The advances in electronics shielding and isolation of the field isolation containment system (FICS) have also been applied to allow 256-channel dEEG to be recorded in the MEG room, with no degradation of MEG quality. EGI's introduction of MR- and MEG-compatible dEEG systems with the FICS technology now provides a technology bridge between the spatial resolution of fMRI studies and the temporal resolution of MEG studies.
Early studies with 256-channel EEG and MEG from 4D neuroimaging showed the expected orthogonal orientations of the electrical and magnetic fields. Analysis of these data showed that 256-channel EEG provided localization of the somatosensory event-related potential that was equal to or better than that provided by whole-head MEG.
Dense array EEG and MEG may be seen as competitive, but it is clear that when combined effectively they are synergistic. Simulation studies conducted by scientists at EGI and Los Alamos National Laboratory (LANL) have shown that joint dEEG-MEG recordings greatly improve localization precision. EEG and MEG fields are complementary, thus the improvement is more than additive, and can be described as truly synergistic.
Klamer et al. from the University of Tübingen, have published a report in Brain Topography
directly comparing high-channel-count MEG to EGI's high-channel-count EEG. The authors compared source localizations from a 275-channel MEG system and an EGI 256 channel EEG system to anatomical reference points obtained with fMRI. While MEG was able to provide more accurate source localizations than EEG using a generic head model, EEG using individual head models produced the most accurate source localizations. See the original paper.
EGI's new MicroCel Geodesic Sensor Nets (GSN) are designed specifically for low-profile applications like simultaneous EEG-MEG. With sensor pedestals only 4.5 mm tall, the MicroCel fits more easily into the MEG dewar than typical EEG sensor caps.
For several years, EGI and LANL scientists have collaborated in simultaneous dEEG-MEG research. This research combined MEG-compatible dEEG prototypes with the advanced Superconducting Imaging Surface (SIS) MEG system at LANL.
With the introduction of EGI's FICS MR-compatible dEEG system and Geodesic Sensor Nets, EGI's dEEG is now compatible with all commercial MEG systems.