UC San Diego

Dim light during the scotophase facilitates extreme behavioral entrainment. The thesis analyzes dim light in two separate instances: T18 entrainment and bifurcation. In the first chapter, mice were significantly more well entrained when dim light was present for at least 3 weeks or more. In its absence, full entrainment to T18 was not obtained and there were significant differences between T18 entrained mice with at least 3 weeks of dim light than those without. Additionally, mice entrained to T18 with dim light for 3 weeks displayed Type 0 strong phase resetting when released into constant conditions without dim light, indicating a more relaxed and flexible circadian system. In Chapter 2, Per2 was shown to be unimodal and rhythmic on a 24h basis.