儿童期失神癫痫静息态脑网络改变的脑电图联合功能磁共振成像研究

目的采用静息态功能磁共振(fMRI)脑网络分析技术对儿童失神发作时静息态脑网络的改变进行观察,旨在发现癫癎发作时患儿认知功能受损情况。方法根据病例选择标准,共纳入12例诊断明确的失神发作患儿,采用同步脑电图-fMRI技术采集17对弥漫性棘慢波综合发放和无发放状态下fMRI数据;以独立成分分析法分别观察丘脑、默认网络、背侧注意网络、中央执行网络和感知觉网络等7个静息态脑网络在不同状态下的表现情况。结果配对t检验及相关分析结果提示,在弥漫性棘慢波综合发放状态下丘脑表现为脑电活动同步性增强,且其强度与弥漫性棘慢波综合发放持续时间呈正相关(r=0.890,P=0.000);默认网络(r=-0.706,P=0.000)、背侧注意网络(r=-0.829,P=0.000)、中央执行网络(r=-0.905,P=0.000)等负责高级认知功能处理的静息态脑网络则表现为脑电活动同步性降低,并与弥漫性棘慢波综合发放持续时间呈负相关。而低级的感知觉网络的改变与弥漫性棘慢波综合发放无显著相关关系(P>0.05)。结论本研究首次验证丘脑可能与儿童期失神癫癎弥漫性棘慢波综合发放有关,并首次提出,除默认网络功能外,儿童失神发作还可表现为注意力及执行控制能力等高级认知功能受损,而低级感知觉功能虽可能受累但不明显。这一发现有益于对儿童失神发作时意识受损的病理生理学机制的理解。     

静息态功能磁共振成像临床应用扫描时间的优化研究

目的探讨静息态fMRI临床应用的最优化扫描时问。方法采用分数低频振荡振幅（fALFF）值观察16例亚急性期脑桥单发梗死患者（脑梗死组）静息态fMRI扫描6和12min时各脑区默认网络,并与年龄、性别相匹配的正常对照者（对照组）脑默认网络激活范围和强度进行比较。结果静息态fMRI扫描6和12min时,两组受试者各脑区默认网络均被激活,其中对照组两次扫描的脑区包括扣带回前后部、前楔叶、双侧角回和顶下小叶、前额叶,与以往对照者的脑默认网络研究结果相似;4个经典脑区的默认网络在不同测量时间点（6和12min）的激活程度,差异无统计学意义（均P〉0．05）。脑梗死组患者两个测量时间点均获得与对照组相同的默认网络经典脑区,且两个测量时间点的激活程度差异亦无统计学意义（均P〉0．05）,但12min时扫描的头动参数略大于6min时。结论脑梗死组患者静息态fMRI以扫描6min为更优化时间,对临床疾病的研究具有重要参考价值。     

基于功能磁共振成像的早发精神分裂症默认网络研究

目的：探讨早发精神分裂患者在静息状态下脑默认网络功能连接特点。方法：采用功能磁共振成像（fMRI）技术,对26例早发精神分裂症患者和28例正常对照进行静息状态下全脑的磁共振脑功能扫描。采用功能连接分析方法,提取静息状态下默认网络,在患者组和对照组中分别计算默认网络各脑区两两间的功能连接。结果：早发精神分裂症组在默认网络存在5条异常连接。其中3条连接表现为连接增强：腹侧前额叶内侧皮质-右侧颞下回（P=0.0078）,腹侧前额叶内侧皮质-左侧外侧顶叶（P=0.0091）、腹侧前额叶内侧皮质-背侧前额叶内侧皮质（P=0.0163）。2条连接表现为连接减弱：右侧外侧顶叶-小脑扁桃体（P=0.0223）,左侧额上回-右侧下半月小叶（P=0.0294）。结论：早发精神分裂症患者存在默认网络功能的异常。这些异常改变可能与精神分裂症的病理机制相关。     

