Fig. 4
A Functional connectivity. Resultant cluster (PFDR < 0.05; Punc < 0.001 in yellow, punc < 0.005 in red) from seed-to-voxel resting-state FC analysis with seed in stimulation target (lMFG). Cluster location in the right supramarginal/angular gyrus (x = 44, y = − 40, z = 50) and in the right superior/middle frontal gyrus (x = 22, y = − 4, z = 60): increase in FC to the stimulation target in the anodal group compared to the sham group. Means (black diamonds for anodal and white diamonds for sham) and individual datapoints (single circles in orange/red for anodal and light blue/dark blue for sham). Box plots indicate median (middle line), 25th, 75th (box), and 5th and 95th percentile (whiskers). N = 27 independent participants. sbFC, seed-based functional connectivity. lMFG, left middle frontal gyrus. tDCS, transcranial direct current stimulation. RH, right hemisphere. B Computational modeling of electric fields. Group average of electric fields induced by anodal tDCS (in V/m), projected in “fsaverage” space. Scatterplots display the correlation between electric field magnitudes and change in N-back task performance (Post minus Pre of d-prime values), anodal: ρtDCS = 0.6, P = 0.02; sham: ρsham = − 0.24, P = 0.31. Note that sensitivity analysis for the anodal group without the outlier yielded similar Spearman’s correlation coefficient (ρtDCS = 0.5, P = 0.05)