bands, no change in the β and low-γ bands, and increased synchronization within the left premotor, motor and sensorimotor regions in the high-γ range. There was also significant interhemispheric desynchronization in the α, β and high-γ bands (Figure 12). Another study combining left motor tDCS with fMRI resting state activity analysis (Polanía et al., 2011) showed increased connectivity within the left posterior cingulate cortex and the right dorsolateral prefrontal cortex, and an increase in mean path length within the left sensorimotor cortex. Intriguingly, seeded functional connectivity analysis of the left sensorimotor cortex revealed increased functional connectivity with left motor and premotor cortex, and with part of the superior parietal cortex, and no regions of decreased functional connectivity, suggesting that the increase in path length may be due to a strengthening of the motor network at the relative (but not absolute) expense of connections with other parts of the cortex. Functional connectivity analysis of the right dorsolateral prefrontal cortex showed increased connectivity with the right anterior insula, while that of the posterior cingulate demonstrated activation within regions corresponding to the default-mode network. Thus, these studies together demonstrate that tDCS produces widespread changes in the topology of brain functional connectivity, and that
