Schematic drawing of FDG-PET imaging procedure. After subjects were acclimatized by looking at the stationary dot pattern outside the scanner, the visual motion stimulation (CV or random dot movement) started simultaneously with the application of intravenous 18-FDG and continued for 22 minutes. Afterwards the subjects were quickly transferred to the PET scanner, where they immediately closed their eyes. The PET scans were measured under standard resting conditions in the same quiet and darkened room with eyes closed. The emissions scan started 8 minutes after the end of visual motion stimulation (30 minutes after injection) and continued for 20 minutes (standardized procedure).