The search for rhythmicity in biological time-series

Enright, J. T.

doi:10.1016/0022-5193(65)90021-4

Cited by 329 publications

(96 citation statements)

References 30 publications

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“…A periodogram analysis (Schuster 1898, explained in Enright 1965) was performed by plotting amplitude, A,, vs period, p, from data on the proportion of unmetamoi-phosed settlers. Root mean square A, was obtained as in Enright (1965):…”

Section: Processes Influencing Settlement Ratementioning

confidence: 99%

Spatial and temporal patterns in barnacle settlement rate along a southern California rocky shore

Pineda¹

1994

Mar. Ecol. Prog. Ser.

127

106

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Barnacle settlement was monitored at 5 sites separated by 50 to 250 m a t Dike Rock, La Jolla, California, USA. Chthamalus spp. and Pollicipes polymerus settlement were spatially correlated at those sites. Within sites, settlement of the 2 species were correlated These results support the hypothesis of common onshore larval transport events for all sites and both species. Other spatiotemporal patterns were contrasting: 1 peak accounted for most of P polymerus settlement, while there were 5 peaks of similar magnitude for Chthamalus spp. At 2 sites, settlement plates were installed at 2 heights in the intertidal; Chthamalus spp. settlement was similar at the 2 heights, while P polyn~erus settlement was relatively different at the sites. Such spatial patterns may have resulted from a stronger behavioral component affecting settlement in P polymerus. These results suggest that, at scales of 100 m, temporal variability in settlement rate may be related to larval pool and physical transport processes, while spatial vanabllity may be associated with behavioral response and substrate availability. Chthamalus spp. settlement was hlgher at sites where rocks were surrounded by unsuitable sandy substrate, possibly because settlement on available substrate is intensified where total suitable settlement area is relatively scarce To test this, plates were installed at another site where suitable substrate was also scarce, as predicted, settlement was higher at both sites. At another study slte in Medio Camino, Mexico, settlement became more predictable anlong sites along the rocky shore after the shoreline had been partially inundated by sand, further supporting this hypothesis. The proportion of unmetamorphosed settlers of Chthamalus spp., relative to total settlement, appeared to peak on particular days of the lunar cycle and was spatially correlated at the 5 sites. The periodicity of the peaks was close to the 14.75 d spnng-to-neap cycle, suggesting that these peaks may be related to periodic shortimmersion hmes that did not allow the attached cypnds to metamorphose. Mortality of recently metamorphosed ( 5 l d ) Chthamalus spp. spat by physical damage was spatially vanable.

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Section: Processes Influencing Settlement Ratementioning

confidence: 99%

Spatial and temporal patterns in barnacle settlement rate along a southern California rocky shore

Pineda¹

1994

Mar. Ecol. Prog. Ser.

127

106

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“…Periods r of the free-running circadian rhythm were estimated using the i periodogram (9,40). Harmonic spectral analysis (14,31) was used to verify the presence of characteristic frequencies in the data.…”

Section: Hafen and Wollnikmentioning

confidence: 99%

Effect of lithium carbonate on activity level and circadian period in different strains of rats

Hafen

Wollnik

1994

Pharmacology Biochemistry and Behavior

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HAFEN, T. AND F. WOLLNIK. Effect of lithium carbonate on activity level and circadian period in different strains of rats. PHARMACOL BIOCHEM BEHAV 49(4) [975][976][977][978][979][980][981][982][983] 1994.-Lithium, an important pharmacological agent for the treatment of manic-depressive illness in humans, is known to lengthen the circadian period in a number of different species. Recent experiments, on the other hand, suggest that pharmacological agents may affect the circadian system indirectly through an increase or decrease of activity. To explore the interaction between pharmacological and activity effects on the circadian system, lithium was administered chronically to three different strains of rats (ACI, BH, and LEW) while wheel-running activity was studied quantitatively. Two of these inbred strains (BH and LEW) show profound abnormalities in their circadian activity rhythms, namely, a reduced overall level of activity and bimodal or multimodal activity patterns. Wheel-running activity was monitored for 4 weeks under baseline conditions, followed by 3 weeks with lithium treatment (0.3% Li 2 C0 1 administered with food) and 4 weeks with normal food. Treatment with lithium (average intake per day = 3.6 ± 0.2 mg) consistently decreased both the overall level and the circadian amplitude of the activity rhythm. The free-running period r was slightly lengthened during lithium treatment, while the most dramatic effect on period was observed after lithium withdrawal. Correlation analysis, however, revealed only a small negative correlation between activity level and period length, which proved significant only for animals of the ACI strain. Our data support the traditional interpretation that lithium lengthens circadian period by a direct pharmacological effect on the circadian pacemaker rather than through indirect effects of activity feedback. to the effect that the therapeutic effect of these drugs may be based on their phase delaying effect on the circadian pacemaker. So far, the mechanisms responsible for lithium's chronopharmacological actions are not known. It has been suggested that lithium could lengthen the circadian period by a) slowing of cellular oscillators, b) by altering the coupling between multiple circadian oscillators, or c) by altering light sensitivity (17). The hypothesis that lithium may weaken the mutual interaction between multiple oscillators is especially intriguing because modifications in coupling strength could theoretically account for changes in period, as well as entrained phase, wave form, and amplitude of circadian rhythms. Circadian rhythmsThe period-lengthening effect of lithium is of special interest with respect to the hypothesis that there may be an association between the pathophysiology of affective disorders and disturbances of circadian rhythms (22,48). Several studies in humans have demonstrated that many circadian rhythms are phase advanced in depressed patients compared to controls [reviewed in (12,44,45)]. Because lithium and a few other antidepressant agents (5,47...

