Figure 5. Dynamics of dark sensitivity recovery after short-term light adaptation. A continuous series of 0.3 s stimuli was presented in the dark. Short-time light adaptation was achieved by using 2 s adapting stimuli (denoted by bars under the time scale). A: Dynamics of sensitivity recovery of the ON transient (left), ERG receptor component (in the middle) and OFF transient (right) in the wild-type flies (black squares; n=17), and hclB^T2 null mutant (red circles; n=15). Test stimulus intensity I_t)=4.73 log quanta s⁻¹ μm⁻²; background intensity I_b)=6.66 log quanta s⁻¹ μm⁻²_. While instant sensitivity recovery of the ON and OFF transients is seen in wild-type flies, the sensitivity recovery in the hclB^T2 mutants is delayed (two way analysis of variance [ANOVA], p=7.42.10⁻¹⁰ for the ON response and p=6.8.10⁻⁸ for the OFF response in these particular conditions). B: Postadaptational potentiation of the ON transient in the wild-type-flies (n=22) obtained using the following combination of test and adapting stimuli: I_t=4.73 log quanta s⁻¹ μm⁻², I_b=6.16 log quanta s⁻¹ μm⁻². Postadaptational potentiation is lacking in the hclB^T2 (n=19) mutant flies. All labels are as in A. C: Original electroretinogram (ERG) records, obtained from a wild-type control fly (in the middle), hclB^T2 mutant (on the left), and hclB^T1 mutant (on the right). Stimulation conditions are as in B, In the first few seconds after the termination of the 2 s light-adapting stimulus, a postadaptational potentiation is seen in the wild-type fly, while a delayed sensitivity recovery is seen in the two mutants.