18F-FDG PET显像与EEG在颞叶癫痫致痫灶定位价值上的对比研究

目的：通过对62例难治性癫痫患者进行前瞻性研究,对18F-FDG PET显像与EEG在颞叶癫痫致痫灶定位上的价值进行对比研究。方法：对62例临床确诊颞叶癫痫并接受手术治疗的患者进行前瞻性研究。所有患者均进行发作间期PET-CT脑显像检查和长程/视频EEG检查,细致分析图像,并将所得检查结果与术后病理进行比较,利用统计学方法对二者的诊断准确率进行对比分析。结果：18F-FDG PET显像准确定位42例癫痫患者病灶位置,头皮EEG准确定位致痫灶30例,准确率分别为67.7%及48.4%,二者比较有显著统计学差异（P<0.05）。18F-FDG PET显像结果表现较多样,影像分析应细致、审慎。结论：发作间期PET-CT脑显像检查定位颞叶癫痫致痫灶优于长程/视频EEG检查,但因其价格较昂贵,临床可首选EEG定位癫痫,EEG定位困难时选择PET显像可明显提高致痫灶定位准确性。     

Dynamic imaging of ictal oscillations using non-invasive high-resolution EEG

Scalp electroencephalography (EEG) has been established as a major component of the pre-surgical evaluation for epilepsy surgery. However, its ability to localize seizure onset zones (SOZ) has been significantly restricted by its low spatial resolution and indirect correlation with underlying brain activities. Here we report a novel non-invasive dynamic seizure imaging (DSI) approach based upon high-density EEG recordings. This novel approach was particularly designed to image the dynamic changes of ictal rhythmic discharges that evolve through time, space and frequency. This method was evaluated in a group of 8 epilepsy patients and results were rigorously validated using intracranial EEG (iEEG) (n=3) and surgical outcome (n=7). The DSI localized the ictal activity in concordance with surgically resected zones and ictal iEEG recordings in the cohort of patients. The present promising results support the ability to precisely and accurately image dynamic seizure activity from non-invasive measurements. The successful establishment of such a non-invasive seizure imaging modality for surgical evaluation will have a significant impact in the management of medically intractable epilepsy.     

Integrating EEG and fMRI in epilepsy

Integrating electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) studies enables to non-invasively investigate human brain function and to find the direct correlation of these two important measures of brain activity. Presurgical evaluation of patients with epilepsy is one of the areas where EEG and fMRI integration has considerable clinical relevance for localizing the brain regions generating interictal epileptiform activity. The conventional analysis of EEG-fMRI data is based on the visual identification of the interictal epileptiform discharges (IEDs) on scalp EEG. The convolution of these EEG events, represented as stick functions, with a model of the fMRI response, i.e. the hemodynamic response function, provides the regressor for general linear model (GLM) analysis of fMRI data. However, the conventional analysis is not automatic and suffers of some subjectivity in IEDs classification. Here, we present an easy-to-use and automatic approach for combined EEG-fMRI analysis able to improve IEDs identification based on Independent Component Analysis and wavelet analysis. EEG signal due to IED is reconstructed and its wavelet power is used as a regressor in GLM. The method was validated on simulated data and then applied on real data set consisting of 2 normal subjects and 5 patients with partial epilepsy. In all continuous EEG-fMRI recording sessions a good quality EEG was obtained allowing the detection of spontaneous IEDs and the analysis of the related BOLD activation. The main clinical finding in EEG-fMRI studies of patients with partial epilepsy is that focal interictal slow-wave activity was invariably associated with increased focal BOLD responses in a spatially related brain area. Our study extends current knowledge on epileptic foci localization and confirms previous reports suggesting that BOLD activation associated with slow activity might have a role in localizing the epileptogenic region even in the absence of clear interictal spikes.     

