Safety, Tolerability, Blinding Efficacy and Behavioural Effects of a Novel MRI Compatible, High Definition tDCS Set Up
BACKGROUND High definition transcranial direct current stimulation (HD tDCS) may allow more specific neural modulation than conventional tDCS. OBJECTIVE We compared safety, tolerability, blinding efficacy and cognitive effects of a novel HD tDCS set up to that of conventional tDCS and established compatibility with simultaneous functional magnetic resonance imaging (fMRI) METHODS Two groups of healthy participants completed a visual flanker task either with conventional (N 30) or HD tDCS (N 30) administered to the right dorsolateral prefrontal cortex (1 mA) in a double blind, sham tDCS controlled, cross over design. HD tDCS was administered with a one channel DC stimulator using a small conductive rubber "centre" electrode and a circular return electrode, mimicking the frequently used 4 x 1 HD tDCS set up. Tolerability, adverse effects, impact on performance and blinding efficacy were compared within and between the two montages. In a separate experiment, potential heating and impact on image quality of the novel HD tDCS set up were assessed during simultaneous fMRI. RESULTS Both montages elicited only mild adverse effects and those were less pronounced for the novel HD tDCS set up. Participant and investigator blinding was achieved with both montages. Only HD tDCS resulted in significant modulation of the conflict adaptation effect during the flanker task; however, no differences were found for the direct comparison of the two montages. No significant heating occurred during fMRI and only minor effects on image quality were observed during HD tDCS. CONCLUSIONS This study confirmed safety, tolerability and blinding efficacy of a novel, re usable and MRI compatible HD tDCS set up. It also highlights its potential to exert beneficial effects on behavioural performance. Use of this novel set up during simultaneous fMRI in future studies will help clarify the neural mechanisms by which this HD tDCS impacts on behavioural and neural function.
Brain Stimulation