FIGURE 2.

Models that cannot be discriminated by one-dimensional dwell-time distributions can be resolved by high-order dwell-time distributions, but they may remain as local maximum solutions. (A) The two-dimensional dwell-time distribution predicted from Scheme II for Ca²⁺-activated potassium channels. The existence of coupling between closed and open dwell-times is evident from the different appearances of the one-dimensional open dwell-time distributions in adjacency to different closed durations. (B) Contours of the likelihood surface at the true solution (top) and a local maximum point (bottom). Each interval corresponds to 918 (top) and 38,835 (bottom) log likelihood units, respectively. The local maximal solution is inferior to the true one by ∼4000 units. The axes represent the logarithms of the ratios of the rates to their true values used in simulation (top) or to their local maximum solutions (bottom). (C) The one-dimensional dwell-time distributions predicted by the local maximal solution. It fits well both closed and open histograms. The dotted lines represent the individual components. A dead time of 40 μs was used for all analysis except for the plot of the theoretical two-dimensional dwell-time distribution in A.