、右侧额极区（frontopolar area, FPA）及右侧额下回三角区（pars triangularis, PTG）脑区明显激活。舌尖滑动任务则表现为双侧PMC、双侧PSC、双侧pSMC及左侧SMG脑区明显激活。同时在全脑及PMC、pSMC、PSC等脑区的激活呈现偏侧化模式。咀嚼任务主要表现为局部脑区的左侧偏侧化激活,舌尖滑动任务表现为局部脑区的右侧偏侧化激活。全脑左右半球间的偏侧化变异性较大,且与利手无关。 结论：fNIRS可应用于吞咽相关的脑功能研究。PMC、pSMC、PSC、SMG、STG、MTG、PTG等脑区与吞咽特定过程的神经调控有关,并表现为偏侧化激活模式,并且随着吞咽活动的进行,相关脑区的激活可能存在从左侧逐渐向右侧偏侧化的转变。     

功能磁共振成像评价动词生成任务中运动前区激活

目的 观察运动前区(PMA)在动词生成任务fMRI试验中的激活情况,探讨其在语言表达功能中的可能作用.方法 对23名受试者接受fMRI试验.试验任务为组块设计的动词生成任务:对照内容为黑色屏幕中心呈现的白色 "+";刺激任务为生成动词,要求受试者根据给出的单字名词,组成一个相关的动词词语.采用SPM2软件进行数据后处理,采用单样本t-检验的组分析方法获得平均脑激活图,观察PMA激活情况.结果 11名符合试验要求的受试者的数据列入组分析,脑激活区包括Broca区、右侧额下回后部、双侧PMC、双侧SMA、左侧顶后皮层、右侧丘脑、左侧基底节区、右侧小脑半球和右侧颞叶后部.全脑最强激活区为左侧PMA.结论 PMA在动词生成任务中具有重要作用,可能涉及语音处理、想象运动、词语提取和信息的高级调控等多个方面.     

汉字情景记忆时皮层定位的fMRI研究

目的探讨用功能磁共振成像(fMRI)检测汉字情景记忆时皮层定位的价值及皮层定位的双侧不对称性.方法 10名健康右利手成人,以高频双字汉字作为刺激任务,行全脑fMRI,确定激活皮层的定位.结果汉字情景记忆时双侧多个脑区有激活,但两侧激活脑区不完全对称,编码加工时主要激活脑区为左侧纹外区和左侧颞叶梭状回,而提取加工时左侧顶叶楔前叶、左侧前额叶背外侧显著激活.结论汉字情景记忆时左右大脑半球激活区存在不对称性,fMRI可对此种功能皮层进行准确定位.     

静息态功能磁共振成像观察正常人听觉皮层功能

目的 探讨正常人听觉皮层与全脑的正相关及负相关的功能连接.方法 采用静息态下平面回波成像技术采集44名健康受试者fMRI数据,分别以左侧及右侧AⅠ区为种子点,用功能连接的方法观察左、右大脑初级听觉皮层与全脑的正相关及负相关功能连接脑图.结果 分别以双侧AⅠ区为种子点时,正激活的脑网络主要包含双侧AⅠ、AⅡ、岛叶、辅助运动区及扣带回,以同侧为主;与右侧AⅠ区相关的正激活脑区还包括同侧背侧丘脑.与双侧AⅠ区相关的负激活脑网络与脑默认网络大体一致,主要包括双侧后扣带回/楔前叶、额叶内侧回、顶下小叶,双侧小脑半球可见明显激活.结论 静息态磁共振功能连接可满意显示听觉皮层的连接脑图.正相关功能连接主要局限在听觉系统内,负相关功能连接类似于默认网络.     

