Quantifying ARID1B Expression in Brain

Immunostaining of brain sections was performed as described previously^{61 (link),62 (link)}. The following primary antibodies were used: anti-Parvalbumin (Millipore, Rabbit, AB1572; 1:200), anti-Arid1b (Abcam, Mouse, ab57461; 1:200), anti-VIAAT (PhosphoSolutions, Rabbit, 2100-VGAT, 1:500), anti-VGLUT1 (Millipore, Guinea pig, AB5905, 1:1000), GAD2 (Developmental Studies Hybridoma Bank, Rat, GAD6, 1:200), and anti-Somatostatin (MilliporeSigma, Rat, MAB354; 1:200). 4′,6-diamidino-2-phenylindole (DAPI; Sigma; 1μg/ml) was used for counterstaining. Appropriate secondary antibodies conjugated with Alexa Fluor dyes (Invitrogen) were used to detect primary antibodies. All slides were visualized and imaged under FV3000 (Olympus) fluorescent confocal microscope system. To quantify ARID1B expression levels, we measured the intensity of ARID1B fluorescence in PV or SST positive cells using NIH ImageJ. The expression intensities were averaged and presented after background subtraction and normalization to those of PV or SST negative cells.