For experiments investigating neuronal cell density (Fig. 1C, S3B), lentiviral transduction of synapsin-1 promoter-driven mCherry tagged with nuclear localization signal (FSW-mCherry-NLS) was used to label all neuronal nuclei in the cultures. Epi-fluorescent live imaging was taken by Leica microscope coupled with digital camera DFC400 (Leica) and analyzed using ImageJ software (National Institutes of Health).
