Simulations of Free-running Rhythms, Light Entrainment and the Light-pulse Phase Response Curves for the Locomotor Activity Rhythm inperiodMutant ofDrosophila melanogaster

Female rats exposed to low intensities (0.1–1.5 lx) of continuous light (LL), displayed regular estrous cycles and free-running circadian rhythms of locomotor activity. In most rats, as the intensity of LL was increased to >2.0 lx, components within the active portion (α) of the locomotor rhythm remained synchronized as the periodicity of the rhythm lengthened. However, in a few rats agr split into two components; one of which free-ran with a period shorter than 24 h, while the other free-ran with a period longer than 24 h. As soon as the two components became maximally separated they spontaneously rejoined. In most rats, estrous cycles ceased shortly after the intensity of LL was increased to >2.0 lx even though the locomotor activity rhythm retained its unsplit free-running nature. These observations suggest that the multiple oscillators that control the rhythms of locomotor activity and the estrous cycle are normally coupled to one another. In certain intensities of LL, these oscillators uncouple and free-run with different periodicities, a condition which causes estrous cycles to cease and sometimes produces a split locomotor activity rhythm. circadian rhythm; oscillators; estrous cycle Submitted on November 9, 1981 Accepted on October 11, 1982

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Entrainment of the Larval Locomotor Activity Rhythm of a Carabid Beetle, Carabus insulicola insulicola (Coleoptera: Carabidae) to T21 and T24 Cycles and After-Effects on Free-Running Period.

Japanese Journal of Applied Entomology and Zoology ◽

10.1303/jjaez.36.169 ◽

1992 ◽

Vol 36 (3) ◽

pp. 169-175

Author(s):

Shin YAMAZAKI

Keyword(s):

Locomotor Activity ◽

Activity Rhythm ◽

Carabid Beetle ◽

After Effects ◽

Locomotor Activity Rhythm ◽

Free Running ◽

Free Running Period

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Environmental factors influencing the free-running period of locomotor activity rhythm in blinded rats

Neuroscience Research Supplements ◽

10.1016/0921-8696(87)90281-7 ◽

1987 ◽

Vol 5 ◽

pp. S134

Author(s):

Kiyohisa Takahashi ◽

Mizuo Takashima ◽

Ken Ohi ◽

Naoto Yamada ◽

Kazutaka Shimoda

Keyword(s):

Locomotor Activity ◽

Environmental Factors ◽

Activity Rhythm ◽

Locomotor Activity Rhythm ◽

Factors Influencing ◽

Free Running ◽

Free Running Period

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CIRCADIAN LOCOMOTOR ACTIVITY AND ITS ENTRAINMENT BY FOOD IN THE CRAYFISH PROCAMBARUS CLARKI

Journal of Experimental Biology ◽

10.1242/jeb.190.1.9 ◽

1994 ◽

Vol 190 (1) ◽

pp. 9-21 ◽

Cited By ~ 1

Author(s):

F F De Miguel ◽

H Aréchiga

Keyword(s):

Locomotor Activity ◽

Activity Rhythm ◽

Food Reinforcement ◽

Continuous Light ◽

Food Delivery ◽

Continuous Darkness ◽

Locomotor Activity Rhythm ◽

Activity Peak ◽

Free Running ◽

Two Peaks

The aim of our experiments has been to study the effect of light and food in the locomotor activity rhythm of the crayfish Procambarus clarki. Experiments were carried out under light:dark (LD) cycles of 12 h:12 h, under continuous darkness (DD) and under continuous light (LL). Under LD cycles, two peaks of activity were observed during the night phase of the cycle, while resting was characteristic of the day phase. Under DD or LL, it was possible to follow a free-running rhythm with a periodicity of 22.3±0.84 h in DD and 24.8±0.27 h in LL, typical of circadian rhythms of nocturnal species. A single delivery of food in the day phase of the LD cycle resulted in an outburst of locomotor activity that lasted for several hours. In the ensuing days, an activity peak appeared in phase with the time of food delivery. The food-related activity peak could be followed for up to 2 weeks without food reinforcement. Under DD and LL, food induced an activity rhythm in previously arrhythmic animals. Here the period was longer than 24 h in DD (26.2±0.12 h) and shorter in LL (22.5±0.46 h). Together, these results strongly suggest that light and food may play a role entraining a locomotor activity rhythm in crayfish.

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