library_construction_protocol: Fresh frozen tissue from postmortem brain was cryosectioned (approximately 40 sections of 40 µm thickness each) and lysed in sucrose lysis buffer (10 mM Tris HCl (pH 8.0); 320 mM sucrose; 5 mM CaCl2; 3 μM Mg(Ac)2; 0.1 mM EDTA; 1 mM dithiothreitol (DTT) and 0.1% Triton X-100). Lysates were filtered through a 70 µm cell strainer. Nuclei were purified by ultracentrifugation (107,000 × g for 1.5 h at 4 °C) through a sucrose cushion (10 mM Tris –HCl (pH 8.0); 1.8 M sucrose; 3 μM Mg(Ac)2; 0.1 mM EDTA and 1 mM DTT). Supernatants were removed and pellets were resuspended in 2% BSA/PBS containing RNase inhibitor (0.2 U/μL) (Roche). Nuclei were incubated with fluorescently conjugated antibodies against the neuronal marker NEUN (RBFOX3/NEUN (1B7) APC mouse mAB, Novus Biologicals) and the oligodendrocyte transcription factor OLIG2 (Anti-OLIG2 clone 211F1.1 mouse mAb, Merck Millipore, MABN50A4). Samples were kept on ice throughout the isolation and staining procedure. Nuclei were stained with Sytox blue (Thermo Fisher) and sorted on a Sony SH800. For each sample, we collected Sytox+NeuN-Olig2- nuclei. Single nuclei libraries were prepared using 10x Genomics, Chromium Single Cell 3', v3 chemistry, and sequenced on an Illumina HiSeq2000 targeting at least 20k reads per nuclei.