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. Author manuscript; available in PMC: 2009 Nov 9.
Published in final edited form as: Nat Neurosci. 2008 Apr 20;11(5):565–571. doi: 10.1038/nn.2110

Figure 5.

Figure 5

Measurement of spontaneous isomerization rate of red cone pigment. (a–c) Top, same Rho+/+ Gcaps−/− rod (control). Bottom, same OPN1LW+ Rho+/+Gcaps−/− rod. See text and Methods for details. (a) Counting method. Sample recordings (continuous in time from top through bottom traces) in darkness showing discrete events (asterisks) identified based on a criterion amplitude of >30% of single-photon response. (b) Method based on power-density spectra. Difference power spectrum (spectrum with events minus spectrum without events) fitted by that for the single-photon response function. (c) Probability density method. Red profile, probability density histogram of overall dark recordings. Bin width, 0.1 pA. Blue profile is that of selected recording segments with no apparent events, scaled to the same height as the red profile. Black dashed curve, scaled gaussian distribution that fits the negative sides of the red and blue histograms. (d) Overlaid (and normalized to the same height) excess probability density histograms averaged from six Rho+/+Gcaps−/− (red) and six OPN1LW+ Rho+/+Gcaps−/− (black) rods to show their identical profiles. Top, linear coordinates; bottom, semilog. Bin width, 0.05 pA; error bars, s.e.m.