The mammalian circadian clock shop

In mammals, a master circadian pacemaker driving daily rhythms in behavior and physiology resides in the suprachiasmatic nucleus (SCN). The SCN contai ns multiple circadian oscillators that synchronize to environmental cycles and to each other in vivo. Rhythm production, an intracellular event, depen ds on more than right identified genes. The period of the rhythms within th e SCN also depends upon intercellular communication. Many other tissues als o retain the ability to generate near 24-h periodicities although their pla ce in the organization of circadian timing is still unclear. This paper foc uses on the tissue-, cellular- and molecular level events that generate and entrain circadian rhythms in behavior in mammals and emphasizes the appare nt differences between the SCN and peripheral oscillators.