SIMULTANEOUS FUNCTIONAL MAGNETIC-RESONANCE-IMAGING AND ELECTROPHYSIOLOGICAL RECORDING

The purpose of this study was to develop a method for obtaining simult aneous electrophysiological and functional magnetic resonance imaging data. Using phantom experiments and tests on several of the investigat ors, a method for obtaining simultaneous electrophysiological and fMRI data was developed and then tested in three volunteers including two task activation experiments. It was then applied in a sleep experiment (n = 12). Current limiting resistance and low-pass filtering were add ed to the electrophysiological circuit. Potential high frequency curre nt loops were avoided in the electrical layout near the subject. MRI w as performed at 1.5 T using conventional and echo planar imaging seque nces. There was no evidence of subject injury. Expected correlations w ere observed between the electrophysiological and fMRI data in the tas k activation experiments. The fMRI data were not significantly degrade d by the electrophysiological apparatus. Alpha waves were detected fro m within the magnet in seven of the 15 experimental sessions. There wa s degradation of the electrophysiological data due to ballistocardiogr aphic artifacts (pulsatile whole body motion time-locked to cardiac ac tivity) which varied between subjects from being minimal to becoming l arge enough to make detection of alpha waves difficult. We concluded t hat simultaneous fMRI and electrophysiological recording is possible w ith minor modifications of standard electrophysiological equipment. Ou r initial results suggest this can be done safely and without compromi se of the fMRI data. The usefulness of this technique for studies of s uch things as sleep and epilepsy is promising. Applications requiring higher precision electrophysiological data, such as evoked response me asurements, may require modifications based on ballistocardiographic e ffects. (C) 1995 Wiley-Liss, Inc.