Involvement of right piriform cortex in olfactory familiarity judgments

Previous studies have shown activation of right orbitofrontal cortex during judgments of odor familiarity. In the present study, we sought to extend our knowledge about the neural circuits involved in such a task by exploring the involvement of the right prefrontal areas and limbic/primary olfactory structures. Fourteen right-handed male subjects were tested using fMRI with a single functional run of two olfactory conditions (odor detection and familiarity judgments). Each condition included three epochs. During the familiarity condition, subjects rated whether odors were familiar or unfamiliar. During the detection condition, participants decided if odors were present. When contrasting the familiarity with the detection conditions, activated areas were found mainly in the right piriform cortex (PC) and hippocampus, the left inferior frontal gyrus and amygdala, and bilaterally in the mid-fusiform gyrus. Further analyses demonstrated that the right PC was more strongly activated than the left PC. This result supports the notion that the right PC is preferentially involved in judgments of odor familiarity.     

Left temporo-limbic and orbital dysfunction in schizophrenia during odor familiarity and hedonicity judgments

Impairments of olfactory processing in patients with schizophrenia (SZ) have been reported in various olfactory tasks such as detection, discrimination, recognition memory, identification, and naming. The purpose of our study was to determine whether impairments in odor familiarity and hedonicity judgments observed in SZ patients during a previous behavioral study are associated with modifications of the activation patterns in olfactory areas. Twelve SZ patients, and 12 healthy comparison (HC) subjects, were tested using the H2(15)O-PET technique and 48 different odorants delivered during 8 scans. In addition to an odorless baseline condition, they had either to detect odor, or to judge odor familiarity or hedonicity, giving their responses by pressing a button. Regional cerebral blood flows during olfactory conditions were compared with those for baseline condition. Between-group analyses were then performed, and completed by regions of interest analyses. Both groups had equivalent ability for the detection of suprathreshold odorants, but patients found odors less familiar, and pleasant odors less pleasant than HC subjects. These behavioral results were related to functional abnormalities in temporo-limbic and orbital olfactory regions lateralized in the left hemisphere: the posterior part of the piriform cortex and orbital regions for familiarity judgments, the insular gyrus for hedonicity judgments, and the left inferior frontal gyrus and anterior piriform cortex/putamen region for the three olfactory tasks. They mainly resulted from a lack of activation during task conditions in the SZ patients. These data could explain olfactory disturbances and other clinical features of schizophrenia such as anhedonia.     

Unpleasant odors increase pain processing in a patient with neuropathic pain: psychophysical and fMRI investigation

A 49-year old man with neuropathic pain in his right elbow, wrist and digits III-V of his hand reported that certain odors increased his pain by superimposing an electric shock-like pain to his already existing pain. Psychophysical testing revealed that the best predictor of pain exacerbation was odor unpleasantness. Functional magnetic resonance imaging (fMRI) showed increased activation following an unpleasant odor in pain related areas, including the thalamus, amygdala, insular and anterior cingulate cortices, with similar trends in primary somatosensory cortex hand/arm area. The increased pain and associated neural activations in response to unpleasant odors may be related to the phenomenon of synesthesia, to a rewiring of olfactory pathways onto pain pathways mimicking synesthesia or, to activation of the sympathetic nervous system.     

Functional neuroimaging of odor imagery

We used positron emission tomography (PET) to investigate brain regions associated with odor imagery. Changes in regional cerebral blood flow (CBF) during odor imagery were compared with changes during nonspecific expectation of olfactory stimuli and with those during odor perception. Sixty-seven healthy volunteers were screened for their odor imagery (with a paradigm developed in a previous study), and 12 of them, assessed to be "good odor imagers," participated in the neuroimaging part of the study. Imagination of odors was associated with increased activation in several olfactory regions in the brain: the left primary olfactory cortical (POC) region including piriform cortex, the left secondary olfactory cortex or posterior orbitofrontal cortex (OFC), and the rostral insula bilaterally. Furthermore, blood flow in two regions within the right orbitofrontal cortex correlated significantly with the behavioral measure of odor imagery during scanning. Overall, the findings indicated that neural networks engaged during odor perception and imagery overlap partially.     

