The long-lasting effect caused by direct current for somatosensory evoked potentials and high frequency oscillations

The long-term effects for the neural activities on somatosensory area caused by transcranial direct current stimulation (tDCS) have been showed with somatosensory evoked potentials (SEPs) and high frequency oscillations (HFOs) in animals and humans. This study investigates the relationship of SEPs with HFOs before and after applying cathodal tDCS (0, 15, 30, 45, 60 min) to human left somatosensory cortex for 15 min at 2 mA. The amplitudes of N20 and P30 evoked by right median nerve stimulation were slightly decreased after cathodal tDCS. Likewise, HFOs were affected by cathodal tDCS but there weren't steadily decrement during the entire HFO, the effects were oscillating depending on the peak of HFOs or the elapse time after tDCS. tDCS may leave the different influences between time- and location-dependent somatosensory processing.