Mechanisms and Effects of Transcranial Direct Current Stimulation
James Giordano,
Marom Bikson,
Emily S. Kappenman,
Vincent P. Clark,
H. Branch Coslett,
Michael R. Hamblin,
Roy Hamilton,
Ryan Jankord,
Walter J. Kozumbo,
R. Andrew McKinley,
Michael A. Nitsche,
J. Patrick Reilly,
Jessica Richardson,
Rachel Wurzman,
Edward Calabrese
Affiliations
James Giordano
Department of Neurology and Biochemistry, Neuroethics Studies Program, Pellegrino Center for Clinical Bioethics, Georgetown University Medical Center, Washington, DC, USA
Marom Bikson
Biomedical Engineering, City College of New York, CUNY, New York, NY, USA
Emily S. Kappenman
San Diego State University, Department of Psychology, San Diego, CA, USA
Vincent P. Clark
Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, USA
H. Branch Coslett
Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
Michael R. Hamblin
Wellman Center for Photomedicine, Massachusetts General Hospital and Department of Dermatology, Harvard Medical School, Boston, MA, USA
Roy Hamilton
Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
Ryan Jankord
United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
Walter J. Kozumbo
Hormesis Project, University of Massachusetts, Amherst, MA, USA
R. Andrew McKinley
United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
Michael A. Nitsche
Department Psychology and Neurosciences, Leibniz Research Center for Working Environmental and Human Factors, Dortmund, Germany
J. Patrick Reilly
Metatec Associates, Silver Spring, MD, USA
Jessica Richardson
Department of Speech and Hearing Sciences, University of New Mexico, Albuquerque, NM, USA
Rachel Wurzman
Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
Edward Calabrese
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.
