Freerunning and Entrained Circadian Rhythms

Aschoff, Jürgen

doi:10.1007/978-1-4615-6552-9_6

Cited by 190 publications

(187 citation statements)

References 28 publications

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“…In a natural environment, the daily light.dark cycle provides a fairly stable reference for animals. Many laboratory studies have confirmed that this seems to be an extremely salient timing cue (see Aschoff, 1981). Following from this, in Experiment 4 the light:dark cycle was manipulated with an advance of the time of lights on.…”

Section: Extension Of Paradigmmentioning

confidence: 84%

Time-of-day discrimination by pigeons,Columba livia

Saksida

Wilkie

1994

Animal Learning & Behavior

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Pigeons were trained to discriminate between four keys. One provided food in the mornings, another provided food in the afternoons, and two never provided food. Three experiments were performed to determine whether pigeons could track food availability over a 24-h period. All the subjects appeared to demonstrate time-place associative learning. A fourth experiment was designed to investigate the mechanisms underlying the timing behavior. Lights-on time was shifted back by 6 h, and no decrease in performance was found during the first session following the phase shift. This suggests that a circadian type oftiming mechanism with a self-sustaining oscillator mediates time-place learning over a period of 24 h. Further support for this notion was found in a fifth experiment, in which the subjects were tested in constant dim light. In that experiment, the subjects' continued correct responding provides additional support for a selfsustaining circadian timer.

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Section: Extension Of Paradigmmentioning

confidence: 84%

Time-of-day discrimination by pigeons,Columba livia

Saksida

Wilkie

1994

Animal Learning & Behavior

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“…Considering that the free-running period of mice is 23.6 h on average, a maximal daily phase delay of 0.4 h would prevent entrainment to LD 12:12 for all mice with circadian periods shorter than average. Yet, all mice can entrain to LD 12:12, and many can entrain to LD cycles with periods up to 28 h [2]. A normal LD cycle contains more than just 1 h of light per day, but how the additional light contained in an LD cycle produces the full shift required for entrainment in non-dark-adapted mice (and other species) remains to be elucidated.…”

Section: Discussionmentioning

confidence: 99%

Enhanced circadian photoresponsiveness after prolonged dark adaptation in seven species of diurnal and nocturnal rodents

Refinetti

2007

Physiology & Behavior

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Previous studies in mice and Syrian hamsters have described an enhancement of circadian photoresponsiveness after exposure to darkness for several weeks. The present study investigated the generality of the phenomenon in 3 diurnal and 4 nocturnal rodent species. In four of the species tested, phase delays of the running-wheel activity rhythm evoked by 1-h light pulses were severalfold larger after 3 to 4 weeks of exposure to darkness than after a single day. This drastic change in photoresponsiveness has important implications for the understanding of the process of photic entrainment. Differences between species that showed a significant effect of dark adaptation and species that showed no effect were not accounted for by temporal niche (diurnal versus nocturnal) or photic sensitivity (albino versus pigmented). Further research is needed to elucidate the mechanisms responsible for inter-species differences in the occurrence of enhanced photoresponsiveness after dark adaptation and to identify the neural substrates of this phenomenon in species that exhibit it.

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“…In the absence of external cues, circadian rhythms free-run with an intrinsic period close to that of the environmental period. The inherent period of a circadian rhythm is usually species specific, although intra-specific variation may be present (Pittendrigh & Daan 1974;Aschoff 1981;Refinetti 2006). …”

Section: Introductionmentioning

confidence: 99%

Now you see me, now you don’t: The locomotory activity rhythm of the Asian garden dormouse (Eliomys melanurus) from Saudi Arabia

Alagaili¹,

Mohammed²,

Bennett³

et al. 2014

Mammalian Biology

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The circadian rhythm of locomotory activity in the Asian garden dormouse, Eliomys melanurus from Saudi Arabia was investigated under controlled laboratory conditions. Eleven individuals were subjected to successive light cycles of two weeks. Locomotory activity of the dormouse was confined mainly to the dark phases of the LD and DL cycles.On the LD cycle, the mean percentage of activity was 95.5 ± 0.9% during the dark phase.When subjected to constant darkness all animals expressed free running rhythms of locomotor activity (mean 24h06 ± 0h09). Upon inversion of the LD cycle, activity reentrained to the new light cycle within 3 days and a percentage of nocturnal activity of 96.8 ± 0.7%. When the dark component of the day was lengthened to 8L:16D the active time increased significantly from 11h43 ± 0h05 to 13h43 ± 0h22. In contrast, when the dark component was shortened 16L: 8D the active time decreased significantly from that of the 12L:12D to 7h58 ± 0h04. There was no difference in the locomotor activity at 20 and 30 o C however, dormice entered torpor at 10 o C,being almost completely inactive.The Asian garden dormouse possesses a circadian rhythm of locomotor activity that entrains strongly to light. The rhythm of locomotor activity occurs predominantly during the dark phase and thus this species can be considered truly nocturnal in habit.

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Freerunning and Entrained Circadian Rhythms

Cited by 190 publications

References 28 publications

Time-of-day discrimination by pigeons,Columba livia

Time-of-day discrimination by pigeons,Columba livia

Enhanced circadian photoresponsiveness after prolonged dark adaptation in seven species of diurnal and nocturnal rodents

Now you see me, now you don’t: The locomotory activity rhythm of the Asian garden dormouse (Eliomys melanurus) from Saudi Arabia

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