Methods Enzymol 2005 ;393:623-42
Department of Biology, Center for Biological Timing, University of Virginia, Charlottesville, Virginia 22903, USA.
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J Soc Biol 2009 10;203(1):49-63. Epub 2009 Apr 10.
Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, CNRS-UMR 6231, Université de la Méditerranée, Faculté de Médecine, secteur nord, boulevard Pierre Dramard, 13916 Marseille Cedex 20, France.
The mammalian circadian clock, whose central component is located in the suprachiasmatic nucleus of the hypothalamus (SCN), orchestrates rhythmic events in metabolism, physiology and behavior. Adaptation of the organism to its environment requires precise adjustment of the clock to the 24 h astronomical time, primarily by the light/dark cycle. Photic synchronization acts on both the molecular loops which trigger circadian oscillations and the phasing of the multiple SCN cellular oscillators whose coordination permits elaboration of the rhythmic message that will be distributed throughout the organism. Read More
Physiol Rev 2010 Jul;90(3):1063-102
Laboratory of Chronobiology, Department of Science and Technology, University of Quilmes/Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Quilmes, Argentina.
Mammalian circadian rhythms are controlled by endogenous biological oscillators, including a master clock located in the hypothalamic suprachiasmatic nuclei (SCN). Since the period of this oscillation is of approximately 24 h, to keep synchrony with the environment, circadian rhythms need to be entrained daily by means of Zeitgeber ("time giver") signals, such as the light-dark cycle. Recent advances in the neurophysiology and molecular biology of circadian rhythmicity allow a better understanding of synchronization. Read More
J Biol Rhythms 2006 Dec;21(6):470-81
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
The SCN of the mammalian hypothalamus comprises a self-sustained, biological clock that generates endogenous ca. 24-h (circadian) rhythms. Circadian rhythmicity in the SCN originates from the interaction of a defined set of "clock genes" that participate in transcription/translation feedback loops. Read More
PLoS One 2008 8;3(12):e3884. Epub 2008 Dec 8.
Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
Background: Circadian ( approximately 24 hr) rhythms are generated by the central pacemaker localized to the suprachiasmatic nucleus (SCN) of the hypothalamus. Although the basis for intrinsic rhythmicity is generally understood to rely on transcription factors encoded by "clock genes", less is known about the daily regulation of SCN neuronal activity patterns that communicate a circadian time signal to downstream behaviors and physiological systems. Action potentials in the SCN are necessary for the circadian timing of behavior, and individual SCN neurons modulate their spontaneous firing rate (SFR) over the daily cycle, suggesting that the circadian patterning of neuronal activity is necessary for normal behavioral rhythm expression. Read More