Our Visual System Has a Remarkable Dynamic Range

Our visual system has a remarkable dynamic range. When you go to a matinee movie (during the daytime) and walk out of the theater it is difficult to see. After a few minutes your eyes adapt to the new light levels. Some of the molecular mechanisms of light adaptation are known and most involve changes in Ca²⁺ concentration. (A)


(B)

Figure Q4-13
A. Based on the data from the experiments shown in Figure Q4-13, what is one mechanism of adaptation? Figure Q4-13A shows the dark-adapted response to a flash of light in wild type and GCAP knockout mice. Figure Q4-13B shows the rod response to a flash of light relative to the same flash after dark adaptation.
B. What is the probable molecular mechanism of reduced light adaptation involving GCAP?