At the sensor level many aspects, such as spectral power, functional and effective connectivity as well as relative-power-ratio ratio (RPR) and spatial resolution have been comprehensively investigated through both electroencephalography (EEG) and magnetoencephalography (MEG). Despite this, differences between both modalities have not yet been systematically studied by direct comparison. It rem...

OBJECTIVE: Many studies of dementia mainly Alzheimer's disease (AD) by using MEG have been reported. Some results show there are some differences between patients and controls in MEG data. But it is still difficult to diagnose the disease in early stage using their methods because of large individual variation. We measured many patients and normal aged subjects, and extracted various parameters...

Neuro-electromagnetic recording techniques (EEG, MEG, iEEG) provide high temporal resolution data to study the dynamics of neurocognitive networks: large scale neural assemblies involved in task-specific information processing. How does a neurocognitive network reorganize spatiotemporally on the order of a few milliseconds to process specific aspects of the task? At what times do networks segre...

The inverse problem in Electroand Magneto-EncephaloGraphy (EEG/MEG) aims at reconstructing the underlying current distribution in the human brain using potential differences and/or magnetic fluxes that are measured non-invasively directly, or at a close distance, from the head surface. The solution requires repeated computation of the forward problem, i.e., the simulation of EEG and MEG fields ...

Imaging the dynamics of distributed phase synchrony across brain signals is of crucial importance for the study of large-scale interactions in the brain, and requires combining at the same time, wide coverage of the brain with high spatial and temporal resolution. Electroand magneto-encephalography (EEG–MEG), which provide full head coverage measurements of the human brain activity, can potenti...

Magnetoencephalography (MEG) detects the brain's magnetic fields as generated by neuronal electric currents arising from synaptic ion flow. It is noninvasive, has excellent temporal resolution, and it can localize neuronal activity with good precision. For these reasons, many scientists interested in the localization of brain functions have turned to MEG. The technique, however, is not without ...

Letter-perception centers are not held in as high regard as motor- and language-related cortices during planning of neurosurgical procedures, and there have been no reports suggesting cortical reorganization of reading ability. The authors describe a patient with a left mesial temporal glioma in whom two letter-perception centers (the anterior portion of the left superior temporal gyrus and the...

Magnetic source imaging using a whole-head MEG system provides a more accurate localization of epileptic focus than other routinely used noninvasive methods such as scalp video EEG and magnetic resonance imaging (MRI) [1-3]. However, MEG source localization, as estimated by the single dipole and spherical model, may not fully describe an epileptic region that includes extensive or multiple epil...

DNA methylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) are potent carcinogens; their carcinogenic effect is mainly due to the effect of production of O6-methylguanine (O6 MeG) on DNA. O6 MeG is not only mutagenic but also toxic to the cell because Mer-/Mex- cells unable to remove O6 MeG are very sensitive to killing by MNNG. It has been proposed that repeated futile mismatch...

Source localizations based on EEG and MEG show different accuracies. One of the major differences between EEG and MEG localization is that the former depends on electrical tissue conductivities. It is hypothesized that an incorrect assumption of the skull conductivity value is a major contributor to EEG inaccuracy. In a simulation study, it is shown that assuming single skull conductivity for a...