Measured and modelled photocurrent of ground squirrel cones in response to flashes of different strength. The symbols are sampled data points extracted from the curves plotted in the first figure of , and represent the cone current as a fraction of the circulating dark current (estimated as 67 pA from the fitting). The curves plot the predictions of the model for the normalized current J(t)/J(0), using the values of parameters listed in Table 1. The membrane capacitive time constant was set to τm = 2.3 ms, while all other parameter values were obtained from the fitting. The parameter kβ is specified in different units for this experiment, corresponding to the units in which the flash intensities were specified; these flash intensities increased in factors of 2 from 630 to 3.2·105 photoisomerizations per flash (using an effective collecting area of 0.64 μm2 ). The flash duration was 11 ms, and here we have plotted the time origin with respect to the start of the flash (whereas it was plotted relative to the mid-point of the flash in ).