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。     

人脑视觉皮质功能磁共振成像研究

目的研究人脑视觉皮质血氧水平依赖（BOLD）的功能磁共振成像。方法18名正常健康志愿者，在光刺激和非刺激的两种对比条件下，采用EP1技术，采集视觉皮质血氧水平依赖（BOLD）图像。t检验分析得出光刺激状态和非刺激状态信号对比的脑功能图像。结果fMRI图像显示光刺激下脑功能活动激活区主要位于双侧视觉皮质区。结论fMRI可用于在活体人脑上研究各功能区活动，光刺激下的fMRI可对人脑视觉皮质进行定位。     

人脑运动皮层功能磁共振成像研究

目的采用功能用磁共振成像（fMRI）回波平面（EPI）技术,研究人脑运动皮质血氧水平依赖（BOLD）的功能磁共振成像。方法27名正常健康志愿者,右手挤压橡皮圈,在运动和静止两种对比条件下,采集运动皮层的回波平面图像（BOLD-fMRI）。分析运动状态和非运动状态信号对比的脑功能图像。结果fMRI图像显示运动刺激下脑功能活动激活区主要位于对侧感觉运动皮质区、辅助运动区等。结论fMRI可用于研究活体人脑各功能区的活动,fMRI可对运动刺激下的人脑运动皮质进行初步定位。     

事件相关fMRI在重度抑郁症奖赏刺激反应中的研究进展

对奖赏刺激反应性减弱是重度抑郁症(MDD)的重要表现.功能性磁共振成像(fMRI)在抑郁症奖赏的脑影像学研究中发挥着重要作用.本文就事件相关fMRI在MDD奖赏刺激反应中的研究进行综述.     

海洛因成瘾者渴求任务对大型脑网络影响的功能磁共振研究

目的探讨海洛因成瘾者在毒品线索任务下主观渴求及大型脑网络特征。材料与方法 21例海洛因成瘾者与33例年龄、性别、教育程度相匹配的健康者,纳入该功能磁共振成像(functional MRI,fMRI)研究。应用Matlab、SPM8、DPABI及SPSS 20.0软件进行数据分析。首先,基于静息态fMRI的数据获取任务负相关网络及任务正相关网络;然后,进行事件相关毒品线索下的任务态fMRI,并对其大脑网络的差异行组间比较,继而与其心理行为学行相关性分析。结果海洛因成瘾者在毒品线索刺激任务后渴求程度显著性大于任务前(t=1.19,P=0.00);正常对照组此项对比无显著性差异(t=0.031,P=0.75)。与正常组相比,海洛因成瘾在毒品线索任务下,任务负相关网络(默认网络)及任务正相网络(突显网络、执行控制网络、高级视觉网络、视觉空间网络、基底核团)激活强度均显著增强(P<0.05,AphaSim校正),而任务正相关网络的初级视觉网络激活程度显著降低(P<0.05,AphaSim校正)。控制头动因素,海洛因成瘾者大脑基底核团激活强度与观看毒品相关线索后的渴求程度成正相关关系(r=0.56,P=0.01)。结论海洛因成瘾者心理渴求及在毒品线索条件下任务相关正、负大型脑网络功能均存在明显异常。     

