Using high-amplitude and focused transcranial alternating current stimulation to entrain physiological tremor.

ABSTRACT: Transcranial alternating current stimulation (tACS) is a noninvasive neuromodulation method that can entrain physiological tremor in healthy volunteers. We conducted two experiments to investigate the effectiveness of high-amplitude and focused tACS montages at entraining physiological tremor. Experiment 1 used saline-soaked sponge electrodes with an extra-cephalic return electrode and compared the effects of a motor (MC) and prefrontal cortex (PFC) electrode location. Average peak-amplitude was 1.925?mA. Experiment 2 used gel-filled cup-electrodes in a 4?×?1 focused montage and compared the effects of MC and occipital cortex (OC) tACS. Average peak-amplitude was 4.45?mA. Experiment 1 showed that unfocused MC and PFC tACS both produced phosphenes and significant phase entrainment. Experiment 2 showed that focused MC and OC tACS produced no phosphenes but only focused MC tACS caused significant phase entrainment. At the group level, tACS did not have a significant effect on tremor amplitude. However, with focused tACS there was a significant correlation between phase entrainment and tremor amplitude modulation: subjects with higher phase entrainment showed more tremor amplitude modulation. We conclude that: (1) focused montages allow for high-amplitude tACS without phosphenes and (2) high amplitude focused tACS can entrain physiological tremor.

SUBMITTER: Khatoun A 

PROVIDER: S-EPMC5862845 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature