Standard electrophysiology was performed as described by Vierbuchen et al.31 and Pang et al.29 Whole-cell patch clamp recordings were made in the neurons located in the central chamber. The bath solution contained (in mM) 140 NaCl, 5 KCl, 2 MgCl2, 2 CaCl2, 10 HEPES and 10 glucose (pH 7.4, adjusted with NaOH). The whole-cell pipette solution contained (in mM) 126 K-Gluconate, 4 KCl, 10 HEPES, 0.3 Na-GTP, 4 Mg-ATP and 10 Phosphocreatine (pH 7.2, adjusted with KOH). Both current and voltage clamp experiments were performed. For the current clamp experiment, spontaneous action potentials were recorded at resting membrane potential; for evoked stem current clamp recordings (steps of 5 pA from −20 pA to 35 pA), negative currents were injected to keep the membrane potential at around −60 mV. For voltage clamp experiments, spontaneous postsynaptic currents (PSCs) were recorded at a holding potential of −70 mV; whole-cell current responses were collected by a step depolarization protocol (step voltage injections were given from −100 mV to 0 mV with a step size of 10 mV).
