Motion-onset related components in averaged whole head co-recorded MEG and EEG responses of 24 adults to a low-contrast checkerboard pattern were studied. The aims were to identify these components, to characterize quantitatively their maps and to localize the underlying sources by equivalent-current-dipole (ECD) analyses with a spherical head model.After a weak P1, a large start-elicited negat...

Numerous studies of the somatosensory evoked field (SEF) have confirmed the homuncular organization of the first somatosensory cortex (SI) [1, 2]. A dipole source analysis of SEFs recorded near the surface of the head allows to localize the underlying neural generators in SI and in the secondary somatosensory cortex (SII) [3, 4]. Theoretical as well as experimental studies suggest that sources ...

This study combines source analysis imaging data for early somatosensory processing and the probabilistic cytoarchitectonic maps (PCMs). Human somatosensory evoked fields (SEFs) were recorded by stimulating left and right median nerves. Filtering the recorded responses in different frequency ranges identified the most responsive frequency band. The short-latency averaged SEFs were analyzed usin...

The analysis of epileptic discharges in magnetoencephalography with minimum norm estimates (MNE) is expected to provide more precise localization of epileptic discharges compared with electroencephalographic estimations. However, the clinical feasibility of MNE remains unclear. In this study, we aimed to elucidate the onset and propagation patterns of interictal spikes using MNE. Seven patients...

It is difficult to perform ictal vs. interictal MEG localization studies. MEG recordings of epileptic seizures are rare and are often accompanied by patient movements. However, during routine MEG recordings of a presurgical patient with epilepsy, a complex partial seizure was recorded with a whole head neuromagnetometer (4D Neuroimaging Magnes WHS2500). During seizure, the patient opened his ey...

The present study used magnetoencephalography (MEG) to examine perceptual learning of American English /r/ and /l/ categories by Japanese adults who had limited English exposure. A training software program was developed based on the principles of infant phonetic learning, featuring systematic acoustic exaggeration, multi-talker variability, visible articulation, and adaptive listening. The pro...

Magnetoencephalography (MEG) is a non-invasive functional imaging modality based on the measurement of the external magnetic field produced by neural current sources within the brain. The reconstruction of the underlying sources is a severely ill-posed inverse problem typically tackled using either low-dimensional parametric source models, such as an equivalent current dipole (ECD), or high-dim...

It is difficult to perform ictal vs. interictal MEG localization studies. MEG recordings of epileptic seizures are rare and are often accompanied by patient movements. However, during routine MEG recordings of a presurgical patient with epilepsy, a complex partial seizure was recorded with a whole head neuromagnetometer (4D Neuroimaging Magnes WHS2500). During seizure, the patient opened his ey...

Over the last years, highly sensitive magnetic field sensors, SQUIDs, have been employed to measure the magnetocardiogram (MCG), which are generated by ionic currents flowing in myocardium when it is active. The MCG method provides additional information in comparison to surface electric potential distribution. The obtained information is complementary in nature because the magnetic field is re...

OBJECTIVE The possibility of simultaneously observing activation of primary and secondary auditory cortices has been demonstrated by Engelien et al. [Hear Res 2000;148:153-60]. METHODS Such a dual monitoring by means of neuromagnetic recordings can be achieved when a subject is stimulated by brief pulses of 40Hz-modulated tones. Depending on the frequency filter applied, either the steady-sta...