Properties of the AIS are unchanged in the vicinity of a plaque. A, Cortex of 18-month WT and R1.40 mouse immunolabeled for βIV-spectrin (green), APP (6E10 antibody, red), and MAP2 (blue). Scale bar, 10 µm. B, Three concentric rings (50, 100, and 150 μm in diameter) were centered on an Aβ (6E10⁺) plaque and used to define three ROIs (A–C). AISs were immunostained using antibodies against βIV spectrin (green). Scale bar, 20 µm. C, Quantification of the length of the AIS in the three regions. D, Quantification of the density of AIS in the three regions. The differences shown in C and D were not significant by one-way ANOVA. n = 3. Data are mean ± SEM.