Figure 6. Effects of stress on hippocampal and midbrain activity related to memory formation. Statistical parametric maps are superimposed onto spatially normalized single-subject high-resolution T1-weigted canonical images (thresholded at p < 0.001, uncorrected, for visualization purposes). A, Sagittal view of activation in the right hippocampus associated with the main effect of memory (SME) across the two groups. B, Averaged beta values in the right hippocampus representing trials later remembered and forgotten for both groups. C, Coronal (top) and sagittal (bottom) view of suprathreshold clusters in the midbrain for the interaction effect between memory and stress. D, Averaged beta values extracted from an anatomically defined midbrain mask representing trials later remembered and forgotten for both groups. E, F, Transversal view of representative slices for clusters covering the approximate location of midbrain nuclei that are known to be involved in regulation of arousal, homeostatic balance, and vegetative functions, and are also involved in modulation of learning and memory; E′, F′, Same slices as displayed in E and F, respectively, but with a less stringent yet acceptable cluster threshold of p < 0.05, corrected, after thresholding at p < 0.005, uncorrected, at the voxel level. Localization of these clusters should be interpreted cautiously given limited spatial resolution. Stress, Stress group; Control, control group; F, encoding trials later forgotten; R, encoding trials later remembered; SN, substantia nigra; LC, locus ceruleus; *p < 0.05; **p < 0.01.