fMRI of emotional responses to odors: influence of hedonic valence and judgment, handedness, and gender

Previous positron emission tomography studies of right-handed individuals show that the left orbitofrontal cortex is dominant during emotional processing of odors. We collected functional magnetic resonance imaging data from 28 subjects to study this network as a function of odor hedonic valence (pleasant vs. unpleasant), active hedonic judgments versus passive sensation of hedonically charged odors, handedness, and gender. Two functional runs were performed, with pleasant and unpleasant odors presented in different epochs. In the first run, subjects passively smelled odorants, whereas in the second run they rated degree of odor pleasantness or unpleasantness by using a "finger-span" technique that simulated a visual rating scale. Electrodermal and plethysmography responses were simultaneously recorded to control for covert, physiological manifestations of the emotional response. The piriform-amygdala area and ventral insula were activated more for unpleasant than pleasant odors. More extreme ratings were also associated with higher electrodermal amplitude, suggesting that activation stemmed more from emotional or hedonic intensity than valence, and that unpleasant odors induced more arousal than pleasant odors. Unpleasant odors activated the left ventral insula in right-handers and the right ventral insula in left-handers, suggesting lateralized processing of emotional odors as a function of handedness. Active decisions about odor pleasantness induced specific left orbitofrontal cortex activation, implicating the role of this area in the conscious assessment of the emotional quality of odors. Finally, left orbitofrontal cortex was more active in women than men, potentially in relation to women's well-documented advantage in odor identification.     

愉快及非愉快气体激活相应脑区的功能磁共振成像实验研究

目的 采用功能磁共振成像（fMRI）观察和研究愉快及非愉快气体激活相应脑区的情况并对嗅觉中枢及其通路进行功能定位。方法12名右利手、无嗅觉障碍健康志愿者参加实验。采用乙酸戊酯为愉快刺激气体，吡啶为非愉快气体，组块设计，1．5T MRI行EPI序列扫描，用Matlab5．3及SPM99、Talairach等软件数据后处理。结果愉快及非愉快气体刺激海马回钩，丘脑内侧背核、眶额回皮质均出现明显激活，两种气味均表现为右侧大脑半球优势激活，即右侧额叶上、中、下回、右侧眶额回、右侧海马回钩以及右侧丘脑背内侧核均较左侧半球相应脑区激活明显；与情绪相关脑区亦发现激活，即额内侧回、海马旁回、扣带回、颢上回以及右侧额叶上、中、下回。愉快气体激活大脑前区为主，非愉快气体激活大脑后区明显。结论BOLD-fMRI是研究人类嗅觉功能的有效方法。本研究进一步验证了海马回钩、丘脑内侧背核和眶额回为嗅觉中枢及其重要通路，并且右侧大脑半球为嗅觉“优势半球”；气味嗅觉还引起与情绪相关脑区的激活，并且愉快情绪主要与大脑前部区域有关，不愉快情绪主要与大脑后部区域关系密切。     

Illusion of pain: pre-existing knowledge determines brain activation of 'imagined allodynia'.

