1991 Volume 28 Issue 2 Pages 57-65
In rats, circadian rhythms in locomotor activity are regulated by a pacemaker (s) in the suprachiasmatic nucleus (SCN) which entrains to light-dark cycles. However, locomotor rhythms in the circadian domain appear under restricted daily feeding or chronic treatment with methamphetamine in rats with bilateral SCN lesions. These SCN-independent circadian rhythms do not entrain to light-dark cycle but to restricted daily feeding or periodic forced activity, and interact with the SCN-dependent circadian rhythm with predictable manners from the oscillation theory. On the other hand, the circadian system in human is unique for its multioscillator characteristics. The circadian rhythm in deep body temperature has common properties to the SCN-dependent circadian rhythm in rats, while properties of the circadian rhythm in sleep and wakefulness are different from the SCN-dependent circadian rhythm in many aspects, but rather similar to the SCN-independent rhythm, especially to the methamphetamine-induced rhythm. The interaction between the SCN-dependent and -independent circadian rhythms in rats is a good animal model for the human circadian system.
