Impact of Global Normalization in fMRI Acupuncture Studies
Figure 2
Correlations between the global signal (GS), reference vector (RV), and voxel-level time series. (a) and (b) indicate the correlation between the GS-RV -value and AVER-WB-RV -value (NO PSGS) for the acupuncture and tactile runs, respectively. Dots in each panel represent the subjects. The larger dots in orange and blue indicate the significant values of positive and negative correlations, respectively (, corrected). (c) and (d) manifest the linear relationship between the GS-RV -value and changes in the AVER-WB-RV -value (PSGS-NO PSGS) for the acupuncture and tactile runs, respectively. Dots also represent the subjects. (e) shows the mean and standard deviation (SD) of the AVER-WB-RV -value across subjects for NO PSGS with a dark grey bar and for PSGS with a light grey bar in the acupuncture and tactile runs, respectively. (f) shows the mean and SD of the number of activations and deactivations across subjects for NO PSGS and PSGS. The numbers of activations for NO PSGS and PSGS are shown in black and dark grey bars, respectively. The numbers of deactivations for NO PSGS and PSGS are shown in white and light grey bars, respectively. Each number is calculated at , uncorrected.
