title: Dopamine modulates egalitarian behavior in humans.
abstract: Egalitarian motives form a powerful force in promoting prosocial behavior and enabling large-scale cooperation in the human species [1]. At the neural level, there is substantial, albeit correlational, evidence suggesting a link between dopamine and such behavior [2, 3]. However, important questions remain about the specific role of dopamine in setting or modulating behavioral sensitivity to prosocial concerns. Here, using a combination of pharmacological tools and economic games, we provide critical evidence for a causal involvement of dopamine in human egalitarian tendencies. Specifically, using the brain penetrant catechol-O-methyl transferase (COMT) inhibitor tolcapone [4, 5], we investigated the causal relationship between dopaminergic mechanisms and two prosocial concerns at the core of a number of widely used economic games: (1) the extent to which individuals directly value the material payoffs of others, i.e., generosity, and (2) the extent to which they are averse to differences between their own payoffs and those of others, i.e., inequity. We found that dopaminergic augmentation via COMT inhibition increased egalitarian tendencies in participants who played an extended version of the dictator game [6]. Strikingly, computational modeling of choice behavior [7] revealed that tolcapone exerted selective effects on inequity aversion, and not on other computational components such as the extent to which individuals directly value the material payoffs of others. Together, these data shed light on the causal relationship between neurochemical systems and human prosocial behavior and have potential implications for our understanding of the complex array of social impairments accompanying neuropsychiatric disorders involving dopaminergic dysregulation.
authors: Helen Wills Neuroscience Institute, University of California, Berkeley, 175 Li Ka Shing Center, Berkeley, CA 94720, USA; Haas School of Business, University of California, Berkeley, 2220 Piedmont Avenue, Berkeley, CA 94720, USA.
authors: Ignacio
authors: I
authors: Sáez
authors: Virginia Tech Carilion Research Institute, 2 Riverside Circle, Roanoke, VA 24016, USA.
authors: Lusha
authors: L
authors: Zhu
authors: Helen Wills Neuroscience Institute, University of California, Berkeley, 175 Li Ka Shing Center, Berkeley, CA 94720, USA; Haas School of Business, University of California, Berkeley, 2220 Piedmont Avenue, Berkeley, CA 94720, USA.
authors: Eric
authors: E
authors: Set
authors: Helen Wills Neuroscience Institute, University of California, Berkeley, 175 Li Ka Shing Center, Berkeley, CA 94720, USA; Department of Neurology, University of California, San Francisco, 500 Parnassus Avenue, San Francisco, CA 94143, USA; Department of Neurology, VA Northern California Health Care System, 150 Muir Road, Martinez, CA 94553, USA. Electronic address: andrew.kayser@ucsf.edu.
authors: Andrew
authors: A
authors: Kayser
authors: Helen Wills Neuroscience Institute, University of California, Berkeley, 175 Li Ka Shing Center, Berkeley, CA 94720, USA; Haas School of Business, University of California, Berkeley, 2220 Piedmont Avenue, Berkeley, CA 94720, USA. Electronic address: mhsu@haas.berkeley.edu.
authors: Ming
authors: M
authors: Hsu
mesh_terms: D000328:Adult; D000533:Altruism; D001577:Benzophenones / Q000494:pharmacology; D065098:Catechol O-Methyltransferase Inhibitors / Q000494:pharmacology; D002755:Choice Behavior / Q000187:drug effects*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D005716:Game Theory; D006801:Humans; D008297:Male; D009042:Motivation / Q000187:drug effects*; D009596:Nitrophenols / Q000494:pharmacology; D012919:Social Behavior; D000077867:Tolcapone
chemical_list: D001577:Benzophenones; D065098:Catechol O-Methyltransferase Inhibitors; D009596:Nitrophenols; D000077867:Tolcapone; D004298:Dopamine