Fig. 2.

MEG results for the effect of spatial orienting of attention. (A) Topographies for the amplitude difference in the ERF 200–400 ms after target presentation in the left vs. right visual field (averaged over both short and long interval lengths). The six left and six right occipital-parietal channels that were used as ROIs throughout the subsequent MEG analysis are marked in black. Channels were selected based on visual inspection of the ERF grand average for all participants. Separate topographies for older and younger adults show that the largest ERF amplitude is found in the same channels for both groups. (B) Time-frequency representation (TFR) plots for older adults, younger adults and the difference between both groups (older-minus-younger), for contralateral ROI channels minus ipsilateral ROI channels (to the direction of the cue), averaged over both cue-target interval lengths. Results are shown for the short interval (0–800 ms) only. The colour scale indicates a relative increase or decrease. Significant clusters are outlined in white. The shaded area indicates a time period that cannot be considered purely anticipatory, because target-evoked activity might bleed in. (C) Topographies for the left-minus-right cue contrast (averaged over both interval lengths), separately for older adults, younger adults and the difference between both groups (older-minus-younger). Topographies are averaged over frequencies between 8 and 24 Hz and for a time window between 300 and 650 ms. Black dots represent the contralateral and ipsilateral visual ROI channels.