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fMRI-constrained source analysis of visual P300 in Landolt ring task
YueZhi Li,Tao Xu,LiQun Wang,Yong Hu
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0060-8
Abstract: An fMRI-constrained source analysis was applied to investigate visual P300 in the Landolt ring task. To study the localization and relative activation timing of P300 generators, we implemented simultaneous EEG/fMRI to identify BOLD signal changes and record 64-channel EEG in 10 subjects during a Landolt ring task inside a 1.5-T fMRI scanner using an MR-compatible EEG recording system. MRI artifact subtraction software was applied to obtain continuous EEG data. Then, the simultaneous collecting of EEG and fMRI was validated in preserving relevant ERPs. The fMRI-constrained source analysis resulted in an 8-dipole solution. The bilateral middle frontal and the right inferior parietal dipole waveforms showed a short latency peak corresponding to the early P300 activity, while the four parietal and the anterior cingulate dipole waveforms showed a long latency peak corresponding to the late P300 activity. The longest latency peak of the anterior cingulate dipole agrees with its role in initiation of motor response after successful target recognition. Target detection in the Landolt ring task produces the strongest and most extensive parietal activation (especially superior parietal activation), which might be due to its particular visual attention switching.
P300电位中p3b成分的脑电同步功能磁共振研究  [PDF]
李岳峙,王力群,王明时
科学通报 , 2005,
Abstract: 采用脑电同步功能磁共振成像技术研究P300事件相关电位中与P3b成分相关的BOLD信号及其脑源定位.11个受试者在1.5T功能磁共振扫描仪中进行一项Landot圆环作业,测试过程中每隔4s采用回波平面成像法对全脑进行一次扫描,扫描时间为2s,扫描间歇2s,同时采用与功能磁共振扫描仪兼容的64导脑电采集系统记录受试者脑电信号,并使用磁共振伪迹清除软件对信号去伪迹得到连续EEG波形.另外,设计了P300匹配滤波器检查每次靶刺激出现后的脑电信号段,筛查出能够诱发产生P300波的靶刺激,分析这些靶刺激发生前后的磁共振扫描图像序列,建立磁共振统计参数图并进行校正,最后完成多参数比较.其中通过Randomeffectsgroup方法发现双侧下顶叶和右上顶叶显著激活(P<0.001,未校正).研究表明以上区域是记忆比较P300任务中P3b成分的脑激活源,它们参与这一任务的目标判断过程.
fMRI-constrained source analysis of visual P300 in Landolt ring task
LI YueZhi,XU Tao,WANG LiQun,HU Yong,

科学通报(英文版) , 2008,
Abstract: An fMRI-constrained source analysis was applied to investigate visual P300 in the Landolt ring task. To study the localization and relative activation timing of P300 generators, we implemented simultaneous EEG/fMRI to identify BOLD signal changes and record 64-channel EEG in 10 subjects during a Landolt ring task inside a 1.5-T fMRI scanner using an MR-compatible EEG recording system. MRI artifact sub-traction software was applied to obtain continuous EEG data. Then, the simultaneous collecting of EEG and fMRI was validated in preserving relevant ERPs. The fMRI-constrained source analysis resulted in an 8-dipole solution. The bilateral middle frontal and the right inferior parietal dipole waveforms showed a short latency peak corresponding to the early P300 activity, while the four parietal and the anterior cingulate dipole waveforms showed a long latency peak corresponding to the late P300 activity. The longest latency peak of the anterior cingulate dipole agrees with its role in initiation of motor re-sponse after successful target recognition. Target detection in the Landolt ring task produces the strongest and most extensive parietal activation (especially superior parietal activation), which might be due to its particular visual attention switching.
