Colliding of activity onset and offset: evidence for multiple circadian oscillators
When hamsters,Mesocricetus auratus, are kept in dim light, wheel running at the onset and the offset of their active phase have different circadian periods. As a result, the active phase expands and eventually the two activity components collide. There is then a temporary explosion of activity at a time that was previously in the rest period. This is followed by disorganization of the rhythm or by phase jumps. Such phase jumps probably stem from the interaction of two oscillators with different natural periods rather than from threshold changes for the expression of activity.
KeywordsActivity Component Active Phase Rest Period Natural Period Phase Expand
Unable to display preview. Download preview PDF.
- Brainard GC, Richardson BA, King TS, Mathews SA, Reiter RJ (1983) The suppression of pineal melatonin content and N-acetyltransferase activity by different light irradiances in. the Syrian hamster: a dose-response relationship. Endocrinology 113:293–296Google Scholar
- Clopton JR (1984) Mosquito circadian and circa-bi-dian flight rhythms: a two oscillator model. J Comp Physiol A 155:1–12Google Scholar
- Hoffmann K (1971) Splitting of the circadian rhythm as a function of light intensity. In: Menaker M (ed) Biochronometry. Natl Acad Sci, Washington DC, pp 134–148Google Scholar
- Morin LP, Cummings LA (1981) Effect of surgical or photoperiodic castration, testosterone replacement or pinealectomy on male hamster running rhythmicity. Physiol Behav 26:825–838Google Scholar
- Pittendrigh CS, Daan S (1976) A functional analysis of circadian pacemakers in nocturnal rodents. V. Pacemaker structure: a clock for all seasons. J Comp Physiol 106:333–355Google Scholar
- Schwartz WJ, Gainer H (1977) Suprachiasmatic nucleus: Use of14C-labeled deoxyglucose uptake as a functional marker. Science 197:1089–1091Google Scholar
- Underwood H (1977) Circadian organization in lizards: the role of the pineal organ. Science 195:587–589Google Scholar
- Wehr TA, Goodwin FK (1981) Biological rhythms and psychiatry. In: Arieti S, Brodie HKH (eds) American handbook of psychiatry, vol 7. Basic Books, New York, pp 46–74Google Scholar
- Wirz-Justice A, Campbell IC (1982) Antidepressant drugs can slow or dissociate circadian rhythms. Experientia 38:1301–1309Google Scholar
- Zulley J, Campbell SS (1985) Napping behavior during spontaneous internal desynchronization: sleep remains in synchrony with body temperature. Human Neurobiol 4:123–126Google Scholar