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Clin EEG Neurosci [journal]
- Motor Imagery EEG Discrimination Using the Correlation of Wavelet Features. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Mar 5.
A novel method for motor imagery (MI) electroencephalogram (EEG) data classification is proposed in this study. Time-frequency representation is constructed by means of continuous wavelet transform from EEG signals and then weighted with 2-sample t-statistics, which are also used to automatically select the area of interest in advance. Finally, normalized cross-correlation is used to discriminate the test MI data. Compared with the nonweighted version on MI data, the experimental results indicate that the proposed system achieves satisfactory results in the applications of brain-computer interface (BCI).
- Phase Synchronization and Spectral Coherence Analysis of EEG Activity during Mental Fatigue. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Mar 3.
In this article, 2 synchronization measures, phase locking value (PLV) and spectral coherence value (SCV), are used to characterize the changes of the phase synchronization and functional coupling of electroencephalogram (EEG) waves at different brain cortical areas for mental fatigue caused by a long-term cognitive task. The long-term cognitive task induces a significant decrease in the interhemispheric SCVs and PLVs of beta in central and parietal regions, a significant decrease in the intrahemispheric SCVs and PLVs of beta frequency band at the frontal-parietal and central-parietal, and frontal-central middle electrode pairs, suggesting EEG decreases in cooperative processing, strength of functional coupling, and flux of mutual information exchange in the corresponding inter- and intrahemispheres. However, when the mental fatigue level increases, the interhemispheric PLVs of theta are enhanced in the frontal region and C3-Cz electrode pair, and the intrahemispheric PLVs of theta are heightened at frontal-central middle electrode pairs. PLV and SCV measures could reflect the changes of the phase synchronization and functional coupling of EEG waves from time and frequency domains, which are sensitive to mental fatigue. Therefore, PLVs and SCVs can provide an effective and reliable way to quantify brain response to mental fatigue.
- Periodic Lateralized Epileptiform Discharges Associated With Irreversible Hyperglycemic Hemichorea-Hemiballism. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Mar 3.
Periodic lateralized epileptiform discharges (PLEDs) on electroencephlography (EEG) usually indicate an acute, diffuse, and severe cerebral insult. Although hyperglycemic hemichorea-hemiballisum (HCHB) and striatal hyperintensity on T1-weighted magnetic resonance (MR) images is an accepted clinical entity, PLEDs have not previously been reported. Herein, we report a 74-year-old man with hyperglycemic HCHB, hyperintense putamen on T1-MR images and PLEDs on EEG. Aggressive sugar control with neuroleptic treatment only slightly improved the severity of HCHB. We also tried titrated oral and intravenous haloperidol, clonazepam, and propranolol sequentially and in combination; however, the effects were poor. Unlike the generally reversibility of hyperglycemic HCHB, the condition was still present 6 months later. Hyperglycemia can cause HCHB and produce subcortical type-PLEDs, which may explain the findings in our patient. In conclusion, PLEDs can be found in patients with hyperglycemic HCHB and striatal hyperintensity on T1-weighted MR images, and the appearance of PLEDs may indicate an irreversible outcome. EEG should be considered in such circumstances.
- LORETA Neurofeedback in the Precuneus: Operant Conditioning in Basic Mechanisms of Self-Regulation. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Mar 3.
Low-resolution brain electomagnetic tomography (LORETA) neurofeedback provides a mechanism to influence the electrical activity of the brain in intracranial space. The aim of this study was to determine the effects of LORETA neurofeedback (LNFB) in the precuneus as a mechanism for improving self-regulation in controls and a heterogeneous diagnostic group (DX). Thirteen participants completed between 10 and 20 sessions of LNFB training in a 3-voxel cluster in the left precuneus. The participants included 5 nonclinical university students, and 8 adults with heterogeneous psychiatric diagnoses. We assessed the effects of LNFB with neurophysiological measures as well as pre- and post-Personality Assessment Inventory (PAI) subscales and selected subtests from the Delis-Kaplan Executive Function System (DKEFS). There was a significant total relative power increase at the precuneus for baseline contrasts for the control group. The DX group did not reach significant levels. All participants showed improvements in executive functions and tended to report significantly less psychopathology. The basic neural mechanisms of self-regulation are poorly understood. The data obtained in this study demonstrate that LNFB in a heterogeneous population enhances executive functions while concordantly decreasing endorsement of psychological symptoms. The alpha frequency in the brain may represent integrative functioning relative to operant efficiency and self-regulatory mechanisms.
- EEG Synchronization Evaluation: A New Diagnostic Tool for Predicting the Progression of Alzheimer's disease. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Mar 3.
