title: Neural mechanisms of gain-loss asymmetry in temporal discounting.
abstract: Humans typically discount future gains more than losses. This phenomenon is referred to as the "sign effect" in experimental and behavioral economics. Although recent studies have reported associations between the sign effect and important social problems, such as obesity and incurring multiple debts, the biological basis for this phenomenon remains poorly understood. Here, we hypothesized that enhanced loss-related neural processing in magnitude and/or delay representation are causes of the sign effect. We examined participants performing intertemporal choice tasks involving future gains or losses and compared the brain activity of those who exhibited the sign effect and those who did not. When predicting future losses, significant differences were apparent between the two participant groups in terms of striatal activity representing delay length and in insular activity representing sensitivity to magnitude. Furthermore, participants with the sign effect exhibited a greater insular response to the magnitude of loss than to that of gain, and also a greater striatal response to the delay of loss than to that of gain. These findings may provide a new biological perspective for the development of novel treatments and preventive measures for social problems associated with the sign effect.
authors.affiliation: Department of Cognitive Neuroscience, ATR Brain Information Communication Research Laboratory Group, Kyoto 619-0288, Japan, Institute of Social and Economic Research, Osaka University, Osaka 567-0047, Japan, Faculty of Economics, Kindai University, Higashi-Osaka 577-0813, Japan, and Pharmaceutical Policy & Health Economics, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Saori C
authors.initials: SC
authors.lastname: Tanaka
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Yoneda
authors.forename: Fumio
authors.initials: F
authors.lastname: Ohtake
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping; D002755:Choice Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012201:Reward; D013997:Time Factors; D014838:Volunteers; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: delay discounting; fMRI; insula; loss aversion; sign effect; striatum
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