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What is tDCS?

What-is-tDCS

tDCS or Transcranial Direct Current Stimulation is a non-invasive form of brain stimulation. The technology involves the use of a  constant direct current, between 1-2 mA, delivered to targeted areas of the brain through the use of electrodes. tDCS can be used to either “excite” or “inhibit” neuronal activity. In anodal stimulation, current is sent into the brain, exciting nearby neurons and increasing neuronal activity whereas in cathodal stimulation, current is drawn out of the brain reducing neuronal activity.

Mechanism of Action:

tDCS works be causing a change in the targeted neuron’s resting membrane potential.  When anodal stimulation is applied, a depolarization of the resting membrane potential of the targeted neurons occurs. This “primer” in turn increases the neuron’s excitability and allows the affected neurons to more readily fire. Conversely, cathodal stimulation causes the targeted neuron’s to become hyperpolarized.  This change in resting membrane potential decreases neuronal activity and reduces cell firing.

Safety:

When used in accordance to the established safety protocols tDCS is considered a safe form of brain stimulation. Adverse effects appear to be limited to headaches and itchiness and redness near the electrodes (stimulation site).  By slowly ramping up to the desired current irritation and light headedness can be reduced or avoided. If an electrode is placed to close to the eye phosphene’s (brief flashes of light) may be seen.

Electrode Placement:

tDCS electrode placement is based of the established 10-20 EEG system for mapping the brain locations on the scalp.  The system is internationally recognized and may sometimes be referred to as the 10-10 system. The 10 and 20 refer to the distance , 10% or 20%,  of the distance between the total front-back or left-right distance of the skull.  Each site location has a letter and a number to indicate its respective location on the skull. This is done by assigning a lobe letter, F (Frontal), P (Parietal), T (Temporal), C (Central), or O (Occipital) in combination with a hemisphere number, even for right hemisphere and odd for left hemisphere.  Click here to view our Electrode Placement Map page for a detailed step by step guide and instructional videos.

Want To Learn More?

The below videos held at a summit on tDCS at UC-Davis Center for Mind and Brain will help provide a deep understanding about this exciting technology.

 

Published on Oct 8, 2013
Dr. Marom Bikson, Associate Professor of Biomedical Engineering at The City College of The City University of New York, discussing the cellular mechanisms of transcranial direct current stimulation (tDCS) at the Summit on Transcranial Direct Current Stimulation (tDCS) at the UC-Davis Center for Mind & Brain.

Published on Oct 8, 2013
Dr. Vince Clark, Professor of Psychology and Neuroscience at the University of New Mexico, speaking on the role of tDCS in cognitive enhancement in a talk at the Summit on Transcranial Direct Current Stimulation (tDCS) at the UC-Davis Center for Mind & Brain.

Published on Oct 8, 2013

Dr. Vincent Walsh of University College London, discussing the current evidence for and against the role of transcranial direct current stimulation (TDCS) in improving cognition at the Summit on Transcranial Direct Current Stimulation (tDCS) at the UC-Davis Center for Mind & Brain.

Published on Oct 8, 2013
In this talk at the Summit on Transcranial Direct Current Stimulation (tDCS) at the UC-Davis Center for Mind & Brain, Dr. Roy Hamilton, Assistant Professor of Neurology at the University of Pennsylvania, discusses a range of clinical applications of the transcranial direct current stimulation (tDCS) technique.

Published on Oct 8, 2013
Dr. Michael Nitsche, a pioneer in the field of transcranial direct current stimulation (tDCS) from the University of Goettingen in Germany, speaking about the physiological basis of tDCS at the Summit on Transcranial Direct Current Stimulation (tDCS) at the UC-Davis Center for Mind & Brain.

Published on Oct 8, 2013
Dr. Dylan Edwards of the Burke Medical Research Institute, speaking on the role of tDCS and robotics in human motor recovery in a talk at the Summit on Transcranial Direct Current Stimulation (tDCS) at the UC-Davis Center for Mind & Brain.