脑缺血性卒中患者运动功能康复的功能性磁共振成像研究

目的利用功能性磁共振成像（fMRI）技术研究急性期缺血性脑卒中患者（以下简称急性期患者）运动相关皮质的激活情况，并探讨脑卒中后脑功能重组特点及其与肢体运动功能恢复的关系。方法采用GEI．5T双梯度16通道磁共振成像系统，对9例急性期患者和9例健康志愿者行Bold—fMRI检查。fMRI检查以被动对指运动（以下简称运动）为刺激任务，所有数据采用SPM2软件包进行离线后处理。比较健康志愿者与急性期患者fMRI结果的异同点，计算脑激活区体积和单侧化指数（LI），考察急性期患者患手运动LI值与患手运动功能的关系。结果健康志愿者单手运动激活对侧感觉运动皮质（SMC）、双侧辅助运动区（SMA）。急性期患者患手运动时同侧半球脑激话增多，健手运动的fMRI结果与健康志愿者基本一致。LI值也进一步确定，急性期患者患手运动时同侧半球脑激活增多。统计学分析表明，急性期患者患手运动的LI值与患手运动功能呈正相关。结论fMRI检查能客观地反映急性期患者运动相关皮质改变，提示存在脑功能代偿与重组。急性期患者患手运动LI值与患手运动功能呈正相关，提示fMRI是研究缺血性脑卒中后肢体运动功能康复与脑功能重组之间关系的一种有效工具。     

局灶性癫痫功能磁共振的语言重组与网络连接研究

目的:探讨局灶性癫痫患者的语言任务模式fMRI脑激活图,fMRI语言网络连接,分析语言功能与fMRI语言网络连接的联系.方法:选择18例符合诊断标准的局灶性癫痫患者(癫痫组)及18例健康志愿者(对照组),其中癫痫组完成以词语阅读任务为刺激模式的fMRI检查,以实现脑内相应功能区激活.利用SPM99软件进行分析,得出癫痫组与对照组fMRI的激活范围与信号变化,通过计算语言任务状态下fMRI最强激活区域时间过程相关性的信号变化,进行fMRI语言网络连接分析,采用独立样本t检验,比较癫痫组和对照组语言功能、fMRI语言网络连接的差异.结果:(1)局灶性癫痫患者fMRI语言激活图显示,激活强度和体积较健康组明显降低(P＜0.01),(2)在词语阅读任务刺激下,癫痫组与对照组最强激活区域相互间fMRI语言网络连接比较,差异具有非常显著性(P＜0.01).结论:局灶性癫痫损害患者的语言功能,癫痫患者语言fMRI激活强度、体积较对照组明显降低,且在最强激活区内,癫痫患者的fMRI语言网络连接明显低于对照组,同时结果显示癫痫患者之间的语言偏侧化不明显,局灶性癫痫患者语言功能的损害与fMRI语言网络连接减少密切相关.     

右侧正中神经电刺激促醒疗法对健康人脑功能影响的fMRI研究

目的 探讨右侧正中神经电刺激（RMNS）促醒疗法对健康人脑功能的影响。 方法 选取28例健康志愿者作为受试者，将RMNS促醒治疗模式作为任务刺激，采用Block实验设计，给予受试者30 s刺激-30 s休息共重复6次，并同步采用大脑功能磁共振成像(fMRI)技术进行成像扫描。使用SPM 12软件进行统计处理时将同一受试者刺激状态与静息状态的脑功能成像互为对照，分析其脑区激活情况。 结果 fMRI检查显示，RMNS促醒治疗模式下健康人脑正激活区主要集中在左侧初级运动皮质(M1)、皮质运动前区(PMC)，双侧初级体感皮质(S1）、双侧次级体感皮质(S2)及左侧岛叶。与静息态相比，RMNS促醒刺激模式下上述激活脑区BOLD信号强度变化较大，T>5.84，P<0.05（FWE校正）。 结论 右侧正中神经电刺激促醒治疗能通过激活右手运动及感觉功能相关脑区，兴奋局部大脑皮质，产生一定促醒效应。     

