Effect of Intragastric Administration of Fatty Acids on Generalized Reward Sensitivity

This study aim to investigate the influence of intragastrically infused fatty acid on the generalization of responses to reward within the food domain and between financial and sexual domains.

Earlier research at the Faculty of Economics and Business (FEB) has demonstrated generalization of reward sensitivity after sensory stimulation in a different domain. As increased sensory stimulation in the sexual domain (Van den Bergh et al. 2008) or the power domain (Briers et al. 2007), the preference for immediate small financial reward increased deferred pay. Hongda, DeWitte & Warlop (2008) were able to neutralize this effect by domain-specific financial satiation. In this research, The investigators investigate the possible influence of (subliminal) intragastric administration of fatty acids in reward sensitivity in the power domain, and whether this effect generalizes to financial and sexual domain. Previous research at the Translational Research Center for Gastrointestinal Disorders (TARGID) showed that such administration can neutralize the effects of mood-priming (Van Oudenhove et al., 2011). This study aims to examine the implications of those findings in the motivational domain. 60 healthy heterosexual men come to the lab twice, once for the fatty acid condition, once for the control condition (counterbalanced, and randomly assigned to sequence condition). In each session the same dv's are measured (first three tasks counterbalanced, progressive ratio task always at the end). At the end of the second session, participants also compete a series of interindividual difference measures (scales). This research forms the start of a collaboration between TARGID and the Center for Research in Marketing and Consumer Science at KU Leuven Faculty of Business and Economics. The current paradigm is largely based on an earlier study by Prof. Dr. Lukas Van Oudenhove showing the effect of intragastric administration of an identical fatty acid solution tested for mood regulation (Van Oudenhove et al., 2011). The procedure performed in this study, which is placing a thin nasogastric tube is frequently used in the TARGID research and other research and is absolutely proven to be safe, with no mention of any adverse reactions during numerous previous studies. Similar studies by our research group had already been approved by the Medical Ethics Committee, and as always sees Prof. Tack ensure that the study conducted by researchers who have received adequate training and have acquired sufficient experience in this specific procedure before the start of the study. The procedure can be carried out in healthy volunteers in a perfectly safe manner.

Participants click the screens to get candies. The number of clicks will be used as a measurement of eating behavior.

Participants rate the attractiveness of 20 rewarding food pictures, 20 female face pictures on a 1-7 point scale.

Inclusion Criteria: Men, self-reporting as heterosexual Age: Adults (+ 17yr) 19 ≤ BMI ≤ 27 Exclusion Criteria: Participants must be in good health, both mental and physical. People with one or more of the following self-reported items applicable, are excluded: 1. History of or current presence of: Psychiatric disorders (among others, anxiety disorders, somatoform disorders, eating disorders, depression, addiction-related disorders, and the like) Abdominal / Thoracic Surgery (excl appendectomy or cholecystectomy) Neurological, endocrine or gastrointestinal-related disorders Other serious medical conditions. 2. Present the presence of: Pain Symptoms Use of medication that affects the function of the gastrointestinal tract and / or the nervous system; psychotropic drugs or pain killers A recent accident or an operation which one has not yet fully recovered. If it is positive answer to any of these criteria, participation will not be possible. These criteria are questioned in advance so that participants do not get unnecessarily turn up.

Briers, B., Pandelaere, M. & Warlop, L. (2007). Adding exchange to charity: A reference price explanation. Journal of Economic Psychology, 28, 15-30. doi: 10.1016/j.joep.2005.12.001.

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Van den Bergh, B., Dewitte, S. & Warlop, L. (2008). Bikinis instigate generalized impatience in intertemporal choice. Journal of Consumer Behavior, 35, 85-97. doi: 10.1086/525505

Van Oudenhove L, McKie S, Lassman D, Uddin B, Paine P, Coen S, Gregory L, Tack J, Aziz Q. Fatty acid-induced gut-brain signaling attenuates neural and behavioral effects of sad emotion in humans. J Clin Invest. 2011 Aug;121(8):3094-9. doi: 10.1172/JCI46380. Epub 2011 Jul 25.