Alzheimer's disease (AD) is known as a leading cause of dementia in elderly persons. It is a chronic neurodegenerative disorder characterized by progressive cognitive dysfunction. AD can disrupt functional connectivity in distributed cortical networks. The S-estimator, which is a measure of multivariate intraregional synchronization, was analyzed in this study. Twenty patients with AD and 20 age-matched controls were tested at baseline and after 1 year to evaluate the potential of synchronization to be a possible marker of AD progression. All the subjects had clinical evaluations and electroencephalography (EEG) at baseline and post 1 year. Hyposynchronization had an important effect in the medial temporal and frontal regions, while there were no significant effects for hypersynchronization. Hypersynchronized clusters changed more slowly with time (P = .067), whereas hyposynchronized clusters changed more quickly (P = .032). Hyposynchronized cluster-averaged S-estimator correlated negatively with progression of AD (r = -0.98769, P = .0103). In conclusion, the present study provides a whole-brain, AD-specific phenotype of temporal coordination in distributed cortical networks, which is an early diagnostic tool for progression of AD.
- Epileptiform Discharges and Frontal Paroxysmal EEG Abnormality Act as Predictive Marker for Subsequent Epilepsy in Children with Complex Febrile Seizures. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Feb 28.
Using electroencephalography (EEG) for diagnosing subsequent epilepsy in children after febrile seizure (FS) is not common. The present study investigates the relationship between epileptiform discharges and subsequent epilepsy, and looks for the predictive marker for this disorder. A total of 378 children with complex FS and whose EEG showed epileptiform discharges or normal EEG were included. Development of FS was compared between those with epileptiform discharges and those with normal EEG. Risk factors were analyzed using multivariate logistic regression to clarify their effects on subsequent epilepsy. The association between generalized or focal EEG localization, and between frontal epileptiform discharges and subsequent epilepsy, were analyzed. Among 378 patients with complex FS, 51 showed epileptiform discharges. History of epilepsy, frontal seizure, number of FS, and prolonged seizure were the risk factors for epileptiform discharge. Subsequent epilepsy was significantly frequent in patients with more than 2 risk factors (odds ratio [OR] = 17; 95% confidence interval [CI] = 4.1-29.6). Prolonged seizure (OR = 4.98; 95% CI = 1.63-13.29), FS number (OR = 2.96; 95% CI = 1.23-10.51), and family history of epilepsy (OR = 2.67; 95% CI = 1.05-7.63) were significantly correlated with subsequent epilepsy. Of 9 patients with paroxysms in the frontal region, 8 (88.9%) developed epilepsy. There was concordance between frontal epileptiform discharges and subsequent epilepsy (κ = .901). In conclusion, epileptiform discharges are risk factors for subsequent epilepsy. Frontal paroxysmal EEG is a marker for subsequent epilepsy.
- Combined use of Multiple Computational Intracranial EEG Analysis Techniques for the Localization of Epileptogenic Zones in Lennox-Gastaut Syndrome. [JOURNAL ARTICLE]
- Clin EEG Neurosci 2014 Feb 18.
Traditionally, identification of epileptogenic zones primarily relied on visual inspection of intracranial electroencephalography (iEEG) recordings by experienced epileptologists; however, removal of epileptogenic zones identified by iEEG does not always guarantee favorable surgical outcomes. To confirm visual inspection results, and assist in making decisions about surgical resection areas, computational iEEG analysis methods have recently been used for the localization of epileptogenic zones. In this study, we have proposed a new approach for the localization of epileptogenic zones in Lennox-Gastaut syndrome (LGS), and have investigated whether the proposed approach could confirm surgical resection areas and predict seizure outcome before surgery. The proposed approach simultaneously used results of 2 iEEG analysis methods, directed transfer function (DTF) and time delay estimation, to enhance localization accuracy. This new combined method was applied to patients who became seizure-free after resective epilepsy surgery, as well as those who had unsuccessful surgery. A quantitative metric was also introduced that can measure how well the localized epileptogenic zones coincided with the surgical resection areas, with the aim of verifying whether the approach could confirm surgical resection areas determined by epileptologists. The estimated epileptogenic zones more strongly coincided with surgical resection areas in patients with successful, compared to those with unsuccessful surgical outcomes. Both qualitative and quantitative analyses showed that the combined use of 2 iEEG analyses resulted in a more accurate estimate of epileptogenic zones in LGS than the use of a single method. A combination of multiple iEEG analyses could not only enhance overall accuracy of localizing epileptogenic zones in LGS, but also has the potential to predict outcomes before resective surgery.
- Corrigendum. [Journal Article]
- Clin EEG Neurosci 2014 Jan; 45(1):61.
Gilles van Luijtelaar, Evgenia Sitnikova and Annika Lüttjohann. On the Origin and Suddenness of Absences in Genetic Absence Models. CLINICAL EEG and NEUROSCIENCE. 2011; 42(2): 83-97. (Original doi: 10.1177/155005941104200209).
- Book review: handbook of quantitative electroencephalography and EEG biofeedback: scientific foundations and practical applications. [Journal Article]
- Clin EEG Neurosci 2014 Jan; 45(1):59-60.
- Consciousness and unconsciousness: an EEG perspective. [Journal Article]
- Clin EEG Neurosci 2014 Jan; 45(1):4-5.