Multimodal analysis of resting state cortical activity: what does fMRI add to our knowledge of microstates in resting state EEG activity? Commentary to the papers by Britz et al. and Musso et al. in the current issue of NeuroImage.

摘要

The functional state of living systems changes in a wide range of time scales: There are developmental changes from birth to death, daily wake-sleep cycles, fluctuations of attention in the range of seconds, and split-second states compatible with the speed of thoughts. EEG wave-shape oriented analysis captures spontaneous changes down to the second range (Berger, 1929) where resting (no task, no stimulus) state EEG has well-known norms, and systematic deviations from those norms are observed in specific macrostates of perception, cognition, attention, development, vigilance, drug conditions, and pathology (e.g., John et al., 1988; Niedermeyer and Lopes da Silva, 2005). The claims about the function of resting states and their disturbances in the more recent fMRI literature parallel these known EEG findings. However, the type of description of the resting states obtained from EEG and fMRI are very different (see, e.g., Laufs et al., 2006). Space-oriented EEG analysis yields state descriptions with millisecond time resolution. This approach was utilized in the two independent papers by Britz et al., 2010; Musso et al., 2010 in the current issue of Neurolmage. In fMRI-EEG coregistrations and coanalyses, the two papers demonstrate that fMRI resting states reflect certain aspects of EEG microstates in the split-second range.