Characterizing the theory of mind network in schizophrenia reveals a sparser network structure

Impaired social functioning is a hallmark of schizophrenia and altered functional integration between distant brain regions are expected to account for signs and symptoms of the disorder. The functional neuroarchitecture of a network relevant for social functioning, the mentalizing network, is however poorly understood. In this study we examined dysfunctions of the mentalizing network in patients with schizophrenia compared to healthy controls via dynamic causal modelling and an interactive social decision-making game. Network characteristics were analyzed on a single subject basis whereas graph theoretic metrics such as in-degree, out-degree and edge-connectivity per network node were compared between the groups. The results point to a sparser network structure in patients with schizophrenia and highlight the dorsomedial prefrontal cortex as a disconnected network hub receiving significantly less input from other brain regions in the network. Further analyses suggest that integrating pathways from the right and the left temporo-parietal junction into the dorsomedial prefrontal cortex were less frequently found in patients with schizophrenia. Brain and behavior analyses further suggest that the connectivity-intactness within the entire network is associated with functional interpersonal behavior during the task. Thus, the neurobiological alterations within the mentalizing network in patients with schizophrenia point to a specific integration deficit between core brain regions underlying the generation of higher-order representations and thereby provide a potential treatment target.