ActiveOne measures EEG simultaneous with fMRI.
A special version of the ActiveOne system has been modified to be used to measure EEG in the MRI. With only a few modifications the system is suitable for this application. The ActiveOne offers the possibility to use a single system for normal research, and with some minor modifications for measurements inside the MRI. So this makes the ActiveOne a very cost effective solution for expanding your EEG measurements to the MRI.
This MRI version of the ActiveTwo is at this moment still under development and therefore not yet available.
The modifications needed for use in the MRI consist of:
Special carbon-wire electrode set (passive electrodes in standard pin housing)
Specially adapted MRI bufferbox with proprietary input filtering.
Additional shielding box for the standard ActiveOne AD-box and battery.
The special electrodes set in combination with input filtering ensured fully adequate rejection of the large high frequency interference found in the MRI. (This interference is also present between the actual scans).

Because the ActiveOne can operate in DC-mode, the gradient switching during the actual scan did not cause any baseline shifting. As you can see from the picture, clean EEG signals can be measured immediately after the scan stops. The large peaks during the actual scan are still visible in this screenshot of the raw EEG signals. This interference can be rejected with additional off-line software processing (results will be presented on this page soon).




Only the fiber goes through the MRI wall (no danger of coupling interference into the MRI room)