Neural circuits underlying circadian behavior in Drosophila melanogaster

Behav Processes. 2006 Feb 28;71(2-3):211-25. doi: 10.1016/j.beproc.2005.12.008. Epub 2006 Jan 18.


Circadian clocks include control systems for organizing daily behavior. Such a system consists of a time-keeping mechanism (the clock or pacemaker), input pathways for entraining the clock, and output pathways for producing overt rhythms in behavior and physiology. In Drosophila melanogaster, as in mammals, neural circuits play vital roles in all three functional subdivisions of the circadian system. Regarding the pacemaker, multiple clock neurons, each with cell-autonomous pacemaker capability, are coupled to each other in a network. The outputs of different sets of clock neurons in this network combine to produce the normal bimodal pattern of locomotor activity observed in Drosophila. Regarding input, multiple sensory modalities (including light, temperature, and pheromones) use their own circuitry to entrain the clock. Regarding output, distinct circuits are likely involved for controlling the timing of eclosion and for generating the locomotor activity rhythms. This review summarizes work on all of these circadian circuits, and discusses the broader utility of studying the fly's circadian system.

Publication types

  • Review

MeSH terms

  • Animals
  • Behavior, Animal / physiology*
  • Behavior, Animal / radiation effects
  • Biological Clocks / physiology*
  • Biological Clocks / radiation effects
  • Circadian Rhythm / physiology*
  • Circadian Rhythm / radiation effects
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / physiology*
  • Drosophila melanogaster / radiation effects
  • Light
  • Motor Activity / physiology
  • Motor Activity / radiation effects
  • Neural Pathways / cytology
  • Neural Pathways / physiology*
  • Neural Pathways / radiation effects
  • Neurons / physiology
  • Neurons / radiation effects