GABA_B receptor activation reduces mitral cell recurrent inhibition. Top, Individual records from one mitral cell (V_m = −70 mV, KCl internal solution). A brief train of depolarizing voltage steps (2 msec, +70 mV, 7 pulses) elicits action currents, followed by a long-lasting barrage of synaptic currents (Control). The synaptic response is reduced after bath application of the GABA_B agonist baclofen (50 μm). Switching to a solution containing the GABA_B antagonist CGP 55845 (5 μm) reverses the action of baclofen. Subsequent application of the GABA_Aantagonist bicuculline methiodide (20 μm) abolishes the synaptic response (+BMI). Bottom, Summary plot of the results for 11 cells. Points represent the average of two consecutive responses evoked every 30 sec. The dashed line represents unity. Inset, Recording configuration. MC, Mitral cell; GC, granule cell.