Journal ArticleDOI
Pattern recognition in biomagnetic signals by spatio-temporal correlation and application to the localisation of propagating neuronal activity.
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TLDR
The recognition and subsequent averaging of spike events in the MEG of an epileptic patient by this method is shown to provide an essential improvement in the signal-to-noise ratio.Abstract:
A combined correlation analysis of temporal and spatial patterns in a biomagnetic multichannel recording is proposed to extract patterns of transient, randomly repetitive physiological events from biomagnetic data sets with a low signal-to-noise ratio. This method is especially sensitive in the differentiation of signals from different source propagation pathways. The recognition and subsequent averaging of spike events in the MEG of an epileptic patient by this method is shown to provide an essential improvement in the signal-to-noise ratio. The source localisation from the averaged data showed electrical activity which propagated from the primary epileptogenic focus to distant parts of the brain.read more
Citations
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Journal ArticleDOI
Ictal and interictal activity in partial epilepsy recorded with multichannel magnetoelectroencephalography: correlation of electroencephalography/electrocorticography, magnetic resonance imaging, single photon emission computed tomography, and positron emission tomography findings.
Hermann Stefan,S. Schneider,H. Feistel,G. Pawlik,P. Schüler,Klaus Abraham-Fuchs,T Schlegel,Neubauer U,Walter J. Huk +8 more
TL;DR: Ictal and interictal epileptic activity was recorded for the first time by multichannel magnetoencephalography (MEG) in three patients with partial epilepsy and main zones of ictal activity were shown to evolve from the tissue at the centers of interictAL activity.
Journal ArticleDOI
Multiple Olfactory Activity in the Human Neocortex Identified by Magnetic Source Imaging
TL;DR: For the first time, brain areas were identified that generate most components of olfactory bioresponses (OERPs) in humans.
Journal ArticleDOI
Event-synchronous cancellation of the heart interference in biomedical signals
TL;DR: A two-pass adaptive filtering algorithm is proposed for cancellation of recurrent interferences such as the heart interference in biomedical signals and to the effective isolation of ventricular extrasystoles in magnetocardiogram signals.
Journal ArticleDOI
Magnetic source localization and morphological changes in temporal lobe epilepsy: comparison of MEG/EEG, ECoG and volumetric MRI in presurgical evaluation of operated patients.
Hermann Stefan,P. Schüler,Klaus Abraham-Fuchs,S. Schneider,Matthias Gebhardt,U. Neubauer,Cornelia Hummel,W. J. Huk,P. Thierauf +8 more
TL;DR: It is concluded that magnetic source analysis provides 3D information concerning spatial correlation of lesion and irritative zone in temporal lobe epilepsy, very important for planning invasive recordings and selective surgical procedures.
Journal ArticleDOI
Magnetic field tomography of cortical and deep processes: examples of "real-time mapping" of averaged and single trial MEG signals.
TL;DR: MFT analysis of averaged auditory "odd-ball" data show cortical and deep activation, presumably from the amygdala and hippocampus, which are compared with MFT estimates obtained from a patient who had undergone lobectomy which removed these structures.
References
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Journal ArticleDOI
Realistic conductivity geometry model of the human head for interpretation of neuromagnetic data
Matti Hämäläinen,Jukka Sarvas +1 more
TL;DR: A method to handle the numerical difficulties caused by the presence of poorly conducting skull is presented and it is shown numerically that for the computation of B produced by cerebral current sources, it is sufficient to consider a brain-shaped homogeneous conductor only.
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Tonotopic organization of the human auditory cortex
TL;DR: Neuromagnetic measurements of responses to auditory stimuli consisting of pure tones amplitude-modulated at a low frequency have been used to deduce the location of cortical activity.
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Mathematical dipoles are adequate to describe realistic generators of human brain activity
TL;DR: It is found that the deviation between the positions of the disks and annuli and the equivalent dipole is very small, and the differences in the direction and amplitude may be neglected.
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Neuromagnetic Evidence of Spatially Distributed Sources Underlying Epileptiform Spikes in the Human Brain
TL;DR: Neuromagnetic measurements were performed on 17 subjects with focal seizure disorders and the interictal spike in the scalp electroencephalogram was associated with an orderly extracranial magnetic field pattern.
Journal ArticleDOI
Spatial resolution of neuromagnetic records: theoretical calculations in a spherical model.
TL;DR: Spatial resolution of magnetoencephalography was studied by computer simulations using a spherical conductor model for the head to illustrate the dependence of spatial resolution on several factors including noise, source depth, source strength, flux transformer configuration and the choice of the measurement locations.