title: The insulin-mediated modulation of visually evoked magnetic fields is reduced in obese subjects.
abstract: BACKGROUND
  Insulin is an anorexigenic hormone that contributes to the termination of food intake in the postprandial state. An alteration in insulin action in the brain, named "cerebral insulin resistance", is responsible for overeating and the development of obesity.
  
  
  RESULTS
  To analyze the direct effect of insulin on food-related neuronal activity we tested 10 lean and 10 obese subjects. We conducted a magnetencephalography study during a visual working memory task in both the basal state and after applying insulin or placebo spray intranasally to bypass the blood brain barrier. Food and non-food pictures were presented and subjects had to determine whether or not two consecutive pictures belonged to the same category. Intranasal insulin displayed no effect on blood glucose, insulin or C-peptide concentrations in the periphery; however, it led to an increase in the components of evoked fields related to identification and categorization of pictures (at around 170 ms post stimuli in the visual ventral stream) in lean subjects when food pictures were presented. In contrast, insulin did not modulate food-related brain activity in obese subjects.
  
  
  CONCLUSIONS
  We demonstrated that intranasal insulin increases the cerebral processing of food pictures in lean whereas this was absent in obese subjects. This study further substantiates the presence of a "cerebral insulin resistance" in obese subjects and might be relevant in the pathogenesis of obesity.
authors: Internal Medicine IV, Department of Endocrinology and Diabetes, Angiology, Nephrology and Clinical Chemistry, University Hospital, University of Tübingen, Tübingen, Germany.
authors: Martina
authors: M
authors: Guthoff
authors: Krunoslav T
authors: KT
authors: Stingl
authors: Otto
authors: O
authors: Tschritter
authors: Maja
authors: M
authors: Rogic
authors: Martin
authors: M
authors: Heni
authors: Katarina
authors: K
authors: Stingl
authors: Manfred
authors: M
authors: Hallschmid
authors: Hans-Ulrich
authors: HU
authors: Häring
authors: Andreas
authors: A
authors: Fritsche
authors: Hubert
authors: H
authors: Preissl
authors: Anita M
authors: AM
authors: Hennige
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