Circadian Rhythm Resetting in Sparrows: Early Response to Doublet Light Pulses

Abstract

Circadian responses were studied using the perching activity of house sparrows (Passer domesticus). The sparrows were subjected to single or double 4-hr light pulses (the single pulses or the second pulses of the doublets scanned 24 hr) in the first cycle after previous entrainment to a light-dark cycle (LD 12:12). The differences in times at which the birds commenced perch-hopping in LD 12:12 before the pulses and in the five cycles immediately following the pulses were determined (phase shifts). A 24-hr time profile for phase shifts in response to single light pulses replicated our previous study: Early-night pulses delayed the rhythm (-1.7 hr), while late-night pulses advanced the rhythm (+3.8 hr). After pretreatment with a light pulse that advanced the birds +2.7 hr, the resetting curve was advanced. There were no delays; the range of average shifts was +0.1 hr to +6.2 hr. After pretreatment with a light pulse that delayed the birds -1.7 hr, the resetting curve was delayed. Average delays as much as -1.1 hr and advances up to +2.1 hr were measured. The data for double pulses were interpreted from predictions made from single-pulse data.

Rapid Resetting of the Mammalian Circadian Clock

“…Nevertheless, the current findings complement studies in Drosophila (Pittendrigh, 1967(Pittendrigh, , 1979 and Neurospora (S. Dharmananda thesis cited in Crosthwaite et al, 1995), showing that the oscillator was reset within 3 or 0.75 hr, respectively, although they exhibit type 0 resetting. In double-pulse experiments with sparrows (Binkley and Mosher, 1987), photic resetting was observed within 8 hr, but because 4 hr pulses were used, the time course could not be defined more precisely. In a different context examining the behavior of transient phase shifts during advances of the hamster circadian system, Elliott and Pittendrigh (1996) concluded that although f ull delays were completed within one cycle and advances of behavioral rhythm were not completed until ϳ6 d, detectable shifts of the oscillator could be observed between 2 and 4 hr after a pulse, as reported here.…”

Two Circadian Rhythms in Pairs of Sparrows

“…The methods we used for recording rhythms of sparrows and for data analysis were the same as in our prior investigations (Binkley and Mosher, 1987). We note that the recording method has limitations.…”

“…Records in which there were technical problems with the lights or recorder, or where activity was too sparse to make an evaluation, or during which a bird died, were not used; however, a few records that were shorter or longer than those obtained from the standard protocols were included in the analyses. Data analyses were made by making measurements on the sparrows' ink event recordings arrayed by the method of Richter (1965) and reduced photographically using the method employed by us previously (Binkley and Mosher, 1987).…”

Daylight and Artificial Light Phase Response Curves for the Circadian Rhythm in Locomotor Activity of the Field Mouse Mus booduga

“…The innateness (genetic control) of the oscillation characteristics of these is attested to in many ways, including its susceptibility to change of spontaneous frequency (period) by laboratory selection (Pittendrigh, 1981) or by chemical mutagenesis (Konopka and Benzer, 1971). Regardless of the fact that the first light pulse phase-resetting was reported as early as 1958 (Hastings and Sweeney, 1958) and has since been investigated in depth in several eukaryotic systems (Johnson, 1990(Johnson, , 1992Kronauer et al, 1993;Boivin et al, 1996), the subject is still intriguing, as manifested by the sustained interest in the understanding of entrainment kinetics and clock mechanisms (Dharmananda, 1980;Pittendrigh, 1981;Binkley and Mosher, 1987;Johnson, 1992;Crosthwaite et al, 1995). The biologically significant features of the entrainment phenomenon relating to the control of the circadian rhythms by periodicities in the external environment are twofold (Pittendrigh, 1965): 1.…”