title: Hierarchical prediction errors in midbrain and septum during social learning.
abstract: Social learning is fundamental to human interactions, yet its computational and physiological mechanisms are not well understood. One prominent open question concerns the role of neuromodulatory transmitters. We combined fMRI, computational modelling and genetics to address this question in two separate samples (N = 35, N = 47). Participants played a game requiring inference on an adviser's intentions whose motivation to help or mislead changed over time. Our analyses suggest that hierarchically structured belief updates about current advice validity and the adviser's trustworthiness, respectively, depend on different neuromodulatory systems. Low-level prediction errors (PEs) about advice accuracy not only activated regions known to support 'theory of mind', but also the dopaminergic midbrain. Furthermore, PE responses in ventral striatum were influenced by the Met/Val polymorphism of the Catechol-O-Methyltransferase (COMT) gene. By contrast, high-level PEs ('expected uncertainty') about the adviser's fidelity activated the cholinergic septum. These findings, replicated in both samples, have important implications: They suggest that social learning rests on hierarchically related PEs encoded by midbrain and septum activity, respectively, in the same manner as other forms of learning under volatility. Furthermore, these hierarchical PEs may be broadcast by dopaminergic and cholinergic projections to induce plasticity specifically in cortical areas known to represent beliefs about others.
authors.affiliation: Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland.|Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland.
authors.forename: Andreea O
authors.initials: AO
authors.lastname: Diaconescu
authors.affiliation: Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland.|Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland.|Max Planck UCL Centre for Computational Psychiatry and Ageing Research, London, UK.|Wellcome Trust Centre for Neuroimaging, University College London, London, UK.
authors.forename: Christoph
authors.initials: C
authors.lastname: Mathys
authors.affiliation: Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland.|Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland.
authors.forename: Lilian A E
authors.initials: LAE
authors.lastname: Weber
authors.affiliation: Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland.|Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland.
authors.forename: Lars
authors.initials: L
authors.lastname: Kasper
authors.affiliation: Max Planck Institute for Metabolism Research, Cologne, Germany.|Department of Pharmacology, Weill Medical College, Cornell University, New York, NY, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Mauer
authors.affiliation: Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland.|Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland.|Max Planck Institute for Metabolism Research, Cologne, Germany.|Wellcome Trust Centre for Neuroimaging, University College London, London, UK.
authors.forename: Klaas E
authors.initials: KE
authors.lastname: Stephan
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002394:Catechol O-Methyltransferase / Q000235:genetics; D003469:Culture; D004298:Dopamine / Q000235:genetics / Q000502:physiology*; D006801:Humans; D033182:Intention; D008279:Magnetic Resonance Imaging; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D009042:Motivation / Q000502:physiology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012688:Septum Pellucidum / Q000502:physiology*; D000067570:Social Learning / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics; D055815:Young Adult
chemical_list: D014446:Tyrosine 3-Monooxygenase; D002394:Catechol O-Methyltransferase; D004298:Dopamine
keywords: Bayesian inference; COMT; dopamine; fMRI; hierarchical prediction errors; theory of mind