**Figure 4. **Bioluminescence analysis of *Per1-luciferase* rat retina explants. **A**: Detrended bioluminescence recording (black line) from a representative explant cultured under protocol M0. Data were fitted
with a cosine curve (y = y0 + c·cos[2π(t-φ)/τ]) shown in gray, to calculate corresponding periods. **B**: Detrended bioluminescence recording (black line) from a representative explant cultured under protocol M1. Data were fitted
with a damped cosine curve (in gray; y = y0 + c·exp(-t/d)·cos[2π(t-φ)/τ]) to calculate the oscillation periods. **C**: Detrended bioluminescence recording (black line) from a representative explant cultured under protocol M2. Data were fitted
with a damped cosine curve (in gray) as in **B**. **D**: Composite graph showing averaged traces on the same scale and during three cycles, from samples within each treatment group
(n = 4 for M0, in light gray; n = 4 for M1, in gray; n = 7 for M2, in black). In panels **A**–**D**, the alternating rectangles at the top indicate the projection of the lighting schedule (black: 12 h dark; hatched: 12 h
light) to which animals were exposed before they were euthanized. **E**: Rhythmic power in cultures under protocols M0, M1, and M2. Mean values±standard error of the mean (SEM) are shown. * p<0.05;
*** p<0.001.