title: Central insulin administration improves odor-cued reactivation of spatial memory in young men.
abstract: BACKGROUND
  Insulin receptors are ubiquitously found in the human brain, comprising the olfactory bulb, essential for odor processing, and the hippocampus, important for spatial memory processing.
  
  
  OBJECTIVE
  The present study aimed at examining if intranasal insulin, which is known to transiently increase brain insulin levels in humans, would improve odor-cued reactivation of spatial memory in young men.
  
  
  METHODS
  We applied a double-blind, placebo-controlled, counterbalanced within-subject design.
  
  
  METHODS
  The study was conducted at the research unit of a university hospital. Interventions/Participants/Main Outcome Measures: Following intranasal administration of either insulin (40 I.U.) or placebo, male subjects (n = 18) were exposed to eight odors. During each odor exposure, a green-colored field was presented on a 17-in. computer screen. During immediate recall (comprising 3 runs), the participants were re-exposed to each odor cue, and were asked to select the corresponding field (with visual feedback after each response). The delayed recall was scheduled ∼10 min later (without feedback). To test if insulin's putative effect on odor-place memory would be domain-specific, participants also performed a separate place and odor recognition task.
  
  
  RESULTS
  Intranasal insulin improved the delayed but not immediate odor-cued recall of spatial memory. This effect was independent of odor type and in the absence of systemic side effects (eg, fasting plasma glucose levels remained unaltered). Place and odor recognition were unaffected by the insulin treatment.
  
  
  CONCLUSIONS
  These findings suggest that acute intranasal insulin improves odor-cued reactivation of spatial memory in young men.
authors.affiliation: Diagnostic and Interventional Neuroradiology (Y.F.B., A.K., J.F.), Uniklinik RWTH Aachen, 52074 Aachen, Germany; Department of Neuroscience (C.B.), Uppsala University, 75124 Uppsala, Sweden.
authors.forename: Yvonne F
authors.initials: YF
authors.lastname: Brünner
authors.forename: Anja
authors.initials: A
authors.lastname: Kofoet
authors.forename: Christian
authors.initials: C
authors.lastname: Benedict
authors.forename: Jessica
authors.initials: J
authors.lastname: Freiherr
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D003463:Cues; D004311:Double-Blind Method; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D011939:Mental Recall / Q000187:drug effects*; D009812:Odorants; D010775:Photic Stimulation; D012903:Smell / Q000187:drug effects*; D065852:Spatial Memory / Q000187:drug effects*; D055815:Young Adult
chemical_list: D007328:Insulin