title: The microarchitecture of C. elegans behavior during lethargus: homeostatic bout dynamics, a typical body posture, and regulation by a central neuron.
abstract: OBJECTIVE
  The nematode C. elegans develops through four larval stages before it reaches adulthood. At the transition between stages and before it sheds its cuticle, it exhibits a sleep-like behavior during a stage termed lethargus. The objectives of this study were to characterize in detail behavioral patterns and physiological activity of a command interneuron during lethargus.
  
  
  RESULTS
  We found that lethargus behavior was composed of bouts of quiescence and motion. The duration of individual bouts ranged from 2 to 100 seconds, and their dynamics exhibited local homeostasis: the duration of bouts of quiescence positively correlated with the duration of bouts of motion that immediately preceded them in a cAMP-dependent manner. In addition, we identified a characteristic body posture during lethargus: the average curvature along the body of L4 lethargus larvae was lower than that of L4 larvae prior to lethargus, and the positions of body bends were distributed non-uniformly along the bodies of quiescent animals. Finally, we found that the AVA interneurons, a pair of backward command neurons, mediated locomotion patterns during L4 lethargus in similar fashion to their function in L4 larvae prior to lethargus. Interestingly, in both developmental stages backward locomotion was initiated and terminated asymmetrically with respect to AVA intraneuronal calcium concentration.
  
  
  CONCLUSIONS
  The complex behavioral patterns during lethargus can be dissected to quantifiable elements, which exhibit rich temporal dynamics and are actively regulated by the nervous system. Our findings support the identification of lethargus as a sleep-like state.
  
  
  BACKGROUND
  Iwanir S; Tramm N; Nagy S; Wright C; Ish D; Biron D. The microarchitecture of C. elegans behavior during lethargus: homeostatic bout dynamics, a typical body posture, and regulation by a central neuron. SLEEP 2013;36(3):385-395.
authors: Department of Physics, James Franck Institute, University of Chicago, Chicago, IL 60637, USA.
authors: Shachar
authors: S
authors: Iwanir
authors: Nora
authors: N
authors: Tramm
authors: Stanislav
authors: S
authors: Nagy
authors: Charles
authors: C
authors: Wright
authors: Daniel
authors: D
authors: Ish
authors: David
authors: D
authors: Biron
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000254:growth & development / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D007395:Interneurons; D007814:Larva / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D015398:Signal Transduction; D012890:Sleep / Q000502:physiology*
keywords: Behavior; C. elegans; homeostasis; lethargus