Research paperResting-state fMRI reveals enhanced functional connectivity in spatial navigation networks after transcranial direct current stimulation

•tDCS modulates resting state functional connectivity in a polarity dependent manner.•tDCS primed extended networks that are refined according to task-demands.•Anodal tDCS may prove beneficial in patient populations with abnormal connectivity.

A number of studies have established that transcranial direct current stimulation (tDCS) modulates cortical excitability. We previously demonstrated polarity dependent changes in parietal lobe blood oxygen level dependent (BOLD) fMRI in a group of young adults during a spatial navigation task [15]. Here we used resting state functional connectivity (rsFC) to examine whether analogous changes were also evident during the resting state. Participants were randomized to either a parietal-anodal, frontal-cathodal (P+F−) or the opposite montage (P−F+) and received 20 min of tDCS (2 mA) before undergoing resting-state fMRI. rsFC was evaluated between the groups by placing a seed in the medial superior parietal lobule (mSPL), which was under the target electrode. rsFC between the mSPL and a number of other areas involved in spatial navigation, scene processing, and sensorimotor processing was significantly higher in the P+F− than the P−F+ group. Thus, the modulatory effects of tDCS were evident during rest and suggest that stimulation primes not just the underlying neocortex but an extended network that can be recruited as necessary during active task performance.