The protocol for generating GABAergic human AD-iN cells was described elsewhere (Yang et al., 2017; Halikere et al., 2019). Briefly, iPS cells were plated as dissociated cells on 1:100 Matrigel™ Matrix-coated plates in mTeSR™ medium with 5 μM ROCK inhibitor. Infection was performed in suspension. When iPS cells reached ~70% confluency, cells were passaged and re-plated, at ~33.3% ratio of total iPS cells collected following passaging, in mTeSR™ media containing the doxycycline-inducible lentiviruses expressing transcription factors (Ascl1 and Dlx2) and the reverse tetracycline-controlled transactivator (rtTA) at 37 °C, 5% CO2. Infection proceeded for approximately 6–7 h, upon which culture medium was replaced with Neurobasal™ medium (GIBCO by Life Technologies, catalog# 21103–049) containing B27 and l-glutamine supplemented with 2 μg/mL of doxycycline (MP Biomedicals, catalog# 198955) and 5 μM ROCK inhibitor to induce TetO expression. The protocol for generating lentiviruses was previously described (Yang et al., 2017). Puromycin (1 μg/mL; Sigma Aldrich, catalog# P8833) and hygromycin (50 ng/μL; Sigma Aldrich, catalog# H9773) selection was conducted for the following 2 days, and on day 5, the iN cells (~200,000 iNs/coverslip) were dissociated
