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. Author manuscript; available in PMC: 2015 Dec 30.

Published in final edited form as: J Pineal Res. 2014 Feb 19;56(3):254–263. doi: 10.1111/jpi.12118

Fig. 2 — Melatonin resynchronizes forced-split locomotor activity. Animals were subjected to T-cycles of 22 hr with 11 hr of light and 11 hr of dim light. (A and E; Left) Representative actogram for mother-reared and peer-reared individuals treated with vehicle while subjected to 11:11 hr light:DimLight (LDim) conditions for 6 wk (stages 1 and 2). The individual was continued on vehicle alone treatment for an additional 8 days under constant dim light conditions (stage 3). (B and F) Corresponding chi-square analysis for the periodogram for stages (1–3) demonstrating the split spontaneous locomotor activity rhythms in stages 1 and 2 and lack of entrainment to the 11:11 hr LDim cycles as demonstrated in stage 3 where chi-square analysis reveals a single significant dominant peak with a period of 23.9 hr. (C and G) Representative actograms for mother-reared and peer-reared individuals subjected to 11:11 hr LDim conditions for 6 wk (stages 1 and 2) during which the individual was treated first with vehicle (ethanol; stage 1) followed by melatonin during stage 2. Finally, during stage 3, melatonin was replaced by vehicle under conditions of constant dim light for 8 days. (D and H) Corresponding chi-square analysis for periodograms of stages 1–3, demonstrating two spontaneous locomotor activity rhythms in stages 1 and 2 in case of vehicle treatment and the entraining effect of melatonin treatment in stage 2 as shown by chi-square analysis. Locomotor activity rhythms with a confidence level of 99.9% were considered as statistically significant. The periods (inserts) were indicated where rhythmicity was significant. Oblique lines indicate significance (P = 0.01). Qp values above the line are statistically significant.

Fig. 2 — Melatonin resynchronizes forced-split locomotor activity. Animals were subjected to T-cycles of 22 hr with 11 hr of light and 11 hr of dim light. (A and E; Left) Representative actogram for mother-reared and peer-reared individuals treated with vehicle while subjected to 11:11 hr light:DimLight (LDim) conditions for 6 wk (stages 1 and 2). The individual was continued on vehicle alone treatment for an additional 8 days under constant dim light conditions (stage 3). (B and F) Corresponding chi-square analysis for the periodogram for stages (1–3) demonstrating the split spontaneous locomotor activity rhythms in stages 1 and 2 and lack of entrainment to the 11:11 hr LDim cycles as demonstrated in stage 3 where chi-square analysis reveals a single significant dominant peak with a period of 23.9 hr. (C and G) Representative actograms for mother-reared and peer-reared individuals subjected to 11:11 hr LDim conditions for 6 wk (stages 1 and 2) during which the individual was treated first with vehicle (ethanol; stage 1) followed by melatonin during stage 2. Finally, during stage 3, melatonin was replaced by vehicle under conditions of constant dim light for 8 days. (D and H) Corresponding chi-square analysis for periodograms of stages 1–3, demonstrating two spontaneous locomotor activity rhythms in stages 1 and 2 in case of vehicle treatment and the entraining effect of melatonin treatment in stage 2 as shown by chi-square analysis. Locomotor activity rhythms with a confidence level of 99.9% were considered as statistically significant. The periods (inserts) were indicated where rhythmicity was significant. Oblique lines indicate significance (P = 0.01). Qp values above the line are statistically significant.