In imaging functional connectivity (FC) analyses of the resting brain, alterations of FC during unconsciousness have been reported. These results are in accordance to recent electroencephalographic studies observing impaired top-down processing during anesthesia. In this study, simultaneous records of functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) were performed to investigate the causality of neural mechanisms during sevoflurane anesthesia by correlating FC in fMRI and directional connectivity (DC) in electroencephalogram.