OBJECTIVE To assess the clinical value of magnetoencephalography (MEG) in localising the primary hand motor area and evaluating cortical distortion of the sensorimotor cortices in patients with intracerebral tumour. METHODS 10 normal volunteers (controls) and 14 patients with an intracerebral tumour located around the central region were studied. Somatosensory evoked magnetic fields (SEFs) fo...

1 Introduction Equivalent current dipole (ECD) analysis for mag-netoencephalogram (MEG) has been useful in screening the localization of the epileptogenic zone, even though MEG was recorded in the interictal period [1] [2]. However, it requires several mathematical restrictions and often fails to estimate confidential current sources. Therefore the epileptogenic area derived from the ECD analys...

Somatosensory evoked fields (SEFs) to electrical stimulation on the right and left sides of the lower lip were measured using magnetoencephalography and compared in the bilateral hemispheres of 31 healthy normal young and 29 healthy normal elderly subjects to evaluate age-related change in lip somatosensation. The initial peak of the response around 13 ms, designated as N13m, and the second pea...

Source estimates performed using a single equivalent current dipole (ECD) model for interictal epileptiform discharges (IEDs) which appear unifocal have proven highly accurate in neocortical epilepsies, falling within millimeters of that demonstrated by electrocorticography. Despite this success, the single ECD solution is limited, best describing sources which are temporally stable. Adapted fr...

This paper describes an application of hierarchical or empirical Bayes to the distributed source reconstruction problem in electro- and magnetoencephalography (EEG and MEG). The key contribution is the automatic selection of multiple cortical sources with compact spatial support that are specified in terms of empirical priors. This obviates the need to use priors with a specific form (e.g., smo...

The excitability of the cerebral cortex in the interictal state of migraine appears to be fundamental in the brain's susceptibility to migraine attacks. Subpopulations of cortical neurons are reported to have different physiological response properties to different interstimulus intervals (ISIs) and, hence, may be differentially altered or modulated in migraine. The aim of this study therefore ...

The M100 wave representing a robust component of cortical Auditory Evoked Magnetic Fields (AEFs) is used to localize neuronal activation in the primary auditory cortex for a long time in neurophysiological research and with increasing importance also in clinical research [1-4]. Changes of location, orientation and strenght of equivalent current dipoles (ECD) are considered being correlated to c...

The excellent temporal resolution of magnetoencephalography (MEG) is universally acknowledged, but the accuracy of its source estimation is often questioned on theoretical and practical grounds. Here, we evaluate the localization accuracy of MEG for four widely used source modeling techniques (Equivalent Current Dipole (ECD), Synthetic Aperture Magnetometry (SAM), MUltiple SIgnal Classification...

This chapter will propose a new paradigm for single-trial-electroencephalogram (EEG)-based Brain-Computer Interfaces (BCIs) with motor imagery (MI) [1] tasks. Among such BCIs, the sensorimotor rhythm (SMR)-based ones, when using common spatial patterns (CSPs), require features over broad frequency bands, such as mu, beta and gamma rhythms [2]. Therefore, very high-dimensional feature vectors an...

A brief review of previous studies is presented on tonotopic organization of primary auditory cortex (AI) in humans. Based on the place theory for pitch perception, in which place information from the cochlea is used to derive pitch, a well-organized layout of tonotopic map is likely in human AI. The conventional view of tonotopy in human AI is a layout inwhich the medial-to-lateral portion of ...