γ—氨基丁酸B受体参与猴实验性失神癫痫发作

本研究观察了γ－氨基丁酸能Ｂ受体激动剂氯苯氨丁酸和新型γ－氨基丁酸能Ｂ受体阻断剂ＣＧＰ４６３８１对猕猴由γ－羟基丁酸诱发的实验性失神癫痫发作状态的影响。静脉注射γ－羟基丁酸（２００和４００ｍｇ／ｋｇ）诱发剂量依赖性类失神癫痫发作样行为和脑电变化，其特点是双侧同步的“棘一慢波”，放电频率为１．２８～２．０８Ｈｚ（１．６０±０．１０Ｈｚ）。氯苯氨丁酸使”棘一慢波”放电时间增加，而ＣＧＰ４６３８１则使“棘一慢波”放电时间明显缩短，两者均为剂量依赖性的。静脉单独注射氯苯氨了酸也可引出类失神癫痫发作样行为和脑电变化，“棘一慢波”频率为１．２５～２．３３Ｈｚ（１．７６±０．１２Ｈｚ）。结果提示脑内Ｂ型γ－氨基丁酸能递质活动的增强很可能是失神性癫痫发作的主要原因。同时，γ－氨基丁酸能Ｂ受体阻断剂有希望成为新型抗癫痫药物。     

海洛因成瘾者默认网络功能改变的静息态功能磁共振成像研究北大核心CSCD

目的 探讨海洛因成瘾者默认网络的功能影像学改变。方法 14例海洛因成瘾者（海洛因成瘾组）和14名对照者（对照组）进行静息态fMRI扫描,采用独立成分分析方法分别提取海洛因成瘾组和对照组的默认网络进行组内及组间分析,以了解成瘾者默认网络功能连接改变的脑区。结果 与对照组比较,海洛因成瘾组默认网络的额上回内侧（t＝-2.61）、前扣带回（t＝-3.32）及楔叶（t左＝-3.49,t右＝-3.40）的功能连接减弱,后扣带回（t＝4.55）、楔前叶（t左＝4.31,t右＝3.54）以及角回（t左＝2.57,t右＝6.39）的功能连接增强,均P〈0.05。结论 静息态下海洛因成瘾者的默认网络存在功能连接异常。     

抑郁症静息态大脑双侧杏仁核的功能连接

目的：探讨静息态下抑郁症患者大脑半球双侧杏仁核的功能连接特点，了解杏仁核及其功能相关脑区在抑郁症病理机制中的作用。方法：11例首次发作的重性抑郁症患者与11例性别、年龄、受教育程度均与患者相匹配的正常人完成静息态功能性磁共振成像（fMRI）扫描。利用Pearson相关分析方法分析受试者大脑双侧的杏仁核功能连接强度，并利用双样本t检验做组间对比，设P〈0．05为差异具有显著性。结果：静息态下，两组双侧杏仁核均具有明显的功能连接（P〈0．05），而抑郁症组较对照组的功能连接明显减低（P=0．025）。结论：静息态下抑郁症组双侧杏仁核功能连接存在异常，这可能与抑郁症患者杏仁核异常及杏仁核与其他情感调节相关脑区的协调异常有关。     

部分性发作癫痫患者静息状态功能磁共振默认模式网络的功能连接改变

目的 应用静息状态功能磁共振成像(fMRI)探讨部分性发作癫痫患者静息状态下的脑功能改变.方法 对60例部分性发作癫痫患者(患者组)和60名性别、年龄和教育程度匹配的健康对照者(对照组),使用3.0T磁共振采集两组的静息状态下fMRI数据,采用功能连接方法分析计算脑区的默认模式网络的功能连接,利用SPM5软件分析比较患者组和对照组脑功能的差异.结果 患者组的默认模式网络的功能连接主要包括左侧楔前叶/后扣带回和角回、扣带回;对照组的功能连接主要包括左侧楔前叶/后扣带回和右侧角回,双侧内侧额叶和颞叶;患者组的左侧顶下小叶[坐标值(x,y,z):-57,-39,48;t=4.90,P＜0.01]、左侧缘上回[坐标值(x,y,z):-63,- 48,33;t=4.25,P＜0.01]、左侧海马旁回[坐标值(x,y,z):-30,-6,-21;t =4.05,P＜0.01]、左侧颞上回[坐标值(x,y,z):-48,-39,6;t=3.72,P＜0.01],左侧钩回[坐标值(x,y,z):-24,6,- 36;=4.56,P＜0.01]及右侧钩回[坐标值(x,y,z):33,-15,- 36;t=4.00,P＜0.01]的默认模式网络功能连接较对照组降低;未发现功能连接升高的脑区.结论 部分性发作癫痫患者静息状态下脑区的功能连接改变,可能是部分性发作癫痫潜在的病理生理机制.静息状态fMRI能发现常规MRI正常的癫痫患者的广泛脑功能异常,是一种无创的研究癫痫患者脑功能的有效方法.     