Reliability of fMRI for studies of language in post-stroke aphasia subjects

Quantifying change in brain activation patterns associated with post-stroke recovery and reorganization of language function over time requires accurate understanding of inter-scan and inter-subject variability. Here we report inter-scan variability measures for fMRI activation patterns associated with verb generation (VG) and semantic decision/tone decision (SDTD) tasks in 4 healthy controls and 4 aphasic left middle cerebral artery (LMCA) stroke subjects. A series of 10 fMRI scans was completed on a 4T Varian scanner for each task for each subject, except for one stroke subject who completed 5 and 6 scans for SDTD and VG, thus yielding 35 and 36 total stroke subject scans for SDTD and VG, respectively. Group composite and intraclass correlation coefficient (ICC) maps were computed across all subjects and trials for each task. The patterns of reliable activation for the VG and SDTD tasks correspond well to those regions typically activated by these tasks in healthy and aphasic subjects. ICCs for activation were consistently high (R(0.05) approximately 0.8) for individual tasks among both control and aphasic subjects. These voxel-wise measures of reliability highlight regions of low inter-scan variability within language circuitry for control and post-recovery stroke subjects. ICCs computed from the combination of the SDTD/VG data were markedly reduced for both control and aphasic subjects as compared with the ICCs for the individual tasks. These quantitative measures of inter-scan variability support the proposed use of these fMRI paradigms for longitudinal mapping of neural reorganization of language processing following left hemispheric insult.     

Age-related differences in movement representation

Repetitive movements have been used as motor activation tasks in the investigation of various neurological disorders. To determine the importance of an age-matched control group in such studies we investigated whether there are significant age-related changes in the pattern of cortical activation seen during simple repetitive movements. Sixteen right-handed healthy subjects were studied-8 young and 8 old. Functional magnetic resonance images were acquired while subjects performed a motor task or a nonmovement rest condition. Two continuous motor tasks, index finger abduction/adduction and wrist extension/flexion, were performed by each hand, paced using a metronome. The fMRI data were processed and analyzed with SPM '99. For the between-group comparisons, for each motor task, contralateral primary sensorimotor cortex and premotor cortex had significantly greater activation in the Young group and caudal supplementary motor area had significantly greater activation in the Old group. Ipsilateral sensorimotor cortex was more significantly activated in the Old group for index finger motor tasks of both hands. All noted differences in the Old group were more prominent for the index finger movement and most prominent when using the nondominant hand. In conclusion, there are significant age-related differences in the activation pattern associated with repetitive movements. This may represent compensatory recruitment of motor cortical units in the older subjects as larger differences are noted in the older group during the more difficult motor tasks, those of isolated finger movement and nondominant hand use. This study has important implications for functional imaging experiments of neurological disorders in older subjects.     

Cervical spinal cord BOLD fMRI study: modulation of functional activation by dexterity of dominant and non-dominant hands

The objective of this study was to investigate the effect of dexterity on the magnitude of signal changes in functional magnetic resonance imaging (fMRI) in the cervical spinal cord with unilateral finger-tapping. Right-handed healthy volunteers were investigated with blood oxygenation level-dependent (BOLD) fMRI. Spinal cord BOLD functional MR images were acquired from 10 healthy right-handed volunteers who performed four sessions of unilateral finger-tapping tasks: left sequential (LS), right sequential (RS), left interleaved (LI), and right interleaved (RI) tasks. Our results from the difficulty measurement test showed that finger-tapping in interleaved order was more difficult than in sequential order. For the functional activation, seven out of 10 subjects had activation in all four fMRI sessions (two of the subjects who showed no detectable activation had problems in volume registration). The mean contrast value of the activation area inside the entire cervical spinal cord was significantly higher in performing LS than RS tasks. The increase in the mean contrast value was because the less skilled and competent right hemisphere required additional processing power for doing the left hand task than the left hemisphere required in doing the right hand task. The analysis of the interleaved finger-tapping tasks did not show any significant difference in the results. This was probably because the interleaved task was similarly challenging for both hands, and required high dexterity. Therefore, differences in activity between the left and right hands were less apparent. Our results showed the modulation of activation intensity in the spinal cord by the dexterity.     

