high degree of neuronal morphology, expression of neuron-specific markers (MAP2 and TuJ 1, not shown), and evidence of synapse formation (Synapsin 1, Fig. 1C). To confirm the identity of the AD-iNs, we performed immunolabeling with antibodies specific for GAD67 (a marker for inhibitory GABAergic neurons), and found that both N40 and D40 AD-iNs stained positive for GAD67 (Fig. 1D). To further prove the neuronal identity of the AD-iNs used in this study, we employed whole-cell voltage clamp recordings to monitor miniature synaptic release (mIPSC) in the presence and absence of the GABAA antagonist picrotoxin (PTX) (Supplemental Fig. S1). Perfusion of PTX (50 μM) into the recording chamber completely abolished synaptic release, further confirming the inhibitory nature of the AD-iNs used in this study. Taken together, mature human-specific AD-iNs were successfully generated from isogenic human stem lines carrying MOR allelic variants.
