Figure 2.
Group-averaged MEG and EEG sensor-level signals. a, MEG areal mean signals calculated over the occipital (O), parietal (P), and left and right occipitotemporal (LOT, ROT), temporal (LT, RT), rolandic (LR, RR), and frontal (LF, RF) cortex, and averaged across 15 participants. The sensor-level areal mean MEG signals were calculated as vector sums; thus, they always have a positive value (>0). b, EEG areal mean signals during the MEG recording calculated across the occipital (O), parietal (P), and left and right temporal (LT, RT) and frontal (LF, RF) electrodes, and averaged across 13 participants. Negative values of the electric potential are plotted upwards. c, EEG areal mean signals during the fMRI recording. d, EEG difference waveforms. The curves show EEG during MEG minus EEG during fMRI, averaged across 13 participants. For each stimulus type, the difference waveforms for the 28 EEG electrodes are overlaid. A salient difference between the two EEG recordings at ∼500–800 ms is due to an eye-movement artifact in the two most frontal electrodes (FP1–2) that could not be fully removed from the EEG recorded during fMRI.