Allodynia means that innocuous tactile stimulation is felt as pain. Accordingly, cerebral activations during allodynia or touch should markedly differ. The aim of this study was to investigate whether the imagination of allodynia affects brain processing of touch in healthy subjects. Seventeen healthy subjects divided into 2 subgroups were investigated: The first group (n = 7) was familiar with allodynia, based on previous pain studies, whereas the second group (n = 10) had never knowingly experienced allodynia. Using functional magnetic resonance imaging, 2 experimental conditions were investigated. In one condition the subjects were simply touched at their left hand, whereas during the other condition they were asked to imagine pain (allodynia) during tactile stimulation of the right hand and to estimate the imagined pain on a numeric rating scale. Data processing and analysis were performed with the use of SPM5. The group analysis of all subjects revealed that tactile stimulation activated contralateral somatosensory cortices (S1 [primary] and S2 [secondary]), but the imagination of allodynia led to an additional activation of anterior cingulate cortex and bilateral activation of S2, insular cortex, and prefrontal cortices. Subgroup analysis using rating-weighted predictors revealed activation of the contralateral thalamus, anterior cingulate cortex, and amygdala and a bilateral activation of S1, S2, and insular cortex and prefrontal cortices in allodynia-experienced subjects. In contrast, allodynia-inexperienced subjects only activated contralateral S1 and bilateral S2. Just the imagination that touch is painful is able to partly activate the central pain system, but only when the subject has previous experience of this. According to our results, the medial pain system is involved in the encoding of imagined allodynia. PERSPECTIVE: This article reports that pain experience is able to alter central processing of sensory stimuli. Pain knowledge appears to be able to shift "normal" tactile processing to a different quality, resulting in modified brain activity. Therefore, our study may contribute to the current understanding of human pain and will promote future research on this field.     

非优势大脑半球缺血性脑卒中患者存在的急性期脑功能连接改变:基于rs-fMRI技术

目的运用静息态脑功能成像探究非优势大脑半球缺血性脑卒中患者在急性期的脑功能连接的变化。方法以15例健康受试者作为正常对照组,15例非优势大脑半球（右半球）中动脉急性梗塞（发病 < 72 h）的患者作为卒中组,采用西门子3.0 T超导MRI采集两组患者相关数据,以功能连接为结局指标,并基于Matlab 2012a平台使用DPABI工具包对两组数据进行预处理和统计学分析。结果最终10例患者纳入试验,与健康受试者对比,差异有统计学意义（P < 0.005）的感兴趣区（ROI）有11个。以右背外侧额上回为ROI,与左后扣带回（T=6.5173）等脑区功能连接增强;以右眶部额上回为ROI,与左BA18（T=6.0674）等脑区功能连接增强;以左中央沟盖为ROI,与左距状裂周围皮层（T=5.7831）等脑区功能连接增强;以右眶内额上回为ROI,与左梭状回（T=5.7361）等脑区功能连接增强;以左岛叶为ROI,与左梭状回（T=4.5436）等脑区功能连接增强;以右岛叶为ROI,与右小脑后叶（T=4.9352）等脑区功能连接增强;以左楔叶为ROI,与左岛叶（T=5.6924）等脑区功能连接增强;与右梭状回为ROI,与左眶回（T=8.4505）等脑区功能连接增强;以左楔前叶为ROI,与左豆状壳核（T=5.1894）等脑区功能连接增强;以左中央旁小叶为ROI,与左豆状壳核（T=7.9109）等脑区功能连接增强;以左颞横回为ROI,与左舌回（T=5.9146）等脑区功能连接增强。结论非优势大脑半球缺血性脑卒中患者在急性期存在与视觉、听觉、高级认知及运动相关的脑区之间功能连接增强的脑功能变化。      

PET study on central processing of pain in trigeminal neuropathy

Recent functional brain imaging studies with positron emission tomography (PET), in painful peripheral mononeuropathy and nitroglycerin-provoked cluster headache attacks, suggest a preference of the right hemisphere, especially the anterior cingulate cortex (ACC) and the medial prefrontal cortex (MPFC), in attributing emotional valence and attention to the pain suffering. We have investigated the central processing of painful trigeminal neuropathy (PTN) in patients treated with electric extradural precentral gyrus stimulation (PCGS). Increased regional cerebral blood flow (rCBF) was detected in the right caudal ACC [Brodmann area (BA) 24] and anterior limbic thalamus, while a decreased activity was observed in the right MPFC (BA 9/32) during the habitual-pain state, in comparison with the pain-alleviated state regardless of the inflicted side of PTN. The involvement of BA 9/32 and the anterior limbic thalamus spatially extended to the left hemisphere, but the local maxima and a significant negative correlation between the rCBF changes in the two structures were found only in the right hemisphere. The activation of the caudal BA24 further supports the theory that ACC is crucial for the suffering in chronic pain. Our study not only verifies the preferential role of the right hemisphere in the appreciation of pain suffering, but further supports that sustained chronic pain, being devoid of the motivational component of an escape response, targets the right hemisphere, particularly the BA24 of the ACC.     

