title: Circadian modulation of consolidated memory retrieval following sleep deprivation in Drosophila.
abstract: OBJECTIVE
  Several lines of evidence indicate that sleep plays a critical role in learning and memory. The aim of this study was to evaluate anesthesia resistant memory following sleep deprivation in Drosophila.
  
  
  METHODS
  Four to 16 h after aversive olfactory training, flies were sleep deprived for 4 h. Memory was assessed 24 h after training. Training, sleep deprivation, and memory tests were performed at different times during the day to evaluate the importance of the time of day for memory formation. The role of circadian rhythms was further evaluated using circadian clock mutants.
  
  
  RESULTS
  Memory was disrupted when flies were exposed to 4 h of sleep deprivation during the consolidation phase. Interestingly, normal memory was observed following sleep deprivation when the memory test was performed during the 2 h preceding lights-off, a period characterized by maximum wake in flies. We also show that anesthesia resistant memory was less sensitive to sleep deprivation in flies with disrupted circadian rhythms.
  
  
  CONCLUSIONS
  Our results indicate that anesthesia resistant memory, a consolidated memory less costly than long-term memory, is sensitive to sleep deprivation. In addition, we provide evidence that circadian factors influence memory vulnerability to sleep deprivation and memory retrieval. Taken together, the data show that memories weakened by sleep deprivation can be retrieved if the animals are tested at the optimal circadian time.
authors.affiliation: Genes and Dynamics of Memory Systems, Neurobiology Unit, CNRS, ESPCI, Paris, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Le Glou
authors.forename: Laurent
authors.initials: L
authors.lastname: Seugnet
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Shaw
authors.forename: Thomas
authors.initials: T
authors.lastname: Preat
authors.forename: Valérie
authors.initials: V
authors.lastname: Goguel
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology; D005260:Female; D008568:Memory / Q000502:physiology*; D009154:Mutation / Q000235:genetics / Q000502:physiology; D012892:Sleep Deprivation / Q000503:physiopathology*