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Andrzej Cichocki - One of the best experts on this subject based on the ideXlab platform.
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multiband entropy based feature extraction method for automatic identification of Epileptic Focus based on high frequency components in interictal ieeg
Scientific Reports, 2020Co-Authors: Most Sheuli Akter, Toshihisa Tanaka, Md Rabiul Islam, Yasushi Iimura, Hidenori Sugano, Kosuke Fukumori, Duo Wang, Andrzej CichockiAbstract:Presurgical investigations for categorizing focal patterns are crucial, leading to localization and surgical removal of the Epileptic Focus. This paper presents a machine learning approach using information theoretic features extracted from high-frequency subbands to detect the Epileptic Focus from interictal intracranial electroencephalogram (iEEG). It is known that high-frequency subbands (>80 Hz) include important biomarkers such as high-frequency oscillations (HFOs) for identifying Epileptic Focus commonly referred to as the seizure onset zone (SOZ). In this analysis, the multi-channel interictal iEEG signals were splitted into segments and each segment was decomposed into multiple high-frequency subbands. The different types of entropy were calculated for each of the subbands and the sparse linear discriminant analysis (sLDA) was applied to select the prominent entropy features. Due to the imbalance of SOZ and non-SOZ channels in iEEG data, the use of machine learning techniques is always tricky. To deal with the imbalanced learning problem, an adaptive synthetic oversampling approach (ADASYN) with radial basis function kernel-based SVM was used to detect the focal segments. Finally, the Epileptic Focus was identified based on detection of focal segments on SOZ and non-SOZ channels. Eight patients were examined to observe the efficiency of the automatic detector. The experimental results and statistical tests indicate that the proposed automatic detector can identify the Epileptic Focus accurately and efficiently.
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single class svm and directed transfer function approach to the localization of the region containing Epileptic Focus
Neurocomputing, 2009Co-Authors: Bartosz Swiderski, Andrzej Cichocki, S Osowski, Andrzej RyszAbstract:The paper presents the study concerning the application of a single-class support vector machine (SVM) and directed transfer function method for the localization of the region of the brain containing the Epileptic Focus on the basis of EEG registration. The results of the performed numerical experiments for the localization of the seizure Focus in the brain will be demonstrated on the examples of EEG for few patients.
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single class svm classifier for localization of Epileptic Focus on the basis of eeg
International Joint Conference on Neural Network, 2008Co-Authors: Bartosz Swiderski, Andrzej Cichocki, S Osowski, Andrzej RyszAbstract:The paper presents the application of a single-class Support Vector Machine (SVM) for localization of the Focus region at the Epileptic seizure on the basis of EEG registration. The diagnostic features used in recognition are derived from the directed transfer function description, determined for different ranges of EEG signals. The results of the performed numerical experiments for the localization of the seizure Focus in the brain have been confirmed by the real surgery of the brain for few patients.
Nobuhiro Mikuni - One of the best experts on this subject based on the ideXlab platform.
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high frequency activity overriding cortico cortical evoked potentials reflects altered excitability in the human Epileptic Focus
Clinical Neurophysiology, 2017Co-Authors: Katsuya Kobayashi, Riki Matsumoto, Masao Matsuhashi, Kiyohide Usami, Akihiro Shimotake, Takeharu Kunieda, Takayuki Kikuchi, Kazumichi Yoshida, Nobuhiro MikuniAbstract:Abstract Objective We aimed to clarify that high frequency activity (HFA) of cortico-cortical evoked potentials (CCEPs), elicited by single pulse electrical stimulation (SPES), reflects cortical excitability. Methods We recruited 16 patients with refractory partial epilepsy who had chronic subdural electrode implantation for presurgical evaluation. A repetitive SPES was given to (1) the seizure onset zone (SOZ) and (2) the control cortices (non-seizure onset zone: nSOZ). CCEPs were recorded from the neighboring cortices within SOZ and nSOZ. We applied short-time Fourier transform to obtain the induced responses for the timing of early ( 200 Hz) bands. Results Twenty-one clear CCEPs were recorded for both the SOZ and nSOZ. The HFA power of early CCEPs in SOZ significantly increased compared to that in nSOZ in both frequency bands, particularly in mesial temporal lobe epilepsy (MTLE). Conclusion Similar to the features of spontaneous pathological HFOs, the power of stimulus-induced HFAs in SOZ were greater than that outside SOZ, particularly in MTLE. Significance HFA overriding CCEPs can be a surrogate marker of cortical excitability in Epileptic Focus.
