Obesity is a major factor for the development of diabetes mellitus type 2 and the number of obese subjects increases especially in industrial countries. Insulin is a central nervous inhibitor of appetite and the peripheral insulin resistance is pathogenetic for diabetes mellitus type 2. We measured the cortical activity of humans after stimulation with pictures showing food or non-food related objects using whole-head magnetoencephalography (MEG) and investigated whether this activity is influenced by insulin. The MEG measurements were performed in 15 healthy humans during a hyperinsulinaemic-euglycaemic clamp in a placebo-controlled single-blind cross-over design. Every subject underwent 2 MEG recordings consisting of 3 blocks each (baseline, 1st level insulin/placebo infusion, 2nd level insulin/placebo infusion). The food stimuli elicited greater neuronal activity for the first component of the visual evoked response if compared to the control pictures (p = 0.050). There was a tendency of insulin to attenuate the difference between the neuronal activity for the food and the control pictures. These results suggest that there is a differential processing of food stimuli in human brain already in the early visual processing. Insulin can be a modulator of the central nervous processing of the nutritional stimuli.
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