Figure 1.

SCN-driven light-entrainable activity rhythm is only slightly attenuated in N-Bmal1^−/− mice. A, Representative locomotor activity of one control and two N-Bmal1^−/− mice. Animals were initially housed in LD conditions and then transferred to DD. Figure shows typical examples of activity rhythm of N-Bmal1^−/− mice. Timing of LD cycle is indicated by horizontal bar above each record; dark bars indicate lights off, and open bars indicate lights on. B, C, Periodogram estimates of free-running period (B) and circadian amplitude (C, power from periodogram analyses) of control (black bars) and N-Bmal1^−/− mice (white bars) during the last 10 d in DD. In C, value of each individual mouse is dot-plotted. *p < 0.05 by unpaired Student's t test. Values are mean ± SEM (n = 12 for control, n = 11 for N-Bmal1^−/− mice).