Fig. 1

NIBS methods. a TMS. b tDCS. a TMS is able to generate a brief electric field in the targeted brain surface that causes a rapid depolarization of neurons above threshold. The repeated application of TMS (rTMS) induces effects that are defined as neuromodulation: low-frequency rTMS (< 1 Hz) mainly induces a reduction in the excitability, while high-frequency rTMS (between 5 and 25 Hz) induces facilitating effects in terms of excitability of the stimulated area (see [24]). b tDCS involves the application of weak electrical currents directly to the scalp, through a pair of electrodes, for a few minutes (~ 5–20). These currents generate an electric field that modulates neuronal activity. Several studies showed that anodal tDCS increases the frequency of neurons spontaneous discharge in the stimulated area, while cathodal tDCS has the opposite effect (see [25, 26])