the number of cycles included in the mother wavelet set to 6 to increase frequency resolution. Long-range theta-band synchronization was assessed from 4–8 Hz in 0.1-Hz increments and computed using PLV 62 in source space between left temporal cortex and left prefrontal cortex during memory maintenance (500 to 3000 ms post-target onset) on memory versus control blocks. Within the theta band, the frequency with maximum mean PLV was extracted on an individual subject basis and served as the target stimulation frequency. Individually frequency-tuned stimulation was applied with 0.5-Hz resolution, rounding up from 0.3 Hz. For example, an individual with a peak synchronization frequency of 7.2 Hz was given 7-Hz stimulation, whereas an individual with a peak at 7.3 Hz was given 7.5-Hz stimulation.