Limbic responses to reward cues correlate with antisocial trait density in heavy drinkers

Antisocial traits are common among alcoholics- particularly in certain subtypes. Although people with antisocial tendencies show atypical brain activation in some emotion and reward paradigms, how the brain reward systems of heavy drinkers (HD) are influenced by antisocial traits remains unclear. We used subjects' preferred alcohol drink odors (AO), appetitive (ApCO) and non-appetitive (NApO) control odors in functional magnetic resonance imaging (fMRI) to determine if reward system responses varied as a function of antisocial trait density (ASD). In this retrospective analysis, we examined 30 HD who had participated in imaging twice: once while exposed to clamped intravenous alcohol infusion targeted to 50mg%, and once during placebo saline infusion. Under placebo, there were positive correlations between ASD and blood oxygenation level dependent (BOLD) activation in the [AO>ApCO] contrast in the left dorsal putamen, while negative correlations were present in medial orbitofrontal cortex (OFC) and the bilateral amygdala. A similar pattern was observed in the correlation with the [AO>NApO] contrast. This inverse relationship between ASD and activation in OFC and amygdala was specific to AO. However, negative correlations between ASD and the [ApCO>NApO] contrast were also present in the insula, putamen, and medial frontal cortex. These data suggest that frontal and limbic reward circuits of those with significant ASD are less responsive to reward cues in general, and particularly to alcohol cues in medial OFC and amygdala. These findings are broadly consistent with the reward deficiency syndrome hypothesis, although positive correlation in the striatum suggests regional variability.     

Chronic stress is linked to 5-HT(1A) receptor changes and functional disintegration of the limbic networks

There are increasing reports about stress related cognitive and psychic declines in subjects who have no psychiatric premorbidity, depression, or major life trauma. Yet, little is known about the underlying neurobiology. Based on the typical symptomatology, fMRI data suggesting that stress activates the limbic circuits, and animal data showing a major involvement of the 5-HT(1A) receptor in stress regulation, we hypothesized that enduring daily stress causes widespread limbic dysfunctions, and specific changes of the 5-HT(1A) receptor. To test these hypotheses combined PET studies were carried out in 16 chronically stressed, and 16 non-stressed subjects. Limbic function was tested by measuring cerebral blood flow during rest, and when using an odor activation paradigm. 5-HT(1A) receptor binding potential (BP) was assessed with [(11)C]WAY100635. All subjects went through a battery of neuropsychological tests. Stressed subjects showed a functional disconnection between the amygdala and ACC/medial prefrontal cortex (mPFC), and an impaired odor activation of the ACC. They also displayed a reduced 5-HT(1A) receptor BP in the anterior cingulate (ACC), the insular-cortex, and the hippocampus. Their performance in attention-, odor discrimination-, and semantic memory tasks was impaired, and correlated with the BP-values in the respective region. The degree of reported stress was inversely correlated with activation of ACC, and the 5-HT(1A) receptor BP in the amygdala and hippocampus. Enduring every day psychosocial stress seems to be associated with a limbic reduction of 5-HT(1A) receptor binding and functional disintegration of ACC/mPFC. These changes support the notion of an impaired top-down regulation of stress stimuli, and identify potential targets for early treatment.     

