Figure 4. Thirty transverse MR image sections on a random effects group analysis map generated for nine subjects who performed the N-back working-memory task. Brain activation increased with increasing task difficulty, as indicated by the red, orange, and yellow areas. Brain activation also increased with decreasing task difficulty, as indicated by the blue areas. Background images are a template derived from the mean of 20 normalized inversion-recovery-prepared gradient-echo MR images (8/3.4/600, 15° flip angle) obtained in a group of healthy elderly men. Images are shown in neurologic convention (ie, image left corresponds to subject left).