Fig. 1.

Overview of the available studies in WM. (A) Average weighted electric field on the neocortical surface across all unique stimulation montages. Warm colors indicate regions where on average electric fields were strong, whereas cold colors indicate regions where electric fields on average were weak. Stronger electric fields also indicate more commonly sampled areas across the studies. (B) Summary of the original experimental papers. The Left diagram depicts the proportion of stimulation frequencies (one frequency per condition), excluding 6.4% of outcome variables related to neither theta nor gamma frequencies. The Right diagram depicts explored WM modalities (visual, auditory, audio-visual) and domains [color, phonetic (word, letter), spatial, numeric, object]. (C) Summary of the tACS effects on WM for the primary target stimulation conditions and control stimulation conditions, including control frequencies and locations, across all studies and separately for theta and gamma stimulations (in Hedges’ g). See SI Appendix for the effect sizes of all 298 individual outcome measures.