To characterize the AMD-iN cells, we performed RNA-seq on human AMD-iN cells cocultured with mouse glia for 4 weeks and computationally eliminated the mouse reads. AMD-iN cells robustly expressed markers of telencephalon such as FOXG1; whereas markers of the midbrain, hindbrain and spinal cord were largely absent (Supplementary Fig. 3). Numerous genes known to be expressed in GABAergic neurons15 and involved in GABAergic interneuron identity, maturation and function— such as DLX1/5/6, GAD1/2 and vGAT—were highly expressed in AMD-iN cells; transcripts of excitatory neuron genes vGluT1/2 were almost undetectable (Supplementary Fig. 3). The bulk of forebrain GABAergic neurons are generated in the medial, lateral and caudal ganglionic eminences (MGE, LGE and CGE); and we found markers of all three compartments expressed in AMD-iN cells (e.g., NKX2-1, LHX6, MAFB, MAF, NR2F2 and SP8). We also detected robust expression of gene sets characteristic of some MGE- and CGE-derived cortical interneurons (cINs), olfactory bulb interneurons, striatal projection neurons, retinal cells, prethalamic reticular nucleus cells and inhibitory cells derived from the zona limitans (zli) (Supplementary Fig. 3). Cortical interneurons are conventionally categorized based on neuropeptide
