title: Why we interact: on the functional role of the striatum in the subjective experience of social interaction.
abstract: There is ample evidence that human primates strive for social contact and experience interactions with conspecifics as intrinsically rewarding. Focusing on gaze behavior as a crucial means of human interaction, this study employed a unique combination of neuroimaging, eye-tracking, and computer-animated virtual agents to assess the neural mechanisms underlying this component of behavior. In the interaction task, participants believed that during each interaction the agent's gaze behavior could either be controlled by another participant or by a computer program. Their task was to indicate whether they experienced a given interaction as an interaction with another human participant or the computer program based on the agent's reaction. Unbeknownst to them, the agent was always controlled by a computer to enable a systematic manipulation of gaze reactions by varying the degree to which the agent engaged in joint attention. This allowed creating a tool to distinguish neural activity underlying the subjective experience of being engaged in social and non-social interaction. In contrast to previous research, this allows measuring neural activity while participants experience active engagement in real-time social interactions. Results demonstrate that gaze-based interactions with a perceived human partner are associated with activity in the ventral striatum, a core component of reward-related neurocircuitry. In contrast, interactions with a computer-driven agent activate attention networks. Comparisons of neural activity during interaction with behaviorally naïve and explicitly cooperative partners demonstrate different temporal dynamics of the reward system and indicate that the mere experience of engagement in social interaction is sufficient to recruit this system.
authors.affiliation: Neuroimaging Lab, Department of Psychiatry, University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany; Institute of Neuroscience and Medicine - Cognitive Neuroscience (INM-3), Research Center Juelich, Leo-Brandt Strasse, 52428 Juelich, Germany. Electronic address: u.pfeiffer@fz-juelich.de.
authors.forename: Ulrich J
authors.initials: UJ
authors.lastname: Pfeiffer
authors.affiliation: Neuroimaging Lab, Department of Psychiatry, University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany.
authors.forename: Leonhard
authors.initials: L
authors.lastname: Schilbach
authors.affiliation: School of Psychology, University of Aberdeen, Aberdeen AB24 3FX, Scotland, UK.
authors.forename: Bert
authors.initials: B
authors.lastname: Timmermans
authors.affiliation: Neuroimaging Lab, Department of Psychiatry, University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany; Institute of Neuroscience and Medicine - Ethics in the Neurosciences (INM-8), Research Center Juelich, Leo-Brandt-Strasse, 52428 Juelich, Germany.
authors.forename: Bojana
authors.initials: B
authors.lastname: Kuzmanovic
authors.affiliation: Neuroimaging Lab, Department of Psychiatry, University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany.
authors.forename: Alexandra L
authors.initials: AL
authors.lastname: Georgescu
authors.affiliation: Department of Psychology, Faculty of Human Sciences, University of Cologne, Richard-Strauss-Strasse 2, 50931 Cologne, Germany.
authors.forename: Gary
authors.initials: G
authors.lastname: Bente
authors.affiliation: Neuroimaging Lab, Department of Psychiatry, University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany; Institute of Neuroscience and Medicine - Cognitive Neuroscience (INM-3), Research Center Juelich, Leo-Brandt Strasse, 52428 Juelich, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Vogeley
mesh_terms: D000328:Adult; D003299:Cooperative Behavior; D053483:Eye Movement Measurements; D005133:Eye Movements; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D007398:Interpersonal Relations; D008279:Magnetic Resonance Imaging; D008297:Male; D017397:Prefrontal Cortex / Q000502:physiology; D012201:Reward; D014584:User-Computer Interface; D066328:Ventral Striatum / Q000502:physiology*; D055815:Young Adult