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“…A broad description of several deficiencies of the procedure. particularly when certain kinds of non-stationarity are present, was given by Enright [ 16). Other calibrations of the periodogram, using several different types of biological rhythm data, have been undertaken 17.45) as well as comparisons of the periodogram with the autocorrelation function and the power spectrum [6].…”

Section: Apparatus and Data Analysismentioning

confidence: 99%

Effects of adult or perinatal hormonal environment on ultradian rhythms in locomotor activity of laboratory LEW/Ztm rats

Wollnik

Döhler

1986

Physiology & Behavior

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. Effects of adult or perinatal hormonal environment on ultradian rhythms in locomotor activity of laboratory LEWIZtm rats. PHYSIOL BEHA V 38(2) [229][230][231][232][233][234][235][236][237][238][239][240] 1986.-Four experiments were performed with male and female rats of the inbred strain LEW/Ztm maintained under a light-dark schedule of 12: 12 hours. The animals were subject to castration CGOX) or ovariectomy (OVX), estradiol 17J3-implantation (E2-capsules), and perinatal hormonal treatments with testosterone propionate (TP) aod an androgen antagonist (cyproterone acetate, CA). Results indicated a difference in the locomotor activity pattern between the two sexes as a result of the endogenous estradiol levels of the adult animals. The activity pall ern of male LEW rats was characterized by ultradian rhythms of 4 and 4.8 hr periods. The female LEW rats, on the other hand, generally exhibited a clear circadian activity pattern and no uttradian activity rhythms. Following ovariectomy, each of the females showed distinct ultradian rhythms. These disappeared after E2-implantation. Castration of adult males had no effect on the ultradian activity pattern. Implantation of E2-capsules resulted in a marked decrease of the ultradian activity components. Perinatal treatment of the males with an androgen antagonist (CA) did not appear to effect ultradian rhythms during adulthood. Females treated perinatally with testosterone showed a significant increase in the ultradian activity components. This effect is assumed to be due to low estrogen levels in these animals during adulthood. Our study supports the assumption that ultradian rhythms are a result of changes in I he phase relationships between several circadian oscillators. The synchrony of these oscillations seems to be facilitated by estradiol. Ultradian rhythmsLocomotor activity Gonadectomy Brain differentiation Laboratory rat SEVERAL weU-known phenomena of circadian rhythms in mammals can be explained by the model of the circadian system as a composite of multiple, highly ordered oscillators [40][41][42]46]located in or close to the suprachiasmatic nuclei in the hypothalamus [47]. The origin of similar temporal variations on a smaUer time scale, caUed ultradian or short-term rhythms, remains unclear [11]. Ultradian rhythms in locomotor activity are known to exist in laboratory rats [8, 9, 2~30, 49], however, attracting much less attention than circadian rhythms.A recent study of LEW/Ztm rats has shown that ultradian rhythms of 4 and 4.8 hr periods are geneticaUy fixed in this Estradiol Testosterone inbred strain (9]. The persistence of these ultradian rhythms foUowing the disruption of circadian organization under continuous light supported the assumption that the activity rhythms of this strain are caused by an independent ultradian oscillator [9]. Alternatively, the persistence of ultradian rhythms can be explained by changes in the phase relationships between several circadian oscillators [46). The ultradian rhythms of the inbred strain LEW/Ztm are sex-specific, ...

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The search for rhythmicity in biological time-series

Cited by 329 publications

References 30 publications

Spatial and temporal patterns in barnacle settlement rate along a southern California rocky shore

Spatial and temporal patterns in barnacle settlement rate along a southern California rocky shore

Effect of lithium carbonate on activity level and circadian period in different strains of rats

Effects of adult or perinatal hormonal environment on ultradian rhythms in locomotor activity of laboratory LEW/Ztm rats

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