BOLD correlates of continuously fluctuating epileptic activity isolated by independent component analysis

Combined EEG/fMRI recordings offer a promising opportunity to detect brain areas with altered BOLD signal during interictal epileptic discharges (IEDs). These areas are likely to represent the irritative zone, which is itself a reflection of the epileptogenic zone. This paper reports on the imaging findings using independent component analysis (ICA) to continuously quantify epileptiform activity in simultaneously acquired EEG and fMRI. Using ICA derived factors coding for the epileptic activity takes into account that epileptic activity is continuously fluctuating with each spike differing in amplitude, duration and maybe topography, including subthreshold epileptic activity besides clear IEDs and may thus increase the sensitivity and statistical power of combined EEG/fMRI in epilepsy. Twenty patients with different types of focal and generalized epilepsy syndromes were investigated. ICA separated epileptiform activity from normal physiological brain activity and artifacts. In 16/20 patients, BOLD correlates of epileptic activity matched the EEG sources, the clinical semiology, and, if present, the structural lesions. In clinically equivocal cases, the BOLD correlates aided to attribute proper diagnosis of the underlying epilepsy syndrome. Furthermore, in one patient with temporal lobe epilepsy, BOLD correlates of rhythmic delta activity could be employed to delineate the affected hippocampus. Compared to BOLD correlates of manually identified IEDs, the sensitivity was improved from 50% (10/20) to 80%. The ICA EEG/fMRI approach is a safe, non-invasive and easily applicable technique, which can be used to identify regions with altered hemodynamic effects related to IEDs as well as intermittent rhythmic discharges in different types of epilepsy.     

婴幼儿癫痫的临床和脑电图特点分析

目的研究各型婴幼儿癫痫发作特征、脑电图、病因、神经影像学的改变,探讨早期诊断方法及预后。方法对我院2003年6月-2008年1月门诊和住院诊治的125例3岁以内起病的婴幼儿癫痫患儿进行临床观察及脑电图监测,并进行CT或MRI等神经影像学及血生化、尿遗传代谢病筛查等辅助检查,随访治疗效果和远期预后。结果本组1岁以内发病占54．4％。全面性发作占37．6％,局灶性发作占53．6％,不能明确分类的发作占8．8％。症状性癫痫占58．4％,其中围生期异常是第一位病因,占症状性癫痫的50．68％;特发性癫痫占41．6％。脑电图背景活动正常占53．6％,异常占46．4％,发作问期EEG正常占24．8％,异常占75．2％。影像学检查异常占38．4％。结论婴幼儿以症状性癫痫多见,局灶性发作所占的比例高,发作形式多样,应与非癫痫性发作鉴别,视频脑电图检查对诊断及鉴别有重要意义。     

脑结构和功能MR成像研究儿童失神癫痫进展

儿童失神癫痫(CAE)是常见儿童癫痫综合征，以频发的一过性意识障碍伴脑电图(EEG)双侧同步性广泛棘慢波放电(GSWD)为特征。无创神经成像技术有助于探索CAE患儿大脑结构变化，从而阐述其发生发展机制。本文就脑结构和功能MR成像研究CAE进展进行综述。     

Epilepsy

Seizures are common and are treated in all branches of medicine. Approximately 10% of the population will have one or more seizures during their lifetime. Seizures are symptoms that occur in acute illness, ie, provoked seizures, or in epilepsy, ie, unprovoked seizures. Epilepsy is any disorder in which spontaneous recurrence of unprovoked seizures is the main symptom. It is a common chronic neurologic disorder and affects 1% to 3% of the population. Classification of seizure type is important because it enables identification of the region of the brain where the seizure originated and guides initial diagnostic testing. Classification of epilepsy syndrome, rather than only type of seizure, is more important. Epilepsy syndromes are defined by many factors, including type of seizures, age at onset of seizures, family history of seizures, and findings at physical examination, electroencephalography (EEG), and neurologic imaging studies. Identifying the epilepsy syndrome provides insight into natural history, prognosis, diagnostic testing, and therapy of the disorder and facilitates communication between health care professionals. Understanding seizure type provides useful information even when the epilepsy syndrome cannot be classified. Many sudden events are easily confused with seizures, in particular, pseudoseizures, syncope, migraine, cerebrovascular disease, movement disorders, and sleep disorders. In most cases a detailed history and physical examination concentrated on the details of the event, and results of routine EEG and magnetic resonance imaging can aid in determination of which events are seizures. Video EEG monitoring is occasionally necessary to capture events to enable definitive determination of whether they are seizures and to further characterize them. Provoked seizures are treated with relief of the provoking factor. Antiepileptic drugs (AEDs) are not indicated. However, AEDs may be required to treat unprovoked seizures of new onset in patients at high risk for seizure recurrence or when a second seizure can have devastating psychosocial effects. High risk for recurrence is present when there is a history of brain insult, an EEG demonstrates epileptiform abnormalities, and magnetic resonance images demonstrate a structural lesion. AED therapy is the standard treatment for epilepsy, ie, two or more seizures. Selection of the appropriate AED depends on type of seizure and epilepsy present, and individual drug characteristics, including pharmacokinetics, side effects, dosing interval, and cost. All available AEDs except ethosuximide are effective as adjunctive therapy, and most are effective as initial monotherapy for partial seizures. Generalized seizures preferentially respond to valproate, lamotrigine, and topiramate, among other drugs. If trials of more than two AEDs do not control seizures, additional AEDs are unlikely to be effective, and the patient should be referred to an epilepsy center, where other treatment options, in particular, epilepsy surgery, can be offered. Epilepsy surgery renders 60% to 70% of patients with temporal lobe epilepsy free of disabling seizures.     

