Selective stimuli elicit GABA_A,fastand GABA_A,slow. Photomicrograph (right column) of a CA1 pyramidal cell in a 400 μm slice taken from a 29-d-old rat and the monosynaptic GABA_A IPSCs recorded in this cell at 35°C that were evoked by stimuli in stratum pyramidale and stratum radiatum (left column). Five superimposed traces are shown for each stimulus location. The recording electrode can be seen entering the field of view from the top right and contacting the cell body. The apical dendrite of this cell is marked by the arrowheads. A stimulating electrode placed in stratum pyramidale just apical to the cell body evoked GABA_A,fast (left column, top traces), which had kinetics and amplitude similar to spontaneous events recorded in this cell. A second stimulating electrode placed next to the dendrite in stratum radiatum evoked GABA_A,slow (bottom left), the kinetics of which were clearly distinct from the overlying spontaneous IPSCs. Stimulus artifacts were removed off-line for clarity. Scale bar, 20 μm.