Synthesis

Abstract

In many respects, circadian rhythmicity can be understood as being controlled by only one single oscillator or pacemaker. This is true as long as the different overt rhythms run synchronized internally. The properties of this type of single basic oscillator can be evaluated when the circadian system is operating under conditions experimentally manipulated. In evaluating results of those experiments, it must be differentiated between properties of the overt rhythm, which can be measured, and properties of the hypothetical basic oscillator, or pacemaker, which controls the rhythm. The properties of the overt rhythms, of course, depend on the features of the underlying oscillator, but they also depend on the features of the coupling between the oscillator and the overt rhythm, which also may be affected by the experimental conditions. Finally, the measured variable itself may have features influencing its rhythmicity (e.g., inertia).