联合应用SPECT、EEG、MRI定位癫痫致痫灶53例分析

目的探讨单光子发射计算机断层(SPECT)脑血流灌注显像联合动态脑电图和(或)视频脑电图、磁共振成像(MRI)检查在定位癫痫致痫灶中的意义.方法对53例癫痫患者于发作间期进行99mTc-ECD局部脑血流灌注显像,并与同期动态脑电图和(或)视频脑电图、MRI检查、术中皮层脑电图检查结果进行对比分析.结果 SPECT脑血流灌注显像诊断癫痫的阳性率为88.68%,与脑电图(EEG)检查的阳性率(86.79%)一致,但二者均明显高于MRI检查阳性率(33.96%),且STECT联合EEG检查,阳性率可提升至98.11%(52/53),明显高于SPECT或EEG单独检查的阳性率;在定位致痫灶过程中,SPECT脑血流显像与EEG在致痫灶的定位上具有良好的吻合性,其符合率(包括定位一致及基本一致者)为60.37%,明显高于SPECT与MRI检查的符合率(35.85%)及EEG与MRI的符合率(32.07%);经术中皮层脑电图检查证实SPECT定位致痫灶的准确率达83.33%,若与EEG、MRI联合分析则其定位准确率提升至95.8%(23/24).结论 SPECT脑血流灌注显像不仅能灵敏地检出癫痫灶,且能较准确地定位诊断癫痫灶,与EEG和MRI的联合应用可大大提高其诊断的灵敏度和定位的准确性.     

The value of neuroimaging in diagnosis of epilepsy

Neuroimaging examines the relationship between abnormalities of brain function in epilepsy patients (seizures, impaired cognitive function, psychiatric co-morbidity etc.) and focal or more widespread brain pathology. Since the mid-1980s, the introduction of magnetic resonance imaging (MRI) into clinical neurology has had an impact on the diagnosis, treatment, and research of epilepsy only comparable with the advent of the electroencephalography (EEG) fifty years ago. MRI plays the important role of identifying single or multiple structural lesions responsible for the epileptic seizures. Thus, visual assessment of MRI plays an important role in the differentiation between symptomatic, cryptogenic, and idiopathic epilepsies. This diagnostic step leads to therapeutic decisions (medical treatment vs. surgery) and prognostic evaluations. If a structural lesion identified with MRI correlates with seizure-type, EEG and other clinical data, the likelihood of rendering the patient seizure free with epilepsy surgery is increased. Clinical research into epilepsy uses quantitative MRI (volumetry, T2-relaxometry, magnetic resonance spectroscopy [MRS], voxel-based morphometry) to reduce those cases initially labeled as cryptogenic. Quantitative MRI questions the belief that there is epilepsy without structural brain abnormality at all. Functional MRI (fMRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT) demonstrate changes associated with epileptic seizures and pathology, and changes associated with EEG abnormalities and their cessation. Functional neuroimaging is also used for the identification of functional brain tissue before surgery. Physiologically or pathologically active neuronal tissue is believed to be identified by glucose or oxygen consumption (PET), cerebral blood flow (PET, SPECT, perfusion MRI), and cerebral blood oxygenation (blood oxygenation level dependent [BOLD] fMRI). PET also offers the opportunity to visualize the in-vivo distribution of neuronal receptors which are implicated in the generation, the spread, and the cessation of seizures.     

