Neuromagnetic oscillatory brain responses
First, we compared the oscillatory ssVEF responses in cortical source space between the two pre-cue conditions, in which subjects had to attend the central fixation cross or two peripheral flickering rings. Thereby, the dipoles on the canonical cortex surface that captured significant oscillatory ssVEF power different from background noise were determined by the F-ratio test (see Methods) for each pre-cue condition, separately. Figure 2 shows the power spectra and ssVEF topographies for both pre-cue conditions, and the spatial distribution of significantly oscillating cortical sources for the “attend to fixation cross” and “attend to both rings” conditions, respectively. Only cortical sources that exceeded the critical threshold of the F-ratio test are shown (critical minimum F ratio: F(2, 62) = 9.03, pfdr corrected < 0.001 for the central fixation condition; F ratio: F(2, 62) = 10.12, pfdr corrected < 0.001 for the peripheral rings condition). Both pre-cue conditions resulted in ssVEF responses in V1, and V2 in both hemispheres, whereas attending to the peripheral flickers activated more extended ssVEF power modulations in right occipito-parietal, and hMT+ areas including a small part of the right pre-cuneus.