Nuclei were isolated from frozen prefrontal cortex tissue using a lysis buffer of 0.25 M sucrose, 10 mM Tris-HCl pH 7.5, 5 mM MgCl2, 25 mM KCl, 0.1% Triton X-100, 1 mM DTT and 0.2 U/uL RNAse inhibitor (Protector, Sigma). Tissue was homogenised in 1 mL lysis buffer using a Nano pestle, incubated 5 min on ice and filtered through a 70 um strainer (MACS SmartStrainer, Miltenyi). Filtered samples were centrifuged at 500 g for 5 min at 4 C, resuspended in 1 mL lysis buffer, filtered through a 30 um strainer, centrifuged again at 500 g for 5 min at 4 C, and resuspended in PBS with 0.04% BSA. Nuclei were counted on a Countess 3 (Thermo Fisher). Four mouse-specific nuclei suspensions were tagged with 10x Genomics On-Chip Multiplexing (OCM) barcodes and pooled prior to loading. Libraries were prepared with the Chromium GEM-X Universal 3' Gene Expression kit v4 with 4-plex On-Chip Multiplexing (10x Genomics) according to the manufacturer's instructions, yielding one paired Gene Expression library per GEM well (tube).