Neuroimaging studies have consistently identified a network of brain regions subserving
inferences of other humans' mental states. This network consists of the superior temporal
sulcus, temporoparietal junction, medial prefrontal cortex, temporal poles, and precuneus.
Little is known, however, about the neural substrate underlying Theory of Mind processes
in close to real-life conditions. To investigate those processes in more naturalistic
settings, we used an fMRI adaptation of the video-based Movie for the Assessment of
Social Cognition (MASC; Dziobek et al., 2006), which considers separate analysis of
implicit mental state reasoning during rapidly changing perceptual cues as demanded
in naturalistic settings and explicit mental state reasoning. We analyzed fMRI data
by means of both a standard general linear model (GLM) approach and a tensor probabilistic
independent component analysis (T-PICA), which is a novel model-free approach that
allows decomposition of activation into independent spatio-temporally coherent functional
networks. The model-based GLM approach revealed the typical explicit mental state
reasoning network. Complementary to the GLM approach, the model-free T-PICA approach
showed that those regions are also recruited during implicit mental state reasoning
and that they are represented in three independent, functionally connected networks.
The first component, mediating face processing and recognition, comprises the occipito-parietotemporal
cortices, while the second component, involved in language comprehension, comprises
the temporal lobes, lateral prefrontal cortex, and precuneus. The dorsomedial prefrontal
cortex and the precuneus comprise the third component, which is likely responsible
for self-referential mental activity. These results show that the mental state reasoning
network can be decomposed into circumscribed functional networks mediating differential
aspects of Theory of Mind.