Figure 4.

Quantification of P_r, N, and Q. A, C, Example experiments showing effects of different Ca_e on EPSC amplitude over the course of the experiment from a control mouse (P22, A) and an occluded mouse (P23, C). Lines above the points indicate the data that are used for analysis. B, D, Markers indicate variance versus EPSC amplitude for each Ca_e concentration from experiments in A and C. Lines are fits to the equation σ² = Qμ − (μ²/N), with N = 81 and Q = 108 in B, and N = 70 and Q = 90 in D. From these, P_r at 1.5 Ca_e is calculated to be 0.39 in B, and 0.64 in D. E–G, Cumulative frequency plot of N (E), P_r (F), and Q (G) from control mice (9 cells, black) and occluded mice (16 cells, red). After occlusion, N significantly decreased and P_r significantly increased (p < 0.05). Q showed no significant changes (p > 0.1). H, J, Representative long trains recordings in the presence of 1 mm kynurenate from a control mouse (H) and an occluded mouse (J) in response to stimulation of a single AN fiber (100 Hz, 45 pulses). I, K, EPSC amplitude is integrated, and a fit is extrapolated back from the last 20 cumulative EPSCs to the y-axis to estimate N (straight line). P_r is calculated by dividing the first EPSC by N. L, M, Quantification of N (L) and P_r (M) using the integration method from control mice (11 cells) and occluded mice (10 cells). Occluded endbulbs showed significantly smaller N (*p < 0.05) and higher P_r (*p < 0.05).