title: Contribution of norepinephrine to emotional memory consolidation during sleep.
abstract: BACKGROUND
  There is increasing evidence indicating that slow wave sleep (SWS) supports memory consolidation. This effect may in part originate from phasic noradrinergic (NE) activity occurring during SWS in the presence of tonically lowered NE levels. Here, we examined whether NE supports the consolidation of amygdala-dependent emotional memory during SWS.
  
  
  METHODS
  In a double-blind cross-over study, 15 men learned emotional and neutral materials (stories, pictures) in the evening before a 3-h period of early SWS-rich retention sleep, during which either placebo or clonidine, an α2-adrenoceptor agonist which blocks locus coeruleus NE release, was intravenously infused. Memory retrieval as well as affective ratings and heart rate responses to the pictures were assessed 23 h after learning.
  
  
  RESULTS
  Clonidine reduced plasma NE levels but had no effect on SWS. While retention of story content words and pictures per se remained unaffected, clonidine distinctly blocked the superiority of emotional compared to neutral memory for temporal order, with this superiority of emotional over neutral memories observed only in the placebo condition. Heart rate responses to pictures were not affected, but whereas under placebo conditions familiar negative pictures were rated less arousing and with a more negative valence compared to pictures not seen before; these differences were abolished after clonidine.
  
  
  CONCLUSIONS
  Given that memory for the temporal order of events depends on the hippocampus to a greater extent than item memory, our findings suggest that NE activity during early SWS-rich sleep facilitates consolidation of memories that involve both, a strong amygdalar and hippocampal component.
authors.affiliation: Department of Neuroendocrinology, University of Luebeck, Haus 50.1, Ratzeburger Allee 160, 23538 Luebeck, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Groch
authors.forename: Ines
authors.initials: I
authors.lastname: Wilhelm
authors.forename: Susanne
authors.initials: S
authors.lastname: Diekelmann
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Sayk
authors.forename: Steffen
authors.initials: S
authors.lastname: Gais
authors.forename: Jan
authors.initials: J
authors.lastname: Born
mesh_terms: D000328:Adult; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004644:Emotions / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology / Q000502:physiology*; D010919:Placebos; D012153:Retention, Psychology / Q000187:drug effects / Q000502:physiology*; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology; D055815:Young Adult
chemical_list: D010919:Placebos; D009638:Norepinephrine