Figure 2.

(a) and (b): The N400 repetition effects, ie, the difference waveforms (300–550 ms) generated by subtracting ERPs to incongruous old target words from ERPs to incongruous new target words, within each group. Robust treatment effects were demonstrated within the shaded right posterior cluster consisting of five electrodes (visit × treatment interaction: F_(1,39)=7.58, p=0.009, η²=0.163), with significant decreases (mean=1.1 μV) in the placebo group (p=0.033) and an insignificant trend for N400 repetition effect amplitude increases (mean=0.54 μV) in the memantine group (p=0.16). (c) and (d): Topographic distribution of the N400 repetition effects across the early (300–400 ms) and late (400–500 ms) time windows, plotted by treatment group and visits, within each group.