P197 Electroencephalographic effects of transcranial random noise stimulation of the temporal cortex

Abstract

Question Transcranial random noise stimulation (tRNS) is an innovative technique of non-invasive electrical stimulation with a handful of publications most of them investigating processes of the motor system. With respect to the auditory system only. Limited evidence is available for modulation of auditory processing in healthy controls and patients with chronic tinnitus. Here, we aimed to investigate the effects of tRNS over the auditory cortex on resting state and evoked activity in healthy subjects. Methods We used EEG to measure tRNS induced changes in resting state activity and in auditory steady state responses (ASSRs). Stimuli were 1000 Hz carrier frequency tones, amplitude modulated at 20 Hz and 40 Hz and applied in randomized order. Nineteen healthy subjects participated in a placebo-controlled randomized design study. Each subject received 20 min of high-frequency, low-frequency, and sham tRNS applied over auditory cortices with 2 mA, with a one week interval between the stimulation sessions. Results Data analysis is done at the moment of abstract submission. Thus, we hypothesize that we will be able to replicate previous findings that high-frequency tRNS will modulate the 40 Hz ASSR amplitude and the mean and variability of theta band power during resting state. Further analyses will aim at testing differences in the effects of high- and low-frequency tRNS. Conclusions Our findings of tRNS effects for processes of the auditory system will be discussed with respect to previous findings of tRNS effects on motor cortex excitability and to current concepts of tRNS mechanisms such as increase of stochastic resonance.