The BOLD response and the gamma oscillations respond differently than evoked potentials: an interleaved EEG-fMRI study
Jack R Foucher, Hélène Otzenberger, Daniel Gounot
BMC Neuroscience , 2003, DOI: 10.1186/1471-2202-4-22
Abstract: Both Targets and Novels triggered a P300, of larger amplitude in the Novel condition. On the opposite, the fMRI BOLD response was stronger in the Target condition. EEG event-related oscillations in the gamma band (32–38 Hz) reacted in a way similar to the BOLD response.The reasons for such opposite differential reactivity between oscillations / fMRI on the one hand, and evoked potentials on the other, are discussed in the paper. Those results provide further arguments for a closer relationship between fast oscillations and the BOLD signal, than between evoked potentials and the BOLD signal.There are two core methods to explore human brain function: direct measurement of the electrical activity, as with the electro-encephalogram (EEG), or measurement of the vascular response that is indirectly related to the neuronal activity, as in functional MRI (fMRI) [1]. Because both approaches have complementary advantages, attempts have been made to fuse the high temporal resolution of EEG, with the high spatial resolution of fMRI. Although animal data have made it possible to elucidate some of the relationships between neuronal activity and the Blood Oxygen Level-Dependant contrast (BOLD) [2-5], there is much left to be worked out about the actual relationship between EEG and fMRI. This paper aims at presenting some data showing, through differential reactivity, that not all kinds of EEG responses might be related to the BOLD contrast.It has been reported that variations in BOLD contrast in response to the presentation of two kinds of rare events, i.e. oddballs, presented a differential reactivity opposite to that observed using Evoked Potentials (EPs). Oddballs are known to evoke a P300, a positive EP around 300–400 ms [6]. EPs are computed by averaging the EEG signal time-locked to the presentation of a stimulus. Activity time-locked to the stimulus emerges from background EEG activity, which is not time-locked and averages to zero [7]. The P300 is mainly perceived on the m
EEG-assisted retrospective motion correction for fMRI: E-REMCOR  [PDF]
Vadim Zotev,Han Yuan,Raquel Phillips,Jerzy Bodurka
Physics , 2012, DOI: 10.1016/j.neuroimage.2012.07.031
Abstract: We propose a method for retrospective motion correction of fMRI data in simultaneous EEG-fMRI that employs the EEG array as a sensitive motion detector. EEG motion artifacts are used to generate motion regressors describing rotational head movements with millisecond temporal resolution. These regressors are utilized for slice-specific motion correction of unprocessed fMRI data. Performance of the method is demonstrated by correction of fMRI data from five patients with major depressive disorder, who exhibited head movements by 1-3 mm during a resting EEG-fMRI run. The fMRI datasets, corrected using eight to ten EEG-based motion regressors, show significant improvements in temporal SNR (TSNR) of fMRI time series, particularly in the frontal brain regions and near the surface of the brain. The TSNR improvements are as high as 50% for large brain areas in single-subject analysis and as high as 25% when the results are averaged across the subjects. Simultaneous application of the EEG-based motion correction and physiological noise correction by means of RETROICOR leads to average TSNR enhancements as high as 35% for large brain regions. These TSNR improvements are largely preserved after the subsequent fMRI volume registration and regression of fMRI motion parameters. The proposed EEG-assisted method of retrospective fMRI motion correction (referred to as E-REMCOR) can be used to improve quality of fMRI data with severe motion artifacts and to reduce spurious correlations between the EEG and fMRI data caused by head movements. It does not require any specialized equipment beyond the standard EEG-fMRI instrumentation and can be applied retrospectively to any existing EEG-fMRI data set.
Contradictory Reasoning Network: An EEG and fMRI Study  [PDF]
Camillo Porcaro, Maria Teresa Medaglia, Ngoc Jade Thai, Stefano Seri, Pia Rotshtein, Franca Tecchio
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0092835
Abstract: Contradiction is a cornerstone of human rationality, essential for everyday life and communication. We investigated electroencephalographic (EEG) and functional magnetic resonance imaging (fMRI) in separate recording sessions during contradictory judgments, using a logical structure based on categorical propositions of the Aristotelian Square of Opposition (ASoO). The use of ASoO propositions, while controlling for potential linguistic or semantic confounds, enabled us to observe the spatial temporal unfolding of this contradictory reasoning. The processing started with the inversion of the logical operators corresponding to right middle frontal gyrus (rMFG-BA11) activation, followed by identification of contradictory statement associated with in the right inferior frontal gyrus (rIFG-BA47) activation. Right medial frontal gyrus (rMeFG, BA10) and anterior cingulate cortex (ACC, BA32) contributed to the later stages of process. We observed a correlation between the delayed latency of rBA11 response and the reaction time delay during inductive vs. deductive reasoning. This supports the notion that rBA11 is crucial for manipulating the logical operators. Slower processing time and stronger brain responses for inductive logic suggested that examples are easier to process than general principles and are more likely to simplify communication.
