library_construction_protocol: At least 10 – 20 mg of frozen tissue was obtained from each sample using a metallic block and hammer to take a portion of the dissected cortex tissue. The tissue was then sealed inside of a Covaris Tissue TUBE (Covaris, cat. Nos. 520021 and 520023) and thoroughly pulverized using the chilled hammer and metallic block, with intermittent submerging into liquid nitrogen to maintain cold temperature and brittleness. Using a clean, pre-chilled scoopula, pulverized tissue was then transferred to a pre-chilled 2 mL DNA LoBind tube. RNA was isolated using the miRNeasy Mini Kit according to manufacturer instructions (QIAGEN, cat. no. ​217084). Approximately 100,000 NeuN+ nuclei were sorted into 650 μL cold Trizol for RNA isolation. RNA isolation was performed using the Direct-zol RNA microprep kit  (Zymo Research. cat. no. R2060) per manufacturer instructions. Sequencing libraries were prepared following the SMARTer Stranded Total RNA-seq Kit v2 – Pico Input (Takara Bio, cat. no. 634411).