A and B, voltage-clamp recordings of mIPSCs of inspiratory PBC neurones in the presence of CNQX (20 μm), AP5 (20 μm) and TTX (1 μm) at P0 (A) and P8 (B) before (1), in the presence (2) and after application of baclofen (2 μm, 3). The holding potential was −70 mV. C and D, cumulative amplitude histograms before and after the application of baclofen in P0-P3 (P≤ 0.01, n = 5) and P7-P15 (P≤ 0.05, n = 5) slices. E and F, cumulative interval histograms before and after the application of baclofen in P0-P3 (n.s., n = 5) and P7-P15 (P≤ 0.01, n = 5) slice preparations.