MR-Compatible dEEG

Recent advances have allowed dense array EEG (128 and 256 channels) to be recorded in the MRI environment with good signal quality (for both EEG and MR data) for the first time. In this 256-channel MR-compatible Geodesic Sensor Net, the sensor pedestals contain miniature printed circuit boards for lead microconnections and the integral safety resistor.

With careful design for both safety and signal quality, EGI's MR-compatible dEEG system allows dEEG to become a routine procedure to optimize the data yield for the investment in fMRI studies.

Two-way isolation (of the Net Amps 300 from the MR fields and the MR from the NA300 fields) is provided by the Field Isolation-Containment System (FICS).

In an EGI research project on how Imagery Analyst experts detect military targets in satellite images, event-related fMRI measures (red) showed that activity in inferior temporal and posterior cingulate regions was greater for targets versus non-targets. This research was funded by the US Defense Advanced Research Projects Agency and is currently funded by the National Geospatial-Intelligence Agency.

In the same DARPA-NGA visual target detection study, dEEG results showed source localization to inferior temporal and posterior cingulate regions, but also activity (peaking at 250-300 ms) in the temporal lobe that was not seen in the hemodynamic fMRI results. Results during non simultaneous recordings such as these suggest that comparing dEEG with fMRI results will be both important and challenging. Careful comparisons of these measures will require simultaneous recordings.