Abstract: Simultaneous EEG-fMRI integrates the complementary advantages of high-temporal-resolution EEG and high-spatial-resolution fMRI. As the traditional electrophysiological method was employed to sleep staging and event potential recording, simultaneous EEG-fMRI provides a non-invasive multimodal measurement of sleep and may clarify the cognition process in different consciousness condition. This review provides the recent development in spontaneous activity and sensory processing during sleep. We discussed some specific topics in sleep investigation, such as hardware, subjective and data process problems. The application of simultaneous EEG-fMRI has profound significance for elucidating the neural mechanism of conscious state conversion, and will provide new ideas for the diagnosis and treatment of the sleep disorders.

Key words: multimodal, simultaneous EEG-fMRI, rapid-eye-movement sleep, non rapid-eye-movement sleep