伴中央-中颞棘波的儿童良性癫癎与弥漫性棘慢波综合及失神发作的关系

目的 探讨弥漫性棘慢波综合(GSWD)及失神发作(AS)在儿童良性癫痫伴中央，中颞棘波发放(BECCT)患者中的发生情况，分析BECCT与AS间的可能的相互联系。方法 回顾性分析5年来诊断为BECCT的524例患者的临床及录像脑电图(VEEG)资料。我们对GSWD的入选标准为：在正常背景活动中，突然发生和中止、频率2.5～3．5Hz、双侧对称或大致对称的棘慢波综合(棘波数≤2)。结果在524例BECCT患者中，GSWD及AS的发生率分别为5．3％和2．0％。绝大多数合并有AS的BECCT患者对单药治疗效果较好。结论 BECCT和AS可发生在同一例患者中，提示这两种常见的癫痫综合征之间可能存在某些类似的发病机制。     

失神癫痫最佳治疗方案的探讨

本文总结近几年用丙戊酸钠治疗典型失神癫痫或合并全身强直-阵挛癫痫,并提出我们认为最佳的治疗方案。 方法与资料 一、病例选择 按国际癫痫发作与癫痫分类的诊断标准,临床上有典型的失神发作,清醒或睡眠脑电图上有3Hz弥漫性双侧对称棘-慢波发放者才归入本组。典型失神癫痫组男18例,女28例,就诊时年龄4.4～     

脑白质疏松症伴轻度认知损害患者静息态功能磁共振成像研究

目的采用f MRI研究脑白质疏松症伴或不伴轻度认知损害患者静息态脑网络功能连接,探讨静息态fMRI对脑白质疏松症的早期诊断价值。方法共49例脑白质疏松症患者根据临床痴呆评价量表评分分为脑白质疏松症伴轻度认知损害组(LA-MCI组,34例)和脑白质疏松症不伴轻度认知损害组(LA-NMCI组,15例),采用简易智能状态检查量表、蒙特利尔认知评价量表、汉密尔顿抑郁量表17项和汉密尔顿焦虑量表14项评价认知功能、抑郁和焦虑症状,静息态f MRI研究脑网络功能连接。结果LA-MCI组患者年龄大于正常对照组(P=0.003),MMSE(P=0.001,0.000)和Mo CA(P=0.001,0.000)评分高于LA-NMCI组和正常对照组。与正常对照组相比,LA-MCI组患者突显网络内部核团功能连接减弱,突显网络对脑默认网络核团的功能连接呈增强趋势、对中央执行网络的功能连接呈减弱趋势;LA-NMCI组患者突显网络内部核团功能连接减弱,突显网络对脑默认网络核团的功能连接呈增强趋势、对中央执行网络核团的功能连接呈减弱趋势。结论脑白质疏松症伴或不伴轻度认知损害患者静息态激活脑区与正常人群存在差异,可以在一定程度上解释脑白质疏松症伴认知功能障碍的病理生理学机制。     

Epileptic discharges specifically affect intrinsic connectivity networks during absence seizures

Intrinsic connectivity network (ICN) technique provides a feasible way for evaluating cognitive impairments in epilepsy. This EEG–fMRI study aims to comprehensively assess the alterations of ICNs affected by generalized spike-and-wave discharge (GSWD) during absence seizure (AS). Twelve fMRI sessions with GSWD, and individually paired non-GSWD sessions were acquired from 16 patients with AS. Ten ICNs corresponding to seizure origination and cognitive processes were extracted using independent component analysis. Intra- and inter-network connectivity alterations of the ICNs were observed through comparisons between GSWD and non-GSWD sessions. Sequential correlation analysis between GSWD and the ICN time courses addressed the immediate effects of GSWD on ICNs during AS. GSWD-related increase of intra-network connectivity was found only in the thalamus, and extensive decreases were found in the ICNs corresponding to higher-order cognitive processes including the default-mode network, dorsal attention network, central executive network and salience network. The perceptive networks and motor network were less affected by GSWD. Sequential correlation analysis further demonstrated different responses of the ICNs to GSWD. In addition to GSWD-related functional excitation in the thalamus and functional suspension in the default-mode network, this study revealed extensive inhibitions in the other ICNs corresponding to higher-order cognitive processes, and spared perceptive and motor processes in AS. GSWD elevated synchronization of brain network activity and sequentially affected the ICNs.     

