To isolate individual RFP-labeled GABAergic neurons, we microdissected motor and somatosensory cortical slices from fresh brain tissues of mature (6 weeks old) mice, generated single cell suspension and manually purified single RFP-labeled cells (Sugino et al., 2006). Brains were sectioned at 300 μm thickness using a cooled stage vibratome (Microm, Model HM360) with circulating oxygenated artificial cerebrospinal fluid. Sections were blocked in AP5, CNQX, and TTX cocktail to prevent excitotoxic cell death and then treated with mild protease (Fraction IV protease Streptomyces, Sigma Cat#P5147-5G). Brain regions of interest were microdissected and triturated to dissociate the cells. Dissociated cells were put into in a Petri dish in low density for optimal cell-cell separation then purified progressively by transferring RFP cells to fresh plates 3 times. Finally single RFP-positive cells was collected using patch pipette capillary and dispensed individually into separate single tubes prefilled with RNAseOUT (Invitrogen), ERCC spike-in RNAs in 1:400 K dilution, sample specific RT primers for a total of 1 μL volume. Process was repeated to collect 32–64 cells in one manual cell sorting session. Cells were flash frozen
