Figure 9.

Increase in GABA_BR-mediated conductance at distal dendrites reduced glutamate-evoked excitation via shunting inhibition in WFV cells. A, Reconstruction of a biocytin-filled WFV cell showing the locations of recoding electrode (Rec) and puff pipettes for application of glutamate (Glu puff) and baclofen (Bac puff). DS, Dorsal surface of the slice. B, Local glutamate application (Glu, 1 mm, 10 psi, 30 ms) into the SGS, dendritic fields of the WFV cells, evoked depolarization (B1, Glu) in the presence of TTX (1 μm) and gabazine (10 μm). Baclofen (1 mm, 10 psi, 60 ms) applied 20 μm away from the glutamate application site evoked a slight hyperpolarization (B2, Bac). Glutamate application preceded by baclofen application (100 ms) elicited a smaller depolarization than glutamate application alone (B3, Bac Glu). This baclofen effect was blocked by CGP bath application (B4, Bac Glu in CGP). Note that the amplitude of depolarization evoked by combined application of glutamate and baclofen (B3) is smaller than the amplitude of the digital sum of the traces obtained from puff application of glutamate and that of baclofen (B5). The recordings were obtained from the cell shown in A. C, A summary graph showing that the amplitude of depolarization elicited by glutamate puff application was reduced by the preceding baclofen puff application. *p < 0.05.