Data-based functional template for sorting independent components of fMRI activity

In human brain imaging with naturalistic stimuli, hemodynamic responses are difficult to predict and thus data-driven approaches, such as independent component analysis (ICA), may be beneficial. Here we propose inter-subject correlation (ISC) maps as stimulus-sensitive functional templates for sorting the independent components (ICs) to identify the most stimulus-related networks without stimulus-dependent temporal covariates. We collected 3-T functional magnetic resonance imaging (fMRI) data during perception of continuous audiovisual speech. Ten adults viewed a video, in which speech intelligibility was varied by altering the sound level. Five ICs with strongest overlap with the ISC map comprised auditory and visual cortices, and the sixth was a left-hemisphere-dominant network (left posterior superior temporal sulcus, inferior frontal gyrus, anterior superior temporal pole, supplementary motor cortex, and right angular gyrus) that was activated stronger during soft than loud speech. Corresponding temporal-model-based analysis revealed only temporal- and parietal-lobe activations without involvement of the anterior areas. The performance of the ISC-based IC selection was confirmed with fMRI data collected during free viewing of movie. Since ISC-ICA requires no predetermined temporal models on stimulus timing, it seems feasible for fMRI studies where hemodynamic variations are difficult to model because of the complex temporal structure of the naturalistic stimulation.     

Reversed lateralization of temporal activation during speech production in thought disordered patients with schizophrenia

BACKGROUND: Formal thought disorder is a core symptom of schizophrenia. It is associated with a reversed lateralization of the superior temporal cortex volume, an area that is implicated in lexical retrieval. We investigated the neural correlates of word retrieval during continuous speech in patients with formal thought disorder using functional magnetic resonance imaging (fMRI). METHODS: Blood oxygenation level dependent (BOLD) contrast was measured with fMRI while six patients with schizophrenia and six healthy control subjects spoke about seven Rorschach inkblots for 3 min each. Subjects produced varying amounts of speech during each run. In a within subject design, the number of words produced was correlated with the BOLD contrast in the two runs in each participant who showed the highest variance of speech output. RESULTS: In control subjects, the amount of speech produced was mainly correlated with activation in the left superior temporal gyrus. In the patient group, the main correlations were in the right superior temporal gyrus. CONCLUSIONS: During the production of continuous speech, patients with formal thought disorder showed a reversed laterality of activation in the superior temporal cortex. This is consistent with findings of perturbed hemispheric interaction in schizophrenia, particularly in patients with formal thought disorder.     

Independent neural control of rhythmic sequences--behavioral and fMRI evidence

Can the temporal structure of movement sequences can be represented and learned independently of their ordinal structure? Are some brain regions particularly important for temporal sequence performance? We addressed these questions in behavioral and functional magnetic resonance imaging (fMRI) experiments. Using a learning transfer design, we found evidence for independent temporal representations: learning a spatiotemporal sequence facilitated learning its temporal and ordinal structure alone; learning a temporal and an ordinal structure facilitated learning of a sequence where the two were coupled. Secondly, learning of temporal structures was found during reproduction of sequential stimuli with random ordinal structure, suggesting independent mechanisms for temporal learning. We then used fMRI to investigate the neural control of sequences during well-learned performance. The temporal and ordinal structure of the sequences were varied in a 2x2 factorial design. A dissociation was found between brain regions involved in ordinal and temporal control, the latter mainly involving the pre-supplementary motor area, the inferior frontal gyrus, the precentral sulcus, and the superior temporal gyri. In a second fMRI experiment, temporal sequences were performed with the left or right index fingers, or using rhythmic speech. The overlap in brain activity during performance with the different effectors included a similar set of brain regions to that found in the first fMRI experiment: the supplementary motor area and the superior temporal and inferior frontal cortices. We suggest that these regions are important for abstract, movement-independent temporal sequence control. This organization may be important for flexibility in voluntarily timed motor tasks.     

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。     

Analysis of fMRI data by blind separation of data in a tiny spatial domain into independent temporal component

Independent Component Analysis (ICA) is a promising tool for the analysis of functional magnetic resonance imaging (fMRI) time series. In these studies, mostly assumed is a spatially independent component map of fMRI data (spatial ICA). In this paper, we assume that the temporal courses of the signal and noises are independent within a Tiny spatial domain (temporal ICA). Then with fast-ICA algorithm, spatially neighboring fMRI data were blindly separated into several temporal courses and were preassumed to be formed by a signal time course and several noise time courses where the signal has the largest correlation coefficient with the reference signal. The final functional imaging was completed for the signals obtained from each voxel. Simulations showed that compared with the spatial ICA method, the new temporal ICA method is more effective than the spatial ICA in detecting weak signal in a fMRI dataset. As background noise, the simulations include simulated Gaussian noise and fMRI data without stimulation. Finally, vivo fMRI tests showed that the excited areas evoked by a visual stimuli are mainly in the region of the primary visual cortex and that evoked by auditory stimuli are mainly in the region of the primary temporal cortex.     

