Spontaneous synchronization of coupled circadian oscillators

Biophys J. 2005 Jul;89(1):120-9. doi: 10.1529/biophysj.104.058388. Epub 2005 Apr 22.


In mammals, the circadian pacemaker, which controls daily rhythms, is located in the suprachiasmatic nucleus (SCN). Circadian oscillations are generated in individual SCN neurons by a molecular regulatory network. Cells oscillate with periods ranging from 20 to 28 h, but at the tissue level, SCN neurons display significant synchrony, suggesting a robust intercellular coupling in which neurotransmitters are assumed to play a crucial role. We present a dynamical model for the coupling of a population of circadian oscillators in the SCN. The cellular oscillator, a three-variable model, describes the core negative feedback loop of the circadian clock. The coupling mechanism is incorporated through the global level of neurotransmitter concentration. Global coupling is efficient to synchronize a population of 10,000 cells. Synchronized cells can be entrained by a 24-h light-dark cycle. Simulations of the interaction between two populations representing two regions of the SCN show that the driven population can be phase-leading. Experimentally testable predictions are: 1), phases of individual cells are governed by their intrinsic periods; and 2), efficient synchronization is achieved when the average neurotransmitter concentration would dampen individual oscillators. However, due to the global neurotransmitter oscillation, cells are effectively synchronized.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Clocks
  • Circadian Rhythm / physiology*
  • Humans
  • Kinetics
  • Light
  • Models, Biological
  • Models, Statistical
  • Neurons / metabolism
  • Neurotransmitter Agents / metabolism
  • Oscillometry / methods*
  • Periodicity
  • RNA, Messenger / metabolism
  • Suprachiasmatic Nucleus / metabolism*
  • Time Factors
  • Transcription, Genetic


  • Neurotransmitter Agents
  • RNA, Messenger