Fig. 5: Experimental setup.
a, Illustration of the SFTT15,22: participants were asked to reproduce a sequence displayed on a screen with a four-button box. b, Protocol of the task sessions in experiment 1: the baseline measurement was followed by training with concomitant stimulation, consisting of six blocks containing ten 30-s task repetitions alternated with 30-s rest periods. c, Protocol of experiment 2: the baseline measurement was followed by training with concomitant stimulation, consisting of seven repetitions of 1 min 30 s task blocks. A post assessment (Post) with three block repetitions was performed immediately after and in a follow-up assessment ~90 min (FU1) after and ~24 h (FU2) after the end of the stimulation. d, TI stimulation concept. On the left, two pairs of electrodes are shown on a head model, and currents are applied with frequencies of f1 and f1 + Δf. On the right, the interference between the two electric fields within the brain is plotted at two different locations with high and low envelope modulation. e, In the pulsed stimulation mode, the frequency shift is only introduced during an exposure phase, for example, a burst. This allows the delivery of patterned intermittent theta-burst protocols in which three pulses of amplitude modulation at 100 Hz (burst phase) are repeated every 200 ms (theta frequency) for a 2-s train. The trains are repeated every 10 s. f, Electric field modeling with the striatal montage. Top: the electric tTIS exposure distribution in three chosen slices passing through the target region. Bottom: a 3D reconstruction of the structural MRI data, highlighting the electrode positioning.