The choice of stimulation intensities for the temporal-alone and frontal-alone montages (Fig. 5a, b) was guided by current-flow modeling, which estimated that these stimulation intensities would reach their respective cortical targets with electric field strength similar as those produced by the frontotemporal montage (Fig. 1a). However, it is possible that the stimulation intensities used in Experiment 2 were not strong enough to effectively modulate these regions, individually, and that higher intensities (e.g., > 1.0 mA) are required to induce significant behavioral changes. To address this question, we invited back all subjects from Experiment 2 to participate in an additional two test days, in which the frontal-alone and temporal-alone montages were applied with the same stimulation intensity as the frontotemporal montage (i.e., 1.6 mA). Consistent with results from Experiment 2 (Fig. 6), we observed no significant RT or accuracy differences between sham and the frontal-alone or temporal-alone theta-tuned montages (ts27 < 0.813, ps > 0.423, dsz < 0.154).
