Fig. 1
GABAergic synapses onto pyramidal-cell dendrites activate α5-GABAARs. a Experimental design. Targeted projections from local interneurons are indicated. b IPSCs evoked by electrical stimulation in different layers (SLM stratum lacunosum moleculare, SR stratum radiatum, SP stratum pyramidale) were recorded at –70 mV in the presence of 10 µM NBQX and 25 µM AP5 using a CsCl-based pipette solution. Representative mean IPSCs before (black) and after addition of the α5-NAM RO4938581 (1 µM, blue) show that only IPSCs evoked in the dendritic layers were sensitive to the α5-NAM. c Group means of the normalized α5-NAM-sensitive component in SLM-evoked IPSCs (P < 0.01; one sample t test, n = 6) and SR-evoked IPSCs (P = 0.085; Wilcoxon signed rank test, n = 11). d The mean decay time constant of single IPSCs evoked in different layers of CA1 was not affected by the application of the α5-NAM. e Brief-burst stimulation (5@50 Hz) of putative dendritic (SLM) and perisomatic (SP) IPSCs before and after (blue) application of the α5-NAM (1 µM, blue). f Effect of 200 nM gabazine on burst IPSCs. g Top, bar graph showing that application of the α5-NAM reduced the IPSC burst integral of SLM- (P < 0.01; paired t test, n = 6) and SR-evoked IPSCs (P < 0.01; n = 11), whereas somatic IPSCs evoked in SP remained unaffected (P = 0.35; n = 10). Conversely, gabazine-induced reductions (200 nM) were significantly smaller in SLM- than in SR- or SP-evoked IPSCs (both: P < 0.01; Mann–Whitney test). Bottom, the α5-NAM reduced the burst IPSC decay τ in all three cases (all: P < 0.05; paired t test). Recording temperature ≈ 33 °C