电针刺激头皮感觉区联合感觉再训练治疗脑卒中感觉障碍的fMRI分析

目的 采用功能性磁共振成像(fMRI)观察电针刺激头皮感觉区联合感觉再训练对脑卒中患者感觉障碍的影响.方法 采用随机数字表法将40例脑卒中患者分为治疗组和对照组.2组患者均给予感觉再训练治疗,治疗组在此基础上辅以电针刺激头皮感觉区.于治疗前、治疗6周后采用Fugl-Meyer量表四肢感觉功能部分对2组患者偏瘫侧感觉功能进行评定;并于上述时间点对2组患者进行fMRI全脑扫描,在fMRI扫描期间2组患者均针刺患侧踝部(非穴位处)以获取针刺刺激时的脑功能激活图.结果 2组患者分别经6周治疗后,发现其感觉功能均较治疗前明显改善(P＜0.05),其中治疗组感觉功能评分[(16.52±2.31)分]明显优于对照组水平[(12.21±2.42)分](P＜0.05);通过fMRI扫描发现,治疗组患者治疗后其患侧感觉运动皮质区(SMG)激活出现率(80.0％)明显高于对照组(50.0％),组间差异具有统计学意义(P＜0.05).结论 电针刺激头皮感觉区联合感觉再训练能促进脑卒中患者躯干感觉皮质及大脑感觉皮质兴奋性改变,提示fMRI对研究电针刺激头皮感觉区的作用机制具有重要价值.     

人脑运动皮质对针刺足三里和阳陵泉反应的功能性磁共振成像研究

目的利用功能性磁共振成像(fMRI)技术观察人脑运动皮质对针刺足三里和阳陵泉穴的反应,对针刺神经机制进行初步探讨.方法对20名健康志愿者(正常对照组)和17例左侧中央沟区病变导致运动障碍的患者(运动障碍组)行实时动态fMRI检查.每名志愿者分别接受以下两项任务①右手对指运动,②被针刺右侧足三里和阳陵泉.对激活的运动皮质功能区进行计数.采用SAS软件包作精确概率法比较两项任务激活各运动功能区的概率.运动障碍组均接受针刺任务,观察病变周围fMRI信号变化情况.结果在正常对照组对指任务时,除去1例合作不好外,其余19例激活右侧第一运动皮质区(RMI)8例,右侧运动前区(RPMC)8例,副运动区(SMA)9例,左侧第一运动皮质区(LMI)19例,左侧运动前区(LPMC)9例针刺任务时,除去4例运动图像伪影明显外,其余16例激活RMI 7例,RPMC11例,SMA 9例,LMI11例,LPMC 13例.对指运动激活LMI概率(100%)较针刺(68.75%)高(P<0.05);其余各运动功能区激活概率差异无显著性(P>0.05).运动障碍组接受针刺任务时,在fMRI脑功能图的整个上额叶均可见明显的功能激活区.结论 fMRI证实运动皮质对针刺足三里和阳陵泉穴存在广泛的反应,人脑的这种反应可能为针刺效应的重要机制.磁共振脑功能成像在针刺机制的研究方面具有重要价值.     

人类大脑皮层对人物肖像和风景识别的fMRI研究

目的探讨人类大脑对物体的识别功能区集中在大脑皮层的位置.方法使用了三种黑白图片:人物肖像、自然风景和打乱的图片给9例均为右利手的正常人观看,同时用1.5 T MRI仪采集实验对象的解剖像、三维全脑结构像和功能像.实验结果用功能神经成像分析软件 (AFNI)进行数据处理及分析.结果在腹侧颞叶(梭状回)后部存在两个相邻的区域分别对风景和人物敏感,其中靠内侧的区域对风景刺激的反应更强烈,靠外侧的区域则对人物刺激的反应更强;而且风景相关区域和人物相关区域呈现出从内侧到外侧的一种渐变过渡的分布.结论尽管参与人物视觉加工的脑区和参与风景视觉加工的脑区对不同的两种刺激的反应强度有所不同,但两个脑区并不截然分开,而是连续分布并相互重叠的.     

