Figure 3. Accuracy of ΔC_m estimates as a function of location of capacitance increase investigated by computer simulation.

A, shape plot of morphologically reconstructed rod bipolar cell used for computer simulations (same cell as in Fig. 1). Red arrow indicates position of idealized single-electrode voltage clamp (SEClamp) connected to one of the axonal endings (T1) of the axon terminal. ΔC_m of 107 fF (corresponding to an increase in surface area of 10 μm² with specific capacitance 1.07 μF cm⁻²) simulated at three different axonal endings (T1–T3) or three different positions in the axon terminal (A1–A3; indicated by white circles). ΔC_m estimated by 2 kHz sine wave stimulation (±15 mV from V_hold=−80 mV). B–D, estimates of ΔC_m (B), ΔR_s (C) and ΔR_m (D) as a function of location of capacitance increase, indicated as distance between the electrode (located at T1) and the location of capacitance increase.