2型糖尿病患者功能磁共振成像的局部脑区活动时空四维一致性

目的:利用功能磁共振成像（fMRI）及临床资料研究2型糖尿病（T2D）患者脑功能及血糖指标改变状况。方法:采集T2D患者（34例）及健康被试（37例）的fMRI信号,计算局部脑区神经活动时空四维一致性指标（FOCA）,采集被试者临床实验室检查信息,并分析二者的相关性。结果:与健康对照组相比,T2D患者的FOCA值在左侧颞中回、右侧颞上回显著降低,在右侧小脑显著增加。左侧颞中回的FOCA值与空腹血糖指标、餐后血糖指标呈现显著的负相关。结论:T2D患者会出现右侧小脑、右侧颞上回、左侧颞中回等脑区自发神经活动的紊乱,且左侧颞中回的活动异常与T2D患者空腹及餐后2 h血糖水平等指标具有相关性。     

Event related fMRI studies of voluntary and inhibited eye blinking using a time marker of EOG

Electrooculogram (EOG) measurements, along with infrared measurements, are commonly used to record eye blinking during functional magnetic resonance imaging (fMRI). We report herein, on the use of EOG in measuring voluntary and inhibited eye blinking during echo planar imaging (EPI) in an MR scanner. The inhibited eye blinking occurred during the period, in which subjects were requested not to blink their eyes. After the removal of gradient-field induced artifacts from the EOG signal, the waveform of the EOG clearly showed both voluntary and inhibited eye blinking. Using these data, each voluntary or inhibited eye-blinking event was used as the temporal cue for an event related fMRI. Activation of the bilateral parahippocampal, precentral gyrus and left supplementary motor area was observed for voluntary eye blinking, whereas the medial/superior frontal, precentral, cingulate, precuneus, and superior temporal gyrus appears to be involved in inhibited eye blinking. Based on these experimental results, we propose that the precentral gyrus is responsible for both voluntary and inhibited eye blinking. The parietal area (precuneus and superior temporal gyrus) appears to be exclusively related to inhibited eye blinking.     

新的独立成分分析算法结合主成分分析实现fMRI信号的盲分离

用ICA算法来实现fMRI信号的盲源分离,可以提取出产生fMRI信号的多种源信号。但是在处理过程中存在两个困难:(1)fMRI数据的规模比较大,计算耗时;(2)计算量太大难免产生误差,给结果的分析带来不便。所以我们考虑对数据进行降维,但是如何确定源信号的个数也是一个难题。我们利用信息论的方法来估计源信号的个数,再使用主成分分析对数据进行降维。通过这样的处理,有效地确定了源信号的个数,减少了计算量。然后将一种新的ICA算法(New fixed-point,NewFP)用于处理降维后的数据。最后通过对实际的fMRI信号进行处理,结果表明新算法可以快速有效的分离fMRI信号,且准确性优于FastICA算法。     

男性攻击性精神分裂症患者杏仁核功能连接的磁共振研究

目的:探讨男性攻击性精神分裂症患者是否存在杏仁核与其他脑区功能连接的异常.方法:对有攻击行为和没有攻击行为的男性精神分裂症患者各13例进行静息状态下功能磁共振成像.结果:与非攻击组相比,攻击组双侧额中回、右侧额上回、右侧脑岛、右侧顶上小叶、右侧扣带回等脑区与左侧杏仁核功能连接增强;双侧额上回、额中回、双侧颞上回、右侧颢中回等脑区与右侧杏仁核功能增强.结论:杏仁核与多个脑区之间特别是与额上回、额中回的功能连接增强可能与男性精神分裂症患者的攻击行为有关.     

动态表情情绪识别相关脑区的fMRI研究

目的:利用事件相关的功能核磁共振成像技术研究健康汉族女性对动态表情的识别情况并探讨其神经基础。方法:利用1.5T功能核磁共振成像系统检测13名女性健康受试者识别悲伤、喜悦及中性动态表情视频时的脑部反应。图像数据经SPM2软件处理和统计分析,获得脑区激活图。结果:与识别十字架相比,识别中性表情激活左额中回、双侧中央前回、右侧杏仁核、左顶下小叶、右中央后回以及丘脑等。与识别中性表情相比,识别喜悦表情激活右额内侧回、右额上回、右额中回、右前扣带回、左胼胝体下回、右枕上回、右枕下回、左枕中回及右颞上回等脑区,而识别悲伤表情激活左额内侧回、右额中回、左颞下回以及左颞上回等脑区。结论:面孔加工及动态表情的识别由脑内一个分布式神经网络所调控,其中额内侧回参与多种情绪的加工,可能是情绪加工的共同通路,而颞上回主要负责面部动态特征的加工。     

