Figure 2

Intrinsic behavioral circadian rhythm is initially suppressed during constant dark exposure following FDN-G. Representative actograms of wheel-running activity during constant darkness following (A) 16:8 LD, (B) FDN-S, and (C) FDN-G. n = 6 per group. Recording of wheel-running activity commenced as indicated on actograms (mice were in preceding LD cycles as explained in the “Methods” and Supplementary Tables S1). The analysis for figures (A) and (B) are based on the first 7 days in DD. (D) Average of daily (across 7 days for all except FDN-G days 1–5) wheel-running activity, collected in 30-min bins, and normalized to the highest daily activity for each mouse. (E) Lomb-Scargle, Chi-square, and Wavelet periodograms averaged across 7 days for DD following 16:8 LD, FDN-S, and FDN-G; the average (black line) is plotted with ± SEM error bars. Alignment with the 24-h day indicated by the dotted red line. n = 6 per group, comparison between all groups for Lomb-Scargle: F = 9.52, P < 0.0001***, peak average amplitudes: 1671.82, 1132.36, 212.72, 740.94, Range: 1390.03, 1525.79, 399.08, 1369.8 and ± SEM: 228.28, 248.87, 57.56, 206.14. Chi-square: The dashed gray line indicates the significance line (0.05). F = 7.21, P < 0.002**, peak average amplitudes: 227, 153.8, 84.6, 189.1, range: 141.7, 182.88, 68.13, 149.33, and ± SEM: 24, 26, 10.6, 25.71. Wavelet: F = 2.88, P < 0.06, peak average amplitudes: 4542.83, 3338.5, 1924.5, 2702.67, Range: 5655, 4147, 2066, 3369 and ± SEM: 946.82, 670.24, 357.41, 473.52. (F) Average total wheel-running activity across 7 days. n = 6 per group, F = 1.33, P = 0.29, ranges: 867.4, 583.5, 739.9, 715.4 and ± SEM: 141.9, 76.94, 121.9, 118.4. (G) Circadian period (tau). The average tau at the peak amplitude of periodograms in “E” is graphed (x-axis) vs. the SEM of the tau for each experimental group (y-axis). The ± SEM error bars for the average tau are also displayed. Alignment with the 24-h day indicated by the dotted red line. n = 6 per group, Lomb-Scargle: F = 8.26, P < 0.001***, peak average tau: 23.56, 23.62, 14.29, 23.35, Range: 0.25, 0.25, 16.35, 0.55, and ± SEM: 0.04, 0.05, 3.1, 0.07. Chi-square: F = 3.1, P < 0.05*, peak average tau: 23.42, 23.66, 22.75, 23.66, Range: 1.5, 0.5, 3, 0.5, and ± SEM: 0.2, 0.1, 0.42, 0.1. Wavelet: F = 0.98, P < 0.42, peak average tau: 23.13, 23.69, 19.92, 23, Range: 0.5, 2.51, 21.14, 1.83, and ± SEM: 0.07, 0.39, 3.39, 0.31. (H) Assessment of the period of circadian-driven wheel-running activity using the Circadian Duration Index (CDI). n = 6 per group, F = 48.65, P < 0.0001***, and ranges: 4.50, 5.00, 5.00, 5.00 ± SEM: 0.66, 0.76, 0.69, 0.79.