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Dose Response. 2017 Feb 9;15(1):1559325816685467. doi: 10.1177/1559325816685467. eCollection 2017 Jan-Mar.

Mechanisms and Effects of Transcranial Direct Current Stimulation.

Author information

Department of Neurology and Biochemistry, Neuroethics Studies Program, Pellegrino Center for Clinical Bioethics, Georgetown University Medical Center, Washington, DC, USA.
Biomedical Engineering, City College of New York, CUNY, New York, NY, USA.
San Diego State University, Department of Psychology, San Diego, CA, USA.
Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, USA.
Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Wellman Center for Photomedicine, Massachusetts General Hospital and Department of Dermatology, Harvard Medical School, Boston, MA, USA.
United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA.
Hormesis Project, University of Massachusetts, Amherst, MA, USA.
Department Psychology and Neurosciences, Leibniz Research Center for Working Environmental and Human Factors, Dortmund, Germany.
Metatec Associates, Silver Spring, MD, USA.
Department of Speech and Hearing Sciences, University of New Mexico, Albuquerque, NM, USA.
Environmental Health Sciences, University of Massachusetts, Amherst, MA, USA.


The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical populations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising applications include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose-response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged.


biphasic; dose–response; electrical stimulation; hormesis; hormetic; tDCS

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: CUNY has patents on brain stimulation with Bikson as an inventor. Bikson has equity in Soterix Medical Inc. Nitsche is on the advisory board of neuroelectrics—producing DC stimulators.

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