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Challenging the omnipotence of the suprachiasmatic timekeeper: are circadian oscillators present throughout the mammalian brain?
Author(s) -
Guilding Clare,
Piggins Hugh D.
Publication year - 2007
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2007.05581.x
Subject(s) - suprachiasmatic nucleus , neuroscience , circadian rhythm , circadian clock , light effects on circadian rhythm , biology , hypothalamus , clock , habenula , olfactory bulb , amygdala , oscillating gene , biological neural network , central nervous system
The suprachiasmatic nucleus of the hypothalamus (SCN) is the master circadian pacemaker or clock in the mammalian brain. Canonical theory holds that the output from this single, dominant clock is responsible for driving most daily rhythms in physiology and behaviour. However, important recent findings challenge this uniclock model and reveal clock‐like activities in many neural and non‐neural tissues. Thus, in addition to the SCN, a number of areas of the mammalian brain including the olfactory bulb, amygdala, lateral habenula and a variety of nuclei in the hypothalamus, express circadian rhythms in core clock gene expression, hormone output and electrical activity. This review examines the evidence for extra‐SCN circadian oscillators in the mammalian brain and highlights some of the essential properties and key differences between brain oscillators. The demonstration of neural pacemakers outside the SCN has wide‐ranging implications for models of the circadian system at a whole‐organism level.