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How other minds are represented in the human brain: Neural computations underlying Theory of Mind

Periodic Reporting for period 1 - ToMComputations (How other minds are represented in the human brain: Neural computations underlying Theory of Mind)

Reporting period: 2019-06-01 to 2021-05-31

What makes humans the most successful species on the planet? Most theories on human dominance attribute a special role to our hyper-sociality. We not only tolerate living in large groups, but we can collaborate to achieve goals, agree on abstract concepts like religions and companies, teach our young about things they haven’t encountered yet, and accumulate knowledge across generations. But what is the cause of our ability to achieve all these feats? All of these behaviours rely on an ability called Theory of Mind (ToM) - our ability to imagine what is in the mind of others. By “taking their perspective” we can understand their knowledge and beliefs of the world, even if that differs from our own. When we can achieve that, we can communicate, teach, and collaborate. The importance of this ability is dramatically demonstrated when it breaks down in various ways, such as in autism or in psychopathy.

Theory of Mind is, however, a multi-faceted concept. Many researchers mean slightly different things when using the term. This MSCA sought to provide an integrative model of Theory of Mind and its functional subprocesses. The main goal was to clarify which features of mental states are represented in brain areas implicated in social cognition.

To address this question, a combination of different approaches was used. Brain activation was analyzed and compared across various social cognition tasks with rich and complex, high-level stimuli. The identified areas and networks were also analyzed for plasticity effects related to frequent versus infrequent social contact. Finally, ongoing work is applying a computational model for the study of brain activation to differentiate components of belief representation for Theory of Mind reasoning.
"Throughout the project, three studies were carried out. In the first study, a meta-analysis of brain activation data reported from a total of 4,207 participants was performed, sampling across a wide variety of social tasks (Schurz et al., 2020b). Results show a continuum of brain activation across different task types and mental states (see Figure 1, from Schurz et al., 2020b, p.8). A novel observation of this meta-analysis is that brain systems for processing cognitive versus affective mental states frequently co-activate. This pattern of brain activation is linked to ecologically more valid forms of social cognition.

In the second study, the fellow further characterized co-activation between brain systems linked to cognitive and affective processing. A systematic review of brain activation and connectivity studies on social cognition was carried out. Two main types of cortical interactions were found. First, inhibitory interactions which are reflecting separation and functionally specialized processing. Second, excitatory interactions, which reflect integration and more flexible social processing.

In the third study, a large-scale multimodal brain imaging data set (n=~40,000) from the UK-Biobank population cohort was analyzed (Schurz et al., under review). Brain measures were related to participant's indicators of real-life social interactions. Results of the analysis show a consistent link between social contact and grey-matter morphology, as well as intrinsic functional connectivity of the brain. For both neural measures, relations to daily social interaction levels were found in the brain's salience and limbic systems. These systems are generally implicated in externally oriented processing anchored in the ""here-and-now"". They also are significant building-blocks of more affective processes involved in empathy necessary to feel into other people.

Finally, part of the project is ongoing work, which will continue after the end of the MSCA runtime. A computational model will be employed to differentiate components of belief representation and Theory of Mind in the brain.

References:
Schurz, M., Maliske, L., & Kanske, P. (2020a). Cross-network interactions in social cognition: A review of findings on task related brain activation and connectivity. Cortex, 130, 142-157.
Schurz, M., Radua, J., Tholen, M. G., Maliske, L., Margulies, D. S., Mars, R. B., ... & Kanske, P. (2020b). Toward a hierarchical model of social cognition: A neuroimaging meta-analysis and integrative review of empathy and theory of mind. Psychological Bulletin. Advance online publication. http://dx.doi.org/10.1037/bul0000303
Schurz, M., Uddin, L.Q. Kanske, P., Lamm, C., Sallet, J., Bernhardt, B., Mars, R.B. & Bzdok, D. (under review). Variability in brain structure and function reflects lack of peer support."
The project's results broaden our understanding of the neurocognitive implementation of Theory of Mind and are informative for clinical work, academic research, and public health.

Clinical relevance. An essential novel finding from study 1 (Schurz et al., 2020b) is that a specific group of Theory of Mind tasks activate brain areas implicated in both feeling and thinking based social cognition (i.e. affective and cognitive areas). This result puts the spotlight on a novel task group. It offers a new guide for selecting the best measures of ecologically relevant social abilities, both for nonimpaired and clinical populations.

Academic relevance. Results from study 1 also provide unprecedented empirical evidence of a detailed multilevel model of social cognition. This model offers a new framework for social cognition research and develops a solid multi-factorial model. Such models are the standard in established fields such as intelligence and personality research.

Societal relevance. Social interaction and support by peers are essential for mental and physical health. Even before the COVID-19 pandemic, solitary living made up >50% of the population in a growing number of metropolitan cities worldwide; and kept increasing at an alarming rate (World Health Organization). The findings from study 3 of this MSCA (Schurz et al., under review) add to the understanding of social support's brain and mental health impacts. Extending our knowledge of the thirst for social exchange has health implications and can guide social policy decision-making in the context of the current pandemic and future crises. It also informs public health interventions to combat the on-going decrease of social support and connection among individuals.
A continuum of brain activation across different task types and mental states