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