Circadian Phase of Sparrows: Control by Light and Dark

Abstract

Abstract— Sparrows (Passer domesticus) are day‐active birds which exhibit circadian rhythms of perch‐hopping activity. The phases of sparrow's circadian rhythms were studied following single 4 h light pulses, single 4 h dark pulses, doublet treatments of light and dark pulses, and a 10 h light pulse. The sparrows exhibited a phase response curve to 4 h light pulses with maximum phase advances (3.8 h) at CT20 and maximum phase delays(–1.3 h) at CT16. The sparrows also displayed a phase response curve to dark pulses with maximum phase advances (2.2 h) at CT16 and maximum phase delays at CTO(–0.7 h). The remaining pulses were imposed during the subjective dark‐time. The 10 h pulse beginning 1 h after lights‐out produced a 2.2 h phase shift. The doublet of 2 h pulses that were the “skeleton” of the 10 h pulse produced a 2.5 h phase shift. The early 2 h pulse, applied by itself resulted in a ‐0.4 h delay; the late 2 h pulse applied singly produced a 3.1 h advance. When an early 3 h dark pulse was imposed together with a late light pulse, the phase was advanced 3.6 h; singly the pulses produced 1.8 h and 2.7 h advances.

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

“…The phases of the sparrows' activity onsets were little changed by this procedure ( + 0.1 hr). The result agrees with those of prior studies (Eskin, 1971;Klein et al, 1985).…”

“…1C, 2B, 2C, 3A; Table 1) replicated a previous study (Klein et al, 1985) and yielded a phase-resetting curve. The control FIGURE 1.…”

“…Maier (1973) measured phase responses for 5-min light pulses in Drosophila exposed to temperature pulses (which produced delays); the experiments showed that a temperature pulse could phase-shift the response curve. Klein et al (1985) imposed a 3-hr dark pulse together with a 3-hr bright light pulse (in dim light) during the first subjective night at times corresponding to the advancing portions of the light-pulse and dark-pulse response curves; the + 3.6-hr shift obtained was larger than either pulse produced by itself (+1.8 hr and +2.7 hr, respectively). Pittendrigh (1981) measured phase response curves for eclosion using Drosophila populations; these were first exposed to a 15-min pulse that delayed the eclosion rhythm ( -5.9 hr) or a pulse that advanced the rhythm (+6.0 hr).…”

“…We modified methodology used to study resetting in other species, where phase shifts in response to single-pulse treatments were measured at various times of the circadian cycle (Pittendrigh and Bruce, 1957;DeCoursey, 1961DeCoursey, , 1986. We imposed 4-hr light or dark pulses (during the first 24 hr of constant conditions following the last day of an LD cycle) and compared the phase of the sparrows' activity onsets (e.g., in the first 5 days of constant conditions after the cycle in which the pulse was imposed) with the phase the sparrows previously exhibited in the LD cycle (Binkley, 1985;Klein et al, 1985;Binkley and Mosher, 1986). The facts that emerged from the studies that utilized LD 12:12 as the pretreatment cycle were as follows: (1) Light pulses in the late subjective night advanced the rhythm, light pulses in the early subjective night delayed the rhythm, and light pulses had less effect on the rhythm in the subjective day; (2) dark pulses produced phase shifts that were roughly opposite in sign to those produced by light pulses; and (3) there was a point in darkness when the animals abruptly changed their resetting responses from advances to delays or delays to advances.…”

Circadian Rhythm in Pineal N‐Acetyltransferase Activity: Phase Shifting by Dark Pulses (III)

“…Some investigators have suggested that the pattern of response to dark pulses is the "mirror image" of the pattern observed for the light pulse phase response curve in the same species. However, it is clear from the available data for finch, hamster, bat, and sparrow locomotor activity (Aschoff, 1965;De-Coursey, 1973;Subbaraj and Chandrashekaran, 1981;Boulos and Rusak, 1982;Ellis et al, 1982;Klein et al, 1985) and the phase response curves shown here that the responses are opposite in direction at some but not all points. Furthermore, the light and dark pulse phase response curves are not parallel at all portions.…”