Fig. 5.

Identical photoresponses of WT and S100B KO mouse rods. (A) Averaged responses of a WT rod (upper panel) and an S100B KO rod (lower panel) to flashes. Maximal response amplitudes were 8.2 and 7.8 pA for the WT and S100B KO, respectively. Flash strengths were: 18, 33, 75, 142, 298, 564, 1244, 2357 and 4958 photons µm^-2 for both rods. Flash monitor is shown by the bottom trace. (B) Stimulus-response relations for the rods from A, WT (black symbols) and S100B KO (gray symbols). For illustrative purposes, some saturating responses are not shown. Results were fit with a saturating exponential function, r/r_max = 1- exp(−ki), where i is flash strength, k is equal to ln(2)/i_0.5, and i_0.5 is the flash strength that produces a half-saturating response. i_0.5 was 54 and 56 photons µm^-2 for the WT and S100B KO, respectively. (C) Pepperberg plot for WT (black symbols) and S100B KO (gray symbols) rods. The saturation time of a bright flash response was measured from mid-flash to the point at which the saturating response declined to 0.8 r_max, i.e., 20% recovery, as demarcated by the dotted lines in A. Values for τ_c, obtained from linear regression (continuous lines), were 252 ms for the 11 WT and 187 ms for 14 S100B KO. The Pearson product moment correlation coefficients for the WT and S100B KO rods were 0.64 and 0.39, respectively.