title: Neurobiological effects of transcranial direct current stimulation: a review.
abstract: Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique that is affordable and easy to operate compared to other neuromodulation techniques. Anodal stimulation increases cortical excitability, while the cathodal stimulation decreases it. Although tDCS is a promising treatment approach for chronic pain as well as for neuropsychiatric diseases and other neurological disorders, several complex neurobiological mechanisms that are not well understood are involved in its effect. The purpose of this systematic review is to summarize the current knowledge regarding the neurobiological mechanisms involved in the effects of tDCS. The initial search resulted in 171 articles. After applying inclusion and exclusion criteria, we screened 32 full-text articles to extract findings about the neurobiology of tDCS effects including investigation of cortical excitability parameters. Overall, these findings show that tDCS involves a cascade of events at the cellular and molecular levels. Moreover, tDCS is associated with glutamatergic, GABAergic, dopaminergic, serotonergic, and cholinergic activity modulation. Though these studies provide important advancements toward the understanding of mechanisms underlying tDCS effects, further studies are needed to integrate these mechanisms as to optimize clinical development of tDCS.
authors.affiliation: Post-Graduate Program in Biological Sciences, Department of Physiology, Universidade Federal do Rio Grande do Sul Porto Alegre, Brazil ; Pharmacology Department, Institute of Basic Health Science, Universidade Federal do Rio Grande do Sul Porto Alegre, Brazil ; Laboratory of Pain and Neuromodulation, Hospital de Clínicas de Porto Alegre Porto Alegre, Brazil.
authors.forename: Liciane Fernandes
authors.initials: LF
authors.lastname: Medeiros
authors.forename: Izabel Cristina Custodio
authors.initials: IC
authors.lastname: de Souza
authors.forename: Liliane Pinto
authors.initials: LP
authors.lastname: Vidor
authors.forename: Andressa
authors.initials: A
authors.lastname: de Souza
authors.forename: Alícia
authors.initials: A
authors.lastname: Deitos
authors.forename: Magdalena Sarah
authors.initials: MS
authors.lastname: Volz
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.forename: Wolnei
authors.initials: W
authors.lastname: Caumo
authors.forename: Iraci L S
authors.initials: IL
authors.lastname: Torres
keywords: functional effects; long-term depression; long-term potentiation; neurobiology; neuromodulation; tDCS