Temporomandibular Disorder Modifies Cortical Response to Tactile Stimulation

Individuals with temporomandibular disorder (TMD) suffer from persistent facial pain and exhibit abnormal sensitivity to tactile stimulation. To better understand the pathophysiological mechanisms underlying TMD, we investigated cortical correlates of this abnormal sensitivity to touch. Using functional magnetic resonance imaging (fMRI), we recorded cortical responses evoked by low-frequency vibration of the index finger in subjects with TMD and in healthy controls (HC). Distinct subregions of contralateral primary somatosensory cortex (SI), secondary somatosensory cortex (SII), and insular cortex responded maximally for each group. Although the stimulus was inaudible, primary auditory cortex was activated in TMDs. TMDs also showed greater activation bilaterally in anterior cingulate cortex and contralaterally in the amygdala. Differences between TMDs and HCs in responses evoked by innocuous vibrotactile stimulation within SI, SII, and the insula paralleled previously reported differences in responses evoked by noxious and innocuous stimulation, respectively, in healthy individuals. This unexpected result may reflect a disruption of the normal balance between central resources dedicated to processing innocuous and noxious input, manifesting itself as increased readiness of the pain matrix for activation by even innocuous input. Activation of the amygdala in our TMD group could reflect the establishment of aversive associations with tactile stimulation due to the persistence of pain.     

中央区脑膜瘤患者的功能性近红外光学成像分析及文献回顾

目的评价中央区脑膜瘤患者和对照组手指运动相关的脑激活部位之区别,探讨脑功能重组的机制。方法对1例脑膜瘤患者和2例对照进行近红外脑功能成像检查。试验采用模块设计、单手对指任务,经数据处理、统计和脑功能区定位,比较患者和对照激活区域的差别。结果对照组进行单手运动时对侧大脑半球运动区激活,脑膜瘤患者右手运动时左侧初级感觉运动皮层激活,而左手运动时右侧半球（患侧）在肿瘤后外侧初级感觉运动皮层的通道出现较弱激活,而左侧半球（健侧）初级感觉运动皮层、补充运动区、运动前区出现较强激活。结论功能性近红外脑功能成像检查可检测中央区脑肿瘤患者手部运动相关的脑功能重组。     

The functional neuroanatomy of simple calculation and number repetition: A parametric PET activation study

We examined cerebral activation patterns with positron emission tomography (PET) in 12 right-handed normal volunteers while they were completing simple calculation tasks or merely repeating numbers. Using a parametric experimental design, during calculation we found activation in the medial frontal/cingulate gyri, left dorsolateral prefrontal cortex, left anterior insular cortex and right anterior insular cortex/putamen, left lateral parietal cortex, and the medial thalamus. Number repetition engaged bilateral inferior sensorimotor cortex, bilateral temporal areas, and left inferior frontal cortex. These results suggest a functional anatomical network for simple calculation, which includes aspects of attention, auditory, and motor processing and the phonological store and articulatory loop components of working memory; they add some support for a special role of the parietal cortex in calculation tasks.     

A PET activation study of brush-evoked allodynia in patients with nerve injury pain

Acute experimental brush-evoked allodynia induces a cortical activation pattern that differs from that typically seen during experimental nociceptive pain. In this study, we used positron emission tomography to measure changes in regional cerebral blood flow (rCBF) in patients with clinical allodynia. Nine patients with peripheral nerve injury were scanned during rest, brush-evoked allodynia, and brushing of normal contralateral skin. PET data were analyzed for the whole group and for single subjects. Allodynic stimulation activated the contralateral orbitofrontal cortex (BA 11) in every patient. Whereas normal brushing activated most strongly the contralateral insular cortex, allodynic brushing produced an ipsilateral activation in this area. Another important difference between normal and allodynic brushing was the absence of a contralateral primary somatosensory cortex (SI) activation during allodynic brushing. No thalamic activation was observed during allodynic or control brushing. Although no anterior cingulate cortex (ACC) activation could be demonstrated in the group analysis, single subject analysis revealed that four patients activated this region during brush-evoked allodynia. A direct post hoc comparison of brush -and allodynia-induced rCBF changes showed that allodynia was associated with significantly stronger activations in orbitofrontal cortex and ipsilateral insula whereas non-painful brushing more strongly activated SI and BA 5/7. These findings indicate that activity in the cortical network involved in the sensory-discriminative processing of nociceptive pain is downregulated in neuropathic pain. Instead, there is an upregulation of activity in the orbitofrontal and insular cortices, which is probably due to the stronger emotional load of neuropathic pain and higher computational demands of processing a mixed sensation of brush and pain.     