咖啡因对抗睡眠剥夺影响执行控制功能的fMRI研究

目的 研究36 h睡眠剥夺(SD)以及睡眠剥夺并服用咖啡因后脑部功能磁共振成像(fMRI)特点,探讨咖啡因对抗睡眠剥夺对大脑功能影响的可能机制.方法 13名健康男性大学生参加试验.试验采用随机、双盲自身对照设计,对受试者在清醒状态下以及36 h睡眠剥夺并随机服用咖啡因或者安慰剂后进行Go/No-go测验并使用3.0T磁共振仪进行fMRI扫描,3次fMRI扫描之间间隔3周.受试者行为学数据使用SPSS软件处理,fMRI数据使用AFNI软件包进行处理.结果 36 h睡眠剥夺后受试者前额叶皮层显著激活,前扣带回功能活动下降;服用咖啡因后双侧豆状核、丘脑、边缘系统相关脑区激活程度下降.结论 36 h睡眠剥夺可导致执行控制功能的显著下降,前额叶皮质参与功能代偿.咖啡因通过对边缘系统相关区域及纹状体系统活动的抑制来对抗睡眠剥夺对于执行控制功能的影响.     

脑功能活动磁共振成像与经络-中枢神经相关学说

脑功能活动磁共振成像 (ｆＭＲｌ)是磁共振成像的一种应用和深入发展 ,主要用磁共振成像的方法研究人脑和神经系统的功能。 1990年对动物的实验表明有可能用磁共振成像研究大脑功能 ,1991年发表了第一幅有意义的人大脑功能图像 ,显示出视觉刺激在大脑的反应[1] ,开始了脑功能活     

Measuring interregional functional connectivity using coherence and partial coherence analyses of fMRI data

Understanding functional connectivity within the brain is crucial to understanding neural function; even the simplest cognitive operations are supported by highly distributed neural circuits. We developed a novel method to measure task-related functional interactions between neural regions by applying coherence and partial coherence analyses to functional magnetic resonance imaging (fMRI) data. Coherence and partial coherence are spectral measures that estimate the linear time-invariant (LTI) relationship between time series. They can be used to generate maps of task-specific connectivity associated with seed regions of interest (ROIs). These maps may then be compared across tasks, revealing nodes with task-related changes of connectivity to the seed ROI. To validate the method, we applied it to an event-related fMRI data set acquired while subjects performed two sequence tapping tasks, one of which required more bimanual coordination. Areas showing increased functional connectivity with both tasks were the same as those showing increased activity. Furthermore, though there were no significant differences in mean activity between the two tasks, significant increases in interhemispheric coherence were found between the primary motor (M1) and premotor (PM) regions for the task requiring more bimanual coordination. This increase in interhemispheric connectivity is supported by other brain imaging techniques as well as patient studies.     

Visual analytics of brain networks

Identification of regions of interest (ROIs) is a fundamental issue in brain network construction and analysis. Recent studies demonstrate that multimodal neuroimaging approaches and joint analysis strategies are crucial for accurate, reliable and individualized identification of brain ROIs. In this paper, we present a novel approach of visual analytics and its open-source software for ROI definition and brain network construction. By combining neuroscience knowledge and computational intelligence capabilities, visual analytics can generate accurate, reliable and individualized ROIs for brain networks via joint modeling of multimodal neuroimaging data and an intuitive and real-time visual analytics interface. Furthermore, it can be used as a functional ROI optimization and prediction solution when fMRI data is unavailable or inadequate. We have applied this approach to an operation span working memory fMRI/DTI dataset, a schizophrenia DTI/resting state fMRI (R-fMRI) dataset, and a mild cognitive impairment DTI/R-fMRI dataset, in order to demonstrate the effectiveness of visual analytics. Our experimental results are encouraging.     

Relation of dietary restraint scores to activation of reward-related brain regions in response to food intake, anticipated intake, and food pictures

Prospective studies indicate that individuals with elevated dietary restraint scores are at increased risk for future bulimic symptom onset, suggesting that these individuals may show hyper-responsivity of reward regions to food and food cues. Thus, we used functional magnetic resonance imaging (fMRI) to examine the relation of dietary restraint scores to activation of reward-related brain regions in response to receipt and anticipated receipt of chocolate milkshake and exposure to pictures of appetizing foods in 39 female adolescents (mean age=15.5 ± 0.94). Dietary restraint scores were positively correlated with activation in the right orbitofrontal cortex (OFC) and bilateral dorsolateral prefrontal cortex (DLPFC) in response to milkshake receipt. However, dietary restraint scores did not correlate with activation in response to anticipated milkshake receipt or exposure to food pictures. Results indicate that individuals who report high dietary restraint have a hyper-responsivity in reward-related brain regions when food intake is occurring, which may increase risk for overeating and binge eating.     

