Laminar distribution of GABABR-mediated currents in hippocampal principal cells. (A, left) Reconstruction of a CA1 PC. Soma and dendrites are shown in black and the axon in red. Inset, Voltage responses to a family of hyper- to depolarizing current pulses (–250 to +500 pA, 50 pA steps). A train of APs was elicited at the largest step. (A, middle) Representative pharmacologically isolated GABABR-mediated uIPSCs in the different layers (L-M: str. L-M; Rad: str. radiatum; Pyr: str. pyramidale; Ori: str. oriens). Baseline is indicated by a gray dashed line, (A, right) Summary bar chart illustrates the mean uIPSC amplitudes for each layer (n = 11). (B, left) Reconstruction of a CA3 PC with the same layout as in (A) with the inset. (B, middle) GABABR-mediated uIPSCs from a CA3 PC for the various layers (Luc: str. lucidum). (B, right) Summary bar chart of the mean uIPSC amplitudes for CA3 PCs (n = 12). (C, left) A reconstructed DGC, with intrinsic physiological response as inset. (C, middle) Representative GABABR uIPSCs recorded from a DGC evoked in the different layers (GCL; iML, inner ML; mML, medial ML; oML, outer ML). (C, right) Summary bar chart of the mean uIPSC amplitudes for DGCs (n = 12). Bars for the mean values are overlain by data from individual experiments (color coded circles and lines). Statistics shown: ns = P > 0.05, ***P < 0.001; one-way ANOVA.