Fig. 1

PER2::LUC rhythms in dispersed SCN cells, SCN slices, and the SCN of freely moving mice. Per2 protein fusion luciferase activity was measured using bioluminescence imaging from dispersed (left) and slice (middle) SCN culture using an EM-CCD camera. Circadian rhythms of individual SCN cells in dispersed (lower left) and slice (lower middle) cultures are expressed as pseudo colors, in which red and blue indicate peak and trough circadian rhythm phases. PER2::LUC rhythms in the SCN in freely moving mice were measured using an optical fiber under constant darkness for 4 days. Neuronal networks are important for SCN cellular circadian rhythm synchronization. Scale bars represent 200 μm