library_construction_protocol: Frozen mouse cortical tissues (n = 2) were received at Azenta (GENEWIZ, LLC.; South Plainfield, NJ, USA) on dry-ice and stored in liquid nitrogen upon receipt until further processing. Intact nuclei extraction was performed using the Miltenyi Nuclei Extraction Buffer (Miltenyi Biotec, Auburn, CA, USA) following manufacturer's guidelines with gentle MACS Dissociation and C tubes. Upon isolation, the nuclei were counted using AO/PI dye on the Nexcelom Cellaca MX. ATAC-seq library preparation and sequencing reactions were conducted at GENEWIZ, LLC. (South Plainfield, NJ, USA). Live cell samples were thawed, washed, and treated with DNAse I (Life Tech; EN0521) to remove genomic DNA contamination. Live cell samples were quantified and assessed for viability using a Countess Automated Cell Counter (ThermoFisher Scientific, Waltham, MA, USA). After cell lysis and cytosol removal, nuclei were treated with Tn5 enzyme (Illumina; 20034197) for 30 minutes at 37°C and purified with Minelute PCR Purification Kit (Qiagen; 28004) to produce tagmented DNA samples. Tagmented DNA was barcoded with Nextera Index Kit v2 (Illumina; FC-131-2001) and amplified via PCR prior to a SPRI Bead cleanup to yield purified DNA libraries. The sequencing libraries were validated on the Agilent TapeStation (Agilent Technologies, Palo Alto, CA, USA), and quantified by using Qubit 4.0 Fluorometer (Invitrogen, Carlsbad, CA), as well as by quantitative PCR (KAPA Biosystems, Wilmington, MA, USA). Illumina reagents and kits for DNA library sequencing cluster generation and sequencing were used for sequencing of the enrichment libraries. Libraries were multiplexed on a flow-cell and loaded onto the Illumina NovaSeq instrument according to the manufacturer's instructions.