Approximately 100 mg of gray matter tissue from the dorsolateral prefrontal cortex (DLPFC) were sectioned while still frozen and shipped on dry ice overnight from the RADC to the Broad Institute. These sections were partially thawed on ice prior to dissection with a scalpel to separate the gray from the white matter and vasculature. Between 50 mg and 100 mg of gray matter was then added to 1 ml of Trizol and homogenized with a 5mm stainless steel bead for 30 s at 30 Hertz using the Qiagen TissueLyser II. Following a quick spin to settle the foam, we would invert the tube 2-3 times to observe if the sample was fully homogenized. If chunks of tissue were still observed the sample was put back in the TissueLyser for another round. Homogenate was incubated at room temp for 5 min and then frozen at −80 ˚C. Samples were later thawed and processed in batches of 12–24 samples for RNA extraction using the Qiagen MiRNeasy Mini (cat no. 217004) protocol, including the optional DNAse digestion step. This protocol yields total RNA
