A Review of Transcranial Direct Current Stimulation for Attention Modulation in Healthy Subjects

Attention is one of the highest cognitive functions among multitude processes including perception, memory, understanding, and learning. The first efforts for enhancement of attention are pharmacological methods whose side-effects sometimes dominate the beneficial effects. Then, the need for a noninvasive, low-cost, and efficient neuromodulation technique for improving attention method is necessary like transcranial direct current stimulation (tDCS). In this technique, a weak direct electrical current through anode or cathode electrodes, depolarizes or hyperpolarizes the cortical neurons and alters the excitability of them. This paper reviews the basic principles of tDCS, its procedures, and efficient protocols for improving attention in healthy subjects to the three network of attention: alerting, orienting, and executive control. Furthermore, the safety considerations of this technique as well as future clinical applications are discussed.