Quantifying and visualizing the transcranial direct current stimulation research indicators

The field of transcranial direct current stimulation (tDCS) has experienced significant growth in the past 15 years which is mainly devoted to determining the basic and clinical potential of tDCS in humans. The aim of this study is to quantitatively analyze the current worldwide progress on tDCS research as well as to highlight researchers, journals, institutions and countries which are contributing significantly in the past 18 years. We conducted a quantitative analysis of research articles regarding tDCS published from 1998 to 2016 and indexed in the web of science core collection database. Data was downloaded in October, 2016. In the past 18 years, there were 2457 studies on tDCS indexed by web of science database, including all documents type such as article, review, meeting abstract, proceedings paper, letters, and etc. This study is focusing on the main articles and reviews; therefore, the research production was reduced to 2000 publications. The analysis showed that most of the studies in the field were published by North American and European institutions with a reasonable proportion of the publications were also by Japanese institutions from Asia. From the perspective of research progress, we found that the number of published papers on tDCS has increased significantly in the past 10 years, between them a remarkable positive correlation exists.