Three-dimensional brain current source reconstruction from intra-cranial ECoG recordings

We have investigated 3-dimensional brain current density reconstruction (CDR) from intracranial electrocorticogram (ECoG) recordings by means of finite element method (FEM). The brain electrical sources are modeled by a current density distribution and estimated from the ECoG signals with the aid of a weighted minimum norm estimation algorithm. A series of computer simulations were conducted to evaluate the performance of ECoG-CDR by comparing with the scalp EEG based CDR results. The present computer simulation results indicate that the ECoG-CDR provides enhanced performance in localizing single dipole sources which are located in regions underneath the implanted subdural ECoG grids, and in distinguishing and imaging multiple separate dipole sources, in comparison to the CDR results as obtained from the scalp EEG under the same conditions. We have also demonstrated the applicability of the present ECoG-CDR method to estimate 3-dimensional current density distribution from the subdural ECoG recordings in a human epilepsy patient. Eleven interictal epileptiform spikes (seven from the frontal region and four from parietal region) in an epilepsy patient undergoing surgical evaluation were analyzed. The present promising results indicate the feasibility and applicability of the developed ECoG-CDR method of estimating brain sources from intracranial electrical recordings, with detailed forward modeling using FEM.     

Safety and seizure control in patients with mesial temporal lobe epilepsy treated with regional superselective intra‐arterial injection of autologous bone marrow mononuclear cells

Temporal lobe epilepsy (TLE) is a highly prevalent syndrome among people with epilepsy, and is usually refractory to drug treatment. Structural and physiological changes, such as hippocampal sclerosis, are often present in TLE patients. The objective of this study is to evaluate the feasibility and safety of intra‐arterial infusion of autologous bone marrow mononuclear cells (BMMC) in adults with medically refractory mesial TLE (MTLE) and unilateral hippocampal sclerosis (HS). We enrolled 20 patients who had been diagnosed with MTLE‐HS and were refractory to medical treatment. All patients underwent a neurological evaluation, magnetic resonance imaging with hippocampal volumetry, video‐electroencephalography (EEG) with ictal recording, and a neuropsychological test battery focusing on verbal and nonverbal memory domains. After bone marrow aspiration and subsequent cell preparation, the BMMC were infused by selective posterior cerebral artery catheterization. Patients were followed for 6 months. Safety of the procedure, seizure frequency, neuropsychological evaluation, EEG variables, routine brain magnetic resonance imaging and hippocampal volumetry were considered measurements of outcome. Any serious intercurrent clinical event or adverse effects related to the procedure were reported. No additional lesions and no significant hippocampal volumetric changes were observed. EEG recordings showed a decrease in theta activity and spike density. At 6 months, eight patients (40%) were seizure free. A significant increase in the memory scores over time was observed. The BMMC autologous transplant for the treatment of temporal lobe epilepsy is feasible and safe. The seizure control achieved in this novel study supports the therapeutic potential of stem cell transplants in MTLE‐HS patients. Copyright © 2016 John Wiley & Sons, Ltd.     

Localization of abnormal discharges causing insular epilepsy by magnetoencephalography

The insula, one of the five cerebral lobes of the brain, is located deep within the brain and lies mainly beneath the temporal lobe. Insular epilepsy can be easily confused and misdiagnosed as temporal lobe epilepsy (TLE) because of the similar clinical symptoms and scalp electroencephalography (EEG) findings due to the insula location and neuronal connections with the temporal lobe. Magnetoencephalography (MEG) has higher sensitivity and spatial resolution than scalp EEG, and thus can often identify epileptic discharges not revealed by scalp EEG. Simultaneous scalp EEG and MEG were performed to detect and localize epileptic discharges in two patients known to have insular epilepsy associated with cavernous angioma in the insula. Epileptic discharges were detected as abnormal spikes in the EEG and MEG findings. In Patient 1, the sources of all MEG spikes detected simultaneously by EEG and MEG (E/M-spikes) were localized in the anterior temporal lobe, similar to TLE. In contrast, the sources of all MEG spikes detected only by MEG (M-spikes) were adjacent to the insular lesion. In Patient 2, the sources of all MEG spikes detected simultaneously by EEG and MEG (E/M-spikes) were localized in the anterior temporal lobe. These findings indicate that MEG allows us to detect insular activity that is undetectable by scalp EEG. In conclusion, simultaneous EEG and MEG are helpful for detecting spikes and obtaining additional information about the epileptic origin and propagation in patients with insular epilepsy.     

