library_construction_protocol: 10x Genomics protocol. Briefly, hippocampi were chopped into small pieces and dissociated with enzyme mixes in a Neural Tissue Dissociation Kit (P) (Miltenyi 130-092-628) in the presence of actinomycin D. After dissociation, cells were resuspended in Hibernate A Low Fluorescence medium (Brainbits) containing 5% FBS, with Calcein Violet AM (Thermo Fisher C34858) and propidium iodide (Thermo Fisher P1304MP). Flow cytometry was used to sort and collect live single-cell suspensions for the single-cell RNAseq study. Sample processing and library preparation was carried out using the Chromium Next GEM Automated Single Cell 3' Library & Gel Bead Kit v3.1 on the Chromium Connect Instrument according to manufacturer's instructions. Live cell samples were  prepared to target 10,000 cells per sample and loaded to the instrument. Libraries were sequenced with HiSeq 4000 (Illumina).