(A-B) mIPSC frequency was strongly reduced in Cre-positive VTA dopamine neurons from Grin1f/f/DAT-Cre/tdTomatoCremice (Frequency: Grin1f/+ (1.59 ± 0.20 Hz, n = 21), Grin1f/f (0.61 ± 0.08 Hz, n = 22), p < 0.001, t-test; Amplitude: Grin1f/+ (−20.84 ± 0.79 pA, n = 21), Grin1f/f (−21.62 ± 1.26 pA, n = 22), p = 0.61, t-test). Cumulative distributions were compared by the Kolmogorov-Smirnov test (p ≥ 0.05 for amplitude and p < 0.001 for interevent interval). Scale bar: 20 pA and 1s.