Fig. 8. GluR cells also receive glutamatergic input. Spontaneous (A₁-A₅) and evoked responses (B₁,B₂) were obtained from the same individual cell at p 10 (V_rest=–86 mV, R_i=230 M, C_m=73 pF). (A₁-A₄) After application of bicuculline (10 µM), only the fast events persisted. (A₂) represents mean sPSCs with slow (top, 5.6 pA, =21.6 milliseconds, n=2) and rapid kinetics (bottom, 8.6 pA, =4.4 milliseconds, n=2) at higher resolution, taken from trace in (A₁) before bicuculline application (i.e. under control condition). The sPSC in (A₃) was taken from the trace in (A₁) during bicuculline application and displayed on a fast time scale and larger current scale. (A₄) shows the mean of 29 sPSCs taken from the trace in (A₁) during bicuculline at higher resolution [5.7±1.8 pA, =3.6 milliseconds, rise time 1.1 milliseconds (10-90%), half width 4.8 milliseconds]. (A₅) represents the continuation of the trace in bicuculline shown in (A₁), 15 minutes later. Note the presence of spontaneous, bicuculline-insensitive activity before and shortly after additional wash-in of NBQX (10 µM) and D-APV (25 µM). Two minutes after co-application of bicuculline with NBQX and APV, spontaneous activity completely disappeared. (B₁) In the same cell, near-field stimulation evoked bicuculline-resistant ePSCs with kinetics similar to the sPSCs (A₃,A₄). Paired pulses (n=119; 150 microseconds, 8V, 50 milliseconds delay, 1 second interstimulus interval) were applied, and currents were sorted and averaged as described in Fig. 6B. In 32 cases, both pulses evoked glial PSCs (upper left trace; amplitudes 6.7 and 6.9 pA; =1.5 milliseconds) while 29 paired pulses produced double failures (right, top). 21 stimulation pairs induced responses upon the first (left, bottom), another 37 upon the second pulse (right, bottom). The total failure rate was 49%. (B₂) Co-application of bicuculline with NBQX (10 µM) and D-APV (25 µM) led to a complete block of ePSCs. [Cl^–]_i was always 27 mM.