Figure 1.

Estimating membrane resistance and capacitance. Example voltage responses (black) from two different cells to a small hyperpolarizing current step (bottom; −50 pA, 200 ms) and the double-exponential fits (red) used to estimate membrane resistance (R _m), membrane capacitance (C _m), access resistance (R _p), and pipette capacitance (C _p). The first 20 ms of the responses (insets) show the separation between the fast (τ_p) and slow (τ_m) exponentials. a, A recording with relatively low access resistance compared with the estimated R _m (τ_m = 11.2 ms, R _m = 208 MΩ, C _m = 54 pF, R _p = 58 MΩ, τ_p = 0.22 ms, C _p = 3.8 pF). b, A recording of just-acceptable quality (same cell as Fig. 4): the access resistance was slightly smaller than the estimated R _m (τ_m = 10.3, R _m = 168, C _m = 61, τ_p = 0.34, R _p = 147, C _p = 2.3).