Embryonic rat hippocampal neurons were prepared as previously described (see Kaech and Banker, 2006, Nat Protoc). Cells were prepared for fluorescent staining as previously described (Withers and Banker, 1998, in Culturing Nerve Cells, MIT Press). Briefly, cells were fixed (4% formaldehyde, 4% sucrose in phosphate buffered saline, pH 7.4), permeabilized with 0.25% Triton and immunostained MAP2 (HM2, from Sigma with d549 conjugated secondary, excitation, 555, emission, 568, Jackson Immunoresearch). Images were acquired with a Leica DMRA microscope with a 20X (Fluotar, NA 0.5) lens, Photometrics CoolSnap ES CCD camera and MetaMorph software.