Figure 4
Causal impact of right FEF stimulation on evoked high-beta oscillations. Evoked oscillations (25–35 Hz, [−199.5 66.5] ms, [−2 2] µV) for rhythmic (A) and random (B) active/sham stimulation patterns for each of the 60 EEG scalp electrodes (left column; the location of electrode FC2, i.e., the closest to the stimulated right FEF, is indicated with an open circle) and at FC2 (right column). Vertical black dotted lines delineate the epochs employed for the analyses (T1: Pre TMS, T2: TMS burst part 1; T3: TMS burst part 2 and T4: Visual Target). Blue and red colors respectively represent the sham and active TMS conditions. Notice progressive increases in the amplitude of high-beta evoked oscillations (25–35 Hz), reaching higher levels during rhythmic than random active patterns throughout the course of 4-pulse stimulation patterns followed by a rather abrupt decay after the last pulse of the burst. (C) Amplitude (mean and standard error) of evoked oscillations (25–35 Hz) for rhythmic and random active/sham stimulation patterns across the 4 time-windows of interest (T1: Pre TMS; T2: TMS burst part 1; T3: TMS burst part 2; and T4: Visual Target). Due to the complexity of representation of interaction effects, significant statistical results are not shown in the figure. Notice, however, that active rhythmic patterns caused higher amplitude increases of evoked oscillations than active random patterns (significant stimulation pattern x stimulation condition interaction). In addition, we found a progressive build-up of evoked oscillations along the course of the 4-pulse burst (amplitude T1 < T2 < T3), and a decay following the offset of the stimulation (T4 < T3, significant stimulation condition x time window interaction).