Causality within the Epileptic Network: An EEG-fMRI Study Validated by Intracranial EEG  [PDF]
Anna Elisabetta Vaudano,Laura Tassi,Andrea Ruggieri,Gaetano Cantalupo,Francesca Benuzzi,Paolo Nichelli,Louis Lemieux,Stefano Meletti
Frontiers in Neurology , 2013, DOI: 10.3389/fneur.2013.00185
Abstract: Accurate localization of the Seizure Onset Zone (SOZ) is crucial in patients with drug-resistance focal epilepsy. EEG with fMRI recording (EEG-fMRI) has been proposed as a complementary non-invasive tool, which can give useful additional information in the pre-surgical work-up. However, fMRI maps related to interictal epileptiform activities (IED) often show multiple regions of signal change, or “networks,” rather than highly focal ones. Effective connectivity approaches like Dynamic Causal Modeling (DCM) applied to fMRI data potentially offers a framework to address which brain regions drives the generation of seizures and IED within an epileptic network. Here, we present a first attempt to validate DCM on EEG-fMRI data in one patient affected by frontal lobe epilepsy. Pre-surgical EEG-fMRI demonstrated two distinct clusters of blood oxygenation level dependent (BOLD) signal increases linked to IED, one located in the left frontal pole and the other in the ipsilateral dorso-lateral frontal cortex. DCM of the IED-related BOLD signal favored a model corresponding to the left dorso-lateral frontal cortex as driver of changes in the fronto-polar region. The validity of DCM was supported by: (a) the results of two different non-invasive analysis obtained on the same dataset: EEG source imaging (ESI), and “psycho-physiological interaction” analysis; (b) the failure of a first surgical intervention limited to the fronto-polar region; (c) the results of the intracranial EEG monitoring performed after the first surgical intervention confirming a SOZ located over the dorso-lateral frontal cortex. These results add evidence that EEG-fMRI together with advanced methods of BOLD signal analysis is a promising tool that can give relevant information within the epilepsy surgery diagnostic work-up.
Recording Visual Evoked Potentials and Auditory Evoked P300 at 9.4T Static Magnetic Field  [PDF]
Jorge Arrubla, Irene Neuner, David Hahn, Frank Boers, N. Jon Shah
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062915
Abstract: Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4T were not different from those recorded at 0T. The amplitudes of ERPs were higher at 9.4T when compared to recordings at 0T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.
Multimodal Functional Network Connectivity: An EEG-fMRI Fusion in Network Space  [PDF]
Xu Lei, Dirk Ostwald, Jiehui Hu, Chuan Qiu, Camillo Porcaro, Andrew P. Bagshaw, Dezhong Yao
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024642
Abstract: EEG and fMRI recordings measure the functional activity of multiple coherent networks distributed in the cerebral cortex. Identifying network interaction from the complementary neuroelectric and hemodynamic signals may help to explain the complex relationships between different brain regions. In this paper, multimodal functional network connectivity (mFNC) is proposed for the fusion of EEG and fMRI in network space. First, functional networks (FNs) are extracted using spatial independent component analysis (ICA) in each modality separately. Then the interactions among FNs in each modality are explored by Granger causality analysis (GCA). Finally, fMRI FNs are matched to EEG FNs in the spatial domain using network-based source imaging (NESOI). Investigations of both synthetic and real data demonstrate that mFNC has the potential to reveal the underlying neural networks of each modality separately and in their combination. With mFNC, comprehensive relationships among FNs might be unveiled for the deep exploration of neural activities and metabolic responses in a specific task or neurological state.
Epileptic Discharges Affect the Default Mode Network – fMRI and Intracerebral EEG Evidence  [PDF]
Firas Fahoum, Rina Zelmann, Louise Tyvaert, Fran?ois Dubeau, Jean Gotman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068038
Abstract: Functional neuroimaging studies of epilepsy patients often show, at the time of epileptic activity, deactivation in default mode network (DMN) regions, which is hypothesized to reflect altered consciousness. We aimed to study the metabolic and electrophysiological correlates of these changes in the DMN regions. We studied six epilepsy patients that underwent scalp EEG-fMRI and later stereotaxic intracerebral EEG (SEEG) sampling regions of DMN (posterior cingulate cortex, Pre-cuneus, inferior parietal lobule, medial prefrontal cortex and dorsolateral frontal cortex) as well as non-DMN regions. SEEG recordings were subject to frequency analyses comparing sections with interictal epileptic discharges (IED) to IED-free baselines in the IED-generating region, DMN and non-DMN regions. EEG-fMRI and SEEG were obtained at rest. During IEDs, EEG-fMRI demonstrated deactivation in various DMN nodes in 5 of 6 patients, most frequently the pre-cuneus and inferior parietal lobule, and less frequently the other DMN nodes. SEEG analyses demonstrated decrease in gamma power (50–150 Hz), and increase in the power of lower frequencies (<30 Hz) at times of IEDs, in at least one DMN node in all patients. These changes were not apparent in the non-DMN regions. We demonstrate that, at the time of IEDs, DMN regions decrease their metabolic demand and undergo an EEG change consisting of decreased gamma and increased lower frequencies. These findings, specific to DMN regions, confirm in a pathological condition a direct relationship between DMN BOLD activity and EEG activity. They indicate that epileptic activity affects the DMN, and therefore may momentarily reduce the consciousness level and cognitive reserve.
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