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o1 e 9 hfo correlates of cortico cortical evoked potentials reveal altered excitability in the human Epileptic Focus
Clinical Neurophysiology, 2013Co-Authors: Katsuya Kobayashi, Riki Matsumoto, Hidenao Fukuyama, Nobuhiro Mikuni, Masao Matsuhashi, Kiyohide Usami, Akihiro Shimotake, Takeharu Kunieda, Susumu Miyamoto, Ryosuke TakahashiAbstract:By using cortico-cortical evoked potentials [CCEP: early negative (N1) and late negative (N2) components], we aimed to clarify high frequency oscillation (HFO) correlates of CCEPs and its relation to human epileptogenesis. We recruited 12 patients with intractable partial epilepsy who underwent invasive presurgical evaluation with chronic implantation of subdural electrodes. Repetitive single-pulse electrical stimulation (1 Hz) was applied to (1) the seizure onset zone (SOZ) and (2) the control cortex (nSOZ), and CCEPs were recorded from the surrounding cortices within SOZ and nSOZ, respectively. We applied short-time Fourier transform to obtain induced responses at the timing of N1 (HFON1) and N2 (HFON2) and analyzed the logarithmic power change of HFON1 and HFON2 in reference to the baseline activity for ripple (120–200 Hz) and fast ripple (>200 Hz) bands. Seventeen clear CCEP responses were recorded for both SOZ and nSOZ across patients. In both SOZ and nSOZ stimulation, HFON1 generally showed power increase and HFON2 power decrease across the 2 frequency bands. HFON1 power at SOZ increased more significantly than that at nSOZ in FR band. The present study suggests HFO correlates of CCEPs could be a surrogate marker of abnormally enhanced cortical excitability in human Epileptic Focus.
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Usefulness of MEG magnetometer for spike detection in patients with mesial temporal Epileptic Focus
NeuroImage, 2008Co-Authors: Rei Enatsu, Junya Taki, Tahamina Begum, Takashi Nagamine, Riki Matsumoto, Akio Ikeda, Nobuhiro Mikuni, Jun Matsubayashi, Keiko Usui, Hidenao FukuyamaAbstract:Abstract The present study investigated the sensitivity of magnetoencephalography (MEG) for spikes depending on sensor type in patients with mesial temporal Epileptic Focus. We recorded MEG in 6 patients with mesial temporal Epileptic Focus using two sensor types (magnetometer and gradiometer) simultaneously. The number of spikes detected and the corresponding equivalent current dipole (ECD) parameters (distance from the coordinated head center (radius), and dipole moment) were evaluated with respect to sensor type. Among 426 MEG ‘consensus spikes’ determined by 3 reviewers, 378 spikes satisfied the predetermined criteria for source localization. Comparing ECD parameters, spikes detected by magnetometer alone displayed a smaller radius and larger dipole moment than those detected by gradiometer alone. Spikes estimated in the mesial temporal area were more frequently detected by magnetometer alone (38.5%) than by gradiometer alone (11.5%), whereas spikes in the lateral temporal area were detected less by magnetometer alone (3.7%) than by gradiometer alone (53.9%). The present results suggest that a magnetometer is advantageous for spike detection in patients with mesial temporal Epileptic Focus. This also implies the higher sensitivity of magnetometer for deep sources.
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low frequency electric cortical stimulation has an inhibitory effect on Epileptic Focus in mesial temporal lobe epilepsy
Epilepsia, 2002Co-Authors: Junichi Yamamoto, Riki Matsumoto, Akio Ikeda, Nobuhiro Mikuni, Takeshi Satow, Kazuhide Takeshita, Motohiro Takayama, Masao Matsuhashi, Shinji Ohara, Jun TakahashiAbstract:Summary: Purpose: This study was conducted to investigate the effect of low-frequency electric cortical stimulation on Epileptic Focus in humans. Methods: We stimulated the Epileptic Focus in a patient with medically intractable mesial temporal lobe epilepsy (MTLE) by means of subdural electrodes and evaluated the change in the number of interictal epileptiform discharges. We used biphasic electric current of 0.3-ms duration presented at 0.9-Hz frequency for 250 s, comparing stimulus intensity of 7.5, 2, and 0.5 mA. Results: Interictal epileptiform discharges at the ictal Focus occurred less frequently after the stimulation with the intensity of 0.5 mA. With the intensity of 7.5 mA and 2.0 mA, however, habitual auras were elicited by the stimulation, and afterdischarges were seen on the cortical EEG. Conclusions: Low-frequency, low-intensity electric cortical stimulation could produce inhibitory effects on Epileptic activity. At the same time, however, a caution for possible induction of EEG seizures is needed, even when applying low-frequency electric stimulation. Key Words: Low-frequency electric cortical stimulation—Subdural electrode—Intractable epilepsy— Interictal epileptiform discharge—Inhibitory effects.