失眠患者杏仁核功能连接的静息态功能磁共振成像

目的分析静息状态下失眠患者杏仁核与其他脑功能连接的改变。方法失眠患者39例为失眠组,体检健康者23例为对照组,2组均进行临床匹兹堡睡眠质量指数量表(Pittsburgh Sleep Quality Index, PSQI)、汉密尔顿抑郁量表(Hamilton Depression Scale, HAMD)、汉密尔顿焦虑量表(Hamilton Anxiety Scale, HAMA)、世界卫生组织-加利福尼亚听觉词语学习测验(World Health Organization University of California Los Angeles Auditory Verbal Learning Test, WHO-UCLA AVLT)评估睡眠、认知、情绪情况,2组均行磁共振常规扫描和静息态功能MRI扫描(resting-state functional MRI, rs-fMRI),以双侧杏仁核为种子点,比较2组脑功能连接的差异;采用Pearson相关分析失眠组长时记忆评分与左侧杏仁核-左侧海马旁回、左侧杏仁核-右侧海马旁回的功能连接强度的相关性。结果失眠组PSQI[(13.46±2.74)分]、HAMA[(10.10±3.97)分]、HAMD[(9.56±3.48)分]评分及认知障碍评分[(1.23±0.67)分]明显高于对照组[(2.52±1.75)、(1.57±1.90)、(0.78±1.24)、(0.08±0.07)分](P<0.05),WHO-UCLA学习记忆量表中长时记忆[(10.67±2.35)分]和再认记忆[(12.36±2.40)分]评分低于对照组[(11.96±1.85)、(13.39±1.31)分](P<0.05);与对照组比较,失眠组左侧杏仁核与后扣带回、双侧海马旁回、双侧海马、颞叶、舌回和枕叶的功能连接增强(P<0.05),右侧杏仁核与边缘叶、右侧海马旁回、舌回、枕叶、右侧距状皮层、后扣带回、前额叶功能连接增强(P<0.05);失眠组长时记忆评分与左侧杏仁核-左侧海马旁回、左侧杏仁核-右侧海马旁回的功能连接强度呈正相关(r=0.556,P<0.001;r=0.150,P=0.032)。结论失眠患者双侧杏仁核与多个脑区的功能连接出现异常,可能是失眠患者出现情绪调节障碍、认知障碍等的机制之一。     

Sex differences in functional brain activation during noxious visceral stimulation in rats

Studies in healthy human subjects and patients with irritable bowel syndrome suggest sex differences in cerebral nociceptive processing. Here we examine sex differences in functional brain activation in the rat during colorectal distention (CRD), a preclinical model of acute visceral pain. [¹⁴C]-iodoantipyrine was injected intravenously in awake, non-restrained female rats during 60- or 0-mmHg CRD while electromyographic abdominal activity (EMG) and pain behavior were recorded. Regional cerebral blood flow-related tissue radioactivity was analyzed by statistical parametric mapping from autoradiographic images of three-dimensionally reconstructed brains. Sex differences were addressed by comparing the current data with our previously published data collected from male rats. While sex differences in EMG and pain scores were modest, significant differences were noted in functional brain activation. Females showed widespread changes in limbic (amygdala, hypothalamus) and paralimbic structures (ventral striatum, nucleus accumbens, raphe), while males demonstrated broad cortical changes. Sex differences were apparent in the homeostatic afferent network (parabrachial nucleus, thalamus, insular and dorsal anterior cingulate cortices), in an emotional–arousal network (amygdala, locus coeruleus complex), and in cortical areas modulating these networks (prefrontal cortex). Greater activation of the ventromedial prefrontal cortex and broader limbic/paralimbic changes in females suggest greater engagement of affective mechanisms during visceral pain. Greater cortical activation in males is consistent with the concept of greater cortical inhibitory effects on limbic structures in males, which may relate to differences in attentional and cognitive attribution to visceral stimuli. These findings show remarkable similarities to reported sex differences in brain responses to visceral stimuli in humans.     

