Behavioral and neurochemical sources of variability of circadian period and phase: studies of circadian rhythms of npy−/− mice

2007 ◽  
Vol 292 (3) ◽  
pp. R1306-R1314 ◽  
Author(s):  
Mary Harrington ◽  
Penny Molyneux ◽  
Stephanie Soscia ◽  
Cheruba Prabakar ◽  
Judy McKinley-Brewer ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Activity Patterns ◽  
Circadian Period ◽  
Running Wheel ◽  
Clock Period ◽  
A Value ◽  
Free Running ◽  
The Mean ◽  
Delayed Phase

The cycle length or period of the free-running rhythm is a key characteristic of circadian rhythms. In this study we verify prior reports that locomotor activity patterns and running wheel access can alter the circadian period, and we report that these treatments also increase variability of the circadian period between animals. We demonstrate that the loss of a neurochemical, neuropeptide Y (NPY), abolishes these influences and reduces the interindividual variability in clock period. These behavioral and environmental influences, from daily distribution of peak locomotor activity and from access to a running wheel, both act to push the mean circadian period to a value < 24 h. Magnitude of light-induced resetting is altered as well. When photoperiod was abruptly changed from a 18:6-h light-dark cycle (LD18:6) to LD6:18, mice deficient in NPY were slower to respond to the change in photoperiod by redistribution of their activity within the prolonged dark and eventually adopted a delayed phase angle of entrainment compared with controls. These results support the hypothesis that nonphotic influences on circadian period serve a useful function when animals must respond to abruptly changing photoperiods and point to the NPYergic pathway from the intergeniculate leaflet innervating the suprachiasmatic nucleus as a circuit mediating these effects.

Circadian activity of the white sucker, Catostomus commersoni: comparison of individual and shoaling fish

1980 ◽  
Vol 58 (8) ◽  
pp. 1399-1403 ◽  
Author(s):  
Martin Kavaliers
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Social Organization ◽  
Constant Darkness ◽  
White Sucker ◽  
Circadian Period ◽  
Circadian Activity ◽  
Catostomus Commersoni ◽  
Free Running ◽  
Precise Version

Individual and shoaling white suckers, Catostomus commersoni, displayed free running circadian rhythms of locomotor activity under conditions of constant darkness and temperature. The circadian activity of shoals was different from that of single fish. The activity of single fish was rhythmic initially with a period of less than 24 h, but became arrhythmic after 15–30 days. Shoals of white suckers had a less variable circadian period that was greater than 24 h, and showed no evidence of arrhythmicity. The circadian activity of shoals is determined by its behavioural and social organization; it is not simply a more precise version of the activity of single fish.

Internal synchronization among several circadian rhythms in rats under constant light

1978 ◽  
Vol 235 (5) ◽  
pp. R243-R249 ◽  
Author(s):  
K. I. Honma ◽  
T. Hiroshige
Keyword(s):  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Continuous Light ◽  
Biological Rhythms ◽  
Plasma Corticosterone ◽  
Dark Cycle ◽  
Internal Oscillator ◽  
Free Running ◽  
Phase Angles

Three biological rhythms (locomotor activity, body temperature, and plasma corticosterone) were measured simultaneously in individual rats under light-dark cycles and continuous light. Spontaneous locomotor activity was recorded on an Animex and body temperature was telemetrically monitored throughout the experiments. Blood samples were obtained serially at 2-h intervals on the experimental days. Phase angles of these rhythms were calculated by a least-squares spectrum analysis. Under light-dark cycles, the acrophases of locomotor activity, body temperature, and plasma corticosterone were found at 0029, 0106, and 1940 h, respectively. When rats were exposed to 200 lx continuous light, locomotor activity and body temperature showed free-running rhythms with a period of 25.2 h on the average. Plasma corticosterone levels determined at 12 days after exposure to continuous light exhibited a circadian rhythm with the acrophase shifted to 0720. The acrophases of locomotor activity and body temperature, determined simultaneously on the same day, were found to be located at 1303 and 1358 h, respectively. Phase-angle differences among the three rhythms on the 12th day of continuous light were essentially the same with those under the light-dark cycle. These results suggest that circadian rhythms of locomotor activity, body temperature, and plasma corticosterone are most probably coupled to a common internal oscillator in the rat.

