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.

Transcranial Direct Current Stimulation for Treatment of ADHD: A Review of the Mechanisms of Action

“…Consistent with the recent studies, through neuropsychiatric abnormalities, the implication of an effective tech-nique which can hopefully elucidate brain mechanisms; actuates the neuroscience to more investigation about noninvasive brain stimulation like tDCS to fortify the knowledge of cognitive and neurophysiological diseases [32].TDCS delivers a weak direct constant electrical current to the scalp through electrodes [33]. Consequently, neuronal membrane excitability changes in response to the electrical current.…”

Transcranial direct current stimulation enhances recovery from motor deficits following hypoxia-ischemia in neonatal rats

“…There is much debate about the underlying mechanisms behind the effects of tDCS [20]. There has been growing knowledge of how peripheral nerve stimulation can affect the CNS reportedly producing many similar effects to that of tDCS [21].…”

Impact of 3-Day Combined Anodal Transcranial Direct Current Stimulation-Visuospatial Training on Object-Location Memory in Healthy Older Adults and Patients with Mild Cognitive Impairment

“…Behavioral on-and offline effects may differ in underlying mechanisms and might thus be differently susceptible to atDCS [24]. Online performance (improvement during stimulation within a training day) seems to be mainly related to subthreshold alterations in membrane potential [101][102][103][104]. Similar to recent meta-analytic results, which summarized studies of working memory in HE and in patients with depression, idiopathic Parkinson's disease, or schizophrenia [105], we found a beneficial online effect in MCI, as opposed to HE, but only on the third training day.…”