Body Clocks Outside the Main Brain Timer Influenced by Methamphetamine and Food Restriction

The central catecholaminergic system is probably involved in the expression of SCN-independent rhythms.

• Mammals have a central clock in the hypothalamic suprachiasmatic nucleus (SCN) and peripheral clocks in various tissues.
• Two SCN-independent clocks respond to nonphotic cues: one induced by methamphetamine and another by restricted feeding.
• SCN-independent rhythms do not require canonical clock genes for expression.
• Unique phenomena such as spontaneous internal desynchronization and nonphotic entrainment are observed in MAP-induced activity rhythms in rats and human sleep-wake cycles.
• The SCN-independent clock may regulate behavior in response to nonphotic time cues and is related to arousal mechanisms.

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