Investigating human audio-visual object perception with a combination of hypothesis-generating and hypothesis-testing fMRI analysis tools

Primate multisensory object perception involves distributed brain regions. To investigate the network character of these regions of the human brain, we applied data-driven group spatial independent component analysis (ICA) to a functional magnetic resonance imaging (fMRI) data set acquired during a passive audio-visual (AV) experiment with common object stimuli. We labeled three group-level independent component (IC) maps as auditory (A), visual (V), and AV, based on their spatial layouts and activation time courses. The overlap between these IC maps served as definition of a distributed network of multisensory candidate regions including superior temporal, ventral occipito-temporal, posterior parietal and prefrontal regions. During an independent second fMRI experiment, we explicitly tested their involvement in AV integration. Activations in nine out of these twelve regions met the max-criterion (A??V) for multisensory integration. Comparison of this approach with a general linear model-based region-of-interest definition revealed its complementary value for multisensory neuroimaging. In conclusion, we estimated functional networks of uni- and multisensory functional connectivity from one dataset and validated their functional roles in an independent dataset. These findings demonstrate the particular value of ICA for multisensory neuroimaging research and using independent datasets to test hypotheses generated from a data-driven analysis.     

原发性失眠患者大脑背外侧前额叶的异常静息态功能连接

目的:利用功能连接方法观察原发性失眠患者静息态下的背外侧前额叶的异常功能连接。方法:采集33 例原 发性失眠患者以及33 例年龄、性别和受教育程度相匹配的健康对照的功能磁共振图像,以背外侧前额叶为感兴趣区 域,与全脑其他体素进行功能连接分析,得到两组之间功能连接的差异脑区,再对异常功能连接脑区与临床的量表分 数做相关分析。结果:与对照组相比,发现失眠患者左侧背外侧前额叶与左侧枕下回、右侧枕下回、右侧枕中回、右侧 颞叶、左侧额中回,左侧额下回以及右侧梭状回之间的功能连接增强（P<0.05,体素簇个数≥100,FDR校正）,与左侧前 扣带皮层、右侧海马旁回、右侧脑岛、右侧背外侧额上回、右侧顶上回、右侧中央后回以及右侧中央前回之间的功能连 接减弱（P<0.05,体素簇个数≥100,FDR校正）。并且左侧背外侧前额叶与左侧枕叶下回的功能连接值与睡眠状况自评 量表分数成正相关（P=0.035）。结论:原发性失眠患者背外侧前额叶与大脑多个脑区出现异常的功能连接,可能为理 解原发性失眠患者的神经机制提供一些新的影像学依据。     

Localization of Latent Epileptic Activities Using Spatio-Temporal Independent Component Analysis of fMRI Data

Summary Localizing interictal epileptic activities is a difficult problem in clinical practice. We report a novel noninvasive technique, resting functional magnetic resonance imaging (fMRI) with spatio-temporal independent component analysis (ICA), for localizing interictal epileptic activities. First, the fMRI data is separated into independent spatial patterns by spatial-ICA, and the patterns with Z-values larger than a threshold are selected as the potential spatial patterns of the epileptic activities. Second, the temporal series of the active points in the selected patterns are separated by temporal-ICA, and the component with the biggest Gaussian deviation (kurtosis) is selected as the representative of the epileptic discharge activity in a sub-region. Finally, those spatial sub-regions, which have distinct epileptic discharge activities confirmed by temporal–ICA are considered as the epileptic foci. This method was applied to fMRI data of six epileptic patients, and the results are consistent with the clinical assessment. Though more studies are required to validate this technique, the above preliminary results demonstrate the potential of using the resting fMRI with spatio-temporal ICA to detect and localize latent epileptic activities. An erratum to this article can be found at     

Negative BOLD during tongue movement: A functional magnetic resonance imaging study

The aim of this functional magnetic resonance imaging (fMRI) study was to evaluate negative blood oxygen level-dependent (BOLD) signals during voluntary tongue movement. Deactivated (Negative BOLD) regions included the posterior parietal cortex (PPC), precuneus, and middle temporal gyrus. Activated (Positive BOLD) regions included the primary somatosensory-motor area (SMI), inferior parietal lobule, medial frontal gyrus, superior temporal gyrus, insula, lentiform nucleus, and thalamus. The results were not consistent with previous studies involving unilateral hand and finger movements showing the deactivation of motor-related cortical areas including the ipsilateral MI. The areas of Negative BOLD in the PPC and precuneus might reflect specific neural networks relating to voluntary tongue movement.     

