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Updated: Jun 23, 2026
Transcranial Electrical Brain Stimulation in Alert Rodents
Published on: November 2, 2017
Safety limits of cathodal transcranial direct current stimulation in rats
David Liebetanz1, Reinhard Koch, Susanne Mayenfels
1Department of Clinical Neurophysiology, University Medical Center Göttingen, Robert-Koch-Strasse 40, 37099 Göttingen, Germany. dliebet@gwdg.de
Objective:
The aim of this rat study was to investigate the safety limits of extended transcranial direct current stimulation (tDCS). tDCS may be of therapeutic value in several neuro-psychiatric disorders. For its clinical applicability, however, more stable effects are required, which may be induced by intensified stimulations.
Methods:
Fifty-eight rats received single cathodal stimulations at 1-1000 microA for up to 270 min through an epicranial electrode (3.5 mm(2)). Histological evaluation (H&E) was performed 48 h later. A threshold estimate was calculated from volumes of DC-induced lesions.
Results:
Brain lesions occurred at a current density of 142.9 A/m(2) for durations greater than 10 min. For current densities between 142.9 and 285.7 A/m(2), lesion size increased linearly with charge density; with a calculated zero lesion size intercept of 52,400 C/m(2). Brains stimulated below either this current density or charge density threshold, including stimulations over 5 consecutive days, were morphologically intact.
Conclusion:
The experimentally determined threshold estimate is two orders of magnitude higher than the charge density currently applied in humans (171-480 C/m(2)). In relation to transcranial DC stimulation in humans the rat epicranial electrode montage may provide for an additional safety margin.
Significance:
Although these results cannot be directly transferred to humans, they encourage the development intensified tDCS protocols. Further animal studies are required, before such protocols can be applied in humans.