Elias Ebrahimzadeh - One of the best experts on this subject based on the ideXlab platform.
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quantitative determination of concordance in localizing Epileptic Focus by component based eeg fmri
Computer Methods and Programs in Biomedicine, 2019Co-Authors: Elias Ebrahimzadeh, Mohammad Shams, Farahnaz Fayaz, Lila Rajabion, Mahya Mirbagheri, Babak Nadjar Araabi, Hamid SoltanianzadehAbstract:Abstract Background and objective Accurate seizure onset zone (SOZ) localization is an essential step in pre-surgical assessment of patients with refractory focal epilepsy. Complex pathophysiology of Epileptic cerebral structures, seizure types and frequencies have not been considered as influential features for accurate identification of SOZ using EEG-fMRI. There is a crucial need to quantitatively measure concordance between presumed SOZ and IED-related BOLD response in different brain regions to improve SOZ delineation. Methods A novel component-based EEG-fMRI approach is proposed to measure physical distance between BOLD clusters and selected component dipole location using patient-specific high resolution anatomical images. The method is applied on 18 patients with refractory focal epilepsy to localize Epileptic Focus and determine concordance quantitatively and compare between maximum BOLD cluster with identified component dipole. To measure concordance, distance from a voxel with maximal z-score of maximum BOLD to center of extracted component dipole is measured. Results BOLD clusters to spikes distances for concordant ( 50 mm) groups were significantly different (p Conclusions This study demonstrated that BOLD changes were related to Epileptic spikes in different brain regions in patients with refractory focal epilepsy. In a systematic quantitative approach, concordance levels based on the distance between center of maximum BOLD cluster and dipole were determined by component-based EEG-fMRI method. Therefore, component-based EEG-fMRI can be considered as a reliable predictor of SOZ in patients with focal epilepsy and included as part of clinical evaluation for patients with medically resistant epilepsy.
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component related bold response to localize Epileptic Focus using simultaneous eeg fmri recordings at 3t
Journal of Neuroscience Methods, 2019Co-Authors: Elias Ebrahimzadeh, Babak Nadjar Araabi, Hamid Soltanianzadeh, Seyed Sohrab Hashemi Fesharaki, Jafar Mehvari HabibabadiAbstract:Abstract Background Simultaneous EEG-fMRI experiments record spatiotemporal dynamics of Epileptic activity. A shortcoming of spike-based EEG-fMRI studies is their inability to provide information about behavior of Epileptic generators when no spikes are visible. New method We extract time series of Epileptic components identified on EEG and fit them with Generalized Linear Model (GLM) model. This allows a precise and reliable localization of Epileptic foci in addition to predicting generator's behavior. The proposed method works in the source domain and delineates generators considering spatial correlation between spike template and candidate components in addition to patient's medical records. Results The proposed method was applied on 20 patients with refractory epilepsy and 20 age- and gender-matched healthy controls. The identified components were examined statistically and threshold of localization accuracy was determined as 86% based on Receiver Operating Characteristic (ROC) curve analysis. Accuracy, sensitivity, and specificity were found to be 88%, 85%, and 95%, respectively. Contribution of EEG-fMRI and concordance between EEG and fMRI were also evaluated. Concordance was found in 19 patients and contribution in 17. Comparison with existing methods We compared the proposed method with conventional methods. Our comparisons showed superiority of the proposed method. In particular, when epileptogenic zone was located deep in the brain, the method outperformed existing methods. Conclusions This study contributes substantially to increasing the yield of EEG-fMRI and presents a realistic estimate of the neural behavior of Epileptic generators, to the best of our knowledge, for the first time in the literature.
Hamid Soltanianzadeh - One of the best experts on this subject based on the ideXlab platform.
