Fig. 3.

MRS data of the DLPFC voxel. (A) Depiction of DLPFC MRS voxel positioning of a randomly selected participant and time point. The MRS voxel is overlaid on the participant- and time point-specific T1 structural scan. A glycerin maker was placed at the site of stimulation and was used to optimize MRS voxel positioning (marker visible on the coronal view). See Supplemental Fig. S3 for heatmaps representing the spatial overlap of voxel placement. (B) Spectra of all DLPFC MRS measurements (N = 150), from all participants and time points. GABA+ peak is visible at 3 ppm. Pre-TBS and post-TBS/task time points are depicted in green and magenta, respectively (mean spectrum across all participants and time points depicted in black). (C) ΔGABA in the four experimental conditions. Note that a pre- to post-intervention GABA+ increase and decrease are represented by values above and below 1 (indicated by the black dashed line), respectively. Exploratory analyses indicate that ΔGABA significantly differed between the iSEQ and iRND conditions. See Supplemental Table S8 for quality metrics and tissue segmentation, Supplemental Table S9 for follow-up tests for significant effects on tissue fractions and Supplemental Table S10 for raw GABA+ values. Error bars indicate SEM. Circles represent individual data points. Asterisk represents significant paired t-test with p < .05 (uncorrected for multiple comparisons). TBS: theta-burst stimulation, i: intermittent, c: continuous, SEQ: sequence, RND: random.