Relationships Between Photoperiodism and Circadian Rhythms of Activity in the House Finch

1967 ◽  
Vol 46 (1) ◽  
pp. 43-61 ◽  
Author(s):  
W. M. HAMNER ◽  
J. T. ENRIGHT
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Activity Patterns ◽  
Measuring System ◽  
Carpodacus Mexicanus ◽  
House Finch ◽  
Phase Lead ◽  
Physiological Processes ◽  
Circadian Time ◽  
Large Phase

1. The Bunning hypothesis proposes that many rhythmic physiological processes, including photoperiodic responsiveness, are all based upon a single, endogenous circadian time-measuring system (‘die physiologische Uhr’). We have attempted to test this hypothesis by examining correlations between the circadian waking-sleeping rhythm of the house finch (Carpodacus mexicanus), and the circadian rhythm of sensitivity to light, which underlies the photoperiodic testicular responses of this species. 2. Experimental techniques included (1) comparisons of locomotor activity patterns induced by specific non-daily light cycles which stimulate gametogenesis (LD 6:30 and 6:54) with those induced by other cycles which are non-inductive (LD 6:18, 6:42 and 6:66); (2) comparisons of gametogenesis resulting from light cycles which produce large phase-lead in the activity rhythms and thereby result in photic stimulation late in the ‘subjective day’ (LD 6:20 and 3:23) with results from similar cycles which cause no phase lead (LD 6:16 and 3:19); and (3) comparisons of gametogenesis under free-running (unsynchronized) conditions in which a 6 hr. stimulus was intermittently administered early in the ‘subjective day’, with other treatments in which the same stimulus was administered late in the ‘subjective day’. 3. In all experimental series, when only group responses are considered, there were clear and strong correlations between testicular growth and the patterns observed in locomotor activity. The nature of the large intra-group variability, however, convinces us that the Bünning hypothesis, as here interpreted, is inadequate to account for all the results. Either the two circadian rhythms may be independent, similar systems; or, if there is a single ‘master clock’, the two manifestations of this timing system are apparently not phase-locked under artificial laboratory conditions. It is not clear to us how these two alternatives are experimentally distinguishable.

Daily exposure to a running wheel entrains circadian rhythms in mice in parallel with development of an increase in spontaneous movement prior to running-wheel access

2013 ◽  
Vol 305 (11) ◽  
pp. R1367-R1375 ◽  
Author(s):  
Yujiro Yamanaka ◽  
Sato Honma ◽  
Ken-ichi Honma
Keyword(s):  
Circadian Rhythms ◽  
Fixed Time ◽  
Time Of Day ◽  
Constant Darkness ◽  
Spontaneous Movement ◽  
Running Wheel ◽  
Daily Exposure ◽  
Free Running ◽  
Nonphotic Entrainment ◽  
Circadian Behavior

Entrainment of circadian behavior rhythms by daily exposure to a running wheel was examined in mice under constant darkness. Spontaneous movement was individually monitored for more than 6 mo by a thermal sensor. After establishment of steady-state free running, mice were placed in a different cage equipped with a running-wheel for 3 h once per day at 6 AM. The daily exchange was continued for 80 days. The number of wheel revolutions during exposure to the running wheel was also measured simultaneously with spontaneous movement. In 13 out of 17 mice, circadian behavior rhythm was entrained by daily wheel exposure, showing a period indistinguishable from 24 h. The entrainment occurred in parallel with an increase in spontaneous movement immediately prior to the daily wheel exposure. A similar preexposure increase was observed in only one of four nonentrained mice. The preexposure increase appeared in 19.5 days on average after the start of daily wheel exposure and persisted for 36 days on average after the termination of the exposure schedule. The preexposure increase was detected only when daily wheel exposure came into the activity phase of the circadian behavior rhythm, which was accompanied by an increase in the number of wheel revolutions. These findings indicate that a novel oscillation with a circadian period is induced in mice by daily exposure to a running wheel at a fixed time of day and suggest that the oscillation is involved in the nonphotic entrainment of circadian rhythms in spontaneous movement.

