Cognitive Plasticity and Transcranial Electrical Stimulation

This chapter provides an introduction to transcranial electrical stimulation (tES), a non-invasive method for modulating activity in the underlying cortex by delivering a weak electrical current through electrodes placed on the scalp. Starting with an introduction to different types of stimulation, we go on to discuss our current understanding of the neurophysiological mechanisms of tES before reviewing its utility as a tool to enhance cognitive function during and after cognitive training. While there is some evidence that tES can be used in conjunction with cognitive training to improve both training gains and transfer to untrained cognitive tasks, the results are mixed and inconclusive with as many studies reporting null effects as those that report positive effects. We discuss possible reasons for these inconsistent results and conclude that to fully understand the potential benefits of tES for enhancing cognitive plasticity we must: (i) develop a better understanding of how the cellular mechanisms of tES contribute to changes at the level of the cortex and (ii) consider optimising tES protocols at the level of the individual.