fMRI reactivity to high-calorie food pictures predicts short- and long-term outcome in a weight-loss program

Behavioral studies have suggested that food cues have stronger motivating effects in obese than in normal-weight individuals, which may be a risk factor underlying obesity. Previous cross-sectional neuroimaging studies have suggested that this difference is mediated by increased reactivity to food cues in parts of the reward system in obese individuals. To date, however, only a few prospective neuroimaging studies have been conducted to examine whether individual differences in brain activation elicited by food cues can predict differences in weight change. We used functional magnetic resonance imaging (fMRI) to investigate activation in reward-system as well as other brain regions in response to viewing high-calorie food vs. control pictures in 25 obese individuals before and after a 12-week psychosocial weight-loss treatment and at 9-mo follow-up. In those obese individuals who were least successful in losing weight during the treatment, we found greater pre-treatment activation to high-calorie food vs. control pictures in brain regions implicated in reward-system processes, such as the nucleus accumbens, anterior cingulate, and insula. We found similar correlations with weight loss in brain regions implicated by other studies in vision and attention, such as superior occipital cortex, inferior and superior parietal lobule, and prefrontal cortex. Furthermore, less successful weight maintenance at 9-mo follow-up was predicted by greater post-treatment activation in such brain regions as insula, ventral tegmental area, putamen, and fusiform gyrus. In summary, we found that greater activation in brain regions mediating motivational and attentional salience of food cues in obese individuals at the start of a weight-loss program was predictive of less success in the program and that such activation following the program predicted poorer weight control over a 9-mo follow-up period.     

Subjective feeling of appetite modulates brain activity: an fMRI study

Obesity and overweight are important risk factors for the development of diabetes mellitus type 2 and associated chronic diseases, and therefore, they have become serious global problems in the western and developed countries. But little is known about the neuroanatomical correlates of eating behavior and its influences on the central nervous processing in humans. We used functional magnetic resonance imaging (fMRI) to measure the cortical activation in 12 lean healthy humans during visual stimulation with food-related and nonfood pictures after a fasting period of at least 5 h. Compared to the nonfood pictures, the food stimuli elicited a significantly greater activity in the left orbitofrontal cortex and the insular/opercular cortex bilaterally with a stronger focus on the left side. Subjective ratings of appetite during the presentation of food-related stimuli modulated the activity in the insula bilaterally, the left operculum and the right putamen. These results provide further insights in the central nervous processing of food relevant stimuli in humans, specifically with respect to the subjective experience of appetite.     

Art for reward's sake: visual art recruits the ventral striatum

A recent study showed that people evaluate products more positively when they are physically associated with art images than similar non-art images. Neuroimaging studies of visual art have investigated artistic style and esthetic preference but not brain responses attributable specifically to the artistic status of images. Here we tested the hypothesis that the artistic status of images engages reward circuitry, using event-related functional magnetic resonance imaging (fMRI) during viewing of art and non-art images matched for content. Subjects made animacy judgments in response to each image. Relative to non-art images, art images activated, on both subject- and item-wise analyses, reward-related regions: the ventral striatum, hypothalamus and orbitofrontal cortex. Neither response times nor ratings of familiarity or esthetic preference for art images correlated significantly with activity that was selective for art images, suggesting that these variables were not responsible for the art-selective activations. Investigation of effective connectivity, using time-varying, wavelet-based, correlation-purged Granger causality analyses, further showed that the ventral striatum was driven by visual cortical regions when viewing art images but not non-art images, and was not driven by regions that correlated with esthetic preference for either art or non-art images. These findings are consistent with our hypothesis, leading us to propose that the appeal of visual art involves activation of reward circuitry based on artistic status alone and independently of its hedonic value.     

