a, Only SAPAP3 mRNA is highly expressed in the striatum (STR). b, Cortico-striatal field potential recordings of acute brain slices show decreased fEPSPs in SAPAP3-/- mice. p< 0.001, repeated measures ANOVA. Inset shows a typical field recording (black trace) and sensitivity to NBQX (red trace). NP1, negative peak 1. c, Paired-pulse ratios (slope fEPSP#2/slope fEPSP#1) are similar between wildtype and SAPAP3-/- mice. d, Example traces of NMDAR-dependent fEPSPs recorded in the presence of 50 μM NBQX, 0 mM Mg2+ and 2 mM glycine. Sensitivity to APV indicated by red trace. e, NMDAR fEPSP area is increased in SAPAP3-/- mice. *p < 0.05, two-tailed t-test; number of recordings in parentheses.