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Abstract:
As social beings, humans are constantly probed to infer intentions from verbal and non- verbal communication and to react according to the kinematic signals of other people. In this way, social cognition is tightly bound to our ability to perceive, predict and perform socially relevant actions. Being characterized by impairments in social interactions, in- dividuals with autism spectrum disorder (ASD) demonstrate insensitivity to predictive social stimuli as well as abnormal kinematic control both on the behavioral and the brain level. Underlining the severe consequences of impaired social interactive capabilities, autistic individuals are at high risk of social exclusion and concomitant mental health issues. Therefore, the investigation of the behavioral and brain responses to social ac- tions might yield valuable insights into the fundamental dynamics of social interactions, which could lay the foundation for clinical research and interventions in ASD. In order to provide first insights, the main goal of this thesis was to identify the non-pathological brain mechanisms in perceptual action prediction and action control within a social context.
For this purpose, two functional magnetic resonance imaging (fMRI) experiments in healthy control participants were conducted: The first study of this thesis addressed the effect of observing communicative, i.e. predictive, actions on visual perception [interpersonal predictive coding (IPPC)]. By the use of point-light displays, we replicated behavioral findings of improved visual discriminability of a point-light agent after seeing a communicative as compared to an individual action of another point-light agent. Furthermore, our findings suggest a perceptual integration of social event knowledge implemented by the superior frontal gyrus (SFG) during predictive trials and a specific role of the amygdala in setting network configurations to meet the demands of the specific social context. Moving from a spectator perspective to direct involvement in a social interaction, the second study of this thesis examined the interaction of gaze processing and action control during an encounter with an anthropomorphic virtual character. The key finding of this second study comprises an increased functional coupling during high action control demands between the right temporoparietal junction (TPJ) as central gaze processing region and brain areas implicated in both action control processes and social cognition such as the inferior frontal gyri.
The results of the two studies demonstrate that predictive social actions as well as direct gaze signals can modify multimodal functional integration in the brain, thereby recruiting and modulating activation in brain structures implicated in ASD. In this way, the two studies of this thesis underline the interdependence of social cognition and kinematic processes while providing a reference point for future studies on ASD.
