PMC4182437_01
Stability of wakefulness under MV and SB indexed by EEG.. (A). Scalp voltage topographies of alpha power (up) and theta (bottom) averaged across the 4 EEG-fMRI sessions reveal a typical pattern of wakefulness characterized by a high posterior alpha power and a low anterior mid-frontal power. (B). Dynamics of the (posterior alpha power)/(mid-frontal theta power) ration is plotted across time for the 4 EEG-fMRI sessions. This index of wakefulness was stable across the 4 sessions, and confirmed a stable level of wakefulness all along the fMRI experiments, with no difference between SB and MV.
pone.0107850.g001.jpg
PMC4182437_01_pone.0107850.g001.jpg
pone-0107850-g001
Then, for each time sample, we computed the ratio between relative alpha power averaged over occipital electrodes, and theta power averaged over frontal electrodes (see Figure 1A).