Impact of Global Mean Normalization on Regional Glucose Metabolism in the Human Brain

Figure 6

Spatial distributions of metabolic variations in the congenitally blind (i.e., CB in Figure 2(a)) versus the eyes closed control group (i.e., HAEC in Figure 2(a)), shown with respect to unthresholded Student’s -maps using (a) qCMR_glc images and (b) GMN images. (a) For the CB group, the unthresholded -maps with qCMR_glc images indicated both regions with increased and decreased metabolism in association with blindness. Unidirectional metabolic decreases were observed in CB in most regions other than visual areas. (b) Similarly, the unthresholded -maps with GMN indicated regionally bidirectional metabolic changes with blindness and unidirectional metabolic increases were observed in regions associated with vision. Based on validation of qCMR_glc to aCMR_glc-HYD (Figures 1 and 2; Table 2), with and without GMN the global changes were essentially negligible. There were increases/decreases in visual/nonvisual areas, either with or without GMN. See Figure S6 for thresholded maps (Table 4).