电刺激在痛觉功能磁共振成像研究中的应用

目的探讨直流脉冲电刺激在痛觉功能磁共振成像（fMRI）研究中的应用与价值。方法采用Medtronic全功能肌电图／诱发电位仪对10名健康右利手志愿者分别施加1倍痛阈、2倍痛阈、3倍痛阈三个不同强度的电刺激任务，同期采用GE1．5T超导型磁共振扫描系统进行全脑fMRI扫描，应用功能性神经图像分析（AFNI）软件包对原始数据进行后处理以获得脑功能图像。结果10名受试者的痛阈测定结果为1．17～2．12mA，平均痛阈强度为1．75mA。实验中所有受试者均顺利完成了各刺激任务，无受试者中途退出实验，数据处理后获得较为理想的脑功能激活图。结论电刺激对于诱发痛觉的强度、频率等各项参数能够达到精确量化，是一种较为理想的刺激方式，在痛觉的fMRI研究中具有重要的价值。     

fMRI evidence of brain reorganization during attention and memory tasks in multiple sclerosis

Functional magnetic resonance imaging (fMRI) data on motor function have shown adaptive functional changes related to brain injury in multiple sclerosis (MS). We investigated whether patients with MS have altered fMRI activation patterns during attention and memory tasks, and whether functional changes in the brain correlate with the extent of overall tissue damage on conventional MRI. Twenty-two right-handed patients with relapsing-remitting MS (RRMS) and no or only mild deficits at neuropsychological testing and 22 matched healthy subjects were scanned during the Paced Auditory Serial Addition Test (PASAT) and a recall task. fMRI data were analyzed using Statistical Parametric Mapping (SPM99). The relation between fMRI changes during both tasks and T2 lesion load was investigated. During both tasks, patients exhibited significantly greater brain activation than controls and recruited additional brain areas. Task-related functional changes were more significant in patients whose performance matched that of controls than in patients with a lower performance. During the PASAT, brain functional changes involved the right supplementary motor area and cingulate, the bilateral prefrontal, temporal and parietal areas, whereas during the recall task they involved the prefrontal and temporal cortex and basal ganglia bilaterally, and the left thalamus. In patients, activation in specific brain areas during performance of both tasks positively correlated with T2 brain lesions. Patients with RRMS exhibit altered patterns of activation during tasks exploring sustained attention, information processing and memory. During these tasks, fMRI activity is greater in patients with better cognitive function than in those with lower cognitive function. Functional changes in specific brain areas increase with increasing tissue damage suggesting that they may also represent adaptive mechanisms that reflect underlying neural disorganization or disinhibition, possibly associated with MS.     

Task-dependent posterior cingulate activation in mild cognitive impairment

Neuroimaging research has demonstrated that the posterior cingulate cortex (PCC) is functionally compromised in individuals diagnosed with amnestic mild cognitive impairment (MCI), a major risk factor for the development of Alzheimer's disease (AD). In functional MRI studies with healthy participants, this same region is active during self-appraisal (requiring retrieval of semantic knowledge about the self) as well as episodic recognition of previously learned information. Administering both types of tasks to people with MCI may reveal important information on the role of the PCC in recollection. This study investigated fMRI activation in the PCC in individuals with MCI and matched controls across two tasks. The first task was a visual episodic recognition task. The second task was an autobiographical self-appraisal task in which subjects rated themselves on a set of trait adjectives. Results of a conjunction analysis revealed the PCC as the sole region commonly active during both tasks in the healthy older adults. Furthermore, additional analysis revealed an interaction in the PCC, indicating a task-dependent response in the MCI group. MCI participants showed PCC activation during self-appraisal, but not episodic retrieval. This result suggests in MCI that the PCC shows functional degradation during episodic retrieval; however, the PCC's role in retrieval and evaluation of highly elaborated information regarding the self is more well-preserved.     

Right-hemispheric brain activation correlates to language performance

Language function in the right-hemispheric homologues of Broca's and Wernicke's areas does not only correlate with left-handedness or pathology, but occurs naturally in right-handed healthy subjects as well. In the current study, two non-invasive methods of assessing language lateralization are correlated with behavioral results in order to link hemispheric dominance to language ability in healthy subjects.Functional magnetic resonance imaging (fMRI) together with a sentence-completion paradigm was used to determine region-specific lateralization indices in the left- and right-sided Broca's and Wernicke's areas, the frontal temporal lobe, the anterior cingulate cortex and the parietal lobe. In addition, dichotic listening results were used to determine overall language lateralization and to strengthen conclusions by correlating with fMRI indices. Results showed that fMRI lateralization in the superior parietal, the posterior temporal, and the anterior cingulate cortices correlated to dichotic listening. A decreased right ear advantage (REA), which indicates less left-hemispheric dominance in language, correlated with higher performance in most administered language tasks, including reading, language ability, fluency, and non-word discrimination. Furthermore, right hemispheric involvement in the posterior temporal lobe and the homologue of Broca's area suggests better performance in behavioral language tasks. This strongly indicates a supportive role of the right-hemispheric counterparts of Broca's and Wernicke's areas in language performance.     