Decoding word and category-specific spatiotemporal representations from MEG and EEG

The organization and localization of lexico-semantic information in the brain has been debated for many years. Specifically, lesion and imaging studies have attempted to map the brain areas representing living versus nonliving objects, however, results remain variable. This may be due, in part, to the fact that the univariate statistical mapping analyses used to detect these brain areas are typically insensitive to subtle, but widespread, effects. Decoding techniques, on the other hand, allow for a powerful multivariate analysis of multichannel neural data. In this study, we utilize machine-learning algorithms to first demonstrate that semantic category, as well as individual words, can be decoded from EEG and MEG recordings of subjects performing a language task. Mean accuracies of 76% (chance=50%) and 83% (chance=20%) were obtained for the decoding of living vs. nonliving category or individual words respectively. Furthermore, we utilize this decoding analysis to demonstrate that the representations of words and semantic category are highly distributed both spatially and temporally. In particular, bilateral anterior temporal, bilateral inferior frontal, and left inferior temporal-occipital sensors are most important for discrimination. Successful intersubject and intermodality decoding shows that semantic representations between stimulus modalities and individuals are reasonably consistent. These results suggest that both word and category-specific information are present in extracranially recorded neural activity and that these representations may be more distributed, both spatially and temporally, than previous studies suggest.     

EEG source analysis of epileptiform activity using a 1 mm anisotropic hexahedra finite element head model

The major goal of the evaluation in presurgical epilepsy diagnosis for medically intractable patients is the precise reconstruction of the epileptogenic foci, preferably with non-invasive methods. This paper evaluates whether surface electroencephalography (EEG) source analysis based on a 1 mm anisotropic finite element (FE) head model can provide additional guidance for presurgical epilepsy diagnosis and whether it is practically feasible in daily routine. A 1 mm hexahedra FE volume conductor model of the patient's head with special focus on accurately modeling the compartments skull, cerebrospinal fluid (CSF) and the anisotropic conducting brain tissues was constructed using non-linearly co-registered T1-, T2- and diffusion-tensor-magnetic resonance imaging data. The electrodes of intra-cranial EEG (iEEG) measurements were extracted from a co-registered computed tomography image. Goal function scan (GFS), minimum norm least squares (MNLS), standardized low resolution electromagnetic tomography (sLORETA) and spatio-temporal current dipole modeling inverse methods were then applied to the peak of the averaged ictal discharges EEG data. MNLS and sLORETA pointed to a single center of activity. Moving and rotating single dipole fits resulted in an explained variance of more than 97%. The non-invasive EEG source analysis methods localized at the border of the lesion and at the border of the iEEG electrodes which mainly received ictal discharges. Source orientation was towards the epileptogenic tissue. For the reconstructed superficial source, brain conductivity anisotropy and the lesion conductivity had only a minor influence, whereas a correct modeling of the highly conducting CSF compartment and the anisotropic skull was found to be important. The proposed FE forward modeling approach strongly simplifies meshing and reduces run-time (37 ms for one forward computation in the model with 3.1 million unknowns), corroborating the practical feasibility of the approach.     

A cortical potential imaging study from simultaneous extra- and intracranial electrical recordings by means of the finite element method

In the present study, we have validated the cortical potential imaging (CPI) technique for estimating cortical potentials from scalp EEG using simultaneously recorded electrocorticogram (ECoG) in the presence of strong local inhomogeneity, i.e., Silastic ECoG grid(s). The finite element method (FEM) was used to model the realistic postoperative head volume conductor, which includes the scalp, skull, cerebrospinal fluid (CSF) and brain, as well as the Silastic ECoG grid(s) implanted during the surgical evaluation in epilepsy patients, from the co-registered magnetic resonance (MR) and computer tomography (CT) images. A series of computer simulations were conducted to evaluate the present FEM-based CPI technique and to assess the effect of the Silastic ECoG grid on the scalp EEG forward solutions. The present simulation results show that the Silastic ECoG grid has substantial influence on the scalp potential forward solution due to the distortion of current pathways in the presence of the extremely low conductive materials. On the other hand, its influence on the estimated cortical potential distribution is much less than that on the scalp potential distribution. With appropriate numerical modeling and inverse estimation techniques, we have demonstrated the feasibility of estimating the cortical potentials from the scalp EEG with the implanted Silastic ECoG gird(s), in both computer simulations and in human experimentation. In an epilepsy patient undergoing surgical evaluation, the cortical potentials were reconstructed from the simultaneously recorded scalp EEG, in which main features of spatial patterns during interictal spike were preserved and over 0.75 correlation coefficient value was obtained between the recorded and estimated cortical potentials. The FEM-based CPI technique provides a means of connecting the simultaneous recorded ECoG and the scalp EEG and promises to become an effective tool to evaluate and validate CPI techniques using clinic data.     

