The Uncertain Outcome of Prefrontal tDCS

Background: Transcranial direct current stimulation (tDCS) is increasingly used in research and clinical settings, and the dorsolateral prefrontal cortex (DLPFC) is often chosen as a target for stimulation. While numerous studies report modulation of cognitive abilities following DLPFC stimulation, the wide array of cognitive functions that can be modulated makes it difficult to predict its precise outcome. Objective: The present review aims at identifying and characterizing the various cognitive domains affected by tDCS over DLPFC. Methods: Articles using tDCS over DLPFC indexed in PubMed and published between January 2000 and January 2014 were included in the present review. Results: tDCS over DLPFC affects a wide array of cognitive functions, with sometimes apparent conflicting results. Conclusion: Prefrontal tDCS has the potential to modulate numerous cognitive functions simultaneously, but to properly interpret the results, a clear a priori hypothesis is necessary, careful technical consideration are mandatory, further insights into the neurobiological impact of tDCS are needed, and consideration should be given to the possibility that some behavioral effects may be partly explained by parallel modulation of related functions. (C) 2014 Elsevier Inc. All rights reserved.