Functional analyses of iN cells were conducted using whole cell patch-clamp as described elsewhere 24, 29. Briefly, a K-Gluconate internal solution was used, which consisted of (in mM): 126 K-Gluconate, 4 KCl, 10 HEPES, 4 ATP-Mg, 0.3 GTP-Na2, 10 Phosphocreatine. The pH was adjusted to 7.2 and osmolarity was adjusted to 270-290 mOsm. The bath solution consisted of (in mM): 140 NaCl, 5 KCl, 2 CaCl2, 2 MgCl2, 10 HEPES, 10 Glucose. The pH was adjusted to 7.4. Spontaneous inhibitory postsynaptic currents (sIPSCs) were recorded either at a holding potential of 0 mV under voltage-clamp mode or at a −70 mV holding potential with 20 ¼M CNQX added to the perfusion solution. Miniature IPSCs (mIPSCs) were recorded in the presence of tetrodotoxin (1 ¼M). Intrinsic action potential firing properties of the iN cells were recorded in a bath solution containing 50 ¼M Picrotoxin and 20 ¼M CNQX. Evoked synaptic currents were elicited using an extracellular concentric bipolar stimulating electrode positioned approximately 100 ¼m away from the cell soma. All recordings in cultured human neurons were performed at room temperature because
