Effect of transcranial direct current stimulation (tDCS) on MMN-indexed auditory discrimination: a pilot study
OBJECTIVE To evaluate the influence of frontal transcranial direct current stimulation (tDCS) on auditory mismatch negativity (MMN). METHODS MMN is an event related potential calculated by subtracting the amplitude of the evoked potentials in response to a "standard" stimulus from the evoked potentials produced by a rare "oddball" stimulus. Here we assessed the influence of anodal tDCS, cathodal tDCS or sham stimulation delivered over the right inferior frontal cortex on MMN in response to duration and frequency auditory deviants in 10 healthy subjects. RESULTS MMN to frequency deviants was significantly reduced after anodal tDCS compared with sham or cathodal stimulation which did not change MMN to frequency deviants. Neither anodal nor cathodal tDCS had any effect on MMN to duration deviants. CONCLUSIONS Non-invasive brain stimulation with tDCS can influence MMN. The differing networks known to be activated by duration and frequency deviants could account for the differential effect of tDCS on duration and frequency MMN. SIGNIFICANCE Non-invasive brain stimulation could be a useful method to manipulate MMN for experimental purposes.