TY - JOUR A1 - Goldhacker, Markus A1 - Fellner, Marie-Christin A1 - Volberg, G. A1 - Mullinger, K. J. A1 - Greenlee, Mark W. A1 - Hanslmayr, Simon T1 - Spurious correlations in simultaneous EEG-fMRI driven by in-scanner movement JF - NeuroImage N2 - Simultaneous EEG-fMRI provides an increasingly attractive research tool to investigate cognitive processes with high temporal and spatial resolution. However, artifacts in EEG data introduced by the MR scanner still remain a major obstacle. This study, employing commonly used artifact correction steps, shows that head motion, one overlooked major source of artifacts in EEG-fMRI data, can cause plausible EEG effects and EEG–BOLD correlations. Specifically, low-frequency EEG (< 20 Hz) is strongly correlated with in-scanner movement. Accordingly, minor head motion (< 0.2 mm) induces spurious effects in a twofold manner: Small differences in task-correlated motion elicit spurious low-frequency effects, and, as motion concurrently influences fMRI data, EEG–BOLD correlations closely match motion-fMRI correlations. We demonstrate these effects in a memory encoding experiment showing that obtained theta power (~ 3–7 Hz) effects and channel-level theta–BOLD correlations reflect motion in the scanner. These findings highlight an important caveat that needs to be addressed by future EEG-fMRI studies. Y1 - 2016 U6 - https://doi.org/10.1016/j.neuroimage.2016.03.031 VL - 133 IS - June SP - 354 EP - 366 PB - Elsevier ER -