Application of Transcranial Electric Stimulation (tDCS, tACS, tRNS)

Abstract

Low-intensity transcranial electrical stimulation (tES) techniques are a group of noninvasive brain stimulation approaches, where currents are applied with intensities ranging between 0.4 and 2 mA through the human scalp. The most frequently used tES methods are transcranial direct current (tDCS), alternating current (tACS), and random noise stimulation (tRNS). These methods have been shown to induce changes in cortical excitability and activity during and after the stimulation in a reversible manner. It was observed that while anodal and cathodal tDCS acts on the membrane potentials by depolarizing or hyperpolarizing them, tACS probably modifies cortical oscillations. tRNS, that is a special form of tACS, might act through affecting the signal-to-noise ratio in the brain. Currently, an exponentially increasing number of studies have been published regarding the effects of tES on physiological processes and cognition. The aim of this review is to summarize the basic aspects of tES methods.