title: Dynamical Representation of Dominance Relationships in the Human Rostromedial Prefrontal Cortex.
abstract: Humans and other primates have evolved the ability to represent their status in the group's social hierarchy, which is essential for avoiding harm and accessing resources. Yet it remains unclear how the human brain learns dominance status and adjusts behavior accordingly during dynamic social interactions. Here we address this issue with a combination of fMRI and transcranial direct current stimulation (tDCS). In a first fMRI experiment, participants learned an implicit dominance hierarchy while playing a competitive game against three opponents of different skills. Neural activity in the rostromedial PFC (rmPFC) dynamically tracked and updated the dominance status of the opponents, whereas the ventromedial PFC and ventral striatum reacted specifically to competitive victories and defeats. In a second experiment, we applied anodal tDCS over the rmPFC to enhance neural excitability while subjects performed a similar competitive task. The stimulation enhanced the relative weight of victories over defeats in learning social dominance relationships and exacerbated the influence of one's own dominance over competitive strategies. Importantly, these tDCS effects were specific to trials in which subjects learned about dominance relationships, as they were not present for control choices associated with monetary incentives but no competitive feedback. Taken together, our findings elucidate the role of rmPFC computations in dominance learning and unravel a fundamental mechanism that governs the emergence and maintenance of social dominance relationships in humans.
authors.affiliation: Neuroeconomics, Reward and Decision Making Group, Center for Cognitive Neurosciences, CNRS, University of Lyon 1, 69675 Lyon, France. Electronic address: r.ligneul@donders.ru.nl.
authors.forename: Romain
authors.initials: R
authors.lastname: Ligneul
authors.affiliation: Neuroeconomics, Reward and Decision Making Group, Center for Cognitive Neurosciences, CNRS, University of Lyon 1, 69675 Lyon, France.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Obeso
authors.affiliation: Laboratory for Social and Neural Systems Research (SNS Lab), Department of Economics, University of Zurich, 8091 Zurich, Switzerland.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Ruff
authors.affiliation: Neuroeconomics, Reward and Decision Making Group, Center for Cognitive Neurosciences, CNRS, University of Lyon 1, 69675 Lyon, France. Electronic address: dreher@isc.cnrs.fr.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Dreher
mesh_terms: D004558:Electric Stimulation; D006801:Humans; D007858:Learning; D008279:Magnetic Resonance Imaging; D017397:Prefrontal Cortex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D012930:Social Dominance
keywords: fMRI; locus of control; mPFC; performance; reinforcement-learning; social dominance; social hierarchy; social learning; tDCS; ventral striatum