Human brain tissue for this study was obtained from the Department of Pathology and Laboratory Medicine at UT Health Science Center at Houston. Blocks of tissue were dissected from the brains of three deceased individuals (14-year-old female, 75-year-old male, and 97-year-old female). To be consistent with the animal study, the somatosensory and visual cortex were chosen to perform the microglia and autofluorescence analysis. Formalin-fixed paraffin-embedded sections were immunostained with Iba1 antibody using tyramide signal amplification method (Biotium). Briefly, after deparaffinization, the sections were blocked in 0.3% hydrogen peroxide and blocking buffer (1% bovine serum albumin with 0.5% Triton X-100 in PBS), serially, and then the sections were incubated with anti-human Iba1 mouse monoclonal antibody (1:200; FUJIFILM, catalog no. NCNP27). The primary antibody was detected by horseradish peroxidase–conjugated goat anti-mouse secondary antibody (1:200) and colorized with CF488A tyramide dye in amplification buffer. Without autofluorescence elimination, the sections were coverslipped using Fluoroshield with DAPI mounting solution (Sigma-Aldrich). To obtain the representative images, the neocortex and subcortical white matter was scanned using a Leica THUNDER Imager DMi8 under 10× lens, and the high-magnification images (63× lens) were also taken from the same regions.