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quantitative determination of concordance in localizing Epileptic Focus by component based eeg fmri
Computer Methods and Programs in Biomedicine, 2019Co-Authors: Elias Ebrahimzadeh, Mohammad Shams, Farahnaz Fayaz, Lila Rajabion, Mahya Mirbagheri, Babak Nadjar Araabi, Hamid SoltanianzadehAbstract:Abstract Background and objective Accurate seizure onset zone (SOZ) localization is an essential step in pre-surgical assessment of patients with refractory focal epilepsy. Complex pathophysiology of Epileptic cerebral structures, seizure types and frequencies have not been considered as influential features for accurate identification of SOZ using EEG-fMRI. There is a crucial need to quantitatively measure concordance between presumed SOZ and IED-related BOLD response in different brain regions to improve SOZ delineation. Methods A novel component-based EEG-fMRI approach is proposed to measure physical distance between BOLD clusters and selected component dipole location using patient-specific high resolution anatomical images. The method is applied on 18 patients with refractory focal epilepsy to localize Epileptic Focus and determine concordance quantitatively and compare between maximum BOLD cluster with identified component dipole. To measure concordance, distance from a voxel with maximal z-score of maximum BOLD to center of extracted component dipole is measured. Results BOLD clusters to spikes distances for concordant ( 50 mm) groups were significantly different (p Conclusions This study demonstrated that BOLD changes were related to Epileptic spikes in different brain regions in patients with refractory focal epilepsy. In a systematic quantitative approach, concordance levels based on the distance between center of maximum BOLD cluster and dipole were determined by component-based EEG-fMRI method. Therefore, component-based EEG-fMRI can be considered as a reliable predictor of SOZ in patients with focal epilepsy and included as part of clinical evaluation for patients with medically resistant epilepsy.
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component related bold response to localize Epileptic Focus using simultaneous eeg fmri recordings at 3t
Journal of Neuroscience Methods, 2019Co-Authors: Elias Ebrahimzadeh, Babak Nadjar Araabi, Hamid Soltanianzadeh, Seyed Sohrab Hashemi Fesharaki, Jafar Mehvari HabibabadiAbstract:Abstract Background Simultaneous EEG-fMRI experiments record spatiotemporal dynamics of Epileptic activity. A shortcoming of spike-based EEG-fMRI studies is their inability to provide information about behavior of Epileptic generators when no spikes are visible. New method We extract time series of Epileptic components identified on EEG and fit them with Generalized Linear Model (GLM) model. This allows a precise and reliable localization of Epileptic foci in addition to predicting generator's behavior. The proposed method works in the source domain and delineates generators considering spatial correlation between spike template and candidate components in addition to patient's medical records. Results The proposed method was applied on 20 patients with refractory epilepsy and 20 age- and gender-matched healthy controls. The identified components were examined statistically and threshold of localization accuracy was determined as 86% based on Receiver Operating Characteristic (ROC) curve analysis. Accuracy, sensitivity, and specificity were found to be 88%, 85%, and 95%, respectively. Contribution of EEG-fMRI and concordance between EEG and fMRI were also evaluated. Concordance was found in 19 patients and contribution in 17. Comparison with existing methods We compared the proposed method with conventional methods. Our comparisons showed superiority of the proposed method. In particular, when epileptogenic zone was located deep in the brain, the method outperformed existing methods. Conclusions This study contributes substantially to increasing the yield of EEG-fMRI and presents a realistic estimate of the neural behavior of Epileptic generators, to the best of our knowledge, for the first time in the literature.
Riki Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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high frequency activity overriding cortico cortical evoked potentials reflects altered excitability in the human Epileptic Focus
Clinical Neurophysiology, 2017Co-Authors: Katsuya Kobayashi, Riki Matsumoto, Masao Matsuhashi, Kiyohide Usami, Akihiro Shimotake, Takeharu Kunieda, Takayuki Kikuchi, Kazumichi Yoshida, Nobuhiro MikuniAbstract:Abstract Objective We aimed to clarify that high frequency activity (HFA) of cortico-cortical evoked potentials (CCEPs), elicited by single pulse electrical stimulation (SPES), reflects cortical excitability. Methods We recruited 16 patients with refractory partial epilepsy who had chronic subdural electrode implantation for presurgical evaluation. A repetitive SPES was given to (1) the seizure onset zone (SOZ) and (2) the control cortices (non-seizure onset zone: nSOZ). CCEPs were recorded from the neighboring cortices within SOZ and nSOZ. We applied short-time Fourier transform to obtain the induced responses for the timing of early ( 200 Hz) bands. Results Twenty-one clear CCEPs were recorded for both the SOZ and nSOZ. The HFA power of early CCEPs in SOZ significantly increased compared to that in nSOZ in both frequency bands, particularly in mesial temporal lobe epilepsy (MTLE). Conclusion Similar to the features of spontaneous pathological HFOs, the power of stimulus-induced HFAs in SOZ were greater than that outside SOZ, particularly in MTLE. Significance HFA overriding CCEPs can be a surrogate marker of cortical excitability in Epileptic Focus.
