The staining was performed as previously described [19 (link)]. Briefly, brain sections were deparaffinized and hydrated with the clearing agent xylene and a series of grade ethanol. After washed 3 times with PBS, the brain sections were incubated in filtered 1% Thioflavin S (Sigma-Aldrich, St. Louis, MO) for 8 minutes at room temperature. The tissues were washed twice in 70% ethanol, washed in PBS and mounted under a coverslip with anti-fading mounting media. The images were captured using the Nikon TiE fluorescent microscope (Nikon Instruments Inc., Melville, NY).