Delta wave MRI - fMRI imaging of electrophysiological activity

Abstract

We propose a novel application of MR encephalography (MREG) to detect the frequency spectrum of endogenous slow oscillatory brain activity (delta, <4 Hz)[1]. MREG offers faster image acquisition than conventional fMRI and superior spatial localization than EEG/MEG. MREG was acquired at 0.1 s temporal resolution in a healthy adult during interleaved wakefulness and sleep to demonstrate its capability for detecting delta-band power changes associated with sleep [2] previously demonstrated by electroencephalography (EEG). For each voxel, the brain activity MREG signal was used to compute a spectrogram and whole brain image of delta-band spectral power. Delta-band power was observed to increase during sleep as compared to awake states using measures from MREG voxel-wise spectrograms and sequential whole brain spatial maps of slow wave power. This work introduced an MR technique for measuring brain slow wave activity which is sensitive to changes in the magnitude and frequency of brain activity in sleep.ABBREVIATIONS: MREG: Magnetic resonance encephalography BOLD: Blood oxygen level dependent.