Functional connectivity in patients with idiopathic generalized epilepsy

Purpose: Idiopathic generalized epilepsy (IGE) is characterized by electroencephalography (EEG) recordings with generalized spike wave discharges (GSWDs) arising from normal background activity. Although GSWDs are the result of highly synchronized activity in the thalamocortical network, EEG without GSWDs is believed to represent normal brain activity. The aim of this study was to investigate whether thalamocortical interactions are altered even during GSWD‐free EEG periods in patients with IGE. Methods: A GSWD‐related group analysis was performed in 12 IGE patients to define seeds in areas involved during GSWDs. EEG–functional magnetic resonance imaging (fMRI) datasets from 22 IGE patients without GSWDs during the investigation and 30 age‐matched healthy controls were then selected to investigate functional connectivity in GSWD‐related areas. Blood oxygen level dependent (BOLD) signal changes were extracted from seeds defined by the GSWD‐related group analysis. The averaged time course within each seed was used to detect brain regions with BOLD signal correlated with the seed. Group differences between patients and controls were estimated. Key Findings: The GSWD‐related group analysis showed BOLD activation in the thalamus, the frontomesial cortex, and the cerebellum and BOLD deactivation in default mode areas. For the connectivity analysis, eight seeds were placed bilaterally in the thalamus, mesial frontal cortex, precuneus, and cerebellum. The functional connectivity analysis of these seeds did not show clearly altered functional connectivity for patients versus controls. Significance: The results underscore the paroxysmal nature of GSWDs: Although GSWDs are characterized by highly synchronized activity in the thalamocortical network, the functional connectivity in areas involved during GSWDs does not demonstrate abnormality in GSWD‐free periods.     

Resting-state functional connectivity in major depression: abnormally increased contributions from subgenual cingulate cortex and thalamus.

BACKGROUND: Positron emission tomography (PET) studies of major depression have revealed resting-state abnormalities in the prefrontal and cingulate cortices. Recently, fMRI has been adapted to examine connectivity within a specific resting-state neural network--the default-mode network--that includes medial prefrontal and anterior cingulate cortices. The goal of this study was to examine resting-state, default-mode network functional connectivity in subjects with major depression and in healthy controls. METHODS: Twenty-eight subjects with major depression and 20 healthy controls underwent 5-min fMRI scans while resting quietly. Independent component analysis was used to isolate the default-mode network in each subject. Group maps of the default-mode network were compared. A within-group analysis was performed in the depressed group to explore effects of depression refractoriness on functional connectivity. RESULTS: Resting-state subgenual cingulate and thalamic functional connectivity with the default-mode network were significantly greater in the depressed subjects. Within the depressed group, the length of the current depressive episode correlated positively with functional connectivity in the subgenual cingulate. CONCLUSIONS: This is the first study to explore default-mode functional connectivity in major depression. The findings provide cross-modality confirmation of PET studies demonstrating increased thalamic and subgenual cingulate activity in major depression. Further, the within-subject connectivity analysis employed here brings these previously isolated regions of hypermetabolism into the context of a disordered neural network. The correlation between refractoriness and subgenual cingulate functional connectivity within the network suggests that a quantitative, resting-state fMRI measure could be used to guide therapy in individual subjects.     

Thalamocortical connectivity is enhanced following functional hemispherotomy for intractable lateralized epilepsy

Although developmental outcomes may improve following functional hemispherotomy for lateralized, catastrophic childhood epilepsy, the neuronal processes mediating these improvements are unknown. We report the case of a 14-year-old child with neurocognitive impairment who underwent functional hemispherotomy with longitudinal resting-state fMRI. Compared with preoperative fMRI, we report significantly more robust thalamo-default mode network connectivity on postoperative neuroimaging. Furthermore, we show decreased connectivity to nodes within the disconnected hemisphere, providing direct evidence that functional interactions are dependent upon structural connectivity. Since the vascular supply to these nodes remains intact, although they are disconnected from the remainder of the brain, these findings also confirm that blood-oxygen level dependent oscillations are driven primarily by neuronal activity. The current study highlights the importance of thalamocortical interactions in the understanding of neural oscillations and cognitive function, and their impairment in childhood epilepsy.     

