Challenging the omnipotence of the suprachiasmatic timekeeper: are circadian oscillators present throughout the mammalian brain?

Evidence suggests that multiple brain regions, including the olfactory bulb and amygdala, exhibit circadian rhythms in clock gene expression and activity.

• The suprachiasmatic nucleus (SCN) has traditionally been viewed as the sole circadian pacemaker in mammals.
• Recent findings indicate that other brain areas also display clock-like activities.
• Regions such as the olfactory bulb, amygdala, and various hypothalamic nuclei show circadian rhythms in hormone output and electrical activity.
• These findings challenge the uniclock model of circadian regulation.
• The presence of additional neural pacemakers may alter our understanding of circadian systems at the organism level.

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