Figure 2.

The ohmic and the ACF methods for estimating synaptic inputs illustrated on transected sample data. A, The ohmic method requires at least two trials connecting V_m and current injection (I_inj) to estimate G_tot. Shown here are three trials each with constant but different I_inj. The onset of tactile induced motor behavior is indicated (▴). B, A low-pass filtering of the traces gives an I/V relationship as a function of time (indicated for two time points) where the slope is G_tot. C, The resulting time-dependent G_tot (gray), G_inh (magenta), and G_exc (cyan) using Eqs. 3 and 4. D, Linearity should be confirmed, for instance, by plotting the estimates for different depolarizations against each other. E, The ACF method. The total conductance is estimated via the membrane time constant (G_ACF = C/τ_m), which is estimated via autocorrelation decay. F, The estimates of the total conductance using the two methods have a significant correlation (r = 0.64, p ≪ 0.001). [Adapted from Berg and Ditlevsen (2013) with permission.]