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o1 e 9 hfo correlates of cortico cortical evoked potentials reveal altered excitability in the human Epileptic Focus
Clinical Neurophysiology, 2013Co-Authors: Katsuya Kobayashi, Riki Matsumoto, Hidenao Fukuyama, Nobuhiro Mikuni, Masao Matsuhashi, Kiyohide Usami, Akihiro Shimotake, Takeharu Kunieda, Susumu Miyamoto, Ryosuke TakahashiAbstract:By using cortico-cortical evoked potentials [CCEP: early negative (N1) and late negative (N2) components], we aimed to clarify high frequency oscillation (HFO) correlates of CCEPs and its relation to human epileptogenesis. We recruited 12 patients with intractable partial epilepsy who underwent invasive presurgical evaluation with chronic implantation of subdural electrodes. Repetitive single-pulse electrical stimulation (1 Hz) was applied to (1) the seizure onset zone (SOZ) and (2) the control cortex (nSOZ), and CCEPs were recorded from the surrounding cortices within SOZ and nSOZ, respectively. We applied short-time Fourier transform to obtain induced responses at the timing of N1 (HFON1) and N2 (HFON2) and analyzed the logarithmic power change of HFON1 and HFON2 in reference to the baseline activity for ripple (120–200 Hz) and fast ripple (>200 Hz) bands. Seventeen clear CCEP responses were recorded for both SOZ and nSOZ across patients. In both SOZ and nSOZ stimulation, HFON1 generally showed power increase and HFON2 power decrease across the 2 frequency bands. HFON1 power at SOZ increased more significantly than that at nSOZ in FR band. The present study suggests HFO correlates of CCEPs could be a surrogate marker of abnormally enhanced cortical excitability in human Epileptic Focus.
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Usefulness of MEG magnetometer for spike detection in patients with mesial temporal Epileptic Focus
NeuroImage, 2008Co-Authors: Rei Enatsu, Junya Taki, Tahamina Begum, Takashi Nagamine, Riki Matsumoto, Akio Ikeda, Nobuhiro Mikuni, Jun Matsubayashi, Keiko Usui, Hidenao FukuyamaAbstract:Abstract The present study investigated the sensitivity of magnetoencephalography (MEG) for spikes depending on sensor type in patients with mesial temporal Epileptic Focus. We recorded MEG in 6 patients with mesial temporal Epileptic Focus using two sensor types (magnetometer and gradiometer) simultaneously. The number of spikes detected and the corresponding equivalent current dipole (ECD) parameters (distance from the coordinated head center (radius), and dipole moment) were evaluated with respect to sensor type. Among 426 MEG ‘consensus spikes’ determined by 3 reviewers, 378 spikes satisfied the predetermined criteria for source localization. Comparing ECD parameters, spikes detected by magnetometer alone displayed a smaller radius and larger dipole moment than those detected by gradiometer alone. Spikes estimated in the mesial temporal area were more frequently detected by magnetometer alone (38.5%) than by gradiometer alone (11.5%), whereas spikes in the lateral temporal area were detected less by magnetometer alone (3.7%) than by gradiometer alone (53.9%). The present results suggest that a magnetometer is advantageous for spike detection in patients with mesial temporal Epileptic Focus. This also implies the higher sensitivity of magnetometer for deep sources.
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low frequency electric cortical stimulation has an inhibitory effect on Epileptic Focus in mesial temporal lobe epilepsy
Epilepsia, 2002Co-Authors: Junichi Yamamoto, Riki Matsumoto, Akio Ikeda, Nobuhiro Mikuni, Takeshi Satow, Kazuhide Takeshita, Motohiro Takayama, Masao Matsuhashi, Shinji Ohara, Jun TakahashiAbstract:Summary: Purpose: This study was conducted to investigate the effect of low-frequency electric cortical stimulation on Epileptic Focus in humans. Methods: We stimulated the Epileptic Focus in a patient with medically intractable mesial temporal lobe epilepsy (MTLE) by means of subdural electrodes and evaluated the change in the number of interictal epileptiform discharges. We used biphasic electric current of 0.3-ms duration presented at 0.9-Hz frequency for 250 s, comparing stimulus intensity of 7.5, 2, and 0.5 mA. Results: Interictal epileptiform discharges at the ictal Focus occurred less frequently after the stimulation with the intensity of 0.5 mA. With the intensity of 7.5 mA and 2.0 mA, however, habitual auras were elicited by the stimulation, and afterdischarges were seen on the cortical EEG. Conclusions: Low-frequency, low-intensity electric cortical stimulation could produce inhibitory effects on Epileptic activity. At the same time, however, a caution for possible induction of EEG seizures is needed, even when applying low-frequency electric stimulation. Key Words: Low-frequency electric cortical stimulation—Subdural electrode—Intractable epilepsy— Interictal epileptiform discharge—Inhibitory effects.