Figure 7. Quantification of Mn²⁺-induced intensity changes over time after injection in the contralateral hippocampus and septal nuclei of old WT and old APPSwInd.

(A-B) Shown are anatomical segmentations of the right hippocampus, (A, green), the left hippocampus (A, yellow) and the septal nuclei (B, yellow) projected onto a semi-transparent grayscale rendering of our 3D mouse brain template. Red boxes in (B) indicate the locations of the 5 × 5 × 5 voxel cubes (0.5 mm³) selected for region of interest (ROI) intensity measurements in the MSN and LSr. (C) shows a 3D rendering of the mouse template in the axial orientation. The red box indicates the position of the 0.5 mm³ ROI used for measurements in the cortex which had stable intensity over time as it is not an expected destination in this circuit, and thus useful for background correction. Locations of ROIs were chosen based on SPM maps and propagated through all aligned images such that the same anatomical region was measured across all animals and time points. Measurements are made at successive time points after injection (0.5, 6 and 24h).

(D-F) Graphs showing changes in mean intensity over time after Mn²⁺ injection for indicated regions at each imaging time point for each cohort, with old WT (blue lines) and old APPSwInd (red lines). Error bars represent standard error of the mean. All measurements were back-ground corrected and normalized. Statistics represent a two-way ANOVA with repeated measures for time (group × time; F_(4,50) = 2.658, p≤0.04), with Tukey’s post-hoc test (* p≤0.5; ** p≤0.01). (D) Intensity changes in the segmented contralateral hippocampus. (E) Mean intensity changes in the ROI in the medial septal region (MSN, red box in B).

(F) Mean intensities in the lateral septal region (LSr, red box in B).