The neural basis of implicit moral attitude--an IAT study using event-related fMRI

Recent models of morality have suggested the importance of affect-based automatic moral attitudes in moral reasoning. However, previous investigations of moral reasoning have frequently relied upon explicit measures that are susceptible to voluntary control. To investigate participant's automatic moral attitudes, we used a morality Implicit Association Test (IAT). Participants rated the legality of visually depicted legal and illegal behaviors of two different intensity levels (e.g., high intensity illegal = interpersonal violence; low intensity illegal = vandalism) both when the target concept (e.g., illegal) was behaviorally paired with an associated attribute (e.g., bad; congruent condition) or an unassociated attribute (e.g., good; incongruent condition). Behaviorally, an IAT effect was shown; RTs were faster in the congruent rather than incongruent conditions. At the neural level, implicit moral attitude, as indexed by increased BOLD response as a function of stimulus intensity, was associated with increased activation in the right amygdala and the ventromedial orbitofrontal cortex. In addition, performance on incongruent trials relative to congruent trials was associated with increased activity in the right ventrolateral prefrontal cortex (BA 47), left subgenual cingulate gyrus (BA 25), bilateral premotor cortex (BA 6) and the left caudate. The functional contributions of these regions in moral reasoning are discussed.     

基于比率低频振幅fMRI评价青少年网络游戏成瘾者静息态下脑功能活动

目的：采用比率低频振幅（fALFF）评价青少年网络游戏成瘾（IGA）者静息态下脑功能区激活特点.方法：对17例符合IGA诊断标准的青少年（IGA组）及19例在年龄、性别、受教育年限、利手等方面相匹配的青少年健康志愿者（正常对照组）行静息态fMRI扫描,两组间fALFF的差异采用两样本t检验.结果：与正常对照组相比,IGA组静息态下双侧额上回及额中回、右侧额内侧回、右侧扣带回前部及左侧扣带回后部、右侧海马旁回、右侧颞下回、右侧楔前叶脑区fALFF增高,差异有统计学意义（P＜0.05,未校正）.右侧颞上回及颞中回、双侧舌回、双侧枕叶、右侧胼胝体压部及双侧小脑脑区fALFF降低,差异有统计学意义（P＜0.05,未校正）.结论：IGA者静息态下脑功能存在异常,fALFF有助于对IGA者静息状态脑功能变化的理解.     

Enhanced interictal responsiveness of the migraineous visual cortex to incongruent bar stimulation: a functional MRI visual activation study

Since visual aura is usually described as expanding zigzag lines, neurones involved with the perception of line orientation may initiate this phenomenon. A visual incongruent line stimulation protocol was developed to obtain functional magnetic resonance images (fMRI) interictally in 5 female migraine patients with typical fortification spectra and in 5 normal matched controls. Activation in the visual cortex was present contralateral to the side of stimulation in 4 of 5 patients, notably in the extrastriate visual cortex. In 4 of 5 controls activation was observed in the medial and anterior orbitofrontal cortex. In one of them additional activation at the right nucleus accumbens/ventral striatum and right ventral pallidum was present. In the remaining control subject activation was present in the left primary visual cortex. The enhanced interictal reactivity of the visual cortex in migraineurs supports the hypothesis of abnormal cortical excitability as an important pathophysiological mechanism in migraine aura, though the role of specific regions of the visual cortex remains to be explored.