Increased cortical BOLD signal anticipates generalized spike and wave discharges in adolescents and adults with idiopathic generalized epilepsies

Purpose: Electroencephalography–functional magnetic resonance imaging (EEG‐fMRI) coregistration has recently revealed that several brain structures are involved in generalized spike and wave discharges (GSWDs) in idiopathic generalized epilepsies (IGEs). In particular, deactivations and activations have been observed within the so‐called brain default mode network (DMN) and thalamus, respectively. In the present study we analyzed the dynamic time course of blood oxygen level–dependent (BOLD) changes preceding and following 3 Hz GSWDs in a group of adolescent and adult patients with IGE who presented with absence seizures (AS). Our aim was to evaluate cortical BOLD changes before, during, and after GSWD onset. Methods: Twenty‐one patients with IGE underwent EEG‐fMRI coregistration. EEG‐related analyses were run both at the single‐subject and at group level (random effect). The time‐course analysis was conducted for 3 s time windows before, during, and after GSWDs, and they were included until no further BOLD signal changes were observed. Key Findings: Fifteen patients (nine female, mean age 28 years) had GSWDs during EEG‐fMRI coregistration (262 total events, mean duration 4 s). Time‐course group analysis showed BOLD increments starting approximately 10 s before GSWD onset located in frontal and parietal cortical areas, and especially in the precuneus‐posterior cingulate region. At GSWD onset, BOLD increments were located in thalamus, cerebellum, and anterior cingulate gyrus, whereas BOLD decrements were observed in the DMN regions persisting until 9 s after onset. Significance: Hemodynamic changes (BOLD increments) occurred in specific cortical areas, namely the precuneus/posterior cingulate, lateral parietal, and frontal cortices, several seconds before EEG onset of GSWD. A dysfunction of these brain regions, some of which belongs to the DMN, may be crucial in generating GSWDs in patients with IGE.     

Social network theory applied to resting-state fMRI connectivity data in the identification of epilepsy networks with iterative feature selection

Epilepsy is a brain disorder usually associated with abnormal cortical and/or subcortical functional networks. Exploration of the abnormal network properties and localization of the brain regions involved in human epilepsy networks are critical for both the understanding of the epilepsy networks and planning therapeutic strategies. Currently, most localization of seizure networks come from ictal EEG observations. Functional MRI provides high spatial resolution together with more complete anatomical coverage compared with EEG and may have advantages if it can be used to identify the network(s) associated with seizure onset and propagation. Epilepsy networks are believed to be present with detectable abnormal signatures even during the interictal state. In this study, epilepsy networks were investigated using resting-state fMRI acquired with the subjects in the interictal state. We tested the hypothesis that social network theory applied to resting-state fMRI data could reveal abnormal network properties at the group level. Using network data as input to a classification algorithm allowed separation of medial temporal lobe epilepsy (MTLE) patients from normal control subjects indicating the potential value of such network analyses in epilepsy. Five local network properties obtained from 36 anatomically defined ROIs were input as features to the classifier. An iterative feature selection strategy based on the classification efficiency that can avoid 'over-fitting' is proposed to further improve the classification accuracy. An average sensitivity of 77.2% and specificity of 83.86% were achieved via 'leave one out' cross validation. This finding of significantly abnormal network properties in group level data confirmed our initial hypothesis and provides motivation for further investigation of the epilepsy process at the network level.     

Brain connectivity during resting state and subsequent working memory task predicts behavioural performance

Brain regions simultaneously activated during any cognitive process are functionally connected, forming large-scale networks. These functional networks can be examined during active conditions [i.e., task-functional magnetic resonance imaging (fMRI)] and also in passive states (resting-fMRI), where the default mode network (DMN) is the most widely investigated system. The role of the DMN remains unclear, although it is known to be responsible for the shift between resting and focused attention processing. There is also some evidence for its malleability in relation to previous experience. Here we investigated brain connectivity patterns in 16 healthy young subjects by using an n-back task with increasing levels of memory load within the fMRI context. Prior to this working memory (WM) task, participants were trained outside fMRI with a shortened test version. Immediately after, they underwent a resting-state fMRI acquisition followed by the full fMRI n-back test. We observed that the degree of intrinsic correlation within DMN and WM networks was maximal during the most demanding n-back condition (3-back). Furthermore, individuals showing a stronger negative correlation between the two networks under both conditions exhibited better behavioural performance. Interestingly, and despite the fact that we considered eight different resting-state fMRI networks previously identified in humans, only the connectivity within the posteromedial parts of the DMN (precuneus) prior to the fMRI n-back task predicted WM execution. Our results using a data-driven probabilistic approach for fMRI analysis provide the first evidence of a direct relationship between behavioural performance and the degree of negative correlation between the DMN and WM networks. They further suggest that in the context of expectancy for an imminent cognitive challenge, higher resting-state activity in the posteromedial parietal cortex may be related to increased attentional preparatory resources.     

