Ralf Drenckhahn

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An improved boundary element method (BEM) with a virtual triangle refinement using the vertex normals, an optimized auto solid angle approximation, and a weighted isolated problem approach is presented. The performance of this new approach is compared to analytically solvable spherical shell models and highly refined reference BEM models for tangentially(More)
OBJECTIVES A framework for combining bioelectric and biomagnetic data is presented. The data are transformed to signal-to-noise ratios and reconstruction algorithms utilizing a new regularization approach are introduced. METHODS Extensive simulations are carried out for 19 different EEG and MEG montages with radial and tangential test dipoles at different(More)
Source localizations of early somatosensory evoked potentials and electrical potentials produced by dipoles in the region of the central sulcus were computed using realistically shaped boundary-element head models (BEM) and compared to localizations obtained using 3-shell spherical models. Realistically shaped 3-shell boundary-element-models were(More)
The source of the radial field of P22 was previously attributed either to the precentral (area 4) or postcentral (area 1) gyrus, on the basis of interpretation of potential maps recorded on the skin or cortex, respectively. The present study used dipole localization within realistically shaped head models and constrained the inverse solution by using the(More)
Neurophysiological activity, as measured with EEG or MEG, has its origin in the brain. For most EEG and MEG experiments it is known beforehand, that the folded gray matter of the cortex is the location of the neurons whose activity is measured. These neurons, the pyramidal cells, are oriented perpendicular to the cortical surface. Triangulation of the(More)
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