Hyukchan Kwon

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We carried out an magnetoencephalography (MEG) study to record cortical responses elicited in the left hemisphere by ending verb phrases, which had syntactic or semantic anomalies, in Korean sentences of subject-object-verb order. Using the high temporal and spatial resolution of MEG, the study was aimed at identifying neural activities that occur during a(More)
To validate newly developed methods or implemented software for magnetoencephalography/electroencephalography (MEG/EEG) source localization problems, many researchers have used human skull phantom experiments or artificially constructed forward data sets. Between the two methods, the use of an artificial data set constructed with forward calculation attains(More)
BACKGROUND AND PURPOSE The aim of this study was to determine the usefulness of three-dimensional (3D) scalp EEG source imaging (ESI) in partial epilepsy in comparison with the results of presurgical evaluation, magnetoencephalography (MEG), and electrocorticography (ECoG). METHODS The epilepsy syndrome of 27 partial epilepsy patients was determined by(More)
To study the relationship between the varying degrees of cognitive load and long-range synchronization among neural networks, we utilized a dual-task paradigm combining concurrent word recall working memory tasks and oculomotor tasks that differentially activate the common frontoparietal (FP) network. We hypothesized that each dual-task combination would(More)
SUMMARY Multichannel superconducting quantum interference device (SQUID) systems based on double relaxation oscillation SQUIDs (DROS) were developed for measuring magnetocardiography (MCG) and magnetoencephalography (MEG) signals. Since DROS provides large flux-to-voltage transfer coefficients, about 10 times larger than the DC SQUIDs, direct readout of the(More)
We propose independent component analysis (ICA) as a pre-process for synthetic aperture magnetometry (SAM) in magnetocardiogram. SAM is a very useful method for source current imaging. However, SAM cannot separate one source from the others when there are time-correlated multi-sources, especially for successively active sources. The proposed method(More)
Phase-amplitude coupling (PAC) plays an important role in neural communication and computation. Interestingly, recent studies have indicated the presence of ubiquitous PAC phenomenon even during the resting state. Despite the importance of PAC phenomenon, estimation of significant physiological PAC is challenging because of the lack of appropriate surrogate(More)
BACKGROUND Connectivity analysis in magnetoencephalography (MEG) sensor space is commonly used for the preliminary estimation of the functional relationship between cortical areas, but the results are difficult to interpret due to the field spread effect. To improve the interpretability of sensor-level connectivity analysis, we introduce and test a new(More)
Every day, we face situations that involve multi-tasking. How our brain utilizes cortical resources during multi-tasking is one of many interesting research topics. In this study, we tested whether a dual-task can be differentiated in the neural and behavioral responses of healthy subjects with varying degree of working memory capacity (WMC). We combined(More)
A 3-D cardiac visualization is significantly helpful toward clinical applications of magnetocardiography (MCG), but the cardiac reconstruction requires a segmentation process using additional image modalities. This paper proposes a 3-D cardiac outline reconstruction method using only MCG measurement data without further imaging techniques. The cardiac(More)