Functional connectivity modulation induced by transcranial direct current stimulation of the motor network: a Resting-State fMRI study

Resting-state functional connectivity represents a novel fMRI approach that allows detection of temporal correlations in spontaneous BOLD signal oscillations while subjects rest quietly in the scanner. Functional connectivity (FC) can be defined as the synchrony of neural activity among spatially distant regions. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is known to modulate cortical activity and FC among brain regions. This study is aimed at measuring the variation of functional connectivity between cortical brain regions after tDCS along time. The temporal concatenation group ICA showed that immediately after anodal stimulation the average value of voxels decreases significantly whereas there is no significant decrease in the case of sham tDCS stimulation. Our results show that anodal tDCS is able to induce connectivity changes within motor network, that is, reversible in a period lasting between 10′10′ and 20′20′ after stimulation.