The role of orexin in monetary and caloric reward anticipation and self-control: An fMRI study in narcolepsy patients
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2015-07-31
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en
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Introduction: Narcolepsy (NC) with cataplexy is a neurological sleeping disorder caused by an orexin deficiency. Besides sleep regulation, orexin signaling influences reward processing. As obesity is a common symptom in NC, we aimed to clarify the association between NC with a deficiency in orexin signaling and an increased BMI. Therefore we investigated the role of orexin in caloric- as well as monetary-related reward anticipation and self-control in patients with NC (n=27) compared with idiopathic hypersomnia (IH) (n=15) as well as healthy matched controls (HC) (n=21).
Methods: We used functional magnetic resonance imaging while participants performed a monetary- and caloric incentive delay task to measure the neural response towards high vs. low reward anticipation. Furthermore, we used a classic- and food Stroop task to measure the neuronal response towards incongruent vs. congruent and food words vs. neutral words.
Results and Interpretation: Our data indicates that NC patients do not suffer of a general cognitive control deficit, however they do suffer of alterations in the processing of food words. Our results showed increased ventral striatal activity during the processing of food words in NC- vs. IH patients and faster response times for NC patients vs. HC. These data provide a first indication that orexin may influence brain reward processing in a food specific way and this might explain the increased BMI over the course of the disease. However, the caloric incentive delay task did not support these effects, as there were no group differences for ventral striatal activity. Furthermore, we observed decreased activity in visual and motor preparatory brain regions within NC patients vs. HC (and IH patients) during the monetary- and caloric incentive delay tasks, which may reflect attentional and motivational dysfunction.
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Faculteit der Sociale Wetenschappen