慢性创伤后应激障碍患者对短期记忆提取任务的脑功能磁共振研究

目的:探讨慢性创伤后应激障碍(post-traumatic stress disorder,PTSD)患者执行短期记忆提取任务时脑功能的激活特征。方法:对17例矿难相关的慢性PTSD患者和14例经历相同矿难未患病的对照进行脑功能磁共振成像。结果:与对照组比,病例组左海马旁回,右颞上回,左中央后回,右角回,右豆状核的激活降低。结论:慢性PTSD患者存在短期记忆受损的情况。颞叶(包括边缘系统),顶叶,杏仁核可能参与了短时记忆贮存与提取的过程。     

Combining electrophysiological and hemodynamic measures of the auditory oddball

The neural mechanisms of deviancy and target detection were investigated by combining high density event-related potential (ERP) recordings with functional magnetic resonance imaging (fMRI). ERP and fMRI responses were recorded using the same paradigm and the same subjects. Unattended deviants elicited a mismatch negativity (MMN) in the ERP. In the fMRI data, activations of transverse/superior temporal gyri bilateral were found. Attended deviants generated an MMN followed by an N2/P3b complex. For this condition, fMRI activations in both superior temporal gyri and the neostriatum were found. These activations were taken as neuroanatomical constraints for the localization of equivalent current dipoles. Inverse solutions for dipole orientation provide evidence for significant activation close to Heschl's gyri during deviancy processing in the 110-160-ms time interval (MMN), whereas target detection could be modeled by two dipoles in the superior temporal gyrus between 320 and 380 ms.     

基于低频振幅算法的屈光参差性弱视自发脑活动研究

目的基于低频振幅(amplitude of low frequency fluctuation,ALFF)算法分析屈光参差性弱视和正常对照组的功能性磁共振成像(functional magnetic resonance imaging,f MRI)图像数据,对比揭示弱视患者脑部自发活动的异常,以及这些异常与弱视视力损失的相关性。方法在闭眼静息条件下采集22例弱视成年人和21例正常对照组f MRI数据,对f MRI数据进行预处理,计算每个被试脑区的ALFF值。应用双样本t检验对ALFF结果进行组间分析,采用皮尔森分析弱视不同脑区的ALFF与其损伤的相关程度。结果在屈光参差性成人弱视与正常组有显著性差异的脑区中,脑部自发活动增加的脑区主要分布在颞下回、颞上回、枕叶等区域,脑部自发活动降低的脑区主要分别在小脑后叶、额下回、额上回等区域。首次发现小脑后叶、楔回、枕叶、颞上回和额叶等区域脑区自发活动与弱视损伤有显著相关性。结论基于低频振幅的静息态磁共振分析是有效的非侵入式脑区同步性异常研究方法,能够反映屈光参差性弱视自发脑部活动脑区异常表现,这些同步性异常表现与视力损失程度有较强的相关性,这些结果对于弱视致病机制模型研究和提出新的治疗方法都有重要启发。     

Neural sources involved in auditory target detection and novelty processing: an event-related fMRI study

We used event-related functional magnetic resonance imaging (erfMRI) techniques to examine the cerebral sites involved with target detection and novelty processing of auditory stimuli. Consistent with the results from a recent erfMRI study in the visual modality, target processing was associated with activation bilaterally in the anterior superior temporal gyrus, inferior and middle frontal gyrus, inferior and superior parietal lobules, anterior and posterior cingulate, thalamus, caudate, and the amygdala/hippocampal complex. Analyses of the novel stimuli revealed activation bilaterally in the inferior frontal gyrus, insula, inferior parietal lobule, and in the inferior, middle, and superior temporal gyri. These data suggest that the scalp recorded event-related potentials (e.g., N2 and P3) elicited during similar tasks reflect an ensemble of neural generators located in spatially remote cortical areas.     

Neural correlates of pre-performance routines in expert and novice archers

The objective of the present study was to determine differences in neural networks between expert and novice archers during an archery pre-performance routine period (PPR). The experiment was conducted with eight world-class competitor or Olympic medalist archers and eight novices. In the experiment, the task was to shoot (by clicking a mouse with the right hand) if an archery target appeared on an LCD embedded in an functional magnetic resonance imaging (fMRI) scanner. The resultant fMRI data showed that when the experts were aiming, the occipital gyrus and temporal gyrus were activated, but when the novices were aiming, the frontal area was mainly activated. In addition, the anterior cingulate and posterior cingulate gyrus of the limbic lobe were also activated in the expert and novice groups, respectively. Our results demonstrated that expert and novice archers differed in levels of brain activation during the PPR period of a simulated archery task.