Total RNA was isolated from mouse brain tissue with TRIzol (Invitrogen) From total RNA, poly-A RNA was purified by removing rRNA using Epicentre's Ribo-Zero rRNA Removal kit (Cat# RZH11042). library preparation using TruSeq Standed Total RNA Kit (Illumina): Double stranded cDNA fragments are ligated with Illumina paired end adaptors, followed by size selection (~200bp). need confirmation by Scott Olson