Pictures of a thousand words: investigating the neural mechanisms of reading with extremely rapid event-related fMRI

Reading is one of the most important skills human beings can acquire, but has proven difficult to study naturalistically using functional magnetic resonance imaging (fMRI). We introduce a novel Event-Related Reading (ERR) fMRI approach that enables reliable estimation of the neural correlates of single-word processing during reading of rapidly presented narrative text (200-300 ms/word). Application to an fMRI experiment in which subjects read coherent narratives and made no overt responses revealed widespread effects of orthographic, phonological, contextual, and semantic variables on brain activation. Word-level variables predicted activity in classical language areas as well as the inferotemporal visual word form area, specifically supporting a role for the latter in mapping visual forms onto articulatory or acoustic representations. Additional analyses demonstrated that ERR results replicate across experiments and predict reading comprehension. The ERR approach represents a powerful and extremely flexible new approach for studying reading and language behavior with fMRI.     

Dipole source localization and fMRI of simultaneously recorded data applied to somatosensory categorization

In this study, the feasibility of dipole source localization (DSL) and coregistration with functional magnetic resonance imaging (fMRI) activation patterns on the basis of simultaneously acquired data is demonstrated. Brain activity was mapped during the performance of a somatosensory single reaction and a choice reaction task at high spatiotemporal resolution in six healthy subjects. The choice reaction task required a categorization of two different stimulus intensities, whereas for the single reaction task merely the perception of a tactile stimulus had to be confirmed by the subjects. An offline artifact correction algorithm was applied to 32-channel EEG data that were acquired between subsequent MRI scans. Using a multiple dipole approach, five distinct dipole sources were identified within areas of the somatosensory system. Coregistration of fMRI and DSL showed consistent spatial activation patterns with a mean distance of 9.2 +/- 6.8 mm between dipole sources and fMRI activation maxima. However, since the number of fMRI activation sites exceeded the number of cerebral dipole sources, it was not possible to assign a dipole source to each fMRI activation site. Dipole moment time courses were consistent with previously reported results of similar experiments. A comparison of brain activation patterns during the two tasks with both fMRI and DSL indicated an involvement of the contralateral secondary somatosensory cortex in somatosensory categorization.     

Passive somatosensory discrimination tasks in healthy volunteers: differential networks involved in familiar versus unfamiliar shape and length discrimination

Somatosensory discrimination of unseen objects relies on processing of proprioceptive and tactile information to detect spatial features, such as shape or length, as acquired by exploratory finger movements. This ability can be impaired after stroke, because of somatosensory-motor deficits. Passive somatosensory discrimination tasks are therefore used in therapy to improve motor function. Whereas the neural correlates of active discrimination have been addressed repeatedly, little is known about the neural networks activated during passive discrimination of somatosensory information. In the present study, we applied functional magnetic resonance imaging (fMRI) while the right index finger of ten healthy subjects was passively moved along various shapes and lengths by an fMRI compatible robot. Comparing discriminating versus non-discriminating passive movements, we identified a bilateral parieto-frontal network, including the precuneus, superior parietal gyrus, rostral intraparietal sulcus, and supramarginal gyrus as well as the supplementary motor area (SMA), dorsal premotor (PMd), and ventral premotor (PMv) areas. Additionally, we compared the discrimination of different spatial features, i.e., discrimination of length versus familiar (rectangles or triangles) and unfamiliar geometric shapes (arbitrary quadrilaterals). Length discrimination activated mainly medially located superior parietal and PMd circuits whereas discrimination of familiar geometric shapes activated more laterally located inferior parietal and PMv regions. These differential parieto-frontal circuits provide new insights into the neural basis of extracting spatial features from somatosensory input and suggest that different passive discrimination tasks could be used for lesion-specific training following stroke.