Cognitive Effort and Schizophrenia Modulate Large-Scale Functional Brain Connectivity

Schizophrenia (SZ) is characterized by cognitive dysfunction and disorganized thought, in addition to hallucinations and delusions, and is regarded a disorder of brain connectivity. Recent efforts have been made to characterize the underlying brain network organization and interactions. However, to which degree connectivity alterations in SZ vary across different levels of cognitive effort is unknown. Utilizing independent component analysis (ICA) and methods for delineating functional connectivity measures from functional magnetic resonance imaging (fMRI) data, we investigated the effects of cognitive effort, SZ and their interactions on between-network functional connectivity during 2 levels of cognitive load in a large and well-characterized sample of SZ patients (n = 99) and healthy individuals (n = 143). Cognitive load influenced a majority of the functional connections, including but not limited to fronto-parietal and default-mode networks, reflecting both decreases and increases in between-network synchronization. Reduced connectivity in SZ was identified in 2 large-scale functional connections across load conditions, with a particular involvement of an insular network. The results document an important role of interactions between insular, default-mode, and visual networks in SZ pathophysiology. The interplay between brain networks was robustly modulated by cognitive effort, but the reduced functional connectivity in SZ, primarily related to an insular network, was independent of cognitive load, indicating a relatively general brain network-level dysfunction.Key words: psychotic disorders, cognition, brain networks, independent component analysis     

Abnormal functional global and local brain connectivity in female patients with anorexia nervosa

BackgroundPrevious resting-state functional connectivity studies in patients with anorexia nervosa used independent component analysis or seed-based connectivity analysis to probe specific brain networks. Instead, modelling the entire brain as a complex network allows determination of graph-theoretical metrics, which describe global and local properties of how brain networks are organized and how they interact.MethodsTo determine differences in network properties between female patients with acute anorexia nervosa and pairwise matched healthy controls, we used resting-state fMRI and computed well-established global and local graph metrics across a range of network densities.ResultsOur analyses included 35 patients and 35 controls. We found that the global functional network structure in patients with anorexia nervosa is characterized by increases in both characteristic path length (longer average routes between nodes) and assortativity (more nodes with a similar connectedness link together). Accordingly, we found locally decreased connectivity strength and increased path length in the posterior insula and thalamus.LimitationsThe present results may be limited to the methods applied during preprocessing and network construction.ConclusionWe demonstrated anorexia nervosa–related changes in the network configuration for, to our knowledge, the first time using resting-state fMRI and graph-theoretical measures. Our findings revealed an altered global brain network architecture accompanied by local degradations indicating wide-scale disturbance in information flow across brain networks in patients with acute anorexia nervosa. Reduced local network efficiency in the thalamus and posterior insula may reflect a mechanism that helps explain the impaired integration of visuospatial and homeostatic signals in patients with this disorder, which is thought to be linked to abnormal representations of body size and hunger.     

Representation and propagation of epileptic activity in absences and generalized photoparoxysmal responses

Although functional imaging studies described networks associated with generalized epileptic activity, propagation patterns within these networks are not clear. In this study, electroencephalogram (EEG)‐based coherent source imaging dynamic imaging of coherent sources (DICS) was applied to different types of generalized epileptiform discharges, namely absence seizures (10 patients) and photoparoxysmal responses (PPR) (eight patients) to describe the representation and propagation of these discharges in the brain. The results of electrical source imaging were compared to EEG‐functional magnetic resonance imaging (fMRI) which had been obtained from the same data sets of simultaneous EEG and fMRI recordings. Similar networks were described by DICS and fMRI: (1) absence seizures were associated with thalamic involvement in all patients. Concordant results were also found for brain areas of the default mode network and the occipital cortex. (2) Both DICS and fMRI identified the occipital, parietal, and the frontal cortex in a network associated with PPR. (3) However, only when PPR preceded a generalized tonic‐clonic seizure, the thalamus was involved in the generation of PPR as shown by both imaging techniques. Partial directed coherence suggested that during absences, the thalamus acts as a pacemaker while PPR could be explained by a cortical propagation from the occipital cortex via the parietal cortex to the frontal cortex. In conclusion, the electrical source imaging is not only able to describe similar neuronal networks as revealed by fMRI, including deep sources of neuronal activity such as the thalamus, but also demonstrates interactions interactions within these networks and sheds light on pathogenetic mechanisms of absence seizures and PPR. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.