Improvement of fMRI data processing of olfactory responses with a perception-based template

Neuroimaging and in particular functional magnetic resonance imaging (fMRI) of olfactory function relies on the ability to model the time course of brain responses elicited by odor stimuli. In this study we compared two templates of olfactory brain activation by comparing levels of correlation in regions critical to olfactory processing with either a stimulation-based template or a perception-based template, derived from perception profiles acquired off-line during a simulated fMRI session. fMRI signal was more correlated with the perception-based template than with the stimulation-based template in all regions. This effect was not observed when comparing correlations obtained with the exact same templates shifted in time by 12 s. Therefore, the improvement due to the use of the perception-based template was not only caused by a difference of shape between the stimulation-based and the perception-based template but was specifically related to the olfactory stimulation performed. These results suggest that the perception-based template better represents brain activity in response to olfactory stimulation and might help improve data processing of fMRI studies investigating olfactory function.     

The single-epoch fMRI design: validation of a simplified paradigm for the collection of subjective ratings

One of the goals of human functional imaging studies is to interpret brain activation in the context of an individual's subjective experience. However, functional magnetic resonance imaging (fMRI) studies usually employ a block design that consists of multiple epochs of stimulation; this strategy does not readily allow subjective responses to be assessed on a stimulus-by-stimulus basis. To address this issue, we developed a "single-epoch" design, consisting of a single stimulation period presented between two baseline periods. This allows subjective ratings to be acquired after each stimulus, while minimizing rating-induced confounds. To evaluate its sensitivity and utility, we obtained fMRI data using single-epoch and block designs (five stimuli between six baselines) and assessed regional brain activations evoked by both visual (a checkerboard pattern) and painful (noxious heat to right calf) stimuli. For both types of stimulation, data collected using the single-epoch design displayed activation patterns that were generally similar to those detected with the block design. Furthermore, only one single-epoch acquisition series was sufficient to detect bilateral activation in the visual cortex during visual stimulation and activation in the primary somatosensory cortex, the anterior cingulate cortex, and other regions during painful stimulation. In addition, analyses of a series of single-epoch data from a single individual revealed a stimulus-by-stimulus decrease in the activation in the anterior cingulate cortex that paralleled the decrease in the subject's psychophysical responses. These findings confirm that the single-epoch design is sensitive to regional signal changes and serves as a viable alternative to the block design when the collection of subjective responses is of critical importance.     

Cortical mechanisms of visual self-recognition

Several lines of evidence have suggested that visual self-recognition is supported by a special brain mechanism; however, its functional anatomy is of great controversy. We performed an event-related functional magnetic resonance imaging (fMRI) study to identify brain regions selectively involved in recognition of one's own face. We presented pictures of each subject's own face (SELF) and a prelearned face of an unfamiliar person (CONT), as well as two personally familiar faces with high and low familiarity (HIGH and LOW, respectively) to test selectivity of activation to the SELF face. Compared with the CONT face, activation selective to the SELF face was observed in the right occipito-temporo-parietal junction and frontal operculum, as well as in the left fusiform gyrus. On the contrary, the temporoparietal junction in both the hemispheres and the left anterior temporal cortex, which were activated during recognition of HIGH and/or LOW faces, were not activated during recognition of the SELF face. The results confirmed the partial distinction of the brain mechanism involved in recognition of personally familiar faces and that in recognition of one's own face. The right occipito-temporo-parietal junction and frontal operculum appear to compose a network processing motion-action contingency, a role of which in visual self-recognition has been suggested in previous behavioral studies. Activation of the left fusiform gyrus selective to one's own face was consistent with the results of two previous functional imaging studies and a neuropsychological report, possibly suggesting its relationship with lexical processing.