Comparative locomotor activity patterns in the portunid crabs Liocarcinus holsatus and L. depurator

1991 ◽  
Vol 71 (1) ◽  
pp. 1-10 ◽  
Author(s):  
P. Abelló ◽  
D. G. Reid ◽  
E. Naylor
Keyword(s):  
Locomotor Activity ◽  
Activity Patterns ◽  
High Tide ◽  
Sandy Beaches ◽  
Maximum Activity ◽  
Circadian Activity ◽  
Activity Rhythms ◽  
Sublittoral Zone ◽  
Free Running ◽  
Behavioural Mechanism

The free-running locomotor activity rhythms of freshly-captured swimming crabs Liocarcinus holsatus and L. depurator have been studied in constant conditions in the laboratory. L. holsatus captured in the intertidal zone of sandy beaches showed strong circatidal activity rhythms with maximum activity at high tide. L. holsatus captured in the sublittoral zone had a clear tendency to show circadian activity rhythms with highest activity during day-time hours. L. depurator occurred only sublittorally and showed circadian activity patterns with highest activity during the night. Exposure to hydrostatic pressure cycles of tidal amplitude and periodicity, entrained strong circatidal activity rhythms in previously arhythmic L. holsatus. This activity pattern also showed a marked circadian component. Exposure to the same regime entrained a circadian rhythm, but not a circatidal rhythm in L. depurator. In the sublittoral zone L. depurator is active mainly during the night, whereas L. holsatus, is active mainly during the day. This may constitute a behavioural mechanism for minimizing competitive interactions between these two sympatric crabs.

scholarly journals Magnetic fluctuations affect circadian patterns of locomotor activity in zebrafish

2021 ◽  
Author(s):  
Viacheslav V. Krylov ◽  
Evgeny I. Izvekov ◽  
Vera V. Pavlova ◽  
Natalia A. Pankova ◽  
Elena A. Osipova
Keyword(s):  
Magnetic Field ◽  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Danio Rerio ◽  
Magnetic Fluctuations ◽  
Constant Illumination ◽  
Free Running ◽  
Circadian Patterns

AbstractThe locomotor activity of zebrafish (Danio rerio) has a pronounced, well-studied circadian rhythm. Under constant illumination, the period of free-running locomotor activity in this species usually becomes less than 24 hours. To evaluate the entraining capabilities of slow magnetic variations, zebrafish locomotor activity was evaluated at constant illumination and fluctuating magnetic field with a period of 26.8 hours. Lomb-Scargle periodogram revealed significant free-running rhythms of locomotor activity and related behavioral endpoints with a period close to 27 hours. Obtained results reveal the potential of slow magnetic fluctuations for entrainment of the circadian rhythms in zebrafish. The putative mechanisms responsible for the entrainment are discussed, including the possible role of cryptochromes.

Modeling the Influence of Synaptic Plasticity on After-effects

2019 ◽  
Vol 34 (6) ◽  
pp. 645-657
Author(s):  
Semra Foster ◽  
Tom Christiansen ◽  
Michael C. Antle
Keyword(s):  
Mathematical Model ◽  
Synaptic Plasticity ◽  
Circadian Rhythms ◽  
Weighted Average ◽  
Cycle Period ◽  
Circadian Period ◽  
After Effects ◽  
A Cell ◽  
Free Running ◽  
And Behavior

While circadian rhythms in physiology and behavior demonstrate remarkable day-to-day precision, they are also able to exhibit plasticity in a variety of parameters and under a variety of conditions. After-effects are one type of plasticity in which exposure to non–24-h light-dark cycles (T-cycles) will alter the animal’s free-running rhythm in subsequent constant conditions. We use a mathematical model to explore whether the concept of synaptic plasticity can explain the observation of after-effects. In this model, the SCN is composed of a set of individual oscillators randomly selected from a normally distributed population. Each cell receives input from a defined set of oscillators, and the overall period of a cell is a weighted average of its own period and that of its inputs. The influence that an input has on its target’s period is determined by the proximity of the input cell’s period to the imposed T-cycle period, such that cells with periods near T will have greater influence. Such an arrangement is able to duplicate the phenomenon of after-effects, with relatively few inputs per cell (~4-5) being required. When the variability of periods between oscillators is low, the system is quite robust and results in minimal after-effects, while systems with greater between-cell variability exhibit greater magnitude after-effects. T-cycles that produce maximal after-effects have periods within ~2.5 to 3 h of the population period. Overall, this model demonstrates that synaptic plasticity in the SCN network could contribute to plasticity of the circadian period.

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