The imaging of epilepsy

Based on the experience of a university neurological epilepsy center, the neurological classification and the gradation of neurological evaluation of patients with epilepsy are described. Into this the nature and the significance of the imaging of the brain are interwoven. The object, illustrated by several illustrative patients, is to stress the importance of the MRI and to note that based on the MRI findings and the clinical findings, the battery of sophisticated electroencephalographic evaluation is determined. Epilepsy is an area where imaging and all aspects of the clinical neurological evaluation integrate very well and in which correlation is most important.     

老年人迟发性癫痫发作53例临床分析

目的　探讨老年人迟发性癫痫的病因、临床特点、脑电图及影像学特征。方法　回顾分析5 3例老年人迟发性癫痫的临床、脑电图及脑CT资料。结果　癫痫发作的可能病因为脑血管病31例,脑外伤7例,脑萎缩7例,脑肿瘤3例,蛛网膜囊肿1例,硬膜下积液1例,颅内感染1例,不明原因2例。临床发作类型为全身性强直 阵挛发作31例,部分性发作发展至全身性发作4例,部分性发作18例。脑电图共查2 1例,其中异常18例(痫样放电2例,其余主要表现为弥漫性或局限性慢波)。脑CT检查5 1例,异常4 9例。结论　老年人迟发性癫痫多数有明确病因。全身性发作是其主要临床发作类型。影像学检查多能发现病灶,以脑叶病变为多。     

Epilepsy surgery, resection volume and MSI localization in lesional frontal lobe epilepsy

To verify whether interictal noninvasive information detected by magnetoencephalography (MEG) recordings can contribute to localize focal epileptic activity relevant for seizure generation in lesional frontal lobe epilepsy, magnetic source imaging (MSI) localizations of epileptic discharges were compared to the extent of neurosurgical resection and postoperative outcome. Preoperative MEG spike localizations were displayed in postoperative magnetic resonance imaging (MRI) scans to check whether dipole sites were located within the resection cavity. Moreover, MEG localizations were compared with results of prolonged video-EEG monitoring and, in three cases, with invasive EEG recordings. Our results in five cases with lesional frontal lobe epilepsy showed that good surgical outcome could be achieved in those patients where the majority of MEG spike localizations were located within the resected brain volume.     

Assessment of dementia

The evaluation for dementia has to answer three questions: first, if there is indeed a dementia or if there is perhaps a delirium or a mild cognitive impairment. Dementia targeted interviewing of the patients and their relatives have to be followed by neuropsychological evaluations. Dementia screening tests are the mini mental state examination in combination with a clock drawing test. For an early diagnosis, a more comprehensive neuropsychological assessment by specialists is needed. For confirmation of a diagnosis of dementia, a nosological differential diagnosis including a physical, especially neurological and psychological examination, laboratory tests and perhaps an EEG or brain imaging is necessary. At least, a careful evaluation of caregiver burdens is absolutely necessary for medico-social interventions.     

Spatiotemporal Brain Imaging of Visual-Evoked Activity Using Interleaved EEG and fMRI Recordings

Combined analysis of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has the potential to provide higher spatiotemporal resolution than either method alone. In some situations, in which the activity of interest cannot be reliably reproduced (e.g., epilepsy, learning, sleep states), accurate combined analysis requires simultaneous acquisition of EEG and fMRI. Simultaneous measurements ensure that the EEG and fMRI recordings reflect the exact same brain activity state. We took advantage of the spatial filtering properties of the bipolar montage to allow recording of very short (125–250 ms) visual-evoked potentials (VEPs) during fMRI. These EEG and fMRI measurements are of sufficient quality to allow source localization of the cortical generators. In addition, our source localization approach provides a combined EEG/fMRI analysis that does not require any manual selection of fMRI activations or placement of source dipoles. The source of the VEP was found to be located in the occipital cortex. Separate analysis of EEG and fMRI data demonstrated good spatial overlap of the observed activated sites. As expected, the combined EEG/fMRI analysis provided better spatiotemporal resolution than either approach alone. The resulting spatiotemporal movie allows for the millisecond-to-millisecond display of changes in cortical activity caused by visual stimulation. These data reveal two peaks in activity corresponding to the N75 and the P100 components. This type of simultaneous acquisition and analysis allows for the accurate characterization of the location and timing of neurophysiological activity in the human brain.