(A) Left: Effect of CNO on Vm. Scale bars: 5 mV, 3 min. Right: CNO hyperpolarizes mCitrine+ cells in both mouse lines (pSst = 0.017, pPV = 0.031, one-sample t-test, nSst = 7, 4, nPV = 6, 3). (B) IPSC is delayed relative to EPSC (paired t-tests: pSst-Ctrl = 0.0018, pSst-CNO = 8.80 x 10−4, pPV-CNO = 0.0042, pWT-CNO = 0.0012; Wilcoxon signed-rank tests: pPV-Ctrl = 2.44 x 10−4, pWT-Ctrl = 0.0024; nSst = 13, 6, nPV = 13, 7, nWT = 12, 6). (C) CNO- mediated Sst+ IN inactivation reduces FFI (Sst-hM4Di mouse line; Wilcoxon signed-rank tests: pIPSC = 0.040, pIE = 0.013, n = 13, 6). Top: Experimental schema, IPSC traces with and without CNO. Arrowheads: stimulation artifacts (truncated). Scale bars: 100 pA, 50 ms. (D) PV+ IN inactivation has no effect on FFI (paired t-tests: pIPSC = 0.35, pIE = 0.85, n = 13, 7). Display as for (C), but in PV-hM4Di mouse line. Scale bars: 25 pA, 50 ms. (E) CNO has no effect on FFI in wildtype littermates (Wilcoxon signed-rank tests: pIPSC = 0.73, pIE = 0.68, n = 12, 6). Display as for (C), but in hM4Di-/- littermates of Sst- and PV-hM4Di mice. Scale bars: 50 pA, 50 ms. Summary statistics in A, B (Sst-hM4Di both conditions, PV-hM4Di CNO condition, WT littermates CNO condition), and D in color as mean ± s.e.m. Summary statistics in B (PV-hM4Di and WT littermates control conditions), C, and E in color as median with IQR. *p < 0.05, **p < 0.01, ***p < 0.001. See Figure 5—figure supplement 1 for lack of effect of IN inactivation on EPSCs. See Figure 5—source data 1 for a table with full details on all statistical tests used in this figure. See Figure 5—source data 2 for a table of all individual data points displayed in Figure 5 and corresponding figure supplements.