In recent years, the possibility of inducing cortical
excitability modulations in humans non-invasively by the
transcranial application of weak direct currents (tDCS) was
systematically evaluated by using transcranial magnetic
stimulation (TMS) for evaluation. Present data demonstrate
that tDCS of the primary motor cortex increases or
decreases cortical excitability for up to an hour after the
end of stimulation. The direction and duration of these shifts
in excitability depend on the polarity, intensity and duration
of the applied stimulation