Figure 3. Reduced FFI in the MD–mPFC circuit in Disc1 LI mice. A, B, Schematics of the experimental configuration. The right panel of A is an image of a brain section from a mouse used in electrophysiological recording, showing MD infected with AAV-CAG-ChR2-YFP. C, Representative traces of evoked EPSC (recorded at –60 mV) and IPSC (recorded at 0 mV) from L3 PNs. D, To estimate the relative recruitment of disynaptic FFI versus monosynaptic excitation, we divided peak IPSC (Ipeak) by the sum of peak IPSC and peak EPSC (Ipeak + Epeak). WT, N = 14 mice, Disc1 LI, N = 11 mice; ***p < 0.001, t test. E, Same as in D, except that the cumulative probability distributions of the values for individual neurons are shown. WT, n = 40 cells, Disc1 LI, n = 30 cells; **p < 0.01, Kolmogorov–Smirnov test. F, Scatter plot showing the peak amplitudes of IPSC and EPSC for individual neurons. Each circle represents one neuron (WT, n = 30 cells; Disc1 LI, n = 40 cells). Dashed lines are linear regression lines for neurons in WT mice and Disc1 LI mice. The slopes of the regression lines significantly differed at the 0.95 confidence level (*p < 0.05). G, Sample traces of IPSC (recorded at 0 mV) and EPSC (recorded at –60 mV) recorded from L2/3 PNs in response to light-stimulation (blue bars) of MD axons. The latency to onset was measured from the time the light stimulus was triggered to the 10% EPSC (blue arrow) or IPSC (red arrow) rise time. Note that IPSC rise time was calculated from the peak of the inward current recorded at 0 mV. H, Cumulative probability distributions for EPSC latency to onset (left) and IPSC latency to onset (right; EPSC, WT, n = 40 cells, Disc1 LI, n = 30 cells, p = 0.40; IPSC, WT, n = 40 cells, Disc1 LI, n = 30 cells, p = 0.56; Kolmogorov–Smirnov test). I, Quantification of IPSC–EPSC lag, calculated as the difference in the latency to onset between the IPSC and the EPSC of each neuron (see also G; WT, n = 40 cells, Disc1 LI, n = 30 cells; p > 0.05, t test). J, Quantification of the 10–90% EPSC rise time and decay tau (K; WT, n = 40 cells, Disc1 LI, n = 30 cells; p > 0.05, Mann–Whitney U test). L, Quantification of the 10–90% IPSC rise time and decay tau (M; WT, n = 40 cells, Disc1 LI, n = 28 cells; p > 0.05, t test). Data are presented as median ± interquartile range (J, K) or mean ± SEM (D, L, M).